JPS60138039A - Al-mg-si type delayed age hardening aluminum alloy for forging - Google Patents

Abstract

PURPOSE:To obtain the titled Al alloy having superior cold forgeability, strength and extrusibility by specifying a composition consisting of Mg, Si, Sn, Cu, Ti, B, Mn, Cr, Zr and Al. CONSTITUTION:This Al-Mg-Si type delayed age hardening Al alloy for forging consists of, by weight, 0.3-0.8% Mg, 0.40-1.5% Si (Si%>Mg%), 0.01-1.0% Sn, 0.05-1.0% Cu, 0.001-0.10% Ti, 0.0001-0.01% B and the balance Al with inevitable impurities or further contains one or more among <=1.0% Mn, <=0.30% Cr and <=0.30% Zr. The Al alloy has superior strength, delayed age hardenability at ordinary temp. for about 1-6 months, low deformation resistance and superior cold forgeability.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an Al-Mg-3i-based slow age hardening aluminum alloy for forging.

Recently, the use of cold forged aluminum alloys has increased, but A1-Mg-Si alloys, such as Mg
0.45 to 0.8%, Si 0.6 to 1.2wt%
The 6151 alloy containing Cu 3.5-5.0 has low deformation resistance and good cold forgeability. Al-C containing O+L%
Currently, they are being replaced by U-based alloys.

However, as a material for forging aluminum alloys, cold l
No. 11 material was used to reduce the deformation resistance during forging, and after cold forging, heat treatment of quenching and tempering was performed to improve the strength and then it was put into practical use.

However, this case has the following problems.

1) Quality abnormalities such as burning are likely to occur. 62) Hardening distortion is likely to occur in thin products.

3) Hardening equipment is required.

Therefore, as a result of repeated research, the inventor of the present invention used a material that was quenched from the beginning as a material for forging an aluminum alloy, and also made a material that delayed aging at room temperature after quenching, and performed tempering after cold forging during forging. We have found that if we put it into practical use after this process, this problem will disappear.

Based on this knowledge, the present inventors developed 6061 alloy, 61
51 alloy T6 material, i.e. σ8≧30
Kg/Kg2, σ. , 2≧25 Kg/+om2,
Al-Mg-3i type slow-age hardening type that has a slow aging hardenability of 1 to 6 months at room temperature, and has cold forgeability comparable to deformation resistance as O material of 6061 alloy and 6151 alloy. They developed an aluminum alloy for forging.

The features of the Al-Mg-3i-based slow-age hardening aluminum alloy for forging according to the present invention include Mg 0.3 to
0.8wt%, Sin, 40-1.54t%, SnO
,01-1,Ou+t%,Cu O,05-1,(bu
t% or less, TiO, 001-0. IQu+t% or less,
It contains BO,0001 to 0.01 iut% or less, and the Si content is greater than the Mg content, and furthermore, Mn 1. Contains one or more selected from Ou+L% or less, CrO, 30wt% or less, Zr 0.30u+t% or less, and the remainder is A.
1 and unavoidable impurities.

The AlMg-8i-based slow age hardening aluminum alloy for forging according to the present invention (hereinafter sometimes simply referred to as the aluminum alloy according to the present invention) will be described in detail.

First, the components and component ratios of the aluminum alloy according to the present invention will be explained.

Mg is a hardening element that improves strength by forming Mg2Si with Si. If the content is less than 0.3 Illt%, the effect of improving strength is small, and if the content exceeds 0.8 u+t%, It inhibits extrudability and cold forgeability, and also inhibits slow age hardenability by combining with Sn. Therefore, M
The g content is 0.3 to 0.811 IL%.

Si is a hardening element like Mg, and improves strength by forming Mg2Si, and the content is 0.40u+t.
If it is less than 1.5u+t, there is no effect of improving the strength.
If the content exceeds %, extrudability and cold forgeability will be inhibited. Therefore, the Si content is set to 0.40 to 1.5 wL%.

Sn is an important element for imparting slow age hardenability, and if the content is less than 0.01+ut%, the slow age hardenability is insufficient; If the content exceeds O+t%, the toughness will be impaired and cold forgeability will be inhibited. Therefore, the Sn content is set to 0.01 to 1.0 iut%.

Cu is an element that helps improve strength, and the content is 0.05
There is no such effect below u+t%, and 1.0
If the content exceeds wt%, cold forgeability will be impaired.

Therefore, the Cu content is 0.05 to 1. On+t% or less.

Ti and B are elements that refine the cast structure and extruded structure, and the content is less than TiO, 0ObIlt%, BO,
If Ti is less than 0001u+t%, this effect is absent;
If the content exceeds O,10u+t% and B2O,01u+t%, a huge intermetallic compound with A1 is formed, impairing cold forgeability. Therefore, the Ti content is 0.001
~0, Lout% or less, B content is 0.0001~0.
01u+t% or less.

The relationship between the Mg content and Si content explained above is Si>
If Mg is not used, slow age hardening properties will not be exhibited.

Therefore, the Si content is made larger than the Mg content.

Mn is an element that imparts strength, and the content is 1.0wt.
%, cold forgeability will be impaired. Therefore,
Mn content is 1. Ou+t% or less.

Both Cr and Zr are elements that improve strength, and if their content exceeds 0.30 wt%, they form a giant intermetallic compound with A1, which impairs cold forgeability. Therefore, the Cr content and Zr content should be 0.30u+L% or less.

Next, examples of the A1-Mg-3i-based slow age hardening aluminum alloy for forging according to the present invention will be described, and comparative examples will also 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 155 mm, and then homogenized at 555°C for 4 hours.
Extrusion processing was performed at a temperature of 0 to 490°C to obtain a round bar with a diameter of 18 mm.

To evaluate cold forgeability, 15n+mφX '15
Deformation resistance was determined by a drop hammer test at room temperature using a mmH cylindrical sample.

The heat treatment conditions are as follows.

0 treatment: 380°C x 2Hr- +2300 Furnace cooling quenching treatment: 530°C x 60 m1n- + Tempering conditions for W-QTG material: 175°C x 8HrT6 Strength was determined by tensile test of JIS No. 4 test piece, σ8, σ. , 2, δ was determined.

The slow aging ability was investigated by a tensile test and a drop hammer test.

These results are shown in Table 2.

As is clear from Table 2, the aluminum alloy according to the present invention has slow age hardenability after quenching, has almost the same strength as 16 of 6061 and 6151, and has the same cold forgeability as 6061 and 6151. It can be seen that the deformation resistance of the aluminum alloy according to the invention after quenching at room temperature for 1 month or 6 months is not much different from the deformation resistance of 6061 and 6151 zero materials, and has good cold forgeability.

The Al-Mg Si-based slow aging hardening type aluminum alloy for forging according to the present invention has the above-mentioned configuration and is excellent as a quenching and forging material for aluminum alloys.
It is excellent as a low-cost extruded material that has good reproducibility and strength.

Claims (1)

[Claims] M2O, 3-0, hL%, Si Q, 40-1.5wL
%, So O,01-1,0wt%, Cu O,05-
1, Ou+t% or less, Ti O, 001 to 0.1011
17% or less, BO,0001~0.01u+t% or less, and the Si content is greater than the Mg content,
Furthermore, it contains one or more selected from Mu 1.0wt% or less, CrO, 30+uL% or less, ZrO, 30wL% or less, and the remainder is A.
Al characterized by having t and unavoidable impurities)
-Mg-3i-based slow aging hardening aluminum alloy for forging.