变诱导法铝合金（6061）半固态坯料制备及触变成型研究
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摘要
铝及其合金是有色金属中用途较广的轻金属之一,具有高的比强度、比刚度、塑性好、导电与导热性好、且具有较好耐蚀性,是制造航天和航空装备的理想材料。对锻造无法加工成形的复杂制件,若采用机加工的方法则浪费材料,且加工周期长,成本高;若用铸造的方法,则制件性能得不到保证。半固态金属加工是一种新发展的一次近净成形复杂形状制件技术,其制件力学性能接近锻件,为复杂制件成形开辟一条新路。本文以6061铝合金为研究对象,通过应变诱导法(SIMA法)制造半固态坯料,研究其半固态压缩状态下的力学特性,然后以保险阀壳体件为试验对象,对其各种方式的触变成形过程进行数值模拟,为该零件的触变成形研究提供参考和依据。
在前期工作中,应用镦粗法制备6061铝合金半固态坯料,并通过半固态压缩实验建立该材料真应力-真应变模型;第二阶段应用三维造型软件对成形薄壁壳体件所需的模具进行了参数化实体造型,然后在Deform3D平台上对该零件的各种成形方法和过程进行了数值模拟,研究了模具结构和成形方法对成型结果的影响;第三阶段通过半固态模锻实验验证数值模拟的结果,对保险阀壳体件的半固态成形工艺进行初步的探索和研究。
通过显微组织观察证明利用镦粗法可以一定程度细化晶粒;通过半固态等温压缩实验研究了6061铝合金在半固态下的压缩力学行为,证明挤压后冷变形态6061铝合金可以在较小的力下实现较大的变形,且均具有温度和应变速率的敏感性;通过不同成形方法的数值模拟实验,证明目前的模具结构下采用两侧推挤触变模锻法成形带侧凹的保险阀壳体件会造成夹料的现象,从而无法完全充型;如果用顶部正挤压法则可以实现液态模锻成形,但是无法实现半固态触变成形;如果改变分型面的位置,采用正挤压法则可以成形不带侧凹的保险阀壳体零件;如果将零件的颈部去掉,使用改变分型面后的正挤压法可以成形。通过实际的成形实验验证了数值模拟的结果,并与数值模拟的结果很吻合。
本试验提出最终解决问题的方法,改变模具结构,使用正挤压法成型出去掉颈部的壳体件,再使用机加工的方式去掉颈部多余的材料。
Aluminium alloy is a kind of light colored metal which is widely used, it has high specific strength and high specific rigidity; it also has good electric conductivity and good conductivity for heat and its strain resistance is good too, so it is a ideal material for aviation equipment. In general, machining is used to fabricate complicated parts that can not be made by forging process. A quantity of raw material is thus wasted in a very long process cycle, resulting in high manufacturing cost. Semi-solid metal working, a newly developed process for near-net shaping complicated parts, with mechanical properties approach to those of forging parts, will establish a new method for making such complicated parts. Taking 6061 aluminium alloy as object, made it’s billet by SIMA ( Strain Induced-Melt Activation ) method. The mechanical character and the simulation of it’s shapping process are then studied which could be a reference of the thixo-mold experiment.
In the first period, the semi-solid billet was preparated by SIMA method, and then it’s equivalent stress and equivalent strain model was set up by compression tests. During the second period, mould of the shell shapped part in three dimension was set up using Pro-Engineer(Proe)software, and then the shapping process of the part was simulated by using the Deform3D software, so the effect of the mould fabric and the forging method to shapping the part was then gained. During the last period, the forging experiments were done which proved the results of the simulation, and the primary research on the forging process of the valve was finished.
By observing the microstructure of the billet which was cold upsetted we found that cold upsetting method could fine the grain size on some degree. Through a large number of compression tests in 6061 aluminium’s semi-solid state, mechanical behaviors during semi-solid deformation process for the 6061 aluminium alloy were investigated, and found that a larger deformation was realized under less force for cold upsetting state billet and this kind of billet is sensitive to temperature and strain rate. Through a lot of simulation tests, the extruding from the two side method can’t forming the valve for the material extruded from the top method, the valve can be formed in liquid state but can’t be formed in semi-solid state. If change the parting plan, then the valve without side hollows can be formed by direct extrusion method, if get rid of the cervix, then it can be formed by direct extrusion method with the parting plane in the biggest diameter position.
The last solution is: form the valve without cervix by direct extrusion method and then machine the unwanted material.
