Publication: Ductile-brittle transition temperatures and dynamic fracture toughness of 9Cr-1Mo steel
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Date
2005
Journal Title
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
Journal ISSN
Volume Title
Publisher
Minerals, Metals and Materials Society
Abstract
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.