<p>Tempcore is an intensive quenching and tempering process for rebars to improve their mechanical properties. A preliminary study should be conducted prior to mass production to anticipate the quenching effect. The temperature after rebar quenching was estimated by determining the correlation between input variables and manufacturing outputs through multiple data analyses. The inputs are considered a diverse set of manufacturing variables, not a single value, as Tempcore is a process controlled thermo-mechanically and metallurgically. The principles of heat transfer were employed to introduce heat loss in Tempcore. Martensite formation was computed numerically using the estimated heat transfer coefficient and other key parameters obtained from data analysis. The evaluation was carried out by measuring the depth of tempered martensite, and the prediction was well agreed with the experimental test results.</p>