Faculty Publications
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Item Comparison of Grossmann and lumped heat capacitance methods for assessment of heat transfer characteristics of quench media(2011) Prabhu, K.N.; Ali, I.The suitability of Grossmann and lumped heat capacitance (LHC) methods for estimation of quench severity of nanofluids, brine solutions and a laboratory detergent based medium was investigated. The study involved the assessment of the effect of section thickness of the probe on heat transfer coefficients for different quench media. Computer aided cooling curve analysis during quenching of type 304 stainless steel probes was carried out. The measured thermal history data were used to estimate heat transfer coefficients by Grossmann and LHC methods. The LHC method based on a 10 mm diameter stainless steel probe was found to be applicable for characterising media having quench severity less than 20 m-1. Although Grossmann method is based on the concept of average heat transfer coefficient, it can be used for quench media having varying severity of quenching. Grossmann method is found to be more sensitive to the effect of section thickness on heat transfer. © 2011 IHTSE Partnership.Item Critical Heat Transfer Coefficients for Selection of Quench Media during Heat Treatment of Steels(Springer, 2025) Samuel, A.; Pranesh Rao, K.M.; Prabhu, K.N.The depth of hardness in during quench hardening of steels depends on the steel composition, section thickness, and the boundary heat transfer coefficient. A simulation study is performed in the present work to optimize the heat transfer coefficients for selecting quenchants for a particular grade of steel and section thickness. The simulation study is performed by solving phase transformation coupled transient heat conduction equation using the finite element method. The finite element model adopted in this work uses the one-dimensional radially symmetric model with a constant heat transfer coefficient boundary condition at the surface. The variables in the simulation study are the carbon content, the diameter of steel, and the heat transfer coefficients. The effect of these variables on the martensite formation is studied. A critical heat transfer coefficient is defined corresponding to a 50 pct. martensite transformation at the core of the steel cylindrical specimens. The critical heat transfer coefficient increased with the increase in the diameter; whereas, it showed a parabolic relation with the carbon content. The usefulness of the study in selecting a suitable quenchant for quench hardening of plain carbon steels with varying carbon content is illustrated. © ASM International 2024.