JP5351575B2 - Solidification crack prediction method, casting method using the same, solidification crack prediction device, and solidification crack prediction program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solidification cracking prediction method for predicting difficulty/easiness of solidification cracking when the casting of an Al alloy made of desired alloy components is subjected to semi-continuous casting by a vertical type direct water-cooled system. <P>SOLUTION: The method includes: an input step S1; a first calculation step S2 where calculation of a temperature variation &Delta;Tii based on (formula 1) and calculation of a difference &Delta;R based on (formula 2) are performed, a second calculation step S3 where relation among the calculated difference &Delta;R, the calculated temperature variation &Delta;Tii and the casting velocity v is calculated on the basis of (formula 3); a prediction step S4 where, in the case the relation among the calculated difference &Delta;R, the temperature variation &Delta;Tii and the casting velocity v satisfies the following (formula 3), it is predicted that solidification cracking is hard to occur; and an output step S5. Formula 1: &Delta;Ti=(T<SB>FsL</SB>-T<SB>FsH</SB>)&times;ä(FsL-FsH)/0.2}. Formula 2: &Delta;R=[&delta;T/&delta;fs]<SB>fs=FsL</SB>-[&delta;T/&delta;fs]<SB>fs=FsH</SB>. Formula 3: &Delta;R/&Delta;Tii&lt;1,020&times;&Delta;Tii/v<SP>2</SP>. In the formulae, &delta; denotes a partial differential symbol. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a solidification crack prediction method for predicting the difficulty of solidification cracking observed in the solidification process when casting an Al (aluminum) alloy casting, a casting method using the solidification crack, a solidification crack prediction device, and a solidification It relates to a crack prediction program.

  Solidification cracking observed in the solidification process when casting a cast such as an ingot of Al alloy is one of the major drawbacks of industrial products that undergo casting. This solidification cracking is considered to occur as follows.

The Al alloy contains Al as a main component and various elements such as Fe, Si, Mn, Mg, Cu, and Zn are added. In Al alloys, these additive elements are accompanied by eutectic reactions as solute elements, so they are easily concentrated in the residual melt (liquid phase) during the solidification process, and the solidification temperature of the Al alloy increases as the elements concentrate in the liquid phase. descend. In the cooling process, thermal stress accompanying thermal shrinkage is generated in the solid phase of the solidification process, but when the above-mentioned elements are concentrated in the liquid phase and the solidification temperature is lowered, cracks are caused by strain due to thermal contraction generated by cooling. Occur.
In general, it is considered that the wider the solidification temperature range (the greater the amount of temperature change during solidification), the more likely it is that solidification cracking will occur, and it is desirable to determine an optimal alloy composition that minimizes this. However, it does not necessarily prevent the occurrence of solidification cracks.

  A cast product in which solidification cracking has occurred is extremely difficult to divert to a subsequent process. Therefore, basically, the cast product must be remelted as scrap, resulting in enormous loss. Therefore, it is very important to determine the influence of the alloy components on the solidification cracking and the quantitative determination of the solidification cracking safety factor in the casting process. Therefore, it is desired to develop a method for predicting the difficulty of solidification cracking. Ideally, the difficulty of solidification cracking can be predicted in advance during product development, etc., and the optimal alloy composition that can prevent solidification cracking can be found in advance, or the solidification cracking of a cast product made of an existing alloy composition. Development of a method that can grasp the safety factor in advance is desired.

In order to prevent solidification cracking, manufacturers that cast Al alloy castings reduce the casting speed in the case of continuous casting, or add a finer containing mainly Ti.
For example, a method of optimizing continuous casting conditions, particularly a cooling method as in Patent Document 1, or a method of grasping the easiness of cracking by performing thermal / thermal strain analysis as in Patent Document 2 is used. It has been.
Further, for example, as disclosed in Patent Document 3, alloy components that are difficult to break and their compositions are restricted and used.

JP 2000-107842 A JP 2004-82150 A JP-A-7-157840

However, if the casting speed is reduced by continuous casting, the productivity of the cast product may be reduced, and if a finer is added, the recyclability may be reduced.
In the techniques of Patent Documents 1 and 2, since the conditions differ for each alloy component, it is basically necessary to confirm the easiness of solidification cracking by the same method when changing the alloy composition. Become.
In addition, since the component composition is limited in the technique of Patent Document 3, an Al alloy casting made of a desired alloy component cannot be cast.
In any of these techniques, it is impossible to predict the difficulty of solidification cracking when casting an Al alloy casting made of a desired alloy component.

  The present invention has been made in view of such circumstances, and its purpose is to reduce the difficulty of solidification cracking when semi-continuous casting of an Al alloy casting made of a desired alloy component is performed by a vertical direct water cooling method. It is an object of the present invention to provide a solidification crack prediction method that can be predicted, a casting method using the solidification crack prediction method, a solidification crack prediction device, and a solidification crack prediction program.

(1) The solidification crack prediction method according to the present invention that solves the above-mentioned problems is to predict the difficulty of solidification cracks observed in the solidification process when semi-continuous casting of an Al alloy casting is performed by a vertical direct water cooling method. of a solidification crack prediction method, it casts an input step of inputting the forming speed, based on the following (equation 1), the solid fraction of the Al alloy of any one point between 0.75 ± 0.05 Based on the calculation of the temperature change amount ΔTii when the solid fraction changes from the solid fraction FsL to any one of the solid fraction FsH between 0.95 ± 0.03, and the following (formula 2), The difference ΔR between the temperature change amount per unit solid phase rate when the solid phase rate of the Al alloy is FsL and the temperature change amount per unit solid phase rate when the solid phase rate is FsH is calculated. 1 based on the calculation step and the following (Equation 3), the calculated difference ΔR, the calculated temperature change A second calculation step for calculating the relationship between the amount ΔTii and the input casting speed v (mm / min); the calculated difference ΔR; the calculated temperature change amount ΔTii; and the input casting speed v (mm / min) When the relationship satisfies the following (Equation 3), it includes a prediction step of predicting (determining) that solidification cracking is difficult, and an output step of outputting a result predicted by the prediction step.

_{ΔTii = (T FsL -T FsH)} / {(Fs H -Fs L) /0.2} ··· ( Equation 1)
ΔR = [∂T / ∂fs] _{fs = FsL−} [∂T / ∂fs] _{fs = FsH} (Expression 2)
ΔR / ΔTii <1020 × ΔTii / v ² (Formula 3)

However, in said (Formula 1)-(Formula 3), FsL represents the solid-phase rate of any one point between 0.75 +/- 0.05, FsH is between 0.95 +/- 0.03. represent solid fraction of any one point, T _FSL represents the temperature when the solid phase rate is the FSL, T _FSH represents the temperature when the solid phase rate is the FSH, [∂T / ∂fs] represents a temperature change amount per unit solid phase ratio given by fs, and v represents a casting speed (mm / min).

  Thus, the solidification crack prediction method according to the present invention calculates the calculation formulas shown in (Formula 1) to (Formula 3), and the calculated result is the specific relational formula shown in (Formula 3). If the above conditions are satisfied, the relationship between the type and content of the additive element of the Al alloy and the casting speed is appropriate, and the Al alloy is predicted to be difficult to solidify cracking because it can be judged (determined) that the sensitivity to solidification cracking is low. It is possible.

(2) In the present invention, when the temperature change amount ΔTii is calculated using a general-purpose thermodynamic database, and the Al alloy is a binary or higher Al alloy, the temperature change seeking the temperature T _{Fs L} when the solid fraction of the FsL by, and a temperature T _{Fs H} when the solid fraction the FsH using Scheil module is in the liquid phase complete mixing model The amount ΔTii is preferably calculated. In this way, in the case where the Al alloy is a binary system or more, the relationship between the solid phase ratio and the temperature when the solid phase ratio changes as the Al alloy solidifies can be calculated more appropriately. Therefore, the temperature change amount ΔTii can be calculated more appropriately.

(3) In this invention, it is preferable that the said solidification crack is a surface crack. In this way, surface cracks can be appropriately predicted as solidification cracks.

(4) A casting method according to the present invention is a casting method for casting an Al alloy casting using the solidification crack prediction method according to any one of (1) to (3), Input step for inputting the kind and amount of additive element that can be added to the Al alloy, the numerical range of the allowable additive amount of the additive element, the casting speed, and the numerical range of the allowable speed of the casting speed, and the input step A storage step for storing the kind of additive element that is allowed to be added to the Al alloy, the numerical value range of the allowable addition amount of the additive element, and the numerical range of the allowable speed of the casting speed; Based on the formula (1), the solid fraction of the Al alloy is between 0.75 ± 0.05 and the solid fraction of FsL at any one point is between 0.95 ± 0.03. When the solid phase ratio changes to one point FsH Based on the calculation of temperature change ΔTii and the following (formula 2), the temperature change amount per unit solid phase rate when the solid phase rate of the Al alloy is FsL and the unit solid phase when the solid rate is FsH The first calculation step for calculating the difference ΔR with respect to the temperature change amount per rate, and the calculated difference ΔR, the calculated temperature change amount ΔTii, and the input casting speed based on the following (Equation 3) The relationship between the second calculation step for calculating the relationship of v (mm / min), the calculated difference ΔR, the calculated temperature change amount ΔTii, and the casting speed v (mm / min) is expressed by the following (Equation 3). When it is predicted that solidification cracking is difficult when it is satisfied, and when these relationships do not satisfy the following (Equation 3), a prediction step that predicts that solidification cracking is likely to occur; , Type of additive element, numerical value of additive amount of additive element And a resetting step for resetting the casting speed within the numerical range of the type of the additive element stored in the storing step, the allowable addition amount of the additive element, and the numerical range of the allowable speed of the casting speed; A re-execution step that is re-executed from the first calculation step with the content reset in the reset step, and predicting that solidification cracking is difficult in the prediction step. It is characterized in that the cast product is cast at the kind and amount of the added element and the casting speed.

