Microstructure and Corrosion Properties of Laser-Welded SAF 2507 Super Duplex Stainless Steel Joints
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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.
Keywordsintergranular corrosion laser beam welding laser-GMAW hybrid welding pitting corrosion super duplex stainless steel
The authors acknowledge the financial support provided by the National Natural Science Foundation of China (Grant Nos. 51775254 and 51405206) and the China Postdoctoral Science Foundation (Grant No. 2017M611750).
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