Effect of Surface Mechanical Attrition Treatment on Microstructure and Oxidation Behavior in T91 Steel at High Temperature

Abstract

Traditional techniques and methods can not resolve the contradictions of the microstructure requirement between creep resistance and oxidation resistance in T91 steel at high temperature. In the present work, oxidation resistance of T91 steel were successfully improved by surface mechanical attrition treatment (SMAT). The variations of ferrite grains and precipitation behavior in the surface layer at different tempering temperature were also observed to investigate thermal stability. A FeCr₂O₄ spinel inner layer with higher Cr content could rapidly form and protect the material from further oxidation in T91 steel due to the nanocrystalline surface layer.