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Flow softening behavior and microstructure evolution of Al-5Zn-2Mg aluminum alloy during dynamic recovery 被引量:13
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作者 李落星 王冠 +1 位作者 刘杰 姚再起 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2014年第1期42-48,共7页
The flow stress behavior and microstructure development of Al-5Zn-2Mg (7005) aluminum alloy were studied by hot compression tests at deformation temperatures between 300-500 &#176;C and strain rates between 0.05-50... The flow stress behavior and microstructure development of Al-5Zn-2Mg (7005) aluminum alloy were studied by hot compression tests at deformation temperatures between 300-500 &#176;C and strain rates between 0.05-50 s-1. The deformed structures of the samples were observed by optical microscopy (OM), transmission electron microscopy (TEM) and electron backscattering diffraction (EBSD) analysis. The calculated activation energy is 147 kJ/mol, which is very close to the activation energy for lattice self-diffusion in aluminum (142 kJ/mol). Dynamic recovery is the dominant restoration mechanism during the deformation. At high strain rate of 50 s-1, temperature rise due to deformation heating leads to a significant flow softening. Microstructure observations indicated that the remaining softening after deformation heating correction at high strain rate and the softening observed at high temperature are associated with grain coarsening induced by grain boundary migration during dynamic recovery process. 展开更多
关键词 7005 aluminum alloy DEFORMATION dynamic recovery flow softening microstructure evolution
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Dynamic recovery and dynamic recrystallization of NiTi shape memory alloy under hot compression deformation 被引量:12
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作者 江树勇 张艳秋 赵亚楠 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第1期140-147,共8页
Mechanical behavior of nickel?titanium shape memory alloy(NiTi SMA) under hot deformation was investigated according to the true stress—strain curves of NiTi samples under compression at the strain rates of 0.001-... Mechanical behavior of nickel?titanium shape memory alloy(NiTi SMA) under hot deformation was investigated according to the true stress—strain curves of NiTi samples under compression at the strain rates of 0.001-1 s-1 and at the temperatures of 600?1000℃.Dynamic recovery and dynamic recrystallization of NiTi SMA were systematically investigated by microstructural evolution.The influence of the strain rates,the deformation temperatures and the deformation degree on the dynamic recovery and dynamic recrystallization of NiTi SMA was obtained as well.NiTi SMA was characterized by the combination of dynamic recovery and dynamic recrystallization at 600℃ and 700℃,but the complete dynamic recrystallization occurred at other deformation temperatures.Increasing the deformation temperatures or decreasing the stain rates leads to larger equiaxed grains.The deformation degree has an important influence on the dynamic recrystallization of NiTi SMA.There exists the critical deformation degree during the dynamic recrystallization of NiTi SMA,beyond which the larger deformation degree contributes to obtaining the finer equiaxed grains. 展开更多
关键词 NiTi alloy shape memory alloy dynamic recovery dynamic recrystallization hot deformation
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Dynamic test on waste heat recovery system with organic Rankine cycle 被引量:3
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作者 王志奇 刘力文 +1 位作者 夏小霞 周乃君 《Journal of Central South University》 SCIE EI CAS 2014年第12期4607-4612,共6页
Dynamic performance is important to the controlling and monitoring of the organic Rankine cycle(ORC) system so to avoid the occurrence of unwanted conditions. A small scale waste heat recovery system with organic Rank... Dynamic performance is important to the controlling and monitoring of the organic Rankine cycle(ORC) system so to avoid the occurrence of unwanted conditions. A small scale waste heat recovery system with organic Rankine cycle was constructed and the dynamic behavior was presented. In the dynamic test, the pump was stopped and then started. In addition, there was a step change of the flue gas volume flow rate and the converter frequency of multistage pump, respectively. The results indicate that the working fluid flow rate has the shortest response time, followed by the expander inlet pressure and the expander inlet temperature.The operation frequency of pump is a key parameter for the ORC system. Due to a step change of pump frequency(39.49-35.24 Hz),the expander efficiency and thermal efficiency drop by 16% and 21% within 2 min, respectively. Besides, the saturated mixture can lead to an increase of the expander rotation speed. 展开更多
