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High Si bainitic steel has received much interest because of combined ultra high strength, good ductility along with high wear resistance. In this study, the microstructural evolution of dual phase bainitic ferrite-austenite steel after heavy compression was investigated. Compression tests were conducted at temperature of 298K on the rectangular billets at the strain rate of 0.001s-1. The samples were deformed to 40% and 70% of their original thickness. The EBSD results show formation of nano grains with high angle grain boundaries through 70% compression, which confirms grain refinement. Additionally, 40% deformation resulted in enhancement of the dislocation density and formation of subgrains at ferrite unites. Also, it was found during 70% compression of the steel, the austenite transforms to the martensite, which is in agreement with thermodynamic calculations.

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Microstructure and mechanical properties of high Si bainitic steel, before and after two passes of equal channel angular pressing (ECAP) at room temperature were investigated. SEM and TEM microscopy were used for microstructural study. Shear punch test and Vickers hardness test of as received and ECAPed samples were carried out to measure the influence of ECAP process on the mechanical properties of the samples. The results showed that tensile strength and shear strain were increased as a consequence of ECAP processing.