Asymmetric Rolling of TZ73 Magnesium Alloy to Improve Its Ductility

Asymmetric rolling, i.e., upper and lower rolls having different circumferential speeds, is a novel technique to improve the ductility of Mg alloys. A newly developed TZ73 Mg alloy was squeeze cast, homogenized at 300 °C for 24 h, rolled at 350 °C by symmetric and asymmetric rolling, and annealed at 215 °C for 30 min. The microstructure was characterized by X-ray diffraction, scanning electron microscope equipped with energy-dispersive X-ray spectroscopy and electron backscattered diffraction. A weakening of basal texture with a concomitant increase in ductility was observed for asymmetrically rolled sheet while retaining the same strength as in symmetrically rolled sheet. Thus, tensile properties of 0.2% PS = 290 MPa, UTS = 332 MPa and El = 13% in hot rolled, and 0.2% PS = 182 MPa, UTS = 282 MPa and El = 21% in annealed condition were obtained for asymmetrically rolled sheet, which are extremely good for a rolled Mg alloy sheet.