74 results on '"Xinqi Yang"'
Search Results
2. An empirical analysis of vulnerability information disclosure impact on patch R&D of software vendors
- Author
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Qiang Xiong, Shuai Lian, Zhangying Zeng, Runxin He, Binxin Zhu, and Xinqi Yang
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Statistics and Probability ,Artificial Intelligence ,General Engineering - Abstract
The vulnerability patch R&D has become an important part of information security governance. An effective collaboration with software vendors in patch R&D is of great significance to reduce the existence time of information security risks. This works aims to explore the relationship between vulnerability information disclosure and patch R&D of software vendors. The data regarding the vulnerability and software vendors is gathered from third-party vulnerability sharing platforms, including (China’s national information security vulnerability database, CNNVD) and Tianyacha.com. Based on the theory of organizational information processing, linear regression model and Cox proportional risk regression model are built for appropriately addressing the research questions. The results show that the vulnerability disclosure of the third-party sharing platform can improve the patch R&D probability of software vendors. The information processing requirements, such as vulnerability information attention, vulnerability score and whether vulnerabilities are disclosed in advance accelerate the vulnerability patch R&D. The enterprise information processing capability indicators, including the industry dependence of software product customers and the staff size of software vendors accelerate the patch R&D. The number of products affected by the vulnerabilities and the number of software copyrights of software vendors have no significant impact on patch R&D.
- Published
- 2023
3. Softening behavior of stationary shoulder friction stir welded joint for thick-plate Al–Li–Cu alloy
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Chao Gu, Xinqi Yang, Wenshen Tang, Ting Luo, and Ruilin Wang
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Biomaterials ,Metals and Alloys ,Ceramics and Composites ,Surfaces, Coatings and Films - Published
- 2022
4. Signal Game Analysis between Software Vendors and Third-Party Platforms in Collaborative Disclosure of Network Security Vulnerabilities
- Author
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Qiang Xiong, Yifei Zhu, Zhangying Zeng, and Xinqi Yang
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Multidisciplinary ,General Computer Science ,Article Subject - Abstract
The global network threat is becoming more and more serious, and network security vulnerability management has become one of the critical areas in the national information security emergency system construction. To guide the third-party sharing platforms regarding network security vulnerability management, this work constructs a signal game model comprising third-party vulnerability sharing platforms and software vendors for vulnerability collaborative disclosures. In addition, we analyze the game strategy selection and its influencing factors. The results show that there are two perfect Bayesian equilibria, including separation equilibrium and mixed equilibrium, due to the incomplete lines of information disclosure. The equilibrium state is mainly based on the compression time of the protection period and the existence ratio of the software vendors who develop the patches in the market. This work puts forward some suggestions in terms of the protection period, reputation loss, and relevant laws and regulations.
- Published
- 2023
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5. Multiscale Progressive Complementary Fusion Network for Fine-Grained Visual Classification
- Author
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Jingsheng Lei, Xinqi Yang, and Shengying Yang
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General Computer Science ,General Engineering ,General Materials Science ,Electrical and Electronic Engineering - Published
- 2022
6. Microstructure heterogeneity and mechanical properties of Mg-Gd-Y-Zr alloy fabricated by force-controlled additive friction stir deposition
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Ting Luo, Wenshen Tang, Ruilin Wang, Shiwei Wang, Lv Xiao, and Xinqi Yang
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Mechanics of Materials ,Mechanical Engineering ,General Materials Science ,Condensed Matter Physics - Published
- 2023
7. Vascular Disruptive Hydrogel Platform for Enhanced Chemotherapy and Anti-Angiogenesis through Alleviation of Immune Surveillance
- Author
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Fasheng Li, Xinmei Shao, Dehui Liu, Xiaogang Jiao, Xinqi Yang, Wencai Yang, and Xiaoyan Liu
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anti-angiogenesis therapy ,vascular disruption ,immunogenic cell death ,immune surveillance ,Pharmaceutical Science - Abstract
Patients undergoing immunotherapy always exhibit a low-response rate due to tumor heterogeneity and immune surveillance in the tumor. Angiogenesis plays an important role in affecting the status of tumor-infiltrated lymphocytes by inducing hypoxia and acidosis microenvironment, suggesting its synergistic potential in immunotherapy. However, the antitumor efficacy of singular anti-angiogenesis therapy often suffers from failure in the clinic due to the compensatory pro-angiogenesis signaling pathway. In this work, classic injectable thermosensitive PLGA-PEG-PLGA copolymer was used to construct a platform to co-deliver CA4P (vascular disruptive agent) and EPI for inducing immunogenic cell death of cancer cells by targeting the tumor immune microenvironment. Investigation of 4T1 tumor-bearing mouse models suggests that local administration of injectable V+E@Gel could significantly inhibit the proliferation of cancer cells and prolong the survival rate of 4T1 tumor-bearing mouse models. Histological analysis further indicates that V+E@Gel could effectively inhibit tumor angiogenesis and metastasis by down-regulating the expression of CD34, CD31, MTA1 and TGF-β. Moreover, due to the sustained release kinetics of V+E@Gel, its local administration relieves the immune surveillance in tumor tissues and thus induces a robust and long-lasting specific antitumor immune response. Overall, this work provides a new treatment strategy through the mediation of the tumor immune microenvironment by vascular disruption to fulfill enhanced chemotherapy and immunotherapy.
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- 2022
8. Atomic optical spatial mode extractor for vector beams based on polarization-dependent absorption
- Author
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Hong Chang, Xin Yang, Jinwen Wang, Yan Ma, Xinqi Yang, Mingtao Cao, Xiaofei Zhang, Hong Gao, Ruifang Dong, and Shougang Zhang
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General Physics and Astronomy - Abstract
Vector beams with spiral phase and spatially varying polarization profiles have many applications from optical micromanipulation to materials processing. Here, we propose and demonstrate an atomic spatial mode extracting scheme for the vector beam based on polarization-dependent absorption in the atom vapor. By employing the linear polarization pump beam which induces polarization sensitive absorption in the atomic ensemble, a counter-propagated weak probe vector beam is extracted by spatial absorption, and extracted part still maintains the original polarization and the vortex phase. The topological charges of the extracted mode are verified by interfering with the Gaussian beam, and it can be found that the orbital angular momentum is conserved in the extracting process. Our work will have potential applications in non-destructive spatial mode identification, and is also useful for studying higher-dimensional quantum information based on atomic ensembles.
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- 2023
9. Interfacial grain structure, texture and tensile behavior of multilayer deformation-based additively manufactured Al 6061 alloy
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Wenshen Tang, Xinqi Yang, Chaobo Tian, and Yongsheng Xu
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Mechanics of Materials ,Mechanical Engineering ,General Materials Science ,Condensed Matter Physics - Published
- 2023
10. Effect of rotation speed on microstructure and mechanical anisotropy of Al-5083 alloy builds fabricated by friction extrusion additive manufacturing
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Wenshen Tang, Xinqi Yang, Chaobo Tian, and Chao Gu
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Mechanics of Materials ,Mechanical Engineering ,General Materials Science ,Condensed Matter Physics - Published
- 2022
11. Numerical and experimental investigation on friction stir welding of Ti- and Nb-modified 12 % Cr ferritic stainless steel
- Author
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Xinqi Yang, Wenshen Tang, Shengli Li, Bo Du, and Huijun Li
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0209 industrial biotechnology ,Toughness ,Materials science ,Strategy and Management ,Metallurgy ,02 engineering and technology ,Welding ,Management Science and Operations Research ,021001 nanoscience & nanotechnology ,Microstructure ,Industrial and Manufacturing Engineering ,law.invention ,020901 industrial engineering & automation ,law ,Ferrite (iron) ,Martensite ,Dynamic recrystallization ,Friction stir welding ,0210 nano-technology - Abstract
A friction stir butt-welded Ti- and Nb-modified 12 % Cr ferritic stainless steel joint without any defects was successfully produced under low welding heat input. The welding heat cycles, temperature profiles, and degree of plastic deformation during welding were quantitatively evaluated based on the results of a rigid-viscoplastic thermo-mechanically coupled model. Microstructure development in the stir zone (SZ) and thermo-mechanically affected zone (TMAZ) was studied and comparatively analyzed. A fine duplex microstructure containing nearly 62.9 % martensite and 37.1 % ferrite was obtained in the SZ. Undissolved nanometer-sized precipitates during welding played a crucial role in grain refinement in the weld. Retardation of dynamic recrystallization (DRX) occurred in the SZ, and the recrystallized grains were no more than 8% of the materials. The dynamic recovery and continuous DRX experienced by the ferrite grains in the TMAZ of the advancing side were more intense than those on the retreating side, leading to a higher amount of high-angle boundaries and a 20.8 % reduction in dislocation density. The hardness and strength in the SZ apparently increased owing to refined grains and phase transformation. Both the heat-affected zone with a fully ferritic structure and the SZ exhibited superior low-temperature toughness.