_{ΔTii = (T FsL -T FsH)} / {(Fs H -Fs L) /0.2} ··· ( Equation 1)
ΔR = [∂T / ∂fs] _{fs = FsL−} [∂T / ∂fs] _{fs = FsH} (Expression 2)
ΔR / ΔTii <1020 × ΔTii / v ² (Formula 3)

However, in said (Formula 1)-(Formula 3), FsL represents the solid-phase rate of any one point between 0.75 +/- 0.05, FsH is between 0.95 +/- 0.03. represent solid fraction of any one point, T _FSL represents the temperature when the solid phase rate is the FSL, T _FSH represents the temperature when the solid phase rate is the FSH, [∂T / ∂fs] represents a temperature change amount per unit solid phase ratio given by fs, and v represents a casting speed (mm / min).

  In this way, the temperature change amount ΔTii calculated based on (Equation 1) before casting the cast product, the difference ΔR calculated based on (Equation 2), and the casting speed v are ( The difficulty of solidification cracking is predicted by determining whether or not a specific relational expression calculated based on Equation 3) is satisfied, and the Al alloy is predicted to become difficult to solidify cracking. Since it is possible to adjust the type and content of the additive element that is allowed to be added and the casting speed, it is possible to prevent solidification cracks from occurring.

(5) A solidification crack prediction device according to the present invention is a solidification crack prediction device for predicting the difficulty of solidification cracks observed in the solidification process when semi-continuous casting of an Al alloy casting is performed by a vertical direct water cooling method. a is, cast input means for inputting the forming speed, based on the following (formula 1), from the solid phase ratio FsL any one point between the solid fraction 0.75 ± 0.05 of the Al alloy Calculation of temperature change amount ΔTii when the solid phase ratio changes to any one solid phase ratio FsH between 0.95 ± 0.03 and solidification of the Al alloy based on the following (formula 2) A first calculating means for calculating a difference ΔR between a temperature change amount per unit solid phase ratio when the phase ratio is FsL and a temperature change amount per unit solid phase ratio when the solid phase ratio is FsH; Based on the following (formula 3), the calculated difference ΔR, the calculated temperature change amount ΔTii, and the input casting The relationship between the second calculation means for calculating the relationship between the forming speed v (mm / min), the calculated difference ΔR, the calculated temperature change amount ΔTii, and the input casting speed v (mm / min) is as follows (formula: 3) It has a prediction means for predicting that solidification cracking is difficult when the condition is satisfied, and an output means for outputting the result predicted by the prediction means.

_{ΔTii = (T FsL -T FsH)} / {(Fs H -Fs L) /0.2} ··· ( Equation 1)
ΔR = [∂T / ∂fs] _{fs = FsL−} [∂T / ∂fs] _{fs = FsH} (Expression 2)
ΔR / ΔTii <1020 × ΔTii / v ² (Formula 3)

However, in said (Formula 1)-(Formula 3), FsL represents the solid-phase rate of any one point between 0.75 +/- 0.05, FsH is between 0.95 +/- 0.03. represent solid fraction of any one point, T _FSL represents the temperature when the solid phase rate is the FSL, T _FSH represents the temperature when the solid phase rate is the FSH, [∂T / ∂fs] represents a temperature change amount per unit solid phase ratio given by fs, and v represents a casting speed (mm / min).

  Thus, the solidification crack prediction device according to the present invention calculates the calculation formulas shown in (Formula 1) to (Formula 3), and the calculated result is a specific relational formula shown in (Formula 3). In the case of satisfying the above, it is possible to predict that solidification cracking is difficult because the relationship between the type and amount of additive element of the Al alloy and the casting speed is appropriate.

(6) A solidification crack prediction device according to the present invention is a solidification crack prediction device for predicting the difficulty of solidification cracks seen in the solidification process when semi-continuous casting of an Al alloy casting is performed by a vertical direct water cooling method. An input means for inputting the kind and amount of an additive element that can be added to the Al alloy, a numerical range of the allowable additive amount of the additive element, a casting speed, and a numerical range of the allowable speed of the casting speed. And the type of additive element that can be added to the Al alloy input by the input means, the numerical range of the allowable addition amount of the additive element, and the numerical range of the allowable speed of the casting speed are stored. The solid phase ratio is 0.95 ± 0.00 from one point solid phase ratio FsL when the solid phase ratio of the Al alloy is between 0.75 ± 0.05 based on the following (Formula 1). Up to FsH at any one point between 03 Calculation of temperature change amount ΔTii when changing, and temperature change amount per unit solid phase rate when the solid phase rate of the Al alloy is FsL and the solid phase rate is FsH based on the following (formula 2) Calculating a difference ΔR with respect to a temperature change amount per unit solid-phase ratio, the calculated difference ΔR based on the following (Equation 3), the calculated temperature change amount ΔTii, and an input The relationship between the calculated second casting speed v (mm / min), the calculated difference ΔR, the calculated temperature change ΔTii, and the casting speed v (mm / min) is as follows: Prediction means that solidification cracking is difficult to predict when Expression 3) is satisfied, and prediction that the solidification cracking is likely to occur when these relationships do not satisfy the following (Expression 3); If it is, the type and amount of the additive element, and the casting speed, A resetting means for resetting the type of the additive element stored in the storage means, within a numerical range of the allowable addition amount of the additive element, and within a numerical range of the allowable speed of the casting speed; and the resetting means, It has the re-execution means to re-execute from the said 1st calculation means with the reset content, and the output means which outputs the result estimated by the said prediction means, It is characterized by the above-mentioned.

_{ΔTii = (T FsL -T FsH)} / {(Fs H -Fs L) /0.2} ··· ( Equation 1)
ΔR = [∂T / ∂fs] _{fs = FsL−} [∂T / ∂fs] _{fs = FsH} (Expression 2)
ΔR / ΔTii <1020 × ΔTii / v ² (Formula 3)

However, in said (Formula 1)-(Formula 3), FsL represents the solid-phase rate of any one point between 0.75 +/- 0.05, FsH is between 0.95 +/- 0.03. represent solid fraction of any one point, T _FSL represents the temperature when the solid phase rate is the FSL, T _FSH represents the temperature when the solid phase rate is the FSH, [∂T / ∂fs] represents a temperature change amount per unit solid phase ratio given by fs, and v represents a casting speed (mm / min).

  Thus, the solidification crack prediction device according to the present invention calculates the calculation formulas shown in (Formula 1) to (Formula 3), and the calculated result is a specific relational formula shown in (Formula 3). In the case of satisfying the above, it is possible to predict that solidification cracking is difficult because the relationship between the composition, composition and casting speed of the Al alloy is appropriate. On the other hand, when it is predicted that solidification cracking is likely to occur, the solidification crack prediction apparatus according to the present invention is the kind of additive element that can be added to the Al alloy that has been input and stored in advance, and the allowable addition amount of the additive element Within the numerical range of the above, within the numerical range of the allowable speed of the casting speed, after resetting the type and addition amount of the additive element, and the casting speed, re-execution from the first calculating means, from (Formula 1) to (Formula 3) ) Is repeated, it is possible to predict the type and content of the additive element and the casting speed of the Al alloy that are difficult to solidify and crack.

(7) The solidification crack prediction program according to the present invention is a solidification crack prediction program for predicting the difficulty of solidification cracks seen in the solidification process when semi-continuous casting of an Al alloy casting is performed by a vertical direct water cooling method. In this case, the computer calculates the solid phase ratio from the solid phase ratio FsL at any one point of the Al alloy between 0.75 ± 0.05 based on the following (formula 1) to a solid phase ratio of 0.1. Based on the calculation of the temperature change amount ΔTii when changing to the solid phase rate FsH at any one point between 95 ± 0.03 and the solid phase rate of the Al alloy is FsL based on the following (Equation 2) Based on the following (Formula 3), the first calculation means for calculating the difference ΔR between the temperature change amount per unit solid phase rate and the temperature change amount per unit solid phase rate when the solid phase rate is FsH , The calculated difference ΔR, the calculated temperature change ΔTii, and the casting speed v (mm / in) the second calculation means for calculating the relationship, and the solidification cracking when the calculated difference ΔR, the calculated temperature change ΔTii, and the casting speed v (mm / min) satisfy the following (Equation 3): It is characterized by functioning as a predicting means for predicting that it is difficult.

