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Continuous observation of twinning and dynamic recrystallization in ZM21 magnesium alloy tubes during locally heated dieless drawing

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Journal of Magnesium and Alloys 2022年第3期10卷 791-805页

作者： Peihua Du Shusaku Furusawa Tsuyoshi Furushima Department of Mechanical and Biofunctional Systems Institute of Industrial ScienceThe University of Tokyo4-6-1KomabaMeguroTokyo 153-8505Japan

Compared to cold drawing,dieless drawing has shown great potential for manufacturing biodegradable Mg alloy microtubes due to the large reduction in area acquired in a single pass.However,owing to the local heating and local deformation,the deformation mechanism during dieless drawing is not clear,and thus causing difficulties in controlling the microstructure of dieless drawn tubes.For the purpose of acquiring a desired microstructure.in this study the deformation mechanism of ZM21 Mg alloy tube was clarified by conducting continuous observation of the microstructural evolution during dieless drawing.The results show that both SRX and DRX occurred during dieless drawing.SRX occurred before the plastic deformation to soften dieless drawn tubes.With increase of feeding speed,the deformation mechanism changed accordingly:(1) At the low-speed of 0.02 mm/s,the deformation mechanism was dominated by twin-slip sliding,during which {10-12} tension twins were generated inside grains to accommodate the plastic deformation by changing the crystal orientation.(2) At the intermediate-speed of 2 mm/s,a twin-DRX process related to {10-12} tension twin was observed,which was characterized by the generation of abundant {10-12} tension twins and the evolution of misorientation angle of {10-12} tension twins.Moreover,the transformation from twin-DRX to CDRX can be observed at the late stage of plastic deformation,which was attributed to the inhomogeneous conditions of dieless drawing.(3) At the high-speed of 5 mm/s,a CDRX process was observed,during which grain boundary sliding and grain tilting were observed,in addition to the gradual rotation of subgrains.These results show that during dieless drawing,DRX is not only a temperature-dependent phenomenon,but also influenced by the variation of feeding speed.

关键词： dieless drawing Inhomogeneous condition Twining Dynamic recrystallization Microstructure evolution Magnesium alloy Twinning

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维普期刊数据库

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Processing limit maps for the stable deformation of dieless drawing

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International Journal of Minerals,Metallurgy and Materials 2011年第3期18卷 330-337页

作者： Yong He Xue-feng Liu Jian-xin Xie Hong-gang Zhang Key Laboratory for Advanced Materials Processing （MOE） University of Science and Technology Beijing Beijing 100083 China State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 China

Tin bronze wires were produced by dieless drawing. The effects of heating power, the distance between cooler and heater as well as feeding speed on the diameter, the temperature field, and the deformation region profile of the wires were investigated. The results indicated that each processing parameter exhibited both lower and upper limits of stable deformation based on the criterion of stable deformation with the diameter fluctuation of ±0.05 mm. Both the temperature and its gradient of the deformation region increased with increasing heating power under stable deformation, but decreased with an increase in feeding speed. As the distance between cooler and heater increased, the temperature of the deformation region increased and the slope of the deformation region profile decreased. The processing limit map of stable deformation exhibited a closed curve and the unstable deformation consisted of wire breakage and diameter fluctuations.

关键词： tin bronze wire dieless drawing processing parameters turning method

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维普期刊数据库

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A fractal-based model for the microstructure evolution of silicon bronze wires fabricated by dieless drawing

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International Journal of Minerals,Metallurgy and Materials 2010年第6期17卷 770-776页

作者： Zhen Wang Xue-feng Liu Yong He Jian-xin Xie Key Laboratory of the Ministry of Education of China for Advanced Processing Technology of Materials University of Science and Technology Beijing Beijing100083 China State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 China

The back-propagation neural （BPN） network was proposed to model the relationship between the parameters of the dieless draw- ing process and the microstrecmres of the QSi3-1 silicon bronze alloy. Combined with image processing techniques, grain sizes and grain-boundary morphologies were respectively determined by the quantitative metallographic method and the flactal theory. The outcomes obtained show that the deformed microstructures exhibit typical fractal features, and the boundaries can be characterized quantitatively by ffactal dimensions. With the temperature of 600-800℃ and the drawing speed of 0.67-1.00 mm-s-1, either a lower temperature or a higher speed will cause a smaller grain size together with an elevated fractal dimension. The developed model can be capable for forecasting the microstructure evolution with a minimum error. The average relative errors between the predicted results and the experimental values of grain size and fractal dimension are 3.9% and 0.9%, respectively.

