JPS61183434A - Hydrostatic extruded high strength al-mg aluminum alloy for cold forging - Google Patents

Abstract

PURPOSE:To obtain the titled Al alloy of non-heat-treated type excelling in strength and forgeability by manufacturing an Al alloy containing specific percentage of Mg, Zn, and Zr and having fine and uniform equi-axed crystal structure of specific dimensions by hydrostatic extrusion. CONSTITUTION:The Al alloy consisting of, by weight, 6.0-12% Mg, 0.05-2.0% Zn, 0.05-0.3% Zr and the balance essentially Al, and further containing as required 1 or >=2 kinds among <=1.5% Mn, <=0.03% Cr and <=2.0% Cu, and composed of <=30mu fine an uniform equi-axed crystal structure is manufactured by hydrostatic extrusion. This alloy may contain <= about 0.3% Fe, <= about 0.2% Si, <= about 0.01% Be, <= about 10% TiO, and <= about 0.01% B. In this way, an Al-Mg alloy having superior mechanical properties can be obtained without deteriorating its excellent cold forgeability.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to isostatically extruded high-strength Al-Mg for cold forging.
More specifically, the present invention relates to a high-strength Al--Mg-based aluminum alloy for cold forging, which is manufactured by hydrostatic extrusion and is non-heat-treated and has excellent strength and forgeability.

[Prior Art 1] In general, Al-Mg-based aluminum alloys are non-heat treatable alloys with excellent mechanical properties, and in particular, 5056 alloy and the like are widely used.

This alloy is used to produce cold forging bars and the like by conventional extrusion such as direct extrusion or indirect extrusion.

However, although the extruded material of the above-mentioned 5056 alloy has good cold forgeability, it has low strength, and in the conventional extrusion currently being used, the extrusion limit is the composition of the 5056 alloy. It is unsuitable for the demand for aluminum alloys with high strength and formability.

[Problem to be Solved by the Invention 1] As explained above, the present invention provides a hydrostatic forging method that has excellent mechanical properties without impairing the excellent cold-opening forgeability of the conventionally used 5056 alloy. The present invention provides an extruded high-strength Al-Mg-based aluminum alloy for cold open forging.

[Means for Solving the Problems 1] Isostatically extruded high strength Al for cold open forging according to the present invention
The Mg-based aluminum alloy contains (1) Mg6.0-12wt%, Zn 0.05-2.
0wt%, Zr 0.05-0.3wt%, the remainder being substantially Al, and having a fine uniform equiaxed crystal structure of 30μ or less. The first invention is a high-strength AI-M, based aluminum alloy for cold-glazed GL construction, (2) Mg 6.0-12wt%, Zn 0.05
-2.0wt%, Zr 0.05-0.3wt%, and further contains Mn 1.5wt% or less, Cr 0.30wt% or less,
Cu 2. Hydrostatic pressure characterized by being an aluminum alloy containing one or more selected from O+t% or less, the remainder being substantially Al, and having a fine uniform equiaxed crystal structure of 30μ or less This invention consists of two inventions, with the second invention being an extruded high-strength Al-Mg-based aluminum alloy for cold forging.

Hydrostatically extruded high strength Al- for cold forging according to the present invention
The Mg-based aluminum alloy will be explained in detail below.

First, the components and component ratios of the hydrostatically extruded high-strength Al-Mg-based aluminum alloy for cold-open forging according to the present invention will be explained.

Mg is an essential element for increasing strength and cold forgeability, especially deformability, and the content is 6. If the content is less than Ou+t%, extrusion by normal extrusion is possible, but the required strength cannot be obtained, and if the content exceeds 12u+t%, extrusion cracks will occur even by hydrostatic extrusion, making extrusion impossible. . Therefore, the Mg content is 6.0 to 12
Let it be wt%.

Zn is an element that improves strength and stress corrosion cracking resistance. If the content is less than 0.05 wt%, these effects will be small, and if the content exceeds 2.0 wt%, cold forgeability, especially Deformability deteriorates rapidly. Therefore, the Zn content is set to 0.05 to 2.0 wt%.

Zr is an element that improves strength, cold-opening forgeability, especially deformability and stress corrosion cracking resistance, and the content is 0.05a+
If it is less than t%, these effects are small, and if it is less than 0.3wt
If the content exceeds %, coarse Al-Zr compounds are generated, which rapidly deteriorates cold forgeability, especially deformability. Therefore, the Zr content is set to 0.05 to 0.3 wt%.

