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

摘要

Microstructural analysis of a C-Mn-B steel was done using a mean chord measurement method on flat sections of me-tallographic specimens. The morphological changes of microstructure for assumed cooling rates in the range 0.05 Ks~(-1) < = V_(8-5) < = 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 PHE=5.5mm or cooled in a dilatometer. The significance tests: lambda Kolmogorow, Kolmogorow-Smirnow, F Snedecor and of two means values were used for proving the identity of wire rod and the microstmctures of the dilatometric samples for particular cooling rates. The microstractures of the PHI = 5.5 mm wire rod consisted of ferrite and pearlite with a small amount of Widmanstatten 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) < = V_(8-5) < = 2.32 K s~(-1). A correlation equation is presented.