_{ΔTii = (T FsL -T FsH)} / {(Fs H -Fs L) /0.2} ··· ( Equation 1)
ΔR = [∂T / ∂fs] _{fs = FsL−} [∂T / ∂fs] _{fs = FsH} (Expression 2)
ΔR / ΔTii <1020 × ΔTii / v ² (Formula 3)

However, in said (Formula 1)-(Formula 3), FsL represents the solid-phase rate of any one point between 0.75 +/- 0.05, FsH is between 0.95 +/- 0.03. represent solid fraction of any one point, T _FSL represents the temperature when the solid phase rate is the FSL, T _FSH represents the temperature when the solid phase rate is the FSH, [∂T / ∂fs] represents a temperature change amount per unit solid phase ratio given by fs, and v represents a casting speed (mm / min).

  Thus, the solidification crack prediction program according to the present invention shows the result calculated by causing the computer to function to calculate the calculation formulas shown in (Formula 1) to (Formula 3). When the specific relational expression is satisfied, it is possible to predict that solidification cracking is difficult because the relationship between the type and amount of additive element of the Al alloy and the casting speed is appropriate for the computer.

(8) The solidification crack prediction program according to the present invention is a solidification crack prediction program for predicting the difficulty of solidification cracks seen in the solidification process when semi-continuous casting of an Al alloy casting is performed by a vertical direct water cooling method. In this case, the computer calculates the solid phase ratio from the solid phase ratio FsL at any one point of the Al alloy between 0.75 ± 0.05 based on the following (formula 1) to a solid phase ratio of 0.1. Based on the calculation of the temperature change amount ΔTii when changing to the solid phase rate FsH at any one point between 95 ± 0.03 and the solid phase rate of the Al alloy is FsL based on the following (Equation 2) Based on the following (Formula 3), the first calculation means for calculating the difference ΔR between the temperature change amount per unit solid phase rate and the temperature change amount per unit solid phase rate when the solid phase rate is FsH , The calculated difference ΔR, the calculated temperature change ΔTii, and the casting speed v (mm / in) the second calculation means for calculating the relationship, the calculated difference ΔR, the calculated temperature change amount ΔTii, and the relationship between the casting speed v (mm / min) satisfy the following (formula 3). difficult and predicted, prediction means these relationships to predict the likely Shi cracks solidifies is not satisfied following (equation 3), when it is predicted crack Shi easily and solidify in said prediction means, the type of added pressure element And the addition amount and the casting speed are stored in the storage means in advance within the numerical value range of the additive element, the allowable addition amount of the additive element, and the allowable speed range of the casting speed. It is characterized by functioning as a resetting means for setting and a re-execution means for re-execution from the first calculation means with the contents reset by the resetting means.

_{ΔTii = (T FsL -T FsH)} / {(Fs H -Fs L) /0.2} ··· ( Equation 1)
ΔR = [∂T / ∂fs] _{fs = FsL−} [∂T / ∂fs] _{fs = FsH} (Expression 2)
ΔR / ΔTii <1020 × ΔTii / v ² (Formula 3)

However, in said (Formula 1)-(Formula 3), FsL represents the solid-phase rate of any one point between 0.75 +/- 0.05, FsH is between 0.95 +/- 0.03. represent solid fraction of any one point, T _FSL represents the temperature when the solid phase rate is the FSL, T _FSH represents the temperature when the solid phase rate is the FSH, [∂T / ∂fs] represents a temperature change amount per unit solid phase ratio given by fs, and v represents a casting speed (mm / min).

  As described above, the solidification crack prediction program according to the present invention has a specific relationship in which the result calculated by causing the computer to calculate the calculation formulas shown in (Formula 1) to (Formula 3) is shown in (Formula 3). If the equation is satisfied, the computer can predict that solidification cracking is difficult because the relationship between the type and amount of additive element of the Al alloy and the casting speed is appropriate. On the other hand, when it is predicted by the computer that solidification cracking is likely to occur, the solidification crack prediction program according to the present invention is the kind of additive element that can be added to the Al alloy that has been input and stored in advance, After resetting the type and addition amount of the additive element and the casting speed within the numerical range of the allowable addition amount and within the numerical range of the allowable speed of the casting speed, the computer is re-executed from the first calculating means (formula Since the calculation of (Equation 3) from 1) is repeated, it is possible to predict the type and amount of additive element and the casting speed of the Al alloy that are difficult to solidify and crack.

  According to the solidification crack prediction method of the present invention, the temperature change amount ΔTii calculated based on (Expression 1), the difference ΔR calculated based on (Expression 2), and the casting speed v By determining whether or not the specific relational expression calculated based on 3) is satisfied, it is possible to predict the difficulty of solidification cracking when casting a cast product of an Al alloy made of a desired alloy component.

  According to the casting method of the present invention, the temperature change amount ΔTii calculated based on (Expression 1), the difference ΔR calculated based on (Expression 2), and the casting speed v are expressed by (Expression 3). Predicting the difficulty of solidification cracking by judging whether or not a specific relational expression calculated based on the above is satisfied, and the type and amount of additive element of the Al alloy until it is predicted that such solidification cracking is unlikely to occur, Since the casting speed is adjusted, it is possible to prevent solidification cracks from occurring when casting a cast product. Therefore, it is possible to eliminate the loss of re-melting and using the cast product in which the solidification crack has occurred. Therefore, productivity can be improved.

According to the solidification crack prediction apparatus according to the present invention, the temperature change amount ΔTii calculated based on (Expression 1), the difference ΔR calculated based on (Expression 2), and the casting speed v are expressed by (Expression 1). By determining whether or not the specific relational expression calculated based on 3) is satisfied, it is possible to predict the difficulty of solidification cracking when casting a cast product of an Al alloy made of a desired alloy component.
In addition, according to the solidification crack prediction apparatus according to the present invention, within the numerical range of the additive element type and the allowable addition amount added to the Al alloy inputted in advance and within the numerical range of the allowable speed of the casting speed, The type, amount added, and casting speed are reset, the first calculation unit is re-executed with the reset content, and this is repeated until it is predicted that solidification cracking is difficult. The amount added and the coagulation rate can be predicted.

According to the solidification crack prediction program according to the present invention, using a computer, the temperature change amount ΔTii calculated based on (Equation 1), the difference ΔR calculated based on (Equation 2), and the casting speed v And whether or not a specific relational expression calculated based on (Equation 3) is satisfied, and predicting the difficulty of solidification cracking when casting an Al alloy casting made of a desired alloy component Can do.
Further, according to the solidification crack prediction program according to the present invention, in the numerical range of the additive element type and the allowable addition amount to be added to the Al alloy inputted in advance in the computer, and within the numerical range of the allowable speed of the casting speed, Re-set the type and amount of additive element and casting speed, re-execute from the first calculation means with the reset content, and repeat this until it is predicted that solidification cracking is difficult. It is possible to predict the type and amount of element added and the solidification rate.

It is a flowchart which shows the flow of the solidification crack prediction method which concerns on this invention. It is the schematic explaining a mode that DC casting of the cast product of Al alloy by a vertical direct water cooling system. FIG. 3 is an explanatory diagram for explaining a state in which solidification cracking occurs in DC casting, which is a main part enlarged portion of FIG. 2. It is a graph which shows the relationship between a solid-phase rate and temperature. It is a conceptual diagram explaining the generation | occurrence | production mechanism of the solidification crack in the area | region I, the area | region II, and the area | region III which were shown in FIG.3 and FIG.4. It is a flowchart which shows the flow of the casting method which concerns on this invention. It is a block diagram explaining one embodiment of a solidification crack prediction device and a solidification crack prediction program concerning the present invention. It is a block diagram explaining other embodiment of the solidification crack prediction apparatus and solidification crack prediction program which concern on this invention. No. It is the graph which plotted the presence or absence of the solidification crack in 1-17, Comprising: (a) is a graph in case the casting speed v is 60 mm / min, (b) is the casting speed v 80 mm / min. (C) is a graph when the casting speed v is 100 mm / min.

Next, the solidification crack prediction method according to the present invention will be described in detail with reference to FIG.
As shown in FIG. 1, the method for predicting solidification cracking according to the present invention reduces the difficulty of solidification cracking seen in the solidification process when semi-continuous casting (DC casting) of an Al alloy casting is performed by a vertical direct water cooling method. This is a solidification crack prediction method for prediction, and is performed by the procedure of an input step S1, a first calculation step S2, a second calculation step S3, a prediction step S4, and an output step S5.

Here, before explaining the details of each step, the vertical direct water cooling DC casting will be explained.
As shown in FIG. 2, a DC casting apparatus 1 that performs DC casting includes a launder 3 containing an Al alloy melt 2, a float system that is provided under the loader 3, and flows the Al alloy melt 2 laterally. The molten metal surface control system 4, a mold 5 provided so as to surround the molten metal surface control system 4, and a bottom block 6 provided below the mold 5 and pulled down by a hydraulic cylinder (not shown). Yes. The above-described mold 5 is filled with cooling water 7, and the casting 8 exhibits a predetermined shape by cooling the molten metal 2. Further, at the bottom of the mold 5, a discharge portion 9 is provided for discharging the cooling water 7 toward the Al alloy casting 8 pulled down by the bottom block 6 and cooling the casting 8. When the casting 8 has a predetermined length, the casting 8 having a predetermined shape and size is manufactured by stopping the injection of the molten metal 2 into the mold 5 and the lowering of the bottom block 6. As the molten metal level control system 4, not only the float system illustrated in FIG. 2 but also a nozzle stopper system (not shown) that detects the molten metal level and adjusts the molten metal supply amount may be used. .

