Study on the improvement of laser-processed cemented carbide mechanical properties and tribological performance through confinement effect

Laser processing has been widely employed for fabricating micro-textures; however, high-energy laser ablation has led to the formation of a recast layer. The resulting heat-affected zone (HAZ) further contributes to the development of defects, such as pores and microcracks, on the surfaces of the workpieces. These imperfections have significantly impeded the practical application of micro-textured components. Inspired by the confinement effect, this study has investigated how strategically distributed micro-textures can localize the thermal influence zone of the laser and mitigate defects caused by high-energy laser ablation. Initially, the defect formation mechanism during the laser processing of cemented carbide has been analyzed. Subsequently, the confinement effect was harnessed through optimized micro-texture arrangements to mitigate the detrimental effects of laser-induced defects. The results indicated that laser direct writing led to the formation of surface defects—including recast layers, pores, and microcracks—which negatively impacted the material's mechanical properties. However, the confinement effect was found to suppress crack propagation and enhance flexural strength, resulting in a 5.3 % improvement. Friction tests demonstrated that low-density micro-textures effectively reduced the friction coefficient by acting as reservoirs for debris and friction modifiers. In contrast, high-density micro-textures compromised performance due to premature failure, thereby nullifying their friction-reduction capability.