关键词 organic Rankine cycle waste heat recovery dynamic performance
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DYNAMIC RECOVERY AND DYNAMIC RECRYSTALLIZATION OF 7005 ALUMINIUM ALLOY DURING HOT COMPRESSION 被引量:33
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作者 J. Shen S. S. Xie and J. H. tang (General Research Institute for Non - ferrous Metals,Beijing 100088, China) 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2000年第1期379-386,共8页
Dynamic recovery and dynamic recrystallizatin behaviors of AA7005 aluminium alloy (Al - Zn - Mg) during hot compression are investigated by isothermal compression testing.The interdependence of flow stress,stress, s... Dynamic recovery and dynamic recrystallizatin behaviors of AA7005 aluminium alloy (Al - Zn - Mg) during hot compression are investigated by isothermal compression testing.The interdependence of flow stress,stress, strain rate,true strain and deformation temperature for the alloy is analyzed by introduc- ing Zener-Hollomon parameter. A steady - state flow of the 7005 alloy is confirmed to be a thermal- ly activated process.which is governed by rate-controlling mechanisms of dislocations.A hyperbolic sine relationship can satisfactorily correlate temperature, strain rate with flow stress through an Arrhe- nius term that involves thermal activation parameters. The dynamic recovery mechanisms of the alloy are discussed.Cross- slip of jogged screw dislocations is the main dynamic recovery mechanism over the deformation temperatures and strain rates.Subgrains are highly developed in the originally elongat- ed grains.The size of the subgrain increases with decrease of the natural logarithm of Zener- Hol - lomon parameter.Local dynamic recrystallization is operative when the alloy is deformed at temperature of 500℃ and strain rate of 0. 001s - 1. 展开更多
关键词 compression flow stress dynamic recovery dynamic recrystallization restoration mechanism
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Analysis on Dynamic Dielectric Recovery and Statistical Property of Vacuum Circuit-Breakers with Multi-Breaks
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作者 廖敏夫 段雄英 邹积岩 《Journal of Beijing Institute of Technology》 EI CAS 2004年第1期103-108,共6页
Based on the dynamic dielectric recovery process in the vacuum gaps in series, investigations were made on post-arc insulation state in double and multi-breaks operation in high voltage power system. From the research... Based on the dynamic dielectric recovery process in the vacuum gaps in series, investigations were made on post-arc insulation state in double and multi-breaks operation in high voltage power system. From the research on the breakdown weak points in high voltage vacuum gaps, their turnout and distribution, some theoretic work were made to set up the models for describing the statistical property of multi-breaks vacuum circuit-breakers' breakdown and post-arc re-strike, which can be used for explaining the mechanism of the improvement in the breaking capacity of multi-breaks units compared with that of single-break ones which have the same equivalent gap length. The advantages of vacuum breakers with multi-breaks are proposed. 展开更多
关键词 multi-breaks dynamic dielectric recovery breakdown weak points
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Characterization of dynamic microstructure evolution during hot deformation of Al-4.10Cu-1.42Mg-0.57Mn-0.12Zr alloy 被引量:1
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作者 刘灿 张辉 蒋福林 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2014年第11期3477-3485,共9页
The Al?4.10Cu?1.42Mg?0.57Mn?0.12Zr alloy was compressed to different strains at deformation temperature of 300 oC and strain rate of 10 s?1 on Gleeble?1500 system. The dynamic complex microstructures evolutions were i... The Al?4.10Cu?1.42Mg?0.57Mn?0.12Zr alloy was compressed to different strains at deformation temperature of 300 oC and strain rate of 10 s?1 on Gleeble?1500 system. The dynamic complex microstructures evolutions were investigated by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The true stress?true strain curves exhibited a peak stress at critical strain, after which the flow stresses decreased monotonically, showing a dynamic flow softening. As the strain increased, the dislocation tangled to cell structure and sub-grain structure, which indicated the occurrence of dynamic recovery during deformation. Dynamic precipitations ofS (Al2CuMg),θ (Al2Cu) and Al3Zr phase were accelerated and coarsened by deformation. ContinuousS phases precipitated in the Al matrix and discontinuousS phases were found to be nucleated near the Al3Zr phase and at the sub-grain boundary. The flow softening mechanism was resulted from the reduction of dislocation density which attributed to dynamic recovery and precipitates coarsening. 展开更多
