Examples of Fractured Steel Parts during Actual Usage due to Hydrogen Embrittlement and Consideration Regarding the Behavior of Hydrogen at the Prior Austenite Grain Boundary

Steel parts fractured during actual use were investigated, and the mechanism of fracture for some of them was attributed to hydrogen embrittlement. This article describes a summary of the observation results fractured by hydrogen embrittlement. Fracture occurred under tensile stress within the elastic limit including residual stress. Most of the parts had a martensitic microstructure, and intergranular fracture surfaces were always observed in martensitic steels at least on part of the fracture surface. This observation indicates the importance of the role of hydrogen on the prior austenite grain boundary in hydrogen embrittlement.