JPH02277741A - Aluminum alloy for cold forming - Google Patents

Abstract

PURPOSE:To obtain the Al alloy which is capable of cold forming, having good machinability without subjected to quenching and tempering treatment and having high strength and good corrosion resistance by specifying the contents of Cu, Mn, Mg and Cr. CONSTITUTION:An Al alloy contg., by weight, 0.05 to 0.3% Cu, 0.5 to 1.2% Mn, 0.6 to 1.6% Mg, 0.05 to 0.2% Cr and the balance Al with inevitable impurities is prepd. The alloy is suitable to cylindrical parts such as a receiver tank for a car cooler and an on-vehicle propane bomb, i.e., to be manufactured by cold forming such as cold forging and impacting.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an aluminum alloy for cold forming, and more particularly to cylindrical parts manufactured by cold forming such as cold forging and impact, for example. , relates to an aluminum alloy for cold forming, which is commonly used in receiver tanks for car coolers and propane cylinders for vehicles.

[Prior Art] Hereinafter, the conventional technology will be explained using a receiver tank as an example.

The receiver tank is a cylindrical pressure vessel that is installed in the refrigerant circuit of the car cooler and is filled with a certain amount of refrigerant.

In the past, receiver tanks were mainly made of iron, but recently there have been many receiver tanks made of A1 alloy, which has excellent light weight and corrosion resistance.

As the Al alloy, A6061 (Aj2-o, 4-0.
8%5i-0.15~0.40%Cu-0°8~1.2
%Mg-0.04~0.35%Cr) is used, and the extruded material or cast bar is hot cast or cold forged, then quenched and tempered, and the ends are welded. to make a cylindrical container.

However, with A6061, the desired strength and machinability cannot be obtained unless quenching and tempering are performed, resulting in a problem that the manufacturing cost is high.

Furthermore, considering that automobiles are used in areas with severe corrosive environments, a material with even better corrosion resistance than A6081 is desired.

[Problems to be Solved by the Invention] The present invention provides a cold-forming product that can be cold-formed, has good machinability without quenching or tempering, has high strength, and has good corrosion resistance. The purpose is to provide aluminum alloys.

[Means for Solving the Problems] The aluminum alloy for cold forming according to the present invention has Cu
: 0.05~0.3wt%, Mn: 0°5~1.2w
t%, Mg: 0.6-1.8wt%, Cr: 0.0
It is characterized by containing 5 to 0.2 wt% and the balance Aj2 and unavoidable impurities.It is excellent in cold forming, maintains strength and machinability without quenching or tempering, and has good corrosion resistance. .

"Effect" The role of each additive element and the reason for limiting the component ratio will be explained below.

Cu increases strength. Also, up to a certain amount of CU increases pitting corrosion resistance.

However, if the amount added is too large, cold formability and general corrosion resistance will deteriorate, and weldability will also deteriorate. That is,
Cub, less than 0.5 wt% is insufficient to maintain strength and pitting corrosion resistance. If it exceeds 0.3 wt%, cold forming becomes difficult, shell corrosion resistance is significantly reduced, and weld cracking is likely to occur. Therefore, it is set at 0.05 to 0.3 wt%.

Mn and Mg form a solid solution in the aluminum matrix and increase the strength. In particular, Mg increases the rate of work hardening caused by cold forming. That is, Mg and Mn increase strength and machinability through solid solution and work hardening.

0.5wt% ungrooved for Mn, 0.5wt% for Mg.
6 wt% ungrooved is insufficient to improve strength and machinability. Mn exceeds 1.2wt%, Mg exceeds 1.6wt%
If it exceeds, cold forming becomes impossible. Therefore, Mn is 0
．． 5 to 1.2 wt%, and Mg to 0.6 to 1.6 wt%.

Cr improves pitting corrosion resistance. If it is less than 0.05 wt%, there is no effect on improving pitting corrosion resistance, and if it exceeds 0.2 wt%, the effect on pitting corrosion resistance is saturated, and coarse compounds are produced, reducing cold formability. Therefore, the amount of Cr is set to 0.05 to 0.2 wt%.

In addition, in order to refine the crystal grains of the ingot, 0. 1wt%
Ti may be added in the following range.

[Example] An alloy having the components shown in Table 1 was melted by a conventional method, and a 200φ
An ingot was produced, and after a predetermined equalization heat treatment, it was hot extruded to form a 60φ round bar.

A 60φ round bar was cut into a predetermined length, and this material was cold forged to form a cylindrical member as shown in FIG. 1, and the occurrence of cracks during cold forging was examined.

A similar sample was also produced for A6061 (No. 11), but in the case of A6061, quenching and tempering were performed after cold forging.

Furthermore, the hardness of the head shown in FIG. 1 was examined and the strength was evaluated. In addition, drilling was performed and the machinability was evaluated based on the occurrence of cracks.

A CASS test and an acidic salt spray test were conducted under the following conditions with the shape shown in FIG. 1 to evaluate pitting corrosion resistance.

Acidic salt spray: 5% Na (, fL pH 3, 40°C CA
SS is SOO time Acid salt spray is 1600 hours On the other hand, a plate-shaped specimen is cut from the cylindrical part of the cylindrical member (see Figure 1), two of the plates are stacked, and the end is cut as shown in Figure 2. The welded parts were tanned and welded, the microstructure of the welded parts was observed, and weldability was evaluated based on the degree of microcracking.

The above evaluation results are shown in Table 2.

In addition, in Table 2, Cold forgeability: 0: No cracks Δ: Microscopic division ×: Large crack Machinability 2 burr level O: No Paris Δ: Minute Paris X: Large Paris outbreak Maximum pitting depth: Q: Less than 0.3mm Δ: 0. 3-0. 5mm X: 0.6mm or more are shown respectively.

As is clear from Table 2, the invention alloy (No.

1 to No. 5) are A3061 without quenching and tempering.
Strength and machinability equivalent to or higher than that of (No. 11) were obtained, and corrosion resistance was superior to that of A6061.

In addition, although the above-mentioned Example described the case where the sample was produced from an extruded rod, the same result was obtained when the sample was produced by forging a cast rod.

[Effects of the Invention] According to the present invention, there is provided an aluminum alloy for cold forming that can be cold formed, has good machinability without quenching or tempering, has high strength, and has good corrosion resistance. can be obtained.

Table 2

[Brief explanation of drawings]

FIG. 1 is a side sectional view showing the shape of the sample. FIG. 2 is a side view showing the welding method. Eight Main body Tanning is welding

Claims (1)

[Claims] Cu: 0.05 to 0.3 wt%, Mn: 0.5 to 1.2
wt%, Mg: 0.6 to 1.6 wt%, Cr: 0.05
An aluminum alloy for cold forming, characterized in that it contains 0.2 wt% of Al, and the remainder consists of Al and unavoidable impurities.