高温多向异步轧制对LZ91镁锂合金组织和力学性能的影响EI北大核心CSCD

采用异步轧制、多向异步轧制、高温异步轧制、高温多向异步轧制四种不同的方式轧制双相镁锂合金板材。通过光学显微镜、MTS E43拉伸试验机和X射线衍射仪观察不同工艺轧制后合金的显微组织、力学性能以及织构特征,综合分析温度和轧制方向条件耦合对镁锂合金组织和力学性能的影响。结果表明:四种轧制工艺可以使α-Mg相沿轧制方向伸长,同时沿着轧制方向法向细化。高温多向异步轧制后α相厚度最低为2.6μm。多向异步轧制后材料的屈服强度、抗拉强度、伸长率分别为149,167 MPa,14.5%,其综合力学性能最优。多向轧制使双峰织构沿ND方向45°偏转,高温轧制使双峰织构由基极向RD方向偏转的角度降低。轧制后样品R-cube织构组分最强,高温多向异步轧制使β-Li相轧制织构转变成为{001}〈100〉织构,有利于{011}〈111〉滑移系发生多滑移。

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 α-Mg phase is largely elongated along the rolling direction and becomes thinner along the normal direction. The lowest thickness of the α-Mg phase is 2.6 μm 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° 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. β-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.