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Robust interface and excellent as-built mechanical properties of Ti–6Al–4V fabricated through laser-aided additive manufacturing with powder and wire

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International Journal of Minerals,Metallurgy and materials 2025年第1期32卷 154-168页

作者： Fei Weng Guijun Bi Youxiang Chew Shang Sui Chaolin Tan Zhenglin Du Jinlong Su Fern Lan Ng Key Laboratory for Liquid-Solid structural Evolution and Processing of materials Ministry of EducationShandong Engineering&Technology Research Center for Superhard MaterialSchool of Materials Science and EngineeringShandong UniversityJinan 250061China Institute of Intelligent Manufacturing Guangdong Academy of SciencesGuangzhou 510095China Singapore Institute of Manufacturing Technology 5 Cleantech Loop636732Singapore

The feasibility of manufacturing Ti-6Al-4V samples through a combination of laser-aided additive manufacturing with powder(LAAM_(p))and wire(LAAM_(w))was explored.A process study was first conducted to successfully circumvent defects in Ti-6Al-4V deposits for LAAM_(p) and LAAM_(w),*** the optimized process parameters,robust interfaces were achieved between powder/wire deposits and the forged substrate,as well as between powder and wire *** characterization results revealed the epitaxial prior β grains in the deposited Ti-6Al-4V,wherein the powder deposit was dominated by a finerα′microstructure and the wire deposit was characterized by lamellar α *** mechanisms of microstructure formation and correlation with mechanical behavior were analyzed and *** mechanical properties of the interfacial samples can meet the requirements of the relevant Aerospace material Specifications(AMS 6932)even without post heat *** fracture occurred within the interfacial area,further suggesting the robust *** findings of this study highlighted the feasibility of combining LAAM_(p) and LAAM_(w) in the direct manufacturing of Ti-6Al-4V parts in accordance with the required dimensional resolution and deposition rate,together with sound strength and ductility balance in the as-built condition.

关键词： laser-aided additive manufacturing powder deposition wire deposition interfacial characteristic mechanical behavior

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Direct Imaging of Molecular Orbitals of Metal Phthalocyanines on Metal Surfaces with an O2-Functionalized Tip of a Scanning Tunneling Microscope

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Nano Research 2011年第6期4卷 523-530页

作者： Zhihai Cheng Shixuan Du Wei Guo Li Gao Zhitao Deng Nan Jiang Haiming Guo Hao Tang H. J. Gao Institute of Physics Chinese Academy of Sciences RO. Box 603 Beijing 100190 China center for material elaboration and structural studies B.P. 94347 31055 Toulouse Cedex France

High-resolution scanning tunneling microscope images of iron phthalocyanine and zinc phthalocyanine molecules on Au（111） have been obtained using a functionalized tip of a scanning tunneling microscope （STM）, and show rich intramolecular features that are not observed using clean tips. Ab initio density functional theory calculations and extended Huckel theory calculations revealed that the imaging of detailed electronic states is due specifically to the decoration of the STM tip with O2. The detailed structures are differentiated only when interacting with the highly directional orbitals of the oxygen molecules adsorbed on a truncated, [111]-oriented tungsten tip. Our results indicate a method for increasing the resolution in generic scans and thus, have potential applications in fundamental research based on high-resolution electronic states of molecules on metals, concerning, for example, chemical reactions, and catalysis mechanisms.

关键词： High-resolution scanning tunneling microscope (STM) imaging functionalized STM tip metal phthalocyanines molecular orbital density functional theory calculation

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Effect of Heat Input on Cleavage Crack Initiation of Simulated Coarse Grain Heat-affected Zone in Microalloyed Offshore Platform Steel

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Journal of Iron and Steel Research International 2016年第10期23卷 1086-1095页

作者： Feng LU Guang-ping CHENG Feng CHAI Tao PAN Zhong-ran SHI Hang SU Cai-fu YANG School of material Science and Engineering Anhui University of Technology Department of structural Steel Central Iron and Steel Research Institute

The combined effects of martensite-austenite（MA）constituent and pearlite colony on cleavage crack initiation in the simulated coarse-grained heat-affected zone（CGHAZ）of V-N-Ti microalloyed offshore platform steel under different heat inputs were *** results of welding simulation,instrumented impact test,and quantitative analysis indicated that the size of the MA constituent decreased with the increase in cooling time,and by contrast,the size of the pearlite colony *** to Griffith theory,the critical sizes of cleavage microcracks were *** the increase of cooling time,the calculated microcrack size could be characterized by the size of the MA constituent first,and then fitted with the size of the pearlite ***,the calculated microcrack size variation was opposite to the microcrack initiation *** phenomenon is probably due to the combined effects of the MA constituent and pearlite colony with increasing the cooling time of the specimen′s temperature from800 to 500 ℃.

