Determination of Ti-6242 α and β slip properties using micro-pillar test and computational crystal plasticity

The properties and behaviour of an  colony Ti-6242 alloy have been investigated at 20C utilising coupled micro-pillar stress relaxation tests and computational crystal plasticity. The -phase slip strength and intrinsic slip system strain rate sensitivity have been determined, and the -phase shown to have stronger rate sensitivity than that for the  phase. Close agreement of experimental observations and crystal plasticity predictions of micro-pillar elastic-plastic response, stress relaxation, slip activation in both  and -phases, and strain localisation within the  pillars with differing test strain rate, β morphology, and crystal orientations is achieved, supporting the validity of the properties extracted. The -lath thickness is found to affect slip transfer across the  colony, but not to significantly change the nature of the slip localisation when compared to pure -phase pillars with the same crystallographic orientation. These results are considered in relation to rate-dependent deformation, such as dwell fatigue, in complex multiphase titanium alloys.