Study on Microstructures and Continuous Cooling Transformation Behavior of LowCarbon Microalloyed Pipeline Steel
LIU Shouxian1,2,LUO Haiwen1,WANG Ruizhen1,LONG Jinming2
1.Institute for Structural Materials, Central Iron and Steel Research Institute，Beijing 100081, China; 2.Faculty of Materials and Metallurgical Engineering, Kunming University of Science and Technology， Kunming 650093,Yunnan, China；
Abstract：Static (without deformation) and dynamic (after deformation in the nonrecrystallized austenitic region)curves of continuous cooling transformation were measured by the highresolution dilatometer attached to the thermomechanical simulator Gleeble3800 at the various cooling rates. Microstructures after different cooling rates were characterized by optical microscope and electronic microscope. The microstructures in samples change from polygonal ferrite, pearlite, acicular ferrite, granular bainite to lower bainite with the increasing microhardness when cooling rate increases. It is found that deformation in the nonrecrystallized region can shift Ccurve to the left side, expand the range of formation of acicular ferrite and lead to finer microstructures in samples.
