Microstructural Evolution of a Hot-Stamped Boron Steel Automotive Part and Its Influence on Corrosion Properties and Tempering Behavior

Boron-manganese steel 22MnB5 is extensively used in structural automotive components. Knowledge about its microstructural evolution during hot stamping and resistance spot welding (RSW) extremely relevant to guarantee compliance with application requirements. Particularly, corrosion properties are critical the of uncoated sheet steels. However, studies usually simplified top-hat geometries, which might not be fully representative complex thermomechanical cycles locally faced by a real component. Therefore, present work brings an extensive characterization hot-stamped B-pillar terms microstructure, hardness resistance, were correlated reverse engineering process using numerical simulation. Physical simulations subcritical heat affected zone (SCHAZ) RSW done assess influence microstructure on martensite tempering. Results showed that component undergoes strain distribution along body stamping. Most heavily strained regions presented higher amounts ferrite, leading poorer since ferrite behaves as anode. SCHAZ softening degree due tempering solely peak temperature, while other features appear exert negligible or no influence.