焼入試片の冷却曲線の導出方法  [in Japanese] Method to Derive Cooling Curve of Specimen During Quenching  [in Japanese]

A cooling curve whose scale of the abscissa is transformed to t/{(D-W/S)^<1.3>・a^<-0.215>} was proposed as a master cooling curve of the coolant used, where t is cooling time of a quenched bar D, W, and S are dimension, weight, and surface area of the bar, respectively, and a is thermal diffusivity. W/S is taken for a unit size bar similar to the quenched one. The curves for various coolants were obtained. A calculated cooling curve of a bar quenched into a still coolant was compered with the measured one of the same bar and in the same coolant, and they coincided well with each other. The method to derive the master cooling curve could be applied for any quenching temperature. A cooling curve of a quenched bar at any inside position could also be infered by using the curve at the center.