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Fine Grained Feature Extraction Model of Riot-related Images Based on YOLOv5
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作者 Shaofan Su Deyu Yuan +1 位作者 Yuanxin Wang Meng Ding 《Computer Systems Science & Engineering》 SCIE EI 2023年第4期85-97,共13页
With the rapid development of Internet technology,the type of information in the Internet is extremely complex,and a large number of riot contents containing bloody,violent and riotous components have appeared.These c... With the rapid development of Internet technology,the type of information in the Internet is extremely complex,and a large number of riot contents containing bloody,violent and riotous components have appeared.These contents pose a great threat to the network ecology and national security.As a result,the importance of monitoring riotous Internet activity cannot be overstated.Convolutional Neural Network(CNN-based)target detection algorithm has great potential in identifying rioters,so this paper focused on the use of improved backbone and optimization function of You Only Look Once v5(YOLOv5),and further optimization of hyperparameters using genetic algorithm to achieve fine-grained recognition of riot image content.First,the fine-grained features of riot-related images were identified,and then the dataset was constructed by manual annotation.Second,the training and testing work was carried out on the constructed dedicated dataset by supervised deep learning training.The research results have shown that the improved YOLOv5 network significantly improved the fine-grained feature extraction capability of riot-related images compared with the original YOLOv5 network structure,and the mean average precision(mAP)value was improved to 0.6128.Thus,it provided strong support for combating riot-related organizations and maintaining the online ecological environment. 展开更多
关键词 Convolutional neural network YOLOv5 riot-related fine grained target detection
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Breeding and Application of Japonica CMS Line Yangfujing 7A with Fine Grain Quality, Disease Resistance and High Combining Ability in Rice
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作者 周根友 夏华 《Agricultural Science & Technology》 CAS 2017年第2期377-379,共3页
Yangfujing 7A, derived from the cross between Xu 9201A and Yangfujing 7 and its successive backcrosses, is a BT-type japonica CMS line developed by the Agricultural Institute of Riparian Region of Jiangsu Province. It... Yangfujing 7A, derived from the cross between Xu 9201A and Yangfujing 7 and its successive backcrosses, is a BT-type japonica CMS line developed by the Agricultural Institute of Riparian Region of Jiangsu Province. It shows good integrat- ed characteristics, stable male sterility, good flowering habits, high out crossing rate, strong disease resistance, fine grain quality (reaching the 1st class of national standards for fine quality rice) and high combining ability. In 2012, it was technically identified in Jiangsu Province. Its F1 hybrid combination Tongyoujingl (Yangfujing 7 A/R98), showing high yield and good grain quality, was registered and released to commercial production by Jiangsu Crop Variety Appraisal Committee in 2013. 展开更多
关键词 Japonica hybrid rice CMS line Yangfujing 7A fine grain quality Dis- ease resistance BREEDING
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Microstructures of ultra-fine grained FeCoV alloys processed by ECAP plus cold rolling and their evolutions during tempering 被引量:5
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作者 伍来智 陈军 +1 位作者 杜忠泽 王经涛 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2010年第4期602-606,共5页
A new processing method,equal channel angular pressing(ECAP)plus cold rolling(CR),was applied to producing ultra-fine grained FeCoV alloy.The microstructures of ultra-fine grained FeCoV alloy after ECAP,ECAP plus CR,a... A new processing method,equal channel angular pressing(ECAP)plus cold rolling(CR),was applied to producing ultra-fine grained FeCoV alloy.The microstructures of ultra-fine grained FeCoV alloy after ECAP,ECAP plus CR,and the effect of tempering treatment on the microstructure of FeCoV alloy produced by ECAP plus CR were investigated.The results show that an elongated substructure with a width of about 0.3μm is obtained after four-pass ECAP using Route A.Cold rolling after ECAP cannot change the morphologies of elongated substructure,and it results in higher fraction of high-angle boundaries and higher dislocation density compared with the identical ECAP without rolling.Subsequent tempering for 30 min at 853 K brings about many nano-phases precipitating at subgrain boundaries and insides the grains,and the size of precipitated phase is measured to be about 10 nm.Nano-phases grow up with increasing tempering temperature and equiaxed structure forms at 883 K. 展开更多
关键词 FeCoV alloy equal channel angular pressing cold rolling ultra-fine grain
