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Microstructural Evolution of pearlite in Eutectoid Fe-C Alloys during Severe Cold Rolling

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Journal of Materials Science & Technology 2005年第1期21卷 25-27页

作者： WantangFU YiXIONG JunZHAO YongLI T.Furuhara T.Maki KeyLab.ofMetastableMater.Sci.&Tech.YanshanUniversity Qiuhuangdao066004China//Dept.ofMater.Sci.andEng.KyotoUuiversityKyoto606-8501Japan KeyLab.ofMetastableMater.Sci.&Tech.YanshanUniversity Qiuhuangdao066004China Dept.ofMater.Sci.andEng. KyotoUuiversityKyoto606-8501Japan

The microstructural evolution of pearlite during severe cold rolling in Fe-0.8C binary alloy and Fe-1Mn-0.8C ternary alloys was investigated by using SEM, TEM and XRD etc. The results show that the deformed pearlite consists of irregularly bent lamella, coarse lamella with shear-band and fine lamella. As the rolling reduction increases, the proportion of fine lamella increases. The strong plastic deformation, amorphization and dissolution of cementite take place during the severe cold rolling. The maximum carbon content in ferrite reaches 0.15 mass% after 90% cold rolling.

关键词： pearlite Severe cold rolling Microstructural evolution Dissolution Amorphization Fe-C alloy

Stages and Fracture Mechanisms of Lamellar pearlite of 100-m-Long Differentially Hardened Rails Under Long-Term Operation Conditions

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Acta Metallurgica Sinica(English Letters) 2018年第12期31卷 1356-1360页

作者： A.A.Yuriev V.E.Gromov V.A.Grishunin Yu.F.Ivanov R.S.Qin A.P.Semin LTD Evraz-Integrated West Siberian MetallurgicalCombine NovokuznetskRussia Siberian State Industrial University NovokuznetskRussia National Research Tomsk Polytechnic University TomskRussia Institute of High Current Electronics SD RAS TomskRussia School of Engineering and Innovation The Open UniversityWalton HallMilton Keynes MK 7 6AAUK

Using the methods of transmission electron microscopy, the carbide phase evolution in surface layers of the differentiallyquenched rails is studied after the passed tonnage of 691.8 million tons at the depth up to 10 mm along the central axis andfillet of rail head. The action of two mutual supplement mechanisms of steel carbide phase transformation in surface layersat rail operation is established：（1） cutting mechanism of cementite particles with the following departure in the volume offerrite grains or plates （in pearlite structure）; （2） cutting mechanism and following dissolution of cementite particles,transfer of carbon atoms on dislocations （in Cottrell atmospheres and dislocation cores）, transfer of carbon atoms bymoving dislocations into ferrite grains volume （or plates） with the following repeated formation of nanosized cementiteparticles. The first mechanism is accompanied by the change in linear sizes and morphology of carbide particles. Cementiteelement composition change is not essential. Carbide structure change can take place during the second mechanism.

关键词： Cementite pearlite Fracture Rails Mechanisms Operation

Effects of Hot Deformation on the Evolution of Microstructure in Pearlitic Steel Wire Rod

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Acta Metallurgica Sinica(English Letters) 2023年第12期36卷 2058-2068页

作者： Zhendan Yang Xiao Zhang Chenhao Sang Pei Wang Dianzhong Li Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China

The influences of hot deformation parameters on pearlite grain nucleation and growth during austenite-pearlite phase transformation in a steel wire rod have been investigated through quantitative analysis of microstructure parameters such as austenite grain size,ferrite grain size,pearlite colony size,and lamellar spacing.During hot deformation,the austenite grain size decreases due to recrystallization,providing extra nucleation sites for pearlite phase transformation,which decreases the ferrite grain size and pearlite colony size.Moreover,the stored strain energy in undercooled austenite accelerates carbon diffusion during pearlite phase transformation,which facilitates ferrite grain growth and increases pearlite colony size.Consequently,the competing influence of recrystallization and strain energy provides flexibility in adjusting ferrite grain size and colony size by hot deformation.This study highlights the critical role of hot deformation in determining the microstructure of pearlitic steel.

