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In situ monitoring methods for selective laser melting additive manufacturing process based on images-A review

China Foundry 2021年第4期18卷 265-285页

作者： Bo Wu Xiao-yuan Ji Jian-xin Zhou Huan-qing Yang Dong-jian Peng Ze-ming Wang Yuan-jie Wu Ya-jun Yin State Key Laboratory of Materials Processing and Die&Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China Xi'an Space Engine Co. Ltd.Xi'an 710100China Center of National Defense Technology Industry Aerospace Special Components Additive Manufacturing Innovation Xi'an 710100China 4 Nuclear Power Institute of China Chengdu 610213China

Selective laser melting(SLM)has been widely used in the fields of aviation,aerospace and die manufacturing due to its ability to produce metal components with arbitrarily complex ***,the instability of SLM process often leads to quality fluctuation of the formed component,which hinders the further development and application of *** situ quality control during SLM process is an effective solution to the quality fluctuation of formed ***,the basic premise of feedback control during SLM process is the rapid and accurate diagnosis of the ***,an in situ monitoring method of SLM process,which provides quality diagnosis information for feedback control,became one of the research hotspots in this field in recent *** this paper,the research progress of in situ monitoring during SLM process based on images is ***,the significance of in situ monitoring during SLM process is ***,the image information source of SLM process,the image acquisition systems for different detection objects(the molten pool region,the scanned layer and the powder spread layer)and the methods of the image information analysis,detection and recognition are reviewed and *** review and analysis,it is found that the existing image analysis and detection methods during SLM process are mainly based on traditional image processing methods combined with traditional machine learning ***,the main development direction of in situ monitoring during SLM process is proposed by combining with the frontier technology of image-based computer vision.

关键词： selective laser melting(SLM) forming process images in situ monitoring molten pool region monitoring scanned layer and powder layer monitoring

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Trip Effect Detection of Medium Manganese Steel Based on the Mbn Signal

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SSRN 2023年

作者： Zhu, Bin Mei, Yongqi Pei, Junsen Wang, Zijian Zhang, Yisheng State Key Lab of Materials Processing and Die and Mould Technology Huazhong University of Science and Technology Hubei Wuhan430074 China School of Iron and Steel Soochow University Suzhou215006 China

For the enhanced strength and ductility requirement, medium manganese steel is viewed as a new material to improve the crashworthiness and lightweight of vehicles. However, it is difficult to predict the microstructure and mechanical properties of medium manganese steel parts after forming due to the TRIP (Transformation Induced Plasticity) effect. Therefore, the Barkhausen noise (MBN) detection is used to research the mechanism of TRIP effect on the medium manganese steel, which will help to develop a non-destructive testing method for the microstructure and mechanical properties of medium manganese steel parts. By comparing the variation rule of the MBN peak value of medium manganese steel and dual-phase steel DP1180 during the tensile process,it is found that the peak value of MBN signals increase continuously after the medium manganese steel is yielded due to the TRIP effect;Based on the O-C model, the stress-induced martensite transformation is considered, and a new strain-transformation model is proposed to calculate the martensite content of medium manganese steel in all stages of elasticity and plasticity. Combined with the detection data onto MBN signal during the tensile process of medium manganese steel and the new strain-phase transformation model, an MBN nondestructive testing method for the martensite content of medium manganese steel is established and compared with the traditional XRD test method. For the martensite content of the corner of medium manganese steel U-shaped parts after stamping, the results showed the error between the MBN testing method (6.56%, 9.94%) and the XRD testing method (7.42%, 9.26%) is less than 12%. © 2023, The Authors. All rights reserved.

关键词： Tensile testing

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Formation mechanism of basin-like depression defect in electric upsetting process of Ni80A superalloy

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Transactions of Nonferrous Metals Society of China 2022年第10期32卷 3276-3290页

作者： Guo-zheng QUAN Xue SHENG Kun YANG Yan-ze YU Wei XIONG Chongqing Key Laboratory of Advanced Mold Intelligent Manufacturing College of Materials Science and EngineeringChongqing UniversityChongqing 400044China State Key Laboratory of Materials Processing and Die&Mould Technology Huazhong University of Science and TechnologyWuhan 430074China Nanjing Jiepin Intelligent Technology Co. Ltd.Nanjing 210000China Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education Collaborative Innovation Center of Advanced Nuclear Energy TechnologyInstitute of Nuclear and New Energy TechnologyTsinghua UniversityBeijing 100084China

