Influence of chemical composition on Mn temperature and amount of residual austenite. Influence of quench heating temperature on the amount of residual austenite. Influence of quenching cooling mode on the amount of residual austenite. Decay of residual austenite on tempering; Influence of residual austenite on structural heredity. Effects of stress and plastic deformation on martensitic transformation. Influence of residual austenite on steel mechanical properties. Stepwise and isothermal quenching. Residual austenite and thermomechanical treatment.