镁合金挤压预成形坯模压近终成型工艺研究
详细信息    本馆镜像全文|  推荐本文 |  |   获取CNKI官网全文
摘要
面对常规锻造成形工艺生产镁合金锻件所存在的工艺冗长、变形不均匀、材料利用率低、无性价比优势,难以实现规模生产应用的现实,本论文在“镁合金复合成形方法”专利的基础上,通过试验、数值模拟和理论分析相结合的方法,进行了“镁合金挤压预成形坯模压近终成型工艺”研究,以期为高品质镁合金锻件的低成本生产奠定技术基础。
     为此,本研究以拉伸试样为对象,先挤压生产具有试样二维几何特征的预成形挤压型材,然后根据试样厚度截取一段挤压型材,一次热模压获得几何形状、尺寸和表面质量满足要求的近终成型拉伸试样锻件。通过对该过程中材料的组织特征、拉伸性能、试样工艺品质、成形工艺技术指标等进行分析和检测,系统考核了该工艺的技术经济特征。
     研究表明:镁合金挤锻复合成型方法与常规锻压成型相比,具有以下特点:①短流程、高效率:将常规锻造工艺生产镁合金构件所经历的挤压开坯、多道次加热锻压和切边,缩短为一次挤压预成形后一次模压成型,大幅度缩短了工艺流程,提高了生产效率;
     ②低能耗:挤锻复合工艺实现了一次加热模压近终成型,减少了加热、锻造道次,并省略了切边,在简化锻造工艺的同时,降低了生产能耗;
     ③高材料收得率:因采用一次等体积封闭模压成形,基本消除了工艺废料,锻造工艺收得率达到95%、综合工艺收得率达85%以上,远高于常规锻造的30%~60%;
     ④变形组织、性能分布均匀:和常规锻件因锻造变形分布不均导致组织均匀性较差不同,挤锻复合工艺因采用大挤压变形率,在挤压预成形坯内获得了均匀细小的等轴细晶组织,模压成型后组织晶粒度和均匀性得到了有效保证,故工件内部组织、性能均匀。
     综上所述,和常规锻造工艺相比,挤锻复合近终成型工艺具有显著的技术经济优势。作为研究总结,本文还确定了“挤锻复合构件生产工艺开发路线”、提出了“挤锻复合工艺及最佳参数组合”,为该工艺的应用奠定了基础。
     挤锻复合构件生产工艺开发路线:锻件图→锻坯工艺数字分析→模压工艺优化→挤压预成形坯截面设计→挤压工艺及模具设计→铸坯设计
     挤锻复合工艺最佳参数组合:
     铸坯均质化工艺:入炉加热到400℃后保温4个小时;
     挤压预成形工艺:变形率≥16%,挤压模具预热温度400℃;
     模压坯截取工艺:余量~3%,在挤压预成形坯型材上截取模压坯料;
     挤压预成形坯段模压工艺:坯料入炉加热到400℃后保温30分钟,迅
     速移入400℃模具中以100~1000 mm/min的速度等温模压。
The present forge forming is characterized by its lengthy process, deformation non-uniformity, low material utilization ratio and high processing cost, and is therefore hard to be used to produce Mg forging parts for mass commercial application. To explore a new cost effective, high efficiency process with potential of stable offering quality products, based on a patented technique, the present study is devoted to do systematic research on“Near-net-shape Hot-pressing of Mg Extruded Preform”via experiments, numerical virtual reality and theoretical analysis.
     Aiming to produce tensile specimens with the technique, a preform extrusion profile with the 2D geometrical feature of the specimens was first produced. Then, the profile was sectioned, and net-shapely forged into the specimens with the required geometry and surface quality. Finally, the microstructure, tensile properties, processing quality, and processing parameters were empirically determined. Meanwhile, the technical and economic characteristics of the process are also examined in this paper.
     The obtained results show that, as compared with conventional forging forming process, the new process has the following characteristics:
     ①Short and efficient: The new process replace the multiple forging followed by trimming with one shot close-die press forming, which consequently reduces the process sequence and increases the processing efficiency or productivity.