  The solidification crack prediction method according to the present invention comprises such an Al alloy prior to casting the cast product 8 using an Al alloy having a new or desired composition component, for example, when performing such DC casting. The present invention provides a method for predicting whether or not the casting 8 is difficult to solidify and crack.

Solidification cracking prediction method according to the present invention, as shown in FIG. 1, and inputs the forming speed cast in the input step S1. The solid phase rate of the Al alloy at each temperature is determined by the type and amount of the additive element (more specifically, the solid phase rate of the Al alloy is the residual amount of the additive element remaining in the liquid phase at each temperature. Depending on.)

  Then, in the first calculation step S2, the solid phase ratio is reduced from the solid phase ratio FsL at any one point between the solid phase ratios of Al alloys based on the following (formula 1) to 0.75 ± 0.05. Calculation of temperature change ΔTii when changing to solid phase rate FsH at any one point between 95 ± 0.03, and unit when solid phase rate of Al alloy is FsL based on (Equation 2) below The difference ΔR between the temperature change amount per solid phase rate and the temperature change amount per unit solid phase rate when the solid phase rate is FsH is calculated.

_{ΔTii = (T FsL -T FsH)} / {(Fs H -Fs L) /0.2} ··· ( Equation 1)
ΔR = [∂T / ∂fs] _{fs = FsL−} [∂T / ∂fs] _{fs = FsH} (Expression 2)

However, in the above (Formula 1) and (Formula 2), FsL represents the solid fraction at any one point between 0.75 ± 0.05, and FsH is between 0.95 ± 0.03. represent solid fraction of any one point, T _FSL represents the temperature when the solid phase rate is the FSL, T _FSH represents the temperature when the solid phase rate is the FSH, [∂T / ∂fs] represents a temperature change amount per unit solid phase ratio given by fs.

As described above, in the first calculation step S2, the solid phase rate is 0.95 ± 0.03 from the solid phase rate FsL at any one point when the solid phase rate of the Al alloy is between 0.75 ± 0.05. The temperature change amount ΔTii when changing to the solid phase ratio FsH at any one point in between is calculated.
The reason for this is that, as shown in FIGS. 3, 4 and 5, in the region I where the solid phase ratio of the Al alloy is 0 to less than 0.75 ± 0.05, even if a strain occurs and a gap occurs. Since there are many unsolidified liquid phases, the liquid phase is easily replenished in the generated gap, so that solidification cracks do not occur. Further, in the region III where the solid phase ratio exceeds 0.95 ± 0.03, when a strain occurs and a gap is generated, the liquid phase is not replenished to the generated gap, but the solid phases are strong and complicated. Because they are entangled, if they are less than the material strength, they will not be separated easily even if distortion due to thermal shrinkage occurs, and it becomes a restraint point. Here, the downward-sloping curve in FIG. 4 represents a liquidus line. The liquidus line is a line connecting the liquidus temperature in the liquid phase part in an equilibrium state, and the liquidus line temperature is a temperature at which the equilibrium state in the liquid phase part can be maintained. The Al alloy is completely in the solid phase at the intersection of the liquidus and the solid fraction fs1.00, and the temperature at that time is called the solidus temperature.

Therefore, in the present invention, as shown in FIG. 4, in the region II where the solid phase ratio of the Al alloy is between 0.75 ± 0.05 and 0.95 ± 0.03, the solid phase ratio is 0.75 ±. The amount of temperature change ΔTii (ΔTii = ΔTii = ΔTii = the solid phase ratio FsL at any one point between 0.05 to the solid phase ratio FsH at any one point between 0.95 ± 0.03 (T _FsL -T _FsH ) / {(Fs H -Fs L ) /0.2}) was used as an evaluation index. This is because solidification cracking easily occurs when the solid phase ratio is in this range, and it is possible to predict the difficulty of solidification cracking by grasping the behavior of the casting 8 in this range.
As the temperature change amount ΔTii is larger, the solidification cracking is easier as the value is larger, and the solidification cracking is more difficult as the value is smaller. This is because if the temperature change amount ΔTii is large, the added element is concentrated in the liquid phase, the solidification temperature is lowered, and solidification cracks are generated due to strain caused by thermal stress generated in the solid phase during the solidification process. Therefore, the temperature change amount ΔTii (Equation 1) is calculated and used as an evaluation index.

  Here, the solid phase ratio FsL is preferably 0.75 and the solid phase ratio FsH is preferably 0.95, but it is difficult to make these solid phase ratios to such numerical adjustment. In some cases, the solid phase ratio FsL has a width of ± 0.05, and the solid phase ratio FsL has a width of ± 0.03. Even if the solid phase rate FsL and the solid phase rate FsH are different from each other by providing the solid phase rate itself with a width in such a numerical range, the solid phase rate FsL and the solid phase rate By correcting with the denominator of the right term on the right side of (Equation 1) so that the width of the phase rate FsH is 1, an appropriate temperature change amount ΔTii can be calculated.

  Next, (Formula 2) will be described. As shown in FIG. 5, when the solid phase ratio is 0.75 or more, it is difficult to supply the liquid phase to the gap generated during solidification. This means that only a volume change due to heat shrinkage accompanying a temperature change occurs at a solid phase ratio higher than this. When solidifying, as shown in the left figure of FIG. 3, the portion near the surface of the cast product where the solid phase ratio in region II is near 0.95 and the inside of the cast product inside region II The portion where the solid phase ratio is in the vicinity of 0.75 is adjacent.

Since there is no difference in heat flux at the time of solidification in the adjacent portions, it is considered that the reduction in the amount of heat per unit time and unit mass in both regions II and III is equivalent.
On the other hand, the temperature change when changing from the liquid phase to the solid phase is mainly controlled by the latent heat of solidification, and the amount of solidification latent heat is proportional to the change of the solid phase rate. It is considered that the change in the solid phase ratio between the portion where the solid phase ratio is near 0.95 and the portion inside the cast product where the solid phase ratio in the region II is near 0.75 is the same speed.

Even if the same solid phase ratio change occurs, the temperature drop amount is higher in the portion where the solid phase ratio in the region II is near 0.95 than in the portion where the solid phase ratio in the region II is near 0.75. Becomes larger. That is, as shown in the lowermost diagram in the right diagram of FIG. 3, the portion where the solid phase ratio in the region II is in the vicinity of 0.95 has a larger thermal shrinkage and is more likely to be solidified.
In addition, as the difference in thermal shrinkage between the portion where the solid phase ratio in the region II is near 0.75 and the portion where the solid phase ratio in the region II is near 0.95 is larger, In the region II where the solid phase ratio is large, the portion where the solid phase ratio is near 0.95 (the one closer to the surface of the cast product) is more likely to be solidified.

Therefore, in the present invention, as shown in FIG. 4, when the solid phase ratio fs of the Al alloy is FsL, that is, the above-mentioned solid phase ratio is any one of 0.75 ± 0.05. When the solid phase rate fs of the Al alloy is FsH, that is, the temperature change amount when the solid phase rate is any one point between 0.95 ± 0.03. The larger the difference ΔR, the easier the solidification cracking, and the smaller the difference ΔR, the less the solidification cracking. Therefore, the difference ΔR (ΔR = [∂T / ∂fs] _{fs = FsL−} [∂T / ∂fs] _{fs = FsH} ) is used as an evaluation index. The temperature change amount when the solid phase ratio fs is any one point between 0.75 ± 0.05 is expressed by [さ れ T / ∂fs] _{fs = FsL} in (Expression 2), The temperature change amount when the rate fs is any one point between 0.95 ± 0.03 is represented by [∂T / ∂fs] _{fs = FsH} in (Expression 2).

  Note that (Equation 1) and (Equation 2) in the first calculation step S2 described above can be calculated before (Equation 3) in the second calculation step S3 to be described later. May be.

In the subsequent second calculation step S3, based on the following (Expression 3), the difference ΔR calculated in the (Expression 2), the casting speed v (mm / min), and the temperature change amount ΔTii calculated in the (Expression 1). Is calculated.
ΔR / ΔTii <1020 × ΔTii / v ² (Formula 3)
However, in said (Formula 3), v represents a casting speed (mm / min).

  The ΔR / ΔTii (hereinafter sometimes referred to as “solid phase ratio temperature gradient change amount”) on the left side of the following (Equation 3) calculated in this way is more likely to cause solidification cracking as the value increases. It is a little inside the solidified part with a high solid fraction, when the solid part with a low solid fraction and a high temperature becomes a restraint part and the inside solidifies, the solidified part with the high solid fraction is This is because the heat shrinkage is hindered, and solidification cracking occurs in the solidified portion having a high solid phase ratio due to the heat shrinkage. This is a phenomenon often seen in surface cracks. For this reason, surface cracks may be targeted as solidification cracks predicted by (Equation 3).

  The difficulty of solidification cracking of the casting 8 is also affected by the casting speed v. Specifically, as the casting speed v increases, the solidified layer becomes thinner as the speed increases, and the adjacent region II having a low solid fraction and the region III having a high solid fraction approach each other. Strain accumulates in the higher region III (closer to the surface of the cast product), and solidification cracking is likely to occur.

