MECHANISMS GOVERNING THE EFFECTS OF ALLOYING ELEMENTS ON THE MICROSTRUCTURE AND PROPERTIES OF STAINLESS STEELS

Abstract

Abstract: This review article provides a systematic analysis of the mechanisms through which the principal alloying elements govern the microstructure, mechanical properties, and corrosion resistance of stainless steels. The analysis is structured according to the interrelated levels of “chemical composition–phase stability–secondary phases and inclusions–passive film–service properties.” The critical assessment indicates that Cr, Ni, and Mo establish the principal balance among passivation, ferritic and austenitic phase stability, and resistance to localized corrosion, whereas Mn, Si, S, and P modify the stacking-fault energy, inclusion characteristics, grain-boundary precipitates, and oxidation kinetics. Particular attention is given to the competition between the beneficial effects of alloying and the risks associated with the precipitation of σ and χ phases, the formation of Cr-depleted zones, and the presence of electrochemically active MnS inclusions.