JP4274170B2 - Aluminum alloy plate with excellent pulse laser weldability - Google Patents

Description

  The present invention relates to an aluminum alloy plate excellent in pulse laser weldability used for aircraft, vehicles, electrical and electronic equipment parts, and the like.

Aluminum is used for aircraft, vehicles, electrical and electronic equipment parts, etc. because of its light weight and good workability. On the other hand, laser welding is used for joining the parts because of its high accuracy and high speed. For example, battery cases used for power supplies such as display parts of electric and electronic equipment parts, motors, etc., after processing an aluminum alloy plate into a predetermined shape, battery members are incorporated, and finally the lid part is laser welded to the case Thus, a sealed battery is obtained. For such a sealed battery case, a JIS A3003 alloy (Al-Mn alloy) having a relatively high strength among aluminum alloy standards and a high-strength aluminum alloy with higher strength obtained by adding Mg to this are proposed. (Patent Document 1).
JP 2000-336448 A

  By the way, since aluminum has high thermal conductivity, continuous welding with a high calorific value is usually used in laser welding. However, when the thickness of the material to be welded is thin, pulse laser welding may be employed in which the amount of heat generation is low and the amount of heat input is easy to control.

FIG. 1 is a schematic diagram for explaining pulse laser welding, in which 1 is a plate to be joined on which a butt portion 2 is formed, 3 is a pulse laser beam, and the pulse laser beam 3 passes through a lens 4 to form a focal point 5; It reaches on the butting part 2 of the plate 1. The butted portion 2 is melted with the energy converged by the pulse laser beam 3, 6 is a welded portion, and h is a welding depth. The position of dissolution is changed by the relative movement of the plate 1 and the pulse laser device 8. As shown in the figure, the welded portion 6 continues and the plates 1 and 1 are joined by moving the melting position.

  When a high-strength aluminum alloy plate is welded by the pulse laser welding method, fine cracks 7 as shown in FIG. 3 are likely to occur in the welded portion. Therefore, heat input is performed so that the peak value of one cycle of the pulse waveform gradually decreases. It is carried out with measures such as controlling

  The inventors have discovered that if the total amount of certain elements of the high-strength aluminum alloy sheet is limited, fine cracks will not occur in the weld when welding by the pulse laser welding method without special measures. The present invention has been completed. That is, an object of the present invention is to provide an aluminum alloy plate that hardly cracks even when a high-strength aluminum alloy plate is welded by a pulse laser welding method and has good formability.

In the present invention according to claim 1, the alloy composition is Si: more than 0.20 to 0.60 mass%, Fe: 0.25 to 0.55 mass%, Cu: 0.10 to 0.35 mass%, Mn : 0.9 to 1.5 mass%, Mg: 0.25 to 0.65 mass%, Cr: 0.35 mass% or less, Zr: 0.25 mass% or less, Ti: 0.20 mass% or less and B: containing 0.02 wt% of one or more, and the balance Al and unavoidable impurities, among the alloy composition, Si, Fe, the sum of Cu and Mg is 1.3 wt% or less It is an aluminum alloy plate excellent in pulse laser weldability.

In the present invention according to claim 2, the alloy composition is Si: 0.25 to 0.60 mass%, Fe: 0.25 to 0.55 mass%, Cu: 0.10 to 0.35 mass%, Mn: 0.9 to 1.5 mass%, Mg: 0.25 to 0.65 mass%, Cr: 0.35 mass% or less, Zr: 0.25 mass% or less, Ti: 0.20 mass% or less, and B: containing 0.02 wt% of one or more, and the balance Al and unavoidable impurities, among the alloy composition, Si, Fe, the sum of Cu and Mg is 1. 3 wt% or less It is an aluminum alloy plate excellent in pulse laser weldability.

The present invention according to claim 3 is characterized in that the aluminum alloy plate excellent in pulse laser weldability according to claim 1 or 2 is subjected to a solution hardening treatment.

According to this invention concerning Claim 1 or 2, it can be set as a high intensity | strength aluminum alloy plate, and a fine crack does not generate | occur | produce in a welding part even if pulse laser welding is carried out. Since the aluminum alloy plate of the present invention is excellent in pulse laser weldability, it has the effect of being able to produce a reliable product that does not require cracking and can be joined without requiring any special device, and has a crystal of the plate. The grain can be refined to increase the formability of the plate and prevent rough skin of the product.

