Transient heat input model for friction stir welding using non-circular tool pin

Abstract

Frictional heat source in the contact surface of a rotating tool and a stationary work piece is used to join metal pieces along the weldline in the friction stir welding process. Temperature profile developed during welding decides the post weld properties on the joined work pieces not only along the weld line but also in the nearby layers of heat affected zone. As the heat input depends on the contact surface geometry in the tool/matrix interface, tool shape has a higher influence on peak temperature developed during the process and on the other hand it influences the post weld properties also. In this paper, a simplified analytical heat input model has been derived and validated for noncircular pin profile by introducing a new multiplication factor in the circular pin profile heat input model. Transient thermal numerical models are developed for, triangular, square and pentagonal pin profiles using analytical heat input results to analyse the change in temperature profiles with respect to the change in tool pin geometry. Furthermore, a detailed analysis is made to understand the percentage contribution of tool pin on the total heat supply.

Keywords

• friction sir welding
• non-circular tool pin
• heat input
• thermal analysis