Stress Analysis during Quenching and Tempering

Abstract

Analyses of stresses in the process of heat treatment of steel, especially quenching and tempering, are made from the viewpoint of the theories of plasticity and creep.
The effect of martensitic transformation during quenching is taken into consideration by introducing an unsteady thermal expansion coefficient which depends on both temperature and cooling rate. A method to predict the initiation of quenching crack is also presented.
In order to analyze the process of tempering, the flow rule of creep is given by regarding the creep function as a potential, which is the function of stress, creep strain, temperature and time, and then an equilibrium equation is formulated by the finite element technique. It is concluded that this creep analysis is useful to predict the stress relief mechanism during the tempering process.