Influence of Welding Speed on Microstructure and Oxidation Behaviour of Laser Welded Austenitic Stainless Steels

Microstructure and high temperature oxidation behaviour of laser weldments of 316L and 316LN steels have been found to influence by the variation in welding speed. Ferrite content and ferrite morphology change for both type 316L and 316LN laser weld with welding speed. Laser weldments consisting mainly of weld metal and base metal region of two austenitic stainless steels (ASS) were oxidized in dry air at 973 K for 240 h. Steel weldment was found to have a higher oxidation rate when joined with lower welding speed of 11.66 mm/s as compared to 25 mm/s speed. On the other hand, 316LN steel weldments have indicated much superior oxidation resistance property under similar condition. Oxidation behaviour of two ASS weldments has been correlated with microstructure and oxide scales formed over the different regions have been characterized by scanning electron microscopy (SEM/EDXA).