Assessment of Cooling Performance of Neem Oil for Distortion Control in Heat Treatment of Steel
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JMEPEG https://doi.org/10.1007/s11665-020-05082-4
Assessment of Cooling Performance of Neem Oil for Distortion Control in Heat Treatment of Steel K.M. Pranesh Rao and K. Narayan Prabhu (Submitted March 28, 2020; in revised form July 20, 2020) Growing concerns over the hazardous impact of mineral oil-based industrial quench media on human health and the environment have forced researchers to seek renewable and non-hazardous alternatives. Non-edible vegetable oil-based quench media are perceived to be a potential replacement for mineral-based industrial quench media. The present work focuses on assessing the cooling performance of neem oil as compared to commercial hot oil quench media. Inconel and steel probes were used to characterize the cooling performance of these quench media maintained at bath temperatures 100 °C, 150 °C and 200 °C. The heat extraction rates and uniformity of heat extraction in Inconel probes quenched in neem oil were observed to be substantially higher at all bath temperatures. The hardness of AISI 52100 steel probe quenched in neem oil at all bath temperatures was observed to be higher. The pearlitic microstructure was observed in the steel probe quenched in hot oil maintained at 200 °C bath temperature. In contrast to this, a mixture of bainite, martensite and carbide was observed in case of steel probes quenched in neem oil maintained at 200 °C. Oxidation experiments revealed that neem oil is susceptible to an increase in viscosity due to oxidation. An increase in the viscosity by about 15% was observed in the case of neem oil as compared to only 4% increase in viscosity of hot oil. However, after an initial increase, the viscosity of neem oil stabilized and further no significant change in viscosity due to oxidation were observed. Oxidation had no significant effect on the cooling performance hot neem oil quench medium, and thus, it can be considered as an effective replacement for hot oil. Keywords
bio quenchants, heat treatment, inverse heat transfer, oxidation, steel
1. Introduction Oil quench media are the most common quenchants used in the heat-treating industry (Ref 1). Mineral oil possesses several environmental problems and fire risks; nevertheless, 85% of heat-treating industries use these quench media (Ref 2). The petroleum-based quench oils can be broadly classified into four types, namely normal-speed quench oils, medium-speed quench oils, high-speed quench oils and marquenching oils or hot oils (Ref 3). Normal-, medium- and high-speed oils are used to quench harden steel parts of different grades and section sizes. The operating temperature does not exceed 50 C. These oils contain paraffinic and naphthenic fractions. Antioxidants, accelerators and emulsifiers are added to the base oil to improve the service life of the oil, enhance cooling performance and ease post quench cleaning of steel parts, respectively (Ref 4). Martempering oils are formulated from refined paraffinic base oils with high thermal stability. Carefully selected and tested antioxidants are added to retard the a
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