Effect of Controlled Rolling and Cooling Parameters on Structure of Niobium Microalloyed Steel

Utilizing Gleeble-1500 thermomechanical simulator,the microstructure under the conditions of different controlling rolling and cooling parameters was investigated.The deformation induced ferrite was induced when deformed at low temperatures,and pearlite transformation was promoted obviously.The pearlite lath reduced when temperature and cooling rate increased.Bainite transformation region was inlarged when deformed at high temperatures.Bainite transformation was retarded at low temperaturs because of the occurence of deformation induced ferrite transformation.