关键词： simulated coarse-grained heat-affected zone martensite-austenite constituent pearlite colony cleavage fracture V-N-Ti microaltoying

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Effect of modifying matrix microstructures and nanosized precipitates on strengthening mechanisms and ductile-to-brittle-transitiontemperature in a 1000 MPa Ni-Cr-Mo-Cu steel

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Journal of Iron and Steel Research International 2022年第8期29卷 1257-1276页

作者： Fei Zhu Li Yang Feng Chai Xiao-bing Luo Cai-fu Yang Zheng-yan Zhang Department of structural Steels Central Iron and Steel Research InstituteBeijing 100081China material Digital R&D center China Iron and Steel Research Institute GroupBeijing 100081China

A superior combination of yield strength(1001 MPa)and-20℃ impact toughness(166 J)was obtained in Nb-V-Timicroalloyed Ni-Cr-Mo-Cu steel treated by direct quenching and tempering route(DQT).The tested steels treated by DQT route and re-austenitization and tempering route(QT)were compared with each other in terms of mechanical properties and microstructures characterized by optical microscopy,transmission electron microscopy,X-ray diffraction,electron back-scattered diffraction method and so *** and Vickers hardness of the tested steel treated by the above two routes vary with isothermal aging temperature(400-600℃),shown as under-aged state,peak-aged state and overaged *** DQT specimens show higher strength and Vickers hardness than QT specimens with the same aging ***,the largest difference of yield strength between DQT and QT specimens was shown in DQT600 and QT600 ***600 or QT600 specimens refers to direct quenched(DQ)or quenched(Q)specimens isothermally aged at 600℃.The main disparities in quenched microstructure between DQ and Q specimens are mainly in morphology of prior austenite grains,dislocation density of martensite matrix and solution amount of Nb and Mo elements dissolving in martensite matrix,which play key roles in affecting microstructure and mechanical properties of DQT and QT *** dislocation density of matrix and finer average diameter of both MC(M is any combination of Nb,Mo and V)and Cu-rich particles were shown in DQT600 specimens than in QT600 *** from dislocations and nanosized MC and Cu-rich particles mainly leads to the largest difference of yield strength between DQT600 and QT600 *** addition,strong dislocation strengthening and precipitation strengthening in DQT600 specimen also elevated its ductile-to-brittle-transition-temperature,compared with QT600 specimen.

关键词： Cu-bearing high-strength low-alloy steel Direct quenching Nanosized precipitate Strengthening Ductile-to-brittle-transition-temperature

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Influence of Extrusion Speed on the Microstructure Evolution, Interface Bonding and Mechanical Response of Mg MB26/Al 7075 Composite Rod

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Acta Metallurgica Sinica(English Letters) 2019年第2期32卷 253-262页

作者： Yu Chen Rui Zhang Tao Zhou Li Hu Jian Tu Lai-Xin Shi Yan Zhi Li-Wei Lu Qiang Chen Ben-Hong Liao Lei Liu Wen-Jun Ge Jing Xiao Ming-Bo Yang College of material Science and Engineering Chongqing University of Technology Institute of Light Metal structural materials Hunan University of Science and Technology Southwest Technology and Engineering Research Institute Precision Forming Integrated Manufacturing Technology of Collaborative Innovation center

The Mg MB26/Al 7075 composite rod,in which Mg MB26 serves as the sleeve and Al 7075 serves as the core,is fabricated via the process of *** influence of extrusion speed on the microstructure evolution,interface bonding and mechanical response of the Mg MB26/Al 7075 composite rod is *** results show that the typical extrusion texture of Mg sleeve does not change during co-extrusion;however,the average grain size in the Mg sleeve slightly changes from 1.57 lm in the case of extrusion speed of 0.3 mm/s to 2.78 lm in the case of extrusion speed of2.1 mm/*** thickness of interface transition layer increases significantly from 5.5 to 50 lm,and therefore,the interface bonding becomes deteriorative with increasing extrusion speed;in particular,many cavities emerge in the case of 1.2 and2.1 mm/s.

关键词： MB26/7075 composite rod Extrusion speed Microstructure evolution Interface bonding Mechanical response

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A 3-D Time-Domain Coupled Model for Nonlinear Waves Acting on A Box-Shaped Ship Fixed in A Harbor

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China Ocean Engineering 2011年第3期25卷 441-456页

作者：王大国邹志利 THAM Leslie George center for material Failure Modeling Research Dalian University The State Key Laboratory of Coastal and Offshore Engineering Department of Civil EngineeringDalian University of Technology Department of Civil and structural Engineering The University of Hong Kong

A 3-D time-domain numerical coupled model is developed to obtain an efficient method for nonlinear waves acting on a box-shaped ship fixed in a harbor. The domain is divided into the inner domain and the outer domain. The inner domain is the area beneath the ship and the flow is described by the simplified Euler equations. The remaining area is the outer domain and the flow is defined by the higher-order Boussinesq equations in order to consider the nonlinearity of the wave motions. Along the interface boundaries between the inner domain and the outer domain, the volume flux is assumed to be continuous and the wave pressures are equal. Relevant physical experiment is conducted to validate the present mode/and it is shown that the numerical results agree with the experimental data. Compared the coupled model with the flow in the inner domain governed by the Laplace equation, the present coupled model is more efficient and its solution procedure is simpler, which is particularly useful for the study on the effect of the nonlinear waves acting on a fixed box-shaped ship in a large harbor.

