Quench oil selection principle

quenching oil is almost all mineral oil with high flash point. the specific heat capacity of these oils is about 1/2 of tap water, the thermal conductivity is about 1/4 of tap water, the convection starting temperature is high, and the viscosity is much higher than that of water, so that the cooling rate of quenching oil, especially in the low temperature stage, is much lower than that of water. For this reason, most workpieces are quenched in oil (including various fast oils) without the risk of quenching and cracking, and there is a general concern that the cooling rate of the oil is low, so that thicker workpieces or steels with slightly lower hardenability cannot reach the required quenching hardness and hardening depth, and therefore large deformation occurs.

For this reason, when selecting quenching oil, it is usually only considered from the minimum cooling rate distribution curve of various workpieces.

only when the cooling rate distribution curve of the selected quenching oil can surround the lowest temperature cooling rate curves of these pieces from the right, in general, the shorter the vapor film stage of the selected oil, the lower the convection start temperature, and the greater the maximum cooling rate, the more the cooling rate curve of such oil may surround the minimum cooling rate distribution curve from the right, I .e. the more applicable workpieces (steel grades). This is suitable for a variety of workpiece quenching oil selection principle.