A study of the critical viscosity model of friction stir welding in relation to tool features

Abstract

Modeling Friction Stir Welding (FSW) has proven elusive over the past two decades since being patented by The Welding Institute in 1991. One promising model developed by Nandan et al. explains material flow through a critical viscosity. Material flow using a critical viscosity model is developed and examines how tool features affect viscosity and material flow. Four different tools with different features were used to conduct experimental welds to determine the roles of shoulder scrolls, pin threads, and the shape of the pin. In-process forces were measured, and specimen were tensile tested to analyze the impact of tool features. Finally, a new method to compare welding parameters across different tools and machines is developed and optimal parameters are discussed.