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Hot Deformation Behavior and Processing Maps of 0.3C-15Cr-1Mo-0.5N High Nitrogen Martensitic Stainless Steel

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Acta Metallurgica Sinica(English Letters) 2020年第5期33卷 693-704页

作者： Xin Cai Xiao-Qiang Hu Lei-Gang Zheng dian-zhong Li Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences72 Wenhua RoadShenyang 110016China School of Materials Science and Engineering University of Science and Technology of China72 Wenhua RoadShenyang 110016China

Hot deformation behavior of 0.3 C-15 Cr-1 Mo-0.5 N high nitrogen martensitic stainless steel(HNMSS)was investigated in the temperature range of 1173-1473 K and at strain rates of 0.001-10 s-1 using a Gleeble 3500 thermal-mechanical *** true stress-strain curves of the studied HNMSS were measured and corrected to eliminate the effect of friction on the flow *** relationship between the flow stress and Zener-Hollomon parameter for the studied HNMSS wsa analyzed in the Arrhenius hyperbolic sine constitutive model by the law of Z=3.76×1015 sinh(0.004979σp)*** processing maps at different strains of the studied HNMSS were plotted,and its flow instability regions in hot working were also confirmed in combination with the microstructure ***,the optimal hot deformation parameters of the studied HNMSS could be suggested at T=1303-1423 K andε=5-10 s-1 or T=1273-1473 K andε=0.005-0.04 s-1.

关键词： High nitrogen martensitic stainless steel(HNMSS) Hot deformation Processing map Microstructure

Degeneration and rejuvenation of shape memory effect associated with the precipitation of coherent nano-particles in a Co-Ni-Si shape memory alloy

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Journal of Materials Science & Technology 2021年第17期76卷 150-155页

作者： Huabei Peng dian Wang Qi Liao Yuhua wen School of Mechanical Engineering Sichuan UniversityChengdu 610065China

In a solution treated Co-20Ni-6Si shape memory alloy,coherent nano-particles were precipitated after annealing at 873 K for 1 min,but the shape memory effect almost *** is attributed to that the coherent nano-particles not only suppressed the stress-induced face-centered cubic to close-packed hexagonal martensite transformation but also damaged the crystallographic reversibility of reverse martensite *** further annealing at 1073 K for 1 min,the shape memory effect was rejuvenated owing to the dissolution of ***,the recovery strain significantly increased to5.1%from the solution treatment of 3.1%after annealing at 1073 K for 1 min.

关键词： Shape memory alloys Martensitic phase transformation Defects Coherent nano-particles

Numerical Investigation on Residual Stresses of the Safe-End/Nozzle Dissimilar Metal Welded Joint in CAP1400 Nuclear Power Plants

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Acta Metallurgica Sinica(English Letters) 2019年第5期32卷 618-628页

作者： wen-Chao Dong dian-Bao Gao Shan-Ping Lu Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal Research Chinese Academy of Sciences Nuclear Power and Petro-chemical Business Group China First Heavy Industries

The residual stress evolution in a safe-end/nozzle dissimilar metal welded joint of CAP1400 nuclear power plants was investigated in the manufacturing process by finite element simulation. A finite element model, including cladding,buttering, post-weld heat treatment (PWHT) and dissimilar metal multi-pass welding, is developed based on SYSWELD software to investigate the evolution of residual stress in the aforementioned manufacturing process. The results reveal a large tensile axial residual stress, which exists at the weld zone on the inner surface, leads to a high sensitivity to stress corrosion cracking (SCC). PWHT process before dissimilar metal multi-pass welding process has a great in?uence on the magnitude and distribution of final axial residual stress. The risk of SCC on the inner surface of the pipe will increase if PWHT process is not taken into account. Therefore, such crucial thermal manufacturing process such as cladding, buttering and post-weld heat treatment, besides the multi-pass welding process, should be considered in the numerical model in order to accurately predict the distribution and the magnitude of the residual stress.

