STP1332

    Fracture Behavior of Surface Crack Tension Specimens in the Ductile-Brittle Transition Region

    Published: Jan 1999


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    Abstract

    Surface cracked tension specimens of ASTM A533, Grade B steel plate were tested to failure in the ductile-to-brittle transition region. Two different specimen configurations were used: one configuration was loaded in tension except for the natural bending resulting from the presence of the surface crack, the second configuration had an offset test section and was pin-loaded to provide a strong bending component in addition to the tension load. For each configuration, at least seven repeat tests were conducted at each of two temperatures. All specimens failed by cleavage and the critical J-integral, Jc, was obtained using three-dimensional finite element analysis of the specimen. The FEM analysis was validated by comparison with experimental strain gage and displacement measurements taken during the tests. The results were compared with previous fracture toughness measurements on the same plate using 1.6T and 1T SE(B) specimens, 1T SC(T) specimens, 1T edge cracked SE(T) specimens, and precracked Charpy specimens. The present results exhibited the expected elevation in fracture toughness and downward shift in the transition temperature compared to the highly constrained, deeply cracked SE(B) specimens. The master curve approach was used to characterize the transition curves for each specimen geometry and the shift in the transition temperature was characterized by the associated reference temperature. The master curves from the pre-cracked Charpy specimen sets tested here do not accurately predict the full constraint master curve and are non-conservative even in comparison with the tension loaded surface crack specimens and short cracked SE(B) specimens.

    Keywords:

    surface crack, fracture toughness, constraint, A555B steel, J-integral, master curve, reference temperature, ductile-to-brittle transition


    Author Information:

    Joyce, JA
    Professor and Assistant Professor, U.S. Naval Academy, Annapolis, MD

    Link, RE
    Professor and Assistant Professor, U.S. Naval Academy, Annapolis, MD


    Paper ID: STP14943S

    Committee/Subcommittee: E08.08

    DOI: 10.1520/STP14943S


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