JPS63230843A - Structural al-mg-si-cu alloy excellent in toughness and strength - Google Patents

Abstract

PURPOSE:To develop a structural Al alloy excellent in toughness as well as in strength, by adding specific amounts of Mg, Si, Cu, Mn, and Zr and/or V to Al. CONSTITUTION:An Al alloy having a composition in which 0.60-0.90%, by weight, Mg, 0.50-0.80% Si, 0.40-0.80% Cu, and 0.20-0.60% Mn are incorporated to Al in a range satisfying a condition of 5.2XSi%<=3XMg%+1.73XMn%+0.5% and further 0.05-0.25% Zr and/or 0.05-0.20% V is incorporated in an amount satisfying 0.05%<=Zr%+V%<=0.20% is manufactured. In this way, the structural Al alloy having strength and toughness required of structural materials, machine parts, etc., can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION ``Object of the Invention'' The present invention provides a structural A7 with excellent toughness and strength! -Mg-
The present invention relates to a 5t-Co alloy and aims to provide an aluminum alloy with excellent toughness and strength, which are important for structures.

(Industrial Application Fields) Alloys used for equipment components such as automobiles, railway vehicles, motorcycles, bicycles, and aircraft, and other mechanical parts.

(Conventional technology) Conventionally, structural aluminum alloys have a yield strength of 4
Al2-Cu alloy and Al2-Zn-Mg-Cu alloy with yield strength of 30 to 35 kg
/Al-Zn-Mg alloy with dragon 2, yield strength 25~
An AN-Mg-3t alloy having a yield strength of 35 kg/Tsuru2 and an A1-Mg alloy having a yield strength of 15 to 20 kg/m'' are known.

(Problems to be Solved by the Invention) Al-Cu alloys and Ant-Zn-Mg-Cu alloys have the highest strength among aluminum alloys and are mainly used in aircraft, but they have poor corrosion resistance and extrusion resistance. Poor workability.

The 8l-Zn-Mg alloy has excellent extrusion workability and weldability, and is also better in corrosion resistance than the Al-Mg-based alloy and the Al-Zn-Mg-Cu-based alloy, so it is mainly used in railway vehicles. Although it is used, its strength is insufficient.

Although Al-Mg alloys have excellent weldability and corrosion resistance, their strength is significantly inferior to other alloy systems, and their extrusion workability is also inferior.

On the other hand, the β-Mg-5i alloy has good corrosion resistance and excellent extrusion processability, especially with a yield strength of 25 kg.
/mm'' grade 6061 alloy is widely used as structural members, but its strength is insufficient, and its strength is 30 to 3
6066 alloy increased to 5 kg/1111”, 6
070 alloy, 6082 alloy, etc. have poor toughness and lack credibility as structural materials, so their uses are limited.

In other words, in recent years there has been an increase in the demand for lighter weight machine parts and structures, and the use of such aluminum alloys has also increased.
There is a strong demand for products with high toughness and yield strength of 0 kg/Im2 or more, especially 35 kg/f12 or more.
Aluminum alloy materials that can meet such demands have not yet been put into practical use.

"Structure of the invention" (Means for solving the problem) Mg: 0.60-0.9wt%, St: 0.5
o~o, awt%, Cu: 0.40~0.8wt
%, Mn: 0.20 No, within the range of 6wt%, and 5.2×Si%≦3×Mg%+1.73×Mn
%+0.5% of Mg.

Contains Si, Mn and Cu, and further contains Zr: 0.
05-0.25%, V: within the range of 0.05-0.20%, and 0.05%≦Zr%+ν%≦0.20%
A structural material with excellent toughness and strength, characterized by containing one or both of Zr and V in an amount that satisfies the following conditions, and the remainder consisting of Al and impurities.
g-St-Cu alloy.

(Function) Mg, Si, and Cu are at least the lower limit and the amount ratio is 5, where excess St does not occur. 2×Si%≦3×Mg%+1.
By containing 73×Mn%+0.5%, MgzSi fine particles are precipitated in a uniformly dispersed state by aging after solution treatment, and large strength is imparted by precipitation hardening. Also, by keeping these below the upper limit, deterioration of toughness is avoided.

By containing Mn above the lower limit, A I MnSi phase particles are precipitated by homogenization treatment to improve toughness. Furthermore, by keeping Mn below the upper limit, an increase in quenching sensitivity and a decrease in toughness are avoided.

