Analysis of Laser-TIG Hybrid Welding Performance on 15-15Ti Stainless Steel Lock Bottom Structure

To investigate a kind of welding process of 15-15Ti stainless steel material for Sodium-cooled fast reactors, a method that can accommodate to the bottom lock structure while maintaining good welding performance after multiple welding cycles is explored. In this paper, laser-TIG hybrid welding process is adopted to a bottom lock structure made of domestically produced 15-15Ti stainless steel. The microstructural characteristics, microhardness, intergranular corrosion resistance, and mechanical properties of the weld seam were tested using metallurgical microscope, scanning electron microscope, hardness tester, and tensile testing machine. Comparisons were made between the weld morphology and properties after multiple welding cycles. The research shows that laser-TIG hybrid welding can realize the welding of lock bottom structure and obtain superior welding microstructure and mechanical properties. After multiple welding cycles, the weld seam solidification mode, microstructure, and mechanical properties remain unchanged, and the microstructure and mechanical properties of the weld have good consistency. This welding method of 15-15Ti material has broad engineering application potential and scenarios.