Speaker
Description
The demand for hydrogen resistant materials is increasing due to planned usage of hydrogen as energy according to European Union’s AFIR – Alternative Fuels Infrastructure Regulation. The infrastructure needed for storing and transporting hydrogen requires vast amounts of materials withstanding embrittlement and other failures caused by hydrogen. Austenitic stainless steels with their face-centered cubic (FCC) crystal structure are known for their excellent resistance against hydrogen embrittlement. However, stainless steels generally have moderate strength, and their extensive usage is relatively expensive. Carbon steels would offer cost-friendly solution with improved strength, but their body-centered cubic (BCC) crystal structure is prone for hydrogen embrittlement.
The beneficial properties of the two steels can be potentially combined by joining them together by hot-rolling. The thermomechanical process to produce reliably bonded multilayer steel was developed in our study. The microstructure of the interface region was studied using up-to-date characterization methods. The steel was charged with hydrogen, and the mechanical properties were tested by tensile testing with and without hydrogen. A multi-physics numerical model using phase field method to predict hydrogen embrittlement was developed and validated against the experimental results.
The results showed that the stainless steel, specifically AISI 316L, layer acted as a diffusion barrier protecting the carbon steel and provided improved toughness and excellent resistance against hydrogen embrittlement, whereas carbon steel layer provided increased strength making the developed multilayer steel a potential candidate as a material needed for hydrogen-carrying infrastructure.