JPH083139B2 - Method for manufacturing thick and complex heat-treating aluminum alloy member - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention uses a heat treatment type aluminum alloy as a material,
The present invention relates to a method for manufacturing a heat-treatable aluminum alloy member which is applied to manufacture a light alloy member having a thick and complicated shape having a specific shape portion including a protrusion, a recess and / or a through hole.

[Prior Art] As a heat treatment type aluminum alloy, for example, as described on page 514 of "Augmented Aerospace Engineering Handbook" issued by Maruzen Co., Ltd. on April 25, 1983, Al-Cu.
-Mg system (JIS 2000 system), Al-Mg-Si system (JIS 6000 system),
Al-Zn-Mg system (JIS 7000 system) and so on.

Conventionally, when manufacturing a heat-treatable aluminum alloy member having a complicated shape, a cast material made of the heat-treatable aluminum alloy is formed into a rectangular intermediate material by forging, and then, with respect to the rectangular intermediate material. In order to remove the residual stress after the solution heat treatment, followed by the solution heat treatment, in one direction with respect to the rectangular intermediate material,
For example, after performing cold compression in the thickness direction, aging treatment is performed, and further, by performing cutting processing on the intermediate material after the aging treatment, a specific shape portion such as a protrusion, a depression or a through hole is formed. The obtained aluminum alloy member has a complicated shape.

[Problems to be Solved by the Invention] However, in such a conventional method for manufacturing a heat-treatable aluminum alloy member, a rectangular intermediate material formed by forging is used for forming a recessed portion or a surplus portion that is later cut and removed. Since it is molded into a thick block shape that also includes the meat part and is subjected to solution treatment in this state, the thickness of the rectangular intermediate material during solution treatment is considerably large, and the effect of solution treatment Is not sufficient, and it is difficult to obtain high strength and high toughness. If the residual stress generated during solution treatment is not sufficiently removed from this alloy,
Not only distortion and cracks occur during cutting, but they also promote stress corrosion cracking when exposed to sea breeze and seawater.
Therefore, conventionally, residual stress is removed by subjecting a rectangular intermediate material to uniaxial cold compression after solution treatment. However, as described above, in such a method, for example, in the case of the 7075 alloy, it becomes impossible to secure sufficient strength and toughness at a wall thickness of about 100 mm.
Since it is difficult to remove residual stress sufficiently by compressing only uniaxially,
New methods need to be developed. As one of them, an intermediate material or a final finishing material having a specific shape portion such as a protruding portion, a depression portion or a through hole portion is subjected to solution treatment, immersed in liquid nitrogen at −196 ° C. instead of compression, and then continuously heated by steam. , "Uphill Quench Method" has been developed, which gives the opposite thermal cycle to solution cooling in the surface and inside of the plate.
However, in this method, not only the cost of the refrigerant is required, but also the equipment is extremely complicated, such as the arrangement of the steam nozzle in conformity with the shape, so that the control is not easy and the residual stress removing effect is not sufficient. Therefore, it has not reached widespread use.

Therefore, the inventors of the present application previously formed, in Japanese Patent Application No. 1-179724, an intermediate material having a specific shape portion such as a protrusion, a depression or a through hole from a cast material made of a heat treatment type aluminum alloy. After subjecting the intermediate material to the solution heat treatment, the intermediate material after the solution heat treatment is subjected to unidirectional cold compression with a compression strain of 1.5 to 5.0%, and a further compression strain of 1.5 to 5.0%. A method for manufacturing a heat-treatable aluminum alloy member is proposed, which comprises performing cold compression in at least two axial directions in which other cold compression is performed in another direction orthogonal to the one direction, and then performing an aging treatment. . According to this method, sufficient strength and toughness can be secured, and residual stress can be sufficiently removed. However, as a result of further studies, it was found that the above method may cause buckling or cracking at the time of compression when a thin portion partially exists.

The present invention has been made in view of such circumstances, and enhances the heat treatment effect by the solution heat treatment, and by making the effect of removing the residual stress generated by the solution heat treatment sufficient, the strength and An object of the present invention is to provide a method for manufacturing a heat-treatable aluminum alloy member that can improve toughness without causing cracking or buckling.

