Effects of Potentiostatic Polarization during Slow Strain Rate Testing (SSRT) in Natural Seawater on the Fracture Behavior of High Strength Steel

In the present study, a high strength steel for offshore wind turbine tower substructure was submitted to tensile load using slow strain rate technique to evaluate fracture characteristics of the steel with application of electrochemical potentials ranging from free corrosion potential to -1.2 V in natural seawater.The results of the study revealed that the fracture characteristics of the steel changed drastically with different applied potentials.The failure time ratio was 0.5 or less in the potential range of -1.0 V to -1.20 V due to hydrogen evolution.The fractured surface after the slow strain rate test indicated that the brittle fracture tendency was prevalent in the potential region corresponding to the hydrogen embrittlement.It is concluded that cathodic overprotection exceeding -1.2 V may lead to brittle fracture of the offshore steel structure.