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THE WEAR PERFORMANCES OF FINE GRAINED ALUMINA BALLS 被引量:1
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作者 秦麟卿 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2000年第4期66-70,共5页
The wear performance of fine grain alumina ball adding diopside as fluxing agent are reported for the first time in this paper. The ball (average grain size 3 mum) exhibits excellent toughness and low wear rates. Plou... The wear performance of fine grain alumina ball adding diopside as fluxing agent are reported for the first time in this paper. The ball (average grain size 3 mum) exhibits excellent toughness and low wear rates. Ploughing grooves and traces of micro-cutting occur at the place with no pore. And the wear process is mainly caused by plastic deformation mechanism. Yet, the ordinary alumina balls (average grain size 6 and 15 mum) are brittle and the wear rates are high. The intergranular and transgranular dropping pits occur, and the wear process in mainly caused by brittle fracture mechanism. 展开更多
关键词 DIOPSIDE alumina ball fine grain plastic deformation WEAR
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Effect of welding heat input on HAZ character in ultra-fine grain steel welding 被引量:3
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作者 张富巨 许卫刚 +3 位作者 王玉涛 王燕 张学刚 廖永平 《China Welding》 EI CAS 2003年第2期122-127,共6页
In this essay, we studied how heat input affected the microstructure, hardness, grain size and heat-affected zone(HAZ) dimension of WCX355 ultra-fine grain steel which was welded respectively by the ultra narrow-gap w... In this essay, we studied how heat input affected the microstructure, hardness, grain size and heat-affected zone(HAZ) dimension of WCX355 ultra-fine grain steel which was welded respectively by the ultra narrow-gap welding (UNGW) process and the overlaying process with CO 2 as protective atmosphere and laser welding process. The experimental results show when the heat input changed from 1.65 kJ/cm to 5.93 kJ/cm, the width of its HAZ ranged from 0.6 mm to 2.1 mm.The average grain size grew up from 2~5 μm of base metal to 20~70 μm and found no obvious soften phenomenon in overheated zone. The width of normalized zone was generally wide as 2/3 as that of the whole HAZ, and the grain size in this zone is smaller than that in base metal. Under the circumstance of equal heat input, the HAZ width of UNGW is narrower than that of the laser welding. 展开更多
关键词 heat input heat-affected zone ultra-fine grain steel ultra narrow-gap welding
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Microstructural Evolution and Thermal Stability of Ultra-fine Grained Al-4Mg Alloy by Equal Channel Angular Pressing 被引量:1
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作者 HongbinGENG SubbongKANG ShiyuHE 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2004年第3期315-318,共4页
Experiments were conducted to evaluate the grain refinement and thermal stability of ultra-fine grained Al-4Mgalloy introduced by equal-channel angular pressing (ECAP) at 473 K. The results show that the intensities o... Experiments were conducted to evaluate the grain refinement and thermal stability of ultra-fine grained Al-4Mgalloy introduced by equal-channel angular pressing (ECAP) at 473 K. The results show that the intensities of X-ray(111/222) and (200/400) peaks for the alloy processed by ECAP decrease significantly and the peak widths of halfheight become broadening compared with the corresponding value in the annealed alloy. The microstructure of 2passes ECAPed alloy consists of both elongated and equiaxed subgrains. The residual strain in the alloy increaseswith increasing passes numbers, that appears as increasing dislocation density and lattice constant of matrix. Anequiaxed ultra-fine grained structure of~0.2μm is obtained in the present alloy after 8 passes. The ultra-fine grainsare stable below 523 K, because the alloy retains extremely fine grain size of~1μm after static annealing at 523 Kfor 1 h. 展开更多
关键词 Aluminum alloy Equal channel angular pressing Ultra-fine grain Microstructural stability
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Three Dimension Monte Carlo Simulation of Austenite Grain Growth in CGHAZ of an Ultrafine Grain Steel 被引量:1
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作者 DongCHEN YongpingLEI +2 位作者 XiaoyanLI YaowuSHI ZhilingTIAN 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2003年第4期309-312,共4页
In the present research Monte Carlo technique was used to simulate the grain growth in heat-affected zone(HAZ) of an ultrafine grain steel. An experimental data based (EBD) model proposed by Gao was used to establish ... In the present research Monte Carlo technique was used to simulate the grain growth in heat-affected zone(HAZ) of an ultrafine grain steel. An experimental data based (EBD) model proposed by Gao was used to establish the relation between tMCS and real time temperature kinetics in our simulation. The simulations give out the evolution of grain structure and grain size distribution in HAZ of the ultrafine grain steel. A Microsoft Window based on computer program for the simulation of grain growth in the HAZ of weldment in three dimensions has been developed using Monte Carlo technique. For the system, inputting the temperature field data and material properties, the evolution of grain structure, both image of simulated grain structure and numerical datum reflecting grain size distribution can be produced by the program. The system was applied to the ultrafine grain steel welding, and the simulated results show that the ultrafine grain steel has large tendency of grain growth. 展开更多
