A method for maintaining microstructural balance of laser welded duplex stainless steel with autogenous high power laser welding process using nitrogen shielding gas

摘要

The method comprises of arranging the nozzle for supplying nitrogen gas over the workpiece at a predetermined distance in off-axial angular position and then supplying nitrogen gas at a predetermined flow rate to stabilize the austenite phase in the weld and to achieve plasma suppression when welding is carried out at a predetermined welding speed maintaining the focal plane at a predetermined height above surface with 300 mm focal length mirror to achieve a spot size of 410µm to increase the interaction time to reduce cooling rates and to increase the formation of austenite when laser beam is defocused to improve the smoothness of the weld bead by reducing the chances of undercut at low welding speeds.