EFFECT OF DEFORMATION CONDITIONS ON

CONTINUOUS COOLING TRANSFORMATION

OF WEATHERING STEEL WITH Mn-Cu

WU Hongyan¹  DU Linxiu¹  LIU Xianghua¹  WANG Guodong¹  DONG Junhua²  DONG Jie³

(1. State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110004;
2. Environmental Corrosion Center, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110004;
3. Technology Center, Lai Gang Group Co. Ltd., Laiwu 271104)

Abstract: The continuous cooling transformation (CCT) curves of austenite non-deformation and compressively deformed for a weathering steel are constructed by means of a dilatometry in combination with metallography measurement by MMS-100 thermomechanical simulator, and the microstructure evolution of the steel is analyzed and compared. Optical microscope, scanning electronic microscope (SEM) and transmission electronic micro-scope (TEM) are employed to investigate the influence of cooling rate, deformation process on the transformation behavior and microstructure. Experimental results show that the deformation promotes the area of polygonal ferrite and pearlite to move to-wards top left corner, leading to the increase of critical cooling rate obtained ferrite plus pearlite. With cooling rate increasing, the grains refine and the tensile strength increases. The deformation on austenite stifles the growth of bainitic ferrite by tangled dislocations resulting the refinement of microstructure. Lath-like microstructure observed at the cooling rate ranging from 20~ 30 ℃/s is mainly revealed to consist of bainitic-ferrite with cementite. Granular microstructure observed at the cooling rate ranging from 5~10 ℃/s is characterized to be martensite-austenite constituent islands or pseudopearlite in matrix.

Key words: Weathering steel Continuons cooling transformation curves Austenite deformation Retained austenite Transmission electronic microscope (TEM)

CLC No: TG115.21

国家二期重点基础研究发展计划资助项目(973计划, 2004CB619101). Received 20060711, received in revised form 20070416