关键词 Ultra-fine grain steel HAZ Monte Carlo simulation
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Effect of upsetting force on microstructure of welds in resistance spot welding of 400 MPa ultra-fine grain steel 被引量:1
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作者 Deng Lipeng Ke Liming +1 位作者 Liu Jinhe Ji Chuntao 《China Welding》 EI CAS 2016年第2期76-82,共7页
The ultra-fine grain (UFG) steel is welded by using resistance spot welding technique with or without requirement of upsetting force. Metallographic inspection shows that the grain size of weld nugget is larger than... The ultra-fine grain (UFG) steel is welded by using resistance spot welding technique with or without requirement of upsetting force. Metallographic inspection shows that the grain size of weld nugget is larger than that of the base metal and the microstructure is altered significantly. In addition, contracting defects such as air holes can be found in the nugget center. The experiments show that the defects can be effectively avoided by the technique of adding upsetting force during the nugget cooling and crystallizing processes. In tensile shear tests, the welding joint starts to crack from the inner edge of the corona bond. The results of micro-hardness tests show that the newly born martensite structure dramatically improves the hardness of the joint. Under the interactions between residual stresses and regenerated fine grains, the micro-hardness of the heat-affected zone ( HAZ ) is lower than that of the nugget, but evidently higher than that of the base metal. 展开更多
关键词 ultra-fine grain steel resistance spot welding MICROSTRUCTURE mechanical property
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Microstructure and Mechanical Properties of Ultrafine Grained Mg15Al Alloy Processed by Equal-channel Angular Pressing 被引量:1
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作者 王红霞 梁伟 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2010年第2期238-242,共5页
An as-cast magnesium alloy with high Al content Mg15Al was subjected to equal-channel angular pressing (ECAP) through a die with an angle of φ= 90? at 553 K following route Bc. It is found that the network β-Mg17... An as-cast magnesium alloy with high Al content Mg15Al was subjected to equal-channel angular pressing (ECAP) through a die with an angle of φ= 90? at 553 K following route Bc. It is found that the network β-Mg17Al12 phases in the as-cast Mg15Al alloy are broken into small blocks and dispersed uniformly with increasing numbers of pressing passes. Moreover, many nano-sized Mg17Al12 particles precipitate in the ultra-fine α-Mg matrix. The grains are obviously refined. However, the grain structure is inhomogeneous in different areas of the alloy. The average size of the primary phase α-Mg is reduced to about 1 μm while grains of around 0.1-0.2 μm are obtained in some two-phase areas. With additional ECAP passes (up to 8), coarsening of the grains occurs by dynamic recovery. Room temperature tensile tests show that the mechanical properties of Mg15Al alloys are markedly improved after 4 ECAP passes. The ultimate tensile strength and elongation to failure increase from 150 MPa to 269.3 MPa and from 0.05% to 7.4%, respectively. Compared with that after 4 passes, the elongation to failure of the alloy increases but the strength of the alloy slightly decreases after 8 ECAP passes. Fracture morphology of the ECAP-processed alloy exhibits dimple-like fracture characteristics while the as-cast alloy shows quasi-cleavage fractures. 展开更多
关键词 high-aluminum Mg Alloy β-Mg17Al12 phase ultra-fine grained microstructure mechanical properties equal-channel angular pressing
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INVESTIGATION ON FRACTURE BEHAVIOR FOR WELDED JOINT OF NEW GENERATION FINE GRAINED STEEL SS400
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作者 H.Y.Jing X.G.Liu +2 位作者 Z.Q.Zhu L.X.Huo Y.F.Zhang 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2003年第1期35-40,共6页
