Study on Deformation Induced Ferrite Transformation in Mild Steels with or without Niobium
Two mild steels with Nb-microalloying and Nb-free were smelted. After single-pass hot compression of various processes conducted on a Gleeble-2000 thermomechanical simulator, the effects of deformation conditions and Nb-microalloying on microstructural evolution kinetics, including the volume fraction, grain size and grain number per unit area were investigated through quantitative metallographic analysis. The experimental results show that, grain number per unit area of DIF increases with decreasing deformation temperature or increasing deformation amount; the grain size of DIF is not very sensitive to the deformation conditions; the volume fraction of DIF increases due to the increased grain number per unit area. The microalloying element of Nb dissolved in austenite inhibits the grain growth and reduces the volume fraction of DIF.
Jitai NIU, Zuyan LIU, Cheng JIN and Guangtao Zhou
L. J. Wang et al., "Study on Deformation Induced Ferrite Transformation in Mild Steels with or without Niobium", Materials Science Forum, Vols. 575-578, pp. 898-903, 2008