Effect of optimal weld parameters in the microstructure and mechanical properties of autogeneous gas tungsten arc weldments of super-duplex stainless steel UNS S32750

The present study reported the optimization of process parameters such as current and welding speed to achieve maximum penetration in the bead on plate Gas Tungsten Arc Welding (GTAW) of super-duplex stainless steel thick plates by autogeneous-automatic mode. Two factor three level Taguchi L9 orthogonal array was employed to determine the maximum penetration. A maximum penetration of 3.4439 mm with a heat input of 1.17 kJ/mm was obtained on employing a current of 250 A and a welding speed of 150 mm/min. Experimental investigations including microstructure and mechanical properties characterization of the weldments were determined from the established optimal parameters. The results showed that the tensile strength and the impact toughness of the joints obtained from autogeneous GTAW process were found to be 851 MPa and 150 J respectively.