The fracture behavior for welded joint of new generation fine grained steel SS400 was investigated and assessed on the basis of fitness for purpose philosophy. The actual critical defect sizes for the SS400 base metal... The fracture behavior for welded joint of new generation fine grained steel SS400 was investigated and assessed on the basis of fitness for purpose philosophy. The actual critical defect sizes for the SS400 base metal and its weld HAZ (heat affected zone) defined by the gross yielding criterium have been determined directly by means of wide plate tests. It has been shown that although the HAZ grain growth occurs due to the welding heat, the resistance to fracture is not deteriorated. The deformation behavior of wide plate specimen was also studied by finite, element (FE) analysis. The deformation of weld HAZ is protected by the high strength weld metal, so it is easier to get the general yielding for the welded joint specimen. 展开更多
关键词 fine grained steel general yielding wide plate test fracture behavior
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Prediction of HAZ grain size in welding of ultra fine grained steel with different parameters
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作者 赵洪运 张洪涛 +1 位作者 李冬青 王国栋 《China Welding》 EI CAS 2010年第4期63-67,共5页
The temperature field and thermal cycling curve in the heat-affected zone during welding 400 MPa ultra fine grained steel by plasma arc were simulated using finite element method. The principle of grain growth kinetic... The temperature field and thermal cycling curve in the heat-affected zone during welding 400 MPa ultra fine grained steel by plasma arc were simulated using finite element method. The principle of grain growth kinetics was used to predict the grain size in the heat-affected zone under different welding parameters. The simulation results show that the growing tendency of HAZ grain could be controlled by adjusting the welding parameters, but the growth of HAZ grain could not be eliminated at all. The HAZ grain size became small with increasing of the cooling rate and added with increasing of welding current, arc voltage and welding speed. 展开更多
关键词 ultra fine grained steel thermal cycling curve welding heat-affected zone grain size
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Study on improving properties of welded joints of 400 MPa ultra fine grained steel by mechanical surface hardening
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作者 赵洪运 韩飞 +1 位作者 夏龙 刘雪云 《China Welding》 EI CAS 2006年第1期34-38,共5页
The welded joints of 400 MPa ultra fine grained steel in manual arc welding were treated by mechanical surface hardening. Microstructure and mechanical properties of the treated joints were compared with those of the ... The welded joints of 400 MPa ultra fine grained steel in manual arc welding were treated by mechanical surface hardening. Microstructure and mechanical properties of the treated joints were compared with those of the untreated joints, based on which, primary study on the process and principle of mechanical surface hardening was carried out. The results shows that: Grain size of HAZ increases greatly and mechanical properties of welded joint decrease obviously compared with those of base martial, but grain size in the surface layer of HAZ can be refined (the grain size is about 100 nm or so) and mechanical properties of welded joints can be improved greatly by mechanical surface hardening. 展开更多
关键词 mechanical surface hardening welded joint ultra fine grained steel
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Investigation of Microstructure of Fine Grain Cast IN718 Compressor Blade from Abroad
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作者 MA Yue HU Yaohe XIE Xishan (Material Science and Engineering School, USTB,Beijing 100083, China) 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 1997年第2期50-50,共1页
Fine grain cast IN718 compressor blade form abroad has been analyzed. There is no columnar grain, uniform equiaxed grain, less segregation and no porosity cast defect in essence in the section of blade body with fine ... Fine grain cast IN718 compressor blade form abroad has been analyzed. There is no columnar grain, uniform equiaxed grain, less segregation and no porosity cast defect in essence in the section of blade body with fine grain, in which grain size is about ASTM 2 ~4. Its microstructure is approachable to that of forging. It is hopeful to achieve the goal of replacing forging by casting. 展开更多
关键词 fine grain cast compressor blade microstructure
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Surface Cracking Behaviors of Ultra-Fine Grained Tungsten Under Edge Plasma Loading in the HT-7 Tokamak
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作者 朱大焕 刘洋 +2 位作者 陈俊凌 周张健 鄢容 《Plasma Science and Technology》 SCIE EI CAS CSCD 2013年第6期605-608,共4页
Tests of the candidate plasma facing materials(PFMs) used in experimental fusion devices are essential due to the direct influence of in-situ plasma loading.A type of ultrafine grained(UFG) tungsten sintered by re... Tests of the candidate plasma facing materials(PFMs) used in experimental fusion devices are essential due to the direct influence of in-situ plasma loading.A type of ultrafine grained(UFG) tungsten sintered by resistance sintering under ultra-high pressure(RSUHP) method has been exposed in the edge plasma of the HT-7 tokamak to investigate its performance under plasma loading.Under cychc edge plasma loading,the UFG tungsten develops both macro and micro cracks.The macro cracks are attributed to the low temperature brittleness of the tungsten material itself,while the micro cracks are generated from local intense power flux deposition. 展开更多
