Comparative study of neem and mineral oils for quench hardening of steels

The cooling behavior of neem and mineral oils were obtained using thermocouples instrumented ISO 9950 inconel probe. Flash and fire points and the viscosity of quenching media were measured using a Cleveland open cup apparatus and Brookfield Rheometer respectively. These oils were used to quench harden AISI1045 and AISI 52100 grade steel probes of section diameters 25 and 50 mm. The end faces of steel probes were coated with insulating paste to minimize end effects of heat transfer during quenching. The measured temperature data in the steel probes were used to estimate spatiotemporal heat flux by inverse heat conduction technique to assess the heat flow at the interface of the probe/quenching medium.The estimated heat flux transients, microstructure, and hardness measurements were found to be similar for both oils which indicate the potential of neem oil to substitute mineral oil as quenchant for heat treatment of steels.