Micromechanical aspects of hydrogen degradation in high-strength structural steels

Abstract

We analyze micromechanical aspects of hydrogen degradation in high-strength structural eutectoid steels under the conditions of various triaxial stress states and hydrogen embrittlement generated by cathodic charging. Hydrogen causes microdamage in the form of different microscopic modes of fracture associated with different stages of the process of hydrogen degradation so that the evolution of hydrogen-assisted microdamage strongly depends on macroscopic variables such as the triaxiality of stresses in the critical region. We show that the zone microscopically affected by hydrogen can be modeled as a macroscopic crack growing in the subcritical model until final fracture, which is an unstable process.