Study on spatter reduction of resistance spot welding of SPRC440 using hemispherically concaved electrode

Abstract

Resistance spot welding is one of the most popular welding processes used to join sheet metals. Weld quality sometimes decreases due to spatter. In this paper, a hemispherically concaved electrode, which has a hole on the end of it, is proposed to reduce spatter. To verify the weldability using spot welding with the hemispherically concaved electrode, tensile shear strength and cross-tensile strength were measured by a universal test machine. In addition, the cross-sectional area of the weld was observed by optical and electron microscopy to analyse defects. As a result, in the case of using the hemispherically concaved electrode, spatter was remarkably reduced. Spatter reduction is caused by the inflow of molten metal into the hole of the hemispherically concaved electrode. Furthermore, the allowable region in lobe curve became larger. Therefore, this hemispherically concaved electrode is useful for spatterless welding without the reduction of strength.