Mechanism of thermo-mechanical uniformity enhancement in dissimilar metal rotary friction welding via end-face geometry optimization

Abstract

The inherent radial non-uniformity of thermo-mechanical distribution in conventional rotary friction welding (RFW) of bar joints leads to heterogeneous microstructures and compromised mechanical properties. A tapered end-face design can actively regulate the thermo-mechanical coupling process, addressing the critical challenge of joint performance inconsistency. This study develops a three-dimensional thermal-mechanical coupled finite element model to elucidate the influencing mechanism of end-face design on the Al alloy/steel RFW process. The model accurately predicts interface temperature evolution and joint deformation, enabling quantitative analysis of spatial variations in thermo-mechanical fields. Results reveal that tapering the Al alloy end-face elevates the interface temperature at the center region by promoting plastic deformation under high contact pressure while restricting excessive material outflow. Furthermore, a tapering steel end-face with a small platform is identified as optimal for improving temperature uniformity and removing initial interface material. This work establishes a mechanistic link between end-face geometry, heat generation, and material flow, thereby providing a design-oriented framework for achieving homogeneous joints in dissimilar-metal RFW.