Characterization of microstructure and mechanical properties of dissimilar steel-copper joint made by FSW

چکیده مقاله

Welding of dissimilar metals by fusion welding processes is difficult and this normally results in some welding defects. Friction stir welding (FSW) as a solid state joining method can overcome the difficulties. In the current research, 304L stainless steel was joined to copper by FSW. Proper values of welding parameters, namely traverse speed, rotation speed and tilt angle, were obtained through response surface methodology (RSM). Eventually, regarding the optimum welding conditions, the effect of welding pass number on the microstructure and mechanical properties was investigated. The results indicated that suitable values of FSW process parameters obtained by application of RSM. The results also showed that grain size refinement during FSW, mainly affected the hardness of weld region. Additionally, it was found that the heat from FSW increased the grain size of heat affected zones (HAZ), especially of copper side. It was concluded that strength and ductility decreased as welding pass number increased. This was related to HAZ grain size enhancement as welding pass number increased.