JPH0441647A - Aluminum alloy for forming excellent in zinc phosphate treatability and baking hardenability - Google Patents

Abstract

PURPOSE:To obtain an Al alloy for forming excellent in zinc phosphate treatability and baking hardenability by adding specific elements to Al. CONSTITUTION:An alloy which has a composition consisting of, by weight, 0.5-1.4% Si, 0.4-1.0% Mg, 0.01-0.20% Ni, and the balance Al with inevitable impurities or further containing one or more kinds among 0.01-0.60% Mn, 0.01-0.30% Cr, 0.01-0.25% Zr, and 0.04-0.50% Cu is cast, homogenized, hot-rolled, and cold-rolled into a sheet of 1mm thickness. Further, this sheet is subjected to solution treatment in a continuous annealing furnace at 540 deg.C for 1min and successively to forced air cooling, followed by room temp. ageing for one month. By this method, the Al alloy excellent in baking hardenability as well as in zinc phosphate treatability can be obtained.

Description

[Detailed Description of the Invention] [Industrial Fields of Application] The present invention provides a zinc phosphate treatment process that is particularly suitable for manufacturing transportation equipment such as automobile body sheet materials, and has excellent bake hardenability. Regarding aluminum alloys for forming processing.

[Prior Art] Conventionally, AA601B (AI-1,0~
1.5%Si-0.25~0.6%Mg 0.20
56 or less Cu -0, 20% or less Mn) AA611
．． 1 (A 10.7~11%S i-0,50~1,
0%M g -0,50~0.9%Cu -0,1O~
0.45%M n ) is known, and A I -0.4~1.2%S i -0.4~ with Fe as an essential component.
1.1%Mg-0.1~0.6%CuO,05~0.3
5%Fe-0.2~0.8%Mn alloy (Special Publication No. 59
-39499) and A with improved spot welding properties.
l-0,3~1.5%5i-0,4~1.5M g-
0.03% or less Cu-0.1% or less Mn (U.S. Patent No. 4
No. 460,418) has also been developed.

[Problems to be Solved by the Invention] However, when a zinc phosphate film is formed as a pre-painting treatment in the above conventional processing of aluminum alloy materials and automobile panels, there is a problem that a uniform film cannot be obtained. Yes, paintability is poor. Therefore, in the present invention, Ni
This problem is solved by adding .

[Means for Solving the Problems] The present invention provides Si: 0.5 to 1.4%, Mg:
0.4-1.0%, Ni: [1,01-0,20
%, or further M n : 0.01
~0.60%, CT: 0.01~0.10%, Z
r: 0.01~0.25%, Cu: 0.04~
It is an aluminum alloy for molding that has good zinc phosphate processability and excellent bake hardenability, and is characterized by containing one or more of 0.50% and the remainder consisting of Al and unavoidable impurities.

The reasons for limiting the above composition are as follows.

Si: Necessary to obtain high strength; if it is less than 0.5%, the desired strength cannot be obtained, and if it exceeds 1.4%, grain boundary precipitation will occur, ductility will decrease, and corrosion resistance will also deteriorate. .

Mg: Necessary to obtain high strength together with Si; if it is less than 0.4%, the desired strength cannot be obtained;
%, grain boundary precipitation occurs frequently.1. Ductility decreases, and corrosion resistance also deteriorates.

Ni: Promote cathode reaction by adding a small amount,
Forms a uniform fine zinc phosphate film. The amount is 0.0
If it is less than 1%, there is no effect, and if it exceeds 0.20%, intermetallic compounds are formed and formability deteriorates.

Mn, Or, Zr: Effective for creating a uniform crystal grain structure and obtaining bake hardenability. If the amount of each is less than 0.01%, the desired effect cannot be obtained, and if the amount exceeds the upper limit of each, coarse intermetallic compounds are formed and mold cracks are likely to occur.

By adding Cu:Ni in combination, the cathode reaction during formation of the zinc phosphate film is further promoted, a uniform fine film can be stably formed, and it is also useful for improving strength.

If it is less than 0.04%, this effect will be small, and if it exceeds 0.50%, corrosion resistance will be poor and moldability will be reduced.

[Example] After casting the alloys shown in Table 1, homogenization treatment, hot rolling,
After cold rolling, it was made into a plate with a thickness of 1IIv. Further, the sample material was subjected to solution treatment at 540° C. for 1 minute in a continuous annealing furnace, followed by forced air cooling and aging at room temperature for one month.

Table 2 shows the evaluation results of the sample materials. Zinc phosphate film is
SEM was used to examine whether the film was uniformly coated over the entire surface.

Although good performance was obtained in Examples 1 to 5, the moldability of Comparative Example 1 decreased due to the large amount of Ni. Comparative example 2 is N
Since the amount of i is small, uniform surface treatment cannot be performed, resulting in poor coating uniformity. Since Comparative Example 3 has a large amount of Mn and Zr,
Many intermetallic compounds are formed, resulting in poor formability.

Table 1 Chemical composition (vt%) Table 2 Ev, Erichsen value C Effects of the invention As explained above, the aluminum alloy of the present invention has good zinc phosphate treatment properties and excellent bake hardenability. This material is useful as a material for transportation equipment, including automobile body sheet materials.

Patent applicant: Sumitomo Light Metal Industries, Ltd. Agent Patent Attorney Hidetake Komatsu Agent Patent Attorney Hiroshi Asahi

Claims (2)

[Claims] (1) In weight%, Si: 0.5-1.4%, Mg: 0.
Contains 4 to 1.0%, Ni: 0.01 to 0.20%,
An aluminum alloy for molding which has good zinc phosphate treatment properties and excellent bake hardenability, the remainder being composed of Al and unavoidable impurities. (2) In weight%, Si: 0.5 to 1.4%, Mg: 0.
4 to 1.0%, Ni: 0.01 to 0.20%, and further M
n: 0.01-0.60%, Cr: 0.01-0.30
%, Zr: 0.01-0.25%, Cu: 0.04-0
．． An aluminum alloy for molding which has good processability to zinc phosphate and excellent bake hardenability, characterized by containing at least 50% of zinc phosphate, and the remainder consisting of Al and unavoidable impurities.