Acicular Ferrite Microstructure of A Low-carbon Mn-Mo-Nb Microalloyed Pipe Steel

摘要

The transformations during cooling processes, the effects of hot deformation and the morphology of the final microstructure of a low carbon Mn-Mo-Nb microalloyed pipe steel designed for Acicular ferrite microstructure was investigated. The results show that there are three independent "C" curves of isothermal phase transformation, i.e., TTT diagram, of low-carbon microalloyed steel, namely, polygonal ferrites/pearlite "C" curve, the massive ferrite "C" curve and the Bainitic "C" curve, respectively. The hot deformation accelerates the Acicular ferrite transformation and refines the steel's matrix. The microstructure of Acicular ferrite was discussed.