Experimental study on microstructure and mechanical properties of AA6061/Ti-6Al-4V joints made by bypass-current MIG welding-brazing

摘要

Microstructure and mechanical properties of Bypass-Current Metal Inert Gas (BC-MIG) welded AA6061/Ti6Al4V lap joint were studied. Due to the influence of bypass current, the heat input acting on base metal was reduced, the melting efficiency of filler wire was increased, and the metal transfer mode was changed from short circuiting transfer to projected transfer, which creates an improvement in wettability and spreading behavior of weld. Reliable Al/Ti joints were obtained by BC-MIG welding-brazing, and the tensile-shear strength of as received joint could reach a maximum of 190 M Pa, which was about 96% of AA6061 base metal. The metallurgical bonding between Al alloy and Ti alloy was a continuous reaction layer, and the intermetallic compounds (IMCs) consisted of TiAl3 and TiAl. The formation and growth of interface were discussed by melt flow.