The contribution of grain boundary dislocations to the plastic deformation of nanostructured titanium from the SD-effect of the yield stress

The deformation curves in uniaxial tension and compression at 300 K were studied for commercial grade Ti and for ultrafine-grained Ti with different nanostructures produced by severe plastic deformation through equal channel angular pressing (ECAP) and subsequent thermal treatment. It is found that differences between the yield stresses in tension and compression (SD-effect) depend on the structural states of Ti and on the texture of the samples. The SD-effect value differs considerably for samples strained along directions parallel and perpendicular to the ECAP axis. The influence of the texture upon the yield stress under uniaxial compression has been studied at 300, 77, and 4.2 K.