检索结果-南通市图书馆

Journal of Iron and Steel Research(International) 2023年第9期30卷 1843-1853页

作者： Tian-yu Zhang Ling-yu Wang Yu Wang Jun Hu hong-shuang di Wei Xu State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819LiaoningChina

Low-temperature ausforming(LT-AF)prior to bainitic transformation leads to a noticeable acceleration of bainitic transformation kinetics;however,the effect of LT-AF on the retained austenite(RA)features and the resulting mechanical properties is still unclear.LT-AF was applied to ultrahigh-strength bainitic steel before austempering.The deformation behavior and the resulting dislocation substructures were investigated by thermomechanical simulator and transmission electron microscopy(TEM).The planar dislocation structures produced during deformation at 350℃ accelerate the bainitic transformation kinetics during isothermal holding.The effect of LT-AF on the bainitic transformation kinetics and the features of RA was elucidated via dilatometer measurement,TEM,scanning electron microscopy,and X-ray diffraction.It is observed that LT-AF not only retains more RA content but also facilitates improved RA stability.This trend is mainly due to the large amounts of planar dislocations in RA and bainitic laths inherited from undercooled austenite caused by LT-AF,the decrease in bainitic sheaves size,and the increase in filmy RA content compared to the sample without ausforming.A large fraction of filmy RA with high stability and the refinement of bainitic sheaves obtained by LT-AF remarkably enhance the strain hardening capacity and achieve significantly better ductility compared to the directly austempered sample.

关键词： Ultrahigh-strength bainitic steel Bainitic transformation Low-temperature ausforming Retained austenite Strain hardening rate

Effect of Heat-Treatment Schedule on the Microstructure and Mechanical Properties of Cold-Rolled Dual-Phase Steels

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2015年第9期28卷 1141-1148页

作者： Yong-Gang Deng hong-shuang di Jie-Cen Zhang State Key Laboratory of Rolling and Automation Northeastern University

Low-carbon （0.08 wt% C） steel has been subjected to three different heat treatments to obtain dual-phase steels with different microstructures. An understanding of structure-property was established through tensile tests, in conjunction with scanning electron microscope and transmission electron microscope. The results show that the steel after intermediate quenching （IQ） consisting of fine and fibrous martensite exhibited the intermediate strength, highest elongation and the best comprehensive performance of mechanical properties, whereas the steel subjected to intercritical annealing （IA） produced a network martensite along ferrite grain boundaries, having the lowest strength and intermediate elongation. Besides, step quenching （SQ） resulted in a coarse and blocky ferrite-martensite microstructure showing the worst mechanical properties of the three different heat-treatment conditions. The strain-hardening behavior was studied through the modified Crussard- Jaoul model, indicating two stages of strain-hardening behavior for all three samples. The highest magnitude of strain- hardening ability was obtained by IQ annealing routes. The analysis of the fractured surface revealed that ferrite/martensite interfaces are the most susceptible for microvoid nucleation. However, martensite microcracks were also observed in SQ sample, and the microvoids are nucleated within the ferrite grain in IA sample as well. The variations in strength, elongation, strain-hardening behavior and fracture mechanism of the steel with different heat-treatment schedules were further discussed in relation to the microstructural features.

关键词： Dual-phase steel Heat-treatment schedule Strain-hardening behavior Fracture mechanism

On significance of initial microstructure in governing mechanical behavior and fracture of dual-phase steels

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research(International) 2018年第9期25卷 932-942页

作者： Yong-gang Deng hong-shuang di R. D. K. Misra State Key Laboratory of Rolling and Automation Northeastern University Shenyang 110819 Liaoning China Laboratory for Excellence in Advanced Steel Research University of Texas El Paso TX 79968 USA

different initial microstructures were obtained through combination of intercritical annealing and cold-rolling. Subsequently, steels with different microstructures of ferrite-pearlite （FP）, ferrite-martensite （FM） and complete martensite （M） were intercritically annealed at 780 ℃ for 5 min and water quenched to obtain ferrite-martensite microstructure. The significance of initial microstructures on ultimate microstructure, mechanical properties, strain-hardening ability and fracture behavior in dual-phase steels has been elucidated. Initial microstructures of FP, FM and M yielded different martensite morphologies, notably chain-like network structure, fine and fibrous martensite structure, respectively. Furthermore, with increasing martensite content in the initial microstructure, the average grain size of ferrite was significantly refined from about 12.3 to 2.1 μm, which results in that the ultimate tensile strength （UTS） and yield strength were increased, total elongation remained unaffected, and uniform elongation （UE） and strain-hardening ability were increased. A comparison of mechanical properties for different initial microstructures suggested that when the initial microstructure was complete martensite, the steel had excellent mechanical properties, with UTS × UE of 122.5 J cm^-3, which was 24% greater than the conventional continuously annealed steels with ferrite-pearlite initial microstructure （98.8 J cm^-3）. The variation in tensile properties, strain-hardening ability and fracture mechanism of steels with different initial microstructures were discussed in relation to the ultimate microstructures.