     ②Low energy consumption: the new process reduces the multiple heating and forging in a conventional forge forming process to one-shot net-shape pressing of the extruded preform, which, in turn, largely reduces the energy consumption besides the processing simplification.
     ③High material utilization ratio: the one-shot close-die pressing almost eliminates the need for residual material. Consequently, the material utilization ratio in press forming is as high as more than 95%, and the comprehensive material utilization ratio from extrusion to press remains more than 85%, far higher than 30~60% for the conventional forge forming process.
     ④Uniform microstructure and properties: the employment of high deformation rate of≥16% during extrusion preforming ensure the obtainment of affine and equiaxed grains throughout the preform, which ensures a fine, equiaxial grains and the consequently good and uniform properties in the products.
     The results detailed above indicate that the newly developed process is obviously technically and economically advantageous as compared with the conventional forge forming process. As a summary, flow-chart of processing design for a Mg part and the optimal processing parameters of the new process were proposed as well to lay a sound base for its industrialization.
     The proposed flow-chart of processing design is: forged part drawing→forging numerical analysis→forging optimization→cross-section design of the extruded preform (profile)→design of extrusion die→design of casting billet.
     The optimized processing parameters for the new process are:
     The billet homogenization: heating at 400℃for 4 hours;
     Extrusion: deformation rate≥16%, die preheating temperature 400℃;
     Preform Sectioning: extruded profile sectioning for close die pressing with weight allowance less than 3%
     Close-die pressing: profile sections heated to 400℃for 30 minutes and, then, quickly removed into the die preheated to 400℃and forged with ram speed of 100~1000 mm/min.
引文
[1] B.L. Mordike, T. Ebert. Magnesium properties-applications-potential[J]. Materials Science and Technology. 2001, 302: 37-45.
    [2]张珣.镁合金产业的现状与发展[J].世界有色金属, 2002, 9:10-13.
    [3]王渠东,丁文江.镁合金开发现状与展望[J].世界有色金属, 2004, 7:8-11.
    [4] H. Friedrich, S. Schumann. Research for a“new age of magnesium”in the automotive industry [J]. Journal of Materials Processing Technology. 2001, 117:276-281.
    [5]曾小勤,王渠东,吕宜振,丁文江,朱燕萍.镁合金应用新进展[J].铸造, 1998,11:39-42.
    [6]钟皓,刘培英,周铁涛.镁及镁合金在航空航天中的应用及前景[J].航空工程与维修, 2002,4:41-42.
    [7]何良菊,李培杰.中国镁工业现状与镁合金开发技术[J].铸造技术, 2003, 24(3):161-162.
    [8]高仑.镁合金成形技术的开发与应用[J].轻合金加工技术, 2004, 32 (3):5-12.
    [9]刘金海,李国禄,刘根生.镁合金成形工艺及应用研究进展[J].轻合金加工技术, 2001, 29(8): 1-4.
    [10]吕宜振,瞿春泉,王渠东等.压铸镁合金现状及发展趋势[J].铸造, 1998,12:50-53.
    [11]刘环,周荣,蒋业华,卢德宏.镁合金成形技术及应用[J].昆明理工大学学报, 2002, 12(6):60-64.
    [12]余琨,黎文献,王日初,马正青.变形镁合金的研究、开发及应用[J].中国有色金属学报, 2003, 13(2):277-288.
    [13]吉泽升.日本镁合金研究进展及新技术[J].中国有色金属学报, 2003, 14(12):1977-1983.
    [14] Haferkamp H,Niemeyer M,Boehm R. Development processing and application range of Mg-Lialloy [J]. Mater Sci Forum. 2000, 350:31-42.
    [15] Aida T,Hatta H,Ramesh C. Workability and mechanical properties of lighter-than-water Mg-Li alloy [A]. Proc of the 3rd Inter Magnesium Confer Manchester[C]. Manchester 1996:143-153.
    [16] Das S K,Chang C F. Magnesium Alloys and their Applications [M]. Oberursel,FRG. DGM Information sgesellschaft.1992:487.
    [17] Towle D J, Friend C M. Comparison of compressive and tensile properties of magnesium based metal matrix composites [J]. Mater Sci Tech. 1993(3):35-40.
