Evolution of dislocation density, size of subgrains and MX-type precipitates in a P91 steel during creep and during thermal ageing at 600 °C for more than 100,000 h

Clara Panait (1, 2) , Anna Zielinska-Lipiec (3) , Tomasz Koziel (3) , Aleksandra Czyrska-Filemonowicz (3) , Anne-Françoise Gourgues-Lorenzon (1) , Walter Bendick (4)

1 MAT - Centre des Matériaux
2 V & M France CEV
3 AGH UST - AGH University of Science and Technology [Krakow, PL]
4 Salzgitter Mannesmann Forschung GmbH

There are rather few quantitative data on the microstructure of the 9–12%Cr heat resistant steels after long-term creep. This paper presents results of the quantitative measurement of the size of MX precipitates, subgrain size and dislocation density in a P91 steel that had been creep tested for 113,431 h at 600 °C. The same measurements were conducted in the same P91 steel in the as received conditions. Transmission electron microscopy investigations were conducted using thin foils and revealed a decrease in dislocation density and an increase in subgrain size after creep exposure. MX carbonitrides are very stable during thermal and creep exposure of P91 steel at 600 °C up to 113,431 h. Electron backscatter diffraction (EBSD) investigations also revealed a significant change in the substructure of the steel after creep exposure.

Mots clés: Dislocation density; MX-type precipitates; P91 steel; Subgrains; Creep

Domaines: Sciences de l'ingénieur [physics]; Matériaux

Clara Panait, Anna Zielinska-Lipiec, Tomasz Koziel, Aleksandra Czyrska-Filemonowicz, Anne-Françoise Gourgues-Lorenzon, et al.. Evolution of dislocation density, size of subgrains and MX-type precipitates in a P91 steel during creep and during thermal ageing at 600 °C for more than 100,000 h. Materials Science and Engineering: A, 2010, 527, pp.4062-4069. ⟨10.1016/j.msea.2010.03.010⟩. ⟨hal-00491033⟩