Characterization Of The Oxides Formed At 1000 ℃ On The Aisi 316l Stainless Steel—role Of Molybdenum

摘要

In the present work, in situ X-ray diffraction (XRD) was used to identify the oxides formed on the AISI 316L stainless steel (SS) during isothermal oxidation at 1000 ℃, in air. The results were compared with those obtained on the AISI 304 SS in order to better explain the role of molybdenum on the oxidation process of the AISI 316L (containing 2% Mo). A good oxidation behavior is observed on the AISI 316L considering kinetics, structural characteristics and scale adherence. It is shown that molybdenum plays a similar protective role as the one observed with silicon. Moreover, it is possible to add a higher content of molybdenum in the stainless steel compared with silicon (usually 0.5 wt%). This higher protective element content hinders the external iron diffusion and leads to the lower growth rate and the better scale adherence. The oxide scale is then composed of Cr_2O_3 with a small amount of Mn_(1.5)Cr_(1.5)O_4 at the external interface. The better scale adherence appears to be also related to a pegging effect at the internal interface.