关键词 aluminum alloy hot deformation flow softening dynamic recovery dynamic precipitation
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Dynamic recrystallization of electroformed copper liners of shaped charges in high-strain-rate plastic deformation
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作者 WenhuaiTian QiSun 《Journal of University of Science and Technology Beijing》 CSCD 2002年第5期343-346,共4页
The microstructures in the electroformed copper liners of shapedcharges after high-strain-rate plastic deformation were in-vestigated by transmission electron microscopy(TEM). Meanwhile, theorientation distribution of... The microstructures in the electroformed copper liners of shapedcharges after high-strain-rate plastic deformation were in-vestigated by transmission electron microscopy(TEM). Meanwhile, theorientation distribution of the grains in the recovered slug wasexamined by the electron backscattering Kikuchipattern(EBSP)technique. EBSP analysis illustrated that unlike theas-formed electro- formed copper liners of shaped charges the grainorientations in the recovered slug are distributed along randomly allthe directions after undergoing heavily strain deformation athigh-strain rate. Optical microscopy shows a typicalrecrystallization structure, and TEM exam- ination revealsdislocation cells existed in the thin foil specimen. These resultsindicate that dynamic recovery and recrystallization occur duringthis plastic deformation process, and the associated deformationtemperature is considered to be higher than 0.6 times the meltingpoint of copper. 展开更多
关键词 ELECTROFORMATION high-strain-rate deformation dynamic recovery andrecrystallization transmission electron microscopy
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Hot deformation behavior of high Ti 6061 Al alloy 被引量:3
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作者 陈微 官英平 王振华 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2016年第2期369-377,共9页
The hot deformation behavior of a high Ti 6061 aluminum alloy in the temperature range from 350 to 510 ℃ and strain rate range from 0.001 to 10 s^-1 was investigated using stress-strain curve analysis, processing map... The hot deformation behavior of a high Ti 6061 aluminum alloy in the temperature range from 350 to 510 ℃ and strain rate range from 0.001 to 10 s^-1 was investigated using stress-strain curve analysis, processing map, transmission electron microscopy and electron backscatter diffraction analysis. The results show that the peak stress decreases with increasing deformation temperatures and decreasing strain rate. The average deformation activation energy is 185 kJ/mol in the parameter range investigated. The flow stress model was constructed. The main softening mechanism is dynamic recovery. The processing map was obtained using dynamic material model, and the suggested processing window is 400-440℃ and 0.001-0.1 s^-1. 展开更多
关键词 6061 A1 alloy hot deformation dynamic recovery hot processing map DISLOCATION
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Microstructure and Deformation Behavior of Ti-10V-2Fe-3Al Alloy during Hot Forming Process 被引量:1
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作者 管仁国 ZHAO Zhanyong +1 位作者 Choi KS Lee CS 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2015年第6期1332-1337,共6页
The microstructure evolution and formability of Ti-10V-2Fe-3Al alloy related to the initial microstructures and processing variables were investigated during hot forming process. The experimental results show that the... The microstructure evolution and formability of Ti-10V-2Fe-3Al alloy related to the initial microstructures and processing variables were investigated during hot forming process. The experimental results show that the α-phase growth is controlled by solute diffusion during the heat treatment processes. Four different microstructures were established by combinations of several heat treatments, and Ti-10V-2Fe-3Al alloy shows excellent formability both above and below the β transus temperature. The alloy possesses low deformation resistance and active restoration mechanism during the deformation. A constitutive equation describing the hot deformation behavior of Ti-10V-2Fe-3Al alloy was obtained. Higher fl ow stress was observed for the acicular morphology of α phase in microstructures with large aspect ratios as compared with that of small aspect ratios. Due to the dynamic recovery in soft β phase, and the dynamic recrystallization and breakage of acicular α-phase, fl ow softening occurred signifi cantly during deformation. Dynamic recrystallization also occurred especially in the severely deformed regions of forged parts. 展开更多
