As high temperature oxidation resistance of a 19Cr-13Ni-3.5Si steel is usually inferior to that of SUS 310S steel, yttrium, rare earth metals and other active metals are often added in the steels to improve the oxidation resistance.
The authers have experienced that some 19Cr-13Ni-3.5Si steels show excellent resistance to high temperature oxidation. Therefore, high temperature oxidation behaviors of 19Cr-13Ni-3.5Si steels containing 0.0001 to 0.012% sulfur have been investigated by means of isothermal and cyclic heating at temperature up to 1 200°C. It has been found that sulfur existing as an impurity in steels shows very harmful influence on high temperature oxidation resistance of 19Cr-13Ni-3.5Si steels. The steels containing extra low sulfur less than 0.001% show more excellent resistance to high temperature oxidation than SUS 310S steel, and moreover, the addition of calcium in the steels containing sulfur less than 0.001% is beneficial. It has also been found that the nonmetallic compounds containing sulfur consist of the Ca-Al-Mg-O-S in the steels with sulfur less than 0.001%, and transform into MnS with an increase of sulfur content in the steels. It is suggested that MnS compounds have harmful influence on high temperature oxidation resistance of 19Cr-13Ni-3.5Si steels.
Besides, high temperature oxidation behaviors of 19Cr-13Ni-3.5Si steels containing various amounts of sulfur were clarified.
