Effect of Grain Size on Corrosion Resistance and High Temperature Oxidation Behavior of 22Cr-15Ni-5W Super Austenitic Stainless Steels

22Cr-15Ni-5W 슈퍼 오스테나이트계(系) 스테인리스강(鋼)의 고온산화(高溫酸化) 및 내식성(耐蝕性)에 미치는 결정립(結晶粒) 크기의 영향(影響)

The effect of grain size on corrosion resistance and high temperature oxidation behavior was studied in 22Cr-15Ni-5W super austenitic stainless steels for desulfurization equipment as a heat power station. In the high temperature oxidation test, oxidation rate was increased as the temperature increased from $600^{\circ}C\;to\;800^{\circ}C$. In vapor, oxidation rate was faster than that in air. Because the vapor was inhibited nucleation of $Cr_2O_3$ film. And the high temperature oxidation resistance at $600^{\circ}C{\sim}800^{\circ}C$ was excellent from all specimens and specimen of the smallest grain size was the most excellent. Because increasing of diffusion course through the grain-boundary was promoted nucleation and growth of $Cr_2O_3$ film. In the test temperature at $600^{\circ}C{\sim}800^{\circ}C$, Cr rich round particle oxide was formed in air, whereas Fe rich needle type oxide was developed in vapor.