Effect of process parameters in microstructural and mechanical properties of Nd: YAG laser welded super duplex stainless steel

Abstract

Abstract This present study reports the influence of diverse heat input (laser power/welding speed) on the weld zone macrostructure, microstructure, micro-hardness and tensile strength of super duplex stainless steel (SDSS), butt welded by a pulsed 600 W Nd: YAG laser welding machine. The diverse heat input is implemented by altering the process parameters viz., welding speed (100–250 mm/min), laser power (500–550 W), focal position (−1 to +1 mm) and pulse frequency (10–20 Hz). Macrostructure exhibit complete penetration for a lower heat input, while formation of crater is observed, for the experimental conditions having higher heat input. Epitaxial grain growth is observed at the weld zone, and the ferrite concentration increases with the heat input. Higher micro-hardness is obtained at the weld interface, for all attempted conditions. The maximum tensile and yield strengths are obtained for the experimental condition having lower heat input. The increase in strength is attributed by the ductile mode of fracture.