Detailed Investigation of the Effects of Processes Parameters on the Joint Properties of Laser Welded Ferritic Stainless Steel

In this study 1.2 mm thick 441 ferritic stainless steel sheets were sub-jected to Nd:YAG laser welding to investigate the impacts of the laser power, P, welding speed, v, and defocusing amount, increment f, on the perfor-mance of the welded joints. The results revealed that P=2.0 kW, v=1.8 m/ min and increment f=+2 mm were the optimal welding parameters. The weld seam featured a ferrite organization, with trace Fe-Ti compounds and fine iso-metric crystals at the center of the weld bead. The laser welded joint fea-tured a uniform grain size, which contributed toward the tensile strength and elongation of the joint. Notably, specimen fracture, namely a typical ductile fracture, occurred at the parent metal when subjected to tension. The Ti-C compounds and Fe-Ti compounds in the weld were found to inhibit dislocation movements and grain growth behaviours, which, in turn, improved the hardness of the welded joint.