Effect of laser mode on microstructure and corrosion resistance of 316L stainless steel weld joint

The different welding methods can produce weld joints with different microstructure, mechanical properties and corrosion resistance. The purpose of this paper is to investigate differences of two kinds of weld joints that prepared by the Nd:YAG and the Slab CO2 lasers welding 316L stainless steel. The macroscopic, microscopic structure and corrosion resistance of the weld joints are characterized by optical microscope, scanning electron microscope (SEM) and electrochemical workstation. The results show that compare with the weld joint of the Slab CO2 laser, the Nd:YAG laser with the larger dimension of weld metal zone and heat affected zone, and the dendrite arm spacing (DAS) and secondary dendritic arm spacing (SDAS) are larger on both sides of the weld metal under the heat input is the same. More ferrite and carbide precipitate in the heat affected zone of the Nd:YAG laser, which contributes to the corrosion resistance of the entire welded joint is worse. The grain size in the center of the Slab CO2 laser weld metal is coarser results in the corrosion resistance of its weld metal inferior to the Nd:YAG laser.