Assessment of axial and radial heat transfer during immersion quenching of Inconel 600 probe

The time-temperature data at axial and radial locations were measured during immersion quenching of Inconel 600 probe in a mineral oil quench medium. The cooling of probe was not uniform during quenching. The variation of cooling rate along the axial direction was found to be higher than around the radial location. Inverse heat conduction problem (IHCP) was solved for estimating heat flux transients from the temperature data and thermo-physical properties of the Inconel probe. Single and multiple unknown heat fluxes were assigned on the metal/quenchant boundary. The error between the estimated and measured temperatures reduced significantly with increase in number of unknown surface heat flux components. The peak heat flux was about 50% lower for assignment of single unknown heat flux compared to multiple unknown heat fluxes at the metal/quenchant boundary. A plot of isotherms indicated gradual and uniform cooling of the quench probe when single heat flux boundary was used. With increase in the number of heat flux components, non-uniform and large temperature variations in the quench probe were observed. The present work outlines the importance of estimation of spatially dependent boundary heat flux transients during quench heat treatment.