To achieve HRC 60-62, temper DC53 twice at 540° C (1,005° F) for 60 to 90 minutes per inch in thickness in cross section. The minimum tempering time is 90 minutes. Temper twice at 520° C (970° F) for the same amount of time to achieve HRC 62-64. A hardness les than HRC 60 is not generally recommended for most punch and die components due to insufficient compressive strength typically needed for stamping applications. Applications requiring additional toughness can be double tempered at 550° C (1,020° F) to achieve HRC 58-60.

If size change or distortion of hardened DC53 due machining, grinding, applying surface treatments or wire EDM work is a concern in high precision applications, an optional third temper of 400° C (750° F) can be applied to the initial heat treat process. This final tempering temperature is high enough to temper the remaining un-tempered martensite, but not high enough to convert additional retained austenite resulting in a more stable structure. The third temper is typically not necessary if the tool has been hardened using the salt bath process.

Inspection – Conducting a hardness test after the heat treat process is complete is just one method used to measure the quality of heat treat. For additional quality assurance, it is also recommended that a precise dimensional measurement be taken from a given feature both before and after the entire heat treat process to assure that the proper amount of growth has taken place. Properly heat treated DC53 can be expected to grow approximately .1% to .1 ½% (.001” to .0015” per inch) of its original size before hardening. Shrinkage of the tooling can be a sign of problems in the hardening and or tempering process and is generally attributed to excessive amounts of retained austenite.

Vacuum Tempering – As when tempering most tool steels, vacuum tempering is a more difficult process to control than convection tempering and fluctuations in hardness results are to be expected. It should only be used when absolutely necessary and ideally be limited to smaller parts with a simple geometry.

Cryogenics – Freezing at 185° C (-300° F) between the first and second temper may also be beneficial to toughness however, specific data is not readily available. It is important to note that cryogenics should always be followed by a temper.

Forging – For special applications, DC53 can also be forged into many shapes. The temperature for forging is between 900° C (1,650° F) and 1,100° C (2,010° F). Annealing after forging in highly recommended to minimize stress in the part and assuring