Microstructures and Mechanical Properties of X100 Pipeline Steel Strip Original Research Article

Dynamic CCT (continuous cooling transformation) curves and effects of microstructures and M/A islands of X100 hot rolled strip on mechanical properties were studied by means of a thermal simulator, a scanning electron microscope (SEM), a transmission electron microscope (TEM), a digital micro-hardness tester and Image-Pro Plus analysis software. The results show that high contents of C and Mo can make transformation lines of acicular ferrite and bainite shift rightward. High Mo tested strip has higher strength and micro-hardness and lower toughness than the other one because lath bainite appears instead of quasi-polygonal ferrite. Tested strip with granular bainite, lath bainite and M/A islands has better mechanical properties and in the microstructures lath bainite content is around 36.5% and M/A islands are fine and disperse in the matrix.