21 - Physical Metallurgy of Steels

Abstract

This Chapter describes the theoretical foundations of most of the major phases that occur due to the solid-state transformation of austenite. The phases include allotriomorphic ferrite, pearlite, Widmanstätten ferrite, bainite and martensite, covering in each case the thermodynamics, kinetics and evolution of morphological features, and where appropriate, the crystallography and shape deformation of the phase concerned. Elementary mathematical derivations are included without compromising on the seminal features of particular transformations. Case studies are then presented, which show the ability of the theory to predict useful steels, for example, the TRIP and TWIP alloys, bulk nanostructured bainite, and welding materials that mitigate the development of residual stress in constrained assemblies