Microstructure and High Temperature Tensile Properties of TC4/TC17 Electron Beam Welded Joints

Electron beam welding was carried out on TC4/TC17 dissimilar titanium alloy, and tensile tests were carried out at 400 degrees C. The results show that the microstructure of the heat affected zone (HAZ) and the weld are significantly different from that of the base metal. The microstructure of the HAZ on TC4 side is martensite, and the microstructure of the HAZ on TC17 side is metastable beta phase, and coarse columnar crystals are observed at the weld. Due to the dissimilar titanium alloy welding, the hardness of the heat affected zone on both sides presents different trends, and the hardness is the highest in the center of the weld. At 400 degrees C, the tensile strength and yield strength of welded joints are similar to those of TC4 base metal, but the elongation of welded joints is basically the same as that of TC17 base metal. There are few and shallow dimples with large size on the fracture surface of TC4/TC17 electron beam welding joint, which are oval in shape.