A novel iron enrichment isothermal kinetic model proposal for galvanneal coatings

Galvanneal (GA) coatings are extensively used in the automotive industry in car bodies and for exposed parts to enhance corrosion protection. GA coatings are produced in Continuous Galvanizing Lines (CGL) by carrying out a heat treatment immediately after the Zn deposition in the liquid state, where the liquid is constitutionally solidified and transformed into Fe–Zn alloy (composed by its intermetallic compounds (IMCs)). IMCs nucleation and growth kinetics control allows one optimize the coating mechanical performance during steel drawing operations. This work proposes a new kinetic model to describe the GA coating Fe enrichment. Based on the hypothesis that each IMC will be nucleated, Fe enriched, saturated and consumed by an Fe richer IMC, the model was able to describe the Gleeble simulated isothermal Fe enrichment kinetics for unalloyed industrially produced interstitial free (IF) and dual-phase (DP) GA coating steels.