Microstructural evolution and formation mechanism of bimodal structure of 0.2% carbon steel subjected to the heavy-reduction controlled rolling process

A heavy-reduction controlled rolling process with approximately 75% thickness reduction was carried out to investigate the microstructural evolution including texture development, focusing on the formation of a bimodal structure of 0.2% carbon steel with heating temperatures of 700, 800, 900, and 1000 degree C. Upon increasing the heating temperature from 700 to 900 degree C, the microstructure was refined and precipitates such as Fe3C were uniformly distributed throughout the microstructure. For the microstructures control-rolled at heating temperatures of 900 and 1000 degree C with average ferrite grain sizes of 1.34 and 1.63 mu m, respectively, a bimodal structure could be observed by scanning electron microscopy (SEM), which was very similar to the result of a plane-strain compression (PSC) test. Moreover, the 900 and 1000 degree C-heated specimens had less well developed textures primarily consisting of {113}-{4 4 11}110 and {332}113 components, which usually developed by the transformation ( gamma arrow right alpha ), and the 1000 degree C-heated specimen exhibited various textures and a low intensity of the {100}011 component, which was generally transformed from the {100}001 component of the recrystallized austenite.