Printed and heat-treated 1.2379 tool steel is equivalent in hardness to heat-treated 1.2379 forged steel with the same post-processing. 1.2379 tool steel can be heat-treated to increase hardness and durability. Markforged recommends heat-treating 1.2379 tool steel to optimize material properties, although it can also be used in the as-sintered state. Heat a 1.2379 tool steel part in a standard (non-vacuum) furnace to 1000°C (1830°F). Hold the part at this temperature for 30-45 minutes. Quench the part in air to below 65°C (150°F). Harden the 1.2379 tool steel part in a standard furnace. For each tempering process, heat the part to 200°C (392°F) and temper for 30 minutes. If double tempering, allow the part to cool to room temperature between temperings.