At present, laser hardening is quite widely used for surface hardening of machine parts, dies, and tools. However, the processing parameters, such as beam spot diameter and surface condition of materials, can be kept only seldom consistant in practice. Therefore, numerical analysis is needed for the systematic data on the process, purely experimental results have always been dubious of general application.
It is well known that the thermal and residual stresses can occure during the surface heat treatment of machine parts, such as flame, induction and laser surface hardening. However, to analyze the distribution of the residual stresses which has a great influence on the mechanical properties of the heat-treated parts, the problem of the heat flow must be solved at first.
In this study, the heat flow problem during laser hardening process was numerically analyzed by using a finite difference method, and the calculated $A_c1$-isothermal lines were compared with the heat affected zone boundaries which could be visualized through the macroscopic etching technique. The calculated and experimental HAZ shapes and sizes were in relatively good agreement for various process parameters. The thermal and residual stresses were then numerically determined by using a finite element method.
