Effect of different welding procedures on microstructure and mechanical property of TA15 titanium alloy joint

Abstract

Abstract TA15 titanium alloy is welded by electron beam welding (EBW) and pulsed Nd:YAG laser beam welding (P-LBW), respectively. Results show that the fusion zone (FZ) is mainly composed of acicular α′ martensite, while the acicular α′ martensite in the FZ of EBW joint is coarser. The quantity of martensite in the FZ of EBW joint is larger and the distribution of martensite is denser. The microstructure of heat-affected zone (HAZ) of the two joints is similar. The HAZ near FZ consists of primary α phase and acicular α′ martensite, and the HAZ near base metal (BM) consists of primary α phase, secondary α phase, and β phase. The hardness in the FZ of EBW joint is slightly higher than that of the P-LBW joint. The tensile strength of both joints is close to that of the BM, but their elongations are decreased to a certain extent. The tensile performance of the EBW joint is slightly better than that of the P-LBW joint. Both joints fail in the BM during stretching. There are many dimples on the fracture surfaces, and the two joints obviously present the characteristics of ductile fracture.