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Characterization of Fe_3Si-based coatings on low silicon steel by pulsed Nd:YAG laser cladding

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International Journal of Minerals,Metallurgy and Materials 2009年第2期16卷 208-214页

作者： Dan-yang Dong chang-sheng liu Sui-yuan Chen Bin Zhang Key Laboratory for Anisotropy and Texture of Materials of the Ministry of Education of China Northeastern University Shenyang 110004 China School of Science College Northeastern University Shenyang 110004 China

The Fe3Si based coating was produced on the Fe-1 Si steel surface by a pulsed Nd：YAG （yttrium aluminum garnet） laser. Its phase constitution and microstructure were characterized by using X-ray diffraction （XRD）, optical microscope （OM）, and field emission scanning electron microscope （FESEM） with associated energy dispersive spectroscopy （EDS） and transmission electron microscopy （TEM）. The hyperfine structure of the coating was studied by Mrssbauer spectra （MS） and the magnetic property was also measured at room temperature by a vibrating sample magnetometer （VSM）. The obtained coating is pore and crack-free with dense microstructure and high Si content. The metallurgical bonding between the coating and the substrate was realized. The microstructure of the coating is typical fine dendrites. The major phase was confirmed by XRD and TEM to be the ordering D03 structured Fe3Si phase. In addition, there were smaller amounts of the Fe5Si3 phase and the γ-Fe phase in the coating. Compared with the substrate, the laser cladding coating has a lower saturation magnetization and a higher coercive force. The poor magnetic property might be because of rapid solidification microstructure and phase constitution in the coating.

关键词： silicon steel laser cladding hyperfine structure magnetic property

Effect of Temperature on Microstructure and Formability of Al-10 mass% Si Coatings

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Journal of Iron and Steel Research International 2016年第3期23卷 270-275页

作者： Jie ZHANG She-ming JIANG Qi-fu ZHANG chang-sheng liu National Engineering Laboratory Advanced Coating Technology for Metals Central Iron and Steel Research InstituteBeijing 100081China School of Materials and Metallurgy Northeastern UniversityShenyang 110004LiaoningChina

The type-1aluminized（Al-10mass% Si）coating on hot stamped steel is used in commercial *** effect of temperature on microstructure and formability of the Al-10mass% Si coating was ***-dip aluminized 22MnB5 steel was heated at 870,900,930,and 1 050 ℃ for 5 *** heat treatment at different temperatures,the microstructure of Al-10mass% Si was characterized by field-emission scanning electron microscopy and energy-dispersive *** results show that when the Al-10mass% Si coating was heated at 870℃for 5min,three types of intermetallic phases were formed：two ternary Fe-Si-Al phases（Fe2SiAl7＋Fe2Si2Al5and Fe2SiAl2＋Fe2Si2Al5）and one binary Fe-Al phase（FeAl3）.The phases in the coating became Fe2SiAl2＋Fe2Si2Al5and FeAl3,the binary Fe-Al phase near the interface became Fe2Al5 and the Si-rich layers were decreased with the increase of heating *** the heat treatment was 1 050℃for 5min,the Si-rich layer disappeared,the coating consisted of FeAl and Fe3 Al,and the Kirkendall voids were *** the heating temperature was increased through 870,900,and 930℃,the coating hardness was reduced and cracks were formed in the coating after hot *** formability of the coating with temperature change was confirmed by a hot stamping *** heated at 1 050 ℃,the coating was formable but continuous Kirkendall voids were observed.

