JPS6289838A - High strength aluminum alloy excellent in rolling workability - Google Patents

Abstract

PURPOSE:To obtain a high strength Al alloy excellent in hot rolling workability in particular and used as rolled plate for various purposes such as structural use, machine parts, etc., by providing a composition containing Zn, Mg, one or more among rare earth elements and, if necessary, one or more elements among Mn, Cr and Zr each in a prescribed percentage. CONSTITUTION:The high strength Al alloy excellent in rolling workability has a composition consisting of, by weight, 4-12% Zn 0.3-2.5% Mg, 0.5-10% of one or more kinds among rare earth elements, and the balance Al with inevitable impurities and further containing, if necessary, the following optional additive components: one or more kinds among 0.1-0.8% Mn, 0.05-0.30% Cr and 0.05-0.25% Zr. This Al alloy combines high strength practically comparable to that of conventional rollable high-strength Al alloy with characteristics such as excellent rolling workability, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a high-strength aluminum alloy particularly excellent in hot rolling workability, which is used as a rolled plate for various purposes such as structural and mechanical parts.

In this specification, "%" is used to indicate the maximum percentage.

Conventional Technology and Problems Conventionally, A707, a Ω-Zn-MtJ system, has been used as a typical aluminum alloy that has high strength and can be rolled.
5 alloy is well known.

However, the 7075 alloy is still not easy to roll, and furthermore, it contains a considerable amount of CU in the range of 1.2 to 2.0%, making it impossible to weld.
It was.

In addition, recently there has been an increasingly strong demand for high-strength, thin-walled rolled materials, and in response to these demands, the amount of ln added has been increased in order to further improve strength without reducing rollability. There is a tendency to However, when the amount of Zn added increases, this (accompanyingly, the stress corrosion cracking resistance of the alloy decreases,
This results in something that cannot be put to practical use. On the other hand, there is a tendency to increase the amount of MO added in order to improve strength while maintaining relatively good stress corrosion cracking resistance, but in this case, there is a problem that the rollability decreases and the productivity of the rolled material decreases. points are occurring.

In view of the problems of the prior art as described above, this invention improves the stress corrosion cracking resistance of the Ω-high n-low MrJ alloy, which is predicted to be an alloy with excellent rolling workability. The purpose of this invention is to provide a high-strength aluminum alloy for rolling that has excellent rolling properties, weldability, and stress corrosion cracking resistance.

Means for Solving the Problems The present invention, as a result of various experiments and research for the above-mentioned purpose, aims to improve the required strength by increasing the amount of Zn without increasing the amounts of Mgl and Qu. Low Mg
Based on the alloy, YlLa SCe, Pr
By adding rare earth elements such as , Nd, Sm, etc., we discovered that scales have remarkable stress corrosion cracking resistance, and as a result, we were able to commercialize a high-strength aluminum alloy with good rollability. be.

That is, in this invention, Zn: 4 to 12%, Mg: 0.3
~2.5%, or further contains Cu: 0.05~0.7%, and contains one or more rare earth elements in a total of 0.5~10%, and further as necessary. The gist of the present invention is to provide a high-strength aluminum alloy for rolling which has excellent rolling workability and contains the following optional additive components and the balance is aluminum and unavoidable impurities.

In the concrete implementation of the alloy of the present invention, in addition to the above-mentioned essential components, other optional additive components include Mn: 0.1-0.8%, Cr: 0.05-0.3%.
0% and Zr: 0.05 to 0.25%, one or more of them may be contained as necessary. Therefore, alloys containing these optional components are also compatible with the intended purpose of the present invention and are included within its scope.

The reasons for limiting each of the alloy components and their proportions are as follows.

As is known, both Zn and MO mainly contribute to improving the strength of the alloy, and when Zn is less than 4% and M
If g is less than 0.3%, sufficient strength cannot be obtained. On the other hand, even if ln is contained in an amount exceeding 12%, no proportional strength improvement effect can be expected and it is essentially meaningless. Mg is 2.5
If the content exceeds 5%, the strength will improve, but the rolling properties will decrease, making it impossible to meet the intended purpose of the present invention.

As is known, CLI contributes to improving strength, but if the content is less than 0.05%, the effect is not sufficient, and if it exceeds 0.7%, it deteriorates weldability, corrosion resistance, and hardenability. decreases.

