Technique for Improving Paris-Erdogan Constants of Steels in Hydrogen Environment

Abstract

The unexpected failure of different structure components subjected to aggressive hydrogen environment and cycling are known. These phenomena occur in diverse industries such as power, oil and gas ones, etc. Special engineering models are developed to predict the crack kinetics in structure components, which are simultaneously subjected to hydrogen environment and cycling. These models enable one to estimate a structure component durability.The paper presents an empirically-specified model of crack kinetics in structure component under mentioned above conditions is presented. This model is based on the assumption that either the influence of aggressive hydrogen environment or the fatigue initiates a local fracture of structure component with a crack under mode I loading.Authors estimated a crack kinetics L(t) in structure component from high-strength steel AISI 4340 under cycling mode I loading in hydrogenating environment using the developed model. It is possible to improve the Paris-Erdogan constants, which are correct for inert environment, using the author's results for hydrogen-contain environment. The new constants will be correct for the considered environment-material pair.