3.10. Correlation between experimental cooling curves and Continuous
Cooling Transformation diagrams – CCT
The cooling curves obtained experimentally for the Jominy test
were confronted with CCT diagrams in order to predict the possible
formed microstructures during the test. Figs. 21–23 show the cooling
curves superimposed on a CCT diagram for AISI 1045 steel [20].
For the three austenitizing temperatures, it was observed that is
possible during the continuous cooling to obtain different
structures. At position TP1 when the temperature decreases as a
function of time the thermal curve crosses only the region of
martensite formation. At position TP2 it is formed a certain amount
of bainite and martensite. In the TP3 and TP4 positions, there is the
formation of ferrite, pearlite, bainite, and the martensite is
formed in smaller amounts, as explained in Fig. 13. Finally, at the
TP5 and TP6 positions, with lower cooling rates, only occurs the formation of ferrite and pearlite for this type of steel. Çakir et al.
[10] and Trzaska et al. [21] demonstrated that the use of
thermocouples for the cooling curves is efficient. The CCT curves
are an excellent graphical tool to compare the curves with the
microstructure resulting from experimental or simulated trial,
according to [20].