A Theory of Critical Distances based methodology for the analysis of environmentally assisted cracking in steels

This paper provides a methodology, based on the Theory of Critical Distances (TCD), for the hydrogen embrittlement analysis of steels in cracked and notched conditions. The TCD has been successfully employed in fracture and fatigue analysis, but it has not yet been applied under environmentally assisted cracking conditions. The point method and the line method, both belonging to the TCD, have been applied to two steels (X80 and S420) following an experimental programme composed of C(T) specimens containing defects with notch radii varying from 0 mm up to 2 mm. Fracture mechanics tests were carried out at 6.10(-8) m/s of constant displacement rate under cathodic polarization conditions (5 mA/cm(2)). The aqueous environment has been prepared following the Pressouyre's method. The study, which has been completed with finite element simulation analysis, reveals that the TCD provides accurate predictions of the hydrogen embrittlement behaviour of these steels in notched conditions.