- Published
- 2020
12. Effect of microstructure heterogeneity on the mechanical properties of friction stir welded reduced activation ferritic/martensitic steel
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Wenshen Tang, Xinqi Yang, Napat Vajragupta, Shengli Li, Aleksander Kostka, Hao Wang, Abhishek Biswas, and Alexander Hartmaier
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Materials science ,Friction stir welding ,Mechanical Engineering ,Metals and Alloys ,Welding ,Condensed Matter Physics ,Microstructure ,Reduced activation ferritic/martensitic steel ,Indentation hardness ,Martensitic microstructure ,law.invention ,Electron backscatter diffraction orientation analysis ,Mechanics of Materials ,law ,Martensite ,Geometrically necessary dislocations ,General Materials Science ,Austenite reconstruction ,Dislocation ,Composite material ,Electron backscatter diffraction - Abstract
The microhardness distribution in the different zones of a friction stir welded reduced activation ferritic/martensitic steel has been investigated and correlated to the hierarchical martensitic microstructure in the respective zones, characterized by electron backscatter diffraction orientation analysis. It is found that the variation of prior austenite grain size, packet size, and block width in different subzones is influenced by the peak temperature and effective strain rate during the friction stir welding process. The distribution of the microhardness correlates directly with the geometrically necessary dislocation density observed in the different zones.
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- 2022
13. Influence of Microstructure and Texture on Mechanical and Corrosion Properties in SSFSWed Joints of Thick-Plate AZ31B Alloy
- Author
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Dawei Wang, Xinqi Yang, Wenshen Tang, and Yongsheng Xu
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History ,Polymers and Plastics ,Business and International Management ,Industrial and Manufacturing Engineering - Published
- 2022
14. Characteristics of Friction Plug Joints for AA2219-T87 FSW Welds
- Author
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Zhuanping Sun, Xinqi Yang, and Shuxin Li
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AA2219-T87 aluminum alloy ,fiction plug welding ,plug and plate hole ,mechanical property ,microstructure ,local strength ,General Materials Science - Abstract
In this study, Friction plug welding (FPW) for 8 mm thickness AA2219-T87 sheets were carried out, and defect-free joints were obtained. The geometric size of plug and plate hole, rotational speed and welding force exhibit significant effects on the weld formation. Meanwhile, it is concluded that significant inhomogeneity of microstructure and mechanical properties exists in FPW joints. The recrystallization zone has the highest mechanical properties owing to the fine equiaxed grains and uniformly distributed θ precipitates. The entire plug, thermo-mechanically affected zone and nugget thermo-mechanically affected zone closed to the bonding interface are significantly softened due to the deformation of the grains and θ’ precipitate dissolution. The ultimate tensile strength (UTS) and elongation of the FPW joints can reach 359 MPa and 7.3% at 77 K and 305 MPa and 5% at 298 K, respectively.
- Published
- 2021
15. Semantic interaction learning for fine‐grained vehicle recognition
- Author
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Jingjing Zhang, Jingsheng Lei, Shengying Yang, and Xinqi Yang
- Subjects
Computer Graphics and Computer-Aided Design ,Software - Published
- 2021
16. Heat transfer between occupied and unoccupied zone in large space building with floor-level side wall air-supply system
- Author
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Chunxiao Su, Haidong Wang, Yi Wang, Xin Wang, and Xinqi Yang
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business.industry ,Airflow ,Cooling load ,0211 other engineering and technologies ,02 engineering and technology ,Building and Construction ,Heat transfer coefficient ,Mechanics ,Computational fluid dynamics ,Division (mathematics) ,Potential energy ,021105 building & construction ,Heat transfer ,Thermal ,Environmental science ,021108 energy ,business ,Energy (miscellaneous) - Abstract
The air supply terminal located at the floor level attached to side-wall is widely used in large space buildings, leading to potential energy saving as well as significant vertical thermal stratification. The cooling load calculation of such system is challenging, especially the calculation of the load gained from unoccupied zone. This paper adopts experiment and computational fluid dynamics (CFD) methods to study the heat transfer upward and downward across the stratified surface in large space building with floor-level side wall air-supply system. Five experimental cases with different heat source power and exhaust airflow ratios are performed to study their effects on the indoor thermal environment. We investigate the same cases in CFD and verify the result of vertical temperature distribution and cooling load components. As a critical parameter in evaluating the thermal stratification environment of large space building, the inter-zonal heat transfer coefficient Cb is emphatically discussed. By comparing the Cb value obtained through the two methods, the accuracy of the microscopic method is verified by the heat balance method. The results show that the Cb value is mainly affected by the zonal division and air distribution, but less prominently by exhaust airflow ratio and heat source in the occupied zone.
- Published
- 2020
17. Microstructure and properties of CLAM/316L steel friction stir welded joints
- Author
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Huijun Li, Shengli Li, Wenshen Tang, and Xinqi Yang
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Austenite ,0209 industrial biotechnology ,Materials science ,Metals and Alloys ,02 engineering and technology ,Welding ,Microstructure ,Indentation hardness ,Industrial and Manufacturing Engineering ,Computer Science Applications ,law.invention ,020303 mechanical engineering & transports ,020901 industrial engineering & automation ,0203 mechanical engineering ,law ,Modeling and Simulation ,Martensite ,Ultimate tensile strength ,Ceramics and Composites ,Composite material ,Joint (geology) ,Softening - Abstract
Defect-free welded joints were obtained by placing 316 L stainless steel at the retreating side (case 1) and the advancing side (case 2) of friction stir welds when joining China low activation martensitic (CLAM) steel to 316 L steel. Quenched martensite formed in the weld on the CLAM side, and the precipitates coarsened and aggregated in the outer HAZ, however, uniform austenite microstructures formed on the 316 L side of the weld. The microhardness profiles were asymmetric, and the maximum hardness zones located at the nugget on the CLAM side ranged from 350 to 450 HV. Softening in the outer HAZ on the CLAM side was observed, which was more pronounced in case 2. The welded joints had excellent tensile properties and always reached the tensile strength of the 316 L base metal. Better tensile properties of the welded joint were obtained in case 1, and the bonding strength of interfaces between CLAM and 316 L steels were always excellent in both cases.
