焼入試片の中心部冷却曲線の一般化  [in Japanese] Unification on Cooling Curves of Quenched Bars at Center  [in Japanese]

Cooling curve of a specimen quenched into a still coolant varies with not only the cooling behaviour of coolant but also other factors such as dimension, shape and material of specimen. An examination was made to show the influence of these factors on cooling curves and the following expression was proposed. t=k{(D.W/S)^nL・a^<-n>M} Values of N_L and N_M were determined experimentally by using the many cooling curves obtained from various sorts of coolants, and N_L and N_M were evaluated 1.31 and 0.215 respectively. Unification of the cooling curve was made by conversion of cooling time to t/{(D・W/S)^nL・a^<-n>M} for each shape, dimension and material. whree, t : cooling time of the central portion of a specimen during quenching, W/S : ratio of volume to surface area of a specimen for the unit size, a : thermal diffusivity, n_L, n_M : experimental constants.