JPS6136578B2 - - Google Patents

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, and 7010 alloy are known as high-strength aluminum alloys that can obtain a tensile strength of 60 Kg/mm ² , but these alloys have large amounts of Cu and Mg and have poor extrudability. bad. Also, Al
The toughness is low because the second group of -Cu-Mg compounds are crystallized. Therefore, when using these alloys to process extruded materials that require drawing, such as motorcycle rims,
When drawing for spoke mounting parts, cracks may occur in the material, and even if no cracks are observed during drawing, load tests (compressive loads are applied in the diametrical direction while the rim shape is in place, and the strength at the time of fracture deformation) After the test), cracks occur in the drawing area, making it more likely to break. That is, it can be pointed out that the above alloy has low fracture toughness. The purpose of the present invention is to solve the problems of the conventional high-strength alloys and to obtain one with good extrudability and excellent strength and toughness. less than 7.1%, Mg1.2% to less than 2.1%,
Cu1.3%~less than 1.7%, Mn0.11%~0.50%, Zr0.06
Contains %~0.20%, Ti0.01%~0.15%, and
Contains one or both of 0.05% to 0.30% Cr and 0.05% to 0.20% V, with the remainder consisting of Al and inevitable impurities.It has good extrudability and excellent strength and toughness. Made of high strength aluminum alloy. In the present invention, Zn helps improve strength, but
If it is less than 4.6%, a tensile strength of only 50 Kg/mm ² or less can be obtained, and if it is 7.1% or more, a tensile strength of 70 Kg/mm ² or more can be obtained, but the stress corrosion cracking susceptibility is high and it cannot be used practically. Mg is related to extrudability and increases strength, but 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. or,
At 1.7% or more, the amount produced varies depending on the amount of Mg, but
The second phase tends to crystallize and deteriorates toughness. 〓〓〓〓
When Mn exceeds 0.50%, hardenability is inhibited, and Mn
If it is less than 0.11%, the structure will not become fibrous, and there will be no effect on stress corrosion cracking resistance. When Zr exceeds 0.20%, Zr-based compounds are crystallized,
If it is less than 0.05%, the structure will not become fibrous and there will be no effect on stress corrosion cracking resistance. When Ti exceeds 0.15%, Ti-based compounds tend to crystallize, and when it is less than 0.01%, it has no effect on refining the casting structure. Both Cr and V refine recrystallized grains, and contain one or both of them, but in the case of Cr, if it exceeds 0.30%, Cr-based compounds will crystallize, and 0.05%
If it is less than %, there is no effect on stress corrosion cracking resistance. Further, when V exceeds 0.20%, V-based compounds tend to crystallize, and when it is less than 0.05%, it is not effective in refining the structure. It is preferable that the amount of impurities be as small as possible so as not to impair toughness. In particular, Fe is 0.15% or less, and Si is
It is preferably 0.12% or less. Next, specific examples will be described. Alloy materials having the compositions shown in Table 1 were prepared. The remainder of each alloy is Al and unavoidable impurities.

[Table] Each of the above alloy materials was formed 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 mm and a width of 120 mm was formed. In addition to the extrudability (extrusion speed) at that time, it is further water quenched after solution treatment for 460 x 2 hours, and then
The mechanical properties of the material tempered at 150°C were tested by shear cracking, cracking by drawing during treatment of O material, and cracking by load testing of material processed into the shape of a motorcycle rim. The results of these tests are shown in Table 2. The shear cracking test is a test method in which an extruded shape is shear cut along the extrusion direction, and then boiled in chromic acid to check for cracks on the cut surface. This is a simple test method to determine. A case where no cracking occurred in multiple tests is indicated by ○, a case where the number of cracks was 50/50 is △, and a case where almost no cracking occurred is indicated by ×. 〓〓〓〓
In the crack test by drawing, the diameter of drawing is 16
A ball of mmφ is attached to a press, and the ball is pressed against a shaped material and drawn. ○ indicates that no cracks occur even if the ball is extended to a height of approximately 4 to 9 mm, and △ indicates that there is no cracking or no cracking, or 50/50 indicates almost no cracks. Cases of cracking are indicated by ×. In the load-induced cracking test, a material is bent into a circle and welded at both ends to form the shape of a motorcycle rim. A load is applied in the diametrical direction to deform the material, and the test is performed to determine whether cracks occur and break when deformed. In the investigation method, cases in which no breakage occurred even after multiple tests are shown as ○, and cases in which almost all breakage occurred are shown as ×.

[Table] As is clear from the results shown in Table 2 above, the alloy of the present invention has good extrudability, is a material with excellent strength and toughness, and can be easily processed, for example, by using it for manufacturing motorcycle rims. Moreover, it is possible to manufacture products with excellent performance. 〓〓〓〓

Claims (1)

[Claims] 1 Zn4.6% to less than 7.1%, Mg1.2% to less than 2.1%,
Cu1.3%~less than 1.7%, Mn0.11%~0.50%, Zr0.55
%~0.20%, Ti0.01%~0.15%, and
Contains one or both of 0.05% to 0.30% Cr and 0.05% to 0.20% V, with the remainder consisting of Al and inevitable impurities. Good extrudability and excellent strength and toughness. High strength aluminum alloy.