Laser heating process and experimental validation

Laser machining of engineering materials requires deep investigation into the laser-workpiece interaction mechanism, which is generally complicated and depends on the laser and workpiece properties. The present study examines the heat transfer mechanism, including conduction, phase change and convection processes taking place during Nd YAG laser irradiation of steel workpieces. Gaussian profile is considered for the spatial distribution of the laser output power intensity, while a time-dependent profile resembling the actual laser output pulse is introduced in computation. The thermal properties of the substance is considered as temperature dependent. Mass removal from the laser irradiated spot is modeled considering momentum and continuity equations. To validate the theoretical predictions, experimental measurements of surface temperature and evaporating surface velocities are carried out. Optical method and streak photography techniques are employed for this purpose. It is found that surface temperatures and evaporating front velocities are in good agreement with the experimental results. Copyright (C) 1996 Elsevier Science Ltd.