A kind of surface instability,basin-like depression defect companied by mixed grain structure at the bottom of large-scale valve during electric upsetting process,would significantly influence the microstructures and mechanical properties of *** order to analyze the forming process of the basin-like depression defect,a finite element model for the electric upsetting process of Ni80A superalloy was developed using multi-field and multi-scale coupling analysis ***,a series of parameters loading path schemes for force and current were designed by varying the initial value,peak value and value level,and their effects on basin-like depression and mixed grain structure were simulated and *** is concluded that the changes of heating speed and pressurization speed result in the different flow velocities between the inner and outer layers of billet,thus exerting the basin-like *** results also indicate that these defects can be optimized through the parameter coordination between force and ***,the validity and reliability of the finite element model were verified by physical experiments in electric upsetting process.

关键词： electric upsetting process defect Ni80A superalloy microstructure evolution mixed grain structure

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3D Positioning and Robot Assembly Method for Multi-plane Workpiece

3D Positioning and Robot Assembly Method for Multi-plane Wor...

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IEEE International Conference on Real-time Computing and Robotics (RCAR)

作者： Ruoyu Jia wKai Zhong Jintao Huang Xi Li Ruifeng Li Hua Luo Zhongwei Li State Key Lab. of Materials Processing and Die and Mould School of Materials Science and Engineering Huazhong University of Science and Technology Wuhan 430074 China Xi’an Saineng Aerospace Automation Technology Co. Ltd. Xi’an China

Aiming at the assembly of workpieces with multiple plane structures, this paper proposes a 3D visual positioning and robot assembly method. First, several planes are extracted by plane detection and outlier removal algorithms; then the poses of the plane point clouds are calculated by the oriented bounding box algorithm; finally, the target plane is found through the length and width constraints. Based on proper hand-eye calibration and motion planning, the method can achieve the workpieces’ recognizing, positioning and assembly accurately, meanwhile has high computational efficiency and strong robustness. As shown in the experiment results, for the recognition and positioning accuracy, the translation error of the proposed method is less than 0.2mm, and the rotation error is less than 0.2°; for the robot assembly accuracy, the translation error of the proposed method is less than 0.8mm and the rotation error is less than 0.4°. Therefore, the proposed method can successfully satisfy the requirement of robot assembly tasks.

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A Review on Discrete Element Method Simulation in Laser Powder Bed Fusion Additive Manufacturing

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Chinese Journal of Mechanical Engineering(Additive Manufacturing Frontiers) 2022年第1期1卷 70-82页

作者： Hui Chen Yajing Sun Weihao Yuan Shengyong Pang Wentao Yan Yusheng Shi State Key Lab of Materials Processing and Die&Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China Department of Mechanical Engineering National University of SingaporeSingapore 117575Singapore Department of Mechanical Manufacturing and Biomedical EngineeringTrinity College Dublinthe University of DublinDublin 2Ireland

Laser powder bed fusion(LPBF)is a popular metal additive manufacturing ***,the materials employed for LPBF are discrete and particulate metal ***,the discontinuous behaviors exhibited by the powder materials cannot be simulated solely using conventional continuum-based computational approaches,such as finite-element or finite-difference *** discrete element method(DEM)is a proven numerical method to model discrete matter,such as powder particles,by tracking the motion and temperature of individual ***,DEM simulation has gained popularity in LPBF ***,it has not been widely *** study reviews the existing applications of DEM in LPBF processing,such as powder spreading and fusion.A review of the existing literature indicates that DEM is a promising approach in the study of the kinetic and thermal fluid behaviors of powder particles in LPBF additive manufacturing.

关键词： Laser powder bed fusion Discrete element method Additive manufacturing Modelling Numerical simulation

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Improvement of Magnetic Properties and Hardness by Doing Mo to a Medium Entropy Alloy

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SSRN 2023年

作者： Xiang, Zhaolong Wang, Engang Wang, Tao An, Bailing Xin, Yan Lu, Jun Niu, Rongmei Han, Ke Li, Xi Shanghai Key Lab of Advanced High-temperature Materials and Precision Forming Shanghai Jiao Tong University Shanghai200240 China National High Magnetic Field Laboratory Florida State University TallahasseeFL32310 United States Northeastern University Shenyang110819 China State Key Laboratory of Materials Processing and Die & Mould Technology Huazhong University of Science and Technology Wuhan430074 China

