Residual Stress Relaxation on S355 Steel Using the Pulse Current Method Accomplished with Laser Surface Irradiation
N.H. Gu and Y.Y. Hou
The pulse current method was introduced to eliminate the residual stress in the S355 steel experimental specimens treated by Nd:YAG pulsed laser surface irradiation. One group of the experimental specimens is cooled to the room temperature, and the other group of the experimental specimens is cooled for 1 minute. Then, the two groups of the experimental specimens were treated by the pulse current. In addition, the residual stress relieving mechanism of the pulse current method was discussed. The results show that the pulse current can effectively eliminate the residual stress of the metal material, and the residual stress relieving effect of the metal material with a certain initial temperature is better than that of the metal material cooled to the room temperature. The initial temperature of the metal material can soften the metal material, which is conducive to the generation of the dislocation slip movement. In this case, the metal material with a certain initial temperature can obtain the better residual stress relieving effect.
Keywords: Nd:YAG laser, S355 steel, residual stress, pulse current, laser surface treatment, pulsed laser surface irradiation (PLSI), temperature