关键词： Al-Si coating heating temperature microstructure formability hot-stamping

Fabrication of wear-resistant layers with lamellar eutectic structure by laser surface alloying using the in situ reaction between Cr and B_4C

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International Journal of Minerals,Metallurgy and Materials 2016年第11期23卷 1294-1301页

作者： You-zheng Sun Jin-bao Li Daniel Wellburn chang-sheng liu Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education) Northeastern University

To improve the wear resistance of Cr5 steel, wear-resistant layers with lamellar eutectic microstructure were fabricated by laser surface alloying（LSA）, which is dependent on the in situ reaction between Cr and B_4C. Our results indicated that the hypoeutectic structures of the LSA layers were divided into interdendritic eutectic structures and dendrites. The area fraction of the eutectic structures increased with increasing laser scanning speed, which improved the hardness and wear resistance of the LSA layers. The average hardness of the LSA layer prepared at a scanning speed of 8 mm/s was HV_（0.2） 883.9, which was 1.8 times greater than that of the traditional quenched layer（approximately HV 480）. After sliding for 659.4 m, the specimen prepared at a scanning speed of 8 mm/s exhibited a volume loss of 0.0323 mm^3, which was only 29.5% of the volume loss of the traditional quenched specimen.

关键词： eutectic wear resistance laser alloying hardness

Cavitation erosion behavior of WC coatings on CrNiMo stainless steel by laser alloying

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International Journal of Minerals,Metallurgy and Materials 2009年第2期16卷 203-207页

作者： Xiao-bin Zhang chang-sheng liu Xiao-dong liu Jiang Dong Bo Yu School of Materials and Metallurgy Northeastern University Shenyang 110004 China School of Material Science and Engineering Chongqing Institute of Technology Chongqing 400050 China Shenyang Research Institute of Foundry Shenyang 110022 China

The WC powder was precoated on the surface of CrNiMo stainless steel and then made into an alloying layer by using the laser alloying technique. Phases in the layers were investigated by X-ray diffraction （XRD） analysis and surface morphologies after cavitation erosion were observed with the help of scanning electron microscopy （SEM）. The cavitation erosion behavior of the CrNiMo stainless steel and WC laser alloying layer in distilled water was tested with the help of ultrasonic vibration cavitation erosion equipment. The results showed that the thickness of the laser alloying layer was about 0.13 mm. The layer had a dense microstructure, metallurgically bonded to the substrate, and no crack had been found. The cavitation erosion mass loss rate of the laser alloying layer was only 2/5 that of the CrNiMo stainless steel. The layer had better cavitation resistance properties because of its metallurgical combination and the strengthening effects of the precipitate phases.

关键词： martensite stainless steel laser surface alloying cavitation erosion WC

New Method for Evaluating Thermal Wear of Rolls in Rolling Process

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Journal of Iron and Steel Research International 2008年第6期15卷 52-55页

作者： LI chang-sheng liu Xiang-hua WANG Guo-dong State Key Laboratory of Rolling and Automation Northeastern University Shenyang 110004 Liaoning China

A new method was developed by a thermal wear machine to evaluate the thermal wear of roils in steel rolling process. The steel strip and rolls were simulated by upper and lower heating disks. The upper heating disk could he kept at a temperature of over 900 ℃ by induction heating. The pressure between the disks as high as 323.2 MPa could be achieved and the slipping rate could be 12. 7 %. The thermal wear of high speed steel （HSS） roll material, the wear rate of the HSS roll, and the SEM morphology of a worn HSS roll surface were investigated. This method was useful and could be employed to simulate friction and wear between strip and roll during the strip rolling process.

关键词： thermal wear roll friction strip rolling induction heating

Retrogression characteristics of a novel Al-Cu-Li-X alloy

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International Journal of Minerals,Metallurgy and Materials 2010年第5期17卷 624-628页

作者： Zhi-shan Yuan Zheng Lu Xiu-liang Wu You-hua Xie sheng-long Dai chang-sheng liu Grikin Advanced Materials Co. Ltd. General Research Institute for Non-Ferrous Metals Beijing 100088 China Beijing Institute of Aeronautical Materials Beijing 100095 China School of Materials ＆ Metallurgy Northeastern University Shenyang 110004 China

Retrogression characteristics of a novel Al-Cu-Li-X alloy of 2A97 were studied by hardness testing, transmission electron microscopy （TEM）, and differential scanning calorimetry （DSC）. The retrogression treatments of aging at 155°C for 12 h followed by aging at 220 and 240°C were chosen by determining the peak temperature of δ＇ precipitation at 230°C by DSC. The retrogression treatment at a lower temperature of 220°C causes the precipitation and coarsening of δ＇ and θ＇ phases in the matrix, resulting in an increase in hardness. Retrogression at a higher temperature of 240°C causes the dissolution and coarsening of δ＇ and θ＇ precipitates in the matrix and on the grain boundaries, resulting in a decrease in hardness. Microstructural changes upon retrogression including the appearance of equilibrium precipitates such as T1, T2, δ＇, and θ are confirmed by the selected area electron diffraction and the bright and dark field image analysis.