关键词： silicon bronze dieless drawing microstructure fractal dimension neural networks

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Microstructure and performance of biodegradable magnesium alloy tubes fabricated by local-heating-assisted dieless drawing

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Journal of Magnesium and Alloys 2020年第3期8卷 614-623页

作者： Peihua Du Shusaku Furusawa Tsuyoshi Furushima Department of Mechanical and Biofunctional Systems Institute of Industrial ScienceThe University of Tokyo4-6-1KomabaMeguroTokyo 153-8505

Magnesium(Mg)alloy stents are expected to be the next generation of stents because of good biocompatibility and biodegradability.Compared with cold drawing,dieless drawing with local heating is an effective method for manufacturing the Mg alloy microtubes since a large reduction in area can be achieved in a single pass.However,the microstructure and properties of dieless drawn tubes have not been clarified,leading to the problems in practical application of dieless drawn tubes.In this study,the microstructure and performance of dieless drawn tubes are clarified.The results show that temperature and speed in the dieless drawing process are two factors in determining the grain size of dieless drawn tubes since decreasing the temperature or increasing the speed promotes the generation of fine-grained microstructure.Twins are also generated during the dieless drawing process,which 1)disintegrates grains leading to refinement and 2)causes Hall-Petch law effect on dieless drawn tubes.Tensile tests show that grain size is the main factor in determining the mechanical properties of dieless drawn tubes,namely,0.2%proof stress 135-180MPa,ultimate tensile strength(UTS)200-250MPa,and elongation 8-12%.In 0.9 wt%NaCl solution,localized corrosion is the key factor in initiating the corrosion of dieless drawn tubes,but refined grains and fewer twins can alleviate local corrosion.These results imply that dieless drawn tubes are promising in the clinical application of Mg alloy stents for cardiovascular disease.

关键词： dieless drawing Magnesium alloy tube Microstructure Mechanical properties Corrosion properties

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维普期刊数据库

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Research on dieless drawing Process of Stainless Steel Tapered Tube

Research on Dieless Drawing Process of Stainless Steel Taper...

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中国材料大会2012

作者： Xuefeng Liu Ye Zhang Fang Qin Haoen Mao Jianxin Xie Key Laboratory for Advanced Materials Processing(MOE) University of Science and Technology Beijing Schaeffler Trading(Shanghai)Corporation Limited School of Materials Science and Engineering Hebei University of Science and Technology

ISBN: (纸本)9783037856093

The traditional forming technologies of stainless steel tapered tube have some disadvantages,such as its complicated processes,few product specification,low production efficiency and high production cost.dieless drawing is a new kind of near net-shaping process for fabricating tapered metallic tubes with large deformation per pass,high yield ratio of material and flexible production.dieless drawing of stainless steel tapered tube was studied systematically in order to establish both temperature field model with respect to the changes of boundary condition and metal flow velocity during deformation,and a drawing speed controlling model with respect to the volume change of deformation zone.The models were verified by experiments in the present investigation.Finally,a continuous pickling process with variable-speed was proposed for tapered metallic tube,which was successfully applied to surface oxidation film removal of the stainless steel tapered tube.

关键词： Tapered tube Stainless steel Forming technology dieless drawing

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A Novel Technology for Microwave Heated Wire drawing Process

A Novel Technology for Microwave Heated Wire Drawing Process

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先进纺织材料及加工技术国际学术会议

作者： Bo Keun Ha Jong Sung Kim You Huh Dept. of Mechanical Eng. Graduate School Kyung Hee University Laboratory of Intelligent Process and Control Kyung Hee University Faculty of Mechanical and Industrial System Engineering Kyung Hee University

Recent growth of modern industry requires multi-functional inorganic and micron-sized fibers. In this study, we suggested a novel method that could offer a high-efficient dieless drawing technology for manufacturing thin metal fibers based on the hot working principle. Microwave was used as the heat source. Experimental trials on a laboratory rig showed that the new system worked effectively and provided the feasibility in realizing the diameter attenuation up to 20 % diameter reduction. The theoretical model describing the wire deformation behavior in the working zone turned out to be in a good accordance to the experiment partly. Discrepancy in the hot zone near the exit could be attributed to the heat loss in the heat chamber. The coefficient of variation of the drawn wire diameter increased, as the draw ratio increased, which indicated that an ironing step would be needed to improve the evenness of the wire diameter.

关键词： Microwave Hot zone Metal wire dieless drawing Draw ratio Diameter reduction Coefficient of variation

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