In most technologies for improving material properties, the enhancement of one type of properties usually leads to the degradation of other properties. In this study, we demonstrated that we were able to simultaneously improve hardness, coercivity, and remanence by doping a FeCrCo Medium Entropy Alloy (MEA) with Mo in order to engineer the α→α1 + α2 spinodal decomposition of the MEA. Scanning Transmission Electron Microscopy (STEM) demonstrated that, in samples doped with Mo, decomposition led to an increase in the volume fraction of the α1 phase. Decomposition also led to an enhancement in the composition gap between the α1 and α2 phases, as well as to greater and greater lattice mismatch between the two phases at each stage of decomposition. Our first-principles calculations and Magnetic Force Microscopy (MFM) showed that the saturation magnetization gap between the α1 and α2 phases gradually increased, while the size of the magnetic domain decreased. Despite the fact that the magnetic moment of Mo atom was antiparallel to those of Co and Fe atoms in both α1 and α(according to first-principles calculations), Mo doping actually enhanced rather than diminished the magnetic properties of FeCrCo MEA while at the same time also increasing hardness. © 2023, The Authors. All rights reserved.

关键词： Spinodal decomposition

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3D/4D printed bio-piezoelectric smart scaffolds for next-generation bone tissue engineering

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International Journal of Extreme Manufacturing 2023年第3期5卷 236-262页

作者： Annan Chen Jin Su Yinjin Li Haibo Zhang Yusheng Shi Chunze Yan Jian Lu State Key Laboratory of Materials Processing and Die&Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074People’s Republic of China Engineering Research Center of Ceramic Materials for Additive Manufacturing Ministry of EducationWuhan430074People’s Republic of China Centre for Advanced Structural Materials Department of Mechanical EngineeringCity University of Hong KongPeople’s Republic of China Centre for Advanced Structural Materials City University of Hong Kong Shenzhen Research InstituteGreater Bay Joint DivisionShenyang National Laboratory for Materials ScienceShenzhen 518057People’s Republic of China CityU-Shenzhen Futian Research Institute Shenzhen 518045People’s Republic of China

Piezoelectricity in native bones has been well recognized as the key factor in bone ***,bio-piezoelectric materials have gained substantial attention in repairing damaged bone by mimicking the tissue’s electrical microenvironment(EM).However,traditional manufacturing strategies still encounter limitations in creating personalized bio-piezoelectric scaffolds,hindering their clinical ***-dimensional(3D)/four-dimensional(4D)printing technology based on the principle of layer-by-layer forming and stacking of discrete materials has demonstrated outstanding advantages in fabricating bio-piezoelectric scaffolds in a more complex-shaped ***,4D printing functionality-shifting bio-piezoelectric scaffolds can provide a time-dependent programmable tissue EM in response to external stimuli for bone *** this review,we first summarize the physicochemical properties of commonly used bio-piezoelectric materials(including polymers,ceramics,and their composites)and representative biological findings for bone ***,we discuss the latest research advances in the 3D printing of bio-piezoelectric scaffolds in terms of feedstock selection,printing process,induction strategies,and potential ***,some related challenges such as feedstock scalability,printing resolution,stress-to-polarization conversion efficiency,and non-invasive induction ability after implantation have been put ***,we highlight the potential of shape/property/functionality-shifting smart 4D bio-piezoelectric scaffolds in bone tissue engineering(BTE).Taken together,this review emphasizes the appealing utility of 3D/4D printed biological piezoelectric scaffolds as next-generation BTE implants.

关键词： 3D/4D printing bio-piezoelectric materials biomimetic scaffolds electrical microenvironment bone regeneration

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Surface Microstructure Refinement and Mechanical Properties of Gcr15 Steels Improved During Ultrasonic Surface Rolling Processing

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SSRN 2022年

作者： Xue, Xianmeng Xu, Shubo Ma, Xiquan Han, JuanJuan Zheng, Wei School of Materials Science and Engineering Shandong Jianzhu University Jinan250101 China State Key Laboratory of Material Forming and Mould & Die Technology Central China University of Technology Wuhan430025 China

As one of the most commonly used high chromium-bearing steels, GCr15 steel (AISI-52100) has high hardness, strength, wear resistance, and corrosion resistance. However, the surface of GCr15 steel is sensitive to failure behavior. In this paper, ultrasonic surface rolling processing (USRP) was used to strengthen GCr15-bearing steel. A finite element three-dimensional model of USRP was established to analyze the residual compressive stress and equivalent plastic strain distribution on the bearing steel surface. The microstructure, hardness, surface roughness, and corrosion resistance before and after USRP treatment were characterized by SEM, EBSD, X-ray diffraction (XRD), and electrochemical techniques. Results indicated that USRP treatment can significantly improve the material's surface microstructure and residual compressive stress distribution and obtain a plastic strain layer of about 60μm. After USRP treatment, the Kernel Average Misorientation (KAM) increased, and the dislocation activity was more intensive, resulting in aggregation near grain boundaries, and the percentage of LAGBs increased to 38.8%. Under the combined effect of surface grain refinement, residual compressive stress, and high glossy surface, the self-corrosion current density is reduced by two orders of magnitude, and the corrosion resistance is significantly improved. This investigation suggests a solution to the bearing failure problem and has implications for understanding the deformation mechanism of ultrasonic surface rolling processing. © 2022, The Authors. All rights reserved.

