Investigation of mechanical, microstructural, and machining properties of AISI 420 martensitic stainless steel welded by laser welding

In this study, AISI 420 stainless steel sheets of 1.8 mm in thickness were joined by laser welding. To determine the mechanical and microstructural properties of these sheets, microhardness, tensile, optical microscope, and SEM and XRD examinations were made. The following results were obtained: the carbides dissolved in austenite near the weld metal of heat affected zone. The increase in laser pulse frequency was more effective in determining the penetration and width of the weld metal than current and focal diameter. The highest yield and tensile strength values were 269 and 857.34 MPa, respectively, at the welded sheet joined with no.7 parameter. The grain size and microstrain values of untempered welded sample were 229.322 nm and 0.00347, respectively, at the welded sheet joined with no.6 parameter. The narrowest kerf and the lowest microhardness were 161 μ and 293 HV, successively, and these were obtained in the weld metal of sample number 5.