The influence of hot-deformation and tempering temperature on the microstructure evolution of a 12%Cr heat resistant steel during short-term creep at 80 to 250MPa and 650C was investigated. Quantitative determination of dislocation density and sub-grain size in the initial microstructure and after creep was investigated by STEM-HAADF. A correlation between microstructure evolution and creep response was established. All crept samples showed a significant increase of sub-grain size and a reduction of dislocation density. Hot-deformed samples showed better creep strength than non hot-deformed samples due to homogenization of the microstructure. The tempering temperature affected the dislocation density and the sub-grain size evolution, influencing the creep behavior.

Effect of Processing Parameters on the Evolution of Dislocation Density and Sub-Grain Size of a 12%Cr Heat Resistant Steel during Creep at 650C. D.Rojas, J.Garcia, O.Prat, L.Agudo, C.Carrasco, G.Sauthoff, A.R.Kaysser-Pyzalla: Materials Science and Engineering A, 2011, 528[3], 1372-81