Effect of Recrystallization Temperature on Microstructure and Creep Properties of a Novel Austenitic Heat Resistant Steel Containing Aluminum

Based on a special thermo-mechanical treatment, a novel aluminum-containing austenitic heat resistant steel (AFA) was treated under different recrystallization treatment temperature (1 080, 1 200 ℃). The high temperature (700 ℃,150 MPa) creep properties and microstructure of AFA steel before and after creeping were analyzed. The results show that the temperature of recrystallization treatment had remarkable influence on the microstructure of the AFA steel. At the higher temperature of recrystallization treatment (1 200 ℃), the AFA steel with grain size about 60 μm had dispersedly and densely distributed MC precipitate with size of 10 nm, while the grain size was about 10 μm and MC precipitates became coarser with size around 50 nm and smaller distribution density at lower temperature (1 080 ℃). The AFA steel had better creep resistance treated at 1 200 ℃ than at 1 080 ℃, and the creep life of the former and the latter was about 1 530 h and 650 h, respectively.