Identifying the most damaging conditions for cold dwell fatigue in Ti-alloys
|Starts:||13:00 5 Sep 2018|
|Ends:||14:00 5 Sep 2018|
|What is it:||Seminar|
|Organiser:||Department of Materials|
The room temperature fatigue life, termed cold dwell fatigue, of many titanium alloys including Ti-6Al-4V, is drastically reduced when subjected to a hold period at the peak stress.
During a dwell period, modelling simulations hypothesise that localised time dependent plasticity in soft grains leads to load shedding and an increase in stress within the neighbouring
hard grain. If this grain reaches a critical stress, it fractures. Limited experimental evidence exists that corroborate these findings; this work seeks to explore the load-hold conditions
that are most damaging. Simple load-hold compression tests are performed that investigate the effect of holding stress, time held at load and initial loading rate. Both the macroscopic
response and post-mortem microscopic states are characterised with high-resolution electron backscatter diffraction measurements of residual intragranular stresses and geometrically
necessary dislocations densities. The findings will be compared to crystal plasticity finite element results that have explored these experimental variables.
Organisation: University of Birmingham
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