Influence Of Hydrogen Environment On Crack Growth Rate

Hydrogen as an energy carrier and hydrogen applications, as fuel cells, are considered to play an important role in energy storage. The study of the mechanical characteristic of steels under the influence of hydrogen embrittlement is an essential area due to the importance of these materials for mechanical system like fuel cells and huge infrastructure like pipeline and vessels. Metallic materials, such as carbon and low alloy steels, may suffer hydrogen damage and hydrogen embrittlement. A model to predict the hydrogen embrittlement crack growth rate in the II region of the da/dN-ΔK plot is suggested. This model will predict the behaviour of the material as a function of the experimental parameters such as: test temperature, load frequency and ΔK. In particular, once it is known the material behaviour without hydrogen and how hydrogen enhances embrittlement, it is possible to predict the crack growth rate and therefore the crack length after a certain number of cycles, at constant load, for a certain temperature and load frequency. This model rests on a superposition of effects: mechanical fatigue crack growth and purely hydrogen embrittled sustained growth.