PNNL

Abstract

Lightweighting of vehicles and portable structures is an important undertaking. Multi-material design is required to achieve conflicting design targets such as cost, stiffness, and weight. Friction stir welding (FSW) variants, such as friction stir dovetailing and friction stir scribe, are enabling technologies for joining of dissimilar metals. This work shows that FSW variants are capable of joining aluminum to steel. Characteristics of metallurgical bonding at the dissimilar material interface are strongly affected by weld temperature. Control of FSW process temperature enables metallurgical bonding with suppressed formation of intermetallics at the dissimilar material interface resulting in improved mechanical properties relative to competing techniques. Temperature control is a powerful tool for process development and to ensure weld quality of dissimilar material welds.