JPS5827336B2 - High toughness, high strength Al alloy casting products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an A1 alloy cast product, and particularly to an A1 alloy cast product that exhibits excellent toughness and strength without being subjected to heat treatment.

A1 alloy cast products are attracting attention as a product that meets the demand for weight reduction, and in particular, the demand for A1 alloy cast wheels, guardrail poles, etc. is showing a tendency to increase more and more.

By the way, this type of A1 alloy casting product is mainly JI5A.
It is manufactured from C4C alloy (AI-7%Si: 0.3%Mg), but since cast products like the ones mentioned above are important safety parts related to human life, they are not only strong but also have toughness, elongation, etc. A high level of performance is required.

For this reason, conventionally, in order to further increase the strength and toughness of the above alloy, T6 treatment [usually (520-540°C) x (5-1
However, not only is the performance still insufficient, but also the operational and economic burden required for heat treatment is high. There is also the problem of being strengthened (7).

Under these circumstances, in order to obtain an AI cast alloy that exhibits excellent strength and toughness without heat treatment, various studies have been conducted on the types and amounts of alloy components.

Among these types of non-heat-treated alloys, Al-Mg cast alloys are currently considered to be superior, and for example, JISA
C7A alloy (Al-3, 5-5.5% Mg) is known, but although this alloy has excellent tensile strength and elongation, it has poor yield strength and is not suitable for guardrail poles or AI cast wheels. It is still unsuitable as an alloy.

The present inventors have also conducted research in this field, and in particular, have conducted intensive research on how the Mg content and the types and addition rates of other trace elements affect the physical properties of AlMg-based cast alloys. I've made progress.

As a result, if the type and content of the added alloying elements are specified as shown below, the tensile strength, elongation,
After learning that it was possible to obtain an A1 alloy cast product that satisfies both toughness and yield strength, the present invention was finally completed.

That is, the alloy composition of the A1 alloy cast product according to the present invention is as follows:
Mg: 2.5 to 80% (weight% 2 or less is the same), Ti
: 0.03 to 0.2%, B: 0.001 to 0.02, and further contains Zr: 0.01 to 1.5% and/or Cu 0.15 to 0.7%, the balance Consists of AI and inevitable impurities, or in addition to these, Cr: 0.05 to o,
The gist lies in containing one or both of s% and/or Zn: 0.05 to 1.0%, and Si: 0.05 to 0.5%.

The effects of each additional alloying element and the basis for limiting the content will be explained below based on drawings showing experimental results.

(Mg) FIG. 1 is a graph showing the relationship between the amount of added calories of Mg and the physical properties using Al-0.3%Mn-0.1%Fe as the basic component.

However, the conditions for preparing the sample were: mold temperature: 180±10°C, and casting temperature: T-8+100°C.

In addition, the black circles in FIG. 1 indicate the physical properties of non-heat treated materials, and the x marks indicate the physical properties after heat treatment (T4: 430° C. x 20 hours).

As is clear from the results in Figure 1, looking at the influence of the Mg content in non-heat treated materials, the tensile strength (TS) is
It improves as the amount increases up to a maximum of 8φ, but reaches a maximum value at 8φ and decreases beyond that.

In addition, the yield strength (ys) increases as the Mg content increases, and the elongation rate (Ei) decreases rapidly after 5%, and the impact strength I
c) decreases with increasing Mg content.

Judging from these physical properties comprehensively, the Mg content is 2.5 to 8.
The rice cake range is most preferred.

However, if it is less than 2.5%, the tensile strength and yield strength will be less than 20 kg/m2 and less than 10 kg/Km'', respectively, and the strength will not be satisfied, and if it exceeds 8%, the elongation rate will be less than 20 modulus, and the impact strength will be less than 20%. The toughness becomes less than 1 kg·m/-, resulting in poor toughness.

Also, as is clear from comparing the trends of the black circles and the x marks, Mg
In the range of 2.5 to 8 modulus, there is almost no difference in physical property values depending on whether or not heat treatment is performed, and the elongation and impact strength of the non-heat treated material are rather high.

That is, when the Mg content is in the range of 25 to 8, no heat treatment is necessary at all, and rather the strength as it is without heat treatment exhibits excellent physical properties.

Figure 2 shows the Al-5%MgO, 3%Mn alloy (non-heat treated: inventive material) and AC4C T6 heat-treated material (heat treatment conditions, component composition, and physical properties are as follows: conventional material).
It is a graph showing the results of measuring fatigue strength using a shank type bending fatigue tester (the test piece is shown in FIG. 3).