According to the third aspect of the present invention, when this aluminum alloy sheet is subjected to solution hardening and quenching treatment, it can be age-hardened by heating during use after forming, thereby preventing deformation or swelling of the product. effective.

  First, the composition in the present invention and the reasons for the limitation will be described. In the first invention, Si: more than 0.20 to 0.60 mass%, Fe: 0.25 to 0.55 mass%, Cu: 0.10 ˜0.35 mass%, Mn: 0.9 to 1.5 mass%, Mg: 0.25 to 0.65 mass%, and in the second invention, Si: 0.25 to 0.60 mass% Fe: 0.25-0.55 mass%, Cu: 0.10-0.35 mass%, Mn: 0.9-1.5 mass%, Mg: 0.25-0.65 mass%. . Si, Fe, Cu, and Mn are added for imparting strength, and if the amount is less than the lower limit, the effect is small. If the value exceeds the upper limit, the moldability is lowered. Particularly, when Si, Cu and Mg are subjected to a solution hardening treatment, they are age-hardened by heating during use after forming and have the effect of preventing product deformation and swelling.

Si, Fe, the sum of Cu and Mg is 1. A 3 mass% or less, to regulate Si, Fe, the sum of Cu and Mg is to prevent the occurrence divided by pulse laser welding. If the upper limit is exceeded, cracking occurs in pulse laser welding . When one or more of Cr: 0.35% by mass, Zr: 0.25% by mass, Ti: 0.20% by mass and B: 0.02% by mass are further contained in the composition, The crystal grains are refined to improve moldability and prevent the rough skin of the molded product.

  The inevitable impurities are out of control mixed from raw metal and return material, for example, 0.05 mass% or less of Cr, 0.05 mass% or less of Zr, 0.01 mass% or less of Ti, 0.0005% by mass or less and 0.15% by mass or less of Zn are inevitable impurities.

  Next, the production method of the plate will be described. Melting of the molten metal having the above-described composition is performed by a conventional method. The molten metal is cast by a semi-continuous casting method using a water-cooled mold to obtain an ingot. The obtained ingot is chamfered as necessary, and then homogenized by holding at a temperature of 550 ° C. or more for 2 hours or more in order to eliminate casting distortion. Sufficient homogenization effect cannot be obtained if the temperature is less than 550 ° C. and less than 2 hours. The homogenized ingot is then hot-rolled and then cold-rolled.

  After the cold rolling described above, a temperature of 500 ° C. or higher is allowed to pass for 1 minute or less, and then water quenching is performed for a solution quenching treatment. If the temperature is less than 500 ° C., a sufficient solution hardening effect cannot be obtained. Next, cold rolling is performed at a reduction rate of 10 to 55% for the purpose of tempering to obtain a plate of the present invention. If it is less than 10%, the elongation is high due to deep drawing and deep drawing cannot be performed. On the other hand, if it exceeds 55%, the ductility is low and cracks are likely to occur at the mold shoulder, which is not preferable.

  The plate obtained in this way is molded into various products. Among various containers, for example, when manufacturing a battery case having a plate thickness of 0.6 mm and a thickness of 5 × 25 × 50, The plate is subjected to drawing and ironing in more than a dozen steps to form a case, the rear cover assembled as a battery is put together, and the mating portion is pulsed laser welded.

  The case that has been pulse laser welded can be used without any special heat treatment, but it is age-hardened by subjecting it to a natural temperature rise during use or a heat treatment at a temperature of 40 to 170 ° C. after the welding. It can be strength and can be used in a stable state.

  Next, an example of pulse laser welding using the aluminum alloy plate according to the present invention will be described. For example, the plate and the plate are butt-fixed and welded in the atmosphere or, if necessary, using an inert gas such as argon as an assist gas. . The welding conditions are not uniform depending on the thickness of the plate, but welding is performed by appropriately changing the pulse time, output, defocusing distance, welding speed, and the like. When the thickness is about 0.5 to 2 mm, the time of one pulse is shortened to, for example, 0.3 to 5 ms, the output is lowered to, for example, 1.5 to 6 joules / pulse, and the defocusing distance is reduced. For example, a range of −5 to +10 mm and a welding speed of 0.8 to 1.5 m / min can be appropriately employed as a guide.

