Pulsed Laser Irradiation of the Surface of AISI 1045 steel and the Effects Thereof: Residual Stress, Surface Hardness and Surface Morphology

The effects produced by the Nd:YAG pulsed laser irradiation on the surface of the AISI 1045 steel were studied and the forming mechanism of the three-dimensional (3-D) surface morphology was proposed and discussed. Meanwhile, the detecting and controlling methods for the thermal damage were proposed. The results show that the transformation of the residual stress state and the surface hardness state can be attributed to the phase-transformation-induced microstructure change. The noticeable sink mark is produced at the Nd:YAG pulsed laser induced thermal damage area owing to the combined effect between the high energy pulsed laser and the surface tensile residual stress field. The findings confirm that the thermal damage can be detected by acquiring the surface residual stress, the surface hardness and the surface 3-D morphology; furthermore, the closed-loop control method and the open-loop control method can be applied to control the thermal damage.