Laser repetitive pulse heating of steel surface: A material response to thermal loading

Laser repetitive pulse heating of the workpiece surfaces results in thermal stresses developed in the vicinity of the workpiece surface. In the present study, laser repetitive pulse heating with a gas assisting process is modelled. A two-dimensional axisymmetric case is considered and governing equations of heat transfer and flow are solved numerically using a control volume approach while stress equations are solved using the finite element method (FEM). In this analysis, a gas jet impinging onto the workpiece surface coaxially with the laser beam is considered. A low-Reynolds number k-ε model is introduced to account for the turbulence. When computing the temperature and stress fields two repetitive pulse types and variable properties of workpiece, and gas jet are taken into account. Temperature predictions were discussed in a previous study. A stress field is examined at present. It is found that the radial stress component is compressive while its axial counterpart is tensile. The temporal behavior of the equivalent stress almost follows the temperature field in the workpiece. The pulse type 1 results in higher equivalent stress in the workpiece as compared to that corresponding to pulse type 2.