Conference Papers

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Author: search.filters.author.Pranesh Rao, K.M.Has files: No

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    Assessment of wetting kinematics and cooling performance of select vegetable oils and mineral-vegetable oil blend quench media
    (Trans Tech Publications Ltd ttp@transtec.ch, 2015) Pranesh Rao, K.M.; Prabhu, K.
    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.
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    Wetting kinetics and cooling performance of PAG polymer quenchants
    (Trans Tech Publications Ltd ttp@transtec.ch, 2015) Pai, A.; Nayak, U.; Pranesh Rao, K.M.; Prabhu, K.
    The present research work is aimed at the estimation of quench severity Polyalkylene Glycol (PAG) polymer quenchants having varying concentrations. An Inconel600 probe instrumented with thermocouples was used for this purpose. The thermal history at various locations in the probe was used as an input to the inverse heat conduction model. The inverse analysis yields spatially dependent heat flux transients. The quench severity was assessed using the Grossmann technique. The wetting kinematics of quenching was studied by cooling curve analysis. The severity of quenching as measured by the Grossmann’s technique was found to be higher for polymer quenchants. However, the heat flux transients estimated by the inverse technique and rewetting times measured form the cooling curve analysis suggested comparable and uniform heat transfer with polymer quenchants compared to water quenchants. © (2015) Trans Tech Publications, Switzerland.