JP2001011557A - Cold forging stock of aluminum alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obviate the necessity of thermal refining after cold forging and to attain cold forging of high forging ratio by providing a composition consisting of specific amounts of Si, Mg, Cu, and Cr and the balance Al with inevitable impurities and also regulating grain size to a specific value or below. SOLUTION: The cold forging stock of aluminum alloy has a composition containing, by weight, 0.040-0.46% Si, 0.80-0.86% Mg, 0.32-0.40% Cu, and 0.04-0.35% Cr and also has <=200 μm grain size. In order to regulate the grain size of the cold forging stock to <=200 μm, either of the following procedures (1), (2) are carried out: (1) in the case where the stock is manufactured by the direct extrusion method, billet temperature and product speed are regulated to 490-530 deg.C and (8 to 20) m/min, respectively, and rapid cooling is done by means of water cooling, or the like, immediately after extrusion; (2) in the case of indirect extrusion, billet temperature and product speed are regulated to 330-370 deg.C and (10 to 20) m/min, respectively, and heating is performed at 520-530 deg.C for 1-4 hr after extrusion and rapid cooling is done by means of water cooling, or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold forging material made of an aluminum alloy.

[0002]

2. Description of the Related Art For example, JIS having excellent ductility is used as a material for cold forging of an aluminum alloy for manufacturing a hub material for an aluminum alloy hard disk by cold forging.
An A6061 O or T1 material was used.

[0003]

However, since the final temper of a forged product manufactured from a conventional material is required to be T6, after forging, a solution treatment and an artificial aging treatment are performed. Necessary. By the way, usually
Forgings manufacturers only purchase materials from material manufacturers and perform forging, and outsource refining consisting of solution treatment and artificial aging treatment, which increases the cost. was there.

Therefore, it has been considered that cold forging is performed using a cold forging material made of JIS A6061-T4 material to omit tempering after forging.
The T4 material has poor ductility and may cause cracking during cold forging, so that there is a problem that only cold forging with a low forging ratio can be performed.

[0005] An object of the present invention is to provide an aluminum alloy cold forging material which solves the above-mentioned problems, eliminates the need for tempering by heat treatment after cold forging, and can perform cold forging with a high forging ratio. It is in.

[0006]

The aluminum alloy cold forging material according to the present invention is made of Si0.4.
0-0.46% by weight, Mg 0.80-0.86% by weight,
Cu 0.32 to 0.40% by weight, Cr 0.04 to 0.3
An aluminum alloy containing 5% by weight, the balance being Al and unavoidable impurities, and having a crystal grain size of 200 μm or less.

The reasons for limiting the alloy components in the aluminum alloy used as the material in the cold forging material of the present invention are as follows.

[0008] The upper limit of the content of Si and Mg is JIS A
It is smaller than the upper limit of the content of Si and Mg in 6061, and the lower limit is the same as the lower limit of the content of Si and Mg in JIS A6061. Si and M
g, like Si and Mg in JIS A6061, forms Mg ₂ Si and acts to improve mechanical properties, but when the content is less than the lower limit, such effects cannot be obtained. . Further, when the content of Si and Mg exceeds the upper limit, grain boundary precipitates are generated and ductility is reduced, and as a result, cracks may occur during cold forging, and a forged product having a high forging ratio is obtained. You can't get it. Therefore, the Si content should be selected within the range of 0.40 to 0.46% by weight, and the Mg content should be selected within the range of 0.80 to 0.86% by weight. Note that the upper limit of the content of Si and Mg is smaller than the upper limit of the content of Si and Mg in JIS A6061.
There is a possibility that the strength is reduced as compared with 061.

The upper limit of the content of Cu is the same as the upper limit of the content of Si and Mg in JIS A6061.
The lower limit is larger than the lower limits of the contents of Si and Mg in JIS A6061. Cu is Si and Mg
Acts to obtain the required strength by compensating for the decrease in strength due to the upper limit of the content of the above as described above, but if the content is less than the lower limit, this effect is not obtained, the required strength Can not get. On the other hand, when the Cu content exceeds the upper limit, the corrosion resistance decreases. Therefore, the Cu content should be selected within the range of 0.32 to 0.40% by weight.

