Abstract
Laser surface engineering has been explored as a possible method for improving the functional surface properties of biomedical materials such as stainless steels and titanium alloys. This study emphasises the influence of laser surface processing, carried out at a range of laser powers from 500 to 1500 W in ambient atmosphere, on the surface microstructure and corrosion behaviour of stainless steel 316L (SS316L) and Ti–6Al–4V, and metal ions released during the corrosion process. A homogeneous surface microstructure includes columnar dendrites and fine grains in the resolidified region of SS316L. A gradual increase in grain size from the processed surface towards the substrate was revealed. The laser processing of Ti–6Al–4V produced a surface full of dendrites followed by acicular martensite in the interface region. The corrosion studies in Ringer's physiological solution showed an increase in the open circuit potential (OCP) as a result of laser surface treatment of both SS316L and Ti–6Al–4V (more noble than untreated). After laser processing, the corrosion properties of SS316L were seen to deteriorate, and those of Ti–6Al–4V to improve, as compared to their respective untreated counterparts. The variation of laser power influenced the corrosion resistance of SS316L, while that of Ti–6Al–4V did not vary significantly. Laser surface treatments at higher powers (>1000 W) reduced the leaching of specific metallic ions from SS316L and Ti–6Al–4V during corrosion in Ringer's physiological solution.
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