Influence of microstructural inhomogeneities on the fracture toughness of modified 9Cr–1Mo steel at 298–823 K

• Published in: Journal of nuclear materials 2012-02, Vol.421 (1), p.15-21
• Main Authors: Shashank Dutt, B., Nani Babu, M., Shanthi, G., Venugopal, S., Sasikala, G., Bhaduri, A.K.
• Format: Article
• Language: English
• Subjects: Applied sciences; Chromium molybdenum steels; Controled nuclear fusion plants; Crack propagation; Density; Ductile fracture; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Fission nuclear power plants; Fracture mechanics; Fracture toughness; Fracturing; Fuels; Installations for energy generation and conversion: thermal and electrical energy; Microstructure; Nuclear fuels; Steels
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/j.jnucmat.2011.11.035

► Fracture toughness of modified 9Cr–1Mo steel have been assessed. ► At 298 K cleavage fracture occurred in one heat. ► At 653 and 823 K fracture in both materials was by ductile crack growth. ► The difference in behaviour has been discussed. Quasistatic fracture behaviour of two heats of modified 9Cr–1Mo steel for steam generator applications have been assessed at 298, 653 and 823 K. J– R curves were established and the elastic–plastic fracture toughness values at 0.2 mm crack extension ( J 0.2) were determined. The fracture mechanisms were entirely different for the two steels at 298 K, with brittle fracture controlled by cleavage crack initiation in one and ductile fracture in the other by void nucleation and growth. At 653 and 823 K, fracture in both materials was by ductile crack growth. The difference in behaviour between the two steels at 298 K was attributed to the differences in microstructure, distribution and density of inclusions as well as phosphorous contents.