Assessment of wetting kinematics and cooling performance of select vegetable oils and mineral-vegetable oil blend quench media

Abstract

Quench hardening is a process where an alloy is heated to solutionizing temperature and held for a definite period, and then rapidly cooled in a quenching medium. Selection of quenchant that can yield desired properties is essential as it governs heat extraction process during quenching. In the present work, the cooling performance of vegetable oil and mineral-vegetable oil blend quench media was assessed. The vegetable oils used in this work were olive oil, canola oil and rice bran oil. The mineral-vegetable oil blends were prepared by blending 10 and 20 vol. % of rice bran and canola oil in mineral oil. Inconel probe of 12.5mm diameter and 60mm height, instrumented with thermocouples were used to characterize quenchants. The probe was heated to 850�C and quenched in the oil medium. The cooling curves at different locations in the probe were used to study wetting kinematics. Inverse modelling technique was used to estimate spatially dependent metal-quenchant interfacial heat flux. It was found that the vegetable oils exhibited very short vapour blanket stage compared to mineral oil and blends. Faster wetting kinematics obtained with blends resulted in uniform heat transfer compared to that of mineral oil. The temperature distribution in the probe quenched in vegetable oils and blends was more uniform compared to that in mineral oil. It is expected that the parts quenched in vegetable oils and blends would lead to better hardness distribution compared to mineral oils. � (2015) Trans Tech Publications, Switzerland.