JPS62981B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to high strength aluminum alloys for extrusion. More specifically, the present invention relates to a high-strength aluminum alloy for extrusion that has improved extrusion processability when extruded sections are extruded at high speed. More specifically, the present invention relates to an aluminum alloy that can be used to produce aluminum profiles with improved mechanical properties by artificial aging during extrusion with press hardening. Conventionally, high-strength aluminum alloys for extrusion include:
Alloys made by adding small amounts of copper and chromium to aluminum-magnesium-silicon alloys, e.g.
JIS6061 alloy etc. are commonly used. However, these alloys have poor extrudability. For example, in the case of a solid material, an extrusion speed of about 25 m/mm must be adopted, and in the case of a hollow material, an even slower extrusion speed must be adopted, which poses a problem in terms of productivity. Further, it is difficult to manufacture a shape having a complicated cross-sectional shape, and the mechanical properties of the manufactured aluminum shape are not always sufficient. Therefore, the present inventors conducted intensive studies to find an alloy with improved extrusion workability and various properties of extruded shapes based on the JIS6061 alloy.As a result, the amount of magnesium was significantly reduced, and the amount of excess silicon in the alloy was By controlling the extrusion processability, the strength of the alloy is increased, and by adding appropriate amounts of copper and chromium or copper, chromium and manganese, the mechanical properties of the extruded shape are improved. They discovered this and arrived at the present invention. That is, the object of the present invention is to provide a high-strength aluminum alloy for extrusion that has improved extrusion processability and mechanical properties of the resulting extruded shape, and this object consists of 0.35 to 0.55% magnesium and 0.55% silicon.
~0.75%, iron 0.12%~0.19%, copper 0.20~0.40%,
This is easily achieved with extruded high-strength aluminum alloys consisting of 0.20-0.40% chromium, the balance aluminum and unavoidable impurities. In addition, the above purpose is
Magnesium 0.35-0.55%, Silicon 0.55-0.75
%, iron 0.12-0.19%, copper 0.20-0.40%, chromium and manganese in a total amount of 0.35-0.50%, the balance being aluminum and unavoidable impurities.
(In this specification, % represents weight percentage unless otherwise specified.) The present invention will be explained in detail below. The high strength aluminum alloy for extrusion of the present invention is 0.35
~0.55% magnesium, 0.55-0.75% silicon, 0.12-0.19% iron, 0.20-0.40% copper and
It contains 0.20-0.40% chromium or, instead of the above-mentioned chromium, it contains 0.35-0.50% chromium and manganese in total. If the amount of magnesium is less than 0.35%, the amount of magnesium silicide produced will be insufficient, and the specified strength will not be obtained. Moreover, if it exceeds 0.55%, the amount of magnesium silicide produced is too large, resulting in a decrease in extrusion processability and making high-speed extrusion difficult. A more preferable magnesium content is 0.40 to 0.50%. If the silicon content is less than 0.55%, the amount of excess silicon will be insufficient due to the relationship with the amount of magnesium silicide produced, and no improvement in strength can be expected by age hardening treatment after extrusion. Moreover, if it exceeds 0.75%, although the strength is satisfactory, extrusion processability deteriorates, and the intended purpose of the present invention cannot be achieved. A more preferable silicon content is 0.60 to 0.70%. The content of iron should be 0.12 to 0.19% in view of surface defects, anodizing properties, and strength of the extruded shape. A more preferable iron content is 0.13-0.16%. The content of copper and chromium is 0.20~0.40% for copper and 0.20~0.20% for chromium in terms of extrusion workability and shape strength.
It needs to be 0.40%. More preferred content is 0.31-0.40% for copper and for chromium
It is 0.25-0.35%. Chromium can be partially replaced with manganese, but in that case, the total amount of chromium and manganese added should be 0.35 to 0.35 from the viewpoint of shape strength.
It needs to be 0.50%. In addition, when the amount of other unavoidable impurities increases, the surface condition of the extruded shape often deteriorates.
It is preferable that each content is 0.05% or less, and the total content is 0.15% or less. Note that this alloy can be subjected to refinement treatment using a master alloy or solvent containing titanium and/or boron at the stage of melting in the same way as ordinary JIS6061 alloys. The aluminum alloy of the present invention is usually formed into a billet by semi-continuous or continuous casting for use in extrusion processing. The aluminum alloy billet of the present invention is homogenized prior to extrusion as in the usual case, but the conditions are about 480-580°C for 2-15 hours. The homogenized billet is generally cooled, then preheated to a suitable extrusion temperature, and extruded. The preheating temperature during extrusion processing is usually 450℃ for solid materials.
-500℃, hollow material is about 470-520℃, extrusion speed is 20m/mm or more for hollow material, 35m/mm for solid material.
m/mm or more. The obtained extruded profile is usually reheated to 515-550°C and then subjected to T4 treatment by water quenching, or alternatively, after quenching the obtained extruded profile, it is heated at 160-180°C for 5-12 By applying T6 treatment by time aging treatment, the mechanical strength of the shape material is improved. It is also effective to subject extruded sections obtained from the alloy of the present invention to T4 or T6 treatment as described above, but after T5 treatment, for example, press quenching with fan cooling (cooling rate of 10°C/sec or less). ,
The mechanical strength of the profile can also be improved by performing T5 treatment by aging at 160-180°C for 5-12 hours. In this case, sufficient mechanical strength comparable to the T6 standard of JIS6061 alloy can be obtained only by T5 treatment. The shape thus obtained can be made into a final product as it is or by being subjected to molding, anodizing, and painting if necessary. As explained in detail above, the alloy of the present invention has good high-speed extrusion processability, and therefore has better productivity than the use of ordinary 6061 alloy. In addition, the extruded shape using the alloy of the present invention has excellent mechanical properties, and by simply applying T5 treatment to the extruded shape, it can be compared to JIS6061 alloy.
Mechanical strength comparable to T6 standard can be obtained. EXAMPLES Next, the present invention will be explained in detail using examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof. Example 1 Regarding an aluminum alloy billet (outer diameter 153 mm, length 500 mm) having the composition shown in Table 1, 530
Homogenization was carried out at ~580°C for 2-6 hours. Thereafter, a solid material having a thickness of 2 mm and a width of 18 mm was extruded under the conditions shown in Table 1 to obtain an extruded shape sample. The maximum extrusion pressure and extrusion speed are shown in Table 1.

