Forming and tensile fracture characteristics of Ti-6Al-4V and T2 Cu vacuum electron beam welded joints

Dissimilar metals of Ti-6Al-4V and T2 Cu were successfully welded by vacuum electron beam. Forming and tensile fracture characteristics of the joints were studied in the paper. Wettability and tensile tests were introduced to reveal the weldability of Ti-Cu joints, meanwhile, OM, SEM, EDS, XRD and TEM were applied to assess the microstructure and fracture mechanism. The results shows that Cu can wet the surface of Ti alloy well, but not the opposite. Thus, shifting the electron beam on Cu sheet is helpful to improve appearance quality and bonding strength. Average tensile strength of Ti-Cu joints could reach 147 MPa, i.e. 63% of that of T2 Cu substrate when the electron beam was shifted to the copper side with an offset of 1.4 mm. The micro analysis demonstrate that there is a thin IMCs layer at the fusion zone. Which consists of a variety of Ti-Cu intermetallic compounds, e.g., Ti2Cu, TiCu, Ti3Cu4, βTiCu4, etc. Fracture morphologies indicate that it belongs to quasi-cleavage fracture and fracture occurred at the IMCs layer.