关键词： Dual-phase steel Microstructure Mechanical property Strain-hardening Fracture

Hot Deformation Behavior and Processing Maps of a Medium Manganese TRIP Steel

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2019年第8期32卷 1021-1031页

作者： Ning Yan hong-shuang di Hui-Qiang Huang R.D.K.Misra Yong-Gang Deng State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China Laboratory for Excellence in Advanced Steel Research Department of MetallurgicalMaterials and Biomedical EngineeringUniversity of Texas El PasoEl PasoTX 7996&USA

The hot deformation behavior of a medium-Mn steel was studied in terms of hot compression flow curves in the temperature range of 850–1050 ℃ and strain rates of 0.05–10 s-1.The thermo-mechanical analysis was carried out and suggested that the microstructure during deformation was completely austenite which had high tendency for dynamic recrystallization(DRX).The flow behavior was characterized by significant flow softening at deformation temperatures of 950–1050 ℃ and lower strain rates of 0.05–5 s-1, which was attributed to heating during deformation, DRX and flow instability.A step-by-step calculating procedure for constitutive equations is proposed.The verification of the modified equations indicated that the developed constitutive models could accurately describe the flow softening behavior of studied steel.Additionally, according to the processing maps and microstructure analysis, it suggested that hot working of medium Mn steel should be carried out at 1050 ℃, and the strain rate of 0.05–10 s-1 resulted in significantly recrystallized microstructures in the in steel.The flow localization is mainly flow instability mechanism for experimental steel.

关键词： Medium-Mn steel Hot deformation behavior Constitutive equations Flow instability mechanism Recrystallized microstructure

Effect of cooling time t8/5 on microstructure and toughness of Nb-Ti- Mo microalloyed C-Mn steel

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research(International) 2018年第10期25卷 1078-1085页

作者： Xiao-nan Wang Xia-ming Chen Feng Wen Peng-fei Guo Lei Yang Qian Yan hong-shuang di Shagang School of Iron and Steel Soochow University Suzhou 215021 Jiangsu China State Key Laboratory of Rolling and Automation Northeastern University Shenyang 110819 Liaoning China

In order to further optimize welding process of Nb-Ti-Mo microalloyed steel, welding thermal cycles on coarse-grained heat-affected zone （CGHAZ） of welded joints were simulated using Gleeble 1500. The microstructure and low-temperature impact fracture were investigated using a scanning electron microscope and a pendulum impact machine, respectively. Moreover, the relationship between cooling time ts/5 and the microstructure of CGHAZ was discussed, and the effect of microstructure on impact toughness was also studied. As cooling time increased, martensite fraction decreased from 97.8% （3 s） to 3.0% （60 s）. The fraction of martensite/austenite （M/A） constituent increased from 2.2% （3 s） to 39.0% （60 s）, its shape changed from granular to strip, and the maximum length increased from 2.4 μm （3 s） to 7.0 μm （60 s）. As cooling time increased, the prior austenite grain size increased from 34.0 μm （3 s） to 49.0 gm （60 s）, the impact absorption energy reduced from 101.8 J （5 s） to 7.2 J （60 s）, and the fracture mechanism changed from quasi-cleavage fracture to cleavage fracture. The decreased toughness of CGHAZ was due to the reduction of lath martensite-content, coarsening of original austenite grain, and increase and coarsening of M/A constituent. The heat input was controlled under 7 kJ cm-1 during actual welding for these steels.

关键词： Microalloyed C-Mn steel Cooling time - Impact absorption energy M/A constituent Coarse-grained heataffected zone Heat input

Gastrointestinal contrast-enhanced ultrasonography for diagnosis and treatment of peptic ulcer in children

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2024年第7期30卷 705-713页

作者： Yu-Hua Zhang Zhi-Hua Xu shuang-shuang Ni hong-Xia Luo Department of Ultrasound The Second Affiliated Hospital of Wenzhou Medical UniversityWenzhou 325000Zhejiang ProvinceChina

