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Low cycle fatigue behavior of the extruded AZ80 magnesium alloy under different strain amplitudes and strain rates

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Journal of Magnesium and Alloys 2016年第3期4卷 181-187页

作者： Cong Wang tianjiao luo Yuansheng Yang Institute of Metal Research Chinese Academy of SciencesShenyang 110016China

Low cycle fatigue behavior of extruded AZ80 magnesium alloy was investigated under uniaxial tension-compression at different strain amplitudes and strain rates.The results show that the extruded AZ80 magnesium alloy exhibits cyclic hardening at strain amplitudes ranging from 0.4%to 1.0%,the asymmetry of hysteresis loops becomes increasingly obvious when the strain amplitude increases.Higher strain rates correspond to higher stress amplitudes,high mean stresses and short fatigue life.{10–12}extension twins play a role in the cyclic deformation under higher strain amplitudes(0.8%,1.0%).The relationship between total strain energy density and fatigue life can be described by the modified Morrow model.The effect of strain rate on the fatigue life can also be predicted by the model.

关键词： Low cycle fatigue Magnesium alloy Extruded AZ80 Strain amplitude Strain rate

Residual stress and precipitation of Mg-5Zn-3.5Sn-1Mn-0.5Ca-0.5Cu alloy with different quenching rates

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Journal of Magnesium and Alloys 2021年第2期9卷 604-612页

作者： Cong Wang tianjiao luo Yunteng Liu Qiuyan Huang Yuansheng Yang Institute of Metal Research Chinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering Northeastern UniversityShenyang 110819China Shandong Key Laboratory for High Strength Lightweight Metallic Materials Advanced Materials InstituteShandong Academy of SciencesShandong 250014China

The effect of the quenching rate after solution treatment on the residual stress and precipitation behavior of a high strength Mg-5 Zn-3.5 Sn-1 Mn-0.5 Ca-0.5 Cu plate is studied.The simulation results show decreasing temperature gradient in the plate with decreasing quenching rate,which leads to weakened inhomogeneous plastic deformation and decreased residual stress.No dynamic precipitation on the grain boundary happens after either cold water cooling or air cooling,however,air cooling leads to dynamic precipitation of Mg-Zn phase on Mn particles around which a low-density precipitate zone develops after aging treatment.Moreover,the fine and densely distributed Mg-Zn precipitates observed after aging treatment of the cold water cooled alloy are replaced by coarse precipitates with low density for the air cooled alloy.Both the low-density precipitate zone near Mn particles and the coarsening of precipitates are the source of the decrease in hardness and tensile properties of the air cooled alloy.The residual stress drops faster than the hardness with decreasing quenching rate,which makes it possible to lower the residual stress without sacrificing too much age-hardening ability of the alloy.

关键词： Mg-5Zn-3.5Sn-1Mn-0.5Ca-0.5Cu alloy Solution treatment Quenching rate Residual stress Precipitation Age-hardening

Fluidity, Microstructure, and Tensile Properties of Sub-rapidly Solidified Mg-6Al-4Zn-xSn(x=0,0.6,1.2,1.8) Alloy

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Acta Metallurgica Sinica(English Letters) 2021年第9期34卷 1265-1276页

作者： Jie Cui tianjiao luo Yingju Li Xiaohui Feng Qiuyan Huang Yuansheng Yang School of Materials Science and Engineering Northeastern UniversityShenyang 110819China Institute of Metal Research Chinese Academy of ScienceShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China

In this paper, the infl uence of the Sn element on the melt viscosity, grain size, shrinkage, and tensile properties of the subrapidly solidified Mg-6Al-4Zn alloy was studied. The results showed that the melt viscosity of the Mg-6Al-4Zn alloy was greatly decreased because of the addition of Sn. As the content of Sn increased from 0 to 1.8 wt.%, the grain size of the alloy was refined, and the dendrite microstructure was changed to rose-shaped ones simultaneously. The decreased melt viscosity and refined microstructure were conductive to the feeding of melt, which contributed to the reduction in volume fraction of shrinkage. The volume fraction of shrinkage of the Mg-6Al-4Zn-1.2 Sn alloy was reduced by 30.8%, compared with that of the alloy without Sn addition. Tensile properties of the Mg-6Al-4Zn-x Sn alloys were increased firstly and then decreased with the augmented Sn content. The yield strength, ultimate tensile strength, and elongation of the alloy containing 1.2 wt.% Sn were 21.4%, 39.5%, and 259.0% higher than those of the alloy without Sn addition, respectively. The addition of Sn was considered to reduce the shrinkage of the sub-rapidly solidified Mg-6Al-4Zn magnesium alloy and thus improved its tensile properties. To identify the mechanism, the effect of Sn on the volume fraction of shrinkage was discussed from three aspects of melt viscosity, grain refinement, and volume fraction of eutectic phases.

