Oxidation resistance and mechanical properties of Al2O3-forming and SiO2-forming austenitic stainless steels between 1023 K and 1173 K

To know differences in oxidation resistance and mechanical properties between Al2O3-forming and SiO2-forming austenitic stainless steels, oxidation behavior and mechanical properties were investigated in Fe-20Ni-14Cr-3Al-1Nb-0.1C, Fe-20Ni-14Cr-5Si, and Fe-20Ni-14Cr-3Si-1Nb-0.1C (in wt%) steels. The results showed that the oxidation resistance of Fe-20Ni-14Cr-3Si-1Nb-0.1C steel was comparable to that of Fe-20Ni-14Cr-3Al-1Nb-0.1C steel at 1023–1073 K but poor at 1123 K. The addition of Nb could improve the oxidation resistance in the SiO2-forming steels. The solution-treated and oxidized SiO2-forming steels showed remarkably higher ductility but lower yield strength than the Al2O3-forming steel did. The easier twinning and fewer precipitates were responsible for the remarkably higher ductility in the SiO2-forming steels.