Laser Surface Reinforcement of the Ti/Al TIG welded Joint

The microstructure of the Ti/Al weld seam (WS) was uniform, and a good metallurgy bond between TC4/5052 aluminum alloy substrates was obtained without obvious defects after the Tungsten inert gas (TIG) process. Then, a remelt layer (RL) with fine microstructure can be formed by means of a laser remelting (LR) technique of the Ti/Al TIG joints. The Ti–Al intermetallics were produced adhered to the weld joints’ surface, exhibiting the extreme high surface hardness. The micro-hardness distribution of this RL surface was in a range of 1150–1200 HV0.2, which was significantly higher than that of the TC4 titanium alloy substrate. The high micro-hardness of the weld joints’ surface can be mainly ascribed to the actions of the Ti–Al intermetallics, the fine grain and the solid solution strengthening.