关键词 Ti-10V-2Fe-3Al alloy microstructure evolution hot forging constitutive equation recovery dynamic recrystallization
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Earth gravity field solution with combining CHAMP and GRACE data
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作者 Tianhe Xu Lei Ren Ruru Gao 《Geodesy and Geodynamics》 2017年第4期246-252,共7页
Satellite gravity data fusion with multi-type and huge-amount is one of the hot topics in physical geodesy. After a brief review of dynamic approach, the CHAMP-only and GRACE-only gravity fields by using HL-SST and LL... Satellite gravity data fusion with multi-type and huge-amount is one of the hot topics in physical geodesy. After a brief review of dynamic approach, the CHAMP-only and GRACE-only gravity fields by using HL-SST and LL-SST data from 2003 to 2009 are recovered respectively. An combination strategy of CHAMP and GRACE data by using Helmert variance component estimation (VCE) is proposed based on normal equation level fusion. Three gravity field models with 150° and order by CHAMP-only data, GRACE-only data and combining CHAMP and GRACE data from 2003 to 2009 are recovered. The comparisons between our recovered models and those latest released models were performed. The external accuracy validations using marine gravity anomalies from DTU13 products and height anomalies from GPS/leveling data are also conducted in this paper. The results show that long-term CHAMP data do contribute to the accuracy improvement of gravity field solution. The accuracy of the combined model using CHAMP and GRACE data is better than those of the individuals and comparative to the models published by international groups. 展开更多
关键词 CHAMP GRACE Gravity field recovery dynamic approach
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Microstructure evolution of 7050 aluminum alloy during hot deformation 被引量:17
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作者 李俊鹏 沈健 +2 位作者 闫晓东 毛柏平 闫亮明 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2010年第2期189-194,共6页
Hot compression of 7050 aluminum alloy was performed on Gleeble 1500D thermo-mechanical simulator at 350 ℃ and 450 ℃ with a constant strain rate of 0.1 s-1 to different nominal strains of 0.1, 0.3 and 0.7. Microstru... Hot compression of 7050 aluminum alloy was performed on Gleeble 1500D thermo-mechanical simulator at 350 ℃ and 450 ℃ with a constant strain rate of 0.1 s-1 to different nominal strains of 0.1, 0.3 and 0.7. Microstructures of 7050 alloy under various compression conditions were observed by TEM to investigate the microstructure evolution process of the alloy deformed at various temperatures. The microstructure evolves from dislocation tangles to cell structure and subgrain structure when being deformed at 350 ℃, of which dynamic recovery is the softening mechanism. However, continuous dynamic recrystallization (DRX) occurs during hot deformation at 450 ℃, in which the main nucleation mechanisms of DRX are subgrain growth and subgrain coalescence rather than particle-simulated nucleation (PSN). 展开更多
关键词 microstructure evolution dynamic recovery dynamic recrystallization hot deformation 7050 alloy
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Deformation behavior and microstructure of an Al-Zn-Mg-Cu-Zr alloy during hot deformation 被引量:10
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作者 Liang-ming Yan Jian Shen Jun-peng Li Zhou-bing Li Xiao-dong Yan 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2010年第1期46-52,共7页
The hot deformation behavior and microstructures of Al-7055 commercial alloy were investigated by axisymmetric hot compres- sion at temperatures ranging from 300℃ to 450℃ and strain rates from 10^-2 to 10 s^-1, resp... The hot deformation behavior and microstructures of Al-7055 commercial alloy were investigated by axisymmetric hot compres- sion at temperatures ranging from 300℃ to 450℃ and strain rates from 10^-2 to 10 s^-1, respectively. Microstructures of deformed 7055 alloy were investigated by transmission electron microscopy (TEM). The dependence of peak stress on deformation temperature and strain rate can be expressed by the hyperbolic-sine type equation. The hot deformation activation energy of the alloy is 146 kJ/mol. Moreover, the flow stress curves predicted by the modified constitutive equations are reasonably consistent with the experimental results, which confirms that the proposed deformation constitutive equations can provide evidence for the selection of hot forming parameters. TEM results indicate that dy- namic recovery is the main softening mechanism during hot deformation. 展开更多
