A numerical solution for laser heating of titanium and nitrogen diffusion in solid

Laser gas assisted heating offers considerable advantages in surface treatment of engineering metals. Modeling of the heating process minimizes the experimental costs and provides process optimization. In the present study, laser heating of titanium is considered. The conjugate heat transfer taking place due to gas impingement and laser heating is modeled. A Fourier heat transfer model is employed for the solid heating while flow equations are taken into account for the gas jet impingement. The low-Reynolds number k-ε model is considered to account for the turbulence. The study is extended to include calculation of nitrogen diffusion coefficient into the solid substrate using previous experimental results. It is found that the temperature rise in the solid substrate is considerable in the onset of laser pulse; however, as the heating progresses, the temperature rise attains almost a steady value. The cooling effect of the impinging gas is minimal in the heating cycle. The nitrogen diffusion depth is only 10^-6 cm in the central region of the heated spot and it does not extend considerably into the solid substrate in the axial direction.