Effect of active gas on weld appearance and performance in laser-TIG hybrid welded titanium alloy

The influence of shielding gas compositions with different CO2 contents on the weld appearance and performance were studied in laser-tungsten inert gas (TIG) hybrid welding process. The research results presented that the shielding gas composition made significant effect on the weld formation during laser-TIG hybrid welding process. Smooth transition of weld reinforcement can be obtained when CO2 content in the arc shielding gas is over 2%. Meanwhile, in pure Ar shielding condition, behind the laser action point, the liquid metal flowed outward, while it is inward if the shielding gas contained greater or equal to 2% CO2. This phenomenon can be mainly determined by Marangoni flow. In addition, results of tensile tests showed that the tensile strength of the weld joint with 2% CO2 is 1057 MPa, as 94.4% of the base metal.