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Variation of mechanical properties and microstructure of hot-rolled AA2099 Al-Li alloy induced by the precipitation during preheating process

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Journal of Materials Science & Technology 2022年第15期110卷 198-209页

作者： Fei Guo weijiu huang Xusheng Yang Haipeng Dong Hang Yu Qiuyu Chen Li Hu Luyao Jiang College of Materials Science and Engineering Chongqing University of TechnologyChongqing 400054China College of Materials Science and Engineering Chongqing University of Arts and ScienceChongqing 402160China Chongqing Materials Research Institute Co. LtdChongqing 400707China

Preheating is the first step for thermal-mechanical processing of the materials. Several preheating schedules were designed based on industrial manufacturing to explore their effect on the microstructure and mechanical properties of AA2099 Al-Li alloy during the following hot rolling. The results show that the mechanical properties of as-rolled sheets are quite sensitive to preheating. Various types of secondary phases, including δ', T1 and T2 phases, were precipitated during the heating process. The difference among precipitates is the main reason to induce the variation of mechanical properties for as-rolled sheets. A rapid heating rate gave rise to the precipitation of δ' phase, which largely promoted yield stress and ultimate tensile strength in as-rolled sheets. T1 phase was more favorable in the preheating with a holding period at 150–250 °C, which caused a moderated strain hardening behavior. Precipitates formed during preheating induced different slip behaviors in the following deformation. The coexistence of T1 and δ' phase could restrict planar slip, which inhibited the formation of the shear band. The difference in the activity of non-octahedral slips and planar slips determined the strain hardening effect, which should be the reason for the variation of mechanical properties of as-rolled sheets.

关键词： Aluminum-lithium alloys Preheating Precipitation Mechanical properties Shear band

Influence of pre-stretching on the tensile strength,fatigue properties and the in-plane anisotropy in Al-Cu-Li alloy AA2099

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Journal of Materials Science & Technology 2023年第14期145卷 249-259页

作者： Xianghui Zhu Xusheng Yang weijiu huang Weiyi Qiu Xin Wang Fei Guo Li Hu Miao Gong College of Materials Science and Engineering Kunming University of Science and TechnologyKunming 650093China College of Materials Science and Engineering Chongqing University of Arts and SciencesChongqing 402160China College of Materials Science and Engineering Chongqing University of TechnologyChongqing 400044China

The influence of pre-stretching prior to artificial aging on microstructure,tensile properties,and fatigue behavior of AA2099-T8 sheets was *** results showed that increased pre-strain level from 1%to 6%resulted in a more uniform distribution and increasing density of the T_(1)*** localized plastic deformation during pre-stretching led to the formation of dense precipitation bands(DPBs)and precipitation free bands(T_(1)-PFBs)in the sheets with the 1%*** non-uniform distribution of the T_(1)phase with T_(1)-PFBs and DPBs resulted in a decrement in elongation and a strong in-plane anisotropy of tensile *** appropriate level of pre-strain should be executed aiming to improve elongation and reduce the tensile anisotropy by promoting a uniform distribution of the T_(1)***-plane anisotropy of yield strength due to the presence of DPBs and T_(1)-PFBs was quantitatively analyzed by the modified Hall-Petch *** results of the calculation for the modified model showed good agreement with the *** addition,resistances of fatigue crack propagation(FCP)in the same orientation were gradually decreased with the increment of pre-strain due to the increment in yield strength and more uniform distribution of the T_(1)*** the in-plane anisotropy of FCP resistance,the main reasons were the development of rough fracture surfaces and the transgranular fracture modes in L-T orientation.

关键词： Aluminum-lithium alloys Precipitation Mechanical properties Fatigue crack propagation

Evolution of surface microstructure of Cu-50Cr alloy treated by high current pulsed electron beam

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Science China(Technological Sciences) 2015年第3期58卷 462-469页

作者： CHAI LinJiang ZHOU ZhiMing XIAO ZhiPei TU Jian WANG YaPing huang weijiu College of Materials Science and Engineering Chongqing University of Technology School of Science Xi'an Jiaotong University

A Cu-50Cr alloy was treated by the high current pulsed electron beam(HCPEB)at 20 and 30 ke V with pulse numbers ranging from 1 to *** morphologies and microstructures of specimens before and after the treatments were investigated by employing scanning electron microscopy and X-ray *** show that the HCPEB technique is able to induce remarkable surface modifications for the Cu-50Cr *** in Cr phases appear even after one-pulse treatment and their density always increases with the pulse *** reason for these cracks is attributed to quasi-static thermal stresses accumulated along the specimen *** with typical morphologies are formed due to the dynamic thermal field induced by the HCPEB and they are found to prefer the sites near cracks or boundaries between neighboring Cr *** microstructural characteristic produced by the HCPEB is the fine Cr spheroids,which are determined to be due to occurrence of liquid phase separation in the Cu-50Cr ***,a general microstructural evolution profile that incorporates various HCPEB-induced surface features is tentatively outlined.

