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Predicting the effect of cooling rates and initial hydrogen concentrations on porosity formation in Al-Si castings

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Materials Genome Engineering Advances 2024年第3期2卷 117-129页

作者： Qinghuai Hou Junsheng Wang Yisheng Miao Xingxing Li xuelong wu Zhongyao Li Guangyuan Tian Decai Kong Xiaoying Ma Haibo Qiao Wenbo Wang Yuling Lang School of Materials Science and Engineering Beijing Institute of TechnologyBeijingChina Advanced Research Institute of Multidisciplinary Science Beijing Institute of TechnologyBeijingChina School of Mechanical Engineering Beijing Institute of TechnologyBeijingChina CITIC Dicastal Co. Ltd.QinhuangdaoHebei ProvinceChina

Al-Si alloys are widely used in automotive casting components while microporosity has always been a detrimental defect that leads to property *** this study,a coupled three-dimensional cellular automata(CA)model has been used to predict the hydrogen porosity as functions of cooling rate and initial hydrogen *** quantifying the pore characteristics,it has been found that the average equivalent pore diameter decreases from 40.43 to 23.98μm and the pore number density increases from 10.3 to 26.6 mm^(−3)as the cooling rate changes from 2.6 to 19.4℃/s at the initial hydrogen concentration of 0.25 mL/100 *** is also notable that the pore size increases as the initial hydrogen concentration changes from 0.15 to 0.25 mL/100 g while the pore number remains *** addition,the linear regression between secondary dendrite arm spacing and the equivalent pore diameter has been studied for the first time,matching well with *** work exhibits the application of CA model in future process optimization and robust condition design for advanced automotive parts made of Al-Si alloys.

关键词： Al-Si alloy cellular automata cooling rate microporosity secondary dendrite arm spacing solidification

基于因子分析法的昆明市西山森林公园游客满意度影响评价

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西部林业科学 2024年第1期53卷 172-177,187页

作者：柳娥伍学龙崔厅陈建成云南省社会科学院经济研究所云南昆明650034 云南农业职业技术学院云南昆明650031 西南林业大学经济管理学院云南昆明650224 北京林业大学经济管理学院北京100083

构建生态文明是中华民族实现长治久安的重要战略举措,森林公园是践行“两山理论”的重要载体,对社会经济发展影响重大。以昆明市西山森林公园为研究对象,采用问卷调查法和参与观察法对西山森林公园游憩及游客满意度开展研究,构建出森林... 详细信息

构建生态文明是中华民族实现长治久安的重要战略举措,森林公园是践行“两山理论”的重要载体,对社会经济发展影响重大。以昆明市西山森林公园为研究对象,采用问卷调查法和参与观察法对西山森林公园游憩及游客满意度开展研究,构建出森林旅游形象、感知质量、感知价值、游客满意度共4个逻辑变量对西山森林公园游客满意度进行测评。结果显示:游客的满意度和森林公园的旅游形象之间存在着明显的正向联系;森林公园的环境和设施会直接影响游客的体验和满足感;森林公园的游客满意度越高,它的感知价值就越高。在此基础上,提出根据景区实际发展及发展前景制定发展策略、强化基础设施建设等建议来提升森林公园游客满意度。

关键词：绿色发展因子分析西山森林公园昆明市

不同养护温度下早龄期混凝土导热系数试验研究

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混凝土 2024年第3期 53-56页

作者：韩卓伟王起才代金鹏武学龙楚昊兰州交通大学甘肃省道路桥梁与地下工程重点实验室甘肃兰州730070 兰州交通大学道桥工程灾害防治技术国家地方联合工程实验室甘肃兰州730070 酒钢(宏达)建材有限责任公司甘肃嘉峪关735199

为了研究低温环境下的混凝土早龄期的导热系数,采用热流计法导热仪对混凝土试件进行了导热系数测试,考察了-5℃、5℃和20℃养护环境下的早龄期混凝土导热系数,同时测定了各龄期混凝土的抗压强度。采用低场核磁共振技术,研究了不同养护... 详细信息