    [18] E.Aghion, B.Bronfin, D,Eliezer. The role of the magnesium industry in protecting the environment [J]. Journal of Materials Processing Technology. 2001, 117:381-385.
    [19]陈振华.变形镁合金[M].化学工业出版社, 2004,7(1):4-5.
    [20]黄少东,唐全波,赵祖德,刘川林,曹洋,赵军.用镁合金促进兵器装备轻量化[J].金属成形工艺, 2002, 20(5):8-10.
    [21] Minghetti T, Steinhoff K, Nastran M, Kuzman K. Advanced forming techniques for magnesium alloys [J]. Metallurgia Italiana. 2002, 94:19-23.
    [22] H Friedrich,S Schumann. Research for a“New age of magnesium”in the automotive industry [J]. Journal of Material Processing Technology. 2002, 117(3):276-281.
    [23]张士宏,许沂,王忠堂等.镁合金成形加工技术[J].世界科技研究与发展, 2001, 23(6):18-21.
    [24] N Ogawa, M Shiomi,K Osakada. Forming limit of magnesium alloy at elevated temperature for precision forging [J]. Int.J.Machine Tools and Manufacture. 2002,42:607-614.
    [25] J Enss, T Evertz,T Reier,et al. New magnesium rolled productions for automobile applications[A]. Proceedings of the Second Israeli International Conference on Magnesium Science&Technology[C]. DeadSea,Israel. 2000:19-34.
    [26] Anon. Precision forging of magnesium wrought alloys [J]. Wire. 2002, 25: 46-52.
    [27] Zhang Xian Hong, Ruan XueYu, Osakada K. Forge ability of AZ31B magnesium alloy in warm forging [J]. Transactions of Nonferrous Metals Society of China (English Edition). 2003, 13: 632-635.
    [28]吕炎,徐福昌,薛克敏,许沂.镁合金上机匣等温精锻工艺的研究[J].哈尔滨工业大学学报, 2000, 32(4):127-129.
    [29]李国俊,张治民,李旭斌.镁合金散热器成形工艺的研究[J].轻合金加工技术. 2005, 33 (2):41-43.
    [30] Liu Y, Wu X, Li Z C, et al. Superplasticity and microstructural evolution of a large-grained Mg alloy [A]. Proceedings of International Symposium on Materials Science and Technology [C]. Harbin China. 2000, 1:127-130.
    [31] Chen F X, Su J H, Yang Y L, et al. Research on superplasticity and superplastic extrusion of MB26 Magnesium alloy [J]. Mater. Sci. Technol. 2001, 17(1):147-148.
    [32]吴立鸿,关绍康,王利国等.锻造镁合金及影响锻造成形的几个关键因素[J].锻压技术,2006,(4):7-10.
    [33]刘楚明,刘子娟,朱秀荣等.镁及镁合金动态再结晶研究进展[J].中国有色金属学报,2006,(1):1-12.
    [34]曹韩学,龙思远.多场交互作用下镁合金塑性变形研究[J].中国机械工程,2007,(18):361-364.
    [35]苏丹,周飞,彭颖红等.有限体积法仿真金属锻造过程及其关键技术[J].系统仿真学报, 2003, 15(4):534-537.
    [36]余琨,黎文献,王日初等. Mg-5.6Zn-0.7Zr-0.8Nd合金高温塑性变形的热/力模拟研究[J].金属学报,2003,39(5):492-498.
    [37] J. Bohlen, S.B.Yi, J. Swiostek, D. Letzig, H.G. Brokmeier, K.U. Kainer. Microstructure and texture development during hydrostatic extrusion of magnesium alloy AZ31 [J]. Scripta Materialia. 2005, 53:259-264.
    [38]陈振华,夏伟军,程永奇,傅定发.镁合金织构与各向异性[J].中国有色金属学报. 2005, 15(1):1-10.
    [39]刘助柏,张庆,王连东等.锻造理论与工艺的进展[J].燕山大学学报, 2000,24(4):298-301.
    [40]王连东,李仕华,刘助柏.墩粗工艺理论与技术的研究进展[J].中国机械工程, 2001,12(4): 474-477.
