Texture Analysis In Commercially Pure Titanum After Equal Channel Angular Pressing At Room Temperature

Equal Channel Angular Pressing (ECAP) is one of the main techniques to refiningCP-Ti microstructure and improving the mechanical properties such as strength viasevere pure sheardeformation. In the present paper, commercial purity titanium (Grade1)was successfullyprocessed via route C to four passes at room temperature. During thefourth pass, the average size of HAGB grains of CP Ti is refined down to170nm.Scanning electron microscope (SEM) and Electron backscattered diffraction (EBSD)are employed to investigate the microstructure and texture of commercial purity Ti afterECAP. Grain orientation, grain boundaries, grain size and twinning of everydeformation pass were analyzed with EBSD Channel5software. The texture evolutionof CP-Ti during multi-pass ECAP and the effect of texture on mechanical properties anddeformation mechanism were investigated by pole figures and ODF.The results show that the during the first pass, the texture seems to be just simplyrotated around the TD axis in the positive rotation direction by70°. During the secondpass, the texture consists mainly of the nearly initial texture and the weak deformationtexture. During the fourth pass, the maxima reach the B fibre position, which representsnormal to shear plane.Based on the experimental results from both EBSD and TEM observation, thegrain refinement process can be explained as continuous dynamic recrystallisation.Theevolution mechanism. First, dislocation tangle zones are formed near the HAGBs, andthen dislocation cell blocks are formed by the local recovery of dislocation tangle zonesand band structure, where the dislocation density is high enough. Second, with morelattice rotation of dislocation cell blocks, subgrains can develop from the increasingmisorienta tion between neighbouring dislocation cell blocks. Finally, LAGBs gradually evolve into HAGBs for the increasing misorientation. Ultrafine grain structure wasachieved.