The Formation of Multiphase Microstructures in Low-Alloy Steel

Abstract

Although relatively simple in its chemical composition, low-alloy steel can form in a wide variety of microstructures, which directly implies that the (mechanical) properties of the material can vary strongly. Mankind has been using this to his advantage for ages, but the requirements for modern production and use of the material necessitate an ever better insight in the formation of these microstructures. Newly developed steel grades like DP-steel (Dual-Phase) or TRIP-steel (Transformation-Induced Plasticity) consist of several of the well-known phases ferrite, bainite, martensite, austenite, which need to be carefully balanced in their amount, composition and morphology to attain the desired material properties. An overview is given of the basic principles of microstructure formation in low-alloy steel, and the implications for several types of multiphase steel microstructures, in relation to the mechanical properties, are discussed.