Gas quenching system and method for minimizing distortion of heat treated parts

A method of quenching a hot metal part composed of a specific metal or metal alloy capable of having an austenite phase, a martensite phase, and inherent metal properties of a first specific heat and a first thermal conductivity in the austenite phase and a second specific heat and a second thermal conductivity in the martensite phase, comprising the steps of:

• A. selecting a first point located at, or about, a slowest cooling point of the hot metal part and a second point located at, or about, a fastest cooling point the hot metal part, and
• B. quenching the hot metal part with the requirement that a temperature difference exists between the first point and the second point, said temperature difference being between about 5° C. and about 30° C. during a quench cycle which starts from a first time when the second point about 5° C. above a martensite start temperature of the specific metal or metal alloy and ends at a second time when the first point at a temperature which is about, or below, a martensite finish temperature of the specific metal or metal alloy.