STP520: Strain Rate and Holdtime Saturation in Low-Cycle Fatigue: Design-Parameter Plots

    Conway, JB
    President, vice-president of engineering, and vice-president of research and development, Mar-Test Inc., Cincinnati, Ohio

    Berling, JT
    President, vice-president of engineering, and vice-president of research and development, Mar-Test Inc., Cincinnati, Ohio

    Stentz, RH
    President, vice-president of engineering, and vice-president of research and development, Mar-Test Inc., Cincinnati, Ohio

    Pages: 11    Published: Jan 1973


    Abstract

    A detailed study is made of the effect of strain rate and hold periods on the low-cycle fatigue behavior of AISI 304 stainless steel at 650 C (1200 F). Data are presented in terms of a logarithmic plot of Nf versus cycle time to reveal several important regimes. At very small cycle times the fatigue life is independent of strain rate. As the strain rate is decreased the fatigue life is reduced and finally a saturation effect is noted at a strain rate close to 4 × 10-4 s-1. In the region prior to saturation, strain rate and hold periods have the same effect on fatigue life as long as they are compared at the same cycle time. Hold-period effects also exhibit a saturation effect, but this occurs at a fatigue life lower than that corresponding to the strain rate saturation level. For hold periods in tension only the holdtime effect is shown to be dependent upon the strain rate employed in that portion of the cycle exclusive of the hold period. Design-parameter plots are introduced to provide an extensive presentation of fatigue data and a graphical solution for the fatigue life at a given temperature once values for strain range, strain rate, and hold period are selected.

    Keywords:

    fatigue (materials), fatigue tests, strain rate, holdtime, stainless steel, saturation, correlation, design-parameter plots


    Paper ID: STP38875S

    Committee/Subcommittee: E08.05

    DOI: 10.1520/STP38875S


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