关键词： pearlite Pearlitic phase transformation Hot deformation Microstructure Stored strain energy

Evolution of microstructures and mechanical properties with tempering temperature of a pearlitic quenched and tempered steel

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Journal of Iron and Steel Research(International) 2022年第9期29卷 1393-1403页

作者： De-zhen Yang Zhi-ping Xiong Chao Zhang Guan-zheng Feng Zhifang Cheng Xing-wang Cheng School of Materials Science and Engineering Beijing Institute of TechnologyBeijing 100081China National Key Laboratory of Science and Technology on Materials under Shock and Impact Beijing 100081China

Instead of conventional quenching and tempering,fast austenitization from an initial microstructure of lamellar pearlite followed by quenching and tempering was carried out,leading to the formation of inhomogeneous microstructure.It comprised different morphologies of lath martensite and retained austenite(RA).The effect of tempering temperature on microstructure evolution and tensile properties was systematically investigated.With increasing tempering temperature from 150 to 250℃,transition carbides gradually coarsened and their amount increased,the dislocation density in martensitic laths gradually decreased,and RA fraction decreased from 10.9%to 2.2%.The precipitation and dislocation strengthening can ensure a high strength,while RA can ensure a good ductility,leading to a simultaneous increase in the strength and ductility when decreasing tempering temperature.Specifically,the best combination of tensile properties(ultimate tensile strength of 2133±41 MPa and total elongation of 11.1%±1.3%)was achieved after tempering at 150℃.

关键词： Fast austenitization pearlite Tempering Manganese Mechanical property

Effect of Metallic, Nonmetallic, Water Cooled and Cryogenic Chills on pearlite Content (PC), Eutectic Cell Count (ECC) and Grain Size (GS) of Hypo Eutectic Nickel Alloyed Cast Iron

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Modeling and Numerical Simulation of Material Science 2017年第1期7卷 1-18页

作者： Joel Hemanth Mechanical Engineering H.M.S. Institute of Technology Tumkur India

This paper presents the results obtained, deductions made from solidification behaviour and a series of micro structural studies such as pearlite content, eu-tectic cell count and grain size of hypoeutectic gray cast iron which was sand cast (CO2 moulding) using metallic, nonmetallic, water cooled and subzero (cryogenic) end chills. Hypo-eutectic cast irons containing C 3.42, Si 2.4 and Ni 1.5 with impurity contents (S, P, Mn etc.) were solidified unidirectionally in an American Foundrymen Society (AFS) standard mould, the end of which was provided with different end chills to study the effect of chilling during solidifi-cation. The melts were inoculated with 0.3% Fe-Si to promote graphitization. It was observed that the transition from one structure to another is more gradual than normally obtained in the structure of cast irons solidified mul-ti-directionally in a sand mould at room temperature. Austenite dendrite interactions were shown to be a major factor in determining the microstructure, in which the higher dendrite reaction leads to changes in DAS, ECC and GS. It is observed that, the number of eutectic cells is an index of graphite nucleation and the effect of these on structure, since the eutectic cells are developed on the graphite nuclei during solidification.

关键词： Cast Iron Chill Solidification pearlite Eutectic and Grain Size

Parameters Optimization of Low Carbon Low Alloy Steel Annealing Process

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Acta Metallurgica Sinica(English Letters) 2013年第2期26卷 122-130页

作者： Maoyu ZHAO Qianwang CHEN School of Chemistry and Materials Science University of Science and Technology of China Department of Mechanical Engineering Hefei University