  A specific embodiment of the aluminum alloy plate according to the present invention will be described as follows.

  A molten aluminum alloy was melted, and a slab having a thickness of 530 mm was cast by a semi-continuous casting method. The composition of each slab is shown in Table 1 described later. Next, the slab was subjected to a homogenization treatment by holding at 590 ° C. for 5 hours after chamfering. After the homogenization treatment, hot rolling was started at the homogenization temperature, and a hot-rolled sheet having a thickness of 6 mm and an end temperature of 400 ° C was obtained. Next, a cold-rolled sheet having a thickness of 0.9 mm was obtained by 4 passes of cold rolling. Next, a cold-rolled sheet having a thickness of 0.9 mm was subjected to solution hardening corresponding to intermediate annealing in which water quenching was performed after holding the temperature at 520 ° C. for several seconds. After the solution hardening, it was further cold-rolled to obtain a rolled plate having a thickness of 0.6 mm.

Conditions for pulsed laser welding of the positions shown in FIG. 1 after butt-fixing the plates made in this way are as follows.
[Pulse laser welding]
Welding speed 1.2m / min 1 pulse time 0.5ms
Output Adjusted so that the welding depth is 0.3 mm Defocus distance Adjusted so that the welding width is 1 mm Frequency 100 Hz

  The welded portion thus welded was magnified 20 times and visually inspected to check for cracks. The results are shown in the following Table 2 together with the strength of a 0.6 mm thick rolled sheet. FIG. 2 is a sketch diagram of the weld location of test number 2 showing a typical weld location without cracks in the example of the present invention. FIG. 3 is a sketch diagram of a welded part of test number 11 showing a representative welded part in the comparative example, in which a welded crack 7 has occurred.

  In addition, when the plate made as described above is drawn and ironed and deep-drawn to form a bottomed container with a thickness of 5 mm, a width of 15 mm, and a height of 50 mm, the moldability and skin are good. Met.

  The plate of alloy code B, which has been hot rolled under the same conditions as in Example 1, is then cold-rolled to various plate thicknesses, solution-quenched under the same conditions as in Example 1, and then cooled. The plate was rolled to a thickness of 0.6 mm. This plate was deep drawn under the same conditions as in Example 1 to produce a bottomed container. Table 3 below describes the processing state of the formability.

  From the results in Table 3, it is understood that the deep drawing formability is excellent by setting the cold rolling rate after the solution treatment to an appropriate value.

It is the slope figure which showed the outline | summary of pulse laser welding. It is the slope figure which showed the aspect of the typical welding location without a crack by this invention. It is the same slope view as FIG. 2 which showed the aspect which the crack generate | occur | produced as a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plate 2 Butt part 3 Pulse laser beam 4 Lens 5 Focus 6 Weld part 7 Weld crack 8 Pulse laser device

Claims (3)

Alloy composition: Si: more than 0.20 to 0.60 mass%, Fe: 0.25 to 0.55 mass%, Cu: 0.10 to 0.35 mass%, Mn: 0.9 to 1.5 mass% %, Mg: 0.25 to 0.65% by mass , Cr: 0.35% by mass or less, Zr: 0.25% by mass or less, Ti: 0.20% by mass or less, and B: 0.02% by mass or less of containing and one or more, and the balance Al and unavoidable impurities, among the alloy composition, Si, Fe, pulsed laser sum of Cu and Mg is equal to or 1. 3 mass% or less Aluminum alloy plate with excellent weldability. Alloy composition is Si: 0.25-0.60 mass%, Fe: 0.25-0.55 mass%, Cu: 0.10-0.35 mass%, Mn: 0.9-1.5 mass% Mg: 0.25 to 0.65% by mass , Cr: 0.35% by mass or less, Zr: 0.25% by mass or less, Ti: 0.20% by mass or less, and B: 0.02% by mass or less. containing and one or more, and the balance Al and unavoidable impurities, among the alloy composition, Si, Fe, pulsed laser welding sum of Cu and Mg is equal to or 1. 3 mass% or less Aluminum alloy plate with excellent properties. 3. The aluminum alloy plate excellent in pulse laser weldability according to claim 1 or 2, which is subjected to a solution hardening treatment.

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