为了研究低温环境下的混凝土早龄期的导热系数,采用热流计法导热仪对混凝土试件进行了导热系数测试,考察了-5℃、5℃和20℃养护环境下的早龄期混凝土导热系数,同时测定了各龄期混凝土的抗压强度。采用低场核磁共振技术,研究了不同养护温度下混凝土各龄期的含水率与孔隙率。结果表明:混凝土的含水率与孔隙率随龄期增大逐渐减小,抗压强度随龄期增大逐渐增大,导热系数与龄期和养护温度呈现负相关。

关键词：早龄期导热系数抗压强度低场核磁共振

Seeing through Materials:X-Ray Imaging Using Computed Tomography

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Journal of Beijing Institute of Technology 2023年第4期32卷 494-516页

作者： Yisheng Miao Chengpeng Xue xuelong wu Zhongyao Li Junsheng Wang School of Materials Science and Engineering Beijing Institute of TechnologyBeijing 100081China Advanced Research Institute of Multidisciplinary Science Beijing Institute of TechnologyBeijing 100081China

X-ray computed tomography(XCT)has recently emerged as a powerful tool for characterizing the evolution of microstructure during phase transformation in three dimensional(3D)such as dendritic solidification of *** paper briefly reviews the recent advances in the in-situ observation of aluminium alloys,magnesium alloys and nickel-based superalloys during solidification using laboratory XCT and synchrotron X-ray *** focus is on the growth kinetics of dendrites,porosity and secondary *** addition,in-situ characterization during the loading and corrosion process is also discussed.

关键词： X-ray computed tomography(XCT) synchrotron dendrite porosity alloys

Effects of Heat Stress during Seed Filling Stage on Brassica napus Seed Oil Accumulation and Chlorophyll Fluorescence Characteristics

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Phyton-International Journal of Experimental Botany 2023年第2期92卷 333-348页

作者： Ruizhi Huang Huasheng Yu Yong Yang Heqin Liu xuelong wu Zhihong Liu Haiyan He Gengwei wu Wengjia Wang Hua Wang State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-Products Institute of Virology and BiotechnologyZhejiang Academy of Agricultural SciencesHangzhou310021China Institute of Crop Science and Nuclear Technology Utilization Zhejiang Academy of Agricultural SciencesHangzhou310021China

As global temperature rise,the threat of heat stress to rapeseed production is becoming more *** the response characteristics of two important biological pathways,oil accumulation and photosynthesis,to heat stress during *** seed filling is helpful in the genetic improvement of heat-tolerant *** effects of heat stress on seed oil accumulation and chlorophyll fluorescence characteristics of 29 *** germplasms with different oil content and environmental sensitivity,including 6 rapeseed varieties which exhibited environmentsensitive/insensitive and with high,medium or low oil content,were tested by whole plant heat stress or the in vitro silique culture *** assay exhibited similar trend on oil content of the rapeseed *** heat effect on the chlorophyll fluorescence kinetic parameters F_(v)/F_(m),ETR and Y(Ⅱ)were also *** stress significantly decreased oil content,although there was abundant genetic variation on heat tolerance among the *** analysis showed that the decrease rate of F_(v)/F_(m) of silique heat-stressed *** developing seed was positive correlative to the decrease rate of mature seed oil content of the whole plant heat-stressed rapeseed(R=0.9214,P-value<0.01).Overall,the results indicated that heat stress inhibited oil accumulation and photosynthesis in *** developing *** decrease rate of chlorophyll fluorescence parameter F_(v)/F_(m) of heat-stressed developing seed could be used as the index of heat tolerant rapeseed ***,two heat insensitive rapeseed varieties with high oil content were identified.

关键词： Brassica napus L. heat stress seed filling stage oil accumulation chlorophyll fluorescence characteristics

Development of Integrated Computational Materials Engineering(ICME)Model for Mg Alloy Design and Process Optimization

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Journal of Beijing Institute of Technology 2023年第4期32卷 422-442页

作者： Hui Su Zhifei Yan Yingchun Tian Chengpeng Xue Shuo Wang Guangyuan Tian Xinghai Yang Quan Li xuelong wu Zhongyao Li Junsheng Wang School of Materials Science and Engineering Beijing Institute of TechnologyBeijing 100081China Advanced Research Institute of Multidisciplinary Science Beijing Institute of TechnologyBeijing 100081China China North Industries Group No.52 Research InstituteBaotouInner Mongolia 014030China

