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Mechanical properties of steel workpiece are often evaluated based on its hardness. For quenched and tempered steels, hardness can be predicted based on quenching and tempering processing parameters. For that reason, prediction of tempered hardness of steel based on its quenched hardness is of big interest. This work establishes a new mathematical relation for prediction of hardness after tempering of quenched steel. This relation is based on relationship given by E. Just. According to E. Just, the hardness after tempering of quenched steel can be predicted by taking into account the temperature of tempering and the degree of hardening, where degree of hardening is quotient of achieved and theoretically possible hardness which is used as measure for hardenability of steel. Improvement of this relationship can be done by considering the chemical composition of steel. Different chemical elements have different diffusivity and different influence on tempering kinetics of steel. Influence of the chemical composition of steel on hardness after tempering is taken into account by the carbon equivalent (CE). Example of application of established relation was given in computer simulation of tempering of quenched steel workpiece, where the hardness of quenched steel workpiece was predicted based on the characteristic cooling time from 800 °C to 500 °C.
Keywords: Mathematical modeling, hardness, quenched and tempered steels© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.