JPS61163232A - High strength al-mg-si alloy and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a high strength Al-Mg-Si alloy having superior spinnability by adding specified amounts of Mg, Si, Cu and one or more among Cr, Mn, Zr, V, Ti and B to Al. CONSTITUTION:The composition of an Al alloy ingot is composed of, by weight, 0.4-1% Mg, 0.05-0.6% Si, 0.05-0.4% Cu, one or more among 0.05-0.4% Cr, 0.05-0.6% Mn, 0.05-0.2% Zr, 0.02-0.15% V, 0.005-0.5% Ti and 0.0005-0.05% B, and the balance Al with inevitable impurities. The alloy ingot is heated to 350-500 deg.C at <=40 deg.C/hr heating rate, held at the temp. for 2-24hr, and then held at 450-520 deg.C for 2-12hr before the ingot is hot rolled. By this two-step holding, the grain size is regulated to <=50mum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a high-strength Al-Mg-Si alloy and its manufacturing method, and more specifically, as a material for three-piece wheel rims of automobiles etc. The present invention relates to a high-strength Al-Mg-Si alloy with excellent properties and a method for producing the same.

[Prior art] So-called three-piece type wheel rims for automobiles, etc.
Most of them are manufactured by spinning.

However, currently, non-heat-treated Al-M is mainly used in terms of strength, corrosion resistance, and spinning processability.
The g-based alloys 5052 and 5154 are used.

However, with the recent improvements in performance and weight reduction of automobiles,
There is an increasing demand for thinner wheels, and high-strength materials are desired.

For this reason, 6061 is an Al-Mg-Si heat-treatable alloy that has excellent workability and corrosion resistance in soft materials.
are used in some cases, but materials with even higher strength are required.

When manufacturing wheels using Al-Mg-Si alloy, after spinning and forming the soft material into a predetermined shape, the process is followed by 'solution treatment'. A method of manufacturing high-strength wheels by quenching and T6 aging has been adopted.

The excellent mechanical properties of this Al-Mg-Si alloy are due to the precipitation of Mg2Si compounds.Furthermore, in order to improve the strength,
This is generally done by increasing the Mg and Sl contents.

However, as the Mg content increases, the deformation resistance increases and the spinning processability of soft materials becomes poor.This has led to the use of Al-MgSi as a material for high strength automobile wheel rims up to now This is the extraordinary reason why Al-based alloys did not exist, and it is also the reason why Al-
Mg-3i alloys have relatively large crystal grains, and when subjected to severe processing such as spinning, there is a problem in that the surface becomes rough and cracks occur.

[Problem to be Solved by the Invention 1] As explained above, the present invention has been developed by the present inventors in view of the fact that there is no material with excellent spinning processability and various problems with conventional materials. As a result of extensive research, we have found that this material has much better spinning processability than conventional materials as a material for 3-piece wheel rims for automobiles, etc.
We have developed a high-strength Al-Mg-3i alloy and a method for producing it.

[Means for solving the problems] The high-strength AlMg-Si alloy according to the present invention and its manufacturing method are as follows: (1) Mg 0.4-1, Owt%, Si 0.8
-1.2 wt%, Cu 0005-0.40 wt%, and further contains Cr 0.05-0.40 wt%, Mn 0.05-0
．． 60wt%, Zr 0.05-0.20wt%, V
0102-0.15wt%, Ti 0.005-0.5
1%, B 0.0005 to 0.05wt%, and the balance is Al and inevitable impurities. (2) Mg0.4-1, Owt%, Si 0.8-1
．． 2wt%, Cu 0.05-0.40wt%, further Cr 0.05-0.40wt%, Mn 0.05-0
．． 60wt%, Zr 0.05-0.20wt%, V
0.02-0.15+ut%, Ti 0.005-0
．． An aluminum alloy ingot containing 0.0005 to 0.05 wt% of B and 0.0005 to 0.05 wt% of B, and the balance consisting of Al and unavoidable impurities is heated to 350 to 500 °C at a heating rate of 40'C/Hr or less before hot rolling. After heating to temperature 2-2
Hold for 4 hours or keep at a temperature of 350-450℃ for 2 hours.
After heating and holding for ~12 hours, further heating at 450~520°
A second invention provides a method for producing a high-strength AlMg-Si alloy, which is characterized by carrying out two-stage heating and holding at a temperature of C for 2 to 12 hours to reduce the crystal grain size to 50 μm or less.
It consists of two inventions.