关键词： nonlinear waves coupled model Boussinesq equations Euler equations

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A Time-Domain Coupled Model for Nonlinear Wave Forces on A Fixed Box-Shaped Ship in A Harbor

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China Ocean Engineering 2010年第1期24卷 41-56页

作者：王大国邹志利谭国焕刘霞 center for material Failure Modeling Research Dalian University The State Key Laboratory of Coastal and Offshore Engineering Department of Civil EngineeringDalian University of Technology Department of Civil and structural Engineering The University of Hong Kong

A 2-D time-domain numerical coupled model is developed to obtain an efficient method for nonlinear wave forces on a fixed box-shaped ship in a harbor. The domain is divided into an inner domain and an outer domain. The inner domain is the area beneath the ship and the flow is described by the simplified Euler equations. The other area is the outer domain and the flow is defined by the higher-order Boussinesq equations in order to consider the nonlinearity of the wave motions. Along the interface boundaries between the inner domain and the outer domain, the volume flux is assumed to be continuous and the wave pressures are equal. Relevant physical experiment is conducted to validate the present model. It is shown that the numerical results agree with the experimental data. Compared with the coupled model with the flow in the inner domain governed by the Laplace equation, the present coupled model is more efficient and its solution procedure is more simple, which is particularly useful for the study on the effect of the nonlinear wave forces on a fixed box-shaped ship in a large harbor.

关键词： coupled model wave forces Boussinesq equations Euler equations

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Effect of Aging Treatment on Precipitation Behavior and Mechanical Properties of a Novel Aluminum–Lithium Alloy

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Acta Metallurgica Sinica(English Letters) 2015年第6期28卷 671-677页

作者： Hua-Guan Li Juan Ling Yi-Wei Xu Zhong-Gang Sun Hong-Bing Liu Xing-Wei Zheng Jie Tao College of material Science and Technology Nanjing University of Aeronautics and Astronautics Jiangsu Key Laboratory of Advanced structural materials and Application Technology Shanghai Aircraft Manufacturing Company Limited

In this work, the microstructure and precipitation phases were primarily characterized by transmission electron microscopy. The mechanical properties were evaluated by tensile and tear test. The results indicated that the samples aged at 145 ℃ for 45 h or 155 ℃ for 30 h possessed a preferable combination of strength and plasticity, owing to the precipitation of well-dispersed T1 （A12CuLi） phases （diameter 〈 150 nm）. However, aging at more than 165 ℃ caused an obvious size growth of T1 plates, leading to the quick reduction in plasticity and toughness. Furthermore, the high Cu/Li ratio resulted in distinct precipitation features, including a shorter incubation time of T1 phase and the aggravated precipitate-free zones.

关键词： Aluminum-lithium alloy Aging treatment Fracture toughness Microstructure

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Analysis of material flow and heat transfer in friction stir welding of aluminium alloys

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China Welding 2013年第1期22卷 6-10页

作者：宿浩武传松陈茂爱 MOE Key Laboratory for Liquid-Solid structural Evolution and material Processing and Institute of Malerial Joining Shandong University Jinan 250061

A three-dimensional *** element model is established based on computational fluid mechanics. The material during the welding process is considered as non-Newtonian fluid abided by Norton-Hoff constitutive law, and viscous dissipation is assumed as the unique heat source. The model is used to numerically simulate the material flow and heat transfer in friction stir welding, and capture some useful process characteristics, .such as heat generation, temperature distribution and ***; besides, the velocity field is used to calculate streamlines of material flow, and the dimension of the deformation zone is measured.

关键词： friction stir welding material flow heat transfer modeling

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Study on micro-texture and skid resistance of aggregate during polishing

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Frontiers of structural and Civil Engineering 2017年第3期11卷 346-352页

作者： Zhenyu QIAN Lingjian MENG National center for material Service Safety University of Science and Technology Beijing Beijing 100083 China

The skid resistance performance of pavement is closely related to the micro-texture of pavement aggregate, while there is very few research on the relationship between micro-texture and the skid resistance. In this paper, the optical microscope is used to acquire the surface morphology of three types of aggregates including basalt, limestone and red sandstone respectively, where a total of 12 indicators are developed based on the surface texture information. The polishing effect on aggregate is simulated by Wehner/Schulze （W/S） device, during the polishing procedure, the skid resistance are measured by British Pendulum Tester （BPT）. Based on the results of independent T-test and the polishing resistance analysis, it shows that the surface texture of basalt is significantly different between limestone and red sandstone. Three indicators including the average roughness （Ra）, the kurtosis of the surface （Sku） and the mean summit curvature （Ssc） are selected to describe the characteristics of aggregate micro-texture based on the correlation analysis. The contribution of micro-texture to the skid resistance can be described with the secondary polynomial regression model by these indicators.

关键词： skid resistance of pavement micro-texture aggregates polishing test

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