Texture and Mechanical Properties of AZ31 Magnesium Alloy Sheets Processed by Symmetric/Asymmetric Combination Hot-Rolling

Conventional symmetric rolling enhances yield strength by forming basal texture, while asymmetric rolling can improve formability by inclining the c-axis of hcp crystal. In this study, the combination rolling consisting of symmetric and asymmetric hot rolling has been performed to simultaneously improve formability and maintain high strength of AZ31 magnesium alloy sheet. The symmetrically/asymmetrically combination hot-rolled and annealed sheet exhibits a broadened texture having double peaks with tilt angles of 0 degrees and 40 degrees from ND toward RD with respect to the c-axis. Correspondingly, this sheet shows relatively high yield strength of 123 MPa and large elongation of 24.7%. As for cup drawing test, the conventional warm-rolled sheet is barely formed at 175 degrees C, but the symmetrically/asymmetrically combination rolled sheet can be formed at temperature as low as 75 degrees C. These results indicate that the symmetric/asymmetric combination hot-rolling leads to a unique texture with good balance of formability and strength.