Effect of heat input on microstructure and mechanical properties of Nd: YAG laser welded super duplex stainless steel-numerical and experimental approach.

This study reports the effect of different heat input (126 J/mm to 330 J/mm) on the microstructure and mechanical properties of pulsed Nd: YAG laser welded super duplex stainless steel UNS S32750 (SDSS) butt weld joints. Macrostructure exhibit incomplete, complete and complete penetration with a crater at the top of the weld bead, for low, middle and higher heat input respectively. Experimental macrostructure is in agreement with the numerical simulation performed by SYSWELD - a 3D software package. Maximum temperature is obtained at the mid section of the weld for all attempted heat inputs. Micro-analysis display an enhancement in the ferrite concentration in the weld zone for an increase in the heat input. Sigma phase, a reaction compound, is observed for the highest heat input. Higher micro-hardness is witnessed at the interface for the mid range heat input. The results of tensile test show that the tensile strength tends to reach a peak and then decrease with the increasing heat input. [ABSTRACT FROM AUTHOR]