Hydrogen‐induced stress corrosion cracking studied by the novel tuning‐fork test method

Abstract A novel tuning‐fork test method was developed to study hydrogen‐induced stress corrosion cracking of high‐strength steels. Special tuning‐fork specimens are designed to enable accurate stress adjustment via constant displacement under cathodic hydrogen charging conditions. In this study, the testing method is further developed, making the potentiostatic hydrogen charging possible through the modifications of the corrosion cell. Different direct‐quenched, low‐ and medium‐carbon steel grades, with a hardness range of 300–550 HBW, are investigated with both galvanostatic and potentiostatic hydrogen charging techniques. For each steel grade, the lowest fracture stress and highest no‐fracture stress are determined. Both hydrogen charging techniques produce similar results, and it is observed that the fracture stress decreases with the increase in hardness. However, the potentiostatic technique produces larger differences between the lowest fracture stress results, thus having a better resolution