关键词 ultra-fine grain tungsten plasma facing materials cracking behaviors plasma irradiation
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Investigation on fracture behavior of the welded joint HAZ of ultra-fine grain steel SS400
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作者 朱政强 陈立功 +3 位作者 荆洪阳 葛景国 倪纯珍 饶德林 《China Welding》 EI CAS 2003年第2期142-145,共4页
The critical crack dimensions of both base-metal specimen and HAZ specimen are measured via wide-plate tensile tests. Based on the “fitness for purpose” principle, the fracture behavior of the ultra-fine grain steel... The critical crack dimensions of both base-metal specimen and HAZ specimen are measured via wide-plate tensile tests. Based on the “fitness for purpose” principle, the fracture behavior of the ultra-fine grain steel SS400 welded joint HAZ is assessed. The test results indicate that overmatching is benefit for the whole capability’s improvement of ultra-fine grain steel SS400. The test results are confirmed by using finite element method (FEM). 展开更多
关键词 ultra-fine grain steel fitness for purpose general yielding FEM
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Corrosion behavior of ultra-fine grained industrial pure Al fabricated by ECAP 被引量:9
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作者 宋丹 马爱斌 +2 位作者 江静华 林萍华 杨东辉 《中国有色金属学会会刊:英文版》 EI CSCD 2009年第5期1065-1070,共6页
Corrosion behavior of ultra-fine grained(UFG) industrial Al fabricated by equal channel angular pressing(ECAP) for 16 pass times was investigated by potentiodynamic polarization test,potentiostatic polarization test,e... Corrosion behavior of ultra-fine grained(UFG) industrial Al fabricated by equal channel angular pressing(ECAP) for 16 pass times was investigated by potentiodynamic polarization test,potentiostatic polarization test,electrochemical impedance spectroscopy(EIS) measurement,immersion test and surface analyses (OM and SEM). The microstructures including grain size,grain boundaries and dislocations were also observed by TEM. The results show that the UFG industrial pure Al has more positive pitting potential,less corrosion current density and five times larger passive film resistance compared with the coarse grained(CG) one. It was found that the increased pitting resistance is profited from the more stable passive film kept in the Cl-aggressive solution due to more grain boundaries,larger fraction of non-equilibrium grain boundaries and residual stress of the UFG industrial pure Al. 展开更多
关键词 超细晶粒 等径角挤压 工业纯铝 腐蚀行为 制备 电化学阻抗谱 透射电镜观察 腐蚀电流密度
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The Weathering Effects of Acidithiobacillus Ferrooxidans to Cu(Ⅱ) Pollution of Fine Grained Copper Mine Tailings
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作者 LI Dou SONG Liyan 《矿物学报》 CAS CSCD 北大核心 2013年第S1期43-43,共1页
China has accumulated massive fine grained copper mine tailings stocks because of the past mining activities in this area. The tailings contain a variety of heavy metals, and the mass percent of Cu, which is one of th... China has accumulated massive fine grained copper mine tailings stocks because of the past mining activities in this area. The tailings contain a variety of heavy metals, and the mass percent of Cu, which is one of the main contaminants in tailings, is up to 0.2601% (analysis by XRF). The Cu can pollute soil and groundwater by rain leaching in the form of Cu(Ⅱ), furthermore ,the fine grained copper-ore-tailings can contaminant larger area by wind for its small granularity ( < 74 μm). The main cause of weathering of mine tailings is due to oxidative dissolution of sulfides. Microorganisms, such as Acidithiobacillus ferrooxidans, play an important role in weathering. These bacteria attach to exposed to mineral surfaces by excreting extracellular polymers and oxidize the sulfide mineral. Some of these bacteria also oxidize Fe2+ to Fe3+ which can chemically oxidize sulfide minerals. These reactions produce voluminous quantities of acid mine drainage and heavy metals which are harmful to the environment and human healthy. This study aims at finding the weathering effects of A. ferrooxidans to Cu(II) pollution of fine grained copper mine tailings, and our experiment applied indigenous A. ferrooxidans FJ-01 to leach the tailings. The optimum test parameters were obtained using shaking flask experiment and SEM observation under the following experimental conditions: 39 days residence time, pulp density 1%-15% (1%, 5% and 15%), 30℃, 120 rpm, pH between 1-3 and redox potential between 400-650 mV. The test results show that the leaching rate of Cu reached 43.1% when the pulp density was 1% after 33 days and kept invariant till the end of the test. In addition, the leaching rate of Cu will decrease as the increase of pulp density, and the maximum rate of 15% pulp density was only 12.5%. From the SEM, it can be seen that the fine grain of tailings flocculated to conglobation under the action of bacterial leaching. 展开更多
