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 deforma-tion 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: Continuons cooling transformation curves, Austenite deformation, Retained austenite, Transmission electronic microscope (TEM), Weathering steel