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THE COUPLED FEM ANALYSIS OF THE TRANSIENT TEMPERATURE FIELD DURING INERTIA FRICTION WELDING OF GH4169 ALLOY

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Acta Metallurgica Sinica(English Letters) 2007年第4期20卷 301-306页

作者： L.W. Zhang J.B. Pei Q.Z. Zhang C.D. liu W.H. Zhu S. Qu J.H. Wang The State Key Laboratory for Materials Modification by Laser Ion and Electron Beams Dalian University of Technology Dalian 116023 China School of Materials Science and engineering Dalian University of Technology Dalian 116023 China shenyang li ming aero-engine group corporation Shenyang 110043 China

The inertia friction welding process is a non-linear process because of the interaction between the temperature field and the material properties as well as the friction force. A thermo-mechanical coupled finite element model is established to simulate the temperature field of this process. The transient temperature distribution during the inertia friction welding process of two similar workpieces of GH4169 alloy is calculated. The region of the circular cross-section of the workpiece is divided into a number of four-nodded isoparametric elements. In this model, the temperature dependent thermal properties, time dependent heat inputs, contact condition of welding interface, and deformation of the flash were considered. At the same time, the convection and radiation heat losses at the surface of the workpieces were also considered. A temperature data acquisition system was developed. The temperature at some position near the welding interface was measured using this system. The calculated temperature agrees well with the experimental data. The deformation of the flash and the factor affecting the temperature distribution at the welding interface are also discussed.

关键词： inertia friction welding temperature field numerical simulation finite element method

Electrochemical Behavior of Oxide Films of Stainless Steel in 40 kHz Sonicated Sulphate Electrolytes

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Chinese Journal of aeronautics 2007年第2期20卷 148-152页

作者： ZHU li-qun li Min-wei WANG Hui School of Materials Science and engineering Beij＇ing University of Aeronautics and Astronautics Beijing 100083 China shenyang liming aero-engine group corporation Shenyang 110043 China

This paper describes effects of 40 kHz ultrasound on the oxide films of stainless steel in sulphate electrolytes so as to determine the transmitted power and to characterize mass transfer and peak current density on the electrode surface. Emphasis was mainly laid on electrochemical oxidations and peeling mechanism of oxide films in sonicated sulphate solutions （0.5 and 1.0 mol/L）. Polarization voltammetry, current response traces and SEM analysis were carded out in order to provide full information as to oxide films surface. Results shows that the rate of electrochemical oxidation, the shape of polarization curves and the surface micrographs in sonicated sulphate electrolytes are different from those obtained without introduction of ultrasound. It is concluded that ultrasound can change the electro-chemical behavior of oxide films by its cavitaion effects, which would produce transient mechanical impulsive force and enhance electrochemical reactions.

关键词： stainless steel oxide films electrolysis ultrasound cavitation

Cyclic oxidation behavior of β-NiAlDy alloys containing varying aluminum content at 1200℃

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Progress in Natural Science:Materials International 2012年第4期22卷 311-317页

作者： Dongqing li Lu Wang Hui Peng Xiaoyu Zhao Hongbo Guo Shengkai Gong School of Materials Science and engineering Beihang University shenyang liming aero-engine group corporation Ltd. AVICShenyang 110043China

β-NiAlDy cast alloys containing varying aluminum content were prepared by arc-melting. The microstructures and cyclic oxidation behavior of the alloys at 1200 ℃ were investigated. Grain refinement was achieved by increasing aluminum content in the alloy, which is beneficial to selective oxidation. The Ni-55Al-0.1Dy alloy showed excellent cyclic oxidation resistance due to the formation of a continuous, dense and slow-growing oxide scale. In contrast to this, severe internal oxidation as well as large void formation at the scale/alloy interface occurred in the Ni-45Al-0.1Dy alloy. The aluminum content dependence of the reactive element effects in β-NiAlDy was established that Dy doping strengthened the scale/alloy interface by pegging mechanism in high-aluminum alloys but accelerated internal oxidation in low-aluminum alloys during high-temperature exposure.

