thermo-couple into the melted weld pool behind the arc. A typical temperature-time curve is shown in Figure 3.11. this curve, which is typical of all arc welding studies, results from the common situation in which a high local temperature is reduced by the conduction of heat to the relatively extensive surrounding cold base metal.
As shown in figure 3.12, a linear relationship exists between the cooling rate at 1000°F (538°C) and the average cooling rate between 1472°F and 932°F (800°C and 500°C)
The relationship between the weld cross-sectional area and the cooling rate, show in Figure 3.13, is con-sistent whether the cooling rate is measured at 1000°F (538°C) or 1300°F (704°C)