关键词： Magnesium alloy Melt viscosity Grain size Shrinkage Tensile properties

Effect of Pulsed Magnetic Field on the Residual Stress of Rolled Magnium Alloy AZ31 Sheet

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Acta Metallurgica Sinica(English Letters) 2021年第1期34卷 45-53页

作者： Meng Yan Cong Wang tianjiao luo Yingju Li Xiaohui Feng Qiuyan Huang Yuansheng Yang Institute of Metal Research Chinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China

A novel method of pulsed magnetic field(PMF)treatment was developed to eliminate the residual stress of rolled magnesium alloy AZ31 sheet in this study.The eff ect of PMF on residual stress of rolled AZ31 sheet was investigated and its mechanism was analyzed.The experimental results revealed that the pulse frequency had a significant impact on residual stress.After 10.0 Hz PMF treatment,the average and maximum reduction rates of residual stress along the rolled direction were 26.6%and 30.3%,respectively.It was found that the dislocation density and parallel dislocation in grains of the rolled sheet increased after it was treated by the pulsed magnetic field.The simulation results showed that the Lorentz force generated by the pulsed magnetic field can lead to basal slip,thereby resulting in local plastic deformation.Besides,the Joule heat produced during the PMF treatment was conducive to the elimination of residual stress.

关键词： Wrought magnesium alloy Residual stress Pulsed magnetic field Rolled AZ31 sheet

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数字赋能乡村全过程人民民主的实践路径探析

智慧农业导刊 2024年第15期4卷 31-34页

作者：罗天骄广西师范大学政治与公共管理学院广西桂林541006

全过程人民民主是中国特色社会主义发展的有力举措,也是人民当家作主的必然追求,数字时代下数字赋能使得乡村全过程人民民主发展呈现新的秩序与活力。该文立足于数字赋能中全过程人民民主治理的多主体参与基层管理积极化、新技术提升事... 详细信息

全过程人民民主是中国特色社会主义发展的有力举措,也是人民当家作主的必然追求,数字时代下数字赋能使得乡村全过程人民民主发展呈现新的秩序与活力。该文立足于数字赋能中全过程人民民主治理的多主体参与基层管理积极化、新技术提升事务办理公平化和新思想引领下的办事效率化的现状,针对在当前发展中乡村全过程人民民主治理产生数字办事流程下主体力不从心、数字技术融入乡村领域水土不服、工具理性与情感交融内在冲突等问题,需要构建新时代乡村全过程人民民主治理主体,发展有生产力的数字全过程人民民主治理流程,促进数字工具与主体情感的交融化发展,为乡村全过程人民民主注入新的活力。

关键词：数字技术数字赋能乡村治理全过程人民民主乡村发展

Age hardening responses of as-extruded Mg-2.5Sn-1.5Ca alloys with a wide range of Al concentration

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Journal of Materials Science & Technology 2020年第3期38卷 39-46页

作者： Qiuyan Huang Yang Liu Aiyue Zhang Haoxin Jiang Hucheng Pan Xiaohui Feng Changlin Yang tianjiao luo Yingju Li Yuansheng Yang Institute of Metal Research Chinese Academy of SciencesShenyang110016China Key Laboratory for Anisotropy and Texture of Materials(MOE) School of Materials Science and EngineeringNortheastern UniversityShenyang110819China Research Center for Metallic Wires Northeastern UniversityShenyang110819China State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an710072China

This article aims to explore the age hardening responses of both as-extruded and as-aged Mg-2.5 Sn-1.5 Ca-x Al alloys(x=2.0,4.0 and 9.0 wt%,termed TXA322,TXA324 and TXA329,respectively)through microstructural and mechanical characterization.Results indicate that grain size of as-extruded TXA322,TXA324 and TXA329 alloys were^16μm,~10μm and^12μm,respectively.A number ofanddislocations were observed in all the as-extruded samples.Guinier–Preston(GP)zones were evidently identified in TXA322 alloy,while only a small number of Mg17 Al12 phases existed in both TXA324 and TXA329 alloys.An aging treatment facilitated the precipitation of a high number density of GP zones within the matrix of TXA322 alloy.In contrast,no obvious nano-precipitates were in as-aged TXA324 alloy.Numerous nano-Mg17 Al12 phases were formed through a following aging treatment in TXA329 alloy.In terms of mechanical properties,it is apparent that an increment in ultimate tensile strength of^46 MPa and^40 MPa was yielded in peak-aged TXA322 and TXA329 alloys,while no obvious variations in UTS were present in peak-aged TXA324 alloy,in comparison with the as-extruded counterparts.

