Shibata, M., Oonishi, M., Makino, K., and Kurach, S., "Method of Improving Side Impact Protection Performance by Induction Hardening of Body Reinforcement Compatibility Between Safety and Weight Reduction in Body Engineering," SAE Technical Paper 980550, 1998, https://doi.org/10.4271/980550.
A technique for induction-hardening local portions of vehicle body reinforcements press-formed of thin sheet steel has been developed, with the aim of ensuring occupant safety in a side collision. This technique for increasing the tensile strength of sheet steel was practically applied to the front floor cross member and center pillar reinforcement. Owing to this method, the weight of body reinforcements can be decreased. New induction-hardening systems have also been developed for the present technique. One is an apparatus which allows induction-hardening a part with a three-dimensionally curved surface. Another is a straightening quench technique used to retain the same dimensional accuracy as the original press-formed part.