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Thixo-forging and simulation of complex parts of aluminum alloy AlSi7Mg

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International Journal of Minerals,Metallurgy and Materials 2010年第1期17卷 53-57页

作者： kai-kun wang School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

In order to investigate the formability of metal material in semisolid state, a series of experiments were carried out by thixo-forging the complex part of aluminum alloy AlSi7Mg. Through changing the upper punch, aluminum parts with different upper-cup dimensions can be successfully produced. The numerical simulation was conducted for investigating the forming limits of AlSi7Mg during thixo-forging. It is found that the simulation result is in good agreement with the experiment one.

关键词： thixo forging aluminum alloy formability numerical simulation

Formation of spheroidal microstructure of semisolid Al-Zn-Mg-Cu alloy prepared by RAP and modified SIMA

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稀有金属:英文版 2023年第9期42卷 3150-3160页

作者： Jin-Long Fu kai-kun wang School of Materials Science and Engineering University of Science and Technology BeijingBeijing100083China

The aim of this paper is to characterize the evolution of fine and spheroidal microstructure of Al-Zn-Mg-Cu alloy by strain-induced melting activation(SIMA)and recrystallization and partial remelting(RAP) *** phase transformation and microstructural evolution were investigated during the isothermal treatment in a wide semisolid temperature range from 550 to 610.C. Effects of isothermal temperatures and processing routes on coarsening rate constant were also analyzed. The results show that during the semisolid isothermal treatment, recrystallization process occurred and intermetallic particles were gradually dissolved into the liquid matrix once the heating temperature was above the solidus. Further extension of soaking time led to the coarsening and spheroidization of the solid grains. The increase in the soaking temperatures raised the liquid fraction and accelerated the spheroidization process. Smaller spheroidal grains and better spheroidization effect were obtained in SIMA microstructure in comparison to RAP microstructure. The coarsening rate constants were, respectively, 319 and 454 μm^(3)·s^(-1) in SIMA samples after soaked at 600 and 610.C. The coarsening rate constants of 349 and 522 μm^(3)·s^(-1) were achieved in RAP microstructure.

关键词： Aluminum alloy Isothermal soaking Microstructural evolution Phase transformation Coarsening

Optimization of ECAP-RAP process for preparing semisolid billet of 6061 aluminum alloy

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International Journal of Minerals,Metallurgy and Materials 2020年第6期27卷 792-800页

作者： Zu-jian Yang kai-kun wang Yan Yang School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China State Key Laboratory of Nickel and Cobalt Resources Comprehensive Utilization Jinchang 737100China

6061 aluminum alloy semisolid billet was prepared by the equal-channel angular processing(ECAP)-recrystallization and partial(RAP)process(a combination of equal-channel angular processing and recrystallization and partial remelting).The effects of different process parameters on the alloy microstructure were studied and the quantitative relationship between the process parameters and microstructure was established by response surface methodology(RSM)to optimize the process *** to the orthogonal test,the holding temperature and holding time of the four ECAP-RAP process parameters were found to have the greatest impact on the microstructural characteristics,including average grain size and average shape *** RSM,it was also found that when the average grain size or the average shape factor is optimized separately,another will be *** the two indexes were simultaneously considered,the optimal process parameters were found to be a holding temperature of 623°C and holding time of 13 min,and the corresponding average grain size and average shape factor were 35.97μm and 0.8535,***,comparing the experimental and predicted values,the reliability of the established response surface model was verified.

关键词： 6061 aluminum alloy equal-channel angular pressing semisolid microstructure response surface methodology

Influence of Processing Parameters on Microstructural Evolution and Tensile Properties for 7075 Al Alloy Prepared by an ECAP-Based SIMA Process

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Acta Metallurgica Sinica(English Letters) 2018年第4期31卷 337-350页

作者： Jin-Long Fu Hong-Jun Jiang kai-kun wang School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China Wuxi Turbine Blade Co. LtdWuxi 214174JiangsuChina

