Study on the Fog-Quenching Method

Abstract

The fog-quenching is very profitable for quenching of cast or forged steel pieces, because it can control the cooling rate in a wide range, and make uniform cooling at various sections of a material with complicated shape by controlling the flow rates of water and compressed air. We studied the effect of the flow rates of water and compressed air and the distance between the nozzle and the quenched end of a test piece on the uniformity of fogquenching and the quenching ability, by using experimental fog-quenching apparatuses. The results obtained were as follows.
The uniformity of quenching could be improved by decreasing the flow rate of water or by increasing that of compressed air, but greatly improved by increasing the distance between nozzle and quenched end, though, in both cases, the quenching ability decreased.
With an increase in the flow rates of water and compressed air, the quenching ability increased remarkably at first, but saturated gradually.
From the severity of quench factor (h-value) calculated from experimental data by using E. Schmidts'diagram, it was found that the fog-quenching method could cover a wide range of cooling rates from that of oil quenching to that of air cooling.