Abstract
In this paper, the equivalent stress range was proposed as a new mechanical parameter controlling the biaxial low-cycle fatigue life of a heat resistant steel at elevated temperatures. Push-pull and torsional tests were conducted on an austenitic stainless steel of SUS304 at 296K, 723K, 823K and 923K with a frequency of 0.1Hz in air. The reason for selecting these four temperatures was to vary the constitutive relation of the material tested. The conclusions obtained are as follows.
(1) The maximum principal stress was inadequate to compare the fatigue lives in push-pull tests with those in torsional tests at all the temperature levels from 296K to 923K.
(2) Both the maximum principal stress and the temperature level did not influence the accerelation of crack propagation rate caused by the minimum principal stress parallel to the crack.
(3) The equivalent stress range, Δσ*, including the effect of principal stress parallel to the crack is a good parameter for arranging low-cycle fatigue data obtained in biaxial tests at temperatures ranging from 296K to 923K.