  The difference in strain can be expressed by ΔR. However, since the thickness of the solidified layer varies depending on the alloy, the thickness of the solidified layer having a solid phase ratio of 0.75 to 0.95 varies. In addition, since the sensitivity to solidification cracks decreases in proportion to the increase in the thickness of the solidified layer, the sensitivity to solidification cracks can be normalized by dividing by ΔTii that can express the solidification thickness. The evaluation index of solidification cracking susceptibility by the normalized alloy component can be expressed by the left side of (Equation 3).

On the other hand, the susceptibility to casting cracks associated with changes in casting conditions can be expressed by the magnitude of “shrinkage” that occurs during solidification. “Short” is more likely to occur because the solid-liquid coexistence region becomes larger as the temperature gradient G [K / m] is larger, and the larger solid-liquid coexistence region remains as the solidification progress velocity V _C [m / s] increases. Since solidification proceeds as it is, “shrinking” is likely to occur. Therefore, the larger G / V _{C, the} easier it is for solidification cracks to occur.

Since the temperature gradient G can be obtained by dividing the cooling rate r [K / s] by the solidification progress rate V _C , it can be expressed as G / V _C = r / V _C ² .
Since the temperature change amount ΔTii means that the larger the value, the lower the temperature when the same heat is taken away, the cooling rate r increases, and the cooling rate r and ΔTii have a proportional relationship. Further, since the solidification progress speed V _C and the casting speed v are also proportional, G / V _C = r / V _C ² ∝ΔTii / v ² .

From the above, the ease of “shrinking”, that is, the susceptibility to solidification cracking accompanying the casting conditions can be expressed by ΔTii / v ² (the right side of (Equation 3)), and by comparing both sides with a constant constant. It becomes possible to judge the difficulty of solidification cracking. The constant is 1020. Since the constant is determined experimentally, this will be described later.
Therefore, it is determined whether or not ΔR / ΔTii satisfies ΔTii / v ² and satisfies the specific relationship shown in (Formula 3), thereby casting an Al alloy casting 8 having a desired composition component. The difficulty of solidification cracking at the time can be predicted.

In the subsequent prediction step S4, it is predicted that solidification cracking is difficult when the relationship between the calculated difference ΔR, casting speed v (mm / min), and temperature change amount ΔTii satisfies the above (Equation 3).
This is because when the relationship between the calculated difference ΔR, casting speed v (mm / min), and temperature change amount ΔTii satisfies (Equation 3), the Al alloy is sensitive to casting cracks due to changes in casting conditions. This is because it is considered to be low and it is possible to predict that solidification cracking is difficult. On the other hand, when these relationships do not satisfy the above (Equation 3), the Al alloy is considered to be highly sensitive to casting cracks due to changes in casting conditions, and therefore it is possible to predict that it is likely to be solidified cracks. Because it becomes.

  In the output step S5, the result of the prediction in the prediction step S4, that is, the type and addition amount of the added additive element, and the casting speed were semi-continuously cast by the vertical direct water cooling method at the casting speed. Outputs to the monitor, printer, etc. whether solidification cracking is difficult during the solidification process.

As the casting 8 of the Al alloy that is the subject of the present invention, for example, a continuous casting ingot such as a billet, slab, or ingot manufactured by a casting process is applicable.
Examples of the Al alloy used include an Al—Si alloy, an Al—Mg alloy, an Al—Cu alloy, an Al—Mn alloy, an Al—Si—Mg alloy, and an Al—Si—Cu alloy. Can be mentioned.

The solidification process at the time of solidification may be either by slow cooling such as natural cooling or by rapid cooling such as water cooling.
In addition, examples of the solidification cracks to be targeted include surface cracks that occur on the surface of a cast product.

  The relationship between the solid phase ratio and the temperature may be obtained by measurement by thermal analysis or the like. However, as described above, the temperature when the solid phase ratio is 0.75 and the solid phase ratio is 0.95. Since it is difficult to measure the temperature strictly, it is preferable to use a general-purpose thermodynamic database such as a thermocalc. However, since it is necessary to consider the change in the solid phase ratio accompanying solidification, it is preferable to utilize the Scheil equation or the Scheil module, which is a liquid phase complete mixing model (non-diffusion model in solid phase).

  Scheil's formula shows the difficulty of solidification cracking when casting a casting of an Al alloy of a binary system or lower such as an Al-Si alloy, Al-Mg alloy, Al-Cu alloy, Al-Mn alloy. This is suitable for prediction. The Scheil module is suitable for predicting the difficulty of solidification cracking when casting a ternary or higher Al alloy casting such as an Al-Si-Mg alloy or Al-Si-Cu alloy. . Of course, the Scheil module can also predict the difficulty of solidification cracking when casting an Al alloy casting of a binary system or lower.

Scheil's formula is shown in (Formula 4) and (Formula 5) below.
k = C _S / C _L (Formula 4)
(However, in (Formula 4), k represents a solid-liquid partition coefficient, C _S represents a solute concentration in the solid phase, and C _L represents a solute concentration in the liquid phase.)

By substituting this into the following (formula 5), the solute concentration in the liquid phase is obtained.
C _L = C ₀ × (1−fs) ^(k−1) (Formula 5)
(However, in (Formula 5), C _L is the solute concentration in the liquid phase, C ₀ is the solute concentration in the initial liquid phase, fs is the solid phase ratio, and k is the solid-liquid partition coefficient.)

Then, the liquidus temperature of the solute concentration C _L in the liquid phase obtained in (Equation 5) is obtained from the general thermodynamic databases such Samokaruku. Thus, from said liquidus temperature in solute concentration C _L in the liquid phase obtained in (Equation 5), such as by referring to the graph shown in FIG. 4, the relation between the solid fraction fs and temperature It is possible to ask. Such a calculation method can be suitably applied when diffusion is negligible as in rapid solidification. For example, it is more preferable that the relationship between the solid phase ratio and the temperature can be obtained by the difference method described in JP-A-2005-62108.

In addition, the Scheil module adds a part of the liquid phase changed to a solid phase when the temperature is lowered by 1 ° C based on the data recorded in the general-purpose thermodynamic database. The temperature T _FsL when the solid phase ratio is in the vicinity of FsL (for example, the range of the solid phase ratio FsL ± 0.01) is formed by repeatedly forming a liquid phase with a concentration and decreasing the temperature _again . This is a technique for calculating the change and the change in temperature T _FsH when the solid phase ratio is in the vicinity of FsH (for example, the range of solid phase ratio FsH ± 0.01).

  The solidification crack prediction method according to the present invention is as described above. However, in carrying out the present invention, other steps may be included within a range that does not adversely affect each of the steps described above. For example, between the first calculation step S2 and the prediction step S4, the calculation result in each step is stored in the storage means 13 (see FIGS. 7 and 8) described later, the stored calculation result, and the necessary information described above Or a memory read step for reading. In addition, during the execution of the first calculation step S2 to the prediction step S4, a key input for arbitrarily stopping or temporarily stopping the calculation is accepted, and a stop step for stopping the calculation in each step or a temporary pause A stop step or the like can be included.

The solidification crack prediction method according to the present invention described above can be suitably applied to a casting method for casting an Al alloy casting.
As shown in FIG. 6, the casting method for casting an Al alloy casting using the solidification crack prediction method according to the present invention includes an input step S11, a storage step S15, a first calculation step S2, and a second calculation. In the case where it is predicted that solidification cracking is difficult in prediction step S4, including the step S3, prediction step S4, resetting step S6, and re-execution step S7, the additive element predicted to be difficult to solidify cracking The casting is cast at the type, amount added, and casting speed.
Here, the casting conditions for casting the cast product can be applied without any problem as long as they are normally performed.

  In the casting method using the solidification crack prediction method according to the present invention, the first calculation step S2, the second calculation step S3, and the prediction step S4 are the first of the solidification crack prediction method according to the present invention already described in detail. Since this is the same as the calculation step S2, the second calculation step S3, and the prediction step S4, redundant description thereof will be omitted.

The input step S11 is a step of inputting the kind of additive element that can be added to the Al alloy, the desired addition amount, the numerical range of the allowable addition amount of the additive element, the casting speed, and the numerical range of the allowable speed of the casting speed. is there. Incidentally, in that what is input is obtained by the inputs forming rate contents inputted cast, different from the input step S1 of the solidification cracking prediction method. The allowable addition amount of the additive element refers to the addition amount that can be added to the Al alloy, and the allowable speed of casting speed refers to the speed that is allowable as the casting speed of the cast product. The cross-sectional area is an allowable cross-sectional area for a cast product.

  The storage step S15 is a step of storing the kind of additive element that can be added to the Al alloy input in the input step S11, the numerical range of the allowable addition amount of the additive element, and the numerical range of the allowable speed of the casting speed. .

  In the resetting step S6, when it is predicted that the solidification crack is likely to occur in the prediction step S4, the type of the additive element, the numerical value of the additive element addition amount, and the casting speed are stored in the storage step S15. It is a step of resetting within the numerical range of the allowable addition amount of the additive element and within the numerical range of the allowable speed of the casting speed.

