EBSD Investigation on Effect of Cooling Rate on Microstructure and Transformation Textures of High Strength Hot-rolled Steel Plates

The effect of cooling rate on the microstructure and transformation textures of high strength hot-rolled steels was investigated.Heat treated samples subjected to different cooling conditions were characterized by optical and scanning electron microscopes using orientation imaging microscopy(OIM).The experimental results demonstrate that there is a significant effect of cooling rate on microstructures and textures resulting from phase transformation.Slow cooling rates lead to the appearance of the cube(001)[010],rotated cube(001)[110]/(001)[110],Goss(110)[001]and rotated Goss(110)[110]components.In contrast,textures developed at rapid cooling rates are preferably of Cu(112)[111],Br(110)[112],transformed Cu(113)[110]and transformed Br(332)[113]/(112)[131].These texture changes are attributed to the selective character of the phase transformation.The OIM technique was used to have a better understanding of the formation of phases and their relationship between microstructure and processing conditions.The volume fraction of micro-constituents resulting from phase transformation such as bainite,martensite and different types of ferrite,can be measured satisfactorily by this technique correlating image quality of EBSD patterns to specific phases.