JPS5928555A - High tensile aluminum alloy good in extrudability and excellent in strength and toughness - Google Patents

Abstract

PURPOSE:To obtain a high tensile Al alloy good in extrudability and excellent in strength and toughness, by specifying the content of Zn, Mg, Cu, Mn, Zr, Ti, Cr and V in Al. CONSTITUTION:This high tensile Al alloy contains 4.6-7.1% Zn, 0.12% <=Mg< 2.1%, 1.3% <=Cu<1.7%, 0.11-0.50% Mn, 0.06-0.20% Zr and 0.01-0.15% Ti as well as one kind or more 0.05-0.30% Cr and 0.05-0.20% V and the remainder Al. In this case, impurities is pref. to be as litile as possible in order not to inhibit toughness. Especially, Fe is pref. about 0.15% or less and Si is 0.12% or less.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved high-strength aluminum alloy that has good extrudability and excellent strength and toughness.

Conventionally, 7075 alloy, 7050 alloy, 7010 alloy, etc. are known as high-strength aluminum alloys that can obtain a tensile strength of 60 to 8/-, but these alloys have a high content of Cu and Mgm and have poor extrudability. bad. Also, A℃ −
The toughness is low because it is difficult to crystallize the CU-MO type second phase compound. For this reason, these alloys can be used to manufacture J-type products that require drawing processing using extruded materials, such as auto-high rims.
:When processing a material such as a rim, when drawing it as a spoke attachment part, cracks may occur in the material, or even if no cracks are observed during the drawing process, a load test (compressive load applied in the diametrical direction while the rim shape is still in place) may occur. In addition, after a test to check the strength during destructive deformation), cracks occur in the drawing area and the product becomes prone to breakage. That is, it can be pointed out that the above alloy has low fracture toughness.

The present invention aims to solve the problems of the conventional high-strength alloys and obtain one with good extrudability and excellent strength and toughness. 1.
Less than 1%, MQ 1.2% to less than 2.1%, Ctl 1
．． 3% to less than 1.7%, M n0111% to 0.50%
, ZrO, 06%~0.20%, T i O, 01%~
Contains 0.15%, and Cr0.05% to 0.30%,
It is characterized by containing one or two of VO, 05% to 0.20%, and the remainder consisting of Δρ and unavoidable impurities.It has good extrudability and is superior in strength and toughness. High strength aluminum alloy.

In the present invention, Zn is useful for improving strength, but 4.6%
If the tensile strength is less than 56 kg/■-, the tensile strength will be less than 56 kg/■-
If it is 7.1% or more, the tensile strength will be increased by 70 kg/- or more, but the stress corrosion cracking susceptibility will be high and it cannot be used practically.

IVH+ is related to extrudability and increases strength, but it is 1.2%
If it is less than 2.1%, extrudability is good but high strength cannot be obtained, and if it is more than 2.1%, extrudability is poor and productivity is inhibited.

If Cu is less than 1.3%, high strength cannot be obtained and there is a problem in terms of stress corrosion cracking in the thickness direction.

Moreover, if it exceeds 1.7%, the second phase tends to crystallize and the toughness deteriorates, although the amount of M(I) produced varies depending on the amount of M(I).

When Mn exceeds 0.50%, the hardenability is inhibited and Mn-based compounds tend to crystallize, while when it is less than 0.11%, the structure does not become fibrous and has no effect on R1 stress corrosion cracking properties.

When 7r exceeds 0.20%, Zr-based compounds are crystallized, and when it is less than 0.05%, the structure does not become fibrous and has no effect on stress corrosion cracking resistance.

If 1-1 exceeds 0.15%, the 1-1 compound tends to crystallize, and if it is less than 0.01%, the effect of refining ♀/I silk fabric is poor.

Both Cr and V refine recrystallized grains, so they contain one or both of them, but in the case of Cr, it is 0.30%.
If it exceeds 0.05%, Cr-based compounds will crystallize, and if it is less than 0.05%, it will have no effect on stress corrosion cracking resistance. Also, ■ is 0.20%
If it exceeds 0.05%, the (2) type compound will crystallize, and if it is less than 0.05%, it will not be effective in refining the structure.

It is preferable that the amount of impurities be as small as possible so as not to impair toughness. Especially Fe is 0.15% or less, 3i is 0.12
% or less is preferable.

Next, specific examples will be described.

Alloy materials having the compositions shown in Table 1 were prepared. The remainder of each alloy is 8ρ and unavoidable impurities.

Each of the above-mentioned alloy materials was made into a billet with a diameter of 8 inches and a length of 500 mm, and after soaking at 400 to 500°C for 24 hours, an extruded shape with a thickness of 6 inches and a width of 120 nm+m was formed. In addition to the extrudability (extrusion speed) at that time, the mechanical properties of the material, the shear cracking test, and the drawing process during treatment of O material are further determined by water quenching after solution treatment at 460℃ x 21-4R, and further tempering at 150℃. A cracking test and a cracking test using a load test using a material processed into the shape of a motorcycle rim were conducted. The results of these tests are shown in Table 2.

The Sissy crack test is a test method in which an extruded material is shear cut along the extrusion direction, and then boiled in chromic acid to check for curling on the cut surface. This is a simple test method to determine cracks. Cases in which no cracking occurred in a plurality of tests are shown as 01, cases in which cracks did not occur, or 50/50 were △, and cases in which cracks occurred most of the time are shown as ×.

A cracking test by drawing shows that in the drawing process, a ball with a diameter of 16mm is attached to a press, and the ball is pressed against the shape and drawn.No cracks occur even when the ball is extended to an opening height of approximately 4~G. ○ indicates the case, △ indicates the case where there is no cracking or no cracking, and × indicates the case where there is almost no cracking.

In the load-induced cracking test, a shape is bent into a circle and both ends are welded to form a motorcycle rim, and a load is applied to the shape in the diametrical direction to deform it. In this method, cases where no breakage occurs even after multiple tests are performed are indicated by ○, and cases where most of the tests are broken are indicated by ×.

Table 2 It is clear from the results shown in Table 2 above that the J3 alloy of the present invention has good extrudability, and is a material with excellent strength and toughness. This makes it possible to manufacture products that are easy to process and have excellent performance.

Patent applicant: Sumitomo Light Metal Industries, Ltd. Agent Patent Attorney Hide Komatsu

Claims (1)

[Claims] 1, Zn4.6%~less than 7.1%, M(+1.2
% to less than 2.1%, (:), u 1.3% to less than 1.7%, Mn0011% to 0.50%, Zro, 06% to 0
．． 20%, Ti 0.01% to 0.15%, and
Oro, 05%~0.30%, VO, 05%o~0.
A high-strength aluminum alloy with good extrudability and excellent strength and toughness, characterized by containing 20% of one or both of the above, and the remainder consisting of AJ2 and unavoidable impurities.