Fatigue Life Properties of Stainless Steels in Wide Ranged Biaxial Stress State

Abstract

Multiaxial fatigue tests consisting of push-pull loading and cyclic inner pressure were carried out using hollow cylinder specimens of type 430 stainless and type 316 stainless steels at room temperature. 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 on inner surface of the specimen. The fatigue lives of both the steels showed a similar tendency although some Pull tests take longer fatigue life when cracks initiated from inside surface of the specimen. This study investigated the crack initiation and propagation behaviors as well as the initiation of oil leakage to prove the behavior and discusses life evaluation for two steels under wide ranged biaxial stress state, too.