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.