Tribology of laser modified surface of stainless steel in physiological solution

Abstract

The laser surface treatment of stainless steel (SS) 316L, an important alloy for biomedical applications, was used to improve its corrosion and wear-corrosion resistance in bio-environment. Microstructural and X-ray diffraction (XRD) pattern analysis showed presence of an austenitic phase in both untreated and laser-treated SS316L. Laser melting produced homogenized and refined microstructure on the surface with higher hardness (143–171 HV) compared to untreated SS316L (131 HV). Increase in intensity of γ (200) peaks in XRD pattern for laser-treated ( > 800 W) SS316L indicated possible crystallographic orientation along γ (200) plane. Passive currents were reduced to < 2.8 µ A/cm 2 and pitting potentials was increased to >+ 344 mV for samples laser surface treated at greater than 1200 W. The volume-loss and wear-rate of laser-treated SS316L were significantly reduced compared to untreated sample. Abrasive wear was the main wear mechanism for both untreated and laser surface treated SS316L. Wear particles/debris were found to be cold welded on the surface of SS316L and showed brittle cracking with further wear-straining.