Microstructure and properties of GH3128 alloy laser welding joint

The butt welding of GH3128 alloy with a thickness of 3 mm was carried out by laser welding, and the influence of welding process parameters on the weld formation was studied. At the same time, the microstructure of the weld and the mechanical properties of the joint were compared and analyzed with those of TIG welding. The results show that a well welding formation can be obtained under the welding process parameters of laser power 4 kW, welding speed 1.5 m/min and defocusing amount + 3 mm. The microstructure of the weld zone of laser welding and TIG welding is composed of austenite γ' + brittle carbides. Compared with TIG welding, the microstructure grain of laser welding weld zone is fine, and the carbide size distributed between dendrites and grain boundaries is smaller. The tensile strength of laser welding joint is 12% lower at room temperature and similar at high temperature. Low cycle fatigue at room temperature is 4.5 times higher. Laser welding joint has low tensile strength at room temperature and high low cycle fatigue performance, which is mainly affected by element burning loss and carbide size during welding.