Microstructure and Mechanical Properties of Friction-Welded Alloy 718 and SNCRW Stainless Steel After Post-Weld Heat-Treatment

This study investigated dissimilar friction welding of Alloy 718 to SNCRW stainless steel. After friction welding, the effect of post-weld heat-treatment (PWHT) on the microstructure and mechanical properties was carefully studied. For this purpose, friction welded samples were annealed at 500, 720, and 900 °C for 8 hrs, respectively. Heat-treatment at 720 °C resulted in highest hardness due to the precipitation of g”. On the other hand, relatively low hardness was obtained when PWHT was not performed, or the heat-treatment temperature was not 720 °C. Residual stress in the welded joints was effectively reduced when heat treatment was performed at temperatures above 720 °C. Friction welded specimens fractured at the weld joint when no PWHT was performed or when PWHT was performed at 500 or 900 °C. On the other hand, when PWHT was performed at 720 °C, tensile failure occurred in the SNCRW base metal. Key words: Transient liquid phase bonding, Metailization, Interconnect, Power semiconductor, Intermetallic compounds, Lap-shear test