The high-strength Al-Mg-Si alloy according to the present invention and its manufacturing method will be described in detail below.

First, the components and component ratios of the high-strength Al-Mg-Si alloy according to the present invention will be explained.

Mg is an element necessary to impart excellent mechanical properties, and if the content is less than 0.411 It%, sufficient strength cannot be obtained; If the content exceeds Owt%, the spinning processability of soft materials will be poor. Therefore, the Mg content is set to 0.4-i, Quit%.

Like Mg, Si is an element necessary to impart excellent mechanical properties, and if the content is less than 0.8 wt%, sufficient strength cannot be obtained, and if the content exceeds 1.2 wt%, Si is an element necessary to impart excellent mechanical properties. The toughness deteriorates. Therefore, the Si content is 0.8 to 1
, 2wt%.

Cu, like Mg and Si, is an element necessary to impart excellent mechanical properties, and if the content is less than 0.05 wt%, sufficient strength cannot be obtained, and if the content exceeds 0.40 wt%, If it is contained, the spinning processability of soft materials will deteriorate. Therefore, the Zr content is 0.05 to 0.40 wt%
shall be.

Cr, Mn, and ZrXV are elements that stabilize the structure,
Content is less than 0.05wt% Cr, 0.05w Mn
Less than t%, Zr less than 0.05wt%, V 0002w
If it is less than t%, this effect is small, the spinning workability is poor, and Cr is 0.40+++t%, Mn is 0.60+
ut%, Zr 0.20+ut%, V 0.15wt%
If the content exceeds each, the effect will be saturated and there is a possibility that giant compounds will be generated. Therefore, the Cr content is 0.05
-0.40wt%, Mn content is 0,05-0.60w
t%, Zr-containing Deca005-0.20+ut%, (2) content is 0.02 to 0.1.5 wt%.

Ti and B are elements that refine crystal grains, and the content is T
i Less than 00O05+ut%, B 0.0005t%
If the content is less than 0.0005 t% of Ti and 0.0005 wt% of B, the effect is saturated and there is a possibility that giant compounds may be generated.

Therefore, the Cr content is 0.005-0.5 wt%, and the B content is 0,00051%.

Next, a method for producing a high-strength AI Mg Si alloy according to the present invention will be explained.

The homogenization treatment of the ingot is less effective in preventing coarsening of crystal grains at temperatures lower than 350°C, and is no longer effective in preventing coarsening of crystal grains at temperatures higher than 500°C. Moreover, if the heating rate exceeds 40° C./Hr, the effect of preventing coarsening of crystal grains will be lost. And the retention time is 2
If it is less than 24 Hr, it is not sufficient to prevent coarsening of crystal grains, and if it exceeds 24 Hr, this effect may be saturated, and it is wasteful to hold it longer than that. Therefore, the homogenization treatment of the ingot before hot rolling is such that the ingot is heated to a temperature of 350 to 500°C at a heating rate of 40°C/Hr or less and then held for 2 to 24 hours.

In addition, when similarly performing two-stage heating, if the heating temperature in the first stage is less than 350°C and the heating temperature in the second stage is less than 450°C, the effect of preventing crystal grain coarsening will be small; The heating temperature of the first stage is 450℃, and the second stage heating temperature is 520℃.
If the temperature exceeds ℃, the effect of preventing crystal grain coarsening disappears, and if the holding time is less than 2 hours in both the first and second stages, the effect will be small, and if the holding time exceeds 12 hours, the effect of preventing crystal grain coarsening will disappear. I get saturated. Therefore, the two-stage heating is performed by heating and holding at a temperature of 350-4.50°C for 212 hours, and then heating and holding at a temperature of 450-520°C for 2-12 hours.
r.

