Quenching oil for quenching under reduced pressure and quenching method

摘要

A quenching oil for quenching under reduced pressure, which comprises a base oil having a kinematic viscosity at 40 ° C of 40 mm 2 / s or more and a vapor blanket breaking agent; and a quenching method in which the quenching oil is used and the quenching is performed while adjusting the pressure on the surface of the oil are provided. The process allows cooling properties to be achieved over a wide range of those achieved by a cold oil to those achieved by a warm oil by using a single quench oil.