Nd:Yag Laser Butt Welding of Super Duplex Stainless Steel
N. Sivagurumanikandan, K. Raghukandan and S. Saravanan
In this study UNS S32750 super duplex stainless steel (SDSS) sheets were laser welded at different welding speeds, frequencies and focal positions using Nd:YAG pulsed laser welding machine. Whereas the weld bead profiles show complete penetration irrespective of welding speed, the microstructures of fusion zones differ. The aspect ratio of fusion zone is found to be higher at lower welding speeds. This is due to enhanced heat input which results in increase in average grain size and formation of columnar dendritic structure in the weld zones. The tensile strength and microhardness of the laser welded joints are higher than the base alloy.
Keywords: Nd:YAG laser, UNS S32750, super duplex stainless steel (SDSS), microstructure, tensile strength, microhardness