Investigation On Laser-TIG Hybrid Welding With Twin Wire Of Stainless Steels

For the welding of high performance,high purified materials,such as ultra low carbon stainless steel,titanium alloy and nickel alloy,high performance welds by using laser-TIG hybrid welding process with single welding wire can be obtained based on the low welding heat input and high welding speed.However,because of the low efficiency of single wire feeding,it is suitable for the welding of thin sheet,and the application of groove welding of thick plate is limited.To solve the above problems,a laser-TIG hybrid welding method with twin-wire for 8mm thick stainless steel plate was proposed.Effect of the welding parameters and wire space position on the appearance of welds was investigated.Welding process stability was evaluated through high speed camera,and the microstructures and the properties of welded joints were analyzed.The research showed that the laser-TIG hybrid welding process with twin-wire,of which laser was ahead of arc and the twin-wire was under laser,was stable and the weld shape was beautiful.Among numerous welding process parameters,light tungsten distance,laser power,defocus,wire feeding speed,welding speed and TIG current had great influence on the welding process stability and weld forming.For 8mm thick of 304 stainless steel welding,the welding parameters were as follows: light tungsten is 6~8mm,laser power is 3.5~6.0k W,the defocusing is +4~+8mm,the wire feeding speed is 3~10m/min,the welding speed is 0.5~1.2m/min,the welding current is 270~400A.By using recommended welding parameters,8mm thickness of Y groove stainless steel butt welding can be completed by two layers.The tensile strength of welded joint was the 93.7% of base material.Compared with the single wire feeding the welding deposition rate of laser-TIG hybrid welding method with twin-wire was increased by 100%.