Cold Dwell Behaviour of Ti6Al Alloy: Understanding Load Shedding Using Digital Image Correlation and Crystal Plasticity Simulations

29 Pages Posted: 7 Jun 2021

See all articles by Yi Xiong

Yi Xiong

University of Oxford - Department of Materials

Nicolò Grilli

University of Oxford - Department of Materials

Phani S. Karamched

University of Oxford - Department of Materials

B-S. Li

University of Oxford - Department of Materials

Edmund Tarleton

University of Oxford - Department of Materials

Angus J. Wilkinson

University of Oxford - Department of Materials

Abstract

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.

Keywords: Cold dwell fatigue, Digital image correlation, Crystal plasticity, Load shedding, Titanium alloy

Suggested Citation

Xiong, Yi and Grilli, Nicolò and Karamched, Phani S. and Li, B-S. and Tarleton, Edmund and Wilkinson, Angus J., Cold Dwell Behaviour of Ti6Al Alloy: Understanding Load Shedding Using Digital Image Correlation and Crystal Plasticity Simulations. Available at SSRN: https://ssrn.com/abstract=3862135 or http://dx.doi.org/10.2139/ssrn.3862135

Yi Xiong (Contact Author)

University of Oxford - Department of Materials ( email )

Parks Road
Oxford, OX1 3PH
United Kingdom

Nicolò Grilli

University of Oxford - Department of Materials ( email )

Mansfield Road
Oxford, OX1 4AU
United Kingdom

Phani S. Karamched

University of Oxford - Department of Materials ( email )

B-S. Li

University of Oxford - Department of Materials ( email )

Parks Road
Oxford, OX1 3PH
United Kingdom

Edmund Tarleton

University of Oxford - Department of Materials

Parks Road
Oxford, OX1 3PH
United Kingdom

Angus J. Wilkinson

University of Oxford - Department of Materials

Parks Road
Oxford, OX1 3PH
United Kingdom

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