[Means for Solving the Problems] A method for manufacturing a heat-treatable aluminum alloy member having a thick and complex shape according to the present invention comprises performing plastic working and cutting on a cast material made of a heat-treatable aluminum alloy, Alternatively, by performing only plastic working, an intermediate material having a specific shape portion including a protrusion, a depression and / or a through hole is formed, and then the intermediate material is subjected to solution treatment, and then the solution treatment is performed. After inserting a metal dummy block having a deformation resistance of 70% or more and 200% or less of the deformation resistance of the processed intermediate material into the recesses and through holes, the compressive strain of the intermediate material is 1.5 to 5.0
% Cold compression in one direction and compression strain of 1.5-
It is characterized in that cold compression of 5.0% is performed in at least two axial directions in the other direction orthogonal to the one direction, and then an aging treatment is performed.

Hereinafter, the method for manufacturing the heat-treatable aluminum alloy member according to the present invention will be described in detail.

As the heat treatment type aluminum alloy applied in the present invention, as described above, for example, 2000 series represented by JIS2014, 2017, 2024, 6000 series represented by 6061, 7N01, 707.
There are 7000 series represented by 5, but it goes without saying that they are not limited to those established in JIS, Fe, S
An element such as n, V, Cr, or Mo is appropriately added, or an alloy obtained by increasing or decreasing the amount of these additional elements is used.

When manufacturing an aluminum member based on such a heat treatment type aluminum alloy based on the present invention,
First, by performing plastic working such as forging on a cast member made of the heat-treatable aluminum alloy, or by using such plastic working and cutting together, an intermediate as illustrated in FIG. 1 is obtained. Form the material 1.
This intermediate material 1 has four protruding parts 2a and one indented part.
2b and two through-holes 2c are provided as the specific shape portion 2 to form a thick and complicated shape. In addition, the specific shape portion here indicates a processed portion represented by the protruding portion, the depression portion, and the through hole portion, but is not necessarily limited to these and may include other shaped portions. . Further, it is not necessary for all of the protrusions, the recesses, and the through-holes to exist as such a specific shape portion, and only the recesses or the through-holes may be present.

Next, solution treatment is applied to the above-mentioned intermediate material 1.
This solution treatment is, for example, 490 ~ in 2024-T62 material.
Conditions for heating to 500 ° C and solution cooling followed by water cooling, 6061-T62
For the material, it is heated to 515 to 550 ° C for solution treatment and then water cooled, and for the 7075-T62 material, it is heated to 460 to 500 ° C for solution treatment and then water cooled.

Next, after inserting a metal dummy block having a deformation resistance of 70% or more and 200% or less of the deformation resistance into the recessed portion and the through-hole portion of the intermediate material 1 after the solution treatment, the residual by the solution treatment In order to remove the stress, cold compression is performed in at least two axial directions under predetermined conditions. This cold compression is
At least, the compression strain is performed in one direction cold compression is 1.5 to 5.0%, then the compression strain is performed in another direction orthogonal to the one direction cold compression is 1.5 to 5.0%,
As the biaxial directions in this case, for example, the Z direction and the Y direction as shown in FIG. 1 can be selected. In addition,
The order and direction of the cold compression are not particularly limited, and at least two axial directions that are easy to work can be selected from the three axes that are orthogonal to each other, and if necessary, the cold compression may be repeated three times or more.

In the present invention, the reason why the intermediate material 1 after solution treatment is cold-compressed in at least two axial directions is that the residual stress due to cold compression is caused only in one axial direction because the intermediate material 1 has a complicated shape. This is because there are areas where the removal effect cannot be expected. Reducing residual stress when cold-compressed in two axial directions Fig. 6, Fig. 7 and Fig. 8
It will be described with reference to the drawings.

FIG. 6 partially shows an infinite flat plate 20 having a plate thickness of 40 mm, in which the compression direction is Z, the plate thickness direction is Y, and the plate surface directions orthogonal to these two directions are X. .

Fig. 7 shows the flat plate 20 shown in Fig. 6 when heated to 470 ° C and then water-quenched in water at 20 ° C and then compressed in the Z direction (when external force is applied). The results of calculation of the change in internal stress with respect to the compressive strain by thermal stress analysis are shown below. The internal stress in the compression direction (Z direction) is σ _z , the internal stress in the plate thickness direction (Y direction) is σ _y , and the plate is The internal stress in the surface direction (X direction) is indicated by σ _x .

