Study on laser shock Wave Control Surface Stress state of NiCrBSi Cladding layer

 Chen Xiao , Chen Zhibin, Zhang Jian, et al. Study on laser shock Wave Control SurfaceStress state of NiCrBSi Cladding layer [J]. Applied laser , 2018, 38(03): 387-392.

Abstract

In order to investigate the influence of laser shock wave loading on the surface of cladding coating on its stress state, size and microstructure, a high-energy pulsed light pump YAG laser was used to control the laser shock of the NiCrBSi alloy coating. The surface stress state of alloy coating before and after laser shock control was analyzed by X-ray diffraction stress analyzer.  The microstructure of the coating was observed by scanning electron microscope, and the relationship between coating microstructure and laser shock wave implanted tensile stress was explored.  The results show that after the laser double point discrete impact, both the impact zone and the near impact zone show compressive stress, the maximum compressive stress is -350MPa. After a single-pass single-layer continuous laser shock, the maximum cladding stress is -328.74MPa and the maximum compressive stress can reach 489MPa.  Before laser shock, the unclad area of the cladding layer is more even than that of overlapping area. And the initial grains are finer. The average value of the maximum principal stress at the overlap joint of cladding coating before the shock is about 130MPa, which is similar to that of single channel and single layer. The minimum principal stress is about -20 MPa, but the stress at lap joint decreases only 250MPa after laser impact, which is similar to single-pass single layer.  The minimum principal stress.shows an average compressive stress of about -20MPa,   but the  stress drop at the overlap after laser shock  is only  250MPa, which is smaller than a single-pass single layer.