After a metal has been heated and quenched, it should be reheated in a process called tempering, or drawing, to relieve the stresses caused by the previous steps. Quenching leaves metals stressed, too brittle and hard for use. Tempering relieves the stresses, increasing the toughness and ductility of the metal while retaining sufficient hardness and strength.
During this final stage of heat treatment, the metal is heated again, this time to a temperature below the critical range. Different degrees of hardness can be developed in the steel by utilizing different drawing temperatures. The higher the drawing temperature, the softer the steel becomes. Double tempering is a wise precaution that Knights highly recommends.
Knights Dragon Fire Furnace features an improved heavy duty guillotine door with seals. The door lifts and lowers easily. The programmable control is simple to operate with minimal steps. An alarm or signal light alerts users when the cycle is complete. The furnace can also use inert gas, for use with air hardening steel, providing a clean, decarb-free heat treated part.