BACKGROUND The detection rate of peptic ulcer in children is improving,with development of diagnostic procedures.Gastroscopy is the gold standard for the diagnosis of peptic ulcer,but it is an invasive procedure.Gastrointestinal contrast-enhanced ultrasonography(CEUS)has the advantages of being painless,noninvasive,nonradioactive,easy to use,and safe.AIM To investigate the clinical value of CEUS for diagnosis and treatment of peptic ulcer in children.METHODS We investigated 43 children with digestive tract symptoms in our hospital from January 2021 to June 2022.All children were examined by routine ultrasound,gastrointestinal CEUS,and gastroscopy.The pathological results of gastroscopy were taken as the gold standard.Routine ultrasonography was performed before gastrointestinal CEUS.Conventional ultrasound showed the thickness of the gastroduodenal wall,gastric peristalsis,and the adjacent organs and tissues around the abdominal cavity.Gastrointestinal CEUS recorded the thickness of the gastroduodenal wall;the size,location and shape of the ulcer;gastric peristalsis;and adjacent organs and tissues around the abdominal cavity.The results of routine ultrasound and gastrointestinal ultrasound were compared with those of gastroscopy to evaluate the diagnostic results and coincidence rate of routine ultrasound and gastrointestinal CEUS.All children received informed consent from their guardians for CEUS.This study was reviewed and approved by the hospital medical ethics committee.RESULTS Among the 43 children,17(15 male,2 female)were diagnosed with peptic ulcer by gastroscopy.There were 26 children with nonpeptic ulcer.There were eight cases of peptic ulcer and 35 of nonpeptic ulcer diagnosed by conventional ultrasound.The diagnostic coincidence rate of peptic ulcer in children diagnosed by conventional ultrasound was 79.1%(34/43),which was significantly different from that of gastroscopy(P=0.033).It indicates that the coincidence rate of gastrointestinal contrast-enhanced ultrasound and gastroscope is low.Fifteen cas

关键词： Contrast-enhanced ultrasound Peptic ulcer Children Gastrointestinal tract Abdominal pain Acoustic contrast agent

Effect of aflibercept combined with triamcinolone acetonide on aqueous humor growth factor and inflammatory mediators in diabetic macular edema

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Ophthalmology(English edition) 2024年第2期17卷 297-303页

作者： De-shuang Li hong-Xia Liao Jing-Lin Zhang Bo Qin Shenzhen Aier Eye Hospital Aier Eye HospitalJinan UniversityShenzhen 518031Guangdong ProvinceChina Guangzhou Aier Eye Hospital Jinan UniversityGuangzhou 510040Guangdong ProvinceChina

AIM:To investigate the efficacy of aflibercept combined with sub-tenon injection of triamcinolone acetonide(TA)in treating diabetic macular edema(DME)and to examine changes in growth factors and inflammatory mediator levels in aqueous humor after injection.METHODS:Totally 67 DME patients(67 eyes)and 30 cataract patients(32 eyes)were enrolled as the DME group and the control group,respectively.The DME group was divided into the aflibercept group(34 cases)and the aflibercept combined with TA group(combined group,33 cases).The aqueous humor of both groups was collected during the study period.The aqueous levels of vascular endothelial growth factor(VEGF),monocyte chemoattractant protein-1(MCP-1),interleukin-6(IL-6),interleukin-8(IL-8),and interleukin-1β(IL-1β)were detected using a microsphere suspension array technology(Luminex 200TM).Aqueous cytokines,best-corrected visual acuity(BCVA),central macular thickness(CMT),and complications before and after treatment were compared between the aflibercept group and combined group.RESULTS:The concentrations of VEGF,MCP-1,IL-6,and IL-8 in the aqueous humor were significantly higher in the DME group than those of the control group(all Pdifferent after 1 and 2mo of treatment(Pdifference was not statistically significant after 3mo of treatment(P>0.05).CONCLUSION:The cytokines VEGF,MCP-1,IL-6,and IL-8 in the aqueous humor of DME patients are significantly increased.Aflibercept and aflibercept combined with TA have good efficacy in DME patients,can effectively reduce CMT,improve the patient’s vision,and have high safety.Aflibercept combined with TA can quickly downregulate the aqueous humor cytokines and help to relieve macular edema rapidly.However,the long-term efficacy is comparable to that of aflibercept alone

关键词： diabetic macular edema aqueous humor cytokines aflibercept triamcinolone acetonide

Attaining synergetic equilibrium of electrical conductivity and tensile strength in GQDs@GN/Cu composites through multi-scale intragranular and intergranular reinforcements

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2024年第1期43卷 366-379页

作者： shuang-Yin Zhang Liang Liu Rui Bao Jian-hong Yi Sheng-Da Guo Faculty of Materials Science and Engineering Kunming University of Science and TechnologyKunming 650093China Key Laboratory of Advanced Materials of Yunnan Province Kunming University of Science and TechnologyKunming 650093China Faculty of Materials Metallurgy and Chemistry Jiangxi University of Science and TechnologyGanzhou 341000China

