Microstructure Evolution and Mechanical Properties of TA15/Ti60 Tailor Welded Blank by Electron Beam Welding

The effect of post-weld heat treatment temperature on the microstructure and mechanical properties of TA15/Ti60 tailor welded blank by electron beam welding was studied. The results show that the welded joint of as-welded TA15/Ti60 was reliable and the microstructure was mainly columnar crystal grains, which were arranged in a crisscross pattern and had a basketweave distribution. The hardness of as-welded joints was unevenly distributed where the base metal (BM) of Ti60 is higher than the BM-TA15 and fusion zone (FZ). After dual annealing, the hardness of the joint is higher than 750 to 850 degrees C and lower than that of 900 and 950 degrees C. Under the high-temperature tensile condition of 500 degrees C, the tensile strength and elongation of the TA15/Ti60 original welding specimens are 653.4 MPa and 12.8%, respectively. With the increase in the heat treatment temperature, the grains grew significantly in both the BM and the FZ, and the tensile strength was affected by the heat treatment temperature, causing the grains grow and the strength is different. At 900 degrees C, the microstructure of TA15/Ti60 welded samples has a uniform distribution, the tensile strength and plasticity were improved; while, the tensile strength was 680.2 MPa and the elongation reached the maximum 17.3%.