Equi-Biaxial Tension-Compression Low Cycle Fatigue for Type 304 and Cr-Mo-V Cruciform Specimen

This paper describes high temperature multiaxial low cycle fatigue lives of type 304 stainless steel and 1Cr-1Mo-1/4V steel cruciform specimens at 823K and 923K in air. Strain controlled multiaxial low cycle fatigue tests were carried out using cruciform specimens at the principal strain ratios between −1 and 1. The principal strain ratio had a significant effect on low cycle fatigue lives. Fatigue lives drastically decreased as the principal strain ratio increased. Multiaxial low cycle fatigue strain parameters were applied to the experimental data and the applicability of the parameters was discussed. The equivalent strain based on crack opening displacement (COD strain) developed in the paper and Γ*-plane parameter successfully predicted multiaxial low cycle fatigue lives. The crack morphology was also extensively discussed from not only the surface crack direction but also the crack inclination into the specimen.