- Published
- 2019
18. Effect of cube texture on local softening of stationary shoulder friction stir welding for thick-plate Al-Li alloy
- Author
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Chao Gu, Xinqi Yang, Wenshen Tang, Chaobo Tian, and Yongsheng Xu
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Mechanics of Materials ,Mechanical Engineering ,General Materials Science ,Condensed Matter Physics - Published
- 2022
19. Texture features and strengthening mechanisms in welding nugget zone of SSFSWed thick-plate Al–Li alloy joint
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Chao Gu, Xinqi Yang, Wenshen Tang, Yongsheng Xu, and Chaobo Tian
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Mechanics of Materials ,Mechanical Engineering ,General Materials Science ,Condensed Matter Physics - Published
- 2022
20. Revisiting the preparation of titanium dioxide: aerosol-assisted production of photocatalyst with higher catalytic activity than P25
- Author
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Jingjing Zhan, Xiujuan Zhang, Xinqi Yang, Yang Liu, Zhichen Si, Hongkun Chen, Chen Xiaofei, and Hao Zhou
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Materials science ,020502 materials ,Mechanical Engineering ,02 engineering and technology ,Catalysis ,chemistry.chemical_compound ,symbols.namesake ,Reaction rate constant ,0205 materials engineering ,chemistry ,X-ray photoelectron spectroscopy ,Chemical engineering ,Mechanics of Materials ,Titanium dioxide ,Methyl orange ,symbols ,Photocatalysis ,Particle ,General Materials Science ,Raman spectroscopy - Abstract
This research revisited the preparation of the pure titanium dioxide. Through the aerosol-assisted technology and our self-made setup, a kind of titanium dioxide with higher activity than commercial product P25 was successfully fabricated, while this aerosol-assisted process takes only about 10 s. By adjusting the operation temperature, the obtained titanium dioxide nanoparticles have different crystalline sizes and phase compositions, which are two major factors determining the catalytic activity of the materials. The results show that the optimum temperature was 600 °C, and the AST-600 particle prepared under this condition has the rate constant at 1.49 in the removal of methyl orange, which is 2.36 times that of Degussa P25. Although the AST-600 particle could only be activated by UV light similar to P25, the efficiency of AST-600/g-C3N4 is higher than that of P25/g-C3N4 under the visible condition. Meanwhile, the as-prepared titanium dioxide particles have been thoroughly characterized by TEM, SEM, XRD, PL, XPS, DRS, Raman and nitrogen adsorption in the study. Hence, we prepared a pure titanium dioxide with higher catalytic activity than P25, but the process is still very convenient, low cost and easy to scale up, holding great potential as an alternative to commercial product P25.
- Published
- 2019
21. Effects of supporting plate hole and welding force on weld formation and mechanical property of friction plug joints for AA2219-T87 friction stir welds
- Author
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Dongpo Wang, Kaixuan Liu, Xinqi Yang, Zhuanping Sun, and Bo Du
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Materials science ,Mechanical Engineering ,Metals and Alloys ,Welding ,Microstructure ,law.invention ,Mechanics of Materials ,Dimple ,law ,Solid mechanics ,Ultimate tensile strength ,Fracture (geology) ,Deformation (engineering) ,Composite material ,Joint (geology) - Abstract
Friction plug welding (FPW) experiments were performed on 8-mm-thick 2219-T87 FSW welds to investigate the weld formation, microstructure, hardness distribution, mechanical property, and fracture behaviors of FPW joint. The main findings are as follows: geometric size of supporting plate hole and welding force exert great effect on weld formation and mechanical property. Recrystallized zone (RZ) with varied width is observed on the bonding interface between the plug and base metal due to huge friction heat and deformation. Softening is found near the bonding interface due to the disappearance of cold working and transformation of constituent particles. The ultimate tensile strength (UTS) and elongation of FPW joint can reach 336.3MPa and 8%, respectively. The initial fracture of tensile specimen is prone to locate at the lower part of RZ. The tensile fracture morphology of FPW joint is characterized by dimples.
- Published
- 2019
22. Interfacial bonding features of friction stir additive manufactured build for 2195-T8 aluminum-lithium alloy
- Author
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Dongxiao Li, Shengli Li, Zijun Zhao, and Xinqi Yang
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0209 industrial biotechnology ,Materials science ,Strategy and Management ,Alloy ,Mixing (process engineering) ,chemistry.chemical_element ,Rotational speed ,02 engineering and technology ,Welding ,Conical surface ,Management Science and Operations Research ,engineering.material ,021001 nanoscience & nanotechnology ,Microstructure ,Industrial and Manufacturing Engineering ,law.invention ,020901 industrial engineering & automation ,chemistry ,Aluminium ,law ,Ultimate tensile strength ,engineering ,Composite material ,0210 nano-technology - Abstract
Friction stir additive manufacturing (FSAM) was performed successfully using 2 mm thick sheets of 2195-T8 aluminum-lithium alloy. The influence of the tool pin shape and process parameters on the interfacial bonding features among the additive manufactured layers was discussed, and the effects of interfacial defects on the performances of the additive build were analyzed based on microstructures, hardness profiles, and mechanical property evaluations. It is shown that the shape of the tool pin is one of the key factors in influencing the bonding interface between two manufactured layers. The cylindrical pin and the conical pin with three flats are not suitable for the FSAM process since very poor material mixing features are produced along the bonding interface. Although the material mixing degree of bonding interface is obviously improved at the advancing side (AS) interface of the nugget zone (NZ) by using the convex featured pin or the pin with three concave arc grooves, the material mixing degree at the retreating side (RS) interface of the NZ is always insufficient. Meanwhile, the weak-bonding defects along the bonding interfaces could be formed, which are originated from the hooking defects on the RS. The weak-bonding defects are related to the oxides and impurities existing at the original bonding interfaces as well as the insufficient stirring action of the tool pin. The back and forth double passes welding is one of the effective methods to improve the material mixing in the whole NZ and eliminate the hooking defects extending into the NZ. The welding rotation speeds of 800, 900 and 1000 rpm for giving welding speed of 100 mm/min were used in the additive manufacturing processes of 2195-T8 aluminum-lithium alloy, in which the optimum microstructure is obtained with the rotation speed of 800 rpm. The soften degree for the multilayered build is obvious, and the hardness profiles across the different bonding interfaces are always uneven. Meanwhile, compared with the AS interface, the fluctuation of the hardness value at the RS interface is greater. The mechanical properties of the multilayered build are inhomogeneous, and the maximum tensile strength of the multilayered build is only reached the 56.6% of the base metal. The mechanical properties are closely associated with the soften tendency of the material and the degree of the amelioration of weak-bonding defect along the bonding interface.
- Published
- 2019
23. Microstructural characteristics and mechanical properties of friction-stir-welded modified 9Cr–1Mo steel
- Author
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Shengli Li, Huijun Li, Wenshen Tang, Xinqi Yang, and Feixiang Wang
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Heat-affected zone ,Materials science ,Scanning electron microscope ,020502 materials ,Mechanical Engineering ,02 engineering and technology ,Welding ,Microstructure ,law.invention ,0205 materials engineering ,Mechanics of Materials ,law ,Martensite ,Ultimate tensile strength ,Friction stir welding ,General Materials Science ,Composite material ,Electron backscatter diffraction - Abstract
The modified 9Cr–1Mo steel was selected to conduct friction stir welding experiment. Defect-free welded joints were successfully obtained with the welding parameters of 300 rpm–50 mm/min and 400 rpm–50 mm/min. The microstructures of the welded joint were observed by scanning electron microscopy, electron backscatter diffraction and transmission electron microscope. The main microstructural characteristics of the weld zone (WZ) and the high-temperature heat affected zone are the formation of fresh quenched martensite, dissolution of M23C6 carbides, grain refinement and increase in kernel average misorientation. The WZ is significantly hardened, and the maximum hardness of this region is about twice that of the base material (BM). The ultimate tensile strength of the welded joint is up to 98% that of BM. The absorbed impact energies of the SZ and HAZ reach 77.8% and 87.4% that of the BM, respectively. Besides, the influence of post weld heat treatment on the microstructure and mechanical properties of the welded joint was also investigated.
- Published
- 2019
24. Effect of friction stir processing on microstructure and work hardening behavior of reduced activation ferritic/martensitic steel
- Author
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Feixiang Wang, Huijun Li, Shengli Li, Wenshen Tang, and Xinqi Yang
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0209 industrial biotechnology ,Materials science ,Friction stir processing ,Strategy and Management ,02 engineering and technology ,Work hardening ,Management Science and Operations Research ,Strain hardening exponent ,021001 nanoscience & nanotechnology ,Microstructure ,Industrial and Manufacturing Engineering ,020901 industrial engineering & automation ,Ultimate tensile strength ,Hardening (metallurgy) ,Composite material ,0210 nano-technology ,Tensile testing ,Electron backscatter diffraction - Abstract
The effects of friction stir processing (FSP) on microstructures, tensile properties and work hardening behavior of reduced activation ferritic/martensitic steel (RAFM) under different rotation speeds were investigated. The microstructures of FSP samples were examined by scanning electron microscopy (SEM), Electron back scatter diffraction (EBSD) and transmission electron microscope (TEM). Tensile test results show that the FSP samples not only have high strength, but also have good ductility simultaneously. The FSP samples of 150 rpm exhibit the best ductility with an elongation of about 1.5 times that of the base material (BM). The FSP samples of 200 rpm present a good match between strength and ductility, and the ultimate tensile strength (UTS) and total elongation are increased by 77.2% and 34.2%, respectively. FSP samples reveal lower hardening capacity and lower work hardening exponent than BM. As the rotation speed increases, the hardening capacity and the work hardening exponent of the FSP samples gradually decrease. Both BM and FSP samples can be divided into stage III and IV in the Kocks-Mecking type plot of work hardening rate. The FSP samples present the lower absolute slope value at stage III relative to BM. Besides, the FSP samples of 150 rpm and 250 rpm reveal the smallest and largest work hardening rate at stage IV, respectively.