关键词 aluminum alloys dynamic recovery hot compression deformation behavior constitutive equation
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Relationship between microstructure and mechanical properties of 5083 aluminum alloy thick plate 被引量:12
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作者 Xin-wei SHE Xian-quan JIANG +4 位作者 Pu-quan WANG Bin-bin TANG Kang CHEN Yu-jie LIU Wei-nan CAO 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2020年第7期1780-1789,共10页
The microstructure and mechanical properties of 105 mm thick 5083 aluminum alloy hot rolled plate were investigated by metallurgical microscope, scanning electron microscope and tensile testing machine, and three majo... The microstructure and mechanical properties of 105 mm thick 5083 aluminum alloy hot rolled plate were investigated by metallurgical microscope, scanning electron microscope and tensile testing machine, and three major characteristic problems in mechanical properties inhomogeneity were explained. The results show that the mechanical properties of the rolled plate are inhomogeneous along the thickness direction. From the surface to the center, the strength shows an inverted "N" shape change and the elongation presents a semi "U" shape change. Several similar structural units composed of long fibrous grains(LFG) and short fibrous grains bands(SFGB) exist in a special layer(Layer 2) adjacent to the surface. This alternating layered distribution of LFG and SFGB is conducive to improving the plasticity by dispersing the plastic deformation concentrated on the boundary line(BL) between them. However, their different deformability will cause the alternation of additional stresses during the hot rolling, leading to the strength reduction. The closer the location to the center of the plate is, the more likely the recovery rather than the recrystallization occurs. This is the possible reason for the unnegligible difference in strength near the central region(Layer 4 and Layer 5). 展开更多
关键词 aluminum alloy thick plate mechanical properties INHOMOGENEITY fibrous grains dynamic recovery dynamic recrystallization
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Multi-stage Dynamic Post-disaster Recovery Strategy for Distribution Networks Considering Integrated Energy and Transportation Networks 被引量:15
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作者 Xinyi Jiang Jian Chen +1 位作者 Ming Chen Zhen Wei 《CSEE Journal of Power and Energy Systems》 SCIE CSCD 2021年第2期408-420,共13页
To improve the resilience of distribution networks(DNs),a multi-stage dynamic recovery strategy is proposed in this paper,which is designed for post-disaster DN considering an integrated energy system(IES)and transpor... To improve the resilience of distribution networks(DNs),a multi-stage dynamic recovery strategy is proposed in this paper,which is designed for post-disaster DN considering an integrated energy system(IES)and transportation network(TN).First,the emergency response quickly increases the output of gas turbines(GTs)in the natural gas network(NGN),and responsively reconfigures the DN in microgrids,to maximize the amount of loads to be restored.The single-commodity flow model is adopted to construct spanning tree constraints.Then,in the second stage of energy storage recovery,mobile energy storage systems(MESSs)are deployed to cover the shortages of power demands,i.e.,to further restore the loads after evaluating the load recovery situation.The Floyd algorithm based dynamic traffic assignment(DTA)is selected to obtain the optimal path of the MESSs.In the third stage,the outputs of various post-disaster recovery measures are adjusted to achieve an economically optimized operation.Case studies demonstrate the effectiveness of the proposed dynamic post-disaster recovery strategy. 展开更多
关键词 dynamic post-disaster recovery dynamic transportation network integrated energy system resilience distribution
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Flow curve correction and processing map of 2050 Al-Li alloy 被引量:6
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作者 Rui-hua ZHU Qing LIU +3 位作者 Jin-feng LI Yong-lai CHEN Xu-hu ZHANG Zi-qiao ZHENG 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2018年第3期404-414,共11页
