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Effect of Isothermal Forging on the Microstructure and Mechanical Properties of Mg-8Gd-3Y-0.5Zr Alloy

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上海航天（中英文） 2022年第1期39卷 186-195,204页

作者： HOU Xiangwu WANG Yanbo ZHOU Haitao SUN Xin GONG Zhengxuan JIANG Shanyao XIAO Lü Shanghai Spaceflight Precision Machinery Institute Shanghai 201600China

Aiming at the problems of poor plastic forming ability,narrow forging temperature range,and strain rate sensitivity of rare earth magnesium alloys,a study on the microstructure and mechanical properties of Mg-8Gd-3Y-0.5Zr alloy with different isothermal forging processes is carried out.The microstructure and properties of the alloy in the as-cast,isothermal forged,and post-aging states after forging are studied with optical microscope(OM),scanning electron microscope(SEM),and tensile testing.The results show that significant dynamic recrystallization occurs during the isothermal forging process,a fine equiaxed grain structure is formed,and the mechanical properties of the alloy are greatly improved.When the isothermal forging temperature is 460℃ and the strain rate is 0.02 s^(-1),the alloy structure performance is the best,the room temperature tensile yield strength(TYS)is 218 MPa,the ultimate tensile strength(UTS)is 299 MPa,and the fracture elongation(FE)is 19.2%.When the alloy is post-forging artificial aged,theα-Mg matrix is dispersed,the Mg_5(Gd,Y)phase is precipitated,the UTS of the alloy is increased to 392 MPa,and the FE is reduced to 12.0%.

关键词： Mg-8Gd-3Y-0.5Zr alloy isothermal forging microstructure mechanical property

Supervised descent method for weld pool boundary extraction during fiber laser welding process

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China Welding 2019年第1期28卷 6-10页

作者：赵耀邦张登明吴远峰杨长祺 Shanghai Spaceflight Precision Machinery Institute

In order to obtain a high-quality weld during the laser welding process, extracting the characteristic parameters of weld pool is an important issue for automated welding. In this paper, the type 304 austenitic stainless steel is welded by a 5 kW high-power fiber laser and a high-speed camera is employed to capture the topside images of weld pools. Then we propose a robust visual-detection approach for the molten pool based on the supervised descent method. It provides an elegant framework for representing the outline of a weld pool and is especially efficient for weld pool detection in the presence of strong uncertainties and disturbances. Finally, welding experimental results verified that the proposed approach can extract the weld pool boundary accurately, which will lay a solid foundation for controlling the weld quality of fiber laser welding process.

关键词： fiber laser welding molten pool supervised descent method boundary extraction

基于Simulink和Comsol联合仿真的虚拟热测试系统

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Aerospace China 2022年第3期23卷 38-43页

作者： ZHOU Xingguang LIU Bo JIANG Gang WANG Zhaoxi LIANG Di LIU Shiling Shanghai Spaceflight Precision Machinery Institute Shanghai 201600

A virtual thermal test system was built through the co-simulation using Simulink and Comsol to realize the complete virtualization of the thermal test.Using the co-simulation technology,comprehensive simulation analysis of the control system,electric field and thermal field was realized.The data state of each observation point could be directly observed at one time,including the output state information of the power amplifier,the output state information of the heater,and the thermal state information of the test unit.The virtual thermal test system has a predictive and guiding role for engineering thermal tests,and can realize thermal environment simulation beyond the existing thermal environment ground simulation capabilities,providing a basis for the development of future models.

关键词： Simulink Comsol co-simulation virtual thermal test system

Learning semantic-specific visual representation for laser welding penetration status recognition

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Science China(Technological Sciences) 2022年第2期65卷 347-360页

作者： LIU TianYuan BAO JinSong ZHENG HangBin WANG JunLiang YANG ChangQi GU Jun institute of Intelligent Manufacturing College of Mechanical EngineeringDonghua UniversityShanghai 201600China Shanghai Spaceflight Precision Machinery Institute Shanghai 201600China shanghai institute of Laser Technology Shanghai 200235China

