Characteristic Evaluation of Coaxial High-Frequency Induction Heating Hybrid Friction Stir Welding Process on High Strength Carbon Steel Sheets

Abstract

The thermo-mechanical properties of high strength steel limit the use of the friction stir welding(FSW) process in terms of quality and productivity. In this study, hybrid FSW(HFSW) using coaxial induction heating was designed to be applied to high strength steel and to ensure directional flexibility. The performance and characteristics of the HFSW process were evaluated on 590 and 980 dual phased high strength steel. The range of welding speeds adequate for the FSW and HFSW processes were compared, to evaluate the productivity of the HFSW process. During FSW, system deflection, vertical load and torque were measured to understand the process behavior. In HFSW, welding speeds were increased by 75% and 50%, respectively, for 590 DP and 980 DP steels compared to the conventional FSW processes. Furthermore, a relatively deeper heat-affected zone was achieved. The deeper heat-affected zone was produced by deeper tool plunging depth due to reduced system deflection. Earlier stabilization of the vertical load and torque is another feature of HFSW, due to the preheating effect. Employing the HFSW process, with its simple system configuration and process flexibility, can improve productivity and quality for welding high strength steels. Key words: Coaxial high-frequency induced heating, Friction stir welding, Dual phased high strength steel, Welding speed, Vertical load, Torque