where T0 is the initial temperature (470 oC); Td is the temperature at location d when the quenched surface temperature reaches 100 oC, and t is the corresponding time. Fig. 7 shows the average cooling
rate (v) at different distances from the quenched surface of the sam-
ples (point P2 and P3, as shown in Fig. 1) with different flux densi- ties and spraying pressures. These curves show some similar variations: when the flux density keeps unchanged, the cooling rate increases with the increasing spraying pressure; when the spraying pressure keeps unchanged, the cooling rate increases with the increasing flux density.