Effect of high temperature multidirectional asynchronous rolling on microstructure and mechanical properties of LZ91 magnesium-lithium alloy

Dual-phase magnesium-lithium alloys sheets were rolled at four different rolling methods: asynchronous rolling, multi-directional asynchronous rolling, high temperature asynchronous rolling and high temperature multi-directional asynchronous rolling. The microstructure, mechanical properties and texture characteristics were comprehensively analyzed through optical microscope, MTS E43 universal testing machine and X-ray diffraction, respectively. The effects of temperature and rolling direction on microstructure and mechanical properties of magnesium-lithium alloy were discussed. The results show that alpha-Mg phase is largely elongated along the rolling direction and becomes thinner along the normal direction. The lowest thickness of the alpha-Mg phase is 2.6 mu m rolled by high temperature multi-directional asynchronous rolling. Multi-directional asynchronous rolling samples have the best mechanical properties as its yield strength, ultimate tensile strength, elongation are 149 MPa and 167 MPa, 14.5%, respectively.The double peaks texture is tilt along the normal direction with an angle of 45 degrees by multi-directional rolling, while the RD tilt angle of double peaks texture decreases due to the high temperature rolling. The intensity of R-cube texture is the strongest after rolling. beta-Li rolling texture is transformed into {001}100 texture by high temperature multi-directional asynchronous rolling, which is beneficial to the multi-slip of {011}1${\rm{\bar 1}}$1 slip system.