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Microstructure transformation of X70 pipeline steel welding heat-affected zone

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Rare Metals 2014年第4期33卷 493-498页

作者： Hui li Jing-Long liang yun-li feng Dong-Xing Huo College of Metallurgy and Energy Hebei United University

The continuous cooling transformation curve of heat-affected zone （HAZ） of X70 pipeline steel was mea- sured by Gleeble-3500 thermal mechanical simulator, optical microscope （OM） and hardness analysis. The microstructure transformation rule at different cooling rates and solution behaviors of microalloy carbonitride during heating process of simulated specimens were investigated. When the cooling rate changes from 10 to 20 ℃.s-l, microstructures at HAZ are identified as granular bainite, lathy bainite, and quasi-polygonal ferrite. This micro- structure is featured with fine ferrite grains, martensite/ austenite islands dispersed, high-density dislocations, and fine carbonitride particles, resulting in improving the strength and toughness of HAZ. With the cooling rate increasing to above 40 ℃.s-1, the microstructure is pre- dominantly coarse lathy bainite with clear primary aus- tenite grain boundary. While the cooling rate decreases to below 1 ℃.s-1, a fairly small amount of pearlite can be observed at the boundaries. The strength and toughness of HAZ are deteriorated because of coarse grains among these microstructures. Most of microalloy carbonitrides in HAZ could be dissolved in the matrix during heating process. A few of TiN particles existing as residues in the matrix can prevent austenite grain from growing, and then improve the strength and toughness of HAZ.

关键词： X70 pipeline steel Heat-affected zone Microstructure transformation Acicular ferrite

Constitutive Model of Warm Deformation Behavior of Medium Carbon Steel

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Journal of Iron and Steel Research International 2016年第9期23卷 940-948页

作者： Hong-bin li yun-li feng Tao YAN En-lin YU National Engineering Research Center for Equipment and Technology of Cold Strip Rolling Yanshan University College of Metallurgy and Energy North China University of Science and Technology Equipment Manufacturing College Hebei University of Engineering

The compressive behaviors of medium carbon steel specimens were investigated over a wide range of tem- peratures and strain rates using a Gleeble-3500 thermo-simulation machine. The results show that the flow stress in- creased with strain at first, and then gradually decreased after reaching a peak value. The flow stress softening rate at a high strain rate was larger than that at a low strain rate. The effects of deformation heating and friction on flow stress were analyzed. A new friction correction method, wherein the effect of strain on frictional coefficient was con- sidered, was established here. The stresses revised by the new method deviated from the measured stresses with in- creasing strain. Meanwhile, the apparent frictional coefficient variation law with strain was obtained. The frictional coefficient increased as the strain increased and then slightly decreased after maintaining a constant value. The stress was corrected by considering deformation heating. The accuracy of the temperature correction method was verified using a special experiment. The results of the verification experiment show that the temperature correction method exhibited a good accuracy in calculating the variation of stress caused by deformation heating. A constitutive model considering strain was proposed here to describe the deformation behaviors. Compared with experimental data, the modified constitutive model exhibited a good accuracy as to constitutive correlation.

关键词： friction correction temperature correction deformation heating flow stress constitutive model

Dependence of tensile properties on microstructural features of bimodal-sized ferrite/cementite steels

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Journal of Iron and Steel Research International 2017年第1期24卷 67-76页

作者： Jiang-li Ning yun-li feng Ming-ming Wang Shen-bai Zheng Jie li College of Metallurgy and Energy North China University of Science and TechnologyTangshan 063009HebeiChina

A medium-carbon steel was processed through different warm rolling techniques,and the microstructural features with bimodal grain size distribution were found to be *** combination of strength and ductility was ameliorated in the steel processed through warm rolling characterized by biaxial *** enhanced strength is attributed to the densely distributed fine intragranular cementite particles and the small grain size in the coarse grain *** enhanced uniform elongation is due to the improved work hardening behavior at the large-strain *** work hardening behavior is predominantly ascribed to the finely dispersed intragranular *** relatively small grain size with nearly equiaxed shape in the coarse grain regions helps stabilize the uniform deformation to a large strain.

