Study On The Oxidation Behavior Of Austenitic Stainless Steel In High Temperature Contains Water

With the developing of China's economy,many serious environment pollution issues are raised by energy producing process.To solve these problems,higher efficiency of energy production is required.Since the major power plant is coal-fired in our country that it is urgent to improve the efficiency.However,this improvement will lead harsh environment that materials serve in.So,material is the barrier for higher working efficiency of coal-fired power plant.Two optional materials for Ultra Supercritical Power Plant are researched in the environment with water at high temperature in this paper.These works include the oxidation behavior of the austenitic stainless steel 304 in the supercritical water and the oxidation mechanism of Al₂O₃-forming austenitic stainless steel?short for AFA in this paper?in the atmosphere with water vapor at high temperature.The result shows that oxide formed on the austenitic stainless steel 304 in the supercritical water at 700?and 25MPa cannot prevent the substrate from being further oxidized,so this alloy is not suitable for this environment.In this environment,the diffusion of cation outward and anion inward accounts for the growth of oxide scale on 304ss at the early stage.During the middle and final stages,the consumption of chromium in the substrate increases greatly by quick diffuse of oxidant inward.Meanwhile,more alloy elements for non-protective oxide diffuse outside,which also leads the breakaway oxidation.The oxidation behavior of AFA shows this alloy can service stably in O2+10%H2O environment at 800?.Due to the compact inner Al-rich oxide scale effectively decreases the oxygen pressure at the interface of substrate and oxide scale that the diffusion of Mn and Cr ions outward is significantly reduced.This phenomenon leads neither spinel type oxide nor volatile oxide can be formed,which also prevents the formation of holes in the oxide scale.