Effects of Niobium on Phase Transformation and Lameller Spacing of Pearlites of High Carbon Steel during Continuous Cooling

Effect of niobium on phase transformation and lamellar spacing of pearlites of high carbon steels during continuous cooling was studied on Gleeble 1500 thermo-mechanical simulator and microscopes.The results show that adding 0.04wt% niobium to high carbon steels made CCT curves significantly move to the lower right and pearlite transformation temperature decrease.Niobium element had a double effect on nucleation growth rate of pearlite,which made average nucleation growth rate of pearlite kept constant and little changes of the interval width of transition temperature after adding niobium.Niobium could increase undercooling of high carbon steel,which could reduce lamellar spacing of pearlites.