November 20, 2008
Gas quenching follows the final thermal soak in vacuum. The furnace is quickly backfilled with inert gas to atmospheric or positive pressure and the gas, driven by a powerful fan or blower and continuously recirculated, flow at high velocity over the workload and through a gas-to-water heat exchanger. The inert gases used for gas quenching are nitrogen, argon, and helium. Quench rates are enhanced through the use of cooling gas at greater than atmospheric pressures. The advantage of higher pressure cooling is a denser gas, with increased mass flow and therefore greater thermal conductivity, all of which add up to improved cooling rates. In addition, gas blowers and heat exchangers operate at better efficiency at increased pressure.
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