Inhibition of metal dusting corrosion on Fe-based alloy by combined near surface severe plastic deformation (NS-SPD) and thermochemical treatment

Abstract

Combined NS-SPD and thermochemical treatment has been used to improve the metal dusting corrosion resistance of Incoloy 800. After testing under infinite carbon activity for 20−100 h, carbon was not found in the NS-SPD region while corrosion products formed in the non-NS-SPD region. The improved resistance is a result of the NS-SPD yielding a high density of defects in the deformation zone that developed into an ultra-fine-grained structure near the surface during the subsequent thermochemical treatment. These microstructural changes increase the effective diffusion coefficient for Cr in the alloy, hence promoting the formation of a highly protective oxide scale.