By containing one or both of Zr5V in an amount above the lower limit, the unrecrystallized structure due to hot working is stabilized and toughness is improved. On the other hand, a decrease in toughness can be avoided by keeping the amount below the upper limit (0.20% is the upper limit when both are contained).

To further explain these technical relationships in terms of % (hereinafter simply referred to as %), Mg forms a st phase with St, and precipitates as G, P, zones and intermediate phases by aging after solution treatment. Improve strength.

If this Mg is less than 0.60%, sufficient strength cannot be obtained, while if it exceeds 0.9%, hot workability is reduced, so the range is set from 0.60 to 0.9%. Si is Mg and M
gzSi phase is formed and the strength is improved as mentioned above, but if it is less than 0.50%, sufficient strength cannot be obtained;
Over 8% or even within 0.8%, 5.2×Si%≦3
If the relationship: 'xMg%+1.73xMn%+0.5% is not satisfied, the toughness will deteriorate, so the content is set at 0.50 to 0.8%. Cu precipitates the MgzSi phase finely and uniformly,
Improve strength and toughness. If it is less than 0.40%, the effect is not sufficient, while if it exceeds 0.8%, hot workability deteriorates and corrosion resistance decreases. Therefore, it is set at 0.40 to 0.8%.

Mn mainly precipitates as an A I MnSi phase during homogenization treatment and improves toughness, and if it is less than 0.20%, this effect is not sufficient, while if it exceeds 0.6%, quenching sensitivity increases. , reducing strength and toughness.

In addition, the amount of crystallized particles generated during casting increases, resulting in a decrease in toughness, so the content should be within the range of 0.20 to 0.6%.

Zr and V are mainly used in lrA l during the homogenization process.
3 and VAβ1°, which stabilizes the hot-worked structure and is effective in improving toughness and strength.

In this case, if Zr is used alone, its effect will not be sufficient if it is less than 0.05%, while if it exceeds 0.25%, a coarse ZrAl 2 phase will be formed during casting and the toughness will deteriorate. Therefore, it is necessary to set it in the range of 0.05 to 0.25%.

Further, when V alone is used in an amount of less than 0.05%, the above-mentioned effects are insufficient, and on the other hand, if it exceeds 0.20%, VAN becomes coarse during casting. Since phases are formed and the toughness is deteriorated, the content is set in the range of 0.05 to 0.20%.

Further, even when Zr and V are added at the same time, the effect is not sufficient if the sum of the amounts of both is less than 0.05%. On the other hand, if it exceeds 0.20%, coarse ZrAl!
:l and VANI. Phases are formed and deteriorate toughness. Therefore, the range is 0.05≦Zr%+V%≦0.20%.

In addition, in addition to the above-mentioned components, the product according to the present invention contains one or both of TI%B, which is generally added for prevention of casting cracks and grain refinement, within the range normally used. It's okay.

The effect is obtained in the same way as when Ti is added generally, but if Ti exceeds 0.15% or B is 0.01%
If it exceeds %, Ti Aj! 3. Since coarse particles such as TiBz and AJB2 are generated and the toughness is reduced, the upper limit of Ti is 0.15% and the upper limit of B is 0.01%.

In addition, as impurities, Fe50.3%, Zn≦0.3%
If it is within this range, it is permissible because it does not deteriorate the characteristics of the present invention. However, since Cr significantly increases quenching sensitivity and reduces strength and toughness, it is desirable that Cr<0.05%.

(Example) The alloy according to the present invention can be suitably produced by conventional methods. That is, it is melted in the same way as a normal aluminum alloy, and the above-mentioned grain refiners such as Ti and B are melted in a melting furnace.
Alternatively, it is continuously added to the molten metal transfer trough to the casting machine, then filtered to remove nonmetallic inclusions such as oxides in the molten metal, and finally made into an ingot by a semi-continuous casting method. Next, the ingot is homogenized, and the purpose of this homogenization treatment is to homogenize Mg, SL, Cu, etc. that were segregated during casting,
Supersaturated solid solution of Mn5V% Zr, etc.
The purpose is to precipitate I MnSi, VAl, and 01ZrAJs in a uniformly distributed state.

