JPS6158546B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an Al-Mg-Si alloy suitable for obtaining an extruded material suitable for use in construction materials, transportation equipment, daily necessities, and other materials that require good appearance and strength, and a method for producing the extruded material. . As aluminum alloys for extrusion molding, Japanese Industrial Standards already include industrial pure aluminum as well as aluminum alloys.
-Cu-based alloys, Al-Mn-based alloys, Al-Mg-Si-based alloys, Al-Zn-Mg-based alloys, etc. are specified. Among these, in Al-Mg-Si alloys, the hardenability tends to deteriorate as the amount of Mg ₂ Si increases.
For example, 6061 alloy requires almost no _T6 treatment to obtain sufficient strength. Furthermore, due to water cooling during quenching, significant distortion occurs in the extruded material, resulting in poor shape. Moreover, if the extrusion speed is increased during extrusion molding, the extruded surface tends to be baked and become rough, resulting in poor surface quality and loss of gloss, resulting in the extruded material becoming whitish. The present invention was made with the aim of improving the above-mentioned drawbacks of Al-Mg-Si alloys.
Less than 0.45%, Cr0.04~0.3%, B0.005~0.02%,
extrudability, characterized by containing 0.05-0.35% Fe;
It is an Al-Mg-Si alloy with good hardenability, and an aluminum alloy billet with such a composition is
Homogenization heat treatment is performed by heating at 450-600℃, and 400℃
This is a method for producing extruded materials characterized by extrusion processing at ~550°C. The most characteristic feature of the present invention is that by adding B, a sufficient extrusion speed can be guaranteed without damaging the surface quality of the extruded material, and the hardenability is also improved. without T ₆ treatment, i.e. T ₅
It is possible to obtain the necessary and sufficient strength through treatment alone. Such improvement is achieved by B along with Al.
This is because it forms an intermetallic compound called AlB ₂ , and this compound has a kind of cleaning effect (polishing effect) that removes deposits such as aluminum adhering to the die bearing surface. Further, B combines with Cr, which is an additive component, to alleviate and improve the hardenability deterioration effect of Cr. When B exceeds 0.02%, coarse intermetallic compounds of Al-B are formed and precipitate in the molten metal, and the effect of B addition is lost. When B is less than 0.005, it is difficult to obtain a bonding result with Cr. Both Mg and Si are effective in increasing the strength of products. If it is less than 0.35% Mg and 0.2% Si, the strength will be insufficient, and if it exceeds 1.5% Mg and 1.0% Si, the hardenability will decrease and sufficient strength will not be obtained unless water-cooled. Cu combines with Mg and is effective in increasing strength, but when it exceeds 0.45%, the extrusion pressure increases and
Extrudability decreases. Corrosion resistance also deteriorates. 0.11
If the amount is less than %, a sufficient addition effect cannot be obtained. Cr is effective in refining recrystallization and preventing grain boundary cracking in extruded materials, and also combines with B to produce the above-mentioned effects, but if it exceeds 0.3%, both extrudability and hardenability decrease. do. If it is less than 0.04%, sufficient addition effect cannot be obtained. Fe has the effect of refining the recrystallized grains of the extruded material. If it exceeds 0.35%, extrudability decreases (increase in pick-ups and surface defects) and hardenability decreases. If it is less than 0.05%, sufficient addition effect cannot be obtained. There is no problem if impurities are 0.05% or less for each component. In order to extrude a billet of the alloy composition of the present invention, it is first heated at 450 to 600°C to perform a homogenization treatment. A suitable heating time is 4 to 24 hours. As a result of this heating, the Al-Fe-Si eutectic compound aggregates into spherules and becomes a solid solution, while the Al-Cr-B compound precipitates uniformly in the matrix, and the interaction between the two causes extrudability. , hardenability is improved. When extrusion processing is performed at 400 to 550℃ after heating, a uniform and fine recrystallized structure is formed from the surface of the extruded material to a depth of about 0.1 mm, and the formation of this uniform recrystallized structure is prevents seizure with the die and improves the surface quality of the extruded material. If the above homogenization temperature is lower than 450℃, the diffusion rate of atoms will be slow and the effect will be insufficient.
If the temperature exceeds ℃, the ingot may partially melt, which is inappropriate. Furthermore, if the extrusion processing temperature is less than 400°C, the extrusion pressure will be high, and the processability will be insufficient due to solid solution of alloying elements during extrusion, resulting in a significant decrease in _T5 strength. If the temperature exceeds 550°C, the surface quality of the extruded material will deteriorate and processing heat will be added, which may cause grain boundaries to melt, which is not preferable. Next, examples and comparative examples will be described. First, the following three alloys were prepared as alloys. I
is an alloy of the present invention, and is a comparative alloy. () Al−0.85%Mg−0.65%Si−0.20%Fe−0.35
%Cu−0.1%Cr−0.015%B () Al−1.0%Mg−0.6%Si−0.20%Fe−0.2%
Cu−0.1%Cr () Al−0.85%Mg−0.65%Si−0.20%Fe−0.35
%Cu−0.1%Cr A billet consisting of the above alloy was heated to 520°C.
After homogenization for 8 hours, extrusion was carried out at 460°C. Water cooling material and extrusion speed 20 by die quenching during extrusion
One day after extruding the air-cooled material at ~50 m/min, the hardenability was compared based on the yield strength when tempered. The results are shown in Table 1, and the hardenability of the alloy was the best.

[Table] In addition, by changing the extrusion speed of each alloy without water cooling,
The surface quality after extrusion was compared. The surface quality was compared based on surface roughness (average roughness). The results are shown in Table 2, and the alloy was the best in terms of surface quality. The values in the upper middle row of Table 2 are the average roughness (μ
m).

[Table] As described above, according to the present invention, an aluminum alloy material with good extrudability and hardenability can be obtained, and by extrusion molding it, a product with a good surface quality can be obtained. , useful for manufacturing vehicle structural materials, etc.

Claims (1)

[Claims] 1 Mg0.35~1.5%, Si0.2~1.0%, Cu0.11~
0.45%, Cr0.04~0.3%, B0.005%~less than 0.02%,
extrudability, characterized by containing 0.05-0.35% Fe;
Al-Mg-Si alloy with good hardenability. 2 Mg0.35~1.5%, Si0.2~1.0%, Cu0.11~
0.45%, Cr0.04~0.3%, B0.005%~less than 0.02%,
An aluminum alloy billet containing 0.05 to 0.35% Fe is heated at 450 to 600°C to perform homogenization heat treatment,
A method for producing an extruded material from an Al-Mg-Si alloy with good extrudability and hardenability, characterized by extrusion processing at 400 to 550°C.