Heuristic Design of Advanced Martensitic Steels That Are Highly Resistant to Hydrogen Embrittlement by ε-Carbide

Many advanced steels are based on tempered martensitic microstructures. Their mechanical strength is characterized by fine sub-grain structures with a high density of free dislocations and metallic carbides and/or nitrides. However, the strength for practical use has been limited mostly to below 1400 MPa, owing to delayed fractures that are caused by hydrogen. A literature survey suggests that epsilon-carbide in the tempered martensite is effective for strengthening. A preliminary experimental survey of the hydrogen absorption and hydrogen embrittlement of a tempered martensitic steel with epsilon-carbide precipitates suggested that the proper use of carbides in steels can promote a high resistance to hydrogen embrittlement. Based on the surveys, martensitic steels that are highly resistant to hydrogen embrittlement and that have high strength and toughness are proposed. The heuristic design of the steels includes alloying elements necessary to stabilize the epsilon-carbide and procedures to introduce inoculants for the controlled nucleation of epsilon-carbide.

Automated summary

Research shows that ε-carbide in tempered martensite is effective for strengthening steels and promoting resistance to hydrogen embrittlement. By incorporating alloying elements and controlled nucleation of carbides, martensitic steels with high strength, toughness, and resistance to hydrogen embrittlement can be designed.