Stir friction welding method for dissimilar metal lap joint

Abstract

The invention provides a stir friction welding method for lap-joint welding of a first metal plate and a second metal plate. The hardness of the first metal plate is smaller than that of the second metal plate material, and a shaft shoulder and a stirring needle of a stirring head are pressed below the upper surface of the first metal plate and above the upper surface of the second metal plate. Pressure is applied to the stirring head, and the lower end face of the stirring needle is attached to and kept to the position above the upper surface of the second metal plate. Through stir friction welding, friction and heat generation are achieved on the surface of the upper-layer metal plate with the small hardness, the pressure is applied, an intermetallic compound is generated or diffusion happens or generation of the intermetallic compound and diffusion happen at the upper-lower junction face of the upper-layer plate and the lower-layer plate through control over the distance between thestirring needle and the upper surface of the lower-layer metal plate, and finally a dissimilar metal lap joint connector attractive in welding line forming and excellent in connector performance is obtained. The welding operation process is simple, and dissimilar metal lap-joint welding automation is easily achieved.

Description

technical field [0001] The invention relates to a friction stir welding method, in particular to a friction stir welding method for overlapping different metals. Background technique [0002] Friction stir welding, as a solid-phase joining technology, can effectively avoid excessive intermetallic compounds reducing joint performance in joining dissimilar aluminum alloys. At present, dissimilar metal lap joints are gradually being used in high-speed trains and automobile industries, especially aluminum-steel lap joints. Because, in the traditional friction stir welding, the material of the stirring head is generally made of tool steel. For the welding of dissimilar metal lap joints with a high hardness material, such as aluminum-steel lap joints, it is difficult to avoid serious wear and tear of the stirring pin. The fracture of the stirring pin, and a large number of intermetallic compounds will appear at the aluminum-steel joint surface, which will reduce the performance o...

AI Technical Summary

Problems solved by technology

[0004] The invention provides a friction stir welding method, in particular to a friction stir welding method for overlapping of dissimilar metals, which solves the problems of severe wear of the stirring needle, poor joint formation and low performance of the joint

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