Effect of processing parameters on the evolution of dislocation density and sub-grain size of a 12%Cr heat resistant steel during creep at 650°C

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 528; no. 3; pp. 1372 - 1381
• Main Authors: Rojas, D., Garcia, J., Prat, O., Agudo, L., Carrasco, C., Sauthoff, G., Kaysser-Pyzalla, A.R.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 25.01.2011; Elsevier
• Subjects: Applied sciences; Creep; Creep resistant steel; Dislocation density; Exact sciences and technology; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Microstructure evolution; Processing parameters; Quantitative microscopy; STEM-HAADF; Dislocation density; STEM-HAADF; Processing parameters; Creep resistant steel; Microstructure evolution; Quantitative microscopy; Hot deformation; Grain size; Creep; Heat resistant steel; Creep strength; Subgrain; Chromium steels; Dark field microscopy; Tempering; Scanning transmission electron microscopy; Microstructure
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2010.10.028

▶ Dislocation density/subgrain size evolution in 12%Cr steel studied by HAADF-STEM. ▶ Correlation processing parameters/microstructure evolution/creep curves was studied. ▶ Hot-forged samples present higher dislocation density than non hot-forged samples. ▶ Crept samples showed increase of subgrain size and reduction of dislocation density. ▶ Hot-forging enhances creep-strength due to better particle size and distribution. The influence of hot-deformation and tempering temperature on the microstructure evolution of a 12%Cr heat resistant steel during short-term creep at 80–250MPa and 650°C 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 is 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.