Mechanical and electrochemical behavior of nanocrystalline surface of 304 stainless steel

This paper reports our recent studies on nanocrystalline surface layer of 304 stainless steel (304SS) produced using a sandblasting and annealing process. The grain size of the sandblasted surface layer was less than 20 nm. Mechanical and electrochemical properties of the nanocrystalline surface and its passive film were investigated using nano/micro/-indentation, micro-scratch, scanning Kelvin probe (SKP), potentiodynamic scanning and electrochemical scratch techniques. It was demonstrated that the nanocrystalline surface was markedly superior to that of original 304SS with enhanced passive film. The polarization, electrochemical scratch and SKP measurements indicated that the nanocrystalline surface had higher resistance to corrosion, greater capability of repassivation and higher chemistry stability. All results demonstrated that the nanocrystallization surface did not only enhance the mechanical properties of the surface layer and its passive film, but also benefited the passivation capability of the steel with improved corrosion resistance.