Effect of machining on oxide development in type 316L stainless steel in high-temperature hydrogenated water

Abstract

The oxidation mechanisms of 316 L stainless steel in high-temperature hydrogenated water were investigated on machined and polished surfaces via complementary analytical techniques. The differences in microstructure of the surfaces and of the inner oxides were shown to be responsible for the fast oxidation on machined surfaces. In fact, machining promoted the formation of a ∼2 μm thick ultrafine-grained layer which developed a more porous and fine-grained inner oxide than on that formed on polished surface. The faster oxidation kinetics of machined surfaces was attributed to the accelerated oxygen anions and metal cations diffusion through the oxide pores and grain boundaries.