A modified strain-induced melt activation（SIMA）process consisting of homogenization,equal-channel angular pressing（ECAP）and subsequent heating to the semisolid temperatures was introduced to prepare the 7075 aluminum alloy with superior thixotropic *** effects of both the homogenization and the number of ECAP passes,as well as the isothermal temperatures on the microstructural evolution,were *** results indicate that ideal microstructure wherein fine and globular solid grains surrounded by uniform liquid films can be achieved through ECAP deformation-recrystallization *** the number of ECAP passes accelerates the recrystallization of strained grains,thus reducing the average grain size and improving the grain ***,higher holding temperatures and prolonged soaking time can improve the growth of the solid *** main coarsening mechanisms,*** and Ostwald ripening,contribute to the growth of the solid grains simultaneously and *** tensile strength of the 7075 alloys after four-pass ECAP-based SIMA and T6 heat treatment is relatively lower than the as-received billet,while the elongation of SIMA processed samples is much higher than that of as-received *** the number of ECAP passes improves the tensile strength for alloys with and without T6 treatment due to the fine grain strengthening mechanism.

关键词： Semisolid Aluminum Equal-channel angular pressing Mierostructural evolution Tensileproperty

Experiment and Simulation for Rolling of Diamond–Cu Composites

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Acta Metallurgica Sinica(English Letters) 2017年第8期30卷 791-800页

作者： Yun-Long wang kai-kun wang Yu-Wei wang Guang-Chen Li School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China Department of Engineering University of LeicesterUniversity Road Leicester LE1 7RH UK Tianjin Xiangtong Electronic Company LTD Tianjin 301800 China

We demonstrate an innovative preparation approach of diamond/Cu composites by powder-in-tube technique and rolling. A small copper tube was loaded with Ti- and Cu-coated diamond particles, mad then the diamond particles were combined with Cu matrix by composite rolling. The morphology and element distribution of the interface between diamond and Cu were determined by scanning electron microscopy and energy-dispersive spectrometer. Finite element method （FEM） simulation was used to analyze the rolling process associated with experiment by DEFORM-3D. The final experimental results showed that homogeneous distribution of diamond particles could be observed in the center layer of the composites. According to the contrast experiments, the sample, whose diamond particle size is 0.12-0.15 mm and thickness of pre-rolling is 1.2 mm, showed relatively complete morphologies and homogeneous distribution. Experimental results indicated a poor efficacy of excessive rolling reduction. The thermal conductivity of the composites is about 453 W （m K）-1 by theoretical calculation. For FEM simulation, roiling strain and temperature field of the composites were simulated by DEFORM-3D. Simulation results were interpreted, and numerical results verified the reliability of the model. The simulation predicted that the local area of large strain, indicative of the strain along the thickness direction, could be intensified by adding diamond particles.

关键词： Diamond/Cu composites Powder-in-tube technique (PIT) Rolling Finite element method(FEM) simulation

Microstructure evolution and thixoforming behavior of 7075 aluminum alloy in the semi-solid state prepared by RAP method

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International Journal of Minerals,Metallurgy and Materials 2016年第12期23卷 1404-1415页

作者： Jin-long Fu kai-kun wang Xiao-wei Li Hai-kuan Zhang School of Materials Science and Engineering University of Science and Technology Beijing Tianjin Zhonglian Precision Casting Co. Ltd.

The effects of isothermal treatments on the microstructural evolution and coarsening rate of semi-solid 7075 aluminum alloy produced via the recrystallization and partial remelting （RAP） process were investigated. Samples of 7075 aluminum alloy were subjected to cold extrusion, and semi-solid treatment was carried out for 5-30 min at temperatures ranging from 580 to 605℃. A backward-extrusion experiment was conducted to investigate liquid segregation during the thixoforming process. The results revealed that obvious grain coarsening and spheroidization occurred during prolonged isothermal treatments. In addition, higher soaking temperatures promoted the spheroidization and coarsening process because of the increased liquid fraction and the melting of second phases. Segregation of the liquid phase caused by the difference in fluidity between the liquid and the solid phases was observed in different regions of the thixoformed specimens.

