Surface Residual Stress and Friction Wear Behavior of Vermicular Graphite Cast Iron after Laser Remelting

Numerical simulation and laser remelting experiments were conducted to investigate the microstructural evolution and changes in residual stress of vermicular graphite cast iron. The results demonstrate that during the remelting process, Fe and C elements interact to form Fe₃C, transforming the microstructure from ferrite and worm-like graphite to a mixture of martensite and lysite. These changes contribute to a remarkable 3.49-fold increase in hardness and a significant 0.857-fold decrease in wear rate after remelting. The increase in residual stresses after remelting can be attributed to rapid thermal expansion and solidification stresses during cooling, resulting in a 51.1% increase in residual stresses perpendicular to the laser scanning direction and a 76.9% increase in the parallel direction. Additionally, the experimentally obtained residual stresses in the remelted zone were 10.1 and 6.4% higher than the simulated results in the perpendicular and parallel laser scanning directions.