Partial strengthening method for cold stamped B-pillar with minimal shape change

The partial strengthening method for pre-stamped panels both avoids excessive strength enhancement over the entire product and substantially reduces the processing cost compared to conventional hot press forming. In this paper, we propose two types of partial strengthening processes to selectively increase the local strength of a cold stamped B-pillar by utilizing an induction coil system and water spray quenching to induce the martensitic transformation in the target region. Thermo-mechanical FE analyses were conducted to evaluate the effect of the process parameters such as the quenching rate, quenching time, and heating width on the shape changes during the partial strengthening processes while simultaneously considering the thermal dilatation and transformation plasticity.