关键词： Magnesium alloys Age hardening Precipitations Dislocations Mechanical properties

Mg-8Zn-4Al-0.5Cu-0.5Mn-xLi高模量铸造镁合金的组织和性能

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材料研究学报 2024年第3期38卷 187-196页

作者：刘晨野罗天骄李应举冯小辉黄秋燕郑策朱成杨院生中国科学院金属研究所沈阳110016 中国科学技术大学材料科学与工程学院沈阳110016

设计和制备Mg-8Zn-4Al-0.5Cu-0.5Mn-x Li(x=0,3,5,7)(%,质量分数)系列高比模量的镁合金,研究了它的组织和性能。Li含量为3.14%和5.37%的两种镁合金,其基体为单相α-Mg,在晶界析出骨骼状Mg_(32)(Al,Zn)49相,在晶粒内有颗粒状Mg_(5)Al_(2)Zn_(2)相和Al_(2)Mn相;Li含量为7.57%的合金,其基体主要为双相组织α-Mg+β-Li。添加Li元素后在晶界附近生成的共晶组织由α-Mg相和层片状AlLi相组成,并随着Li含量的提高层片状AlLi相的含量随之提高。随着Li含量的提高,合金的屈服强度呈逐渐提高的趋势,而抗拉强度基本上不变,合金的弹性模量呈现先提高后降低的趋势。铸态合金ZA84-5Li的弹性模量可达51.89 GPa,比纯Mg的弹性模量高7 GPa,但是其力学性能基本不变,屈服强度为141 MPa,抗拉强度为189 MPa,密度为1.71 g/cm^(3)。

关键词：金属材料镁合金第二相强化显微组织弹性模量

基于不同优化策略的国六汽车起重机排放特性研究

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南方农机 2024年第2期55卷 154-158页

作者：高洁贾佳奇杨锦天董庆奇董浩王浩伟罗天娇中机科(北京)车辆检测工程研究院有限公司北京102100 国家工程机械质量检验检测中心北京102100 中机寰宇(山东)车辆认证检测有限公司山东德州253000

为了有效控制重型柴油车排放水平,改善大气质量。选取一辆N3类国六重型汽车起重机,采集PEMS路谱,按照PEMS工况曲线在底盘测功机上开展不同优化策略下的排放测试。结果表明:国六重型汽车起重机现有的后处理技术路线可以有效控制NOx、CO、... 详细信息

为了有效控制重型柴油车排放水平,改善大气质量。选取一辆N3类国六重型汽车起重机,采集PEMS路谱,按照PEMS工况曲线在底盘测功机上开展不同优化策略下的排放测试。结果表明:国六重型汽车起重机现有的后处理技术路线可以有效控制NOx、CO、CO_(2)和PN排放,但相对于正常状态下的车辆,采用不同的优化策略使得排放有所上升,尤其是NOx和PN,上升效果更为明显,平均提高了60%~90%。NOx比排放随速度的增加而降低,具体表现为市区>市郊>高速,比排放最高的区域出现在市区工况。车辆经过累碳(4 h和8 h)后的碳载量对NOx排放并无明显影响。此外,NOx瞬时排放和排气流量、行驶速度呈现正相关。优化扭矩响应和尿素喷射策略导致CO排放量急剧增加,排气温度和排气流量也会对DOC装置氧化CO产生不良影响。虽然高速工况下发动机负荷增加、缸内缺氧使得燃烧不充分,CO瞬时排放增加,但是此时发动机功率较高,导致CO比排放处于较低水平。CO_(2)比排放总体较为稳定,个体间差异不大。PN排放与车辆行驶速度、发动机负荷存在很大关系。优化喷嘴喷射和尿素喷射策略导致PN排放成倍增加。从整体来看,汽车起重机污染物排放结果均远低于国六排放标准限值,表明下阶段排放标准污染物排放限值仍有较大下降空间。

关键词：汽车起重机 PEMS工况优化策略排放特性

Microstructures and mechanical properties of Mg-8Al-1Nd-0.5Zn-xSr alloys

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Microstructures and mechanical properties of Mg-8Al-1Nd-0.5Z...