Resistance microwelding of SUS304 stainless steel fine wire

Abstract

Resistance microwelding of fine crossed stainless steel wires is of increasing industrial importance for medical devices. Therefore, a study has been performed to clarify the basic joining mechanisms. The effect of main process parameters such as welding current, force and weld time were investigated by detailed mechanical testing and metallurgical examinations. Especially, joint strength and microstructures were sensitive for welding current and force. It should be noted that no fusion nugget was formed at the weld interface. Since the joint breaking force was determined by bond area and interfacial strength in the case of interfacial fracture, both of them are needed to be optimized to obtain sound joint. Moreover, heat affected zone should be minimized. A bonding mechanism with several main process stages, wire collapse, surface melting, liquid phase squeeze out and solid-state bonding, was proposed. © 2007 The Japan Institute of Metals.