Mn and Cr are elements that contribute to improving strength and stress corrosion cracking resistance, and Mn 1.5 wt%, Cr
When each content exceeds 0.30+ut%, coarse intermetallic compounds are likely to be formed with AI, and cold forgeability, especially deformability, is severely deteriorated. Therefore, the Mn content is 5w
t% or less, and the Cr content is 0.30Illt% or less. Note that the minimum content of Mn and Cr in order to exhibit the above effects is preferably 0.05 wt% for both Mn and Cr.

Cu is an element that contributes to improving strength and stress corrosion cracking resistance, and if the content exceeds 2.0 wt%, it impairs corrosion resistance and deteriorates cold forgeability, especially deformability. . Therefore, the Cu content is 2. Let Ou+t%. Note that the minimum content for exhibiting the above effects is 0.05 IIlt%.

Other impurities include Fe-containing i of 0.3 wt% or less,
A Si content of 0.2 u+t% or less does not impede the performance of the hydrostatically extruded high-strength Al-Mg-based aluminum alloy for cold forging according to the present invention, and is therefore permissible within the above range.

In addition, when the hydrostatically extruded high-strength Al-Mg-based aluminum alloy for cold forging according to the present invention has a high Mg content, Be is set to 0 to prevent oxidation loss of Mg during melting. It may be contained in an amount of .01u+t% or less, and furthermore, Tie for grain refinement.

10...L% or less, B 0.01u+t% or less can be contained.

Regarding the structure of the isostatically extruded aluminum alloy material explained in - above, by making it a fine and uniform equiaxed crystal MLm, it is possible to increase the strength and extremely excellent cold forgeability (especially deformability). was found to have 3
The above effects can be achieved by forming fine uniform equiaxed crystals with a diameter of 0μ or less, but if the diameter exceeds 30μ, cold-opening forgeability (particularly deformability) and strength become inferior. Therefore, the size of the equiaxed crystal is preferably 30 μm or less, and the smaller the size, the more effective it is.

[Example 1] Next, an example of the hydrostatically extruded high-strength Al-Mg-based aluminum alloy for cold forging according to the present invention will be described.

EXAMPLE An aluminum alloy having the components and proportions shown in Table 1 was melted and cast according to a conventional method to form an ingot with a diameter of 68 mm.

After soaking this ingot under the conditions shown in Table 2, it was extruded using a 400T isostatic extrusion press at an extrusion ratio of 9.4.
, extrusion speed 3IIl/min, extrusion temperature 2 under the conditions shown in Table 2.
It was extruded into a round bar with a diameter of 2 mm.

The structure of the as-extruded bar was investigated, and a tensile test and a cold forging test were conducted.

The cold forging test was performed using 10allIlφX10 from the above bar material.
A cylindrical test piece of mmH was cut out and subjected to a drop hammer test to investigate the deformation resistance at around a processing rate of 50% and the limit processing rate (deformability) until cracking occurred.

Table 3 shows the results.

Table 3 also shows 5056 directly extruded material for comparison.

From this Table 3, it is found that the hydrostatically extruded high strength Al-Mg based aluminum alloy for cold forging according to the present invention A%B and c
/C all exhibit uniform fine equiaxed crystals of 10μ, have excellent cold forgeability (especially deformability) and strength, and are said to have excellent performance as cold-open silver making materials. Recognize.

[Effects of the Invention 1] As explained above, the high-strength Al-Mg-based aluminum alloy for cold forging which is hydrostatically extruded according to the present invention has the above-mentioned structure, and therefore has good hydrostatic extrudability. It also has the effects of being a non-heat-treated type with high strength, cold-opening forgeability, and particularly excellent deformability.

Claims (2)

[Claims] (1) Mg6.0-12wt%, Zn0.05-2.0
wt%, Zr0.05 to 0.3 wt%, the remainder being substantially Al, and having a fine uniform equiaxed crystal structure of 30μ or less. High strength Al-Mg aluminum alloy for cold forging. (2) Mg6.0-12wt%, Zn0.05-2.0
wt%, Zr0.05-0.3wt%, and further contains Mn1.5wt% or less, Cr0.30wt% or less, Cu
An aluminum alloy containing one or more selected from 2.0 wt% or less, with the remainder substantially consisting of Al, and having a fine uniform equiaxed crystal structure of 30 μ or less A high-strength Al-Mg-based aluminum alloy for cold forging that is hydrostatically extruded.