Investigation into thermoelastic displacement of surfaces subjected to gas assisted laser repetitive pulse heating

Gas assisted laser repetitive pulse heating of metallic surfaces finds wide application in industry. As the temperature inside the substrate material rises, thermal expansion of the irradiated region occurs. The monitoring of the surface displacement is a potential candidate for measuring the surface temperature during the laser heating process. In the present study, gas assisted laser repetitive pulse heating of steel is modelled. The strain in the surface vicinity and the thermoelastic displacement of the surface are predicted for two pulse types. The correlation between the surface temperature and the surface displacement is explored. It is found that the surface displacement follows the frequency of the temperature profiles; however, the rise and fall of the rates of the surface displacement differ considerably from those of the temperature field. This is more pronounced for the repetitive pulses with long cooling periods. In addition, the spatial resolution of the surface displacement differs from the spatial resolution of the surface temperature across the irradiated surface.