SYMPOSIA PAPER Published: 01 January 1996

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


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.

Author Information

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
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Developed by Committee: E10
Pages: 790–814
DOI: 10.1520/STP16509S
ISBN-EB: 978-0-8031-5328-8
ISBN-13: 978-0-8031-2016-7