Browsing by Author "Mannan, S.L."

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    PublicationArticle
    Ductile-brittle transition temperatures and dynamic fracture toughness of 9Cr-1Mo steel
    (Minerals, Metals and Materials Society, 2005) Moitra, A.; Sreenivasan, P.R.; Mannan, S.L.; Singh, V.
    The ductile-brittle transition temperature (DBTT) of 9Cr-1Mo steel was characterized by an RTNDT-based KIR curve approach and a reference temperature (T0)-based master curve (MC) approach. The MC was developed at a dynamic loading condition (loading rate of 5.12 m/s), using precracked Charpy V-notch (PCVN) specimens, and the reference temperature was termed T0dy. The RTNDT and T0dy were determined to be -25 °C and -52 °C, respectively. The T0dy was also estimated from instrumented CVN tests, using a modified Schindler procedure to evaluate KJd; the result shows close agreement with that obtained from the PCVN tests. The ASME KIR-curve approach proves to be too conservative compared to the obtained trend of the fracture toughness with temperature. The cleavage fracture stress, σf*, estimated from the critical length, l*, shows good agreement with that estimated from the load-temperature diagram (2400 to 2450 MPa), which was constructed from the CVN test results. The crack initiation mechanism has been identified as decohesion of the particle-matrix interface, rather than as the fracture of the particles.
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    PublicationConference paper
    Dynamic Master Curve and ductile-brittle transition temperature of 9Cr-1Mo steel
    (2005) Moitra, A.; Sreemvasan, P.R.; Mannan, S.L.; Singh, V.
    The DBTT of 9Cr-1Mo steel has been characterised by reference temperature (T0) based Master Curve (MC) approach. The MC was developed at the dynamic loading conditions (stress intensity factor change rate ∼ 10 6 MPa√m/s at a loading rate of 5.12 m/s) using pre-cracked Charpy specimens (PCVN) following ASTM E 1921 guidelines. To minimise the inertial oscillations effect on load determination, the initial T0 was determined by tests conducted at a hammer velocity of ∼1.12 m/s; this was further converted toT0 at 5.12 m/s applying an test velocity dependent shift to T0. Thus, the T0 for 9Cr-lMo steel at dynamic condition was determined to be -52 °C Using a modified Schmdler procedure to evaluate KId from instrumented Charpy V-notch tests, T0 was also estimated for the 9Cr-lMo steel and the result shows close agreement with the T0 evaluated from the pre-cracked Charpy tests. ASME KIR-curve approach proves to be too conservative compared to the real trend of the fracture toughness with temperature.