  The resetting is performed by resetting the casting speed and executing the re-execution step S7 described later, resetting the addition amount of the additive element and executing the re-execution step S7 described later, resetting the type of the additive element, It is preferable to perform in order of execution step S7. In this way, it is possible to reduce the contents of change from the desired alloy components and the extent thereof.

  For the resetting of the casting speed, the numerical value is sequentially decreased or increased by the minimum numerical unit that can be changed from the maximum value or the minimum value within the numerical range of the allowable speed of the casting speed stored in the storage step S15, and the contents are sequentially changed. The first calculation step S2, the second calculation step S3, and the prediction step S4 may be repeatedly executed.

  The resetting of the addition amount of the additive element is performed in the minimum numerical unit that can be changed from the maximum value or the minimum value within the numerical range of the allowable addition amount of the additive element that can be added to the Al alloy stored in the storage step S15. The numerical value may be decreased or increased sequentially, and the first calculation step S2, the second calculation step S3, and the prediction step S4 described above may be repeatedly executed according to the contents.

The resetting of the type of the additive element is reset within the type of the additive element that can be added to the Al alloy stored in the storage step S15, and the maximum allowable addition amount set for the reset element is within the numerical value. From the value or the minimum value, the numerical value may be sequentially decreased or increased by a changeable minimum numerical unit, and the first calculation step S2, the second calculation step S3, and the prediction step S4 described above may be repeatedly executed sequentially with the contents. .
The types of additive elements that can be added to the Al alloy are ranked, for example, as a first candidate, a second candidate, etc., and are reset by replacing or adding the additive element according to the order. Is preferred. Here, it is preferable that substitution and addition of additive elements can be arbitrarily set. In this way, for example, from an Al—Mn alloy to an Al—Mg alloy, from an Al—Mg alloy to an Al—Mn alloy, or from an Al—Si—Mg alloy to Al—Si—Cu. An additive element can be substituted such as an Al alloy or an Al-Si-Cu alloy to an Al-Si-Mg alloy. Further, for example, an additive element can be added from an Al—Mg alloy to an Al—Si—Mg alloy.

If a prediction result indicating that solidification cracking is difficult is obtained in the prediction step S4, the result may be output to stop the casting method according to the present invention using the solidification crack prediction method according to the present invention. .
The minimum numerical unit that can be changed can be arbitrarily set depending on the device used for the calculation and the software installed in the device. For example, 0.0001 mass% or 0.001 mass% for the allowable addition amount. 0.01% by mass or the like, and if the casting speed is acceptable, it can be 1 mm / min, 0.1 mm / min, or the like.

  The resetting sequence in the resetting step S6 described above is performed when the parameters to be reset are three types of additive element type, additive element addition amount, and casting speed. The casting speed is reset with the addition amount fixed, but the resetting order in the resetting step S6 is not limited to this. For example, the additive element type and casting speed may be fixed and the additive element addition amount reset, or the additive element addition amount and casting speed fixed and the additive element type reset. May be. The order of resetting can be arbitrarily determined.

  In this way, the resetting step S6 can be suitably performed, and it becomes possible to prevent casting of a cast product in which solidification cracking, particularly surface cracking has occurred. As a result, productivity reduction and loss can be eliminated.

  The subsequent re-execution step S7 is a step of re-execution from the first calculation step S2 described above with the content reset in the reset step S6.

  In addition, since the casting method according to the present invention can be controlled by the casting speed in addition to the alloy composition, the casting method using the Al alloy is applied to a case where semi-continuous casting (DC casting) is performed. be able to. In other words, by changing the constant such as 1020 in (Equation 3), the relational expression of (Equation 3) can be applied to continuous casting such as twin rolls, twin belts, and Properti, and castings such as molds and sand molds. The casting method according to the present invention can be applied. Constants in continuous casting and constants in castings such as molds and sand molds may be obtained by experiments.

  Next, a solidification crack prediction apparatus and a solidification crack prediction program according to the present invention will be described with reference to FIGS. Note that the detailed description of the contents already described in detail, such as (Expression 1) to (Expression 3), is omitted in order to avoid redundant description.

As shown in FIG. 7, the solidification crack prediction apparatus 10 according to an embodiment is a so-called computer, and mainly includes an input unit 11, a control unit 12, a storage unit 13, and an output unit 14.
The input means 11 is, for example, a keyboard for inputting letters and numbers, whereby the types of additive elements that can be added to the Al alloy (that is, the components of the Al alloy), the added amount, and the allowable added amount of the added element Such information as numerical range, casting speed, and numerical range of allowable speed of the casting speed can be input to the computer.

The control unit 12 includes a so-called CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), and the like, and performs various numerical calculations, information processing, device control, and the like by a program. Can do.
Therefore, according to the program, the control unit 12 causes the solid phase rate to be zero from the solid phase rate FsL at any one point between the solid phase rates of the Al alloy based on the above (Formula 1) between 0.75 ± 0.05. .Calculation of temperature change amount ΔTii when changing to solid phase rate FsH at any one point between 95 ± 0.03, and when solid phase rate of Al alloy is FsL based on (Equation 2) Based on the first calculation means 121 for calculating the difference ΔR between the temperature change amount per unit solid phase rate and the temperature change amount per unit solid phase rate when the solid phase rate is FsH, based on the above (Formula 3). Second difference calculating means 122 for calculating the relationship between the calculated difference ΔR, the calculated temperature change amount ΔTii and the casting speed v (mm / min), the calculated difference ΔR, the calculated temperature change amount ΔTii and When the relationship of the casting speed v (mm / min) satisfies the above (Formula 3) Solid cracking hardly and it is possible for causing a computer to function as the prediction unit 123 for predicting, may be the computer as solidification cracking prediction apparatus 10.

The storage means 13 is, for example, an information recording medium such as an HDD (hard disk drive), a program for calculating the above (Equation 1), (Equation 2), and (Equation 3), a first calculation means 121, Various types of information necessary for the execution of the second calculating means 122 and the predicting means 123, for example, the type of additive element that can be added to the Al alloy, the desired addition amount, and the casting speed, and the calculation obtained by these. Results and the like can be stored and read as necessary.
The output means 14 is, for example, a monitor, a printer, or the like. The result of the difficulty of solidification cracking on the screen or the paper, the calculation result in (Expression 1) to (Expression 3), and the type of additive element that is difficult to solidify cracking. The addition amount and casting speed can be displayed as necessary.

Further, as shown in FIG. 8, the solidification crack prediction device 20 according to another embodiment is also a so-called computer, and mainly includes an input unit 11, a control unit 22, a storage unit 13, and an output unit 14. .
The input unit 11 and the output unit 14 are the same as those of the solidification crack prediction apparatus 10 according to the embodiment, and thus the description thereof will be omitted, and the control unit 22 will be mainly described.

  The storage means 13 in the solidification crack prediction apparatus 20 includes a program for calculating the above-described (Expression 1), (Expression 2), and (Expression 3), first calculation means 221 and second calculation means described later. 222, necessary for execution of the predicting means 223 and the resetting means 224, for example, the kind of additive element that can be added to the Al alloy and the desired additive amount, the numerical range of the allowable additive amount of the additive element, the casting speed, and Various information such as the numerical range of the allowable speed of the casting speed can be arbitrarily read out by storing in advance before executing the program. Further, the calculation result obtained by executing the program can be stored or read as necessary, and the kind and amount of additive element reset by the resetting means 224 described later, and It is possible to memorize and read the casting speed.

  And the control part 22 is comprised by what is called CPU, RAM, ROM etc. like the above-mentioned control part 12. FIG. Therefore, according to the program, the control unit 22 causes the solid phase ratio to be zero from the solid phase ratio FsL at any one point between the solid phase ratios of the Al alloy based on (Formula 1) between 0.75 ± 0.05. .Calculation of temperature change amount ΔTii when changing to solid phase rate FsH at any one point between 95 ± 0.03, and when solid phase rate of Al alloy is FsL based on (Equation 2) Based on the first calculation means 221 that calculates the difference ΔR between the temperature change amount per unit solid phase rate and the temperature change amount per unit solid phase rate when the solid phase rate is FsH, based on the above (Formula 3). Second difference calculating means 222 for calculating the relationship between the calculated difference ΔR, the calculated temperature change amount ΔTii and the casting speed v (mm / min), the calculated difference ΔR, the calculated temperature change amount ΔTii and the When the relationship of the casting speed v (mm / min) satisfies the above (Formula 3), Predicting means 223 that predicts that solidification cracks are likely to occur when these relations do not satisfy the above (Equation 3), and if the prediction means 223 predicts that solidification cracks are likely to occur, the additive element Of the additive element, the numerical value of the additive element addition amount, and the casting speed stored in the storage means 13 in advance as described above, within the additive element type that can be added to the Al alloy, and the allowable additive element addition amount Resetting means 224 for resetting within the numerical range of the casting speed and within the numerical range of the permissible casting speed, and resetting from the first calculating means 221 to the predicting means 223 with the contents reset by the resetting means 224. A computer can function as the re-execution means 225 to be executed, and the computer can be used as the solidification crack prediction device 20.

