Oxidation Behaviors Of Austenite Heat Resistance Stainless Steel 310S Under High Temperature

The thermal power generation is the main way of generating power in China at present and the ultra-supercritical thermal power unit with large capacity and high parameters is the effective way to improve the efficiency of thermal power generation.Corresponding to the requirement of the material is also higher,so it is important to develop the material used in thermal power units.Austenite heat resistance stainless steel 310 S has been used as research object and its isothermal and cyclic oxidation behavior at 800??900??1000 ??1100? and 1200? has been studied.The results shown as:Isothermal and cyclic oxidation kinetic curves at each temperatures obey parabolic law showing good oxidation resistance at high temperatures.The oxidation rate and oxidation weight gain increase with the increase of oxidation temperature,and with the oxidation time prolongs,oxidation rate is continually reduced then retains stable.The oxidation products of 310 S austenitic stainless steel at different temperatures were lamellar or rod structure Cr2O3 and spinel structure MnCr2O4,and with the increase of oxidation temperatures and oxidation time,the content of Cr2O3 is decreased and the content of MnCr2O4 is increased.It can be seen that the oxide film occurs delamination at each temperature,and the outer layer composed of spinel MnCr2O4,the middle layer composed of Cr2O3,and the inner layer composed of Si O2.With the increase of oxidation temperature,the thickness of oxide film is increasing and Cr2O3 emerge internal oxidation at 1100?.Austenite heat resistance stainless steel 310 S has good high temperature oxidation resistance at 800??900??1000 ??1100? and 1200?,and the dense MnCr2O4,Cr2O3 and SiO2 can prevent further oxidation.There are some cracks and shedding phenomenon due to internal oxidation of the inner discontinuous SiO2.The oxidation products and surface morphologies of isothermal oxidation and cyclic oxidation are similar,there are some different that the content of MnCr2O4 is higher and the surface is more rough in cyclic oxidation,indicating good cyclic oxidation resistance of 310 S steels.It can be seen from the metallographic analysis that the matrix grains grow rapidly and the second phases precipitate after high temperature oxidation.Abundant second phases,probably being ? phases or carbide,precipitate and some of them distribute along rolling direction at 800? and 900?.The amount of precipitates is reduced at1100? and 1200? and those probably being tiny oxides due to internal oxidation.