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Lecture

Visco-Plastic Self-Consistent Modelling to Determine Dominant Slip and Twinning Systems in Magnesium WE43 at High Strain Rate

Wednesday (08.11.2017)
12:20 - 12:40
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Magnesium WE43 (3.7-4.3% Y, 2.4-4.4% RE, 0.4% Zr) was initially developed for its creep resistance and thermal properties, but recent research interest has been in the field of dynamic deformation, to determine the suitability of wrought WE43 as a lightweight armour alloy.

This work aimed to determine the dominant slip and twinning systems during high strain rate compressive deformation and to compare this to quasi-static behaviour. Experimental testing at strain rates between 400-2300 s-1 in compression was undertaken on a Split Hopkinson Pressure Bar, to determine the stress-strain response of the material at high strain rates. These results were interpreted using a Visco-Plastic Self-Consistent (VPSC) crystal plasticity model.

The model simulates plastic deformation of an alloy based upon texture, crystal structure, and behaviour of individual deformation modes, including slip and twinning. The VPSC model used here was developed by Tomé and co-workers at Los Alamos National Laboratory, USA. It has been widely used to model deformation in magnesium. To produce accurate predictions, the critical resolved shear stresses for each deformation system are calibrated to the overall stress-strain response.

From the VPSC model, the dominant slip and twinning modes were determined. These predictions were compared with observations of post-test specimens made using optical and scanning electron microscopy, coupled with electron backscattered diffraction (EBSD).

The predictions show the expected behaviour with regard to deformation mode activity; for example compression along the rolling direction is predicted to lead to activation of twinning due to the crystallographic texture. The predictions show there is not a significant change in deformation mode activity at high strain rate studied compared with that under quasi-static conditions, consistent with the measured mechanical response. This suggests that for strain rates of up to 2300 s-1 there is no change in the fundamental deformation behaviour of WE43.

 

Speaker:
Andrew Platts
The University of Manchester
Additional Authors:
  • Prof. Joseph Robson
    University of Manchester
  • Dr. Matthew Lunt
    DSTL

Dateien

Category Short file description File description File Size
Short Paper First Submitted Version The first version of the Short Paper submitted for the LightMAT 2017 Conference in Bremen this November. 523 KB Download