Influence of External Factors on the Cooling Ability of Vacuum Quenching Oils

Abstract

This paper presents research on vacuum quenching oils at different pressure conditions during the cooling stage of the heat treatment process. The aim of this work is to reveal the influence of the pressure, agitation (laminar or turbulent flow), and oil temperature on the cooling oil. Medium and low viscosity oils are investigated. The research is novel because it expands knowledge of quenching oil behavior at low and high pressure conditions (from 1 mbar to 2.5·103 mbars). The findings are presented as integral diagrams (time-temperature and cooling rate versus temperature curves) and tables of the local cooling ability valuations. It is found that the pressure in the chamber is the main factor that influences the cooling ability of the examined media. The trend of pressure influence can be generalised as: the greater the cooling oil ability, the stronger the pressure value influence. In addition to the above, the possibility of routine change of the pressure makes it a prospective factor to control the cooling oil ability.

Effects of vacuum oil quenching on distortion of 42CrMo Navy C-ring

“…The cooling process primarily consists of three stages: film boiling, nucleate boiling, and convective heat transfer [10]. Gospodinov et al [11] demonstrated that the cooling ability of vacuum quenching oil is affected by the chamber pressure, agitation, and oil temperature. However, Troell et al [12] reported that the cooling characteristic does not significantly vary for the given pressure (0.4–1.4 bar) above the oil tank, and decreased quenching distortion is only observed at a higher pressure.…”