- Published
- 2019
25. Effects of welding parameters on microstructure and mechanical properties of underwater wet friction taper plug welded pipeline steel
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Xinqi Yang, Junzhen Xiong, Kaixuan Liu, and Wei Lin
- Subjects
0209 industrial biotechnology ,Materials science ,Bainite ,Mechanical Engineering ,Metals and Alloys ,Rotational speed ,02 engineering and technology ,Welding ,Microstructure ,020501 mining & metallurgy ,law.invention ,020901 industrial engineering & automation ,0205 materials engineering ,Mechanics of Materials ,law ,Martensite ,Ferrite (magnet) ,Friction welding ,Composite material ,Base metal - Abstract
Microstructure and mechanical properties of underwater wet friction taper plug-welded API X52 pipeline steel with 6500–7500-rpm rotational speed at 30–45-kN axial force have been investigated, and the defect-free friction taper plug-welded joints were obtained. It was found that the microstructure in welded joint was remarkably inhomogeneous and very different from the X52 base metal. The weld region could be divided into forged zone (FZ), final frictional plane (FFP), shear deformation zone (SDZ), bonding zone (BZ), and heat-affected zone (HAZ). The HAZ has the coarsest grain and mainly consists of martensite and bainite, and the FZ and SDZ are mainly characterized by a mixture of martensite, bainite, and various shapes of ferrites. The BZ is represented by the banding pattern of fine equi-axed grain ferrites because of local decarbonization around frictional interface in wet welding condition. The axial force has a greater impact on microstructure of welded joint as compared with rotational speed. The hardness profiles measured on cross section of welded joints are severely non-uniform, ranging from 200 to 400 HV1, due to the inhomogeneity of microstructures. The impact absorbed energy of bonding interface sites in welds was considerably lower than that of base metal (about 20% of parent metal) because of the local obviously coarse grain, Widmanstatten ferrites, and banding ferrite defects. The principle of “close mode” friction welding is illustrated, and the microstructural characteristics and mechanical properties of welds can be predicted by judging the type of friction welding.
- Published
- 2018
26. Research on the Inter-zonal Heat Transfer Coefficient in Thermally Stratified Environment of Floor-Level Air-Supply System
- Author
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Xinqi Yang, Yuantao Xue, and Haidong Wang
- Subjects
Computer simulation ,business.industry ,Cooling load ,Airflow ,Heat transfer coefficient ,Mechanics ,Computational fluid dynamics ,Division (mathematics) ,law.invention ,law ,Ventilation (architecture) ,Thermal ,Environmental science ,business - Abstract
Stratum ventilation with air supply terminal located on the floor level near side-wall is typical for large space building, consequentially resulting in vertical thermal stratification. Heat accumulation in the upper part of unoccupied zone will have significant effect on the cooling load of occupied zone. In order to accurately predict the indoor thermal environment and load characteristics of large space building, and to calculate the heat migration occurring in the thermally stratified environment, the determination of inter-zonal heat transfer coefficient Cb is critical. This paper discusses the method to calculate inter-zonal heat transfer coefficient to represent a large space building. In a scaled laboratory, five experiment cases with different exhaust air flow ratios, heat source powers are studied. CFD simulations of the same cases are performed. The vertical temperature distribution and detailed cooling load results of the entire system and occupied zone are verified based on the experiment results. By dividing the whole space vertically into two and five zones, inter-zonal heat transfer coefficient Cb under different heat source heights is calculated from the CFD numerical simulation results. The results show that the area division method, airflow pattern, airflow state of occupied zone and the heat source affect Cb value.
- Published
- 2020
27. Evaluation of inhomogeneity in tensile strength and fracture toughness of underwater wet friction taper plug welded joints for low-alloy pipeline steels
- Author
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Wei Lin, Junzhen Xiong, Kaixuan Liu, and Xinqi Yang
- Subjects
0209 industrial biotechnology ,Toughness ,Materials science ,Fissure ,Strategy and Management ,02 engineering and technology ,Welding ,Management Science and Operations Research ,021001 nanoscience & nanotechnology ,Microstructure ,Industrial and Manufacturing Engineering ,law.invention ,020901 industrial engineering & automation ,Fracture toughness ,medicine.anatomical_structure ,law ,Ultimate tensile strength ,Fracture (geology) ,medicine ,Composite material ,0210 nano-technology ,Joint (geology) - Abstract
The microstructural characteristics of underwater wet friction taper plug welded joints for API X52 pipeline steel were investigated and tensile strength and facture toughness of the welded joints were experimentally evaluated. The microstructure of welded joints is considerably inhomogeneous. The tensile strength of welded joints shows heterogeneity in thickness direction. All of the tensile specimens taken from upper side of welded joints fracture at base material, while those taken from the bottom are broken at bonding interface or base material. The fracture toughness of welded joints deteriorates seriously, as compared with base material. The welded joints with notches in weld center have higher fracture toughness than those in bonding zone and the axial force has few influences on fracture toughness of welded joints. The bonding zone between plug and base plate should play a role as fissure defect for the whole welded joint, considering that it is tens of microns and much softer than its vicinity. In addition, the coarse grain, quenched martensite and Widmanstatten ferrite in weld region should also be responsible for the reduction of fracture toughness.
- Published
- 2018
28. Bioprecipitation facilitates the green synthesis of sulfidated nanoscale zero-valent iron particles for highly selective dechlorination of trichloroethene
- Author
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Xiujuan Zhang, Xinqi Yang, Hongkun Chen, Jingjing Zhan, Xiyun Cai, and Yuxin Wang
- Subjects
Zerovalent iron ,Environmental remediation ,Process Chemistry and Technology ,Nanoparticle ,Dithionite ,Pollution ,Sodium sulfide ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Bioprecipitation ,Chemical Engineering (miscellaneous) ,Degradation (geology) ,Reactivity (chemistry) ,Waste Management and Disposal - Abstract
Compared with nanoscale zero-valent iron particles (nZVI), sulfidated zero-valent iron nanoparticles (S-nZVI) exhibit higher reactivity and selectivity towards the remediation of halogenated organic pollutants such as trichloroethene (TCE). However, traditional methods of preparing S-nZVI are not safe and environmentally friendly to some degree. In this study, we developed a biological precipitation method to prepare S-nZVI, in which sulfate-reducing bacteria (SRB) played an important role for the in situ formation of ferrous disulfide on the surface of nZVI. The results show that the obtained sulfidated nZVI particles (BP-S-nZVI) exhibit excellent performance in TCE degradation, and the first-order rate coefficient (Kobs) and the efficiency of electron utilization were up to (1.66 ± 0.1)× 10-1 h-1 and 85%, respectively. Moreover, zero-valent iron utilization efficiency of BP-S-nZVI reached 95%. Meanwhile, the particles were well characterized and the mechanism for enhanced reactivity was explored. The prominent advantage of this novel method is that the harmful chemical sulfidating agents such as dithionite (S2O42−) and sodium sulfide (Na2S) are not required, making the preparation process more environmental-friendly, green and sustainable.
