Overview of Intermetallic Sigma () Phase Precipitation in Stainless Steels

The phase which exists in various series of stainless steels is a significant subject in steels science and engineering. The precipitation of the phase is also a widely discussed aspect of the science and technology of stainless steels. The microstructural variation, precipitation mechanism, prediction method, and effects of properties of phase are also of importance in academic discussions. In the first section, a brief introduction to the development and the precipitation characteristics (including morphologies and precipitation sites) of phase in stainless steels is presented. In the second section, the properties effect, prediction method, processing effect, elemental addition, retardation method and Thermo-Calc simulation of the phase in stainless steels are highlighted.