The synergy of fireside corrosion and stress is one of the challenges for austenitic steels used in modern fossil-fuel power plants during their service process. The creep rupture tests of Super 304H steel are carried out under static air and fireside corrosion environment at 650 ℃. The stress range is set at 200 to 300 MPa. The creep rupture life and microstructure evolution of different samples were studied. The results show that creep rupture life of Super 304H steel in corrosion condition decreases significantly

compared with that in static air. The rupture life decreases more seriously as the stress decreases

up to 83% at 200 MPa. The complete and continuous corrosion products scale is damaged by fireside corrosion

including the occurrence of cracks and spallation of these surface products. The formation of internal sulfide in the matrix caused by fireside corrosion leads to the deterioration of grain boundaries. Then it tends to crack along grain boundaries during creep rupture tests to accelerate the accumulation of creep damage. The surface of matrix undergoes recrystallization upon to the combination of high temperature and stress due to the loss of alloy elements caused by corrosion/oxidation. The formation of these fine recrystallized grains is unfavorable to creep properties of metals. The ferrite transformation also occurs in the same area during the cooling process after creep tests. Fireside corrosion increases the width of recrystallized grains area

thus expands its influence on the creep rupture life of the alloy. The fireside corrosion accelerates the creep rupture of Super 304H steel by promoting its corrosion process and the microstructure evolution.