关键词： Cu-Cr alloy microstructure surface modification electron beam

Concurrent inheritance of microstructure and texture after slow β→α cooling of commercially pure Zr

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Science China(Technological Sciences) 2016年第11期59卷 1771-1776页

作者： CHAI LinJiang LUAN BaiFeng CHEN BaoFeng YANG HuiLong LIU Qing huang weijiu College of Materials Science and Engineering Chongqing University College of Materials Science and Engineering Chongqing University of Technology Institute for Materials Research Tohoku University

A rolled and recrystallized commercially pure Zr sheet was β-solution treated and then cooled at two rates, i.e. air cooling(AC)and furnace cooling(FC). Microstructures and textures of original and β-cooled specimens were characterized by use of electron channeling contrast imaging, electron backscatter diffraction and X-ray diffraction techniques. Results reveal a novel phenomenon, i.e. the concurrent inheritance of microstructure and texture in the FC specimen cooled at a very slow rate. In contrast, for the AC specimen with faster cooling, typical lamellar α phases are obtained with relatively scattered *** on comparatively crystallographic and thermodynamic analyses, reasons accounting for microstructure and texture differences in both cases are discussed, highlighting the significant role played by the variant selection behavior. It is postulated that increasing cooling rates should be more feasible to change the transformed texture in Zr materials.

关键词： Zr phase transformation texture microstructure electron backscatter diffraction

Typical Microstructural Characteristics of Ti–5Al–5Mo–5V–3Cr–1Fe Metastable β Ti Alloy Forged in α + β Region

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Acta Metallurgica Sinica(English Letters) 2020年第12期33卷 1601-1608页

作者： Zhiying Zheng Linjiang Chai Kang Xiang weijiu huang Yongfeng Wang Liangliang Liu Lin Tian College of Materials Science and Engineering Chongqing University of TechnologyChongqing 400054China College of Materials Science and Engineering Chongqing University of Arts and SciencesChongqing 402160China Chongqing Kingsley Aeronautical Material Technology Co.Ltd Chongqing 404100China

In this study,typical microstructural characteristics of a metastableβTi alloy(Ti–5Al–5Mo–5V–3Cr–1Fe)forged in a dual-phase region(strain of 54%at 820℃)were investigated in detail by the combined use of X-ray diff raction,energy dispersive spectroscopy,electron channeling contrast imaging and electron backscatter diff raction *** show that the microstructure of the forged alloy is composed of bulkαgrains,αplates andβ*** bulkαgrains correspond to retained primaryαphase(αp,average grain size^2.4μm),while theαplates are secondaryαphase(αs,width^70 nm)precipitated from theβmatrix during air *** forging,theβmatrix experiences dynamic recovery with many subgrains and signifi cant orientation gradients *** of the orientation relationship between theαandβphases show that the Burgers orientation relationship is not maintained between someα_p andβphases,which should be related to thermal deformation-induced changes of their *** contrast,all of theαs plates are found to maintain well the Burgers orientation relationship with theβphase.

关键词： Metastableβ Ti alloy α+βforging Dynamic recovery Orientation relationship Electron backscatter diffraction(EBSD)

Tribological Performances of Fatty Acyl Amino Acids Used as Green Additives in Lubricating Oil

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China Petroleum Processing & Petrochemical Technology 2010年第3期12卷 49-53页

作者： Chen Boshui Wang Jiu Fang Jianhua huang weijiu Sun Xia Yu Ying Dept. of Petrochemistry Logistical Engineering University Chongqing 401311 College of Material Engineering Chongqing University of Science and Technology Chongqing 400050 College of Bioengineering Chongqing University of Science and Technology Chongqing 400050

The friction and wear characteristics of lauroyl glutamine, lauroyl glycine and lauroyl alanine, used as green additives in HVI 350 mineral lubricating oil, were evaluated on a four-ball tribotester. The morphologies and chemical species of the worn surfaces were analyzed by scanning electron microscope （SEM） and X-ray photoelectron spectroscope （XPS）, respectively. The test results indicated that the three fatty acyl amino acids could effectively improve the anti-wear and friction-reducing abilities of the HVI 350 mineral oil. The improvement in anti-wear and friction-reducing abilities of the mineral oil by the related amino acids was mainly ascribed to the formation of a composite boundary lubrication film due to the adsorption of amino acids on the friction surfaces.

