Electrochemically plated ultra-high strength steels (UHSS) are martensitic steels of high strength with yield limits beyond 1400 MPa. Zn-Ni coatings offer excellent corrosion resistance, as they allow the formation of complex corrosion products that stop the diffusion of corrosive species. The hydrogen in the steel lowers its load bearing and energy absorption ability, and this negative effect on the steel's properties is termed as hydrogen embrittlement (HE). HE causes delayed cracking, which might lead to catastrophic material failures.

The prevalent disadvantage of using ultra-high strength martensitic steels is their susceptibility to HE. Herein, a finite element model is developed to capture the transport of hydrogen in plated UHSS during hydrogen embrittlement relief treatment (degassing). Naturally, the morphology of the plating plays an important role in the degassing efficiency and the grain structures, grain boundaries, trapping sites and residual stresses dictate the diffusion of hydrogen in the steel. Thus, microstructural images are analysed to understand the microstructure, distribution of the phases and grain structure of the UHSS and the plating, and are subsequently utilized to create the geometry of the model. The underlying equations account for the surface reactions leading to the release, reflection back into the steel lattice and inflow due to the difference in partial pressure of hydrogen across the surface. The computational model is calibrated using experimental data for 300M steel with different plating morphologies, and finally a workflow is established to determine the concentration of hydrogen in a part after hydrogen embrittlement relief treatment.