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BEHAVIOR Of SHORT fATIGUE CRACKS AT BLUNT NOTCHES IN A MEDIUM CARBON STEEL

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Acta Metallurgica Sinica(English Letters) 1997年第5期10卷 430-436页

作者： Wu, Z.x. Sun, x.f. Southwest Jiaotong Univ Chengdu China

The behavior of part-through and through short cracks in single edge blunt notched specimens of a medium carbon steel was investigated by a replication method. It is found that the fatigue failure of these notched specimens is caused mainly by the growth of short surface cracks originating from the surface of notch root. More than 70% of the fatigue life is spent in the regimes in which short surface cracks initiate and propagate as part-through cracks before joining up to form a single through-thickness crack. The effect of original crack profile which is formed through the coalescence of multiple part-through cracks is the main reason causing the 'anomalous' propagation behavior of the through-thickness crack in its early stage.

关键词： Carbon steel Crack initiation Crack propagation fatigue of materials fracture mechanics Surfaces

Merging bound states in the continuum in an open acoustic resonator

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Science China(Physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 124-131页

作者： Lujun Huang Bin Jia Artem S.Pilipchuk Sibo Huang chen Shen Almas f.Sadreev Yong Li Andrey E.Miroshnichenko School of Physics and Electronic Sciences East China Normal University Institute of Acoustics Tongji University L.V.Kirensky Institute of Physics Department of Mechanical Engineering Rowan University School of Engineering and Technology University of New South Wales at Canberra

Bound states in the continuum （BICs） are perfectly localized resonances despite embedding in the continuum ***,an isolated BIC is very sensitive to the structure ***,we report merging acoustic BICs in a single open resonator,robust against the structure *** find that both symmetry-protected BIC and friedrich-Wintgen BIC are sustained in a single coupled waveguide-resonator *** varying the height and length of the resonator,these two BICs move toward each other and merge into a single one at a critical *** to an individual BIC,the merged BIC is robust against fabrication error because its Q-factor is proportional to ΔL-4,whereΔL embodies the structure *** essence of this extraordinary phenomenon is perfectly explained by the two-and three-level approximations of the effective nonHermitian ***,we present direct experimental demonstrations of the moving and merging of BICs in a coupled 3D waveguide-resonator,which are evidenced by the vanishing of the linewidth of fano resonance in the transmission *** results may find exciting applications in designing high-quality acoustic sources,sensors and filters.

关键词： acoustic resonances bound state in the continuum high-Q resonances

MICROSTRUCTURES AND PROPERTIES Of RECIPROCATINGLY ExTRUDED Mg-6.4Zn-1.1Y ALLOYS

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Acta Metallurgica Sinica(English Letters) 2008年第1期21卷 37-42页

作者： Z.M. Zhang C.J. xu x.f. Guo School of Materials Science ＆ Engineering Xi＇an University of Technology Xi＇an 710048 China

An icosahedral Mg3 YZn6 quasicrystalline phase can be produced in Mg-Zn- Y system alloys when a proper amount of Zn and Y is contained, and it is feasible to prepare the quasicrystal phase-reinforced low-density magnesium alloy. In this article, phase constituents and the effect of reciprocating extrusion on microstructures and properties of the as-cast Mg-6.4Zn-1.1 Y alloy are analyzed. The microstructure of the as-cast Mg-6.4Zn-1.1 Y alloy consists of the α-Mg solid solution, icosahedral Mg3YZn6 quasicrystal, and Mg3 Y2Zn3 and MgZn2 compounds. After the alloy was reciprocatingly extruded for four passes, grains were refined, Mg3 Y2 Zn3 and MgZn2 phases dissolved into the matrix, whereas, Mg3 YZn6 precipitated and distributed uniformly. The alloy possesses the best performance at this state; the tensile strength, yield strength, and elongation are 323.4 MPa, 258.2 MPa, and 19.7%, respectively. In comparison with that of the as-cast alloy, the tensile strength, yield strength, and elongation of the reciprocatingly extruded alloy increase by 258.3%, 397.5%, and 18 times, respectively. It is concluded that reciprocating extrusion can substantially improve the properties of the as-cast Mg-6.4Zn-1.1 Y alloy, particularly for elongation. The high performance of the Mg-6.4Zn-1.1 Y alloy after reciprocating extrusion can be attributed to dispersion strengthening and grain-refined microstructures.

