Effects of Multiple Overloads and Hydrogen on High-Cycle Fatigue Strength of Notched Specimen of Austenitic Stainless Steels

Abstract

To safely use of hydrogen utilization machines after large earthquakes, the effect of multiple overloads and hydrogen on high-cycle fatigue strength of SUS304 and SUS316L austenitic stainless steels were evaluated. Three kinds of notched fatigue test specimens which have different notch root radius were used. The fatigue strength of both materials was significantly reduced by multiple overloads. The cause was small cracks formed by the overloads. In SUS304, the reduction of fatigue strength became more significant by hydrogen. The cause was that hydrogen accelerated propagation of the small cracks during overloading. On the other hand, fatigue strength of SUS316L was insusceptible to hydrogen. Propagation of the small cracks existing notch root was evaluated by plastic strain range at notch root and Manson-Coffin rule in order to consider application of this study for design.

Inhibitory effect of oxygen on hydrogen‐induced fracture of A333 pipe steel

“…Table shows the result of a literature survey regarding the purity of hydrogen gas used for experiments . As described above, oxygen and other specific gas impurities contained in hydrogen gas environment have inhibitory effects on hydrogen‐induced degradation of material strength.…”

Effect of addition of oxygen and water vapor on fretting fatigue properties of an austenitic stainless steel in hydrogen

“…Regarding fretting fatigue, the environment can influence not only the fatigue properties, but also the friction or wear properties. For instance, during fatigue, hydrogen causes acceleration of the crack growth [2], and acceleration of the crack initiation during low cycle fatigue [3,4]. In wear or fretting wear, the specific wear rate in hydrogen is lower than that in air and the addition of oxygen to the hydrogen environment increases the specific wear rate [5], and the relative slip range decreases in hydrogen compared to that in air [6].…”