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Fatigue Damage Mechanism of AL6XN Austenitic Stainless Steel at High Temperatures

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Acta Metallurgica Sinica(English Letters) 2020年第6期33卷 799-807页

作者： Yanyan Hong penglin gao Hongjia Li Changsheng Zhang Guangai Sun Key Laboratory of Neutron Physics Institute of Nuclear Physics and ChemistryCAEPMianyang 621900China Key Laboratory for Anisotropy and Texture of Materials School of Materials Science and EngineeringNortheastern UniversityShenyang 110004China

By the combination of transmission electron microscope, neutron diffraction and small-angle neutron scattering methods, mechanical fatigue behavior of AL6XN austenitic stainless steel was investigated in the temperature range of 400–600 °C. At 400 °C, in addition to the occurrence of dynamic strain aging, the formation of short-range order was evidenced from the forbidden electron diffraction spot of 1/3 {422} in face-centered cubic(fcc) structure viewed down [111] zone axis, which facilitate the planar slip mode of dislocation and result in the work hardening during the fatigue deformation. The fatigue damage is mainly dominated by the accumulation of planar slip band and the interaction among various slip systems. With increasing temperature, precipitates of chi phase, Laves phase and sigma phase were formed during the fatigue tests at 500 and 600 °C. An increase in precipitation content at 600 °C has also been confirmed by both scanning electron microscope and small-angle neutron scattering analysis. The dislocation pileup originating from the uncoordinated deformation between precipitate and austenitic matrix is an important fatigue damage leading to crack. The continuous cycle softening behavior was also observed on the fatigue curve at 600 °C, which is considered to be caused by dynamic recovery.

关键词： Precipitates Low-cycle fatigue Austenitic stainless steel Small-angle neutron scattering Planar slip bands

Theory of non-Hermitian topological whispering gallery

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npj Computational Materials 2022年第1期8卷 2308-2314页

作者： RenéPernas-Salomón Li-Yang Zheng Zhiwang Zhang penglin gao Xiaojun Liu Ying Cheng Johan Christensen Department of Physics Universidad Carlos III de MadridMadridSpain School of Science Shenzhen Campus of Sun Yat-sen UniversityShenzhen518107China Department of Physics MOE Key Laboratory of Modern AcousticsCollaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjingChina State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai200240China Institute of Vibration Shock and NoiseShanghai Jiao Tong UniversityShanghai200240China IMDEA Materials Institute Calle Eric Kandel228906GetafeMadridSpain

Topological insulators have taken the condensed matter physics scenery by storm and captivated the interest among scientists and materials engineers ***,this arena which was initially established and profoundly studied in electronic systems and crystals,has sparked a drive among classical physicists to pursue a wave-based analogy for sound,light and *** the latest efforts combining valley-contrasting topological sound with non-Hermitian ingredients,*** et al.[Nature 597,655(2021)]employed thermoacoustic coupling in sonic lattices whose elementary building blocks are coated with electrically biased carbon nanotube *** this contribution,we take a theoretical and numerical route towards understanding the complex acoustic interplay between geometry and added acoustic gain as inspired by the aforesaid *** complex bulk and edge states predictions and computations of mode-split resonances using whispering gallery configurations,we also predict an acoustic amplitude saturation in dependence on the activated coated *** foresee that our computational advances may assist future efforts in exploring thermoacoustic topological properties.

关键词： properties topological analogy

煤矿井下复杂地形条件综采面综采技术的应用研究

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山西化工 2020年第3期40卷 148-149,157页

作者：高鹏林大同煤矿集团临汾宏大豁口煤业有限公司山西临汾041000

综采技术直接关系到煤矿井下综采作业时的效率、经济性和安全性,是煤矿生产的核心,针对复杂地形条件下煤炭综采作业效率低、顶煤出采率低,综采成本高、安全性差的现状,提出了一种煤矿井下复杂地形条件下的综采面综采技术方案,专门针对... 详细信息