The rare earth element added to the alloy is not particularly limited, but specifically, for example, Y, La, Ce 1P
Preferred examples include r 2 , Nd 2 , Sm, and the like. This rare earth element mainly has the effect of improving the stress corrosion cracking resistance of the alloy. In view of this effect, all of the rare earth elements can be evaluated as substantially equivalent to each other in the present invention. Therefore, one or more of them can be used in any combination, but if the total content of these in the alloy is less than 0.5%, it is insufficient to improve the stress corrosion cracking resistance. If the content exceeds 10%, many coarse crystallized substances will be generated in the alloy, leading to a decrease in strength. The most suitable content range I4 is approximately 2.0 to 7.0% when cost is also taken into account.

Mn, Cr, and Zr, which are optional components, are all useful for refining crystal grains, and Mn: less than 0.1%,
Cr: less than 0.05%, Zr: less than 0.05%, the above effects are poor, Mn: more than 0.8%, Cr: 0.3%
If Zr exceeds 0.25%, a large amount of coarse crystallized substances will be generated in the alloy, resulting in a decrease in the strength of the alloy.

Effects of the Invention As can be understood from the above, the aluminum alloy according to the present invention has high strength almost comparable to conventional rollable high-strength aluminum alloys for rolling materials, and has excellent rolling workability. Becomes excellent. In addition, since it does not contain a large amount of Cu, it has good weldability,
In addition to being usable as a welded structural material, it also has excellent stress corrosion cracking resistance due to the inclusion of rare earth elements, making it possible to commercialize a high-strength aluminum alloy with good productivity as a rolled material. This makes it possible to suitably meet the demands for thinner walls, lighter weight, and smaller size in rolled material applications.

Note that the alloy of the present invention can also be suitably used for hot forging.

Example Alloys with various chemical compositions shown in Table 1 were made into a sheet with a thickness of 55# and a width of 1
It was cast in a water-cooled mold at 50 m and then homogenized at 460'C for 12 hours. After that, excavation was made to a thickness of 50m,
This was hot-rolled at 450'C to a thickness of 3M, and the rollability was evaluated by the number of passes at that time, and the performance was measured for stress cracking resistance and tensile strength. The results are shown in Table 2.

Margin below U] Table 2 *1... Number of hot rolling baths from thickness 5071111 to thickness 3#1l11.

*2... In a 3.5% Na Cfl aqueous solution, a stress of 20 KjJf/(Bd) was applied to the test piece in the rolling direction, and the number of days until cracking occurred was measured.

*3...T6 material solution treatment condition: 460°C x 2 hours → water cooling artificial aging treatment condition: 120°C x 24 hours As seen in the results in Table 2 above, the alloy according to the present invention is in the range of aluminum alloys that contain a high percentage of Zn and a relatively low content of Mg, and although it has high strength as its inherent property, it has a high strength compared to the comparative example alloy. It can be seen that it has excellent properties in terms of rolling properties and stress corrosion cracking resistance. Moreover, the alloy according to the present invention had finer grains than the comparative alloy, and had excellent hardenability and weldability.

Above - and 1 October 18, 1985 Patent Application No. 185472 2 Name of the invention High-strength aluminum alloy with excellent rolling workability 3 Relationship with the amended person's case Patent applicant address Sakai City 6-224 Kaizancho Name Showa Aluminum Co., Ltd. Fallen Ishii
Parent 4, agent address: Shinsaibashi Iwasaki Building, 72-4 Unagidani Nakanocho, Minami-ku, Osaka, 5.1.・Name (7118) Patent Attorney Daiyoshi Shimizu.

(06) 245-2718 -1''5, Date of amendment order (voluntary amendment) 6, Number of inventions increased by amendment 7, Table 2 stated on page 10 of the specification subject to amendment in attached sheet i 'Isu, revise, correct.

(Attachment) Table 2

Claims (2)

[Claims] (1), Zn: 4-12% Mg: 0.3-2.5% One or more rare earth elements :0.5~10% and, if necessary, Mn: 0.1-0.8% Cr: 0.05-0.30% Zr: 0.05-0.25% Contains one or more of the following, with no residual Part consists of aluminum and unavoidable impurities High-strength aluminum alloy with excellent rolling workability Money. (2), Zn: 4-12% Mg: 0.3-2.5% Cu: 0.05-0.7% One or more rare earth elements :0.5~10% and, if necessary, Mn: 0.1-0.8% Cr: 0.05-0.30% Zr: 0.05-0.25% Contains one or more of the following, with no residual Part consists of aluminum and unavoidable impurities High-strength aluminum alloy with excellent rolling workability Money.