A suitable match of annealing process parameters is critical for obtaining the fine microstructure of material. Low carbon low alloy steel （20CrMnTi） was heated for various durations near Ac temperature to obtain fine pearlite and ferrite grains. Annealing temperature and time were used as independent variables, and material property data were acquired by orthogonal experiment design under intercritical process followed by subcritical annealing process （IPSAP）. The weights of plasticity （hardness, yield strength, section shrinkage and elongation） of annealed material were calculated by analytic hierarchy process, and then the process parameters were optimized by the grey theory system. The results observed by SEM images show that microstructure of optimization annealing material are consisted of smaller lamellar pearlites （ferrite-cementite） and refining ferrites which distribute uniformly. Morphologies on tension fracture surface of optimized annealing material indicate that the numbers of dimple fracture show more finer toughness obviously comparing with other annealing materials. Moreover, the yield strength value of optimization annealing material decreases apparently by tensile test. Thus, the new optimized strategy is accurate and feasible.

关键词： Annealing Process parameters pearlite Grey system Optimization

Molybdenum alloying in cast iron and steel

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Advances in Manufacturing 2020年第1期8卷 3-14页

作者： Xiang-Ru Chen Qi-Jie Zhai Han Dong Bao-Hua Dai Hardy Mohrbacher School of Materials Science and Engineering Shanghai UniversityShanghai 200444P.R.China CITIC Machinery Manufacturing Inc. Houma 043011ShanxiP.R.China Department of Materials Engineering KU LeuvenLeuven 3001Belgium NiobelCon bvba Schilde 2970Belgium

Metal casting is an important manufacturing technology for efficiently producing massive components with complex shape.A large share of industrial castings is made from iron and steel alloys,combining attractive properties and low production cost.Upgrading of properties in cast iron and steel is mainly achieved by alloying and in fewer cases by heat treatment.Molybdenum is an important alloying element in that respect,increasing strength,hardness and toughness.It also facilitates particular heat treatments such as austempering.The paper describes the metallurgical functionality of molybdenum alloying in iron-based castings and demonstrates its effectiveness for applications in the automotive and mining industry.

关键词： Grey cast iron Nodular iron pearlite Austempering Creep resistance Wear resistant alloys Hardness Toughness Mining industry Automotive industry

Modification of Corrosion Resistance of the Plain Carbon Steels by Pulsed Electric Current

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Acta Metallurgica Sinica(English Letters) 2018年第12期31卷 1233-1239页

作者： Jun-Yang Gao Xue-Bing Liu Hai-Fei Zhou Xin-Fang Zhang School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083China Zhejiang Electric Power Corporation Research Institute Hangzhou 310014China

The fracture of pipelines caused by corrosion cracks and the resulting oil and gas leakage can lead to great environmentalpollution and economic losses. These negative effects are due to serious corrosion of the plain carbon steels used for armorof flexible pipe in oil and gas transmission medium. However, corrosion resistance of carbon steel armors has yet to beimproved. In this study, the relationship between corrosion resistance and pearlite fraction in the plain carbon steels hasbeen investigated through the application of pulsed electric current. Based on immersion test and electrochemical mea-surement, pulsed electric current increases the corrosion resistance of the plain carbon steels by reducing the fraction ofpearlite phase. Pitting corrosion, which tends to initiate by galvanic corrosion of ferrite and cementite, is therefore inhibiteddue to the decrease in pearlite fraction （mixture of ferrite and cementite） under electropulsing.

关键词： Corrosion resistance pearlite Pulsed electric current Plain carbon steel

Orientation Relationships between Ferrite and Cementite by Edge-to-edge Matching Principle

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Journal of Materials Science & Technology 2011年第5期27卷 475-480页

作者： Ning Zhong Xiaodong Wang Zhenghong Guo Yonghua Rong Institute of Marine Materials Science and Engineering Shanghai Maritime University Shanghai 201306 China School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai 200240 China

The crystallographic features of pearlite were investigated by experiments and edge-to-edge matching principle. Two new orientation relationships between ferrite and cementite were determinated by selected area electron diffraction and then explained by our modified edge-to-edge matching method. The consistence of the experimental results with theoretical prediction confirms the practicability of the modified edge-to-edge matching model.

关键词： Orientation relationship pearlite Edge-to-edge matching Transmission electronmicroscopy