| This paper selects the Cr23Ni13 steel oxidized under constant temperature of 900℃ , 1100℃, 1200℃ for a long time to study the time law and the constant of oxidizing speed that this steel complies with, judge the ability of oxidizing membrane healing by itself and appraise the high temperature resistance of this steel in the high temperature. The hardness of the alloy following the change of time was analyzed by micro- hardness instrument and the alloy's hardness curve following the change of time was drawn. The OLYMPUS PME—311U microscope also observed the changing shape of organization.The testing results show the Cr23Ni13 steel has good high temperature resistance at temperature of 900℃. But with the rising of oxidizing temperature, the oxidizing speed of the alloy begins to obviously improve. The law of alloy oxidized curve has already been close to the straight line law at temperature of 1200℃. This result proves alloy has already lost anti-oxidant performance in this temperature. Because the alloy appears the 2nd phase in the high temperature, the trend of this steel's hardness with the time changing has followed this character under 3 pieces of temperature: the curve has greater wave on the initial stage of oxidizing, but the hardness of the sample and reduces with temperature increasing gradually. The hardness of the sample increased after 500 hours. Metallography experiments indicate that there are obvious twin organizations inside the alloy. And the alloy appears the 2nd phase. The hardness of the alloy changes with the appearance of phase. This result is similar with the result of hardness test.
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