The development of new high-strength steels is an important topic at ThyssenKrupp Steel. Application of these new steel grades in automotive production can support significant weight reduction in order to achieve future CO2 targets. However, it is necessary to consider certain requirements of these new steels in order to achieve cost-optimized cold forming and operations such as flanging and punching. The focus of this paper is to present current trials to validate new high-strength steel grades based on practical press shop experience over the past few years.
One particular sensitivity of multiphase steels is the hole expansion and shear fracture behavior of cutting edges. Different cutting parameters, such as the clearance and radii of the cutting edges, are analyzed in laboratory tests. Furthermore, the hemming and flanging performance of high-strength steels is validated using a new testing tool. To identify optimization potential for the low-cost cutting of high-strength steels, hole punching wear tests on inclined surfaces were carried out. As a result, the burr height up to 100,000 strokes was observed for different cutting angles and steels grades. It was possible to hole-punch high-strength material at angles up to 15°.