Hot compression tests of 2050 Al-Li alloy were performed in the deformation temperature range of 340-500°C and strain rate range of 0.001-10 s-1 to investigate the hot deformation behavior of the alloy.The effect... Hot compression tests of 2050 Al-Li alloy were performed in the deformation temperature range of 340-500°C and strain rate range of 0.001-10 s-1 to investigate the hot deformation behavior of the alloy.The effects of friction and temperature difference on flow stress were analyzed and the flow curves were corrected.Based on the dynamic material model,processing map at a strain of 0.5 was established.The grain structure of the compressed samples was observed using optical microscopy.The results show that friction and temperature variation during the hot compression have significant influences on flow stress.The optimum processing domains are in the temperature range from 370 to 430°C with the strain rate range from 0.01 to 0.001 s-1,and in the temperature range from 440 to 500°C with the strain rate range from 0.3 to 0.01 s-1;the flow instable region is located at high strain rates(3-10 s-1)in the entire temperature range.Dynamic recovery(DRV)and dynamic recrystallization(DRX)are the main deformation mechanisms of the 2050 alloy in the stable domains,whereas the alloy exhibits flow localization in the instable region. 展开更多
关键词 2050 Al-Li alloy processing map dynamic recovery dynamic recrystallization flow localization
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Microstructure evolution of Al-Zn-Mg-Cu-Zr alloy during hot deformation 被引量:4
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作者 YAN Liangming,SHEN Jian,LI Zhoubing,LI Junpeng,and YAN Xiaodong General Research Institute for Nonferrous Metals,Beijing 100088,China 《Rare Metals》 SCIE EI CAS CSCD 2010年第4期426-432,共7页
Compression tests of the Al-Zn-Mg-Cu-Zr(7055) alloy were performed at various strains and temperatures from 300 to 450℃ under a con- stant strain rate between 10^-2 s^-1and 1 s^-1. Microstructures during hot deform... Compression tests of the Al-Zn-Mg-Cu-Zr(7055) alloy were performed at various strains and temperatures from 300 to 450℃ under a con- stant strain rate between 10^-2 s^-1and 1 s^-1. Microstructures during hot deformation were studied by transmission electron microscopy (TEM). Dislocation density, dislocation cells and subgrains of the deformed samples were investigated in detail and compared to make a better understanding of the microstructure evolution. The results showed that stress-strain curves under the experimental conditions belonged to the type of dynamic recovery. When the alloy deformed at various strains and 300℃, the microstructure underwent a process of disordered dislocations to cell structure, subgrain structure and subgrain coarsening. With the temperature increasing, subgrains grew and dislocation density in the interior decreased at a strain rate of 1 s^-1. At the temperature of 350℃, the average diameter of subgrains decreased, sub-boundaries broadened and dislocation density in the interior decreased when the strain rate was increased. The deformed samples of 7055 alloy had smaller subgrains than that of 7005 alloy at the same compression condition because of high alloy content. 展开更多
关键词 aluminum alloy microstructure evolution dynamic recovery SUBGRAIN
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Deformation behavior of explosive detonation in electroformed nickel liner of shaped charge with nano-sized grains 被引量:3
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作者 杨峰 李春华 +2 位作者 成生伟 王雷 田文怀 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2010年第8期1397-1402,共6页
Nickel liner of shaped charge with nano-sized grains was prepared by electroforming technique and the ultra-highstrain-rate deformation was performed by explosive detonation.The as-electroformed and post-deformed micr... Nickel liner of shaped charge with nano-sized grains was prepared by electroforming technique and the ultra-highstrain-rate deformation was performed by explosive detonation.The as-electroformed and post-deformed microstructures of electroformed nickel liner of shaped charge were observed by optical metallography(OM),scanning electron microscopy(SEM) and transmission electron microscopy(TEM) and the orientation distribution of the grains was analyzed by electron backscattering pattern(EBSP) technique.Both melting phenomenon in the jet fragment and recovery and recrystallization in the slug after ultra-high-strain-rate deformation were observed.The research evidence shows that dynamic recovery and recrystallization play an important role in ultra-high-strain-rate deformation for electroformed nickel liner of shaped charge with nano-sized grain. 展开更多
关键词 nano-sized electroformed nickel ultra-high-strain-rate deformation ELECTROFORMATION MICROTEXTURE dynamic recovery and recrystallization DETONATION
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Constitutive model for a new kind of metastable β titanium alloy during hot deformation 被引量:3