The degree of penetration can directly reflect the forming quality of laser welding. The fine-grained feature of the molten pool/keyhole image brings challenges to the vision-based laser welding penetration status recognition. In this paper, a novel knowledge-and-data-hybrid driven recognition model is proposed for solving the problem of difficult learning of discriminative visual features of molten pool/keyhole images. In addition, a label semantic attention mechanism(LSA) is designed with three modules: representation of image visual feature, representation of labels semantic feature, and generation of label semantic attention. For learning discriminative features in visual space, LSA uses discriminative information in label semantics to guide the convolutional neural network. The experimental results show that the proposed LSA method has faster convergence and higher accuracy than the traditional attention mechanism. Further comparative experiments reveal that LSA is less dependent on the amount of training data and model complexity. The results of visualization experiments show that the visual features learned by the proposed method are more discriminative.

关键词： label semantic attention mechanism word embedding convolutional neural network laser welding penetration status

Investigations on the tensile deformation of pure Mg and Mg–15Gd alloy by in-situ X-ray synchrotron radiation and visco-plastic self-consistent modeling

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Journal of Magnesium and Alloys 2023年第2期11卷 607-613页

作者： Yuling Xu Yuanding Huang Yuye Wang Weiming Gan Shiwei Wang Emad Maawad Norbert Schell Norbert Hort Chongqing Academy of Science and Technology Chongqing 401123China institute of Materials Research Helmholtz-Zentrum GeesthachtGeesthacht 21502Germany Shanghai Spaceflight Precision Machinery Institute Shanghai 201600China

In this study,the texture evolutions of two Mg materials during tension are explored.In-situ X-ray synchrotron and Visco-Plastic SelfConsistent(VPSC) modeling are employed to investigate the different deformation modes between pure Mg and Mg-15Gd(wt.%) alloy.These two materials with a strong extrusion texture show large different slip/twinning activity behaviors during tensile deformation.The basal(a) slip has the highest contribution to the initial stage of plastic deformation for pure Mg.During the subsequent plastic deformation,the prismatic slip is dominant due to the strong ED//(100) fiber texture.In contrast,the deformation behavior of Mg-15Gd alloy is more complex.Twinning and basal slip are dominant at the early stage of plastic deformation,but further deformation results in the increased activation of prismatic and pyramidal slips.In comparison to pure Mg,the ratios of the critical resolved shear stress(CRSS) between non-basal slip and basal slip of the Mg-15Gd alloy are much lower.

关键词： Mg alloy Texture Mechanical behavior In-situ investigation

Study on the Deformation Behavior of Mg-Gd-Y-Zn-Mn Wrought Magnesium Alloys by Visco-plastic Self-consistent Modeling

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上海航天（中英文） 2022年第1期39卷 77-83,136页

作者： WANG Yuye ZHANG Junfa WANG Shiwei KANG Jing MENG Jiajie WANG Yanbo XU Yuling ZHOU Haitao Shanghai Spaceflight Precision Machinery Institute Shanghai 201600China Beijing institute of Space Long March Vehicle Beijing 100076China

The plastic deformation behavior of new Mg-Gd-Y-Zn-Mn magnesium alloys gains great necessity to clarify and understand the mechanism deeply. In the present work,the tensile mechanical property test and visco-plastic self-consistent (VPSC) model are used to investigate the activities of deformation modes of VW84M and VW94M magnesium alloys during the tensile deformation. The results show that the mechanical properties of the above extruded alloys are similar but VW94M has higher strength than VW84M after the same aging process. Compared with the extruded alloys,the as-aged alloys have significantly higher activation of pyramidal slip at the later stage of plastic deformation. In addition,the as-aged VW94M alloy with higher strength has the largest activity of pyramidal slip. In summary,the addition of Gd increases the critical resolved shear stress (CRSS)in each slip system of VW94M,while the increase in the strength and the decrease in the elongation of as-aged alloys are associated with the significant activation of pyramidal slip.

