Proceedings of the Third International Conference on Metals & Hydrogen D03

Interpretation of the hydrogen effect on the static and dynamic tensile behaviour of dual phase steel

T. Depover (1)1 , F. Vercruysse (2)2 , A. Elmahdy (2)2 , P. Verleysen (2)2 , K. Verbeken (1)1

  • (1) 1

    Department of Materials, Textiles and Chemical Engineering, Ghent University (UGent), Technologiepark 903, B-9052 Ghent, Belgium

  • (2) 2

    Department of Electrical Energy, Metals, Mechanical Constructions & Systems, Ghent University (UGent), Technologiepark 903, B‑9052 Zwijnaarde, Belgium


Present work considers the hydrogen (H) induced mechanical degradation in a dual phase steel by performing tensile tests under static and dynamic conditions. Tensile specimens were electrochemically H pre-charged until saturation and tensile tests were subsequently executed ex-situ. The applied current density was modified to induce different H contents into the samples. The impact of H diffusivity during the tensile tests on the hydrogen embrittlement (HE) susceptibility was evaluated by increasing the strain rate from static (1.67*10-2 and 1.67 s-1) to dynamic (450 and 900 s-1) conditions. Additionally, the experiments allow assessing the possibly detrimental effect of the combination of dynamic loading and H on the mechanical response of DP steel. Therefore, a reproducible methodology was established to deliver reliable and innovative data. A standardized tensile machine was used for static testing while split Hopkinson bar experiments were performed for dynamic conditions. The HE resistance decreased when current density increased for all strain rates due to higher H amounts in the sample, as confirmed by melt extraction. The HE% increased when slower strain rates were applied since H was able to diffuse to a crack tip and hence accelerate failure. Even at the highest strain rate (900 s-1), the material lost about 10% of its ductility. However, this observation was related with H in the material and not with H diffusion during testing. This was concluded since H induced brittle failure initiated at the edges of the samples at slow strain rates. Though at a strain rate of 1.67 s-1, fracture initiated in a ductile way from the center similarly as tests performed without pre-charging. Fractography on fracture surfaces revealed a brittle central line when charged with H, which evolved into a major crack. EDX analysis showed MnS inclusions were present in this central line, affecting H induced crack initiation.


  • hydrogen embrittlement
  • hydrogen diffusivity
  • static and dynamic tensile testing
  • Hopkinson
  • dual phase steel.