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Stainless steel 441 was oxidized in water vapor containing atmospheres at 1,000 °C to study the contrary effects of water vapor on the oxidization process. The steel in 3.5 vol. % H2O containing atmosphere exhibited an relatively strong protective behavior. The reason was that the densification of the chromium oxide scale was promoted due to the sintering of the oxide grains via Cr-containing species vapor. But the oxidation of the steel in 11.5 ~ 15.6 vol. % H2O containing atmosphere followed a non-protective breakaway oxidation due to the breakage of the dense scale by “bubbles” and the formation of iron-rich oxides layer. Experimental result shows that the growth stress increased about 2 GPa during the first 70 ks in wet oxidizing atmosphere. The relatively slow increase of the oxides scale growth stress could be release in water vapor containing atmosphere.