Physicochemical surface effects with surface active media on ductile metals have been repeatedly shown to reduce the strength of metals under the Rehbinder effect due to the believed preferential chemical interaction between surface-active media molecules and the work material that reduces the energy for new surface generation [1]. This topic has been hotly investigated in the recent years, but our group exclusively studies this phenomenon on the micro-scale of ultra-precision machining where we have identified several benefits of the reversible effect on various metals (e.g., copper, aluminum alloys, steels). These include reduced cutting force by up to 50% [2], improved machined surface roughness [3], and improved wear resistance of diamond cutting tools [4]. Unique to our method of investigation, we connected the dots between the proposed chemisorption surface activity on the free surface of chips that struck a chord with heat generated during cutting that tied in with substantial differences in the machined surface microstructure evolution [5,6] and cutting chip grain morphology [7]. While our research is consistent with the common understanding that the mechanochemical effect largely affects ductile metals [8], we have also identified the manifestation of this phenomenon in much stronger materials, such as additively manufactured maraging steel [9] and high entropy alloys [10]. The simplicity of this phenomenon in applying a surfactant to reap massive benefits in micro-cutting performance has also been evaluated as a highly sustainable approach with nearly negligible release of contaminants into the machining environment [11].

Publications

[1] Y.J. Lee and H. Wang, Current understanding of surface effects in microcutting, Materials & Design, 192 (2020) 108688.

[2] A. Chaudhari and H. Wang, Effect of surface-active media on chip formation in micromachining, Journal of Materials Processing Technology, 271 (2019) 325–335.

[3] Z. Zheng, et al., Ultra-precision micro-cutting of maraging steel 3J33C under the influence of a surface-active medium, Journal of Materials Processing Technology, 292 (2021) 117054.

[4] Y.J. Lee, Y-.K.. Shen, H. Wang, Suppression of polycrystalline diamond tool wear with mechanochemical effects in micromachining of ferrous metal, Journal of Manufacturing and Materials Processing, 4 (2020) 81.

[5] J. Zhang, Y.J. Lee, H. Wang, Surface texture transformation in micro-cutting of AA6061-T6 with the rehbinder effect, International Journal of Precision Engineering and Manufacturing-Green Technology, 8 (2020) 1151–1162.

[6] J. Zhang, Y.J. Lee, H. Wang, Mechanochemical effect on the microstructure and mechanical properties in ultraprecision machining of AA6061 alloy, Journal of Materials Science & Technology, 69 (2021) 228–238.

[7] J. Zhang, Y.J. Lee, H. Wang, Microstructure evaluation of shear bands of microcutting chips in AA6061 alloy under the mechanochemical effect, Journal of Materials Science & Technology, 91 (2021) 178–186.

[8] A. Chaudhari, et al., Rehbinder effect in ultraprecision machining of ductile materials, International Journal of Machine Tools and Manufacture, 133 (2018) 47–60.

[9] Y. Bai, et al., Efficient post-processing of additive manufactured maraging steel enhanced by the mechanochemical effect, International Journal of Machine Tools and Manufacture, 193 (2023) 104086.

[10] L. Xu, et al., Abnormal mechanochemical effect in ultraprecision machining of an additively manufactured precipitation-strengthened high-entropy alloy, Journal of Materials Science & Technology, 170 (2024) 221–237.

[11] Y.J. Lee and H. Wang, Sustainability of methods for augmented ultra-precision machining, International Journal of Precision Engineering and Manufacturing-Green Technology, 11 (2024) 585–624.

Acknowledgements

This research is proudly supported by the Singapore MOE Academic Research Fund Tier 2 Grant (MOE-T2EP50120-0010).