Diffusion Welding of Ti6Al4V and 17-4 Stainless Steel Using Cu/Ni Microlayers

In this report, diffusion welded joints (DWJs) between stainless steel (17-4 grade SS) and Ti6Al4V (T64) using transitional-bilayer (of nickel and copper) as intermediate material were synthesized with 3.5-MPa welding pressure at 775 degrees C for 15, 30, 45, 60, and 90 min. Region of interest was characterized using traditional microscopy techniques (scanning-electron and optical). Electron probe micro analyser was utilized to assess the interdiffusion activity of atoms across the welding interfaces. The bilayer regulated atomic mobility from SS to T64, and otherwise, when the welding was processed from 15 to 45 min; however, for the joints processed for 60 min and longer, the Ni/Cu bilayer was unable to obstruct the atomic movement from steel to Ti-alloy, and otherwise, which promoted layers of ternary reaction products along the SS side. The best strength of similar to 660 MPa (tensile) along with similar to 10% ductility was obtained for the dissimilar welding processed for 30 min. DWJs reached the maximum Charpy impact toughness of similar to 38 J when processed for 45 min.