Proceedings of the Third International Conference on Metals & Hydrogen A04

Hydrogen-assisted low-cycle fatigue of advanced high strength steels

Nicholas Winzer (1)1 , Richard Thiessen (1)1 , Roland Sebald (1)1 , Hans Peter Schmitz (1)1

  • (1) 1

    Thyssenkrupp Steel Europe, Kaiser-Wilhelm-Straße 100, 47166 Duisburg, Germany


A widely held view is that the susceptibility of steels to H-assisted degradation increases with tensile strength. Whilst this may be an oversimplification, it illustrates the need to address H-assisted degradation in the development of advanced high strength steel (AHSS) grades, some of which havetensile strengths greater than 1000 MPa. Such steels are increasingly in demand, due to the need to reduce the weight of automobiles without increasing cost. Consequently, there is a need to develop a deeper understanding of the mechanisms for H-assisted degradation of AHSS grades, as well as testing methods for characterising their susceptibility to H-assisted degradation under conditions that can be related to production and service. In this study, a method for evaluating the resistance of AHSS grades to H-assisted fatigue was developed. Tests were performed using a slow strain rate tensile (SSRT) testing apparatus at a frequency of 0.01 Hz with and without in-situ H charging. Benchmark tests were performed on non-charged samples in a servo-hydraulic fatigue testing apparatus at frequencies from 0.05 to 30 Hz. The fatigue life of the non-charged samples tested using the SSRT apparatus was shorter than those tested using the servo-hydraulic apparatus, although it was unclear whether this was due to the intrinsic frequency dependence of the material or the resolution of the apparatus. The method was applied to two dual-phase steels with tensile strength of around 1000 MPa, which differed in their Ti content and yield strength. The reduction in fatigue life due to H charging of the material with higher Ti concentration was greater than that for the material with lower Ti concentration. This is consistent with the negative influence of Ti(C,N) particles on the susceptibility to H-assisted fatigue, but may have also been affected by the material’s yield strength.


  • advanced high strength steel
  • hydrogen-assisted low-cycle fatigue