Effects of grain size on the properties of a low nickel austenitic stainless steel

The effect of the grain size (varying in the range of 2.5-50 mum) on the mechanical properties and on the wear and corrosion resistance of a low nickel austenitic stainless steel is reviewed. In particular, the austenite-martensite transformation followed by annealing for martensite reversion in high nitrogen stainless steel is investigated. In order to study the effect of this thermo-mechanical process on grain refinement, the effect of cold reduction, annealing temperature and annealing times were analysed. After obtaining ultrafine grains, the effect of the grain size on the hardness and the tensile properties was evaluated and showed a Petch-Hall dependency in the fully analysed range (down to a 2.5 mum grain size). The fatigue behaviour of the steel is studied as a function of the grain size showing a poor influence of grain refining on the fatigue resistance. An increase of both the wear resistance and of the localized corrosion resistance with grain refining is also detected. Results are compared to those of similar measurements on a standard AISI 304 steel. (C) 2003 Kluwer Academic Publishers.