关键词： β-NiAl Reactive elements Dysprosium Aluminum content High-temperature oxidation

Evolution of Grain Selection in Spiral Selector during Directional Solidification of Nickel-base Superalloys

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Journal of Materials Science & Technology 2011年第2期27卷 118-126页

作者： Xiangbin Meng Jinguo li Tao Jin Xiaofeng Sun Changbo Sun Zhuangqi Hu Institute of Metal Research Chinese Academy of SciencesShenyang 00China Graduate School of Chinese Academy of Sciences Beijing 000China shenyang liming aero-engine(group) corporation Ltd. Aviation Industry Corporation of China(AVIC)Shenyang 110043China

The process of grain selection in the spiral selector was investigated by both a ProCAST simulation based on a cellular automaton finite element（CAFE） model and experimental *** results show that the height of starter block,the spiral diameter and initial angle play an important role in grain *** dimension of selector should be maintained in a stable range to optimize the grain orientation and select a single crystal efficiently.A selector which can efficiently select a single crystal had been successfully *** orientation fluctuation in the spiral part was also studied by means of the variation of thermal condition.

关键词： Ni-base single crystal superalloys Grain selection Directional solidification

Effect of Solution Treatment on the Microstructure and Mechanical Properties of Sand-Cast Mg–9Gd–4Y–0.5Zr Alloy

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Acta Metallurgica Sinica(English Letters) 2018年第2期31卷 189-198页

作者： Jing-li li Na Zhang Xiao-Xuan Wang Di Wu Rong-Shi Chen The group of Magnesium Alloys and Their Applications Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China School of Materials Science and engineering University of Science and Technology of China Hefei 230026 China AVIC shenyang liming aero--engine group corporation Shenyang 110043 China

Sand-cast Mg–9Gd–4Y–0.5 Zr（wt%） alloy was solution-treated at 500–565 ℃ in the time range of 0.5–30 h in air or vacuum to investigate its microstructure evolution and mechanical properties. The results showed that solution treatment temperature had a significant influence on the dissolving rate of eutectic phase and grain growth. Taken both of them into consideration, 510–520 ℃ was considered to be the optimum solution treatment temperature range for this *** should be noted that the trace（0.4–0.9 vol%） and insoluble cuboid-shaped phase precipitated during solution treatment was identified to be YH2, of which the hydrogen was thought to come from both the melting and solution heating *** addition, the 3D morphology and dissolving process of Mg24（Gd,Y）5 eutectic phases in the as-cast alloy were also discussed via in-situ observation under X-ray tomography.

关键词： Mg-Gd-Y-Zr alloy Solution treatment Microstructure Rare-earth hydride

Modes of Grain Selection in Spiral Selector during Directional Solidification of Nickel-base Superalloys

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Journal of Materials Science & Technology 2012年第3期28卷 214-220页

作者： Xiangbin Meng Qi Lu Jinguo li Tao Jin Xiaofeng Sun Jun Zhang ZhongqiangChen Yanhui Wang Zhuangqi Hu Institute of Metal Research Chinese Academy of SciencesShenyang 110016China Graduate School of Chinese Academy of Sciences Beijing 100049China State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi'an 710072China Aviation Industry corporation of China(AVIC)shenyang liming aero-engine(group)corporation LTD. Shenyang 110043China

The modes of grain selection in spiral selector were investigated by both a ProCAST simulation and experimental *** results show that the efficiency of grain selection in starter block is associated with the geometry *** the early stage of grain selection,the optimization of grain orientation is dominated by competitive grain growth,but the optimization of grain orientation in starter block is gradually dominated by geometry shape at the later stage of grain ***,the spiral part could also optimize the orientation of the selected single crystal when the initial angle is large enough,and the single crystal selection in spiral parts with different pitch lengths and initial angles is dominated by different *** simulation results agree well with experimental ones.

关键词： Ni-base single crystal superalloys Competitive grain growth Geometry shape Directional solidification Spiral selector

Creep Behavior of Fusion Zone and Base Metal of the Electron Beam Weldments of a Near-alpha Titanium Alloy

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Journal of Materials Science & Technology 2010年第6期26卷 564-571页

作者： Zhiyong Chen Jinwei li Jie liu Qingjiang Wang Jianrong liu Rui Fang Division of Titanium alloys Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Research Department of High Energy Density Beam Processing Technology Beijing Aeronautical Manufacturing Technology Research Institute Beijing 100024 China AVIC shenyang liming aero-engine (group) corporation LTD Shenyang 110043 China

