MS-4-P-3305 simultaneous determination of carbon concentration and misorientation angle in bainitic ferrite laths via convergent beam electron diffraction

In this reserach, the carbon content of multiple bainitic laths are determined via accurate convergent beam electron diffraction method (CBED). The misorientation angles betweeen bainitc ferrite laths can also be determined simultaneously. A 0.1C-3Mn-2Si steel was used in this research, and carbide-free bainite was formed, which is currently widely studied due to potential mechanical behaviour as a result of TRansformation Induced Plasticity effect (TRIP). For the first time, misorientation angles between and carbon content in bainitic laths are gathered at the same time, allowing more clear understanding of the characteristics of bainite transformation. Misorientation angles are identified using Kikuchi lines and simulating software, while the carbon concentration was deduced CBED high order Laue zone (HOLZ) lines shift due to lattice parameter expansion.  It was found out that the misorientation angles between the adjacent bainitic ferrite laths generally has two type, either KS-variants related or in very small angle. The prior one is due to variant selection during austenite to bainite transformation, while the latter one is possibly due to plastic accomodation of austenite after the formation of previous bainitic ferrite. The carbon concentration of each lath was also individually determined, and results are in accord with previous researches using atom probe tomography (ATP), suggesting the reliability of CBED method. Simultaneous morphological, crystallographical and chemical informations can be obtained using CBED method.