关键词： fatty acyl amino acid mineral lubricating oil friction wear

晶界特征对AA2099铝锂合金疲劳加载分层断裂影响探究

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材料导报 2022年第10期36卷 124-128页

作者：仇伟夷祝祥辉黄伟九杨绪盛汪鑫重庆理工大学材料科学与工程学院重庆文理学院新材料技术研究院昆明理工大学材料科学与工程学院

通过电子背散射衍射及背散射电子等成像分析手段，从晶体学织构、晶界特征等角度研究了热处理对AA2099铝锂合金疲劳加载时分层断裂的影响机理。研究结果表明：AA2099铝锂合金疲劳加载时分层断裂多发生于平直的高角晶界处，断裂区域晶粒... 详细信息

通过电子背散射衍射及背散射电子等成像分析手段，从晶体学织构、晶界特征等角度研究了热处理对AA2099铝锂合金疲劳加载时分层断裂的影响机理。研究结果表明：AA2099铝锂合金疲劳加载时分层断裂多发生于平直的高角晶界处，断裂区域晶粒通常为Brass取向，且裂纹扩展方向平行于晶粒的{110}面。分层断裂现象与晶界曲折程度有直接关系，相比于T81试样和T83试样，固溶态(ST)试样晶界更为曲折，相对更难发生分层断裂。预拉伸量的增加使T83试样与T81试样的晶界析出相形貌迥异；循环载荷作用过程中，T83试样粗大颗粒状晶界析出相处的界面脱粘加剧了分层断裂，因此分层断裂严重程度为：T83试样>T81试样>ST试样。

关键词：铝锂合金晶体学织构晶界特征分层断裂

Effect of Lauroyl Glutamine on Biodegradation of Lubricating Oil and Simulation of Biodegradation Kinetics

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Engineering（科研） 2010年第11期2卷 926-929页

作者： Boshui Chen Jiang Wu Jianhua Fang weijiu huang Jiu Wang 不详

Small amount of lauroyl glutamine was incorporated into HVI 350 mineral lubricating oil and the biodegradabilities of neat oil and the formulated oil in soils were evaluated. Thereafter, the biodegradation rate equations for the two lubricating oils were simulated based on the exponential model. The results indicated that lauroyl glutamine effectively promoted biodegradation of HVI 350 mineral lubricating oil. Under given test conditions, the exponential model well fitted the biodegradation of lubricating oils in soils. The biodegradation rate equation for HVI 350 mineral lubricating oil can be described as ln(St/S0) = –0.0155t, while that for the oil formulated with lauroyl glutamine as ln(St/S0) = –0.0235t. The biodegradation half-lives of neat oil and the formulated oils were 44.72 days and 29.50 days, respectively.

关键词： Lauroyl Glutamine Lubricating Oil Biodegradation Kinetics

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可促进润滑油生物降解的新型润滑添加剂研究

润滑与密封 2009年第11期34卷 5-8页

作者：黄伟九重庆理工大学材料科学与工程学院重庆400050

设计并合成了N-油酰基丝氨酸添加剂,运用红外光谱表征了其结构,通过摩擦学和生物降解实验考察了其在HVI350矿物油中的摩擦学和生物降解性能,并探讨了其摩擦学和促进润滑油生物降解的作用机制。研究表明:N-油酰基丝氨酸能有效提高矿物基... 详细信息

设计并合成了N-油酰基丝氨酸添加剂,运用红外光谱表征了其结构,通过摩擦学和生物降解实验考察了其在HVI350矿物油中的摩擦学和生物降解性能,并探讨了其摩擦学和促进润滑油生物降解的作用机制。研究表明:N-油酰基丝氨酸能有效提高矿物基础油的减摩抗磨能力,并能显著提高矿物基础油的生物降解性能,是一种潜在的环境友好润滑添加剂。

关键词：生物降解润滑添加剂摩擦学环境友好