关键词： Mg-RE alloy wrought magnesium alloy visco-plastic self-consistent(VPSC)model deformation behavior

Knowledge Graph Construction and Rule Matching Approach for Aerospace Product Manufacturability Assessment

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Journal of Harbin institute of Technology(New series) 2024年

作者： Ziyan Liu Zujie Zheng Lebao Wu Zuhua Jiang School of Mechanical Engineering shanghai Jiao Tong University Shanghai Spaceflight Precision Machinery Institute

As representatives of high-precision parts， aerospace products are characterized by complex structures， long production cycles and high precision requirements. After the design of aerospace products is completed， a manufacturability assessment needs to be conducted based on 3D model features in terms of modeling quality and process design， otherwise the cost of design changes will be increased. Due to the poor structure and reusability of product manufacturing feature information and assessment knowledge in the current aerospace product manufacturability assessment process， it is difficult to realize automated manufacturability assessment. To address these issues， this paper first establishes a domain ontology model for aerospace product manufacturability assessment. On this basis， a structured representation method of manufacturability assessment knowledge and a knowledge graph data layer construction method are proposed. Based on the semantic information and association information expressed by the knowledge graph， a rule matching method based on subgraph matching is proposed to improve the precision and recall. Finally， applications and experiments based on the software platform verify the effectiveness of the proposed knowledge graph construction and rule matching method.

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Development and Application of Ti-based Alloy Casting Technologies in the Field of Aerospace

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上海航天（中英文） 2022年第1期39卷 1-14页

作者： HOU Zhengquan LI Baohui FENG Gangwen WU Jingxi FAN Lipeng GUO Yingfei CHEN Yuyong CHEN Bin ZHANG Xuliang Shanghai Spaceflight Precision Machinery Institute Shanghai 201600China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001HeilongjiangChina

Ti-based alloys have been widely applied in the aerospace field,owing to their outstanding performance.precision casting can be used to make integrated near-net-shape components with complex thin-walled structures,which will further promote the engineering application of Ti-based alloys. In this paper,the research progress of Tibased alloys,e. g.,high-temperature Ti-based alloys,high-strength Ti-based alloys,TiAl-based alloys,Ti-based matrix composites,and their precision casting technologies are reviewed. In addition,the development directions of Tibased alloys are presented based on the application status of Ti-based alloys in the aerospace field.

关键词： high-performance Ti-based alloy TiAl-based alloy Ti-based matrix composite precision casting aerospace

Fabrication and Investigation on Double-Hollow Shell CoFe Oxide@TiO_(2) Nanocube with Superior Electromagnetic Properties

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上海航天（中英文） 2022年第1期39卷 176-185页

作者： NI Xinyao TANG Chuanhao HUA Jiasong CHEN Yi ZHUANG Qixin School of Materials Science and Engineering East China University of Science and TechnologyShanghai 200237China Shanghai Spaceflight Precision Machinery Institute Shanghai 201600China

Electromagnetic wave absorbing materials are urgently required in the fields of medicine,communication,and military.However,the thickness,weight,narrow effective bandwidth,and weak absorbing ability of the materials restrict their further application.In this work,a double-layer hollow nanocube with a dielectric titanium dioxide(TiO_(2))shell and a magnetic CoFe oxide inner shell is prepared.Prussian blue(PB)is prepared by the hydrothermal method,and used as the template to prepare PB@CoFe PB analogue(PBA).After selective etching and further calcination,hollow CoFe oxide particles are obtained.The obtained particles are then coated with SiO_(2)and TiO_(2),respectively,and the intermediate layer is dislodged to obtain the final CoFe oxide@TiO_(2)with the hollow double shell structure.The obtained double-layer hollow structure can effectively capture the incident electromagnetic waves,and increase the propagation path.Moreover,the obvious enhancement of interface polarization and the improvement of impedance matching enhance the wave absorbing ability of the material.The analysis results show that,the structure is stable and the dispersion is good.The maximum reflection loss(RL)at 10 GHz is as high as-46.1 dB with the sample thickness of 1.6 mm.The light-weight and high-efficiency CoFe oxide@TiO_(2)absorber is promised to be used in commercial and military aerospace fields.

关键词： microwave absorption CoFe oxide titanium dioxide(TiO_(2)) dual-shelled dual-cavitys tructure nanocube