As is clear from FIG. 7, the internal stress σ in the Z direction
_z has a compressive strain of 1.5% or more, the same stress level on the surface and the center, and the internal stress σ _y and X in the Y direction.
The internal stress σ _{x in the} direction converges to 0 when the compressive strain is 1.5% or more. Since this analysis result is for the infinite flat plate 20 having a plate thickness of 40 mm, it is possible to obtain Y after the solution treatment.
The internal stress σ _{y in the} direction is 0, but in the case of a flat plate having an actual finite (predetermined) dimension, the internal stress σ _y also exists in the Y direction after the solution treatment. Therefore, the stress distribution in the plate thickness direction (Y direction) and the plate surface direction (X direction) orthogonal to the compression direction (Z direction) converges to 0 when the compressive strain is 1.5% or more. After cold compression from Z direction, internal stress (σ _z , σ _{y) is} obtained by performing cold compression in two or more axial directions, which is cold compression from the plate thickness direction (Y direction) or / and the plate surface direction (X direction). , σ _x ) has compressive strain
It will converge toward 0 at 1.5% or more. Conversely, it is difficult to bring all the internal stresses (σ _z , σ _y , σ _x ) close to zero by compressing only one axis.

FIG. 8 shows the residual stress distribution after releasing the cold compressive force in the Z direction from the state showing the change in internal stress due to compressive strain when cold compressing in the Z direction in FIG. . The state where the cold compressive force is released becomes the final residual stress state,
For example, when cold compression with a compression strain of 2.0% is performed, the residual stress becomes extremely small as shown in FIG.

As described above, in the present invention, the compressive strain during cold compression is defined to be 1.5% or more, which allows the internal stress to converge toward 0 as described above. But,
If the compressive strain is too large, the load on the intermediate material 1 becomes excessive, so it is specified to be 5.0% or less.

If the deformation resistance of the dummy block is less than 70% of the intermediate material after the solution heat treatment, the dummy block is easily deformed and is not used as a restraint body to prevent buckling or cracking. On the other hand, if it is more than 200%, the dummy block does not deform and the compressive deformation of the intermediate material does not proceed in the portion in contact with the dummy block, so that residual stress cannot be removed. A metal is desirable as a material that deforms similarly to the intermediate material. Therefore, the dummy block is made of metal and its deformation resistance is 70% or more of the deformation resistance of the intermediate material.
Specified below 0%. When inserting the dummy block, it is desirable to apply a lubricant such as MoS ₂ to prevent galling and to allow the deformation to proceed smoothly.
Also, the shape of the dummy block shall be the same size and shape as the indentation and through-hole of the intermediate material, considering the clearance of 0.3 mm or less. When the dummy block has a recessed portion and a through hole portion as the specific shape portion, they are inserted into both of them.

Then, the cold-pressed intermediate material 1 is subjected to an aging treatment, and then the surface of the intermediate material 1 is subjected to finishing processing such as cutting and polishing to a predetermined size if necessary. The heat-treatable aluminum alloy member having the specific shaped portion 2 such as the protruding portion 2a, the recessed portion 2b, and the through hole portion 2c is obtained. The aging treatment is, for example, for 2024 to T62 material, at 185 to 195 ° C. for about 9 hours, 606
1-T62 material at 155 ~ 165 ℃ for about 18 hours, 7075-T62
The material may be heated at 115 to 125 ° C. for about 24 hours or longer.

For reference, the “Uphill Quench method” described above
And degree of residual stress relief by compression method are shown in FIG. The difference in stress between the center of the wall thickness after quenching and the surface layer was 50 kg f / mm ² , while after aging it was 15 kg f / mm ² with uphill quenching and 5 kg with compression. Since it is f / mm ² , it can be seen that the compression method is superior as the residual stress removing method.

[Operation] In the present invention, before solution treatment,
By performing plastic working such as forging, or by using plastic working such as forging and cutting together, the cast material has a specific shape part including a protrusion, a recess and / or a through hole. Since the intermediate material that is similar to the product shape is formed and then the solution treatment is performed on the intermediate material, the thickness of the intermediate material becomes thin during the solution treatment, and the heat treatment effect by the solution treatment becomes sufficient. Further, after the solution treatment, cold compression is performed in at least two biaxial directions orthogonal to each other, so that cold compression is performed even in a region where residual stress removing effect by cold compression cannot be expected only in one axial direction. In addition, since the presence of the dummy block having the deformation resistance within the predetermined range allows the compressive stress to be effectively applied to the portion where the compressive stress is not originally applied, such as the indented portion, the residual stress generated by the solution treatment is applied. Can be removed extremely efficiently, and its removal effect becomes sufficient. Therefore, a heat-treatable aluminum alloy member having high strength and high toughness can be obtained. Further, at the time of compression, since the dummy block having the deformation resistance in the specific range is inserted into the recessed portion and the through hole portion of the intermediate material, buckling or cracking does not occur even in the thin portion.