- Published
- 2021
29. Efficient and stable deep-blue narrow-spectrum electroluminescence based on hybridized local and charge-transfer (HLCT) state
- Author
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Shitong Zhang, Weijun Li, Haichao Liu, Ying Gao, Xinqi Yang, Shengbing Xiao, and Bing Yang
- Subjects
Brightness ,Materials science ,business.industry ,Process Chemistry and Technology ,General Chemical Engineering ,Charge (physics) ,02 engineering and technology ,State (functional analysis) ,Electroluminescence ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,OLED ,Optoelectronics ,Quantum efficiency ,0210 nano-technology ,business ,Common emitter ,Diode - Abstract
Two phenanthroimidazole-acridine derivatives (DPM and TDPM) were designed and synthesized for deep-blue organic light-emitting diode (OLED). Twisted combined rigid structures with hybridized local and charge-transfer (HLCT) state properties enable them to achieve excellent OLED performance. Non-doped OLEDs based on DPM and TDPM show decent deep-blue narrow-spectrum emission with Commission International de L’Eclairage (CIE) coordinates of (0.157, 0.053) and (0.158, 0.045), as well as maximum external quantum efficiency (EQEmax) of 4.0% and 2.6%, respectively. More importantly, OLEDs based on TDPM exhibit a smaller efficiency roll-off (12%) than that of DPM (35%) at high brightness (820 cd m−2 for DPM and 893 cd m−2 for TDPM, respectively). Overall, our work provides a molecular design strategy of HLCT materials for efficient deep-blue OLED with high color purity using purely organic emitter.
- Published
- 2021
30. The influence of post-weld tempering temperatures on microstructure and strength in the stir zone of friction stir welded reduced activation ferritic/martensitic steel
- Author
-
Napat Vajragupta, Huijun Li, Wenshen Tang, Shengli Li, Xinqi Yang, and Alexander Hartmaier
- Subjects
010302 applied physics ,Materials science ,Mechanical Engineering ,Metallurgy ,02 engineering and technology ,Welding ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Microstructure ,01 natural sciences ,law.invention ,Mechanics of Materials ,law ,Martensite ,0103 physical sciences ,Ultimate tensile strength ,Friction stir welding ,General Materials Science ,Tempering ,Dislocation ,0210 nano-technology ,Electron backscatter diffraction - Abstract
Reduced activation ferritic/martensitic (RAFM) steels are among the most competitive candidates of structural materials for nuclear fusion reactors, due to their superior comprehensive properties. Friction stir welding (FSW) was investigated in joining RAFM steel, considering its potential advantages in obtaining an optimal microstructure and mechanical properties of welded joint. To evaluate the feasibility of FSW in joining RAFM steel, an in-depth understanding of the microstructure-property relationships for friction stir welded joints of RAFM steel is necessary. In this research, the quantitative relationships between microstructural evolution and tensile properties in the stir zone (SZ) of friction stir welded RAFM steel after post-weld tempering treatment (PWTT) were systematically studied. Three different post-weld tempering temperatures namely 720 °C, 760 °C, and 800 °C were adopted. Then the uniaxial tensile properties were tested at room temperature and 550 °C, respectively. Electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), and the Thermo-Calc Calphad software were adopted to systematically investigate the microstructural evolution. Martensite lath width, precipitate number density, equilibrium solid solubility of alloying elements in the matrix, and geometrically necessary dislocation (GND) density were analyzed quantitatively. With the results obtained, we assessed the contribution of each strengthening mechanism to the 0.2% offset yield strength. According to the effective inter-barrier spacing theory, a microstructure-sensitive yield strength model was obtained to well predict the change in yield strength at different conditions. Finally, the results calculated by equivalent strengthening effect indicated that the crucial microstructure determining the yield strength of the SZ for RAFM steel after PWTT is the high density of dislocation substructures.
- Published
- 2021
31. Zigzag line defect in friction stir butt-weld of ferritic stainless steel
- Author
-
Huijun Li, Shengli Li, Wenshen Tang, and Xinqi Yang
- Subjects
Materials science ,Impact toughness ,Mechanical Engineering ,Butt welding ,Fracture mechanics ,02 engineering and technology ,Zigzag line ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,Mechanics of Materials ,Ultimate tensile strength ,General Materials Science ,Composite material ,0210 nano-technology ,Joint (geology) - Abstract
A zigzag line defect was detected in the stir zone (SZ) of friction stir butt-welded 12% Cr ferritic stainless steel joint. The characteristics and formation cause of the zigzag line defect was clarified and analyzed. The zigzag line defect presented the partly bonded feature but with relatively higher hardness, which did not affect the tensile properties at room temperature of the joint. The micro-void features of the zigzag line defect were considered to promote crack propagation under impact load, thereby significantly reducing the impact toughness of the SZ.
- Published
- 2021
32. Microstructural characteristics and mechanical heterogeneity of underwater wet friction taper plug welded joints for low-alloy pipeline steel
- Author
-
Kaixuan Liu, Xinqi Yang, Wei Lin, and Junzhen Xiong
- Subjects
Equiaxed crystals ,Materials science ,Bainite ,Mechanical Engineering ,Metallurgy ,02 engineering and technology ,Welding ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Microstructure ,020501 mining & metallurgy ,law.invention ,0205 materials engineering ,Mechanics of Materials ,law ,Martensite ,Ferrite (magnet) ,General Materials Science ,Friction welding ,Composite material ,0210 nano-technology ,Joint (geology) - Abstract
Underwater wet friction taper plug welding experiments have been performed on X52 pipeline steel with 6500–7500 rpm rotational speeds at 30–45 kN axial forces, and the microstructural characteristics and mechanical heterogeneity of defect-free friction taper plug welded joints are discussed thoroughly. It is found that the microstructure of welded joint is remarkably inhomogeneous and very different from the base metal. The welded joint has dramatically coarse grains and is dominantly characterized by a mixture of quenched martensite, upper bainite and various types of ferrites including Widmanstatten ferrite. Unlike the traditional solid-state friction welding processes, the relative homogeneous microstructure with fine and equiaxed grains cannot be obtained in the friction taper plug welding process. The axial force has a greater impact on microstructure of welded joint as compared to rotational speed. The hardness profiles measured in cross-section of welded joints are severely non-uniform, ranging from 200 to 400 HV1, due to the inhomogeneity of microstructure. The impact absorbed energy of welded joint with V-notch in the bonding zone was considerably lower than that of base material (about only 20% of parent metal) because of the local obviously coarse grain, Widmanstatten ferrite and banding ferrite defect. The microstructural inhomogeneity results in mechanical heterogeneity.
- Published
- 2017
33. Weakening mechanism and tensile fracture behavior of AA 2219-T87 friction plug welds
- Author
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Dongpo Wang, Bo Du, Xinqi Yang, Lei Cui, and Zhuanping Sun
- Subjects
0209 industrial biotechnology ,Heat-affected zone ,Materials science ,Mechanical Engineering ,Metallurgy ,02 engineering and technology ,Welding ,Condensed Matter Physics ,law.invention ,020303 mechanical engineering & transports ,020901 industrial engineering & automation ,0203 mechanical engineering ,Mechanics of Materials ,law ,Dimple ,Ultimate tensile strength ,Fracture (geology) ,Dynamic recrystallization ,General Materials Science ,Spark plug ,Joint (geology) - Abstract
In this paper, the weakening mechanism and tensile fracture behavior of AA 2219-T87 friction plug weld were investigated. The as welded friction plug joint involves six regions of plug metal (PM), plug thermo-mechanically affected zone (PTMAZ), recrystallized zone (RZ), thermo-mechanically affected zone (TMAZ), heat affected zone (HAZ), and base metal (BM). Owing to the severe material flow and plastic deformation at high welding temperatures, dynamic recrystallization would occur near the bonding interface. In TMAZ and HAZ, dissolution of θ′ phase, θ′ to θ transformation and coarsening of θ particles are observed. Throughout the weld, the minimum hardness value 87Hv is found in TMAZ near RZ. During tensile process, the initial strain concentration generates in TMAZ, and then intensifies and extends until eventual fracture of the joint. The fracture morphology of the joint is characterized by large and shallow dimples with second phases.
