Surface/subsurface generation and microstructure evolution of iron in ultra-high-speed machining

J Chen and CL Liu and TF Yin and LH Sun and H Liu and B Zhang and S To, INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES, 307, 110906 (2025).

DOI: 10.1016/j.ijmecsci.2025.110906

Ultra-high-speed machining (UHSM) shows great promise for improving the machinability of ferrous metals. However, elucidating the surface formation mechanisms of iron at ultra-high speeds remains challenging due to the difficulty of experimentally capturing microstructural evolution in real time. In this study, molecular dynamics (MD) simulations are integrated with experiments to investigate surface and subsurface generation in UHSM of polycrystalline iron. The effect of machining speed on surface morphology and subsurface damage is systematically analysed. Results reveal that surface roughness first decreases and then increases as machining speed rises, driven by the interplay of mechanical and thermal effects. Subsurface analysis shows a notable reduction in damage depth at 200 m/s compared with 50 m/s. Furthermore, dynamic recrystallization-induced grain refinement and stress-driven lattice rotation are identified within the subsurface layer. This work links atomic-scale mechanisms with experimentally observed microstructural changes. The findings deepen the mechanistic understanding of surface/subsurface evolution under UHSM conditions and provide valuable guidance for optimizing machining parameters to enhance surface integrity.

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