关键词： CAP1400 nuclear power plants Nozzle Safe-end Dissimilar metal welding Residual stress

Effect of aminoguanidine on caspase-3 expression in rat retina after ischemia-reperfusion injury

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International Journal of Ophthalmology(English edition) 2011年第3期4卷 259-261页

作者： Yang Yang, dian-wen Gao Department of Ophthalmology Shengjing Hospital China Medical University Shenyang 110021 Liaoning Province China Department of Orthopaedics Shengjing Hospital China Medical University Shenyang 110021 Liaoning Province China

AIM: To investigate the effect of aminoguanidine (AG) on the Expression of caspase-3 in rat retina after ischemia-reperfusion injury. METHODS: The rats were anesthetized with 30mg/kg sodium pentobarbital introperitoneal (ip) injections. After topical application of 10g/L dicaine, the anterior chamber was punctured with a 5-gauge needle connected to a bottle containing normal saline. Intraocular pressure was raised to 100 mmHg by elevating the saline container. The infusion needle was removed from the anterior chamber 60 minutes later. Reperfusion of the retinal vasculature was confirmed by fundus examination. AG 100mg/kg was ip injected in drug group. The rats were then euthanatized at 6, 24, and 72 hours after reperfusion, and their eyes were enucleated for immunohistochemistry. RESULTS: No specific staining was detected by using the caspase-3 antibody in the retina of control group. In ischemia group, the protein of caspase-3 was over-expressed at 6 hours and relieved at 24 hours and 72 hours, while with drug treatment, the expression of protein of caspase-3 was decreased at each time point. CONCLUSION: AG provides retinal protection against ischemia-reperfusion injury in rat retina, probably through an inducible NOS-dependent mechanism.

关键词： aminoguanidine ischemia-reperfusion caspase-3

DOA and Subarray-Interval Estimation for Arbitrarily Distributed UAV Swarm System

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China Communications 2023年第4期20卷 102-117页

作者： dian Fan Yue Zhu Jia You Zhe Wang Nan zhong The China Academy of Information and Communications Technology Beijing 100191China The China Academy of Railway Sciences Corporation Limited Beijing 100081China

In this paper,DOA and subarray-interval estimation are considered and applied to arbitrarily distributed unmanned aerial vehicle(UAV)swarm system,in which multiple small UAVs containing uniform linear array(ULA)are divided by unknown intervals because of dynamic *** parameters are taken to indicate the steering vector,namely,the direction of arrivals(DOAs)of target users,the intervals of UAVs,and the orientation angles of *** orientation angles are first estimated with an auxiliary user and the DOAs are obtained through a search free rooting method,despite the intervals among the ***,the intervals among UAVs can also be calculated via exhaustive when the number of target users are no less than *** further develop a low-complex method to reduce the computational complexity during subarray-interval *** deterministic Cramér-Rao bound(CRB)of the DOA,orientation angle and subarray-interval can be inferred in a closed ***,numerical instances are cited to verify the research results.

关键词： distributed subarray DOA orientation angle subarray-interval CRB

Micro-scale Cellular Automaton Modeling of Interface Evolution During Reaustenitization from Pearlite Structure in Steels

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Acta Metallurgica Sinica(English Letters) 2018年第7期31卷 713-722页

作者： Gang Shen Cheng-Wu Zheng Jian-Feng Gu dian-zhong Li Institute of Materials Modification and Modelling School of Materials Science and Engineering Shanghai Jiao Tong University Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Materials Genome Initiative Center Shanghai Jiao Tong University Shanghai Key Laboratory of Materials Laser Processing and Modification Shanghai Jiao Tong University

A modified cellular automaton model is developed to depict the interface evolution inside the cementite plus ferrite lamellar microstructures during the reaustenitization of a pearlite steel. In this model, migrations of both the austenite- ferrite and austenite-cementite interfaces coupled with the carbon diffusion and redistribution are integrated. The capil- laxity effect derived from local interface curvatures is also carefully considered by involving the concentration given by the phase diagram modified by the Gibbs-Thomson effect. This allows the interface evolution from a transient state to a steady state under different annealing conditions and various interlamellar spacings to be simulated. The proposed cellular automaton approach could be readily used to describe the kinetics of austenite formation from the lamellar pearlites and virtually reveal the kinematics of the moving interfaces from the microstructural aspect.

关键词： Austenite formation Lamellar pearlite Interface evolution Cellular automaton Microstructural modeling

A Line Search SQP-type Method with Bi-object Strategy for Nonlinear Semidefinite Programming

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Acta Mathematicae Applicatae Sinica 2022年第2期38卷 388-409页

作者： wen-hao FU zhong-wen CHEN School of Mathematical Sciences Suzhou University of Science and TechnologySuzhou 215009China School of Mathematical Sciences Soochow UniversitySuzhou 215006China

We propose a line search exact penalty method with bi-object strategy for nonlinear semidefinite *** each iteration,we solve a linear semidefinite programming to test whether the linearized constraints are consistent or *** search direction is generated by a piecewise quadratic-linear model of the exact penalty *** penalty parameter is only related to the information of the current iterate *** line search strategy is a penalty-free *** and local convergence are analyzed under suitable *** finally report some numerical experiments to illustrate the behavior of the algorithm on various degeneracy situations.

