“…If fcc and bcc crystal plasticity continuum models have already been extensively studied (Cuitiño and Ortiz, 1993;Anand and Kothari, 1996;Anand, 2004;Houtte et al, 2006;Zhao et al, 2007;Kuchnicki et al, 2008;Jérusalem et al, 2008;Roters et al, 2010;Lee et al, 2010;Liu et al, 2011;Thamburaja, 2010;Rossiter et al, 2010;Zamiri and Pourboghrat, 2010;Watanabe et al, 2010;Sung et al, 2010), similar efforts have been much scarcer for HCP metals (Staroselsky, 1998;Staroselsky and Anand, 2003;Graff et al, 2007;Mayeur and McDowell, 2007;Tang et al, 2009;Mayama et al, 2009;Prakash et al, 2009;Choi et al, 2010b;Choi et al, 2010a;Lévesque et al, 2010). Despite the relatively ancient interests in HCP metals, the intrinsic mechanisms of HCP crystalline deformation, such as twinning (generally more present than in fcc and bcc metals), twin-slip interaction, or twin polarization among others, are still, as of now, not fully understood (Jérusalem et al, 2008;Wang et al, 2009a;Yue et al, 2010;Shen et al, 2010).…”