Effect of silicon-ion implantation upon the corrosion properties of austenitic stainless steels

The structure of the surface layers and the corrosion resistance of austeni tic stainless steels after silicon-ion implantation, were examined. The imp lanted silicon doses were 1.5 x 10(17), 3 x 10(17) and 4.5 x 10(17) Si+ cm( -2). Implantation with all these doses gave an amorphous surface layer. Whe n samples implanted with 1.5 x 1017 Si+ cm(-2) were annealed at temperature s of 300 and 500 degrees C, their surface structure remained unchanged. Aft er annealing at 650 degrees C, the amorphous layer vanished. It was determi ned how, in terms of corrosion resistance, the amount of implanted silicon, subsequent heat treatment and long time exposure, affect highly corrosion- resistant austenitic stainless steel ( 18/17/8) in comparison to the 316L a ustenitic stainless steel subjected to the same treatment. Corrosion examin ations were carried out in 0.9% NaCl at a temperature of 37 degrees C. Afte r silicon-ion implantation the corrosion resistance of the 316L steel incre ased while that of highly resistant (18/17/8) did not. The corrosion resist ance of the investigated steels, both implanted and non-implanted, increase d with the exposure time of the samples in the test environment. (C) 1998 K luwer Academic Publishers.