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Optimization of Processing Parameters for Laser Powder Deposition using Finite Element Method

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Journal of Wuhan University of Technology(Materials Science) 2010年第5期25卷 832-837页

作者：付垚 state key laboratory of non-ferrous metals and processes General Research Institute for Non-ferrous Metals

In order to investigate the effects of powder materials and processing parameters on thermal and stress field during laser powder deposition （LPD）, a finite element model was developed with the help of ANSYS software. The finite element model was verified by the comparison between the experimental results and computed results. Then LPD processes with different powder materials and processing parameters were simulated by using the FE model. The results show that less difference of thermal conductivity and thermal expansion coefficient between powder material and substrate material produces lower residual stress; higher laser power, laser scanning speed and smaller laser beam diameter can lead higher peak temperature and higher residual stress. The research opens up a way to rational selection of the powder materials and processing parameters for ensured quality.

关键词： laser powder deposition thermal field stress field powder material processing parameters

Hot workability of Mg-9Y-1MM-0.6Zr alloy

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Journal of Rare Earths 2011年第5期29卷 460-465页

作者：马鸣龙何兰强李兴刚李永军张奎 state key Lab of non-ferrous metals and processes General Research Institute for Non-Ferrous Metals

The behavior evolvement of Mg-9Y-1MM-0.6Zr （WE91） alloy during hot deformation process was discussed. The flow stress behavior of magnesium alloy over the strain rate range of 0.001 to 1 s–1 and the temperature range of 653 to 773 K was studied on a Gleeble-1500D hot simulator under the maximum deformation degree of 60%. The experimental results showed that the relationship between stress and strain was obviously affected by the strain rate and deformation temperature and the flow curves observed were typical of the occurrence of dynamic recrystallization. The flow stress of WE91 magnesium alloy during high temperature deformation could be represented by the Zener-Hollomon parameter in the hyperbolic Arrhenius-type equation. The average deformation activation energy Q and strain coefficient n were 224.11 kJ/mol and 3.08 by calculation,respectively. The processing maps were calculated and analyzed according to the dynamic materials model. The map at strain of 0.916 exhibited three domains with peak efficiency of 49%,44% and 42%,respectively. It was found that the alloy could be extruded at 693 K with mechanical properties of σ0.2=240 MPa,σb=315 MPa and δ=15.5%.

关键词： rare-earth magnesium alloy plastic behavior processing map microstructures

Effect of Rolling Parameters on Plate Curvature during Snake Rolling

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Journal of Wuhan University of Technology(Materials Science) 2012年第2期27卷 247-251页

作者：付垚 state key laboratory of non-ferrous metals and processes General Research Institute for Non-ferrous Metals

In order to predict the plate curvature during snake rolling, FE model was constructed based on plane strain assumption. The accuracy of the FE model was verified by the comparison between the plate curvature conducted by FE model and experiment respectively. By using FE model, the effect of offset distance, speed ratio, reduction, roll radius and initial plate thickness on the plate curvature during snake rolling was investigated. The experimental results show that, a proper offsetting distance can efficiently decrease plate curvature, however an excessive offsetting distance will increase plate curvature. A larger speed ratio, reduction will cause a large plate curvature, however a larger roll radius has effect to reduce plate curvature. Plate which undergoes a larger reduction and plate with a larger initial thickness always need a larger offset distance to keep the plate the minimum plate curvature, but for a larger roll radius a smaller offset distance is needed.

关键词： snake rolling plate curvature FE model offset distance

Effects of isothermal homogenization on microstructure evolution of Mg-7Gd-5Y-1MM-0.5Zr alloy

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Journal of Rare Earths 2015年第4期33卷 439-444页

作者：李蒙李兴刚张奎李永军马鸣龙石国梁袁家伟刘靖宝 state key laboratory for Fabrication and Processing of non-ferrous metals General Research Institute for Non-Ferrous Metals

Optical microscopy （OM）, scanning electronic microscopy （SEM） and X-ray diffraction （XRD） were performed to inves- tigate the influence of homogenization on the microstructures of the Mg-7Gd-5Y-1MM （Ce-rich RE）-0.5Zr magnesium alloy. The results indicated that α-Mg, Mg24（GdY）5 phase, Mg5（GdY） phase and Mg12MM phase coexisted together in as-cast alloy; the micro- structures were largely characterized by α-Mg matrix and gray globular or elliptic ball Mg12MM phase, in addition to those with cubic block Mg24（GdY）5 phase after homogenization; the reasonable homogenization regime was maintained at 530 ℃ for 32 h.

