Influence of pulse TIG welding thermal cycling on the microstructure and mechanical properties of explosively weld titanium/steel joint

The microstructures, interfacial compounds, and mechanical properties evolutions of the Ti/steel explosive welding interface during pulse tungsten inert gas (TIG) welding thermal cycling were studied. A Gleeble-1500D thermomechanical simulator was used to simulate the thermal cycling with the peak temperature (Tm) range of 692–1283 °C. The results show that the thickness of intermetallic compounds increased with the increase of Tm. When Tm is 1283 °C, the explosive welding interface was liquefied during the thermal cycling, which was consisted of α-Fe, α-Fe + Fe2Ti eutectic, Fe2Ti and a trace amount of α-Fe, FeTi, FeTi + β-Ti eutectic, β-Ti and a trace amount of FeTi, β-Ti + α-Ti and α-Ti from the steel side to Ti side. The substantial brittle phases (i.e., Fe2Ti and FeTi) can cause cracks in the interface and deteriorate the combination of the interface. In addition, the tensile and shear strength of the explosive welding interface decreased with the increased Tm. Reductions in strength were mainly attributed to the growth of the interfacial compounds.