Optimum heat source position offset in welding of dissimilar Al-Cu metals using a theoretical approach

Abstract

Dissimilar metal joints find applications in power generation, automobile, petrochemical, nuclear and electronics industries. Many fusion and non-fusion welding techniques are utilized for joining dissimilar metals. However, welding of dissimilar metals present several challenges due to variation in thermal and physical properties. Formation of intermetallic compounds (IMCs) of base metals is one of the same. These intermetallics have detrimental effects on weld properties. One solution to minimize formation of these intermetallics is to shift heat source position with respect to weld interface; for example tool pin axis offset in friction stir welding and laser beam axis offset in laser beam welding. This heat source position is a major process variable in dissimilar metal welding. Decision of the heat source position offset is very important in dissimilar metal welding. Many studies have been reported investigating effects of the heat source position offset on mechanical properties of dissimilar joints where in experimental investigations have been carried out. However, a simple theoretical approach based on phase diagram is sufficient for the same. A theoretical approach to decide optimum heat source position offset is presented here and validated with published literature results for dissimilar Al to Cu welded joints.