Elasto-viscoplastic tensile behavior of as-forged Ti-1023 alloy: Experiments and micromechanical modeling

This works focused on the mechanical behavior of an 'as-forged' Ti-1023 alloy used in airframe forging applications. Its microstructure, characterized by SEM and EBSD, was composed by 15% of primary ap nodules (2-5 mu m in size) embedded in millimeter long beta grains partially fragmented into equiaxed beta subgrains of 5-10 mu m. Further neutron diffraction analysis indicated an almost random beta texture. Tensile tests at different strain rates were performed. A very low strain rate sensitivity was observed. The contribution of each phase to the overall mechanical behavior was numerically investigated by a two-phase elasto-viscoplastic self-consistent (EVPSC) model with affine-type linearization. Internal stresses arising from elastic and plastic strain incompatibilities were analyzed. Throughout the mechanical loading, {100} beta oriented grains were more deformed than {111} beta-grains and all the a nodules. The onset of plasticity occurred sequentially in the beta phase, initially in {110} beta grains followed by {111} beta and then {100} beta ones. The effect of the crystallographic texture on slip activity was also studied through simulations made with a synthetic rotated cube beta texture, typical of beta-working, while considering a textures in Burgers Orientation Relationship (BOR) with the beta phase or being random.