Application of significance tests in quantitative metallographic analysis of a C–Mn–B steel

Microstructural analysis of a C–Mn–B steel was done using a mean chord measurement method on flat sections of metallographic specimens. The morphological changes of microstructure for assumed cooling rates in the range 0.05 K s− 1 ≤ V8–5 ≤ 12 K s− 1 were investigated. Comparison of the mean chords of ferrite and pearlite grains, for selected cooling rates, was done using samples received from wire rod ∅ = 5.5 mm or cooled in a dilatometer.The significance tests: λ Kolmogorow, Kolmogorow-Smirnow, F Snedecor and of two means values were used for proving the identity of wire rod and the microstructures of the dilatometric samples for particular cooling rates.The microstructures of the ∅ = 5.5 mm wire rod consisted of ferrite and pearlite with a small amount of Widmanstätten ferrite and bainite, after an initial cooling to the temperature 1073 K and further cooling in air, which corresponded with the cooling rates in the range 0.25 K s− 1 < V8–5 ≤ 2.32 K s− 1. A correlation equation is presented.