The steels of different carbon content were tested with respect to their microstructural and selected mechanical parameters variations. The original combinatorial method, based on the phase quanta theory, was applied in the quantitative metallographic assessment. Hence, the adequate geometrical parameters of steel microstructure were possible to be determined. Moreover, the selected mechanical parameters of the materials were evaluated using non-destructive and destructive methods. The results enabled to formulate some significant quantitative relationships between microstructure and mechanical parameters.