Modeling Texture, Twinning and Hardening Evolution during Deformation of Hexagonal Materials

Abstract:

Hexagonal materials deform plastically by activating diverse slip and twinning modes. The activation of such modes depends on their relative critical stresses, function of temperature and strain rate, and the orientation of the crystals with respect to the loading direction. For a constitutive description of these materials to be reliable, it has to account for texture evolution associated with twin reorientation, and for the effect of the twin barriers on dislocation propagation and on the stress-strain response. In this work we introduce a model for twinning which accounts explicitly for the composite character of the grain, formed by a matrix with embedded twin lamellae which evolve with deformation. Texture evolution takes place through reorientation due to slip and twinning. The role of the twins as barriers to dislocations is explicitly incorporated into the hardening description via a directional Hall-Petch mechanism. We apply this model to the interpretation of compression experiments both, monotonic and changing the loading direction, done in rolled Zr at 76K.

• Periodical: Materials Science Forum (Volumes 495-497)
• Pages: 1001-1006
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.495-497.1001
• Online since: September 2005
• Authors: Carlos Tomé, George C. Kaschner
• Keywords: Twinning, Hardening, Hexagonal Materials, Polycrystal Model

References

[1] P. Van Houtte, Acta Metall. Vol 26 (1978) p.591.

[2] C.N. Tomé, R.A. Lebensohn and U.F. Kocks, Acta metall. Mater. Vol 39 (1991) p.2667.

[3] R.A. Lebensohn and C.N. Tomé, Acta metall. mater. Vol 41 (1993) p.2611.

[4] C.N. Tomé, P.J. Maudlin, R.A. Lebensohn and G.C. Kaschner, Acta Mater. Vol 49 (2001) p.3085.

[5] D.W. Brown, S.P. Abeln, W.R. Blumenthal, M.A.M. Bourke, R.D. Field and C.N. Tomé Metall. and Materials Transactions A (in press).

[6] S.R. Agnew, M.H. Yoo and C.N. Tomé, Acta Mater. Vol 49 (2001) p.4277.

[7] A.A. Salem, S.R. Kalidindi and R.L. Semiatin, Acta Mater. (in press).

[8] L. Remy, Metall. Trans. Vol 12A (1981) p.387.

[9] J.D. Livingston and B. Chalmers, Acta metall. Vol 5 (1957) p.322.

[10] Z. Shen, R.H. Wagoner and W.A.T. Clark, Scripta metall. Vol 20 (1986) p.921.

[11] M.H. Yoo, Trans. Metall. Soc. of AIME Vol 245 (1969) p. (2051).

[12] R.A. Lebensohn, Modeling Sim. Mats. Sc. Eng. Vol 7 (1999) pp.739-30% IPC predicted.

7.

[1] 0.

[1] 4.

[2] 0.

[2] 8.

[4] 0.

[5] 6.

0 0. 1 0. 2 0. 3 0 200 400 600 800 1000 STRESS [MPa] IPC 27% IPC measured.

7.

[1] 0.

[1] 4.

[2] 0.

[2] 8.

0 0. 1 0. 2 0. 3 0 200 400 600 800 1000 STRESS [MPa] TTC 30% TTC predicted.

7.

[1] 0.

[1] 4.

[2] 0.

[2] 8 24% TTC measured.

7.

[1] 0.

[1] 4.

[2] 0.

[2] 8 TTC -> IPC predicted.

7.

[1] 0.

[1] 4.

[2] 0.

[2] 8.

[4] 0.

[5] 6 TTC -> IPC measured.

7.

[1] 0.

[1] 4.

[2] 0.

[2] 8.

0 0. 1 0. 2 0. 3 0 200 400 600 800 1000 IPC TTC STRESS [MPa] IPC -> TTC predicted.

7.

[1] 0.

[1] 4.

[2] 0.

[2] 8.

[4] 0.

0 0. 1 0. 2 0. 3 0 200 400 600 800 1000 TTC IPC STRESS [MPa] IPC -> TTC measured.

7.

[1] 0.

[1] 4.

[2] 0.

[2] 8 Figure 3: Predicted and experimental stress-strain response for high-purity rolled Zr tested in compression at 76K and 10 -3s-1 rate. a) monotonic In-Plane Compression (IPC); b) monotonic Through-Thickness Compression (TTC); c) pre-load in TTC and reload in IPC; d) pre-load in IPC and reload in TTC. Also shown are the final (0002) pole figures predicted with the Composite Grain model and measured by neutron diffraction at LANSCE-LANL.