A synchrotron X-ray and electron backscatter diffraction based investigation on deformation and failure micro-mechanisms of monotonic and cyclic loading in titanium

Materials science and engineering / A 726, 143 - 153 (2018). doi:10.1016/j.msea.2018.04.036
Synchrotron X-ray diffraction technique has been used to estimate defect structure in terms of dislocationdensity, crystallite size and micro-strain in commercially pure titanium subjected to tension and cyclic deformationin stress and strain control mode. Statistical analysis of micro-texture data collected from electronbackscatter diffraction approximately from the same region as that of synchrotron X-ray has been used to correlateorientation dependent micro-strain and dislocation density with deformation microstructure and microtexture.Two different orientations, namely, A with prismatic-pyramidal and B with basal orientation along theloading axis has been considered. Weak initial texture yet significant anisotropy in hardening/softening responseand failure mode for monotonic tension and cyclic loading paths has been observed. Higher strain hardeningresponse of orientation A during monotonic tensile deformation can be attributed to the evolution of lowermicro-strain on basal orientation grains i.e, 〈0002〉ǁND along with extensive multi-variant twinning that alsorestricts crack propagation and delays failure in stress control mode. On the other hand, in strain control mode,orientation B shows higher fatigue life due to the generation of lower micro-strain in the basal orientation grainsand single variant twinning that can undergo detwinning easily is responsible for delayed crack nucleation andsubsequent failure.
Published by Elsevier, Amsterdam