关键词： Corrosion resistance

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Study on Constitutive Model and Fracture Criterion of 7075 Aluminum Alloy at High Temperature

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SSRN 2023年

作者： Wang, Zijian Zhang, Xiaolei Gui, Jiangtao Geng, Huicheng Xiang, Chongchen Ding, Hanlin School of Iron and Steel Soochow University Suzhou215137 China Yangtze Delta Region Institute of Advanced Materials Suzhou215000 China State Key Lab of Materials Processing and Die and Mould Technology Huazhong University of Science and Technology Wuhan430074 China

Hot stamping has been widely used to solve the problems of spring back and cracking of aluminum alloy after cold forming. However, sheets are prone to failures like wrinkling and cracking during hot forming. Therefore, it is particularly important to establish a correct material model that can accurately reflect the deformation and fracture of the material. In this study, Tensile tests were conducted on the specimens at different temperatures, and Digital Image Correlation (DIC) was employed to obtain the specimen strain. The Yld2000-3d anisotropic yield criterion and the DF2014 fracture criterion were calibrated based on experiments and modeling, which were then used to characterize the anisotropy and fracture behavior of 7075 aluminum alloy, respectively. The specimens were also observed for fracture surface morphology. As the experiments and simulation results revealed, the 7075 aluminum alloy still had a more pronounced anisotropy at high temperatures. Finite element simulation was performed to obtain the parameters of the DF2014 fracture model at different temperatures. The results showed that the DF2014 fracture model could accurately predict the fracture behavior of the aluminum alloy. The specimens exhibited brittle fracture at room temperature, while the behavior changed to typical ductile fracture as the temperature rose. © 2023, The Authors. All rights reserved.

关键词： Anisotropy

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Modulation of Ti2Ni morphology in laser powder bed fused Ni-Ti alloys for excellent shape memory effect

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SSRN 2024年

作者： Ma, Bowen Lu, Haizhou Li, Jiayin Chen, Dongxu Jiang, Yuchuan Yang, Chao Li, Dongdong Zhang, Yuping State Key Laboratory for Materials Processing and Die and Mould Technology School of Materials Science and Engineering Huazhong University of Science and Technology Wuhan China School of Mechatronic Engineering Guangdong Polytechnic Normal University Guangzhou510665 China National Engineering Research Center of Near-net-shape Forming for Metallic Materials South China University of Technology Guangzhou510640 China School of Chemistry and Chemical Engineering Huazhong University of Science and Technology Wuhan China

NiTi alloy produced by laser powder bed fusion (LPBF) is often limited by uncontrolled non-equilibrium solidification, which generates non-uniform tissue such as Ti2Ni with irreversible effects on its mechanical and functional properties. To address this challenge, a layer-alternating LPBF (ALT-LPBF) method that programs hs changes along the building height was proposed for the first time. ALT-LPBF enables directional control over the morphology of Ti2Ni (from spherical to sub-ellipsoidal) by influencing inhomogeneous residual stress. Precise testing of the compositional fields within the melting pool and grains revealed that both peritectic and eutectic reactions are involved in Ti2Ni development, contributing to a deeper understanding of the mechanisms governing Ti2Ni formation during ALT-LPBF. Additionally, spherical Ti2Ni forms a coherent interface with B2 matrix, reducing stress concentration and promoting work hardening, through an elastic strain field. In contrast, sub-ellipsoidal Ti2Ni forms an incoherent interface, intensifying the stress field, promoting dislocation accumulation and inhibiting plastic deformation. The combination of spherical and sub-ellipsoidal Ti2Ni induced by ALT-LPBF enhances ultimate tensile strength to 850.6 MPa and shape memory effect 98.8%. This work lays the foundation for achieving ideal shape memory effect through ALT-LPBF and expands biomedical devices and smart materials applications. © 2024, The Authors. All rights reserved.

关键词： Tensile testing

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