Post-forming Heat Treatment of Dual Phase Steel Components for Automotive Applications Using a Fluid Bed Furnace

A result of the increased usage of advanced high strength steels (AHSS) for stamped automotive body structures is an increase in press forces and tool wear, as well as component geometrical issues, such as springback and curl. This study investigates a methodology of forming a dual-phase steel component in a ‘softened’, or annealed, condition, then subsequently heat-treating and quenching the component using a fluid bed furnace into a final ‘hardened’ state. Channel sections were formed to show that the ‘softened’ steel exhibits significantly lower press forces and springback than the as-received material. Post-forming heat treatments on the channel sections and tensile samples show that the hardened microstructure and properties can be regained, and oxidation minimised using a controlled atmosphere in the fluid bed furnace. It is also shown that quench distortion is dependent on the orientation of the channel section, and can potentially be controlled.