Abstract: The evolution of degenerate ferrite in an Fe-0.28wt-3.0wtMo alloy isothermally reacted for 10ks at 20℃ below TTT diagram by temperature have been revealed utilizing serial sectioning in conjunction with computer reconstruction and visualization.The degenerate ferrite is initially formed at prior austenite boundary and then grows toward grain interior rather than along the grain boundary.The degenerate morphology of ferrite may be attributed to repeated nucleation,growth and coalescence of adjacent ferrite crystals.The shape of individual ferrite crystals oppears to be rod-like.

Key words: steel, phase transformation, microstructure,