Influence of Temperature and Tempering Conditions on Thermal Conductivity of Hot Work Tool Steels for Hot Stamping Applications

The knowledge of thermal conductivity is essential for improving and designing tools for hot working applications like hot stamping and high-pressure aluminum die casting. This study investigates the influence of alloying composition and heat treatment on thermal conductivity of two different hot work tool steels in the temperature range between 20 and 500 °C. Thermal conductivity was determined with an indirect measurement by using the dynamic method. The thermal conductivity of the two tool steels was found to be dependent on the amount of alloying elements, heat treatment condition, and operating temperature. In the regime of hot stamping applications, i.e for service temperatures below 200°C, thermal conductivity increases with temperature for both steels irrespective of their heat treatment condition. In applications in which tools are subjected to temperatures above 200°C (such as high-pressure die casting operations), thermal conductivity of the steels decreases as tool temperature increases.