Alloying Strategies for Secondary Hardening in High‐Boron Cold Work Tool Steels: A Comparative Study

Post processing of tool steels often requires an elevated tempering resistance, enabled by the precipitation of tempering carbides, increasing the hardness. This necessitates sufficient solute contents of alloying elements in a supersaturated iron matrix after austenitizing and quenching. Both, carbide‐forming refractory elements (i.e., tungsten, molybdenum, or vanadium) as well as elements like manganese or silicon influence the tempering carbide precipitation. This study investigates the influence of the alloying elements tungsten, vanadium, silicon, and manganese on the tempering behavior of boride rich high boron cold work tool steels (HBTS). Thus, alloys with varying compositions and element contents are cast, swaged, and heat treated. The hardness after tempering at different temperatures is measured. Microstructural investigations by electron microscopy and atom probe tomography (APT) are performed to contextualize the findings. It is found that tungsten influences the tempering hardness negligibly, whereas vanadium significantly enhances secondary hardness. APT analysis reveals the precipitation of VC tempering carbides. Silicon and manganese, both individually and in combination, increase the tempering hardness. These insights pave the way for the adaptation and utilization of HBTS in future applications that necessitate high tempering resistance due to postprocessing or elevated operating temperatures.