For this alloy, it is preferable to adopt conditions in which the alloy is heated at a temperature increase rate of 200° C./Hr or less and maintained at 540 to 570° C. for 2 to 24 hours. Next, one or both of hot working and cold working is performed, and when the hot working is extrusion working, it is desirable to perform it at a temperature of 520 to 550°C. Solution treatment after processing is at 540-570℃, 0.5-
2 hours is appropriate. Further, it is preferable to quench at a cooling rate of 150°C/min or more, and finally to a temperature of 150°C to 19°C.
The desired product can be obtained by artificial aging at 0° C. for 2 to 24 hours.

A specific manufacturing example of the product according to the present invention will be described below.

Examples 1 to 1 of the present invention having component compositions as shown in Table 1 below
6 and Comparative Examples A-J were melted, and 0.01% Ti was added to Al-5% Ti-1% B.
It was added to the alloy and semi-continuously cast as an ingot of 203 waφ.

Table 1 Each obtained ingot was heated at a temperature increase rate of 100°C/hr, held at 550°C for 6 hours, and then cooled at 300"C/hr. Then, it was extruded at 540°C to a thickness of 10 mm. Hot extrusion processing is performed on the bar, and the extruded bar is heated at 550℃ for lh.
R solution treatment and water quenching.

Finally, artificial aging was performed at 165°C for 8 hours.

Regarding such extruded materials, the strength was measured by a tensile test and the toughness was measured by a tear test. Regarding the measurement of toughness by tearing test, as shown in Figure 1, a 45° angle cutout was made in the center of one side of test piece 1, which was 40mm wide, 60mm long, and 5mm thick. 2 with a low depth, and application points 3 that apply a tensile force at positions equally spaced from the notch 2 on a straight line parallel to the side edge passing through the bottom of the ■-shaped notch 2.
．． 3 were prepared symmetrically. In addition, the method for measuring and evaluating toughness using such a test piece 1 is to calculate notch toughness σwax and tear resistance t1. from the load-displacement curve shown in FIG. P, E, were found.

tymax=Pmax/S……111
, P, E = A/S ...... ■
However, for vines, Pmax: Maximum load in Figure 2.

S: Behavioral cross-sectional area of the test piece.

A: The shaded area in Figure 2 area.

Furthermore, the metal & II texture was observed using an optical microscope.

The evaluation criteria for strength and toughness were set as follows.

0.2% yield strength ≧30kg/Ryu2 σ1IIaX ≧13.5 kg/va”U,
P, E ≧ 20 kg/
A summary of the measurement results obtained is shown in Table 2 below.

In addition, the conventional ^J-Mg-S mentioned above for reference in the performance
The test results for i-series alloys are shown in Table 3 below.

According to the measurement results in Table 3, that is, Table 2 above, the aluminum alloy having the alloy composition within the range of the present invention has a 0.2% yield strength compared to that of the comparative example or reference example (Table 3). In addition, σll1aX is even better, and U, P.

It was confirmed that all of them had an excellent toughness and strength of 20 kgw/as" or more.

"Effects of the Invention" According to the present invention as explained above, it is possible to accurately obtain a product with an excellent and desirable balance of strength and toughness required for structural materials, machine parts, etc., for this type of structural aluminum alloy. This invention is industrially highly effective.

[Brief explanation of the drawing]

The drawings show the technical contents of the present invention, and Fig. 1 is a plan view and side view showing the configuration of the test piece, and Fig. 2 is a plan view and a side view showing the configuration of the test piece.
The figure is a graphical explanatory diagram of a load-displacement curve in a tear test. In these drawings, 1 indicates a test piece, 2 indicates a square notch, and 3 indicates a tensile force application point. Patent applicant Nippon Light Metal Co., Ltd. Inventor Katsuki Shinohara
/ Hideni Kai Kushi

Claims (1)

[Claims] Mg: 0.60-0.9 wt%, Si: 0.50-0.
8wt%, Cu: 0.40-0.8wt%, Mn: 0.
Within the range of 20 to 0.6 wt%, and 5.2 x Si%
Contains Mg, Si, Mn, and Cu in an amount that satisfies the condition of ≦3×Mg% + 1.73×Mn% + 0.5%, and further contains Zr: 0.05 to 0.25 wt%, V: 0.05 ~0.
Within the range of 20wt% and 0.05%≦Zr%+V
Structural Al-Mg with excellent toughness and strength, characterized by containing one or both of Zr and V in an amount satisfying the condition of %≦0.20%, with the remainder consisting of Al and impurities. -Si-Cu alloy.