Investigation of Hybrid Lap Welds of TI6AL4V and Stainless Steel with Bronze Interlayer

Welding of the austenitic stainless steel AISI 304 and Ti6Al4V is complicated by hard and brittle intermetallic compound formation. In this contribution, we study a laser welding method that partially overcomes this problem using interlayer. Bronze foil (CuSn6) of thickness 100 µm and 200 µm was inserted between steel and titanium sheets and lap welds were realized on pulsed Nd:YAG laser. Representative samples were investigated by nanohardness measurement, SEM/EDS, and XRD analysis to detect the localization of the intermetallic phases. The macrostructure of the weld cross sections was displayed by optical and digital microscopy. The nano-hardness test revealed the presence of very hard intermetallic mainly around the interface between the fusion zone and bottom metal sheet. EDS mapping displayed the main elements Fe, Cr, Cu and Ti distribution in the fusion zone, EDS line scanning detected elements‘ signals in the diagonal and horizontal directions. XRD analysis revealed expected intermetallic compounds FeTi and CuTi₂ and solid solution Cu_0.8Fe_0.2.