Fundamental Technologies for Hydrogen Embrittlement Assessment of Steel Materials

Abstract

Hydrogen embrittlement is caused by a small amount of hydrogen in steels used under applied stress, which is a critical issue in the current era when there are growing needs to further increase the strength of steels used for instance for bolts, automotive parts, and to use steels under higher hydrogen pressure for utilizing hydrogen energy. It is desirable to establish appropriate methods to evaluate hydrogen embrittlement properties of various types of steels quantitatively for safe and secure usage of materials. Several types of evaluation methods based on stress and hydrogen concentration have been utilized so far. In this review, some evaluation methods for high strength steels using such as constant load test, slow strain rate test, conventional strain rate test, and tests using U-bend specimens and stretch-formed specimens, are explained briefly. In addition, recently developed hydrogen visualization techniques using an Ir complex and polyaniline for understanding hydrogen uptake and diffusion are introduced.