The high temperature creep behavior of fusion zone （FZ） and of a near-alpha titanium alloy Ti-60 has been investigated. base metal （BM） of the electron beam weldments While the BM shows a fully transformed, coarse primary β grains with large colonies consisting of aligned α lamellar, the FZ exhibits thin martensitic α′ platelets in the columnar β grains. The creep results show that the steady state creep rates of FZ follow the power-law creep, with the stress exponents obtained in the range from 5.6 （550℃） to 5.9 （600℃）, and corrected activation energies of 309-352 kJ/mol; the stress exponents of BM exhibit different values when the creep testing stress and temperature alternate. The values of 2.4-3.2 are obtained when the stresses are under 220 MPa or the temperature is 550℃, also an exponent of 6.6 is achieved at stresses above 220 MPa at 600℃. The corrected activation energies of BM corresponding to the stress exponents are 123-161 kJ/mol （n=2.4-3.2） and 344 kJ/mol （n=6.6）. The creep mechanisms of FZ and BM have been discussed in light of the creep microstructures, activation energies and the stress exponents. The creep mechanisms of FZ is the diffusion controlled dislocation climb, the creep of BM is controlled by ＇solute drag＇ creep and dislocation climb when the stress and temperature are different. Transmission electron microscopy （TEM） observations of the dislocation structures of crept specimens are presented to give some supports for the creep behavior of FZ and BM. In addition to the creep mechanism of dislocation movement, the interface sliding has been found to play an important role during creep of FZ.

关键词： Steady state creep Stress exponent Activation energy Electron beam welding Near-alpha titanium alloy

Effects of Shot Peening Process on Thermal Cycling lifetime of TBCs Prepared by EB-PVD

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Chinese Journal of aeronautics 2007年第2期20卷 145-147页

作者： ZHOU Zhao-hui GONG Sheng-kai li He-fei XU Hui-bin ZHANG Chun-gang WANG Lu School of Materials Science and engineering Beij＇ing University of Aeronautics and Astronautics Beij＇ing 100083 China shenyang liming.4ero-engine group corporation Shenyang 110043 China

Conventional two-layered thermal barrier coatings （TBCs） are prepared by electron beam physical vapor deposition （EB-PVD） with ZrO2-8 wt% Y2O3 （8YSZ） as top coat and CoCrAlY as bond coat on disk-shaped Ni based super-alloy. In this paper, three kinds of shot peening process with different lengths of operating time were adopted for bond coating. As a result, changes took place in its surface roughness and the surface micro-hardness. A thermal cycling test at 1 273 Kx55 rain and another at room temperature for 5 min were performed to study the effects of shot peening process on the thermal cycling lifetime of TBCs. It is found that a moderate shot peening process will be able to prolong the life time. The oxidation dynamic of the as-processed TBCs basically accords with the parabolic rule, and the oxidation test also attests to the spallation between YSZ and thermal growth oxide （TGO） responsible mainly for the failure of TBCs.

关键词： thermal cycling lifetime shot peening thermal barrier coatings (TBCs)

Hot deformation behavior of GH4945 superalloy using constitutive equation and processing map

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Journal of Iron and Steel Research International 2017年第6期24卷 625-633页

作者： Zhao-xia Shi Xiao-feng Yan Chun-hua Duan Jin-gui Song ming-han Zhao Jue Wang High Temperature Materials Research Institute Central Iron and Steel Research Institute Beijing 100081 China Beijing Key Laboratory of Advanced High Temperature Materials Central Iron and Steel Research Institute Beijing 100081China shenyang liming aero-engine (group) corporation Ltd. Shenyang 110043 Liaoning China School of Materials Science and engineering Nanjing Institute of Technology Nanjing 211167 Jiangsu China

The hot deformation behavior of GH4945 superalloy was investigated by isothermal compression test in the temperature range of 1000--1200 ℃with strain rates of 0.001 10.000 s 1 toa total strain of 0.7. Dynamic recrystallization is the primary softening mechanism for GH4945 superalloy during hot deformation. The constitutive equation is established, and the calculated apparent activation energy is 458. 446 kJ/moh The processing maps at true strains of 0.2, 0.4 and 0.6 are generally similar, dem- onstrating that strain has little influence on processing map. The power dissipation efficiency and in- stability factors are remarkably influenced by deformation temperature and strain rate. The optimal hot working conditions are determined in temperature range of 1082 -1131 ℃ with strain rates of 0.004--0.018 s-1. Another domain of1134--1150 ℃ and 0. 018 0.213s ^- can also be selected as the optimal hot working conditions. The initial grains are replaced by dynamically reerystallized ones in optimal domains. The unsafe domains locate in the zone with strain rates above 0, 274 s^- 1, mainly characterized by uneven microstructure. Hot working is not recommended in the unsafe domains.

关键词： Hot deformation behaviorConstitutive equationProcessing mapGH4945 superalloy