Microstructure and Mechanical Properties of Ti-6.5Al-2Zr-1Mo-1V Alloy Fabricated by TIG Additive Connection

Abstract

Tungsten inert gas (TIG) technology can realize the fusion forming of large and complex components in aerospace, vehicle and other fields. In this study, a Ti-6.5Al-2Zr-1Mo-1V alloy base fabricated by hot isostatic pressing (HIP) was connected by TIG technology. Through in-depth analysis of the microstructure of the connected sample, the relationship between the microstructure and mechanical properties was established. In addition, the reasons for the difference in the mechanical properties between the connected and unconnected HIP samples were analyzed in detail. The results indicate that many basketweave structures are distributed inside the columnar grains epitaxially grown in the fusion zone (FZ). The microstructure of the heat affect zone (HAZ) includes equiaxed α, lath α, and massive fine secondary α phases. The microstructure of base metal (BM) is a typical bimodal structure. Compared with the HAZ and BM, the FZ has the highest microhardness of 410 ± 10 HV. The ultimate tensile strength (UTS) and yield strength (YS) of the connected samples are 1033.3 MPa and 970.7 MPa, respectively, which are greater than those of the HIP samples. The elongation (EL) of the connected sample is 8.0%, which is lower than that of the HIP samples. The fracture mode of both the connected and HIP samples was transgranular fracture.