On the Formation of a Non-Traditional Pearlite Morphology
Continuous cooling and isothermal dilatometry was performed for a binary Fe-0.3C alloy and a ternary Fe-0.3C-1.0Mn alloy at slow (< 0.1 oC/s) cooling rates and isothermally at temperatures below the equilibrium eutectoid reaction temperature but above the bainite start temperature (625 to 715 oC). Some of the test conditions produced an unusual morphology in which fine scale ‘sub-grains’ are decorated with carbide, with additional discrete carbide particles inside the ‘sub-grains’. A detailed investigation into the network carbide formation indicates formation during austenite decomposition, as opposed to a post lamellar transformation coarsening or spheroidization reaction, but only for select temperatures, and apparently only during isothermal conditions.
T. Chandra, K. Tsuzaki, M. Militzer , C. Ravindran
E. B. Damm et al., "On the Formation of a Non-Traditional Pearlite Morphology", Materials Science Forum, Vols. 539-543, pp. 4544-4549, 2007