Fatigue Life Properties of Stainless Steels in Wide Ranged Biaxial Stress States using a Hollow Cylinder Specimen

Stress controlled multiaxial fatigue tests were carried out using hollow cylinder specimens of type 430 and 316 stainless steels at room temperature. A newly developed fatigue testing machine which can apply push-pull loading and inner pressure to the specimen was used. For inner pressure, oil was put inside of the specimen. 7 types of cyclic loading paths were employed by combining axial and hoop stresses; a Pull, an Inner-pressure, a Push-pull, an Equi-biaxial, a Square-shape, a LT-shape and a LC-shape. Fatigue lives vary depending on the loading path when those were evaluated by the maximum Mises’ equivalent stress range on inner surface of the specimen. The fatigue lives of both the steels showed a similar tendency. However, the following difference was identified. Specifically, differences in fatigue lives of type 430 stainless steel between the uniaxial loading and the multiaxial tests were large, while those of type 316 stainless steel were small. To discuss difference in fatigue life properties between both steels, this study investigates the effect of the shear stress range, mean stress and additional hardening and which leads to evaluate the lives suitably