JFE Steel’s Wall Bending and Restrike Method Selected for Production of Vital Structure Part Supplied to Major Automakers in Japan

13 June 2024

JFE Steel Corporation announced today that its Wall Bending and Restrike method has been selected by Japanese auto parts maker Kyoho Machine Works, Ltd. to suppress springback, or a part returning to its original shape, when pressing 1180MPa-grade ultra-high-strength steel. The company will use JFE Steel’s proprietary method to produce rocker inners, a key structural component used in vehicles manufactured and sold in Japan by major automakers.

JFE Steel’s new method is a long-sought solution for suppressing springback when press-forming ultra-high-strength steel. Springback can be minimized by reducing the residual stress in steel sheet during press forming, or by applying a counter-stress to offset stress that causes springback. The Wall Bending and Restrike method optimizes the shape of the steel in the beginning of the multi-stage press-forming process and applies stress to suppress springback.

Kyoho Machine Works will deploy the forming method in a new die it will use to mass-produce rocker inners (photo), a key structural component located at the bottom of a vehicle doorway. JFE Steel and Kyoho Machine Works jointly developed the die, which is specially designed for use with the Wall Bending and Restrike method.

JFE Steel supplies ultra-high-strength steel sheet used by automakers to produce lightweight vehicles that achieve superior fuel efficiency and thus reduce CO2 emissions. When high-strength steel sheet is press-formed, the pressed part tends to return, or spring back, to its original shape when removed from the press tool. Ultra-high-strength steel is subject to greater springback than ordinary steel sheet because higher stress must be applied during press forming. Springback can cause a part to deviate from its intended shape specifications.

JFE Steel provides customers not only with steel products, but also with solutions that they can use to develop and upgrade their own products. JFE Steel actively pursues early vendor involvement (EVI) with automakers to collaborate from the early stages of vehicle development. The company offers a wide range of applied technologies in a comprehensive, systematized solution called JESOLVA® (JFE Excellent Solution for Vehicle Application), which includes proprietary technologies for automotive steel sheet.

Going forward, JFE Steel will continue to expand opportunities for the use of ultra-high-strength steel in automotive parts to improve vehicle performance and reduce weight, ultimately for a more sustainable world