  The resetting performed by the resetting means 224 may be performed in the same order and contents as the resetting step S6 described in the casting method for casting an Al alloy cast using the solidification crack prediction method according to the present invention. Therefore, detailed description is omitted.

Next, examples in which the effects of the present invention have been confirmed will be described.
In order to verify the solidification cracks observed in the solidification process when casting an Al alloy casting, an Al alloy having an alloy number of (1) to (12) having the alloy composition shown in Table 1 was used.

  And, according to the casting conditions of A to C shown in the following Table 2 and the Al alloys having the alloy numbers of (1) to (12), Nos. Test pieces according to 1 to 17 were produced.

In addition, as shown in Table 3, No. The casting results (presence / absence of solidification cracking) of the test pieces according to 1 to 17 were confirmed by color-checking the surface.
For the color check, a microcheck cleaning solution, a microcheck penetrating solution (red solution), and a microcheck developer (white) manufactured by KOHZAI were used. Specifically, after cleaning the surface with a microcheck cleaning solution, spray the microcheck penetrating solution (red solution) to infiltrate, rewash with the microcheck cleaning solution, and then spray the microcheck developer (white). This was done by visual observation. It was judged that a solidification crack (surface crack) occurred when the penetrant was stained red by visual observation. The casting results (presence of solidification cracking) are shown in Table 3 together with the alloy number and casting conditions. Those in which solidification cracks did not occur were indicated as “O” as acceptable, and those in which solidification cracks occurred were indicated as “x” as unacceptable.

  Further, as shown in FIGS. 9A to 9C, it can be seen that solidification cracking occurs in the low-speed casting as the alloy has a larger temperature variation ΔTii and solid phase ratio temperature gradient variation ΔR / ΔTii. Moreover, it turns out that the area | region which does not solidify and crack is so wide as low speed casting. In the figure, the horizontal axis represents the temperature change amount ΔTii [° C.], and the vertical axis represents the solid phase ratio temperature gradient change amount ΔR / ΔTii.

As shown in FIGS. 9 (a) to 9 (c), no. No. 1-8 test pieces and No. in which solidification cracking occurred. When the relationship with the test pieces of 9 to 17 was examined using the thermodynamic database Thermo-calc (manufactured by CRC Research Institute), the solid fraction of each Al alloy was 0.75 (that is, the solid fraction FsL). Temperature change amount ΔTii when the solid phase ratio changes from 0.95 to 0.95 (that is, solid phase ratio FsH), and temperature change amount per unit solid phase ratio when the solid phase ratio of each Al alloy is 0.75 And ΔR between the change in temperature per unit solid phase ratio when the solid phase ratio is 0.95 was calculated. Then, it was analyzed them were found to be strongly correlated to 1020 × value of ΔTii / v ² to be compared with ΔR / ΔTii. The results are also shown in Table 3 above.

As shown in Table 3, no. For 1 to 8, it was found that the relationship of ΔR / ΔTii <1020 × ΔTii / v ² is established, and that it can be said that it is difficult to break as a prediction result.
On the other hand, no. Regarding 9 to 17, it was found that the relationship of ΔR / ΔTii <1020 × ΔTii / v ² does not hold and it can be said that the prediction result is easy to break.

  The solidification crack prediction method, the casting method using the solidification crack prediction apparatus, the solidification crack prediction apparatus, and the solidification crack prediction program according to the present invention have been specifically described with reference to the embodiments and examples for carrying out the invention. The gist of the invention is not limited to these descriptions, and the scope of rights should be broadly interpreted based on the description of the claims. Further, those skilled in the art can easily change or modify the solidification crack prediction method of the present invention, a casting method using the same, and solidification based on the description of the embodiments and examples for carrying out the invention of the present specification. A method and apparatus equivalent to a crack prediction device and a solidification crack prediction program can be obtained, and such a solidification crack prediction method of the present invention, a casting method using the same, a solidification crack prediction device, and a solidification crack prediction Included in the program.

S1, S11 Input step S15 Storage step S2 First calculation step S3 Second calculation step S4 Prediction step S5 Output step S6 Resetting step S7 Re-execution step 1 DC casting apparatus 2 Molten metal 3 Launder 4 Hot water surface control system 5 Mold 6 Bottom block 7 Cooling water 8 Casting product
I, II, III area

Claims (8)