关键词： Tensile property Ferrite/cementite steel Bimodal-sized structure Warm rolling Work hardening rate

Balanced solubility product and enthalpies of formation of Nb compounds in 0.09 % oriented silicon steel

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Rare Metals 2013年第3期32卷 318-322页

作者： Hui li yun-li feng Dan Zhang Meng Song Da-Qiang Cang School of Metallurgical and Ecological Engineering University of Science and Technology Beijing School of Metallurgy and Energy Hebei United University

Balance solubility products and enthalpy of for- mation for NbC0.75, NbC0.85, NbC0.88, NbC and NbN in oriented silicon steels were calculated and compared quali- tatively. Meanwhile, the mixing enthalpies of these five Nb compounds were calculated based on Miedema Model. The results show that the solubility products of Nb compounds in ferrite and austenite meet the following relationship, NbC0.75 〉 NbC0.85 〉 NbC0.88 〉 NbC 〉 NbN and NbN has the minimum enthalpy of formation. It indicates that NbN easily precipitate out, but it is more difficult for NbC0.75.

关键词： Oriented silicon steel Nb compounds Solubility formula Enthalpy of formation

Tension-Compression Yield Asymmetry Influenced by the Variable Deformation Modes in Gradient Structure Mg Alloys

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Acta Metallurgica Sinica(English Letters) 2020年第2期33卷 252-266页

作者： Jiang-li Ning Bo Xu yun-li feng Xu-Dong li Xin-Kang li Wei-Ping Tong College of Metallurgy and Energy North China University of Science and TechnologyTangshan 063210China Key Laboratory of Electromagnetic Processing of Materials Ministry of EducationNortheastern UniversityShenyang 110004China

Surface mechanical attrition treatment(SMAT) was carried out on hot-rolled AZ31 Mg samples along two orthogonal directions;as a result,two types of gradient structures with different grain sizes and texture components in different layers were *** tension-compression yield asymmetry(YA) was studied using samples with different thicknesses,in order to elucidate the effect of combinations of variable deformation modes operating in different layers of the two oriented SMAT *** 0° oriented SMAT sample containing layers with strong basal texture displayed significant YA,because of either dislocation slip or extension twinning domination during tension or *** contrast,the 90° oriented SMAT sample containing layers with coexisting orthogonal texture components had an obviously weakened YA,which was attributed to the multi-deformation modes cooperating during tension or compression,i.e.,extension twinning or detwinning in conjunction with dislocation slips,leading to close yield stresses compared between tension and compression.

关键词： Mg alloy Gradient structure Yield asymmetry Texture Deformation mechanism

Nanoscratching and mechanical behaviors of high-entropy alloys with different phase constituents

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Journal of Iron and Steel Research International 2019年第11期26卷 1240-1248页

作者： Jiang-li Ning yun-li feng Xu-dong li Qi-bo Deng Yong-jiang Huang College of Metallurgy and Energy North China University of Science and TechnologyTangshan 063210HebeiChina Tianjin Key Laboratory of Advanced Functional Porous Materials Institute for New Energy Materials and Low-Carbon TechnologiesSchool of Materials Science and EngineeringTianjin University of TechnologyTianjin 300384China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001HeilongjiangChina

High-entropy alloys(HEAs)exhibit unique microstructural features and properties in nanoscale and atomic scale because of their multi-element alloy *** nanoscratching behaviors of three HEAs with different phase constituents,relative to the microstructure and mechanical properties of the HEAs,were *** typical phase constituents were selected:face-centered cubic(FCC)structure,body-centered cubic(BCC)structure,and a dual-phase structure containing both FCC and BCC *** the fact that the FCC alloy has the highest ductility and strain hardening capability,it exhibited inferior scratch resistance due to the over-softening of *** to the brittle failure mode,the BCC alloy hardly exhibited desirable scratch resistance despite its highest *** contrast,the nanostructured dual-phase alloy exhibited the best scratch resistance because of its good combination of strength and ductility,as well as the ductile failure *** research suggests that the HEA with structure comprising nanoscale hard and soft phases is desirable for nanoscratch resistance,and possesses appropriate hardness for industrial applications.