    [41]中国机械工程学会锻压学会.锻压手册[M].北京:机械工业出版社,1996:269-271.
    [42]汪大年等.金属塑性成形原理[M].机械工业出版社. 1985.
    [43]詹艳然,吴乐尧,王仲仁.金属体积成形过程中温度场的分析[J].塑性工程学报, 2001,8(4):13-16.
    [44]张津,章宗和.镁合金及应用[M].北京:化学工业出版社,2004:5-7.
    [45]曹韩学,龙思远,廖慧敏等.温度对镁合金铸锭压缩变形行为的影响[J].重庆大学学报,2005,(28):9-11.
    [46]张少明,杨必成,樊中运等.镁合金AZ61的流变挤压工艺和组织特征[J].中国有色金属学报,2007,(17):1423-1428.
    [47]汪凌云,黄光胜,范永革等.变形AZ31镁合金的晶粒细化[J].中国有色金属学报,2003,(13):594-597.
    [48]崔忠圻.金属学与热处理[M].北京:机械工业出版社,2000.
    [49]曲家惠,李四军,王福.AZ31镁合金挤出棒锻造变形时的组织与织构的变化[J].材料与冶金学报,2006,(5):221-230.
    [50] Watanabe H,Tsutsui H,Mukai T,etc.Deformation mechanism in a coarse-grained Mg-Al-Zn alloy at elevated temperatures[J].International Journal of Plasticity,2001,(17):387-397.
    [51] Ion S E, Hunphreys F J, White S H. Dynamic Recrystallization and the development of Macrostructure during the High Temperature Deformation of Magnesium[J]. Acta Mater, 1982, Vol.30, 1909.
    [52] K.H马图哈.材料科学与技术丛书(第8卷)非铁合金的结构与性能[M].科学出版社. 1999.
    [53] T. Laser, M.R. Nürnberg, A. Janz, Ch. Hartig, D. Letzig, R. Schmid-Fetzer, R. Bormann. The influence of manganese on the microstructure and mechanical properties of AZ31 gravity diecast alloys [J]. Acta Materialia. 2006, 54:3033-3041.
    [54] Teng-Shih Shih, Jing-Hwe Wang, Kow-Zong Chong. Combustion of magnesium alloys in air[J]. Materials Chemistry and Physics. 2004, 85:302–309.
    [55] Jing Zhang, Rulin Zuo, Youxing Chen, Fusheng Pan, Xiaodong Luo. Microstructure evolution during homogenization of aτ-type Mg-Zn-Al alloy[J]. Journal of Alloys and Compounds.2006.
    [56]刘正,张奎,曾小勤.镁基轻质合金理论基础及其应用[M].机械工业出版社,2002,9:62.
    [57] R.M. Wang, A. Eliezer, E. Gutman. An investigation on the microstructure of an AM50 magnesium alloy [J], Materials Science and Engineering. 2003, A355:201-207.
    [58]郑修麟.工程材料的力学行为[M].北京工业大学出版社,2004.
    [59]陈振华.变形镁合金[M].化学工业出版社. 2004.
    [60] S.B. Yi, S. Zaefferer, H.-G. Brokmeier. Mechanical behaviour and microstructural evolution of magnesium alloy AZ31 in tension at different temperatures[J]. Materials Science and Engineering. 2006, A 424:275-281.
    [61] Nie J F. Effects of precipitati shape and orientation on dispersion strengthening in magnesium alloys [J]. Scripta Materialia. 2003, 48:1009.
    [62]龙思远,曹凤红.镁合金复合成形方法[P].中国, ZL200810069225.7, 2008.7.9.
    [63]赵俊.半连续铸锭的工艺故障及预防措施[J].山西机械,2001年增刊:136-138
    [64] Shaoyong Xu, Siyuan Long, Fenge Li. A novel squeeze casting process for producing magnesium wheels [J]. Material Science Forum. 2007, 546-549:113-118.

© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号

地址:北京市海淀区学院路29号 邮编:100083

电话:办公室:(+86 10)66554848;文献借阅、咨询服务、科技查新:66554700