Effects of Cross-rolling on the Microstructure and Mechanical Properties of AZ31B Magnesium Alloy

In this study, AZ31B Mg alloy samples were rolled in two different routes. One sample was normally rolled by maintaining the rolling direction (RD) and the other one was cross rolled by rotating the RD once by 90 degrees around the normal direction (ND). Deformed bands, similar to shear, were observed in response to increasing deformation in the sheets. The texture was split by approximately 10-15 degrees from the ND toward the RD in both sheets. The degree of the split texture rotation depended on the direction of the deformed bands. The grains in the deformed bands had a weak texture owing to the rotated c-axis of the hexagonal close-packed (hcp) structure. The texture affected the mechanical properties because of the easy basal < a > slip for the observed split basal texture. Cross rolling definitely lowered the total elongation which was attributed to the frequent development of deformation bands in the cross rolled sample. It turned out that occurrence of a large number of compression twins in the cross rolled sample accelerated hardening of the AZ31B Mg alloy during the tensile deformation. The r-value of the cross-rolled sample was higher than that of the normal-rolled sample.