Integrated computational materials engineering(ICME)has emerged to be one of the most powerful materials genome engineering(MGE)approaches in designing new materials and manufacturing processes in recent *** has successfully deployed many new products for the electronic,automotive,and aerospace *** paper reviews the current status of research on first principles in the design of high-strength Mg alloys,discusses the application of crystal plasticity finite element models to the microscale slip,twinning,microstructure morphology,texture evolution,and macroscopic forming of Mg alloys,and introduces the research progress of crystal plasticity finite element models and phase field models,meta cellular automata models and first principles coupled models respectively,around the need for multi-scale coupled simulations of Mg *** key technology obstacles of integrating the first principles,crystal plasticity finite element,and microstructure models for Mg alloys have been *** paper can provide a reference for the design of new Mg alloy compositions and the development of high-performance Mg alloys.

关键词： first-principles crystal plasticity finite elements microstructure Mg alloys

D38MSV5S非调质钢曲轴断裂分析及改进

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金属材料与冶金工程 2024年第3期52卷 3-8页

作者：柯豪胡沛锋饶晓晓赵红利蒋森彭永键吴雪龙胡一恒湖北汽车工业学院湖北十堰442002

某汽车用D38MSV5S非调质钢曲轴在行车过程中发生断裂,通过对失效曲轴的宏微观断口、化学成分、金相组织、显微硬度等检测分析。结果表明:曲轴基体组织粗大、A类夹杂物分布不均、材料偏析严重、裂纹源区条状硫化物较多等缺陷,导致曲轴早... 详细信息

某汽车用D38MSV5S非调质钢曲轴在行车过程中发生断裂,通过对失效曲轴的宏微观断口、化学成分、金相组织、显微硬度等检测分析。结果表明:曲轴基体组织粗大、A类夹杂物分布不均、材料偏析严重、裂纹源区条状硫化物较多等缺陷,导致曲轴早期疲劳断裂。通过改善锻造工艺、细化晶粒、控制硫化物形态以及优化改进曲轴的圆角滚压强化工艺,采用适当的滚压力和滚压圈数等参数,获得理想的残余压应力状态;优化滚压加工质量和加工效率,才能有效体现曲轴的轴颈感应淬火强化方式+圆角滚压复合强化效果,提高曲轴抗疲劳断裂能力,有效延长曲轴寿命。

关键词：发动机曲轴非调质钢疲劳断裂失效分析圆角滚压

低压铸造铝合金轮毂工艺参数对缩孔缺陷的影响

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铸造技术 2024年第2期45卷 163-172页

作者：李钟尧吴雪龙苗以升薛程鹏郎玉玲孔德才马小英乔海波王俊升北京理工大学机械与车辆学院北京100081 北京理工大学材料学院北京100081 中信戴卡股份有限公司河北秦皇岛066010 北京理工大学前沿交叉科学研究院北京100081

乘用车轮毂90%以上采用铝合金低压铸造工艺实现,轮毂铸造缺陷是影响其机械性能和服役安全性的主要因素之一,因此控制轮毂铸件的缺陷不仅是产品质量问题,也是关乎汽车整体的服役安全性问题。本文系统研究并总结了低压铸造工艺参数对孔洞... 详细信息

乘用车轮毂90%以上采用铝合金低压铸造工艺实现,轮毂铸造缺陷是影响其机械性能和服役安全性的主要因素之一,因此控制轮毂铸件的缺陷不仅是产品质量问题,也是关乎汽车整体的服役安全性问题。本文系统研究并总结了低压铸造工艺参数对孔洞缺陷的影响。针对低压铸造轮毂中可能产生的缩孔缩松缺陷,研究了浇注温度、模具预热温度、充型速度、保压压力等工艺参数对缩孔缺陷分布规律,发现在一定范围内,浇注温度与模具预热温度的上升,均可使金属液充型能力提高,减少缩孔缺陷;但当浇注温度或模具预热温度过高时,缩孔开始增加。在保证不发生欠充型的前提下,充型加压速度越慢,则充型过程越缓慢平稳,缩孔出现的概率越低。随着保压压力的提高,缩孔缺陷减少。

关键词：汽车轮毂低压铸造铝合金缩孔缩松有限元计算

Expression of Tibetan wild barley HvHKT1 regulates root pH,K+,and Ca2+ homeostasis and confers salt tolerance

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Expression of Tibetan wild barley HvHKT1 regulates root pH,K...