关键词： nonlinear semidefinite programming bi-object strategy global convergence rate of convergence

Gualou Guizhi decoction promotes neurological functional recovery and neurogenesis following focal cerebral ischemia/reperfusion

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Neural Regeneration Research 2018年第8期13卷 1408-1416页

作者： Jing Han Ji-Zhou Zhang Zhi-Feng zhong Zuan-Fang Li wen-Sheng Pang Juan Hu Li-dian Chen Institute of Materia Medica Fujian Academy of Traditional Chinese Medicine Fuzhou Fujian Province China Fujian University of Traditional Chinese Medicine Fuzhou Fujian Province China The Second People's Hospital of Fujian Province Fuzhou Fujian Province China

Recovery following stroke involves neurogenesis and axonal remodeling within the ischemic brain. Gualou Guizhi decoction （GLGZD） is a Chinese traditional medicine used for the treatment of post-stroke limb spasm. GLGZD has been reported to have neuroprotective effects in cerebral ischemic injury. However, the effects of GLGZD on neurogenesis and axonal remodeling following cerebral ischemia remain unknown. In this study, a rat model of focal cerebral ischemia/reperfusion was established by middle cerebral artery occlusion. Neurologi- cal function was assessed immediately after reperfusion using Longa＇s 5-point scoring system. The rats were randomly divided into vehicle and GLGZD groups. Rats in the sham group were given sham operation. The rats in the GLGZD group were intragastrically administered GLGZD, once daily, for 14 consecutive days. The rats in the vehicle and sham groups were intragastrically administered distilled water. Modified neurological severity score test, balance beam test and foot fault test were used to assess motor functional changes. Nissl staining was performed to evaluate histopathological changes in the brain. Immunofluorescence staining was used to examine cell proliferation using the marker 5-bromo-2＇-deoxyuridine （BrdU） as well as expression of the neural precursor marker doublecortin （DCX）, the astrocyte marker glial fibrillary acidic protein （GFAP） and the axon regeneration marker growth associated protein-43 （GAP-43）. GLGZD substan- tially mitigated pathological injury, increased the number of BrdU, DCX and GFAP-immunoreactive cells in the subventricular zone of the ischemic hemisphere, increased GAP-43 expression in the cortical peri-infarct region, and improved motor function. These findings suggest that GLGZD promotes neurological functional recovery by increasing cell proliferation, enhancing axonal regeneration, and in- creasing the numbers of neuronal precursors and astrocytes in the peri-infarct area.

关键词： nerve regeneration Gualou Guizhi decoction cell proliferation neurogenesis neuroblast astrocyte axon remodeling ischemic stroke Chinese medicine compound neural regeneration

Effect of Nb and Mo on the Microstructure, Mechanical Properties and Ductility-Dip Cracking of Ni–Cr–Fe Weld Metals

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Acta Metallurgica Sinica(English Letters) 2016年第10期29卷 928-939页

作者： Xu Zhang dian-zhong Li Yi-Yi Li Shan-Ping Lu Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences School of Materials Science and Engineering University of Science and Technology of China Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal Research Chinese Academy of Sciences

A series of Ni-Cr-Fe welding wires with different Nb and Mo contents were designed to investigate the effect of Nb and Mo on the rnicrostructure, mechanical properties and the ductility-dip cracking susceptibility of the weld metals by optical microscopy （OM）, scanning electron microscopy, X-ray diffraction as well as the tensile and impact tests. Results showed that large Laves phases formed and distributed along the interdendritic regions with high Nb or Mo addition. The Cr-carbide （M23C6） was suppressed to precipitate at the grain boundaries with high Nb addition. Tensile testing indicates that the ultimate strength of weld metals increases with Nb or Mo addition. However, the voids formed easily around the large Laves phases in the interdendritic area during tensile testing for the weld metal with high Mo content. It is found that the tensile fractographs of high Mo weld metals show a typical feature of interdendritic fracture. The high Nb or Mo addition, which leads to the formation of large Laves phases, exposes a great weakening effect on the impact toughness of weld metals. In addition, the ductility-dip cracking was not found by OM in the selected cross sections of weld metals with different Nb additions. High Nb addition can eliminate the ductility-dip cracking from the Ni-Cr-Fe weld metals effectively.

关键词： Nb Mo Laves phase Microstructure Mechanical properties