[Table] Next, test sample 1, sample 3, and sample 4 under the following conditions.
T5 treatment or T6 treatment was performed. Table 2 shows the mechanical properties of each treated material. T5 treatment: The obtained extruded shape is air-cooled with a fan and then aged at 175°C for 6 hours. T6 treatment: The obtained extruded profile was heated at 525℃ for 25 minutes, then water quenched, and then heated to 175℃ for 6 minutes.
Time, aging process.

[Table] From the results in Tables 1 and 2, it is clear that the aluminum alloy of the present invention has better extrusion workability than the JIS6061 alloy, and the obtained shapes have excellent mechanical properties.

Claims (1)

[Claims] 1. Magnesium 0.35-0.55%, silicon 0.55-0.55%
A high-strength aluminum alloy for extrusion consisting of 0.75% iron, 0.12-0.19% iron, 0.20%-0.40% copper, 0.20-0.40% chromium, and the balance aluminum and unavoidable impurities. 2. In the high-strength aluminum alloy for extrusion according to claim 1, the copper content is 0.31 to 0.40.
% alloy. 3 Magnesium 0.35~0.55%, Silicon 0.55~
A high-strength aluminum alloy for extrusion consisting of 0.75% iron, 0.12-0.19% iron, 0.20-0.40% copper, a total of 0.35-0.50% chromium and manganese, and the balance aluminum and unavoidable impurities. 4. In the high-strength aluminum alloy for extrusion according to claim 3, the copper content is 0.31 to 0.40.
% alloy.