综采技术直接关系到煤矿井下综采作业时的效率、经济性和安全性,是煤矿生产的核心,针对复杂地形条件下煤炭综采作业效率低、顶煤出采率低,综采成本高、安全性差的现状,提出了一种煤矿井下复杂地形条件下的综采面综采技术方案,专门针对复杂地形条件下的综采特点,采用多工艺联合旋转综采作业方案,优化巷道支护方案、综采作业流程等,极大地提升了井下综采作业的效率和安全性。

关键词：煤矿复杂地形综采方案顶板控制

Record-high efficiency perovskite LEDs achieved by accelerating radiative recombination

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Science China Materials 2024年第9期67卷 3039-3040页

作者： Feng gao Department of Physics Chemistry and BiologyLinköping UniversityLinköping58183Sweden

Light-emitting diodes(LEDs)have revolutionized the lighting and displays due to their superior energy *** increasing demand for more efficient and brighter thin-film LEDs in flat-panel displays and solid-state lighting applications has driven extensive research into perovskite materials,which show great promise for high brightness and efficiency.

关键词： lighting radiative high

Stress tensor determination by modified hydraulic tests on pre-existing fractures:Method and stress constraints

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第5期16卷 1637-1648页

作者： Guiyun gao Chenghu Wang Ke gao National Institute of Natural Hazards Ministry of Emergency Management of ChinaBeijing100085China Beijing Engineering Research Center of Earthquake Observation Beijing100085China Key Laboratory of Compound and Chained Natural Hazards Dynamics Ministry of Emergency Management of ChinaBeijing100085China Department of Earth and Space Sciences Southern University of Science and TechnologyShenzhen518055China

The hydraulic testing of pre-existing fractures(HTPF)is one of the most promising in situ stress measurement methods,particularly for three-dimensional stress tensor ***,the stress tensor determination based on the HTPF method requires at least six tests or a minimum of 14-15 tests(under different conditions)for reliable *** this study,we modified the HTPF method by considering the shear stress on each pre-existing fracture,which increased the number of equations for the stress tensor determination and decreased the number of tests *** shear stresses were attributed to different fractures by random sampling;therefore,the stress tensors were obtained by searching for the optimal solution using the least squares criterion based on the Monte Carlo ***,we constrained the stress tensor based on the tensile strength criterion,compressive strength criterion,and vertical stress *** inverted stress tensors were presented and analyzed based on the tensorial nature of the stress using the Euclidean mean stress *** stress-measurement campaigns in Weifang(Shandong Province,China)and Mercantour road tunnel(France)were implemented to highlight the validity and efficiency of the modified HTPF(M-HTPF)*** results showed that the M-HTPF method can be applied for stress tensor inversion using only three to four tests on pre-existing fractures,neglecting the stress *** inversion results were confined to relatively small distribution dispersions and were significantly reliable and stable due to the shear stresses on the fractures and the stress constraints *** M-HTPF method is highly feasible and efficient for complete stress tensor determination in a single borehole.

关键词： Stress tensor Hydraulic tests on pre-existing fractures Mean stress Stress constraint Hydraulic fracturing

Thermal and mechanical behavior of casting copper alloy wheel during wheel and belt continuous casting process

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China Foundry 2024年第1期21卷 82-90页

作者： Kun gao Yan Peng School of Mechanical Engineering Yanshan UniversityQinhuangdao 066004HebeiChina

To investigate the thermal and mechanical behavior of casting wheel,a two-dimensional thermoelastic-plastic finite element model was used to predict the temperature,stress and distortion distribution of the casting wheel during the wheel and belt continuous casting *** effects of grinding thickness and casting speed on the thermal and mechanical behaviors of the center of the hot face of the casting wheel were discussed in *** each rotation,the casting wheel passes through four different spray *** results show that the temperature distribution of the casting wheel in different spray zones is similar,the temperature of the hot face is the highest and the temperature reaches the peak in the spray zoneⅢ.The stress and distortion depend on the temperature distribution,and the maximum stress and distortion of the hot face are 358.2 MPa and 1.82 mm,*** temperature at the center of the hot face decreases with increasing grinding thickness and increases with increasing casting speed.

