Plasticity in High Strength Beta Titanium Alloys

Plasticity of high strength titanium alloys is influenced by the scale and distribution of intragranular. We aim to develop a relationship. between microstructural length scales, microtexture and the mean free path for slip. We also aim to develop a predictive model for yield strength in these materials using crystal plasticity techniques. We have quantitatively determined structural parameters associated with a phase distribution and morphology as a function of heat treatment in the high strength, metastable beta alloy Ti 5553. Compression tests had been carried out at room temperature to show the variation of yield strength and work hardening as a function of these structural parameters. Surface slips offsets had been analysed in relation to the scale of the alpha microstructure and it has been shown that slip initiates in the b phase on the {112} and lt;111 and gt; system in the form of heterogenous slip bands. Slip lengths are restricted by the interaction of the slip bands with a variants, and therefore depends on the a variant distribution statistics. Yield strength has been shown to scale with slip length and alpha interparticle spacing. Strain partitioning has been examined by both DIC and qualitative EBSD techniques. These experimental results are complemented by crystal plasticity simulations of single beta grains containing alpha variant distributions.