关键词： Reciprocating extrusion Mg-Zn- Y alloy Icosahedral quasicrystal

MICROSTRUCTURE Of Mg-6.4Zn-1.1Y ALLOY fABRICATED BY RAPID SOLIDIfICATION AND RECIPROCATING ExTRUSION

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Acta Metallurgica Sinica(English Letters) 2008年第1期21卷 30-36页

作者： Z.M. Zhang C.J. xu x.f. Guo School of Materials Science ＆ Engineering Xi＇an University of Technology Xi＇an 710048 China

In order to explore the methods to prepare high-strength quasicrystal-reinforced magnesium alloys, the flakes of rapidly solidified Mg-6.4Zn-1.1 Y magnesium alloy with a thickness of 50-60μm were obtained by a melt spinning single-roller device, and the flakes were then processed into rods by reciprocating extrusion and direct extrusion. The microstructure of the alloy was analyzed by optical microscope and SEM, and the constituent phases were identified by xRD. Phase transformation and its onset temperature were determined by differential thermal analyzer （DTA）. The analysis result shows that rapid solidification for *** alloy can inhibit the eutectic reactions, broaden the solid solubility of Zn in α-Mg solute solution, and impede the formation of Mg3 Y2Zn3 and MgZn2 compounds, and thus help the icosahedral Mg3 YZn6 quasicrystal formed directly from the melt. The microstructure of the flakes consists of the α-Mg solid solution and icosahedral Mg3 YZn6 quasicrystal. Dense rods can be made from the flakes by two-pass reciprocating extrusion and direct extrusion. The interfaces between flakes in the rods can be welded and jointed perfectly. During the reciprocating extrusion and direct extrusion process, more Mg3 YZn6 compounds are precipitated and distributed uniformly, whereas the rods possess fine microstructures inherited from rapidly solidified flakes. The rods contain only two phases： α- magnesium solid solution as matrix and fine icosahedral Mg3 YZn6 quasicrystal which disperses uniformly in the matrix.

关键词： Magnesium alloy Rapid solidification Reciprocating extrusion Quasicrystal

A Lightweight Multiscale feature fusion Network for Solar Cell Defect Detection

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Computers, Materials & Continua 2025年第1期82卷 521-542页

作者： xiaoyun chen Lanyao Zhang xiaoling chen Yigang Cen Linna Zhang fugui Zhang School of Mechanical Engineering Guizhou UniversityGuiyang550025China School of Computer Science and Technology Beijing Jiaotong UniversityBeijing100044China

Solar cell defect detection is crucial for quality inspection in photovoltaic power generation *** the production process,defect samples occur infrequently and exhibit random shapes and sizes,which makes it challenging to collect defective ***,the complex surface background of polysilicon cell wafers complicates the accurate identification and localization of defective *** paper proposes a novel Lightweight Multiscale feature fusion network(LMff)to address these *** network comprises a feature extraction network,a multi-scale feature fusion module(Mff),and a segmentation ***,a feature extraction network is proposed to obtain multi-scale feature outputs,and a multi-scale feature fusion module(Mff)is used to fuse multi-scale feature information *** order to capture finer-grained multi-scale information from the fusion features,we propose a multi-scale attention module(MSA)in the segmentation network to enhance the network’s ability for small target ***,depthwise separable convolutions are introduced to construct depthwise separable residual blocks(DSR)to reduce the model’s parameter ***,to validate the proposed method’s defect segmentation and localization performance,we constructed three solar cell defect detection datasets:SolarCells,SolarCells-S,and *** and SolarCells-S are monocrystalline silicon datasets,and PVEL-S is a polycrystalline silicon *** results show that the IOU of our method on these three datasets can reach 68.5%,51.0%,and 92.7%,respectively,and the f1-Score can reach 81.3%,67.5%,and 96.2%,respectively,which surpasses other commonly usedmethods and verifies the effectiveness of our LMff network.

关键词： Defect segmentation multi-scale feature fusion multi-scale attention depthwise separable residual block

STRUCTURAL EVOLUTION Of UNDERCOOLED SINGLE-PHASE Ni-2wt%Pb MONOTECTIC ALLOY

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Acta Metallurgica Sinica(English Letters) 2001年第1期14卷 72-78页

作者： H.x. Zheng, H. xie and x.f. Guo (xi’an University of Technology, xi’an 710048, China) xi’an University of Technology

The structural evolution of undercooled single-phase Ni-2wt%Pb monotectic alloy was systematically investigated by the method of molten glass denucleating combined with superheating cycle. Within the achieved undercooling range of 22 to 280 K, the solidification structure undergoes three changes at 22 K, 88 K and 187 K, respectively. With the increase of undercooling, common dendrites, the first class granular grains, undercooled dendrites and the second class granular grains come out one after the other. Analytical results show that the granulation mechanism of the first class granular grains is owing to dendrite remelting and recrystallization, and the granulation mechanism of the second is owing to dendrite break-up and recrystallization.