- Published
- 2017
34. Synthesis of star-branched PLA-b-PMPC copolymer micelles as long blood circulation vectors to enhance tumor-targeted delivery of hydrophobic drugs in vivo
- Author
-
Xubo Yuan, Ke Li, Jin Zhao, Li-mei Wang, Lixia Long, Jinjin Sun, Xiao-ming Qian, Xinqi Yang, Yu Ren, Li-gang He, Chunsheng Kang, and Chaoyong Liu
- Subjects
Materials science ,Atom-transfer radical-polymerization ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Micelle ,Ring-opening polymerization ,0104 chemical sciences ,chemistry.chemical_compound ,Polylactic acid ,chemistry ,Polymer chemistry ,Drug delivery ,Biophysics ,Click chemistry ,Copolymer ,General Materials Science ,Nanocarriers ,0210 nano-technology - Abstract
Star-branched amphiphilic copolymer nanocarriers with high-density zwitterionic shell show great promise in drug delivery due to their controllable small size and excellent anti-biofouling properties. This gives the hydrophobic cargo with high stability and long blood circulation in vivo . In the present study, star-branched polylactic acid and poly(2-methacryloyloxyethyl phosphorylcholine) copolymers with (AB 3 ) 3 –type architecture (PLA- b -PMPC 3 ) 3 were conceived as drug vectors, and the copolymers were synthesized by an “arm-first” approach via the combination of ring opening polymerization (ROP), atom transfer radical polymerization (ATRP) and the click reaction. The self-assembled star-branched copolymer micelles (sCPM) had an average diameter of about 64.5 nm and exhibited an ultra-hydrophilic surface with an ultralow water contact angle of about 12.7°, which efficiently suppressed the adhesion of serum proteins. In vivo experiments showed that the sCPM loading strongly enhanced the blood circulation time of DiI and the plasma half-life of DiI in sCPM was 19.3 h. The relative accumulation concentration in tumor of DiI delivered by sCPM was 2.37-fold higher than that of PLA-PEG, at 4 h after intravenous injection. These results demonstrated that the star-branched copolymer (PLA- b -PMPC 3 ) 3 is a promising alternative carrier material for intravenous delivery versus classic PEG-modified strategies.
- Published
- 2016
35. Thermal process influence on microstructure and mechanical behavior for friction taper plug welding in structural steel S355
- Author
-
Lei Cui, Feixiang Wang, Xinqi Yang, and Yayun Yin
- Subjects
0209 industrial biotechnology ,Materials science ,Bainite ,Mechanical Engineering ,Metallurgy ,Charpy impact test ,02 engineering and technology ,Welding ,Lath ,engineering.material ,021001 nanoscience & nanotechnology ,Microstructure ,Industrial and Manufacturing Engineering ,Acicular ferrite ,Computer Science Applications ,law.invention ,020901 industrial engineering & automation ,Control and Systems Engineering ,law ,Ferrite (iron) ,engineering ,Grain boundary ,0210 nano-technology ,Software - Abstract
The present work reports the influence of thermal process on microstructure and mechanical behavior for friction taper plug welding (FTPW) in structural steel S355. The results indicate that there is a significant decrease in total energy input and cooling time in temperature interval from 800 to 500 °C (Δt8/5) with increasing the axial force. However, the varying axial force has little effect on the peak temperature. The microstructure of weld zone contains acicular ferrite, polygonal ferrite, grain boundary allotriomorphic ferrite, and lath bainite. With decreasing total energy input and Δt8/5, the formation of lath bainite is promoted as well as the precipitation and growth of grain boundary allotriomorphic ferrite is inhibited. The hardness tends to increase with decreasing total energy input and Δt8/5. Charpy impact energy at the bonding line is almost 35 J ± 7 J for all specimens. On the other hand, Charpy impact energy at the weld zone increases gradually with decreasing total energy input and Δt8/5.
- Published
- 2016
36. Fabricating Defect-Free API X65 Steel Welds under Underwater Wet Conditions using Friction Taper Plug Welding
- Author
-
Feixiang Wang, Lei Cui, Xinqi Yang, and Yayun Yin
- Subjects
010302 applied physics ,Heat-affected zone ,Materials science ,Bainite ,Mechanical Engineering ,Metallurgy ,02 engineering and technology ,Welding ,Lath ,engineering.material ,021001 nanoscience & nanotechnology ,Microstructure ,01 natural sciences ,Industrial and Manufacturing Engineering ,Acicular ferrite ,law.invention ,Mechanics of Materials ,law ,Ferrite (iron) ,Martensite ,0103 physical sciences ,engineering ,General Materials Science ,Composite material ,0210 nano-technology - Abstract
The experiment on API X65 steel was carried out using friction taper plug welding (FTPW) under underwater wet conditions at room temperature. Sound weld formation can be achieved vastly at axial force ranging from 25 to 40 kN and a rotating speed of 7000 rpm. The microstructure of the weld zone consists of lath martensite, upper bainite, granular bainite, polygonal ferrite, and acicular ferrite. The microstructure of heat affected zone (HAZ) mainly consists of lath bainite as well as a bit of lath martensite and granular bainite. The tensile properties of defect-free welds are excellent. The maximum impact energy of the V-notch of bonding area can reach 110 J, which was conducted at 0°C with an error of ±12.5 J. The typical SEM impact fracture morphology presents areas of cleavage, quasi-cleavage, and dimples.
- Published
- 2016
37. Microstructure and mechanical properties of underwater friction taper plug weld on X65 steel with carbon and stainless steel plugs
- Author
-
W. Xu, J. Cao, Yayun Yin, Xinqi Yang, and Lei Cui
- Subjects
Austenite ,0209 industrial biotechnology ,Materials science ,Bainite ,Metallurgy ,02 engineering and technology ,Welding ,Lath ,engineering.material ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Microstructure ,law.invention ,020901 industrial engineering & automation ,law ,Residual stress ,Martensite ,engineering ,General Materials Science ,Composite material ,0210 nano-technology ,Spark plug - Abstract
Underwater friction taper plug welding for X65 pipeline steel was performed using Q345 structural steel and 316L stainless steel plugs. Weld microstructures, defects formation and mechanical properties were investigated. Using Q345 plugs can produce defect free and overmatching welded joints whose impact toughness was also favourable. Lower bainite and lath martensite in the weld zone resulted in high hardness with maximum value up to 418 HV10. Using 316L plugs can significantly reduce weld zone hardness due to austenite dominated microstructure. Microcracks can easily emerge at and may propagate along γ–δ phase boundaries to form macrocracks. Intermittent cracks were found along the bonding interface of all the 316L plug welds, which should be caused by the relief of the residual stress.
- Published
- 2016
38. Influence of weld geometry and process parameters on the quality of underwater wet friction taper plug welding
- Author
-
Shengli Li, Lei Cui, Yayun Yin, and Xinqi Yang
- Subjects
0209 industrial biotechnology ,Heat-affected zone ,Materials science ,Mechanical Engineering ,Metallurgy ,Charpy impact test ,Laser beam welding ,02 engineering and technology ,Welding ,021001 nanoscience & nanotechnology ,Electric resistance welding ,Industrial and Manufacturing Engineering ,Computer Science Applications ,law.invention ,020901 industrial engineering & automation ,Control and Systems Engineering ,law ,Ultimate tensile strength ,Cold welding ,Composite material ,0210 nano-technology ,Joint (geology) ,Software - Abstract
In the present study, a number of joints were fabricated successfully on DH36 marine steel sheet in underwater wet based on friction taper plug welding (FTPW). The influences of the plug and hole geometry parameters combination on the quality of welded joint forming were first investigated. It was found that tapered holes and plugs were the preferred choice and a suitable cone angle range was obtained. Using the preferred hole and plug designed further expand the range of welding parameters to explore process parameters influence on the welding quality. Bonding mechanism and microstructural evolution to FTP welds were investigated with multiple observations. Mechanical properties of the obtained joints were also evaluated with tensile and Charpy impact tests by reference to AWS D3.6 Underwater Welding Code. The best result is found as the joint welded with 7500 rpm and 40 kN which has 535.6 MPa ultimate tensile strength, 22.5 % elongation, and 42.5 J impact energy at bonding line.
