Preparation of Multilayer Textures on Ductile Cast Iron and Their Tribological Performance

Ductile iron is widely used in high-load friction pairs such as engine crankshafts due to its good mechanical properties. However, in engineering applications, the failure of tribological properties is still inevitable. In this study, regular texture array, in-situ texture, and multi-layer texture were fabricated on the surface of ductile cast iron by laser processing technology. The micro-flow field simulation of the above texture array was carried out to study the influence of different texture types on the hydrodynamic lubrication effect of the friction pair surface. The tribological properties of different textured surfaces under oil lubrication conditions were tested and analyzed to explore the influence mechanism of these textures on the tribological behavior of the ductile cast iron surface. The results showed that the multi-layer texture could enhance the hydrodynamic pressure more effectively. The hydrodynamic pressure of regular array texture and in-situ texture with relative area densities of 9% and 16% increased by 14.7%, 21.1%, and 3.9%, respectively. Compared with the untextured samples, all three textured samples improved the wear resistance of the material, and the wear rate was reduced by more than 66%. The multi-layer texture combined the advantages of array texture and in-situ texture. By improving the surface hardness, enhancing the hydrodynamic effect, and improving the ability of the texture to store and capture abrasive particles in lubricating oil, the lubrication performance was further optimized. Therefore, the multi-layer texture samples showed lower friction coefficient and wear rate, which significantly improved the tribological properties of the ductile iron surface.