关键词： homogenization treatment magnesium microstructure evolution rare earths

Microstructural evolution of aluminum alloy 7B04 thick plate by various thermal treatments

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中国有色金属学会会刊：英文版 2008年第1期18卷 40-45页

作者：李志辉熊柏青张永安朱宝宏王锋刘红伟 state key laboratory for Fabrication and Processing of non-ferrous metals General Research Institute for Non-ferrous Metals

The microstructure of an AA 7B04 alloy in the form of plate was investigated using differential scanning calorimetry(DSC)and TEM analysis *** properties and electrical conductivity of AA 7B04 under various heat treatment conditions were also *** results reveal that peak-aged microstructure contains GP zones and η' precipitates *** retrogressing and reaging(RRA),the η' and η precipitates disperse in the alloy matrix,and the η precipitates distribute coarsely and sparsely,decorating the grain boundaries,together with precipitate free zones(PFZs)around *** is also shown that selecting of suitable heat treatments can provide optimal precipitates in matrix and at grain boundaries,which gives rise to a combination of high strength and stress corrosion cracking(SCC)resistance in such materials.

关键词：铝合金显微结构热处理金属学

Role of iron ore in enhancing gasification of iron coke:Structural evolution,influence mechanism and kinetic analysis

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International Journal of Minerals,Metallurgy and Materials 2025年第1期32卷 58-69页

作者： Jie Wang Wei Wang Xuheng Chen Junfang Bao Qiuyue Hao Heng Zheng Runsheng Xu School of Chemistry and Materials Science Hubei Engineering UniversityXiaogan 432000China key laboratory for ferrous Metallurgy and Resources Utilization of Ministry of Education Wuhan University of Science and TechnologyWuhan 430081China Institue of Ironmaking Technology Baosteel Central Research InstituteShanghai 201999China state key laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China

The utilization of iron coke provides a green pathway for low-carbon *** uncover the influence mechanism of iron ore on the behavior and kinetics of iron coke gasification,the effect of iron ore on the microstructure of iron coke was ***,a comparative study of the gasification reactions between iron coke and coke was conducted through non-isothermal thermogravimetric *** findings indicate that compared to coke,iron coke exhibits an augmentation in micropores and specific surface area,and the micropores further extend and *** provides more adsorption sites for CO_(2) molecules during the gasification process,resulting in a reduction in the initial gasification temperature of iron *** the heating rate in non-isothermal gasification can enhance the reactivity of iron *** metallic iron reduced from iron ore is embedded in the carbon matrix,reducing the orderliness of the carbon structure,which is primarily responsible for the heightened reactivity of the carbon *** kinetic study indicates that the random pore model can effectively represent the gasification process of iron coke due to its rich pore ***,as the proportion of iron ore increases,the activation energy for the carbon gasification gradually decreases,from 246.2 kJ/mol for coke to 192.5 kJ/mol for iron coke 15wt%.

关键词： low-carbon ironmaking iron coke gasification structural evolution kinetic model

Homogenization heat treatment of Mg-7.68Gd-4.88Y-1.32Nd-0.63Al-0.05Zr alloy

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Journal of Rare Earths 2014年第5期32卷 445-450页

作者：张国栋李兴刚马鸣龙李永军石国梁袁家伟张奎 state key laboratory for Fabrication and Processing of non-ferrous metals Beijing General Research Institute for Non-ferrous Metals

