Dissimilar joining of TC4 alloy to ST16 steel by GTAW

The feasibility of direct fusion welding of TC4 alloy to ST16 steel by GTAW using CuSi3 filler wire was investigated. Defect-free fusion welded joints were obtained. Various intermetallic compounds, such as Ti2Cu, TiCu, AlCu2Ti, TiCu2 and Ti5Si3 phases, orderly formed in Ti/weld transition zone. Ti and Si diffused into ST16 steel, and an interface formed between copper weld and ST16 steel substrate. The resultant joints fractured at the ST16 steel substrate, and the tensile strength reached 282 MPa. The formation of various TixCuy IMCs and the solution strengthening induced by diffusion of Ti and Si led to the increase of microhardness in Ti/weld transition zone and copper/steel interface, respectively.