Comparative Study on Microstructure and Aluminum Distribution Between Laser Beam Welding and Electron Beam Welding of Ti-6Al-4V Alloy Plates

Ti-6Al-4V alloy plates with a thickness of 4 mm were joined by electron beam welding (EBW) and laser beam welding (LBW). The comparison of LBW and EBW was performed according to grain morphology, microstructure, aluminum distribution, and microhardness of the joints. Results indicate that compared with LBW joint, more equiaxed grains are observed around the central zone of the EBW joint. The microstructure in fusion zone (FZ) of EBW joint presents more uneven with obviously coarser acicular martensite alpha '. Moreover, the aluminum element content of EBW joint is substantially lower, which demonstrates a more significant burning loss behavior in EBW process. The lower aluminum content in the upper center areas of the joints is attributed to the more significant element burning loss caused by higher temperature, whereas more uniform aluminum distribution in the upper part of the joints is ascribed to stronger convection form within the upper part of the joint. In addition, the characteristics of convection and thermal field within the molten pool are recognized as vital factors influencing the aluminum distribution. The lower microhardness profile in FZ of the EBW joint is principally attributed to coarser acicular martensite alpha ' and lower aluminum element in EBW joint. Graphic

Automated summary

Ti-6Al-4V alloy plates with a thickness of 4 mm were joined by electron beam welding (EBW) and laser beam welding (LBW). Comparisons of LBW and EBW joints were made based on grain morphology, microstructure, aluminum distribution, and microhardness. Results showed that EBW joints had more equiaxed grains, uneven microstructure, coarser acicular martensite alpha ', and significantly lower aluminum content compared to LBW joints. The differences were attributed to higher temperature causing more burning loss behavior of aluminum elements in EBW process.