The effect of excimer laser surface treatment on pitting corrosion resistance of 316LS stainless steel

Excimer laser surface treatment. of 316LS bio-grade stainless steel (ASTM-F 138) was conducted with the aim of enhancing the pitting corrosion resistan ce of the material. The experiment was performed under two different gas en vironments: air and nitrogen. The microstructure, phase and compositional c hanges after laser treatment were characterized by means of XRD, XPS and ED X; the resulting pitting corrosion resistance was evaluated by electrochemi cal polarization tests. The results show that excimer laser surface melting can effectively eliminate carbides and second phases alike, and also serve s the function of homogenizing the microstructure. Nitrogen induced into th e laser-treated surface could promote new precipitates and as a result lowe red the corrosion resistance. On the other hand, laser treatment in a low p artial pressure of nitrogen could enhance the corrosion resistance of 316LS stainless steel in that the active corrosion current was reduced and the p assive range was widened. (C) 2001 Elsevier Science B.V. All rights reserve d.