Speakers
Description
In order to improve fuel efficiency and to reduce carbon emissions, automakers are using advanced high strength steels (AHSS) to lightweight vehicles without compromising passenger safety. In manufacturing, the steel sheet is annealed in a continuous galvanizing line (CGL) to achieve the desired mechanical properties. During annealing, alloying elements such as Si, Mn, Cr, Al, etc. in the steel can form oxides, which pose coatability challenges. Knowing the morphology and the type of these oxides can help pinpoint the defect source and improve AHSS coatability. The present work was conducted to determine the oxide phases formed as a result of annealing temperature and annealing furnace atmosphere. The annealed steel surface was evaluated using various surface analytical techniques. The oxide type and coverage were predicted by combining GDOES chemical depth profile with thermodynamic calculations using the Gibbs Energy Minimization (GEM) principle.
Keywords
Surface Oxide, Gibbs Energy Minimization, Annealing, AHSS