Microstructure and Corrosion Properties of Laser-Welded SAF 2507 Super Duplex Stainless Steel Joints

摘要： SAF 2507 super duplex stainless steel has been welded using laser beam (LB) welding and laser/gas metal arc hybrid (LGH) welding processes. The pitting and intergranular corrosion properties of the welding joints have been tested using electrochemical testing and microstructure observations. The volume fraction of the ferrite phase reaches 70% in the weld zone of the LB welding joint, while the volume fraction of the ferrite phase is 60% for the welding joint of LGH due to the introduction of Ni from welding wire. The pitting corrosion resistance of the welding joint for LB is better than that of LGH. The pitting corrosion is easily conceived in the heat-affected zone (HAZ) because of the formation of Cr2N in the HAZ during welding.