关键词： retrogression artificial aging aluminum-lithium alloy microstructure

Effect of Oxygen on Surface Properties and Drug Release Behavior of Plasma Polymer of n-Butyl Methacrylate

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Chinese Chemical Letters 2005年第12期16卷 1641-1644页

作者： Yuan YUAN chang sheng liu Yuan ZHANG Min YIN Jie XU Engineering Research Center for Biomedical Materials of Ministry of Education ECUST Center of Analysis and Research ECUST Shanghai 200237

The effects of oxygen on the chemical structure, morphology, hydrophilicity and drug release behavior of radio-frequency plasma poly n- butyl methacrylate （PPBMA） thin film were carded out for the first time. ATR-FTIR and XPS showed that oxygen had little influence on the chemical structure and composition of PPBMAs, which did not agree with the thought that the presence of oxygen gas would increase the oxidized carbon functionalities in the plasma polymer. SEM and static contact angle measurement indicated that in case of deposition with oxygen, the smoothness and hydrophilicity of PPBMA were dramatically improved. The drug release behavior showed that drug release from the PPBMA coating without oxygen was biphasic patterns, while from PPBMA coating with oxygen was Higuchi release. These results were helpful for the design and tailoring of the PPBMA polymer film and other of plasma polymers film, but could provide a new idea for the drug release controlled form.

关键词： Plasma n-butyl methacrylate polymer oxygen chemical structure morphology hydrophilicity

Model Algorithm Research on Cooling Path Control of Hot-rolled Dual-phase Steel

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Journal of Iron and Steel Research International 2016年第10期23卷 1028-1034页

作者： Xiao-qing XU Xiao-dong HAO Shi-guang ZHOU chang-sheng liu Qi-fu ZHANG School of Material Science and Engineering Northeastern University New Metallurgy Hi-tech Group Co. Ltd.

With the development of advanced high strength steel,especially for dual-phase steel,the model algorithm for cooling control after hot rolling has to achieve the targeted coiling temperature control at the location of downcoiler whilst maintaining the cooling path control based on strip microstructure along the whole cooling section.A cooling path control algorithm was proposed for the laminar cooling process as a solution to practical difficulties associated with the realization of the thermal cycle during cooling *** heat conduction equation coupled with the carbon diffusion equation with moving boundary was employed in order to simulate temperature change and phase transformation kinetics,making it possible to observe the temperature field and the phase fraction of the strip in real *** this basis,an optimization method was utilized for valve settings to ensure the minimum deviations between the predicted and actual cooling path of the strip,taking into account the constraints of the cooling equipment′s specific capacity,cooling line length,*** showed that the model algorithm was able to achieve the online cooling path control for dual-phase steel.

关键词： dual-phase steel laminar cooling phase transformation integrated process model cooling path control

Shape Setup System for 1700 Hot Strip Mill

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Journal of Iron and Steel Research International 2007年第5期14卷 27-30页

作者： GUO Zhong-feng XU Jian-zhong LI chang-sheng liu Xiang-hua State Key Laboratory of Rolling and Automation Northeastern University Shenyang 110004 Liaoning China

Shape setup （SSU） system is the core technology for hot strip mill （HSM）. A precise SSU system was used to improve the strip quality for HSM. The function of SSU, setup, and feedback was introduced. The main mathematical models of roll gap profile and longitudinal strain difference are set up. Strip profile allocation strategy was researched according to the SSU system of a domestic 1 700 mm HSM. The SSU system was put into practical use and the measurement results showed that strip flatness variation and strip profile variation could be controlled in target scope.

关键词： SSU hot strip mill, shape strip profile flatness