Through the combination of experimental simulation and experiment, the improvement effect of laser melting, laser shock and graphitization annealing process on the surface properties of gray cast iron is verified. The changes of residual compressive stress on the surface of gray cast iron during laser melting and laser shock are simulated and analyzed. Through experiments, the changes of matrix structure and graphite phase on the surface of gray cast iron under different process parameters are compared, and the process parameters are optimized to suppress the cracks on the surface of gray cast iron after laser melting, improve the hard and brittle defects of laser melting impact layer of gray cast iron after graphitization annealing, and realize the transformation of graphite on the surface of gray cast iron to fine flocculent, The properties of the surface layer of gray cast iron are improved. However, due to the limited time and experimental conditions, it is impossible to conduct a more in-depth study on the composite process of laser melting, laser shock and graphitization annealing of gray cast iron. The following aspects need to be studied:
(1) In the process of laser melting experiment of gray cast iron, only the influence of residual tensile stress on the surface crack of gray cast iron is discussed, but the change of residual tensile stress in heat affected zone and its influence on crack initiation and propagation in heat affected zone are not deeply studied, In the follow-up study, the change of residual tensile stress in heat affected zone and the mechanism of crack initiation and propagation need to be discussed.
(2) In the process of laser shock, only the changes of residual compressive stress and microstructure in the plastic deformation layer after laser shock are analyzed, but the dislocation accumulation and grain refinement mechanism in the grains of gray cast iron melting layer after laser shock are not studied. In the follow-up research, the experimental verification of gray cast iron melting layer after laser shock needs to be carried out with the help of transmission electron microscope.
(3) In the process of graphitization annealing, only the effects of different annealing temperatures on the microstructure and graphite phase change of laser melting impact layer of gray cast iron are analyzed. However, the holding time and cooling time of continuous annealing in the process of annealing are not fully studied, which should be considered in the actual process.