[0010] The content of Cr is the same as the content of Cr in JIS A6061, and its function is also JIS A6061.
The purpose of the present invention is to suppress the generation of coarse recrystallized grains, similarly to the function of Cr in the above.

In the material for cold forging of the present invention, the crystal grain size is limited as described above because the crystal grain size is 200
If the thickness exceeds μm, the ductility decreases. In order to reduce the crystal grain size of the material for cold forging to 200 or less, if the material is manufactured by direct extrusion, the billet temperature is set to 49.
It is preferable that the temperature is 0 to 530 ° C., the product speed is 8 to 20 m / min, and the material is rapidly cooled by water cooling or the like immediately after extrusion. If the material is manufactured by the indirect extrusion method, the billet temperature is set to 330 to 370 ° C. and the product speed is set to 10 to 2
0 m / min, and after extrusion at 520-530 ° C.
It is preferable to perform a solution treatment in which the solution is rapidly cooled by heating with water or the like for about 4 hours.

According to the cold forging material of the present invention, JIS
The strength and corrosion resistance of the material made of A6061 are not impaired. Moreover, since the ductility has been improved,
Also in 4, forgings having a high forging ratio can be formed by cold forging without cracking. As a result, forging manufacturers do not need to perform tempering after forging. In addition, the cost is lower than when outsourcing forging after forging.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described together with comparative examples.

Example 1 0.44% by weight of Si, 0.80% by weight of Mg, 0.3% of Cu
Using an extrusion billet comprising an aluminum alloy containing 4% by weight, the balance being Al and unavoidable impurities, a billet temperature of 350 ° C. and a product speed of 2 were obtained by indirect extrusion.
The extruded profile of temper T1 produced under the condition of 0 m / min
A material for cold forging of temper T4 was manufactured by applying a solution treatment of heating at 5 ° C. for 1 hour and then cooling with water.

Example 2 0.44% by weight of Si, 0.80% by weight of Mg, 0.3% of Cu
Using an extrusion billet comprising an aluminum alloy containing 4% by weight, the balance being Al and inevitable impurities, a billet temperature of 510 ° C. and a product speed of 10 were obtained by direct extrusion.
Extrusion molding was performed under the conditions of m / min, and the material was cooled with water immediately after extrusion to produce a material for cold forging of temper T4.

Comparative Example Si 0.70 wt%, Mg 1.0 wt%, Cu 0.20
% By weight, using a billet for extrusion made of an aluminum alloy consisting of the balance of Al and unavoidable impurities, by a direct extrusion method, at a billet temperature of 510 ° C. and a product speed of 10 m.
Extrusion molding was performed at a rate of / min, and the material was cold-cooled immediately after extrusion to produce a tempering T4 cold forging material.

Evaluation Test The crystal grain sizes of the cold forging materials of Examples 1 and 2 and Comparative Example were measured, and their tensile strength (σ _B ) and elongation (δ) were measured. Table 1 shows the results.

[0018]

[Table 1]

As is clear from Table 1, the elongation of the materials of Examples 1 and 2 is larger than that of the material of Comparative Example, and
The average elongation (38%) of JIS A6061-O material is equivalent to that of JIS A6061-O material. Like for JIS A6061-O material, cold forging is used to form a forged product with a high forging ratio without cracking. I understand. Examples 1 and 2
The tensile strength of the material of Comparative Example was equivalent to that of the material of Comparative Example.

Claims (1)

[Claims] 1. 0.40 to 0.46% by weight of Si, Mg
0.80 to 0.86% by weight, Cu 0.32 to 0.40% by weight, Cr 0.04 to 0.35% by weight, the balance being Al
And a material for cold forging made of an aluminum alloy comprising an aluminum alloy comprising unavoidable impurities and having a crystal grain size of 200 μm or less.