A solidification crack prediction method for predicting the difficulty of solidification cracking seen in the solidification process when semi-continuous casting of an Al alloy cast product by vertical direct water cooling,
An input step of inputting a forming speed casting,
Based on the following (Equation 1), the solid fraction of the Al alloy is between 0.75 ± 0.05 and the solid fraction is between 0.95 ± 0.03 from the solid fraction FsL at any one point. The temperature per unit solid fraction when the solid fraction of the Al alloy is FsL based on the calculation of the temperature change amount ΔTii when changing to the solid fraction FsH at any one point in FIG. A first calculation step of calculating a difference ΔR between a change amount and a temperature change amount per unit solid phase rate when the solid phase rate is FsH;
A second calculation step of calculating a relationship among the calculated difference ΔR, the calculated temperature change amount ΔTii, and the input casting speed v (mm / min) based on the following (Equation 3):
A prediction step of predicting that solidification cracking is difficult when the relationship between the calculated difference ΔR, the calculated temperature change amount ΔTii, and the input casting speed v (mm / min) satisfies the following (Equation 3);
An output step of outputting a result predicted by the prediction step;
The solidification cracking prediction method characterized by including this.
_{ΔTii = (T FsL -T FsH)} / {(Fs H -Fs L) /0.2} ··· ( Equation 1)
ΔR = [∂T / ∂fs] _{fs = FsL−} [∂T / ∂fs] _{fs = FsH} (Expression 2)
ΔR / ΔTii <1020 × ΔTii / v ² (Formula 3)
(However, in the above (Formula 1) to (Formula 3),
FsL represents the solid fraction at any one point between 0.75 ± 0.05,
FsH represents the solid fraction at any one point between 0.95 ± 0.03,
T _FsL represents the temperature when the solid phase ratio is FsL,
T _FsH represents the temperature when the solid phase ratio is the FsH,
[∂T / ∂fs] represents the amount of temperature change per unit solid phase ratio given by fs,
v represents a casting speed (mm / min). ) When calculating the temperature change ΔTii using a general-purpose thermodynamic database,
If the Al alloy is binary or more Al alloy, and the temperature T _{Fs L} when the solid fraction of the FsL using Scheil module is in the liquid phase complete mixing model of the thermodynamic database, the solidification cracking prediction method according to claim 1, characterized in that the solid phase ratio to calculate the temperature change amount ΔTii seeking the temperature T _{Fs H,} the time of the FSH.   The solidification crack prediction method according to claim 1, wherein the solidification crack is a surface crack. A casting method for casting an Al alloy casting using the solidification crack prediction method according to any one of claims 1 to 3,
An input step for inputting the kind and amount of additive element that can be added to the Al alloy, the numerical range of the allowable addition amount of the additive element, the casting speed, and the numerical range of the allowable speed of the casting speed;
A storage step for storing the type of additive element that can be added to the Al alloy input in the input step, the numerical range of the allowable addition amount of the additive element, and the numerical range of the allowable speed of the casting speed; ,
Based on the following (Equation 1), the solid fraction of the Al alloy is between 0.75 ± 0.05 and the solid fraction is between 0.95 ± 0.03 from the solid fraction FsL at any one point. The temperature per unit solid fraction when the solid fraction of the Al alloy is FsL based on the calculation of the temperature change amount ΔTii when changing to the solid fraction FsH at any one point in FIG. A first calculation step of calculating a difference ΔR between a change amount and a temperature change amount per unit solid phase rate when the solid phase rate is FsH;
A second calculation step of calculating a relationship among the calculated difference ΔR, the calculated temperature change amount ΔTii, and the input casting speed v (mm / min) based on the following (Equation 3):
When the relationship between the calculated difference ΔR, the calculated temperature change amount ΔTii, and the casting speed v (mm / min) satisfies the following (Equation 3), it is predicted that solidification cracking is difficult, and these relationships are as follows ( A prediction step for predicting that solidification cracking is likely to occur when Equation 3) is not satisfied;
When it is predicted that the solidification cracking is likely in the prediction step, the type of the additive element, the numerical value of the addition amount of the additive element, and the casting speed are stored in the storage step, the type of the additive element, the addition A resetting step for resetting within the numerical range of the allowable addition amount of the element and within the numerical range of the allowable speed of the casting speed;
A re-execution step for re-execution from the first calculation step with the content reset in the reset step,
When it is predicted that solidification cracking is difficult in the prediction step, a casting product is cast at the type and addition amount of the additive element predicted to be difficult to solidify cracking, and at a casting speed.
_{ΔTii = (T FsL -T FsH)} / {(Fs H -Fs L) /0.2} ··· ( Equation 1)
ΔR = [∂T / ∂fs] _{fs = FsL−} [∂T / ∂fs] _{fs = FsH} (Expression 2)
ΔR / ΔTii <1020 × ΔTii / v ² (Formula 3)
(However, in the above (Formula 1) to (Formula 3),
FsL represents the solid fraction at any one point between 0.75 ± 0.05,
FsH represents the solid fraction at any one point between 0.95 ± 0.03,
T _FsL represents the temperature when the solid phase ratio is FsL,
T _FsH represents the temperature when the solid phase ratio is the FsH,
[∂T / ∂fs] represents the amount of temperature change per unit solid phase ratio given by fs,
v represents a casting speed (mm / min). ) A solidification crack prediction device for predicting the difficulty of solidification cracking seen in the solidification process when semi-continuous casting of an Al alloy cast product by a vertical direct water cooling method,
Input means for inputting the elephant rate cast,
Based on the following (Equation 1), the solid fraction of the Al alloy is between 0.75 ± 0.05 and the solid fraction is between 0.95 ± 0.03 from the solid fraction FsL at any one point. The temperature per unit solid fraction when the solid fraction of the Al alloy is FsL based on the calculation of the temperature change amount ΔTii when changing to the solid fraction FsH at any one point in FIG. A first calculating means for calculating a difference ΔR between a change amount and a temperature change amount per unit solid phase rate when the solid phase rate is FsH;
Based on the following (Equation 3), a second calculation means for calculating the relationship between the calculated difference ΔR, the calculated temperature change amount ΔTii, and the input casting speed v (mm / min);
A predicting means for predicting that solidification cracking is difficult when the relationship between the calculated difference ΔR, the calculated temperature change amount ΔTii, and the input casting speed v (mm / min) satisfies the following (Equation 3);
Output means for outputting the result predicted by the prediction means;
A solidification crack prediction device characterized by comprising:
_{ΔTii = (T FsL -T FsH)} / {(Fs H -Fs L) /0.2} ··· ( Equation 1)
ΔR = [∂T / ∂fs] _{fs = FsL−} [∂T / ∂fs] _{fs = FsH} (Expression 2)
ΔR / ΔTii <1020 × ΔTii / v ² (Formula 3)
(However, in the above (Formula 1) to (Formula 3),
FsL represents the solid fraction at any one point between 0.75 ± 0.05,
FsH represents the solid fraction at any one point between 0.95 ± 0.03,
T _FsL represents the temperature when the solid phase ratio is FsL,
T _FsH represents the temperature when the solid phase ratio is the FsH,
[∂T / ∂fs] represents the amount of temperature change per unit solid phase ratio given by fs,
v represents a casting speed (mm / min). ) A solidification crack prediction device for predicting the difficulty of solidification cracking seen in the solidification process when semi-continuous casting of an Al alloy cast product by a vertical direct water cooling method,
Input means for inputting the kind and amount of additive element that can be added to the Al alloy, the numerical range of the allowable addition amount of the additive element, the casting speed, and the numerical range of the allowable speed of the casting speed;
Storage means for storing the kind of additive element that can be added to the Al alloy inputted by the input means, the numerical range of the allowable addition amount of the additive element, and the numerical range of the allowable speed of the casting speed; ,
Based on the following (Equation 1), the solid fraction of the Al alloy is between 0.75 ± 0.05 and the solid fraction is between 0.95 ± 0.03 from the solid fraction FsL at any one point. The temperature per unit solid fraction when the solid fraction of the Al alloy is FsL based on the calculation of the temperature change amount ΔTii when changing to the solid fraction FsH at any one point in FIG. A first calculating means for calculating a difference ΔR between a change amount and a temperature change amount per unit solid phase rate when the solid phase rate is FsH;
Based on the following (Equation 3), a second calculation means for calculating the relationship between the calculated difference ΔR, the calculated temperature change amount ΔTii, and the input casting speed v (mm / min);
When the relationship between the calculated difference ΔR, the calculated temperature change amount ΔTii, and the casting speed v (mm / min) satisfies the following (Equation 3), it is predicted that solidification cracking is difficult, and these relationships are as follows ( A predicting means for predicting that solidification cracking is likely to occur when Equation 3) is not satisfied;
When it is predicted that the prediction means is likely to cause solidification cracking, the type and addition amount of the additive element, and the casting speed, the type of additive element stored in the storage means, and the allowable addition amount of the additive element Resetting means for resetting within the numerical range of the above, and within the numerical range of the allowable speed of the casting speed,
Re-execution means for re-execution from the first calculation means with the contents reset by the resetting means;
Output means for outputting the result predicted by the prediction means;
A solidification crack prediction device characterized by comprising:
_{ΔTii = (T FsL -T FsH)} / {(Fs H -Fs L) /0.2} ··· ( Equation 1)
ΔR = [∂T / ∂fs] _{fs = FsL−} [∂T / ∂fs] _{fs = FsH} (Expression 2)
ΔR / ΔTii <1020 × ΔTii / v ² (Formula 3)
(However, in the above (Formula 1) to (Formula 3),
FsL represents the solid fraction at any one point between 0.75 ± 0.05,
FsH represents the solid fraction at any one point between 0.95 ± 0.03,
T _FsL represents the temperature when the solid phase ratio is FsL,
T _FsH represents the temperature when the solid phase ratio is the FsH,
[∂T / ∂fs] represents the amount of temperature change per unit solid phase ratio given by fs,
v represents a casting speed (mm / min). ) A solidification crack prediction program for predicting the difficulty of solidification cracking seen in the solidification process when semi-continuous casting of an Al alloy casting is performed by a vertical direct water cooling method,
Computer
Based on the following (Equation 1), the solid fraction of the Al alloy is between 0.75 ± 0.05 and the solid fraction is between 0.95 ± 0.03 from the solid fraction FsL at any one point. The temperature per unit solid fraction when the solid fraction of the Al alloy is FsL based on the calculation of the temperature change amount ΔTii when changing to the solid fraction FsH at any one point in FIG. A first calculating means for calculating a difference ΔR between a change amount and a temperature change amount per unit solid phase rate when the solid phase rate is FsH;
Based on the following (Formula 3), the calculated difference ΔR, the calculated temperature change amount ΔTii and the second calculating means for calculating the relationship between the casting speed v (mm / min), and the calculated difference ΔR A solidification crack prediction program that functions as prediction means for predicting that solidification cracking is difficult when the relationship between the temperature change amount ΔTii and the casting speed v (mm / min) satisfies the following (Equation 3).
_{ΔTii = (T FsL -T FsH)} / {(Fs H -Fs L) /0.2} ··· ( Equation 1)
ΔR = [∂T / ∂fs] _{fs = FsL−} [∂T / ∂fs] _{fs = FsH} (Expression 2)
ΔR / ΔTii <1020 × ΔTii / v ² (Formula 3)
(However, in the above (Formula 1) to (Formula 3),
FsL represents the solid fraction at any one point between 0.75 ± 0.05,
FsH represents the solid fraction at any one point between 0.95 ± 0.03,
T _FsL represents the temperature when the solid phase ratio is FsL,
T _FsH represents the temperature when the solid phase ratio is the FsH,
[∂T / ∂fs] represents the amount of temperature change per unit solid phase ratio given by fs,
v represents a casting speed (mm / min). ) A solidification crack prediction program for predicting the difficulty of solidification cracking seen in the solidification process when semi-continuous casting of an Al alloy casting is performed by a vertical direct water cooling method,
Computer
Based on the following (Equation 1), the solid fraction of the Al alloy is between 0.75 ± 0.05 and the solid fraction is between 0.95 ± 0.03 from the solid fraction FsL at any one point. The temperature per unit solid fraction when the solid fraction of the Al alloy is FsL based on the calculation of the temperature change amount ΔTii when changing to the solid fraction FsH at any one point in FIG. A first calculating means for calculating a difference ΔR between a change amount and a temperature change amount per unit solid phase rate when the solid phase rate is FsH;
A second calculating means for calculating a relationship between the calculated difference ΔR, the calculated temperature change amount ΔTii, and the casting speed v (mm / min) based on the following (formula 3):
When the relationship between the calculated difference ΔR, the calculated temperature change amount ΔTii, and the casting speed v (mm / min) satisfies the following (Equation 3), it is predicted that solidification cracking is difficult, and these relationships are as follows ( A predicting means for predicting that solidification cracking is likely to occur when Equation 3) is not satisfied;
Wherein when it is predicted crack Shi easily and solidified in predicting means, the addition amount and type of added pressure element, and the casting speed, the type of the additional element that has been stored in advance in the storage unit, allowable of the additive element Resetting means for resetting within the numerical range of the addition amount and within the numerical range of the allowable speed of the casting speed, and re-execution means for re-execution from the first calculation means with the content reset by the resetting means Solidification crack prediction program characterized by making it function.
_{ΔTii = (T FsL -T FsH)} / {(Fs H -Fs L) /0.2} ··· ( Equation 1)
ΔR = [∂T / ∂fs] _{fs = FsL−} [∂T / ∂fs] _{fs = FsH} (Expression 2)
ΔR / ΔTii <1020 × ΔTii / v ² (Formula 3)
(However, in the above (Formula 1) to (Formula 3),
FsL represents the solid fraction at any one point between 0.75 ± 0.05,
FsH represents the solid fraction at any one point between 0.95 ± 0.03,
T _FsL represents the temperature when the solid phase ratio is FsL,
T _FsH represents the temperature when the solid phase ratio is the FsH,
[∂T / ∂fs] represents the amount of temperature change per unit solid phase ratio given by fs,
v represents a casting speed (mm / min). )

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