关键词： aluminum alloys microstructural evolution thixoforming grain coarsening segregation

Effect of Ti_(p) Content on the Work Hardening and Softening Behavior of Mg-Zn-Ca Alloy

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Acta Metallurgica Sinica(English Letters) 2024年第3期37卷 551-560页

作者： Jin-kai Zhang Cui-Ju wang Yi-Dan Fan Chao Xu kai-Bo Nie kun-kun Deng Shanxi Key Laboratory of Advanced Magnesium-Based Materials College of Materials Science and EngineeringTaiyuan University of TechnologyTaiyuan 030024China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China

The Ti_(p)/ZX60 composites with different Ti_(p) contents were prepared by semi-solid stirring *** extrusion,the microstructure,work hardening and softening behavior of the Ti_(p)/ZX60 composites were analyzed compared with the ZX60(Mg-6Zn-0.2Ca)*** results showed that the addition of Ti_(p) could not only promote the nucleation of dynamic recrystallized(DRXed)grains,but also be propitious to the refinement of DRXed *** increasing Ti_(p) content,the size of DRXed grains decreased accompanied with increasing volume fraction of DRXed *** the Ti_(p) content increased to 15 vol.%,the average size and volume fraction of DRXed grains reached to~0.32μm and 93.2%,***,both the strength and elongation were improved by the addition of Ti_(p).With increasing content of Ti_(p),a substantial increase in the strength was achieved with little change in the ***,the elongation decreased sharply when the Ti_(p) content further increased to 15 vol.%.The addition of Ti_(p) led to an increase in the work hardening rate,which gradually increased with increasing Ti_(p) ***,the softening rate did not demonstrate the same tendency with increasing Ti_(p) *** the conventional ceramic particles,the Ti_(p) can be deformed in coordination with the matrix alloy,which imparted a higher softening rate to the matrix *** though the softening rate improved as the Ti_(p) content increased from 5 to 10 vol.%,it dropped deeply as the Ti_(p) content increased to 15 vol.%owing to the fracture of Ti_(p) during extrusion.

关键词： Titanium particle content Particle reinforced magnesium matrix composites Work hardening Softening behavior Mechanical properties

Investigation on inductive heating of A356 alloy for thixo-forming

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International Journal of Minerals,Metallurgy and Materials 2009年第3期16卷 309-313页

作者： kai-kun wang Jian-lin Sun Yong-lin Kang Qi Zhang Lei Yang Chun-mei Ma School of Materials Science and Engineering University of Science and Technology Beijing 100083 Beijing China East-China Micro-electronic Institute of Technology 230022 Hefei China

To meet the demands of continuous stream-line for component production in the thixo-forming industry, billet heating should be of high quality and in a controllable way. A 4-step inductive heating strategy for aluminum alloy A356 was performed. Thixotropic testing and microstructure analysis showed that a homogenous temperature distribution was achieved after temperature-power-time optimization. Theoretical analysis was given concerning the thermal conductivity and heat capacity of A356 between conventional and semisolid casting microstructures. The experimental results show that the optimized 4-step strategy could be the best strategy for billet heating during the thixo-forming of aluminum alloy A356.

关键词： Thixo-forming aluminum alloys inductive heating temperature distribution

Microstructure and corrosion resistance of bone-implanted Mg-Zn-Ca-Sr alloy under different cooling methods

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Rare Metals 2021年第3期40卷 643-650页

作者： He-Ning Liu Kui Zhang Xing-Gang Li Yong-Jun Li Ming-Long Ma Guo-Liang Shi Jia-Wei Yuan kai-kun wang State Key Laboratory of Nonferrous Metals and Process GRINM Group Co.Ltd.Beijing 100088China School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China GRIMAT Engineering Institute Co. Ltd.Beijing 101407China General Research Institute for Nonferrous Metals Beijing 100088China

The cooling gradient of Mg-3 Zn-1 Ca-0.5 Sr alloy in cast ingots under different cooling methods(air cooling,warm-water cooling and ice-water-mixture cooling) was examined and the effect of cooling rate on the structure and corrosion properties was *** microstructure of the alloy was composed of α-Mg,Ca_(2) Mg_(6) Zn_(3) and Mg_(17)Sr_(2) *** the solidification cooling rate increased,the grain was refined,Zn and Sr were less segregated,the distributions of Zn and Sr were more uniform,and corrosion rate was found to first increase and then decrease;this contradicts the findings of recent *** cooling rate increasing,the number of corroded microcouples comprising second phase and α-Mg *** α-Mg participates in corrosion,leading to a layered and deep corrosion pit and an increased corrosion ***,as the microstructure became sufficiently dense,the corroded structure protected the deep α-Mg from participating in corrosion,thus reducing the corrosion rate.

关键词： Corrosion Mg-Zn-Ca-Sr Morphology Cooling methods