关键词 WEATHERING EFFECTS fine grained copper-ore-tailings Cu(Ⅱ ) POLLUTION ACIDITHIOBACILLUS ferrooxidans
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High-temperature creep properties of fine grained heat-affected zone in P92 weldment
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作者 王学 史专 +1 位作者 潘乾刚 吴洪亮 《中国有色金属学会会刊:英文版》 CSCD 2009年第S3期772-775,共4页
The simulated fine grained heat-affected zone (FGHAZ) specimens for P92 welded joints were prepared by heat treatment, then the creep tests were carried out at 650 ℃ under the applied stress of 90-120 MPa to investig... The simulated fine grained heat-affected zone (FGHAZ) specimens for P92 welded joints were prepared by heat treatment, then the creep tests were carried out at 650 ℃ under the applied stress of 90-120 MPa to investigate high-temperature creep behavior of FGHAZ. The results show that the creep property of FGHAZ is much inferior to that of the base metal, which exhibits the much higher steady creep rate and shorter time to creep fracture. The power law equation can describe the steady creep rate dependence on applied stress, indicating that the stress exponent n of FGHAZ is distinguished between two regions with n=15.1 at high stresses (more than 100 MPa) and n=8.64 at lower stresses. Based on Monkman-Grant equation, the relationship between the secondary creep rate and time to rupture is obtained to evaluate the creep life of FGHAZ with the applied stress above 100 MPa. 展开更多
关键词 RESISTANT heat steel welding fine grained heat-affected zone(FGHAZ) CREEP
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Groove Design and Microstructure Research of Ultra-Fine Grain Bar Rolling
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作者 Xuetong Li Lei Cao +1 位作者 Minting Wang Fengshan Du 《Modeling and Numerical Simulation of Material Science》 2012年第4期67-75,共9页
New flat-oval groove rolling process of multi-direction deformation is proposed to manufacture ultra-fine grain bar. Application of new groove series can introduce uniform large plastic strain into whole cross section... New flat-oval groove rolling process of multi-direction deformation is proposed to manufacture ultra-fine grain bar. Application of new groove series can introduce uniform large plastic strain into whole cross section of the material, and meanwhile satisfy the requirements of shape and size. Principle of grain refinement, based on experimental research of small specimen, is that grain refinement of ferrite is mainly dynamic recrystallization when low-carbon alloy steel is at low temperature deformation. Relationship of grain size and z-factor is also obtained through experimental research, as well as ultra-fine ferrite grain less than 1 micron. To predict strain, shape, dimensions and grain size of the material in rolling process, numerical simulation model of the warm groove bar rolling process is established via nonlinear finite element method, and distribution of grain size of the final section is obtained via finite element subroutine. The result indicates that ultra-fine grain bar rolling can accomplish at low temperature region. 展开更多
关键词 BAR FEM Flat-Oval GROOVE Large PLASTIC Strain Low Temperature Ultra-fine grain
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Microstructures and mechanical properties of laser welded wrought fine-grained ZK60 magnesium alloy 被引量:1
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作者 严红革 赵嫱 +2 位作者 陈瓶 陈吉华 苏斌 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2015年第2期389-396,共8页
Fine-grained ZK60 magnesium alloy sheets of 2.0 mm in thickness were successfully joined by laser beam welding (LBW). The effects of welding parameters including laser power and welding speed on the microstructures ... Fine-grained ZK60 magnesium alloy sheets of 2.0 mm in thickness were successfully joined by laser beam welding (LBW). The effects of welding parameters including laser power and welding speed on the microstructures and mechanical properties of the joints were investigated. A sound bead, with the ultimate tensile strength (UTS) of 300 MPa and elongation of 12.0%, up to 92.5% and 65% of those of the base metal, respectively, is obtained with the optimized welding parameters. No liquation cracking is visible in the partially melted zone (PMZ) owing to the inhibitory action of the fine dispersed precipitates and the fine-grained microstructure in the as-rolled magnesium alloy sheets. The fusion zone (FZ) is featured with the equiaxed dendritic grains of the average grain size about 8 μm, which are similar to those in the heat affected zone (HAZ), and this contributes to the relatively high joint efficiency. 展开更多
关键词 ZK60 magnesium alloy fine grain size laser beam welding heat affected zone partially melted zone
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