ABSTRACT
This chapter shows that interpret and use non-equilibrium diagrams and microconstituents to control the mechanical properties of materials. Whenever a non-equilibrium phase or microconstituent occurs, it is because the cooling rate has been so fast that there was insufficient time for diffusion and nucleation to take place. The mechanical properties of bainite vary between those of fine pearlite and primary martensite, depending upon the temperature at which it is formed. The non-equilibrium microstructures for many materials can be predicted solely on the basis of their equilibrium phase diagrams plus some simple experimental cooling rate and aging temperature data. Isothermal transformation diagrams are curves plotted on time vs. temperature coordinates that indicate when a supercooled solid solution will transform either to two equilibrium phases or else to a fourth metastable phase. The microstructures and mechanical properties of a given steel can be very easily determined by means of cooling rate charts and end-quench hardenability data.
