Experimental study on laser peen texturing and tribological properties of E690 high-strength steel

To investigate how laser peen texturing (LPT) parameters affect the patterns formed on the surface of E690 high -strength steel, and how these patterns subsequently influence tribological properties, the LPT process, including multiple shocks, was simulated by ABAQUS and verified by experiments. The residual stress and microstructure on the surface of micro-dimples after LPT were measured and observed by X-ray stress analyzer and transmission electron microscope. The tribological properties of specimens with different LPT density and depth were tested by reciprocating friction experiments, and the worn surfaces were observed using a scanning electron micro-scope. The experimentally obtained plastic deformation depths of the micro-dimples were -8.82 mu m,-18.31 mu m,-28.72 mu m and -36.34 mu m when the shock number was varied from 1 to 4. The simulation and experiment results were within 3.3 %, verifying the accuracy and reliability of the simulation. When the shock number was >= 2, the residual stress values in all directions at the test points within the micro-dimples tended to be consistent, and the full width at half maximum (FWHM) values gradually increased with increasing shock number. The TEM images and electron diffraction pattern of the specimen after three shocks showed that nanocrystals are formed on the bottom surface of the micro-dimple. In the friction experiments, the average friction coefficient first decreased and then increased with increasing LPT density. The average friction coefficient was the lowest when the LPT density was 20 %, for a constant micro-dimple depth. When the LPT density was 20 %, increasing the micro-dimple depth had little effect on the average friction coefficient, but the stability time of the specimens increased substantially. The wear surface of the untextured specimen showed deep and wide wear marks, and serious abrasive wear and adhesive wear occurred. Suggested LPT parameters for optimum wear resistance are an LPT density of 20% and shock number of 3.