In Fig. 2, the white circles indicate the conventional material, and the black circles indicate the present invention material.

(AC4C, T6 heat treated material) Heat treatment conditions: 535°C x 5 hours + 140°C x 4.5
Time component composition: Al-6,9Si-0,12Fe-0,3
Mg-0,13Ti Tensile strength: 24.5-25.1 kg/M2 crab resistance 13.5-14.2 kg/application 2 Elongation rate: 18. O~24. Hardness: 62.5 to 69.1HB Impact strength: 1.05 to 1.24 ky・m/fflAs is clear from these results, the material of the present invention is comparable to conventional heat-treated materials, and even better than this. It has a fatigue strength exceeding .

Next, in the present invention, it is necessary to add a predetermined amount of one or both of Zr and Cu.

[Zr amount in Figure 4 is Al-5%Mg-0,3%Mn-0,07
It is a graph showing the influence of the amount of Zr on each physical property value using %T i -0,003%B as a basic component.

Furthermore, Table 1 collectively shows the influence of Zr and other trace amounts of added elements on the fatigue strength (number of repeated bending) for the above basic components.

From these results, Zr has the effect of improving tensile strength and yield strength without significantly reducing elongation (the fourth
), and as is clear from Table 1, the fatigue strength is significantly improved.

In order to exhibit these effects significantly, it is necessary to contain Zr at least 0.01φ or more, but on the other hand, if the content is too high, the elongation decreases as seen in Figure 4, so it is necessary to have a coefficient of 1°5 or less. should be kept to a minimum.

By the way, it is known to add Zr to Al-Mg-based wrought alloys.

However, the main purpose of this is to increase the recrystallization temperature by adding Zr and suppress recrystallization during processing, and as in the present invention, zero Zr is added to the A1 alloy for casting to increase strength and fatigue strength. There is no precedent.

(Cu) FIG. 5 is a graph showing the influence of the amount of Cu on each physical property value using Al-5%Mg as the basic component.

As is clear from the results in FIG. 5, as the amount of Cu increases, the tensile strength and yield strength improve, but the elongation decreases.

Further, as shown in Table 1, the fatigue strength can be considerably increased by adding Cu.

In order to significantly exhibit these effects of improving tensile strength, elongation, and fatigue strength, it is necessary to contain at least 0.05% Cu.

However, if the amount of Cu is too large, the elongation rate will decrease to less than 20 yen, and as will be described later, the corrosion resistance will decrease, which is not suitable for the purpose of the present invention, so it must be suppressed to 0.7% or less.

(Ti) and CB) Ti has the effect of refining the crystal structure of the alloy and improving its physical properties, and the range where it can most effectively exhibit its effect is 0.03
~0.2φ.

Further, the effect of Ti is enhanced by the combined use of 0.001 to 0.02% of B.

Although the purpose of the present invention is achieved to some extent by specifying the content of each alloying element as described above, the elongation rate can be particularly reduced by further containing an appropriate amount of Cr and/or Zn as shown below. It is possible to increase the tensile strength without reducing the amount of Si, and by incorporating an appropriate amount of Si, the fatigue strength can be significantly improved.

[Cr amount Figure 6 shows the same <Al-5%Mg as the basic component, Cr
This is a graph showing the influence of the amount of Cr on each physical property value.
As the amount increases, the tensile strength and yield strength improve and the elongation decreases.

In order to ensure sufficient tensile strength and yield strength and an elongation rate of 20 or more, the Cr content should be set in the range of 0.05 to 0.8%.

(Zr+) FIG. 7 is a graph showing the influence of each physical property value on the amount of Zn.

Here, the basic component was AI-03%Mn, and the influence of the Zn content was also observed when the Mg content was varied.

As is clear from the results in Figure 7, the influence of Zn content on each physical property value is almost the same even when the Mg content is changed, but in general, Zn increases tensile strength without significantly reducing elongation. It has the effect of increasing the hardness, and in order to exhibit this effect significantly, it should be added in an amount of at least 0.05% or more.

However, even with a superaddition of 1.0%, no further effect was observed, and on the contrary, the elongation and impact strength were significantly lowered, so 1.0φ was set as the upper limit.

Figure 8 shows the same <Al-5%Mg as the basic component, and Si
This is a graph showing the influence of the amount of Si on each physical property value.
As the amount increases, the yield strength and elongation decrease.