- Published
- 2016
39. Characteristics of friction plug welding to 10 mm thick AA2219-T87 sheet: Weld formation, microstructure and mechanical property
- Author
-
Xinqi Yang, Jianling Song, Bo Du, Zhongping Zhang, Zhuanping Sun, and Lei Cui
- Subjects
0209 industrial biotechnology ,Heat-affected zone ,Materials science ,Mechanical Engineering ,Alloy ,Metallurgy ,02 engineering and technology ,Welding ,engineering.material ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Microstructure ,Material flow ,law.invention ,020901 industrial engineering & automation ,Mechanics of Materials ,Dimple ,law ,Ultimate tensile strength ,engineering ,General Materials Science ,0210 nano-technology ,Spark plug - Abstract
In this paper, friction plug welding (FPW) experiments of 2219-T87 aluminum alloy sheets with 10 mm thickness were performed. The material flow behavior, microstructures, second phases, mechanical properties and failure behaviors were also investigated. The results indicate that a sufficient volume of material from both plug and base metal flow upward and downward is critical obtaining defect free weld. The plug thermo-mechanically affected zone, plug recrystallized zone, thermo-mechanically affected zone (TMAZ), and heat affected zone could be weakened significantly owing to the thermal–mechanical process. The main reason is believed as the dissolution of precipitates and the redistribution of constituent particles. The maximum tensile strength and elongation of the joint would reach 329 MPa and 7%, respectively. The TMAZ closest to the bonding interface is the weakest location of the joints. The tensile crack initiates at TMAZ close to the bonding interface near the lower surface and then propagates along the soften area in TMAZ with forming a large amount of dimples with second phases existing at the bottom.
- Published
- 2016
40. The local strength and toughness for stationary shoulder friction stir weld on AA6061-T6 alloy
- Author
-
Xinqi Yang, Zhuanping Sun, Dongxiao Li, and Lei Cui
- Subjects
0209 industrial biotechnology ,Toughness ,Materials science ,Mechanical Engineering ,Metallurgy ,Alloy ,02 engineering and technology ,Welding ,engineering.material ,Plasticity ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Microstructure ,law.invention ,020901 industrial engineering & automation ,Mechanics of Materials ,law ,Ultimate tensile strength ,engineering ,Particle ,General Materials Science ,Composite material ,0210 nano-technology ,Base metal - Abstract
In this study, the local microstructure, strength and toughness of different zones in AA6061-T6 stationary shoulder friction stir welds were investigated. Results indicated that, the most significant weakening for both strength and toughness is found in HAZ that close to NZ. The microstructure of NZ includes recrystallized fine grains with high density of dislocations, homogeneous constituent particles distribution and re-precipitated of G.P. zones resulting in the recovery of local strength and the improvement for both plasticity and toughness. In HAZ, the grain structure and constituent particle distribution inherit the characteristics of base metal, but β″ precipitates are dissolved and the reprecipitated β′ particles are coarsened. This results in the decrease of yield strength, tensile strength, crack initial energy and propagation energy of HAZ, especially near NZ.
- Published
- 2016
41. Material flow influence on the weld formation and mechanical performance in underwater friction taper plug welds for pipeline steel
- Author
-
Xinqi Yang, Lei Cui, Yayun Yin, Shengli Li, and Feixiang Wang
- Subjects
Heat-affected zone ,Weld access hole ,Materials science ,Mechanical Engineering ,Metallurgy ,Welding ,Microstructure ,Electric resistance welding ,Material flow ,law.invention ,Mechanics of Materials ,law ,Ultimate tensile strength ,lcsh:TA401-492 ,lcsh:Materials of engineering and construction. Mechanics of materials ,General Materials Science ,Friction welding ,Composite material - Abstract
Friction taper plug welding experiment was conducted on X65 pipeline steel in underwater wet condition. Results indicate that the weld defects, microstructural evolution and mechanical properties are closely related to the material flow behavior during welding. The formation of weld defect characterized by incomplete filling or lack of bonding is mainly caused by the poor flowing property of the plug material especially in low axial welding force. In the experiment condition, rising the axial force would result in better material flow, higher weld power, more energy input and further improve the bond quality of the weld. Microstructure of both weld zone and heat-affected-zone mainly consists of lath bainite which results in an overmatching condition through the weld. High quality welds in this study also exhibit good tensile and impact properties that is equal to the base metal and acceptable bend property of 105° as the best. Keywords: Underwater welding, Friction taper plug welding, Material flow, Mechanical properties, Pipeline steel
- Published
- 2015
42. Deep blue electro-fluorescence and highly efficient chemical warfare agent sensor: Functional versatility of weak coupling hybridized locally excited and charge-transfer excited state
- Author
-
Bing Yang, Man Wang, Zhiyong Cheng, Shitong Zhang, Ying Gao, Xiangyu Meng, Hongwei Ma, Haichao Liu, and Xinqi Yang
- Subjects
Detection limit ,Coupling ,Chemical Warfare Agents ,Materials science ,business.industry ,Process Chemistry and Technology ,General Chemical Engineering ,Exciton ,Charge (physics) ,02 engineering and technology ,Electroluminescence ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Fluorescence ,0104 chemical sciences ,Excited state ,Optoelectronics ,0210 nano-technology ,business - Abstract
A weakly-coupled hybridized locally-excited and charge-transfer hybridized locally-excited and charge-transfer (HLCT) dual-functional material TPA-2CNTAZ is designed and synthesized. The dispersed state of TPA-2CNTAZ exhibits deep blue electroluminescent (EL) with an exceeding exciton utilization of 53%, and the aggregated state of TPA-2CNTAZ displays efficient detection to the analogue of chemical warfare agents with an excellent limit of detection of 0.69 ppb.
- Published
- 2020
43. Numerical analyses of material flows and thermal processes during friction plug welding for AA2219 aluminum alloy
- Author
-
Bo Du, Wenshen Tang, Xinqi Yang, and Zhuanping Sun
- Subjects
0209 industrial biotechnology ,Normal force ,Materials science ,Effective stress ,Metals and Alloys ,Rotational speed ,02 engineering and technology ,Welding ,Microstructure ,Industrial and Manufacturing Engineering ,Computer Science Applications ,law.invention ,Material flow ,020303 mechanical engineering & transports ,020901 industrial engineering & automation ,0203 mechanical engineering ,law ,Modeling and Simulation ,Ceramics and Composites ,Deformation (engineering) ,Composite material ,Spark plug - Abstract
A coupled thermo-mechanical model is developed for friction plug welding (FPW) process of AA2219 aluminum alloy, which is validated by the experimental results of the torque and temperature history. Both the deformation of plug and base metal are considered in this model. It is concluded that weak-bonding and unbonding is caused by the poor interface normal force and material flow based on the simulational and experimental results. Significant inhomogeneity in distribution of temperature, effective strain and effective stress is observed along the thickness direction of FPW joint, resulting in the inhomogeneity of microstructure and mechanical property. The peak temperature of bonding interface can reach 508 °C, which is 79% of the melting point of base metal. Higher welding force and rotational speed could promote material flow and improve interface normal force, which is beneficial to obtaining better connection.
- Published
- 2020
44. Investigation of stationary shoulder friction stir welding of aluminum alloy 7075-T651
- Author
-
Xinqi Yang, Dongxiao Li, Xu Zhang, Lei Cui, and Fangzhou He
- Subjects
Heat-affected zone ,Materials science ,Metallurgy ,Alloy ,technology, industry, and agriculture ,Metals and Alloys ,chemistry.chemical_element ,Welding ,engineering.material ,Industrial and Manufacturing Engineering ,Computer Science Applications ,law.invention ,chemistry ,Aluminium ,law ,Modeling and Simulation ,Ultimate tensile strength ,Ceramics and Composites ,engineering ,Friction stir welding ,Redistribution (chemistry) ,Dissolution - Abstract
Stationary shoulder friction stir welding (SSFSW) was successfully performed on 7075-T651 aluminum alloy. Defect-free joints with smooth weld surface were obtained. The redistribution of constituent particles and the dissolution of η′ precipitates resulted in the low crack initiation energy of the nugget zone. The low crack initiation energy in the heat affected zone (HAZ) can be attributed to both the presence of η precipitates and the redistribution of constituent particles. The presence of η precipitates in the HAZ was the major reason for the decreased tensile strength of SSFSW joint.
