High-pressure gas quenching

Advances in gas quenching have been needed to keep pace with the expanding requirements of vacuum furnaces, including larger parts, higher production rates, and the processing of materials that must be rapidly cooled, such as hardenable stainless steels, tool and die steels, and oil-hardening alloy steels. The ability to quench at high gas pressures is a case in point. As oil and salt quenching increasingly become the target of safety and environmental regulations, the capabilities and economics of gas quenching above 6 bar will attract a growing number of heat treaters. In the not-too-distant future, pressures of 10 to 20 bar will be routinely used. Of even more potential importance is the application of heat-transfer fundamentals to controlling distortion in gas-quenched parts. The techniques being developed use directed gas flows to enhance cooling uniformity. Interest also is growing in gas quenching in multichamber vacuum systems. For a given pressure, quenching in a separate chamber can increase productivity and part hardness. Multichamber systems and directed gas flows also can be used for directional, selective, or partial hardening of parts, such as a soft-shank drill.