Properties of Tool Steels for Application in Hot Stamping

Hot stamped high‐strength steel components for car bodies become increasingly important due to the need to save weight for multiple reasons such as fuel conservation regulations. Tribological systems in tools for hot stamping depend on process parameters and may include, e.g., mechanical and thermal loads as well as adhesive and abrasive wear. Furthermore, the process cycle time should be as short as possible due to economic reasons. Commonly used hot work tool steels mainly suffer from rather low wear resistance, whereas in terms of process cycle time, a high thermal conductivity is desired. Thus, solutions showing optimized combination of key properties for application in hot stamping such as wear resistance, high thermal conductivity, toughness, and hardening behavior need to be found. In this contribution, novel high thermal conductivity hot work tool steels, especially designed for application in hot stamping, are presented and some key properties are compared, e.g., to those of conventional hot work tool steels like 1.2367, which is commonly used in this application. Furthermore, tribological investigations are performed in laboratory tests according to ASTM G65 and G75 as well as a flat strip‐drawing test setup using sheets of 22MnB5 under hot stamping conditions.