  Digital image correlation (DIC) and crystal plasticity simulation were
utilised to study cold dwell behaviour in a coarse grain Ti-6Al alloy at 3
different temperatures up to 230 C. Strains extracted from large volume grains
were measured during creep by DIC and were used to calibrate the crystal
plasticity model. The values of critical resolved shear stresses (CRSS) of the
two main slip systems (basal and prismatic) were determined as a function of
temperature. Stress along paths across the boundaries of two grain pairs, (1) a
`rogue' grain pair and (2) a `non-rogue' grain pair, were determined at
different temperatures. Load shedding was observed in the `rogue' grain pair,
where a stress increment during the creep period was found in the `hard' grain.
At elevated temperatures, 120 C was found to be the worst-case scenario as the
stress difference at the grain boundaries of these two grain pairs were found
to be the largest among the three temperatures. This can be attributed to the
fact that the strain rate sensitivity of both prismatic and basal slip systems
is at its greatest in this worst-case scenario temperature.