关键词： Granulation Lead alloys Microstructure Structure (composition)

Measurements of γ/γ' Lattice Misfit and γ' Volume fraction for a Ru-containing Nickel-based Single Crystal Superalloy

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Journal of Materials Science & Technology 2011年第10期27卷 899-905页

作者： x.P. Tan J.L. Liu x P Song T. Jin x.f. Sun Z.Q. Hu Superalloy Division Institute of Metal Research Chinese Academy of Sciences- Shenyang 110016 China Analysis and Testing Division Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

A conventional x-ray diffractometer has been used to determine the -y/y＇ lattice misfit and γ＇ volume fraction for a Ru-containing nickel-based single crystal superalloy at room temperature. The rocking curve was used to characterize the distribution of subgrains. The diffraction peaks obtained by w-20 scan were used to determine the γ/γ＇ lattice misfit and γ＇ volume fraction. A three peaks fitting model was proposed. The peak fitting results are in good agreement with the model. The x-ray diffraction results indicate that the nickel-based single crystal superalloy was not a perfect monocrystalline material, which is comprised of many subgrains; and each subgrain also consists of large numbers of mosaic structures. In addition, two anomalous reflection phenomena were found during the experiment and discussed with respect to their occurrence and impact on the measurement. The experimental results show that the γ/γ＇ lattice misfit and ~/r volume fraction will be various at the different regions of its dendritic microstructure. The average γ/γ＇ lattice misfit and γ＇ volume fraction of the experimental alloy are approximately-0.2% and 70%, respectively. furthermore, the γ＇ volume fraction calculated by atom microprobe （AP） data is also basically consistent with the experimental results.

关键词： Nickel-based superalloy Microstructure x-ray diffraction Lattice misfit y' volume fraction

INVESTIGATION ON HOT DUCTILITY AND STRENGTH Of CONTINUOUS CASTING SLAB fOR AH32 STEEL

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Acta Metallurgica Sinica(English Letters) 2006年第1期19卷 75-78页

作者： G. Y. Li x.f. Li L.G. Ao Technology Center Anshan Iron and Steel Group CorporationAnshan 114009 China

By means of Gleeble-1500 testing machine, the simulation of continuous casting process forAH32 steel was carried out and hot ductility and strength were determined. The cracking sensitivity was studied under the different temperatures and strain rates. The Precipitations of AIN at different temperatures and the fractures of high-temperature tensile samples were observed by using TEM （transmission electron microscope） and SEM （scanning electron microscope）. The factors affecting the brittle temperature zone were discussed.

关键词： continuous casting slab brittle temperature zone tensile strength,ductility simulation

Analytical Investigation of Prior Austenite Grain Size Dependence of Low Temperature Toughness in Steel Weld Metal

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Journal of Materials Science & Technology 2012年第3期28卷 241-248页

作者： x.f. Zhang P. Hall H. Terasak M. Sato Y. Komizo Joining and Welding Research Institute Osaka University 11-1 Mihogaoka Ibaraki Osaka 56%0047 Japan Technical Development Department Welding Business Kobe Steel Ltd. 100-1 Miyamae Fujisawa Kanagawa 251- 8551 Japan

Prior austenite grain size dependence of the low temperature impact toughness has been addressed in the bainitic weld metals by in situ ***,decreasing the grain size is the only approach by which both the strength and the toughness of a steel are ***,low carbon bainitic steel with small grain size shows a weakening of the low temperature impact toughness in this *** direct tracking of the morphological evolution during phase transformation,it is found that large austenite grain size dominates the nucleation of intragranular acicular ferrite,whereas small austenite grain size leads to grain boundary nucleation of *** kinetics information will contribute to meet the increasing low temperature toughness requirement of weld metals for the storage tanks and offshore structures.

关键词： In situ observation Prior austenite grain size Low temperature toughness Intragranular nucleation Grain boundary nucleation