[Example] A cast material made of JIS 7075, which is a heat-treatable aluminum alloy, was subjected to forging as a plastic working, so that three recesses 4a, 4b, 4c and 1 were formed as shown in FIG. Equipped with through-holes 4d at various locations as the specific shape part 4,
An intermediate material 3 having a length L ₂ = 680 mm, a width W ₂ = 660 mm, and a height H ₂ = 285 mm was prepared.

Then, for the intermediate material 3, as shown in FIG.
The solution treatment was performed under the conditions of heating to 468 ° C., holding for 6 hours, and then cooling with water.

Subsequently, a dummy block having a clearance of 0.3 mm or less and different in deformation resistance is inserted in a state where MoS ₂ is applied to the recess and the through hole, and the residual stress of the intermediate material 3 after the solution treatment is removed. Therefore, cold compression in the biaxial direction was performed on the solution-processed intermediate material. For comparison, cold compression was also performed on the sample without the dummy block inserted, and cold compression in the uniaxial direction was also tested. Various test conditions at this time are shown in Table 1. In Table 1, Test Nos. 1 to 3 are Examples within the scope of the present invention, and Test Nos. 4 to 9 are Comparative Examples deviating from the range. As to Test No. 4, as will be described later, a conventional method is used in which an intermediate material that does not form the specific shape portion is used and the specific shape portion is formed in the subsequent processing.

The cold compression in the biaxial direction at this time is the relationship between the compressive load and compressive strain of the 7075 material shown in FIG. 5, that is, the relationship expressed by the following equation (1) in the straight line part of FIG. Was performed as follows.

F ≒ [24.9 + 3.8δ] × S ………… (1) [however, F is press load (kg f), δ is compressive strain (%), S is press cross-sectional area (mm ² ), unit of constant Is kg f /
mm ² . That is, for the intermediate material 3 after the solution treatment, first, cold compression in the Z direction in FIG. 2 is performed with a compression load of about 67 tons except for some samples to achieve a compression of about 2.5%. Distortion is applied, and then Y in FIG.
Except for some samples, cold compression in the Z direction was performed under the same compressive load of about 67 tons to give a compressive strain of about 2.5%. Compressed. The test number 9 was uniaxially compressed only in the Z direction.

Then, as shown in FIG. 3, the intermediate material 3 after cold compression is heated at 108 ° C. for 7 hours and at 165 ° C. for 7 hours.
After performing a two-step aging treatment for a time, a finishing process (cutting process) is performed to obtain a heat-treatable aluminum alloy member having a specific shape portion 4 including the recessed portions 4a, 4b, 4c and the through hole portion 4d. .

The member of test number 4 was formed as follows.

That is, first, a casting material made of JIS 7075, which is a heat-treatable aluminum alloy as in the above-mentioned embodiment, is forged, and as shown in FIG. 4, a length L ₄ = 680 mm,
A rectangular block-shaped intermediate material 10 having a width W ₄ = 660 mm and a height H ₄ = 310 mm was prepared.

Subsequently, the block-shaped intermediate material 10 was subjected to a solution treatment under the conditions of heating to 468 ° C., holding it for 6 hours, and then cooling with water, as shown in FIG.

Next, the block-shaped intermediate rough material 10 after the solution heat treatment is subjected to cold compression in the Z direction only in FIG. 4 by a compression load of about 67 tons to give a compression strain of about 2.5%. It was to so.

Then, similarly to the above-described embodiment, as shown in FIG. 3, a two-step aging treatment of 108 ° C. × 7 hours and 165 ° C. × 7 hours is performed, and then the block-shaped intermediate material 10 is subjected to cutting work. As a result, the recesses (4a, 4b, 4c) having the same shape and size as those of the embodiment shown in FIG.
A heat-treatable aluminum alloy member having the specific shaped portion 4 including the d) and the protrusion (4e) was obtained.

