Abstract: Quenching oil based on the mineral oil results in a heavy pollution due to being hard to be degraded. Surveys show that the mineral oil harms most to the ground water resource, and the use and the discharge of mineral oil are in- creasingly strictly controlled. Thus it is necessary to develop the replacement for mineral oil, A new quench oil based on the rapeseed oil is introduced. It is proved that the new quenching oil has great environmental advantages and good cooling characteristics as well, and is a hopeful substitute for prevailing quenching oil based on mineral oil.

Key words: Environment protection Mineral oil, Vegetable oil, Quenching oil