5. Determination of residual stresses in surface layers

5.1 Calculation methods

The prediction of residual stresses generated by various surface heat treatments is currently part of many computer-aided design and production software packages. Figure shows an overview of the models typically used for hardening treatments after case-hardening and carbonitriding. They comprise four stages.

• The first step is to determine the transient thermal field in the part, usually using a finite element algorithm to solve the heat conduction equation and taking into account the boundary conditions imposed by the quenching medium. In the thermal conduction equation :