ABSTRACT
Generally, hot metals are quenched by liquids, by immersing the hot metals into a liquid bath, or by spraying the hot metal with a l iquid. These three quenching techniques are shown in Figure 6.1. Independent of the type of quenching, a stable vapor lm forms over the hot surface which exhibits an insulating effect so that cooling during this lm boiling process is relatively low. The vapor lm collapses when the temperature of the surface falls below the Leidenfrost temperature. Figure 2.1 shows that in subsequent ranges of partial lm boiling and nucleate boiling, a con siderably larger heat ow is transferred allowing the metal to cool rapidly. Heat loss during lm boiling and the in uence on the Leidenfrost temperature are dependent on the quenching process.
