INFLUENCES OF GASEOUS ENVIRONMENT ON LOW GROWTH-RATE FATIGUE CRACK PROPAGATION IN STEELS

Lower strength steels have traditionally been considered to be immune to embrittlement in the presence of hydrogen gas. In this work, it is demonstrated that contrary to conventional wisdom, there are two regions of fatigue crack growth where hydrogen gas causes significant accelerations in crack propagation rates compared to air. Environmental influences in these two regimes are shown to be dominated by entirely different mechanisms.