Abstract
The author investigated the effects of viscosity and vaporisation of several quenching media on cooling velocity. The results are as follows: (1) The relation between the mean cooling velocity (v) and the coefficient of viscosity (η) of oils is given by the equation v=a log1/η+b, in the range of temperature from 20°C to 100°C. Where a and b are constants which depend upon the characteristics of medium. (2) The addition of small amounts (less than about 1 per cent.) of water to oil, makes the stepped changes in cooling curve abnormaly, and retards the cooling velocities at relatively high temperatures, on account of the fact that the vaporisation of water contained in oil occurs during quenching.
