| Based on their low cost and proper mechanical behaviour, austenitic stainless steels have been widely used medical devices and surgical tools. However, their low wear resistance and the susceptibility to pitting corrosion in body fluids have limited their wider applications in the medical industry. Therefore, it is important to develop surface treatment methods to improve the wear and corrosion resistance of austenitic stainless steel.By using a servo-hydraulic dynamic test machine, the fretting behaviour both as-received and surface treated 316LVM plate samples against martensite stainless steel balls was studied in the Ringer's solution at various displacement amplitudes. Various examinations have been performed by means of optical microscope, scanning electron microscopy, energy dispersive X-ray, Nano-Hardness/Scratch Tester and stylus profilometer to test the anti-corrosion properties and the micro topography of the wear scars on the samples. Effect of surface modification on the anti-corrosion property and the fretting behaviour of 316LVM medical grade austenitic stainless steel was discussed. Finally, the fretting behavior of surface treatment new Ni-free medical grade austenitic stainless steel was investigated. The main conclusions can be summarized as follows:1.Low-temperature plasma carburising at 500℃, carbonitriding at 430℃and nitriding at 430℃could create a layer of "S phase" on the sample surface, which dramatically improve the hardness and elastic modulus of substrate. Even though all the surface treatments can enhance the anti-corrosion and anti-wear properties of 316LVM stainless steel to some extend, the low-temperature plasma carbonitrided at 430℃was found to be the best surface treatment method of three against the fretting wear of medical grade 316LVM medical grade austenitic stainless steels.2.The surface treatment revealed a strong effect on the fretting behaviour of the 316LVM stainless steels in terms of changes in the shape of the curves of the tangential force (Ft) versus displacement (d), the fretting regimes and the damage mechanisms involved. The gross slip started at smaller displacement amplitude for the surface-treated 316LVM samples than for the untreated one. Some cracks were observed in mixed regime on un-treated 316LVM austenitic stainless steel.However, only slight wear scars could be observed on the surface-treated samples. Finally, the surface treatment could also decrease the friction coefficient of substrate.3.The precipitate-free "S-phase" can be produced in the surface layer of ASTM F2581 new nickel-free medical grade austenitic stainless steel by low-temperature plasma carburising at 500℃.The fretting wear tests in the Ringer's solution indicated that the surface treatment by carburising at 500℃can reduce the friction coefficient and considerably increase the fretting-wear resistance of ASTM F2581 Ni-free medical grade austenitic stainless steels.
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