The microstructures and mechanical properties of the Mg-7.68Gd-4.88Y-1.32Nd-0.63A1-0.05Zr magnesium alloy were investigated both in the as-cast condition and after homogenization heat treatment from 535 to 555 ℃ in the time range 0-48 h by op- tical microscopy, scanning electron microscopy and hardness measurement. The as-cast alloy consisted of ct-Mg matrix, Mgs（Y0.5Gd0.5） phase which is a eutectic phase, strip of Al2（Y0.6Gd0.4） phase, little A13Zr and Mg（Y3Gd） phase. With the increasing of homogenization temperature and time, the Mgs（Y0.5Gd0.5） phase was completely dissolved into the matrix. The Al2（Y0.6Gd0.4） phase was almost not dissolved which impeded grain boundaries motion making the grain size almost not changed in the process of ho- mogenization. The optimum homogenization condition was 545 ℃/16 h. The tensile strength increased, yield strength decreased and the plasticity improved obviously after 545 ℃/16 h homogenization treatment.

关键词： Mg-Gd-Y-Nd-AI alloy homogenization second phase hardness rare earths

Identification of thermal effects involved in DSC experiment on Al-Cu-Mg-Ag alloys with high Cu:Mg ratio

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International Journal of Minerals,Metallurgy and Materials 2011年第6期18卷 671-675页

作者： Jian-bo Zhang Yong-an Zhang Bao-hong Zhu Feng Wang Zhi-hui Li Xi-wu Li Bai-qing Xiong state key laboratory of nonferrous metals and processes General Research Institute for Non-ferrous Metals Beijing 100088 China

Precipitation reactions in the differential scanning calorimetry （DSC） of an Al-Cu-Mg-Ag alloy were identified by analyzing the results from hardness test,electrical conductivity test,and transmission electron microscope （TEM） *** is discovered that thermal effects can be identified through selected area electron diffraction and bright-field *** reaction peaks around 171,231,and 276℃ can be attributed to a structural rearrangement of coherent zones,to the precipitation of Ω phases,and to the precipitation of Ω and θ＇ and possible combination with the transition of θ＇→θ,*** addition,the hardness and electrical conductivity of the alloy change proportionately with the progression of reactions during the heating *** phenomenon can be attributed to the evolution of the micro-structure.

关键词： aluminum alloys thermal effects identification differential scanning calorimetry microstructure

Hot Deformation Behavior and Processing Map of Spray Formed M3∶ 2 High Speed Steel

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Journal of Iron and Steel Research International 2016年第5期23卷 501-508页

作者： Lin LU Long-gang HOU Hua CUI Jin-feng HUANG Yong-an ZHANG Ji-shan ZHANG state key laboratory for Advanced metals and Materials University of Science and Technology Beijing state key laboratory of non-ferrous metals and Process General Research Institute for Non-ferrous Metals

Hot deformation behavior of a new type of M3∶ 2 high speed steel with niobium addition made by spray forming was investigated based on compression tests in the temperature range of 950-1 150 ℃ and strain rate of 0. 001-10 s^（-1）. A comprehensive constitutive equation was obtained,which could be used to predict the flow stress at different strains. Processing map was developed on the basis of the flow stress data using the principles of dynamic material model. The results showed that the flow curves were in fair agreement with the dynamic recrystallization model. The flow stresses,which were calculated by the comprehensive constitutive equation,agreed well with the test data at low strain rates（ ≤1 s^（-1））. The material constant（ α）,stress exponent（ n） and the hot deformation activation energy（ Q_（HW）） of the new steel were 0. 006 15 MPa^（-1）,4. 81 and 546 kJ·mol^（-1）,respectively. Analysis of the processing map with an observation of microstructures revealed that hot working processes of the steel could be carried out safely in the domain（ T = 1 050-1 150 ℃,ε = 0. 01- 0. 1 s^（-1））with about 33% peak efficiency of power dissipation（ η）. Cracks was expected in two domains at either lower temperatures（〈 1 000 ℃） or low strain rates（ 0. 001 s^（-1）） with different cracking mechanisms. Flow localization occurred when the strain rates exceeded 1 s^（-1） at all testing temperatures.

关键词： high speed steel spray forming hot deformation processing map niobium