Austenitization refers to heating into the austenite phase field, during which the austenite structure is formed. This article highlights the purpose of austenitization, and reviews the mechanism and importance of thermodynamics and kinetics of austenite structure using an iron-carbon binary phase diagram. It also describes the effects of austenite grain size, and provides useful information on controlling the austenite grain size using the thermomechanical process.
Quenching and partitioning (Q&P) steel is a term used to describe a series of C-Si-Mn, C-Si-Mn-Al, or other steels subjected to the quenching and partitioning heat treatment process. This article discusses the Q&P steel's chemical compositions and mechanical properties, and provides an overview of the important background and product characteristics with a focus on the automotive sheet steel application. It schematically represents the continuous annealing process, consequent phase-transformation behaviors, and forming-limit curves of Q&P steels. The article describes the parameters associated with resistance spot welding, laser welding, and metal active gas welding. It also provides useful information of retained austenite volume fraction measured by x-ray diffraction and electron backscatter diffraction. The article also examines microstructure evolution during tensile testing at different strain levels using electron backscatter diffraction.