Research On Laser-arc Hybrid Welding And Weld Bonding Of Titanium Alloy To Stainless Steel

Considering its inherent problems and limitations of fusion welding of titanium alloy to stainless steel, TC4 titanium alloy and 304 stainless steel are welded by laser-arc hybrid heat source firstly. The influence of welding process on welding formation was studied. Macrostructure and microstructure of cross sections, main compositions, mechanical property of welding joints with copper interlayer were examined. The fine quality joint was obtained, and welding process was optimized to improve the production efficiency.The tentative test found that titanium alloy and stainless steel could be connected by laser-arc hybrid welding successfully. The weld morphology is characteristic of beautiful scale pattern. However, a large number of brittle intermetallic compounds appear in the weld, which have negative effects on the properties of joint. The test parameter adjustment results that laser power, TIG current and welding speed affect the weld appearance mostly. Under the premise of obtaining effective welding joint, we found that:With the increase of laser power, the penetration increases, and the weld width has no obvious change. With TIG current increasing, the penetration and weld width both increase. With the increase of welding speed, the penetration decreases, and the weld width has no obvious change.In order to control the amount of brittle intermetallic compounds effectively, copper interlayer was added in the lap joint. The experimental results show that the maximum strength of joint is obtained when the laser power is 495 W approximately, and the tensile shear load is 3.33 kN·cm-1. The transition layer is characterized by Ti-Cu intermetallic compounds, solid solutions of copper and Fe-Cu eutectic mixture. With the increase of laser input, the thickness of Ti-Cu intermetallic compounds near the interface between titanium alloy and copper will increase, which makes harmful effect on mechanical property. Fracture of joint mainly happen at the interface between the titanium alloy and copper when laser input is higher. The mutual diffusion depth and density of elements such as copper and iron near the interface between copper and stainless steel will also increase, which is beneficial to enhance mechanical property. Fracture of joint mainly happens at the interface between the copper and stainless steel when laser input is lower. The key point of achieving good welding titanium and stainless steel joint is mainly demand on the controlling of Ti-Cu intermetallics and the Fe-Cu eutectic mixture thickness.The results found that adhesive combustion improved the energy of the copper-SS interface, and greatly promoted the diffusion of iron and even the melting of stainless steel when adding thimbleful of the adhesive. The interface bonding strength has increased to some extent. The maximum tensile shear load has reached 3.629kN·cm-1, which had a certain degree of improvement.