Abstract
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The strengthening and fracture mechanisms of Fe���20Ni���14Cr���2Cu alumina-forming austenitic (AFA) steel during creeping at 973��K/130��MPa were systematically investigated. Microstructural observations show that during creep after priorly aged at 973��K for different times, three main types of precipitates, i.e., Laves, B2-NiAl, and �� phases, are found in Fe���20Ni���14Cr���2Cu AFA steel. Laves and B2-NiAl phases dispersed in austenitic matrix contribute to the creep properties of AFA steel due to their small particle sizes, while the coarsening of hard-brittle �� phase in ��-ferrite region seems to be the main reason for creep failure. The Fe���20Ni���14Cr���2Cu AFA steel priorly aged for 1000��h possesses excellent creep property at 973��K with the minimum steady-state creep rate of 7.64 �� 10���6��s���1 and the longest creep life of 329.5��h. The contribution of Laves and B2-NiAl phases to creep strength of AFA steel at 973��K/130��MPa after priorly aged for 1000��h is 261.2��MPa.