High-temperature creep and fatigue behaviors of AL6XN super austenite steel

High-temperature creep and fatigue behaviors of AL6XN super austenite steel were studied at 650-750 ℃ and 120-220 MPa, and 300 ℃ and 600 ℃ with different strain amplitudes, respectively. The results show that the values of stress exponent and Q for high-temperature creep are estimated to be 5.23 and 327 kJ/mol, respectively. Based on TEM observations, the mechanism of creep was considered as the dislocation climb and glide mode. The stress level of AL6XN steel in the fatigue-test at 600 ℃ is larger than that at 300 ℃, and the cycling life decreases obviously with increasing temperature and strain amplitude. TEM observations revealed dislocation tangles, rather than dislocation cells in the steel after the fatigue-test at 600 ℃, and the typical striations on the fracture surfaces without the secondary cracks are observed by SEM, which is related to the dynamic strain aging occurred in the AL6XN austenitic steel.