Critical fracture strength of the martensite structures for the hydrogen embrittlement

Kaburaki, Hideo; Tsuzaki, Kaneaki*

A tensile test has been performed for the martensite steel sepecimen charged with hydrogen. The results show that intergranular fracture was observed in the region when the hydrogen concentration is high. Stress and hydrogen distribution near the notch of the specimen are predicted by the finite element method using the continuum model. In order to find the cause of this fracture, a change in the cohesive strength of a simple grain boundary due to hydrogen segregation is estimated by the first principles calculation. As a result, a relative reduction of the critical applied stress for the hydrogen embrittlement test is explained well by the results of the first priciples calculation.