Proceedings of the Third International Conference on Metals & Hydrogen P13

The impact of diffusible hydrogen on the formability of Galvannealed DP980 steel

Dongwei Fan (1)1 , Naveen Ramisetti (1)1

  • (1) 1

    ArcelorMittal Global R&D 3001 E. Columbus Drive, East Chicago, IN 46312, USA


Formability is one of the most critical properties of Advanced High Strength Steel for automotive applications. In the present study, the formability of galvannealed dual phase steel with 980MPa tensile strength was evaluated by conducting 90-degree V-bend test and hole expansion test. Fractography study indicated that the bend failure was associated with the interaction between inclusions and diffusible hydrogen (Hdiff) in the steel. The drop of hole expansion ratio after 48 hours delay was also related to diffusible hydrogen in the steel. By removing the diffusible hydrogen via heat treatment, both bendability and hole expansion ratio was improved. However, the tensile properties of the steel were changed after the heat treatment. In addition to experimental results on diffusible hydrogen and its impact on bendability and hole expansion, this paper also discussed implications on forming practices in stamping plants for AHSS grades with TS greater than 980MPa.


  • Formability
  • Bend
  • Hole expansion
  • Inclusion
  • Hydrogen