New Method for Deriving Functional Relations, Illustrated on the Example of the Temperature Dependence of Impact Toughness.

Using 92 test specimens of nodular graphite cast iron and malleable cast iron, ductile-brittle transition temperatures and their relation to other properties of these materials were investigated by scatter field analysis and simple regressions. Especially favorable and reliable mathematical functions were obtained by an iteration process even when only a few values were available. As an approximation for the transition temperature, the temperature for half the impact toughness at the high level continues to seem more accurate than the temperature of the turning point in the transition curve. It is suggested that the rate of the temperature decrease be reported in addition to the transition temperature.