Quenching and Partitioning Steel Heat Treatment

Abstract

Quenching and partitioning (QP property advancements continue to be made through research on this emerging technology. Early investigations [1] also proposed a corresponding thermodynamic model for Q&P steel and its heat treatment, which is now referred to as constrained carbon equilibrium [3]. Since first proposed in 2003, Q&P steel has gained interest for its potential to enhance properties of strength and ductility with compositions similar to transformationinduced plasticity (TRIP) steel and has been proposed as a third-generation automotive steel (Fig. 1) [4]. Many researchers [5–17] have investigated the relationship between properties and microstructures of Q&P steels subjected to various heat treatments and showed that the ultrahigh strength of Q&P steel results from martensite laths, while its good ductility is attributed to TRIP-assisted behavior of retained austenite during deformation. De Moor et al. [14] examined the stability of retained austenite and showed that the TRIP effect occurs in Q&P steels, thereby effectively contributing to the significant strain hardening. Santofimia et al. [15, 16] and Takahama et al. [17] analyzed microstructural evolution during annealing Editor’s Note The following is a preview chapter from the upcoming volume Steel Heat Treating Fundamentals and Processes, Volume 4A, ASM Handbook, Jon Dossett and George Totten, editors. The volume is scheduled for publication later this year.