In this paper, the microstructure evolution and mechanical properties of electron beam welded joints of 30 mm thick TC4 titanium alloy were systematically studied. The results show that the central part of the fusion zone is composed of coarse primary β columnar crystals, the interior is a mixed structure composed of grain boundary α phase, massive α cluster and part of the basket structure, and the fusion zone near the heat-affected zone is composed of equiaxed primary β grains. There is significant microstructure inhomogeneity in the heat-affected zone. As the distance from the fusion zone increases, the content of β-transition microstructure (secondary α-sheet + residual β-phase) gradually decreases, while the content of primary α-phase gradually increases. The average microhardness of the fusion zone is ~50 HV higher than that of the base metal, the tensile strength of the joint reaches 906 MPa, and the joint strength coefficient reaches 96%. The tensile fracture position is located in the fusion zone.
TC4 titanium alloythick plate electron beam weldingmicrostructuremechanical properties
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