STP1270: On the Role of Strain Rate, Size and Notch Acuity on Toughness: A Comparison of Two Martensitic Stainless Steels

    Lucas, GE
    University of California, Santa Barbara, CA

    Odette, GR
    University of California, Santa Barbara, CA

    Edsinger, K
    University of California, Santa Barbara, CA

    Wirth, B
    University of California, Santa Barbara, CA

    Sheckherd, JW
    University of California, Santa Barbara, CA

    Pages: 25    Published: Jan 1996


    Abstract

    The fracture resistance and micromechanisms of two tempered martensitic steels were characterized over a range of temperatures by both mechanical testing and quantitative fractography. HT-9 and F-82H undergo a fracture mode transition from quasi-cleavage at low temperature to microvoid coalescence at high temperature. The transition in HT-9 is rather gradual, and the transition in F-82H is extremely abrupt. While the toughness of F-82H was higher in all cases, differences between the two steels depended on test type, strain rate and temperature. The results not only demonstrate the inherent non-uniqueness of the so called ductile-to-brittle transition temperature (DBTT), but also call into question the use of Charpy data for ranking the relative performance of various alloys. The similarities in quasi-cleavage fracture and differences in ductile fracture are manifested in the fracture surfaces and are interpreted in terms of the underlying mechanisms and microstructures.

    Keywords:

    martensitic stainless steels, fracture, ductile fracture, quasi-cleavage, ductile-brittle transition temperature, fractography, fracture reconstruction


    Paper ID: STP16509S

    Committee/Subcommittee: E10.02

    DOI: 10.1520/STP16509S


    CrossRef ASTM International is a member of CrossRef.