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作者 王哲君 强洪夫 +1 位作者 王学仁 王广 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2012年第3期634-641,共8页
The constitutive model was developed to describe the relationship among flow stress,strain,strain rate,and deformation temperature completely,based on the characteristics of flow stress curves for a new kind of metast... The constitutive model was developed to describe the relationship among flow stress,strain,strain rate,and deformation temperature completely,based on the characteristics of flow stress curves for a new kind of metastable β Ti2448 titanium alloy from isothermal hot compression tests,in a wide range of temperatures(1023-1123 K) and strain rates(63-0.001 s-1).During this process,the adopted hyperbolic sine function based on the unified viscoplasticity theory was used to model the flow behavior of alloy undergoing flow softening caused by dynamic recovery(DRV) at high strain rates(≥1 s-1).The standard Avrami equation was adopted to represent the softening mechanism attributed to dynamic recrystallization(DRX) at low strain rates(1 s-1).Additionally,the material constants were determined by optimization strategy,which is a new method to solve the nonlinear constitutive equation.The stress—strain curves predicted by the developed constitutive model agree well with the experimental results,which con-rms that the developed constitutive model can give an accurate estimate of the-ow stress of Ti2448 titanium alloy and provide an effective method to model the flow behavior of metastable β titanium alloys during hot deformation. 展开更多
关键词 metastable β titanium alloy hot compression dynamic recovery dynamic recrystallization constitutive model
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Influence of welding speed on microstructure formation in friction-stir-welded 304 austenitic stainless steels 被引量:3
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作者 Mohsen Hajizadeh Sajjad Emami Tohid Saeid 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2020年第11期1517-1524,共8页
The influence of welding speed on the joint microstructures of an austenitic stainless steel(ASS)produced by friction stir welding(FSW)was investigated.The FSW process was conducted using a rotational speed of 400 r/m... The influence of welding speed on the joint microstructures of an austenitic stainless steel(ASS)produced by friction stir welding(FSW)was investigated.The FSW process was conducted using a rotational speed of 400 r/min and welding speeds of 50 and 150 mm/min.The study was carried out using electron backscattered diffraction(EBSD)technique in different regions of the resultant stir zones(SZs).The results show that the texture of the advancing side(AS)was mainly composed of C{001}〈110〉and cube{001}〈100〉texture components along with partial B/B{112}〈110〉component.Moving from the AS toward the center and the retreating side(RS),the cube texture component disappeared and the A;/A*{111}(112)component developed and predominated the other components.Higher welding speed greatly affected and decreased the intensity of the textures in the resultant SZs.Moreover,higher welding speed(lower heat input)resulted in lower frequency of cube texture in the AS. 展开更多
关键词 friction stir welding stainless steels welding speed dynamic recovery shear texture continuous dynamic recrystallization
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Hot deformation behavior of FGH96 superalloys 被引量:4
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作者 Jiantao Liu Guoquan Liu +3 位作者 Benfu Hu Yuepeng Song Ziran Qin Yiwen Zhang 《Journal of University of Science and Technology Beijing》 CSCD 2006年第4期319-323,共5页
The hot deformation behavior of FGH96 superalloys at 1070-1170℃ and 5×10^-4-2×10^-1 s^-1 were investigated by means of the isothermal compression tests at a Gleeble-1500 thermal mechanical simulator. The re... The hot deformation behavior of FGH96 superalloys at 1070-1170℃ and 5×10^-4-2×10^-1 s^-1 were investigated by means of the isothermal compression tests at a Gleeble-1500 thermal mechanical simulator. The results show that dynamic recovery acts as the main softening mechanism below 2×10^-3 s^-1, whereas dynamic recrystallization acts as the main softening mechanism above 2× 10^-3 s^-1 during deformation; the temperature increase caused by the deformation and the corresponding softening stress is negligible; the thermal-mechanical constitutive model to describe the hot deformation behavior is given, and the value of the apparent deformation activation energy (Qdef) is determined to be 354.93 kJ/mol. 展开更多
关键词 FGH96 superalloys hot deformation hot deformation activation energy dynamic recovery dynamic recrystallization
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