In this paper, the rolling textures of six magnesium alloys containing different levels of zinc and rare earth (e.g., mischmetal or Y) additions are examined. The overall texture strength and the basal pole intensity aligned with the sheet normal direction is lower for rare earth containing alloys than for conventional alloys. The distinct textures generated in this study allow investigation of the influence of texture on the mechanical response. The anisotropy of the yield and flow strengths is reversed and the planar anisotropy is reduced (r ~ 1) in comparison to conventional alloys. Both aspects of the anisotropy are related to the fact that the dominant texture components in the Mg-Zn-RE alloys place more grains in favourable orientations for basal slip and tensile twinning, particularly during transverse direction tension. Mg sheets with lower r-value promise to have improved forming behaviour, at least under straining conditions which call for thinning of the sheet.

Magnesium Research SummaryThe sheet formability of current magnesium alloys at ambient temperatures is poor; however, the formability at moderately elevated temperatures can be excellent. Cylindrical cup drawing tests are used to compare the warm forming characteristics of conventional alloy AZ31B with alloys containing lithium or yttrium solid solutions. While both types of experimental alloy can have better room-temperature ductility (ε f~2 5-30%) than AZ31B, only the lithium alloy has comparable or better deep-drawing capacity. The results are discussed in terms of the sheet anisotropy. Particular attention is drawn to the fact that magnesium alloys exhibit poor bending ductility due to their anisotropy and mechanical twinning-induced tension-compression strength asymmetry. Figure 11. The pole fi gure data collected from the inner and outer surface of the cup wall, which represent the outer and inner surface respectively during the bend and unbend, show evidence of mechanical twinning (e.g., note the strong basal intensity along the Z or drawing direction).