The effects of grain refinement and deformation on corrosion resistance of passive film formed on the surface of 304 stainless steels

The nanotultrafine grained stainless steel promoted the form of more deformation nanotwins and inhibited dislocation slip and strain induced alpha'-martensite transformation during deformation compared with coarse grained stainless steel. The diffusivity of the point defects in passive film in coarse grain stainless steel was lower than that in nano/ultrafine one. The corrosion resistance of nano/ultrafine grained stainless steel was improved by reducing content of strain induced alpha'-martensite. Moreover, the donor and acceptor densities in passive film formed on the stainless steel increased due to more strain induced alpha'-martensites and more chloride ions. Fewer strain induced alpha'-martensites and more nanotwins in nano/ultrafine grained stainless steel improved its corrosion resistance. (C) 2015 Elsevier Ltd. All rights reserved.