Investigations on the Microstructure and the Fracture Surface of Pulsed Nd: YAG Laser Welding of AISI 304 Stainless Steel

The paper presents pulsed Nd:YAG laser welding of the 304 stainless steels. The welding tests were carried out with various operational parameters. The effects of laser welding variables on the geometry, microstructure and solidification of the weld are considered. The austenitic or ferritic solidification is produced in the 304 austenitic stainless steel depended upon the cooling rate and its chemical compositions. The possiblity of austenitic solidification compared with the terrific solidification decreases with the chromium to nickel equivalent ratio and that increases with cooling rates. Moreover, more ferrite is obtained if the cooling rate is increased or the higher power laser is used. The surface of fracture samples was considered and the reason for failure was investigated. The study shows that the fracture is in ductile type.