JPS6237706B2 - - Google Patents

Description

[Detailed description of the invention]

Industrial Application Fields This invention relates to high-strength aluminum alloys with excellent cold workability, especially aluminum alloys used in high-strength materials that require cold working such as stretch processing, such as motorcycle rim materials. - Regarding Zn-Mg-Cu alloys. Prior Art Aluminum alloys, such as those used for rim materials for motorcycles, have excellent strength and corrosion resistance, and in addition, they must be formed with recesses for attaching spokes by extrusion processing. ,
It is also required to have excellent cold workability. However, Al-Zn-Mg-Cu alloys, which are conventionally known as high-strength aluminum alloys, have poor cold workability even in a tempered state that is easy to process, such as a solution treated state or a so-called O-material state, and the above-mentioned stretch processing is difficult. There is a drawback that cracks are likely to occur due to such factors. Problems to be solved by the invention After various studies on the cause of this problem, it was found that Al-Zn
- It has been found that Mn and Cr, which are usually added to adjust the crystal grain shape, have an adverse effect on Mg-Cu alloys. On the other hand, as conventional alloys, Al-Zn-Mg-Cu alloys containing Zr instead of Mn and Cr, such as A7050
Although such alloys are known, it has been found that these alloys still have poor cold workability such as stretch processing due to the excessive amount of Cu. This invention is based on the above findings, especially
By regulating the content of Mn and Cr and also limiting the content of Cu to a specific range, it simultaneously satisfies both properties: high strength and excellent cold workability, especially stretch workability. The present invention aims to provide an aluminum alloy that also has the required performance in terms of corrosion resistance, stress corrosion cracking resistance, extrudability, etc., which are required from a practical standpoint. Means for Solving the Problems For the above purpose, the high strength aluminum alloy with excellent cold workability according to the present invention has the following properties: Zn: 5.5 to 10.0% Mg: 1.5 to 2.2% Cu: 0.65 to 2.0% Zr: 0.05 to 0.25%, and one or more of Ti: 0.001 to 0.1%, V: 0.05 to 0.25%, B: 0.0001 to 0.08%, or further, Mn: 0.08% or less, Cr: 0.1 % or less, and the remainder consists of aluminum and unavoidable impurities. In this specification, all "%" are expressed on a weight basis. The significance of the components contained in the aluminum alloy and the proportions thereof according to the present invention will be explained as follows. Zn is an essential element for increasing the strength of alloys as a hardening element, and if it is less than 5.5%, its effect is small, and if it is contained in a large amount exceeding 10.0%, corrosion cracking resistance deteriorates. The most preferable Zn content range is about 6.0 to 8.0%. Mg, like Zn, is an essential component for increasing strength; if it is less than 1.5%, its effect is small, and if it is contained in more than 2.2%, it does not contribute much to improving strength, and vice versa. This results in the disadvantage of reduced cold workability and hot workability. The most preferable content range is about 1.6 to 1.8%. Cu is an important element that is essential for improving stress cracking resistance at the same time as improving strength, but if it is less than 0.65%, its effect is small, and if it exceeds 2.0%, cold workability decreases and strength is improved. The contribution to this is also small. The most preferable range is about 0.7 to 1.5%. Zr is effective in suppressing coarse recrystallization in the alloy, stabilizing the structure by forming a fibrous structure in the crystal grain shape, and improving stretchability, but if it is less than 0.05%, the less effective,
If it exceeds 0.25%, coarse crystallized substances will be formed and the toughness will deteriorate. The most preferred range is 0.1-0.15%
That's about it. Although Mn is originally effective in adjusting grain shape, its addition tends to deteriorate cold workability. However, if it is less than 0.08%,
Its harmful effects are low. Cr, like Mn, is effective in adjusting grain shape, but on the other hand it degrades cold workability, but if it is 0.1% or less, the effect is small. Ti, V, and B are all effective for stabilizing the structure, and at least one of them should be added to Ti0.001% or more, V0.05% or more,
This effect can be obtained by containing a small amount of B0.0001% or more. However, if too many of them are contained, the extrudability etc. will be deteriorated, so Ti0.1
% or less, V0.25% or less, and B0.08% or less. Effects of the Invention As is clear from the following examples, the aluminum alloy according to the present invention is superior to various conventionally known comparative alloys in terms of mechanical properties such as tensile strength, yield strength, and elongation. While possessing properties that are not inferior to, in fact, superior to,
It has excellent cold workability such as overhang processing,
It can be suitably used not only as a rim material for motorcycles, etc., but also as a material for various applications that require high strength and ductility due to the need for cold working such as bending, pressing, drawing, and ironing. It is. The alloy according to the present invention can be used not only as an extruded material like the rim material described above, but also as a sheet material. Next, examples of this invention will be shown. Example

[Table] Extruded materials of aluminum alloys with the various chemical compositions shown in Table 1 (the remainder is aluminum) were solution-treated at 470°C for 1 hour, cooled with water, and then heated at 120°C for 24 hours. The sample was subjected to time aging treatment. And for each sample,
When we investigated its mechanical properties and stretchability, we found that
The results were as shown in Table 2 below.

【table】

[Table] In Table 2 above, the overhang workability is as follows:
The height of the overhang until the sample cracks was measured when an extruded material with a wall thickness of 6 mm was used as a sample and overhanged into a spherical shape using an Erichsen machine with a punch of 17 mm in diameter. In addition, all evaluations were made based on the use as a rim material, and were shown as 〇: Good, △: Fairly good, ×: Not good.

Claims (1)

[Claims] 1 Contains Zn: 5.5-10.0% Mg: 1.5-2.2% Cu: 0.65-2.0% Zr: 0.05-0.25%, and Ti: 0.001-0.1% V: 0.05-0.25% B: 0.0001 A high-strength aluminum alloy with excellent cold workability, characterized in that it contains one or more of the following: ~0.08%, with the remainder consisting of aluminum and unavoidable impurities. 2 Contains Zn: 5.5 to 10.0% Mg: 1.5 to 2.2% Cu: 0.65 to 2.0% Zr: 0.05 to 0.25%, and contains one or two of the following: Mn: 0.08% or less Cr: 0.1% or less , and further contains one or more of Ti: 0.001-0.1%, V: 0.05-0.25%, and B: 0.0001-0.08%, with the remainder consisting of aluminum and inevitable impurities, and has cold workability. High strength aluminum alloy with excellent properties.