However, as shown in Table 1, Si has the effect of significantly increasing fatigue strength, and in order to effectively exhibit this effect, it is necessary to
It is necessary to add 0.5% or more.

However, if the amount of Si exceeds 0.5 yen, the elongation rate and impact value particularly decrease, so it should be kept below this amount.

The essential constituent elements in the present invention are as described above, and the remainder consists of AI and unavoidable impurities, but elements that are negative elements will also be briefly explained.

[Amount of Fe Figure 9 is a graph showing the influence of the amount of Fe on each physical property value using Al-5%Mg as the basic component.

This graph shows that although Fe has the effect of slightly increasing the tensile strength, the effect is extremely small, and rather has the opposite effect of decreasing the elongation and impact value.

Therefore, it is desirable to suppress the amount of Fe to 0.6φ or less.

(Mn) Mn has the effect of preventing the above-mentioned failure of Fe, which is generally mixed into Al-Mg alloys, and increasing the yield strength.

Therefore, when Fe is contained in the alloy, it is desirable to actively add Fe, but if it is too large, the elongation and impact strength will decrease, so it should be kept at 0.6% or less.

(Ni amount 1 Figure 10 shows the same <Al-5%Mg as the basic component, N
3 is a graph showing the influence of the amount of i on each physical property value.

As is clear from this graph, although Ni has the effect of slightly increasing tensile strength and yield strength, it significantly lowers elongation and impact strength, and furthermore, as shown in Table 1, significantly lowers fatigue strength.

Therefore, the amount of Ni is such that these obstacles are virtually no problem.
．． It is best to keep it below 5%.

(Ag) In Figure 11, the same <Al-5φMg is used as the basic component, and A
This is a graph showing the relationship between the amount of g and each physical property value, but Ag does not have a significant positive effect, and only decreases the elongation rate and impact strength.

Therefore, Ag should be suppressed to 0.5% or less so that these negative effects do not become a substantial problem.

The A1 alloy casting product of the present invention consists of the above alloy components,
By specifying the type and amount of the metal element with zero thrust for AI as described above, the conventional A
It was possible to ensure high toughness, high strength, and high yield strength comparable to or exceeding that of heat-treated alloys.

In addition, A1 alloy is often required to have excellent corrosion resistance depending on its use, but the A1 alloy casting product of the present invention has excellent corrosion resistance.
As shown in the table, it is extremely excellent in both physical properties and corrosion resistance.

[Brief explanation of the drawing]

Figures 1 and 4 to 11 are graphs showing the relationship between the amount of added alloying elements and each physical property value, Figure 2 is a graph showing the relationship between bending stress and number of repeated bends, and Figure 3 is for measuring the number of repeated bends. It is a figure showing a test piece.

Claims (1)

[Claims] I Mg: 2.5 to 8% (weight: the same applies hereinafter), Ti
: 0.03~0.2%, B: 0.001~0.02%, further Zr: 0°01~1.5% and Cu:
A high-toughness, high-strength A1 alloy casting product characterized by containing one or two types of 0.15 to 0.7φ, with the remainder consisting of AI and inevitable impurities. 2 Mg: 2.5 to 8 悌 (parts by weight: the same below), Ti
: 0.03-0.2%, B: O, OO 1-0.02%, and Zr: 0.01-1.5% and Cu: 0
．． Cr: 0.
A high-toughness, high-strength A1 alloy casting product characterized by containing one or two of 0.05-0.8% and Zn: 0.05-1.0%, with the remainder consisting of AI and inevitable impurities. 3Mg: 2.5-8 (same weight below 2), Ti: 0
．． 03-0.2%, B: 0.001-0.02% and S
i: 0.05 to 0.5%, further Zr: 0.01
~1.5 and Cu: A high toughness, high strength A1 alloy casting product characterized by containing one or two of 0.15 to 0.7%, and the remainder consisting of AI and inevitable impurities. 4Mg: 2.5 to 8 units (weight% 2 or less is the same), T1: 0
．． 03-0.2%, B: 0.001-0.02% and S
i: Contains 0.05 to 0.5%, and Zr: 0.0
1-1.5% and Cu: 0.15-0.7% 1
In addition to containing one or two types of Cr: 0.05 to 0.8% and Zn: 0.05 to 1.0%,
A high-toughness, high-strength A1 alloy casting product characterized in that the remainder consists of AI and unavoidable impurities.