Browsing by Author "Khadar Syed, Abdul"
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Item Open Access An in situ study on the role of heterogeneous microstructure on anisotropic tensile deformation behaviour in an additive manufactured Ti6Al4V alloy: Data(Cranfield University, 2024-04-03 10:27) Khadar Syed, AbdulAdditive manufacturing (AM) processes are known to produce heterogeneous microstructures and thereby, anisotropic mechanical properties. However, a fundamental understanding of the anisotropic mechanical behaviour of AM-built Ti6Al4V is limited, particularly for high-deposition-rate wire-feed directed-energy-deposition AM processes. The present study provides insights into the role of heterogenous microstructure and associated texture on the tensile deformation and damage accumulation in wire-feed directed-energy-deposition Ti6Al4V. Materials were deposited using oscillation-pass and parallel-pass build strategies. In situ neutron diffraction studies were performed on samples with tensile loading applied parallel and perpendicular to the built layers. Dissimilar thermal histories experienced in the parallel-pass strategy resulted in thinner columnar β grains and finer transformation microstructure, resulting in higher yield strength compared to the oscillation strategy. The presence of strong columnar β fibre texture in both build strategies led to anisotropic deformation. When loaded perpendicular to the columnar grains, elastic strain accumulation is more crystallographically homogeneous and includes basal, prismatic, and pyramidal plane strain accumulation in both build strategies. Conversely, when loaded parallel to the columnar β fibre texture, the majority of the pyramidal orientations preferentially aligned along the loading axis and were subjected to significant elastic strains. Similar anisotropy was observed under plastic deformation where tensile strain accumulation observed in the prismatic planes and prismatic slip is found to be the major slip activity. Such activity was not detected when loaded parallel to the columnar grains. Hence anisotropic deformation is observed in the studied material.Item Open Access Data supporting: 'Strain controlled fatigue behaviour of wire + arc additive manufactured Ti-6Al-4V'(Cranfield University, 2023-03-07 19:02) Khadar Syed, Abdul; Williams, StewartThis paper investigates the strain controlled fatigue and cyclic deformation behaviour of a wire + arc additive manufactured Ti-6Al-4V alloy in the as-built condition. Higher local heat input used to build the material exhibited a coarser parent columnar β grain structure along with a coarser transformation microstructure compared to other additive manufactured Ti-6Al-4V. Test specimens were manufactured in horizontal and vertical orientations with respect to the deposited layers. Property isotropy was observed at lower applied strain values. When the strain amplitude was above 0.6%, the vertical samples, where the loading axis was in parallel with the parent columnar β grains, showed marginally higher fatigue strength owing to larger plastic deformation. Moreover, higher cyclic softening ratio by a factor of two was measured in the vertical samples when the strain amplitude was above 0.6%. No porosity defects were found in the material. Cracks were initiated from α lath due to cyclic slip localisation.Item Open Access Data: Fatigue crack growth behavior in an aluminum alloy Al–Mg–0.3Sc produced by wire based directed energy deposition process(Cranfield University, 2023-08-04 15:41) Ye, Jin; Khadar Syed, Abdul; Zhang, Xiang; Eimer, Eloise; Williams, StewartAdditive manufacturing (AM) of Al-Mg-Sc alloys has received considerable interest from the aerospace industry owing to their high specific strength and suitability for AM. Since damage tolerance is a mandatory requirement for safety critical aerospace structures, this study has investigated the fatigue crack growth behaviour in an Al-Mg-0.3Sc alloy made by the wire and arc additive manufacturing. Tests were conducted with two different crack orientations at load ratios 0.1 and 0.5. At the lower load ratio and lower stress intensity factor range (10 MPa m1/2, isotropic crack growth rate property was measured; grain size effect was overcome by the mechanical factor (the stress intensity factor). At the higher load ratio 0.5, both the threshold and the critical values of the stress intensity factor range were reduced. Finally, the modified Hartman-Schijve equation was successfully employed to represent the crack growth rates including the threshold and the fast crack growth regions.