[Example] Examples of the high-strength AlMg-Si alloy and its manufacturing method according to the present invention will be described.

Example An ingot (315 mm t) obtained by melting and casting an aluminum alloy having the ingredients and proportions shown in Table 1,
The performance of the material manufactured under the conditions described below was investigated.

(1) Conditions for the manufacturing method of the high-strength Al-Mg-Si alloy according to the present invention.

A: Heat the ingot to 450'C at a heating rate of 20°C/Hr.
After heating to a temperature of 1211r and holding it at 450~35
Hot rolling was performed at a temperature of 0° C. to obtain a 5 mmt plate material.

B: After heating and holding the ingot at a temperature of 400°C for 128r, heating and holding the ingot at a temperature of 500°C for 4hr, 450 to 35
Hot rolling was performed at a temperature of 0°C to obtain a plate material of 5 mmt.

(2) Similar condition C: The ingot was heated and held at a temperature of 520°C for 128r,
Hot rolling was carried out at a temperature of 450 to 350°C, and the thickness was 5mmt.
It was made into a plate material.

These plates were heated at 380°CX2Hr (cooling rate 20°C).
/Hr), and materials subjected to softening treatment at 500
℃×30m1n solution treatment and water quenching 170℃×8
The performance of T6 material was investigated after aging treatment.

The results are shown in Tables 2 and 3.

That is, the high-strength Al-Mg-Si alloy according to the present invention and the alloy of the present invention produced by the method for producing the same are different from the conventional alloy 6061.
Compared to soft materials that require spinning workability, the grain size is small, the strength increase in processed hard plates due to cold working is small, and the forming workability is significantly superior according to spinning tests using actual machines. .

In addition, the alloy of the present invention has significantly higher strength than the conventional alloy 6061 in the T6 material, which is required to have high strength and is subjected to solution treatment, quenching, and aging treatment after spinning.

Aging conditions for T6 material 535°C x 30 minutes → water quenching i-, 170°C x 8 hours 6 [Effects of the invention] As explained above, the high strength AlMg-6 according to the present invention
Since the i-series alloy and its manufacturing method have the above-mentioned structure, it is possible to reduce the Mg content and reduce the deformation resistance in soft materials compared to conventional alloys, improve spinning workability, and reduce the Mg content. By increasing the ratio of Si content to Si content, the mechanical properties after solution heat treatment, quenching and T6 aging treatment are significantly improved. Even when processed, there is no occurrence of surface roughness or cracking, and it has the excellent effect of significantly improving spinning processability.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a testing method for spinning moldability.

Claims (2)

[Claims] (1) Mg0.4-1.0wt%, Si0.8-1.2
wt%, Cu0.05-0.40wt%, and further contains Cr0.05-0.40wt%, Mn0.05-0.6
0wt%, Zr0.05-0.20wt%, V0.02
~0.15wt%, Ti0.005~0.5wt%, B
A high-strength Al-Mg-Si alloy containing one or more selected from 0.0005 to 0.05 wt%, with the remainder consisting of Al and inevitable impurities. (2) Mg0.4-1.0wt%, Si0.8-1.2
wt%, Cu0.05-0.40wt%, and further contains Cr0.05-0.40wt%, Mn0.05-0.6
0wt%, Zr0.05-0.20wt%, V0.02
~0.15wt%, Ti0.005~0.5wt%, B
An aluminum alloy ingot containing one or more selected from 0.0005 to 0.05 wt%, with the remainder being Al and unavoidable impurities, is heated at a heating rate of 40°C/Hr or less before hot rolling. After heating to a temperature of 350-500℃ at 2-
After holding for 24 hours or heating and holding at a temperature of 350 to 450 °C for 2 to 12 hours, further heat to 450 to 520 °C
A method for producing a high-strength Al-Mg-Si alloy, which comprises carrying out two-step heating and holding at a temperature of 2 to 12 hours at a temperature of 0.degree.