- Published
- 2015
45. Fatigue property of stationary shoulder friction stir welded additive and non-additive T joints
- Author
-
Xinqi Yang, Xiang Zhang, Dongxiao Li, Fangzhou He, and Lei Cui
- Subjects
musculoskeletal diseases ,Materials science ,Metallurgy ,technology, industry, and agriculture ,Fatigue testing ,Welding ,Condensed Matter Physics ,Microstructure ,law.invention ,law ,Fracture (geology) ,Bending fatigue test ,Friction stir welding ,General Materials Science ,Composite material ,Joint (geology) ,Stress concentration - Abstract
Additive and non-additive T joints were successfully fabricated by stationary shoulder friction stir welding using various welding parameters. No interior defects were observed in all joints by microstructural examination. The fatigue property of both additive and non-additive joints was revealed by four-point bending fatigue test. The microstructure and the stress concentration were investigated at the fatigue crack initiation sites of various T joints. Stress concentration determines the fracture location, and the surface microstructure influences the fatigue property. The stress concentration at the internal corner was evidently lower for additive joint than non-additive joint. The surface of stationary shoulder friction welded joint was characterised by ultrafine grains, which evidently enhanced the fatigue property.
- Published
- 2015
46. Investigation on welding parameters and bonding characteristics of underwater wet friction taper plug welding for pipeline steel
- Author
-
Jun Cao, Wei Xu, Lei Cui, Yayun Yin, and Xinqi Yang
- Subjects
Heat-affected zone ,Materials science ,Bainite ,Mechanical Engineering ,Metallurgy ,Laser beam welding ,Welding ,Electric resistance welding ,Microstructure ,Industrial and Manufacturing Engineering ,Computer Science Applications ,law.invention ,Control and Systems Engineering ,law ,Friction welding ,Composite material ,Spark plug ,Software - Abstract
The Q235 and X65 steel tapered plugs were used to perform friction taper plug welding (FTPW) on X65 pipeline steel in underwater wet condition. The work concentrates on defect formation, torque variation, energy input during FTPW, and also the weld microstructures and hardness. Energy input is proportional to torque-time integration under constant rotating speed and is critical to realize metallurgical bonding between the hole and plug. Increasing burn-off can prolong welding time, thus enhancing energy input, so that defect can be eliminated. Using X65 plug can produce defect-free welds since the energy input is adequate. However, when Q235 plug is used, lack of bonding is commonly found as a kind of root defect in friction taper plug (FTP) weld owing to the insufficient energy input. The weld zone microstructure mainly consists of upper bainite in X65 plug weld, but Widmanstatten structure in Q235 weld. In heat-affected zone, the microstructure is found as upper bainite in both X65 and Q235 plug welds.
- Published
- 2015
47. Effect of welding parameters on microstructure and mechanical properties of AA6061-T6 butt welded joints by stationary shoulder friction stir welding
- Author
-
Lei Cui, Xinqi Yang, Hao Shen, Fangzhou He, and Dongxiao Li
- Subjects
Heat-affected zone ,Transverse plane ,Materials science ,law ,Ultimate tensile strength ,Metallurgy ,Friction stir welding ,Welding ,Rotation ,Microstructure ,Joint (geology) ,law.invention - Abstract
Stationary shoulder friction stir welding (SSFSW) butt welded joints were fabricated successfully for AA6061-T6 sheets with 5.0 mm thickness. The welding experiments were performed using 750–1500 rpm tool rotation speeds and 100–300 mm/min welding speeds. The effects of welding parameters on microstructure and mechanical properties for the obtained welds were discussed and analyzed in detail. It is verified that the defect-free SSFSW welds with fine and smooth surface were obtained for all the selected welding parameters, and the weld transverse sections are obviously different from that of conventional FSW joint. The SSFSW nugget zone (NZ) has “bowl-like” shapes with fairly narrow thermal mechanically affected zone (TMAZ) and heat affected zone (HAZ) and the microstructures of weld region are rather symmetrical and homogeneous. The 750–1500 rpm rotation speeds apparently increase the widths of NZ, TMAZ and HAZ, while the influences of 100–300 mm/min welding speeds on their widths are weak. The softening regions with the average hardness equivalent 60% of the base metal are produced on both advancing side and retreating side. The tensile properties of AA6061-T6 SSFSW joints are almost unaffected by the 750–1500 rpm rotation speeds for given 100 mm/min, while the changing of welding speed from 100–300 mm/min for given 1500 rpm obviously increased the tensile strength of the joint and the maximum value for welding parameter 1500 rpm and 300 mm/min reached 77.3% of the base metal strength. The tensile fracture sites always locate in HAZ either on the advancing side or retreating side of the joints.
- Published
- 2014
48. Influence of processing parameters on microstructure and mechanical performance of refill friction stir spot welded 7075-T6 aluminium alloy
- Author
-
J. S. C. Hou, Xinqi Yang, Y. Chen, Adrian P. Gerlich, and Zhikang Shen
- Subjects
Heat-affected zone ,Materials science ,Scanning electron microscope ,Metallurgy ,Welding ,Condensed Matter Physics ,Microstructure ,law.invention ,Optical microscope ,law ,visual_art ,Aluminium alloy ,visual_art.visual_art_medium ,Shear strength ,General Materials Science ,Spot welding - Abstract
Refill friction stir spot welding (FSSW) is a solid state joining technology recently derived from conventional FSSW. In the present study, refill FSSW was performed in a 0·8 mm thick AA7075-T6 aluminium alloy with varying welding parameters (welding time and plunge depth). The influence of welding parameters on the microstructure and mechanical properties of the weld was investigated in terms of nugget thickness, hardness and overlap shear strength. The microstructural features and fracture mechanism were observed by optical microscopy and scanning electron microscopy. The results indicate that the nugget thickness increases with increasing welding time and plunge depth. Furthermore, melted films observed in the stir zone (SZ) were consistent with a maximum temperature of 470·9°C measured 2·6 mm away from the SZ. The overlap shear strength increases with the increase of weld time and plunge depth due to increasing nugget diameter.
- Published
- 2014
49. Experimental study of friction taper plug welding for low alloy structure steel: Welding process, defects, microstructures and mechanical properties
- Author
-
Wei Xu, Dongpo Wang, Jun Cao, Xinqi Yang, and Lei Cui
- Subjects
Heat-affected zone ,Filler metal ,Materials science ,law ,Metallurgy ,Laser beam welding ,Cold welding ,Friction welding ,Welding ,Electric resistance welding ,Upset welding ,law.invention - Abstract
A research investigation has been undertaken to identify the various stages and variation of welding parameters in friction taper plug welding (FTPW) process and to explore their effects on the performance and properties of the welds. According to the variation of axial force, the overall FTPW process is divided into feeding phase, pressing phase, welding phase, and forging phase. The rotating speed, welding force, and burn-off rate remain nearly constant in welding phase. However, the torque peaks in welding phase when after few seconds of welding force setting is reached. Rising the welding force would increase the peak torque, welding torque, and burn-off rate, but decrease the welding time. When improper welding parameter is used lack of bonding and incomplete filling defects would form within the weld. The microstructure of the weld metal is consist of retained austenite, pearlite, and various Widmanstatten ferrite. In heat affect zone, it is mainly of lathy upper bainite. Defect free welds exhibit favorable tensile properties of which 548.3 MPa tensile strength and 27.5% elongation that equal to the base metal could be found.
- Published
- 2014
50. Analysis and Comparison of Long-Distance Pipeline Failures
- Author
-
Xinqi Yang, Ting Wang, Dongpo Wang, Qingshan Feng, and Lianshuang Dai
- Subjects
Operations research ,Risk analysis (engineering) ,Article Subject ,Computer science ,business.industry ,Risk analysis (business) ,Pipeline (computing) ,Fossil fuel ,Integrity assessment ,business - Abstract
The analysis results of long-distance oil and gas pipeline failures are important for the industry and can be the basis of risk analysis, integrity assessment, and management improvement for pipeline operators. Through analysis and comparison of the statistical results of the United States, Europe, the UK, and PetroChina in pipeline failure frequencies, causes, consequences, similarities, and differences of pipeline management, focusing points and management effectiveness are given. Suggestions on long-distance pipeline safety technology and management in China are proposed.
- Published
- 2017
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