The configuration and quality of reinforcements, as well as the robustness of interfacial bonding,holding a critical significance in determining the concurrence between electrical conductivity and mechanical strength in metal matrix composites. In this study, citric acid was employed as the precursor for synthesizing multiscale carbon nanomaterials(graphene quantum dots and graphene, abbreviated as GQDs and GN). The GQDs@GN/Cu composites were fabricated through a segmented ball milling process in conjunction with subsequent spark plasma sintering(SPS). The intragranular GQDs and intergranular GQDs@GN had synergistically reinforced Cu composites through Orowan strengthening, load transfer strengthening and refinement strengthening. Furthermore,the robust interface bonding between GQDs@GN and Cu effectively mitigated interfacial impedance stemming from electron-boundary scattering. The yield strength and ultimate tensile strength of the GQDs@GN/Cu composites were recorded as 270 and 314 MPa, respectively, representing an improvement of 92 and 28% over pure Cu, while maintaining electrical conductivity at a level comparable to that of pure Cu. This study advances the understanding of the possibility of realizing a synergistic compatibility between electrical conductivity and mechanical strength in Cu composites.

关键词： Cu matrix composites Interface bonding Mechanical property Graphene quantum dots(GQDs) Electrical conductivity

Bunch-length measurement at a bunch-by-bunch rate based on time–frequency-domain joint analysis techniques and its application

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2024年第4期35卷 165-175页

作者： hong-shuang Wang Xing Yang Yong-Bin Leng Yi-Mei Zhou Ji-Gang Wang Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800China University of Chinese Academy of Sciences Beijing 100049China National Synchrotron Radiation Laboratory University of Science and Technology of ChinaHefei 230026China Shanghai Advanced Research Institute Chinese Academy of SciencesShanghai 201204China

This paper presents a new technique for measuring the bunch length of a high-energy electron beam at a bunch-by-bunch rate in storage rings.This technique uses the time–frequency-domain joint analysis of the bunch signal to obtain bunch-by-bunch and turn-by-turn longitudinal parameters,such as bunch length and synchronous phase.The bunch signal is obtained using a button electrode with a bandwidth of several gigahertz.The data acquisition device was a high-speed digital oscilloscope with a sampling rate of more than 10 GS/s,and the single-shot sampling data buffer covered thousands of turns.The bunch-length and synchronous phase information were extracted via offline calculations using Python scripts.The calibration coefficient of the system was determined using a commercial streak camera.Moreover,this technique was tested on two different storage rings and successfully captured various longitudinal transient processes during the harmonic cavity debugging process at the Shanghai Synchrotron Radiation Facility(SSRF),and longitudinal instabilities were observed during the single-bunch accumulation process at Hefei Light Source(HLS).For Gaussian-distribution bunches,the uncertainty of the bunch phase obtained using this technique was better than 0.2 ps,and the bunch-length uncertainty was better than 1 ps.The dynamic range exceeded 10 ms.This technology is a powerful and versatile beam diagnostic tool that can be conveniently deployed in high-energy electron storage rings.

关键词： Bunch-by-bunch diagnostic Bunch-length measurement Synchronous phase measurement Joint time–frequency-domain analysis Longitudinal instability

Effect of different bottom blowing elements on stirring characteristics of molten bath in converter

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research(International) 2024年第2期31卷 368-376页

作者： Ming Lv shuang-ping Chen hong-min Guo Yi-jie Hao Xiang-dong Xing School of Metallurgical Engineering Xi’an University of Architecture and TechnologyXi’an710055ShaanxiChina Shaanxi Longmen Steel Company Hancheng715405ShaanxiChina

The bottom blowing element is the key equipment to ensure the bottom blowing effect of the converter.Three types of bottom blowing elements,dispersive type(D1),double circular seam(D2)and straight cylinder type(D3),were built,and the effects of bottom blowing element type on molten bath flow,wall erosion and furnace bottom erosion were simulated.It was found that when the bottom blowing elements of dispersive type(D1)and double circular seam(D2)were used,the dead zone area in the lower part of the molten bath was smaller,and the high-speed zone area was larger;therefore,the stirring effect on the bottom melt was better.When the straight cylinder type(D3)bottom blowing element was used,the gas penetrated the molten bath at a faster rate to reach the surface of molten bath and failed to disperse in the bottom molten bath,and the wall shear stress near the nozzle outlet was larger.When argon was blown by three different bottom blowing elements,the area of the wall shear stress greater than 3 Pa was 4.8,5.6 and 8.7 cm2,respectively,within 0.2 m of the bottom blowing nozzle outlet.

关键词： Converter steelmaking Bottom blowing element Molten bath stirring Wall erosion