Resistance Rapid Heating of Aluminum Coatings in an Extreme High Vacuum–Adequate Atmosphere for Hot Stamping

Hot stamping also known as press hardening is one of the most important processes for manufacturing components with strengths exceeding 1500 MPa. The process combines heat treatment and forming in a single operation. Heating is typically carried out in gas‐fired roller hearth furnaces and, due to the AlSi coating, requires slow heating times of 6–10 min. For alternative heating methods such as resistance heating, only uncoated sheet material can be used. However, during rapid heating rates of more than 100 K/s, the sheets suffer from scaling, which makes costly postprocessing necessary. This study demonstrates that by using a protective atmosphere of nitrogen and monosilane, a process environment can be created that corresponds to the oxygen concentration of an extreme high vacuum. At the same time, this process atmosphere enables the in‐situ coating of uncoated sheets with the process heat required for hot stamping. Furthermore, it is shown that coating materials can be applied which form intermetallic phases.