Novel Roll-Bonded Stainless Steel/Boron-Steel Multilayer Under Hot Stamping Conditions

Aluminum-silicon-coated (AlSi-) boron-steels are regarded as standard material in direct hot stamping processes. Nevertheless, the material brings along some disadvantages such as the requirement of a long dwell time in the furnace for the generation of a resistant diffusion layer. In this paper, a multilayer steel sheet with a boron-steel core-layer and stainless steel outer-layers is introduced and the manufacturing process by hot roll-bonding is described. Due to the stainless steel surfaces, a coating for hot stamping is no longer necessary. The multilayer is characterized by hot tensile tests and compared with the monolithic multilayer-partners. Hot stamping experiments are conducted on a laboratory scale. Corresponding hardness measurements show that the core-layer is hardened while the outer-layers remain ductile. The new multilayer sheets offer the potential to deliver components with higher formability due to tailored properties along the sheet thickness and the use of rapid heating methods.