The surface residual stress (center of the back surface, protruding portion) of each aluminum alloy final finishing member thus obtained
4e height / width center), tensile properties, and fracture toughness were evaluated.
The results are shown in Table 1. The residual stress was measured by the drilling method (ASTM E837) at the center position on the back surface side in FIG. 2 or FIG. 4 of the surface layer and the height and width center of the protrusion 4e. It was measured at the height center and the wall thickness center of the protruding portion sandwiched between 4b.

As is clear from the results shown in Table 1, in the case of Test Nos. 1 to 3 of the examples of the present invention, buckling and cracking did not occur and residual stress was almost removed after the two-step aging treatment. Also, good values were obtained for the yield strength (YS), tensile strength (TS), and fracture toughness (K _IC ) and it was confirmed that the effects of the present invention were sufficiently obtained.

On the other hand, test No. 1 quenched in the shape of a rectangular parallelepiped is inferior in strength and toughness, and when the dummy block is not inserted as in Test Nos. 5 and 7, or the deformation resistance is too low even when inserted, It was confirmed that buckling and cracking occurred in the thin portion. Also, if the compressive strain amount is small as in Test Nos. 6 and 8 or if the deformation resistance of the dummy block is too high, a sufficient residual stress relief effect cannot be obtained, and as in Test No. 6, uniaxial (Z direction) It was confirmed that the residual stress cannot be effectively removed by only compression.

[Effects of the Invention] As described above, according to the method for manufacturing a heat-treatable aluminum alloy member of the present invention, the wall thickness at the time of solution treatment can be reduced, so that the heat treatment effect by solution treatment can be achieved. Can be sufficient. Further, since residual stress can be sufficiently removed without causing buckling or cracking during compression, it is possible to obtain a heat treatment type aluminum alloy member having excellent strength and toughness. Further, since the residual stress of the aluminum alloy member can be reduced in this way, the stress corrosion cracking resistance can be improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of an intermediate material before heat treatment used in the method for producing a heat-treatable aluminum alloy member according to the present invention, and FIG. 2 shows a shape of the intermediate material before heat treatment used in an embodiment of the present invention. FIG. 3 is a perspective view showing the heat treatment conditions applied in Examples and Comparative Examples of the present invention, and FIG.
The figure is a perspective view showing the shape of the intermediate material before heat treatment used in the comparative example, FIG. 5 is a graph illustrating the result of examining the relationship between compressive load and compressive strain in 7075 material, and FIG. 6 is the biaxial direction. 7 is a perspective view showing an infinite flat plate for explaining the cold compression of FIG.
FIG. 8 is a graph illustrating the relationship between stress and compressive strain when cold-compressed in the biaxial direction, FIG. 8 is a graph illustrating residual stress distribution after releasing cold-compressive stress, and FIG. 9 is “ It is a figure which compares and demonstrates the degree of residual stress relief of an uphill quench method "and a compression method. 1,3 …… Intermediate material, 2,4 …… Specific shape part, 2a, 4e …… Projection part, 2b, 4a, 4c …… Indentation part, 2c, 4d …… Through hole part.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yoshimichi Hino, Marunouchi 1-2-2, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Tetsuo Sakiyama 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Main Steel Pipe Co., Ltd. (72) Inventor Katsuhiko Hirokami 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Japan Steel Pipe Co., Ltd. (72) Inventor Souji Shimizu 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa (56) References JP-A-63-153252 (JP, A) JP-A 1-116054 (JP, A)

Claims (1)

[Claims] 1. A method for producing a heat-treatable aluminum alloy member having a thick and complex shape having a specific shape portion including a protrusion, a recess and / or a through hole, which is a cast material made of a heat-treatable aluminum alloy. On the other hand, by performing plastic working and cutting, or by performing only plastic working, an intermediate material having a specific shape portion including a protrusion, a depression and / or a through hole is formed, and then the intermediate material is formed. After subjecting the solution treatment to the solution treatment, and then inserting a metal dummy block having a deformation resistance of 70% or more and 200% or less of the deformation resistance of the intermediate material after the solution treatment into the recessed portion and the through hole portion, Cold compression is performed in one direction with a compression strain of 1.5 to 5.0% with respect to the intermediate material, and cold compression with a compression strain of 1.5 to 5.0% is performed in another direction orthogonal to the one direction. Both performs compression between two axial cooling method for heat-treatable aluminum alloy of thick and complex shapes, characterized in that thereafter the aging treatment.