Effect of protection condition on forming and performance of weld in titanium alloy laser-TIG hybrid welding

Laser-TIG hybrid experiments were carried out for butt weld of the TA15 titanium alloy sheets with 2.5 mm thick. Multifunction tensile testing machine, infrared thermometer, EPMA and SEM were used to analyze the weld joints, and a comparison with single TIG was made. Welding process, joint performance and weld protection were investigated. Results show that compared with single TIG welding, when full penetration welding of Ti alloy with 2.5 mm thick is realized, laser-TIG hybrid welding possesses faster welding speed and lower heat input, which leads to a narrower and a finer microstructure.Laser-TIG hybrid welding produces weld joints with higher strength, plasticity and better fatigue performance. And because the cooling rate of laser-TIG hybrid welding is higher than that of single TIG, it needs shorter time of protection to achieve good results.