Mathematical modelling of hardness of quenched and tempered steel

Purpose: In this paper a new mathematical model and expressions for prediction of hardness of quenched and tempered steel was established. Design/methodology/approach: Novel mathematical expression for prediction of hardness of quenched and tempered steel was established. This expression includes tempering temperature, hardenability properties and degree of hardening. By experimental work it was found out that results of quenching and tempering are related to hardenability properties of steel. Findings: Based on experimental work it was found out that prediction of hardness of quenched and tempered steel is more precise by novel mathematical expression than by relation according to the German standard DIN 17021, or than by relation established by Just, E. Research limitations/implications: By taking into account the hardenability properties of steels, influence of diffusivity on kinetic of tempering processes is indirectly taken into account in the mathematical modeling of tempering processes without using the chemical composition of steel. Practical implications: The established relations were applied in mathematical modeling and computer simulation of quenching and tempering of shaft made of low alloyed steel. It was found out that hardness of quenched and tempered steel workpieces can be successfully calculated by the proposed method. Originality/value Hardenability properties of steel are included in the established relation to achieve more precise prediction of quenched and tempered steel hardness. The influence of diffusivity on kinetic of tempering processes is indirectly taken into account in the mathematical modeling of tempering processes without using the chemical composition of steel. Keywords: Steel ; Quenching and Tempering ; Hardness ; Computer Simulation