The influence of hydrogen on the mechanical and fracture properties of some martensitic advanced high strength steels studied using the linearly increasing stress test

The influence of hydrogen on the mechanical and fracture properties of four martensitic advanced high strength steels was studied using the linearly increasing stress test and electrochemical hydrogen charging. The hydrogen influence increased with steel strength, decreasing charging potential, and decreasing applied stress rate. Increased hydrogen influence was manifest in (i) the decreased yield stress attributed to solid solution softening by hydrogen and (ii) the reduced macroscopic ductility, and by the change from ductile cup-and-cone fracture to macroscopically brittle shear fracture, attributed to a dynamic interaction of hydrogen with the dislocation substructure somewhat similar to the HELP mechanism.