Study on micro-grinding mechanism and surface quality of hardened 20 vol% SiCp/Al composites

Particle-reinforced aluminum-based silicon carbide composites (SiCp/Al) are widely used in aerospace, rail transit, and other fields due to their excellent comprehensive properties. However, the incorporation of high-brittle SiC particles poses challenges in the high-performance processing of SiCp/Al composites. This study focuses on hardened 20 vol% SiCp/Al composites, establishing two-dimensional finite element cutting models for single SiC particles. Micro-grinding experiments are conducted under various processing parameters. The influence law of surface defects on individual SiC particles relative to tool position and single factor machining parameters was analyzed, revealing the micro-grinding mechanisms affecting surface and subsurface quality. The results show that the interaction among particle damage mechanisms, crack propagation directions, and the restraining effects of the Al matrix leads to diverse types of defects at different cutting positions. Both simulation and experimental observations reveal surface defects such as pits, gullies, and burrs, while subsurface damage primarily results from crack invasion, cavity interstices, and pits due to particle breakage. The experiment achieved a minimum roughness of 0.057 μm. Taking into account the thermal softening of the material and the micro-behavior of the tool-chip interface, optimal conditions for improved surface quality involve a grinding depth of 0.03 mm, a spindle speed of 12,000 rpm, and a relatively low feed rate.