关键词： High-entropy alloy Nanoscratch Mechanical property Microstructure-Failure mode

Translocator protein ligand, YL-IPA08, attenuates lipopolysaccharide-induced depression-like behavior by promoting neural regeneration

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Neural Regeneration Research 2018年第11期13卷 1937-1944页

作者： Xiao-Ying Zhang li-Ming Zhang Wei-Dong Mi yun-feng li Anesthesia and Operation Center Chinese PLA General Hospital Beijing China State Key Laboratory of Toxicology and Medical Countermeasures Beijing China

Translocator protein has received attention for its involvement in the pathogenesis of depression. This study assessed the effects of the new translocator protein ligand, YL-IPA08, on alleviating inflammation-induced depression-like behavior in mice and investigated its mechanism of action. Mice were intracerebroventricularly injected with 1, 10, 100 or 1000 ng lipopolysaccharide. The tail-suspension test and the forced swimming test confirmed that 100 ng lipopolysaccharide induced depression-like behavior. A mouse model was then established by intraventricular injection of 100 ng lipopolysaccharide. On days 16-24 after model establishment, mice were intragastrically administered 3 mg/kg YL-IPA08 daily. Immunohistochemistry was used to determine BrdU and NeuN expression in the hippocampus. YL-IPA08 effectively reversed the depression-like behavior of lipopolysaccharide-treated mice, restored body mass, increased the number of BrdU-positive cells, and the number and proportion of BrdU and NeuN double-positive cells. These findings indicate that YL-IPA08 can attenuate lipopolysaccharide-induced depression-like behavior in mice by promoting the formation of hippocampal neurons.

关键词： nerve regeneration YL-IPA08 hippocampus dentate gyrus lipopolysaccharide neuroinflammation depression translocator protein neural regeneration

Simplified aminocoumarin analogues as anticancer agents:Amino isosteric replacement in the noviose moiety resulted in substantial enhancement of antiproliferative activity

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Chinese Chemical Letters 2013年第8期24卷 719-722页

作者： Ting Zhang Zheng Yan yun-feng li Nan Wang State Key Laboratory of Bioactive Substance and Function of Natural Medicine Beijing Key Laboratory of Active Substance Discovery and Drugability EvaluationInstitute of Materia MedicoPeking Union Medical College & Chinese Academy of Medical Sciences

Simplified aminocoumarin analogues,either noviosylated or simple basic heterocycle attached 3-amido-coumarin compounds,are known to be promising anticancer agents targeting the C-terminal ATP-binding site of *** this study,3＇-amino isosteric replacement in the noviose moiety of two known noviose containing Hsp90 C-terminal inhibitors was synthetically realized for the first *** vitro evaluation of these compounds suggested that the introduction of a basic amino group into the noviose subunit resulted in significant improvement of their cytotoxicities.

关键词： 3-Amino-3-deoxy-L-noviose Aminocoumarin analogues Cytotoxicity Hsp90 inhibitors

Effect of Slab Subsurface Microstructure Evolution on Transverse Cracking of Microalloyed Steel during Continuous Casting

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Journal of Iron and Steel Research International 2014年第8期21卷 737-744页

作者： yun-feng li Guang-hua WEN Ping TANG Jian-quan li Cheng-li XIANG College of Materials Science and Engineering Chongqing University Pangang Group Panzhihua Steel and Vanagium Co. Ltd.

As to the continuous casting process of low carbon microalloyed steel, subsurface microstructure evolution plays an important role in the slab surface cracking. In order to study the effect of the slab subsurface microstructure evolution on the transverse cracking, three different secondary cooling patterns （i. e. , mild cooling, strong cooling and controlled cooling） were performed in the corresponding slab curved continuous caster. Based on the metallo- graphic results, three transformation regions were found to be formed with the evolution of microstructures at different depths in the slab subsurface. The three regions are strong cooling transformation （SCT） region, double phase transformation （DPT） region and mild cooling transformation （MCT） region, respectively. Meanwhile, it was also found that the crack index used for evaluating slab surface cracking susceptibility was decreased when the range of the DPT region was increased. This can be explained by the fact that the double phase transformation （austenite-ferrite-austenite） occurred resulting from thermal cycling in DPT region, which resulted in promoting the refinement of prior austenite grains and inhibiting the precipitation of film-like ferrite and chain-like precipitates. Under the con- trolled cooling pattern, the widely-distributed DPT region was formed in the range of 3.5--8.0 mm to the slab surface. And compared with other cooling patterns, the cracking susceptibility is lowest with a crack index of 0.4.

关键词： continuous casting microalloyed steel surface transversal cracking microstructure evolution cooling pattern