高频低幅循环扭转下镁合金强韧化效应与微结构演化  

Strong toughening effect and microstructural evolution of magnesium alloys under high-frequency and low-amplitude cycling torsion

作　　者：蓝永庭[1] 杨帅涛 魏中顺 LAN Yongting;YANG Shuaitao;WEI Zhongshun(School of Mechanical and Automotive Engineering,Guangxi University of Science and Technology,Liuzhou 545616,China)

机构地区：[1]广西科技大学机械与汽车工程学院,广西柳州545616

出　　处：《广西科技大学学报》2025年第2期33-41,共9页Journal of Guangxi University of Science and Technology

基　　金：国家自然科学基金项目(12262003);广西自然科学基金项目(2022GXNSFAA035537);广西科技大学博士基金项目(校科博21Z13)资助。

摘　　要：商用镁合金的强度和塑性相对较低,且难以同时提高。扭转变形可使材料内部位错等微结构呈梯度变化,各梯度层之间相互协调能够改善镁合金材料的强度和塑性。为了探究循环扭转周期对镁合金材料强度和塑性的影响机制,本文对经高频低幅循环扭转变形处理后的AZ31镁合金棒材开展单轴加载试验和微结构分析。结果表明:随着循环周期的增加,镁合金的屈服强度提升,抗压强度先提升后降低,拉伸与压缩屈服强度的不对称性降低,拉伸伸长率降低,而压缩伸长率未明显变化;晶粒尺寸变化较小,孪晶数量增加,且沿径向呈梯度分布;循环扭转过程中以柱面滑移为主,位错密度增加,且沿半径方向呈逐渐增加的梯度结构;柱面(110)β的位错密度与伸长率的变化呈相反关系。本研究可为扭转变形技术改善AZ31的综合力学性能提供重要的试验数据,有助于进一步优化镁合金的加工工艺。The strength and plasticity of commercial magnesium alloys are still relatively low,and it is difficult to improve them at the same time.Torsion deformation can cause gradient changes in the microstructure of materials,such as dislocations.The coordination between gradient layers can improve the strength and plasticity of magnesium alloy material.In order to investigate the mechanism of the influence of cyclic torsion on the strength and plasticity of magnesium alloy materials,uniaxial loading tests and the microstructure analysis were conducted on AZ31 magnesium alloy bars after high frequency and low amplitude cyclic torsion deformation treatment.The experimental results show that with the increase in the cycle period,the yield strength of magnesium alloy increases,the compressive strength first increases and then decreases,the asymmetry between tensile and compressive yield strength decreases,and the tensile elongation decreases,while the compressive elongation remains unchanged.The variation in grain size is relatively small.The number of twins increases and is distributed along a radial gradient.Cylindrical slip is dominant in the cyclic torsion process.The dislocation density increases and shows a gradually increasing gradient structure along the radius direction.The dislocation density and elongation of cylindrical(100)βexhibit an inverse relationship.This article can provide important experimental data for improving the comprehensive mechanical property of AZ31 using torsional deformation technology.

关 键 词：AZ31镁合金 高频率低幅值 强度 塑性 位错密度 

分 类 号：TG146.22[一般工业技术—材料科学与工程]