Effect of rare earth elements on microstructure and oxidation behaviour in TIG weldments of AISI 316L stainless steel

The influence of rare earth addition in weld metal, on the microstructure and oxidation behaviour of AISI 316L stainless steel in dry air under isothermal condition at 973 K for 240 h is reported. Rare earth metal (REM) doped weld metal zone exhibits better oxidation resistance during isothermal holding as compared to base metal and undoped weld metal zone of 316L. Presence of both Ce and Nb in weld metal shows superior oxidation resistance than with Ce alone. TIG weld microstructures are presented by optical microscopy. The morphologies of the scales and nature of their adherence to the alloy substrates, and scale spallation have been characterized by SEM and EDAX.