关键词： casting wheel finite element model grinding thickness casting speed hot face spray zones

Numerical simulation of fluid flow and free surface fluctuations during wheel and belt casting process

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Journal of Iron and Steel Research International 2024年第5期31卷 1117-1126页

作者： Kun gao Yan Peng National Engineering Research Center for Equipment and Technology of Cold Strip Rolling Yanshan UniversityQinhuangdao066004HebeiChina

The unstable fluid flow and severe free surface fluctuations in the wheel and belt caster can affect the quality of the cast *** lower level height tends to entrap inclusions in the molten *** the other hand,the higher level height makes the production process more dangerous due to the overflow of high temperature fluid from the mold.A computational model of the molten metal pouring process was *** transient fluid flow and free surface fluctuations behavior were calculated using the three-dimensional large eddy simulation model and the volume of fluid *** results show that the flow velocity of the main jet gradually decreases under the influence of the low kinetic energy fluid in the *** is an obvious oscillation in the tail of the jet,while the flow field is asymmetric in *** jet is closer to the inside radius side due to the Coanda effect,and there is a recirculation zone on the inside radius and the outside radius respectively,according to the 10 s time-averaged *** with the industrial observation and simulation results,the shape of the free surface is a wave that varies with *** addition,the free surface height is lowest and the flow velocity is highest in the region near the jet.

关键词： Fluid flow Free surface Wheel and belt caster Large eddy simulation Volume of fluid method

On the core entropy of Newton maps

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Science China Mathematics 2024年第1期67卷 77-128页

作者： Yan gao Department of Mathematics Shenzhen UniversityShenzhen 518060China

In this paper,we define the core entropy for postcritically-finite Newton maps and study its continuity within this *** show that the entropy function is not continuous in this family,which is different from the polyn... 详细信息

关键词： core entropy extended Newton graph critical marking polynomial Newton map

Durable poly(binaphthyl-co-p-terphenyl piperidinium)-based anion exchange membranes with dual side chains

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Journal of Energy Chemistry 2024年第2期89卷 324-335,I0008页

作者： Weiting gao Xuelang gao Qiugen Zhang Aimei Zhu Qinglin Liu Department of Chemical&Biochemical Engineering Fujian Provincial Key Laboratory of Theoretical and Computational ChemistryThe College of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005FujianChina Department of Chemistry Pohang University of Science and Technology(POSTECH)Pohang 790-784South Korea

Building well-developed ion-conductive highways is highly desirable for anion exchange membranes(AEMs).Grafting side chain is a highly effective approach for constructing a well-defined phaseseparated morphological structure and forming unblocked ion pathways in AEMs for fast ion *** of side chains can further enhance phase separation due to the superhydrophobic nature of fluorine ***,their electronic effect on the alkaline stability of side chains and membranes is rarely ***,fluorine-containing and fluorine-free side chains are introduced into the polyaromatic backbone in proper configuration to investigate the impact of the fluorine terminal group on the stability of the side chains and membrane *** poly(binaphthyl-co-p-terphenyl piperidinium)AEM(QBNp TP)has the highest molecular weight and most dimensional stability due to its favorable backbone arrangement among ortho-and meta-terphenyl based ***,by introducing both a fluorinated piperidinium side chain and a hexane chain into the p-terphenyl-based backbone,the prepared AEM(QBNp TP-QFC)presents an enhanced conductivity(150.6 m S cm^(-1))and a constrained swelling at 80℃.The electronic effect of fluorinated side chains is contemplated by experiments and *** results demonstrate that the presence of strong electro-withdrawing fluorine groups weakens the electronic cloud of adjacent C atoms,increasing OH^(-)attack on the C atom and improving the stability of piperidinium *** QBNp TP-QFC possesses a robust alkaline stability at 80℃(95.3%conductivity retention after testing in 2 M Na OH for 2160 h).An excellent peak power density of 1.44 W cm^(-2)and a remarkable durability at 80℃(4.5%voltage loss after 100 h)can be observed.

关键词： Anion exchange membranes Backbone structure Fluorinated side chain Alkaline stability