Progress in effect of alloying element partition on thermodynamics and kinetics of pearlite transformation and its austenitization

Abstract

Pearlite transformation and its re-austenitization process, which involve triple phases and dual phase interfaces, have been considered difficult phase transformation processes. Thus, the mechanism and physical nature of them are waiting to be studied. The partition of carbon and substitutional alloying element M during transformation by integrating the previous results were clarified. Moreover, the application of phase field method in the pearlite transformation was introduced. Based on the large amount of the experimental and calculated results, the influence of the inhomogenous microstructure and composition on the re-austenitization from pearlite were further discussed. Partitional and non-partitional transformed temperature (PNTT), which is due to the large difference of diffusion coefficient between C and M, was further studied. Based on this, a new heat treatment of near-eutectoid Mn-contained steel has been put forward. The segregation of Mn in retained austenite can be significantly improved compared to the traditional Q&P treatment, and then the stability of the retained austenite can be enhanced and the guidance can be provided for controlling the martensite/austenite dual phase microstructure more systematically.

Keywords

• pearlite transformation
• austenitization
• thermodynamic
• kinetics
• alloying element partition