在前期工作中,应用镦粗法制备6061铝合金半固态坯料,并通过半固态压缩实验建立该材料真应力-真应变模型;第二阶段应用三维造型软件对成形薄壁壳体件所需的模具进行了参数化实体造型,然后在Deform3D平台上对该零件的各种成形方法和过程进行了数值模拟,研究了模具结构和成形方法对成型结果的影响;第三阶段通过半固态模锻实验验证数值模拟的结果,对保险阀壳体件的半固态成形工艺进行初步的探索和研究。
通过显微组织观察证明利用镦粗法可以一定程度细化晶粒;通过半固态等温压缩实验研究了6061铝合金在半固态下的压缩力学行为,证明挤压后冷变形态6061铝合金可以在较小的力下实现较大的变形,且均具有温度和应变速率的敏感性;通过不同成形方法的数值模拟实验,证明目前的模具结构下采用两侧推挤触变模锻法成形带侧凹的保险阀壳体件会造成夹料的现象,从而无法完全充型;如果用顶部正挤压法则可以实现液态模锻成形,但是无法实现半固态触变成形;如果改变分型面的位置,采用正挤压法则可以成形不带侧凹的保险阀壳体零件;如果将零件的颈部去掉,使用改变分型面后的正挤压法可以成形。通过实际的成形实验验证了数值模拟的结果,并与数值模拟的结果很吻合。
本试验提出最终解决问题的方法,改变模具结构,使用正挤压法成型出去掉颈部的壳体件,再使用机加工的方式去掉颈部多余的材料。
Aluminium alloy is a kind of light colored metal which is widely used, it has high specific strength and high specific rigidity; it also has good electric conductivity and good conductivity for heat and its strain resistance is good too, so it is a ideal material for aviation equipment. In general, machining is used to fabricate complicated parts that can not be made by forging process. A quantity of raw material is thus wasted in a very long process cycle, resulting in high manufacturing cost. Semi-solid metal working, a newly developed process for near-net shaping complicated parts, with mechanical properties approach to those of forging parts, will establish a new method for making such complicated parts. Taking 6061 aluminium alloy as object, made it’s billet by SIMA ( Strain Induced-Melt Activation ) method. The mechanical character and the simulation of it’s shapping process are then studied which could be a reference of the thixo-mold experiment.
In the first period, the semi-solid billet was preparated by SIMA method, and then it’s equivalent stress and equivalent strain model was set up by compression tests. During the second period, mould of the shell shapped part in three dimension was set up using Pro-Engineer(Proe)software, and then the shapping process of the part was simulated by using the Deform3D software, so the effect of the mould fabric and the forging method to shapping the part was then gained. During the last period, the forging experiments were done which proved the results of the simulation, and the primary research on the forging process of the valve was finished.
By observing the microstructure of the billet which was cold upsetted we found that cold upsetting method could fine the grain size on some degree. Through a large number of compression tests in 6061 aluminium’s semi-solid state, mechanical behaviors during semi-solid deformation process for the 6061 aluminium alloy were investigated, and found that a larger deformation was realized under less force for cold upsetting state billet and this kind of billet is sensitive to temperature and strain rate. Through a lot of simulation tests, the extruding from the two side method can’t forming the valve for the material extruded from the top method, the valve can be formed in liquid state but can’t be formed in semi-solid state. If change the parting plan, then the valve without side hollows can be formed by direct extrusion method, if get rid of the cervix, then it can be formed by direct extrusion method with the parting plane in the biggest diameter position.
The last solution is: form the valve without cervix by direct extrusion method and then machine the unwanted material.
引文
1.刘静安,谢水生.铝合金材料的应用与技术开发.冶金工业出版社, 2004: 62~86
2.谢水生,黄生宏.半固态金属加工技术及其应用.冶金工业出版社, 1999: 1~45
3.吴秀铭.二十一世纪最有发展前景的现代加工新技术.有色金属工业.2000, (7): 1~4
4. Bahdapeb B.N等.变形铝合金的细化处理.王永海等译.冶金工业出版社, 1988: 56~72
5. Guo Jun, Xie Shuisheng, Huang Shenghong. Advanced Materials and Processes. on the Fourth Sino-Russion symposium. 1997:242
6. Kopp R, Neudenberger D,Winning G,Optimisation of the forming variants forging and transverse impact extrusion with alloys in semi-solid state. Chiarmetta G.L.-Rosso M,Turin. Proc.of 6 Int. Conference,Semi-Solid Processing of Allpys and Composites, Italy,2000:295~300
7.康永林,毛卫民等.金属材料半固态加工理论与技术.科学出版社, 2004: 6~10
8.杨晓婵,半固态金属成形技术在国外的研究与应用.矿冶. 2000, (9) : 1-3
9.钟晓萍,伍学高.激光增强电镀镍的研究.表面技术. 1994, (7): 108~110.
10.祖丽君. SiCp/2024复合材料半固态触变成形研究.哈尔滨工业大学博士学位论文.2001:4~60
11. M. Kiuchi, J. Yanagimoto, H. Yokobayashi. A New Mathematical Model to Simulate Flow of Mushy/Semi-Solid Alloys. Proc. of the 6th Int. Conference on the Semi-Solid Processing of Alloys and Composites. Torino, Italy, 2000: 507~514
12. T.H.Imwinkelried, T.H. Schnorf, J.R. Gabathuler, et al. Mould Optimisation of the Thixoforming Process by Numerical Modelling. Proc. of the 6th Int. Conference on the Semi-Solid Processing of Alloys and Composites. Torino, Italy, 2000: 515~520
13. M.L. Tims, J. Xu, F.R. Dax. Computer Based Numerical Analysis of Semi-Solid Metal Working. Proc. of the 4th Int. Conference on the Semi-SolidProcessing of Alloys and Composites. Sheffield, England, 1996: 120~125
14. C.G. Kang, J.H. Yoon. A Finite Element Analysis on the Upsetting Process of Semi-Solid Aluminum Material. J. Mater. Process. Tech. 1997, 66(1-3): 76~84
15.高志强,王云华,苏华钦.半固态合金触变铸造数值模拟方法的研究.特种铸造及有色合金.1997, (6): 8~11
16.谢水生,李兴刚.半固态加工技术在镁合金零部件生产中的应用.2005, (2):39~48
17. K. Wagner ,A. Putz, U. Engel. Improvement of tool life in cold forging by locally optimized surfaces. Journal of Materials Processing Technology 2006 ,(177): 206~209
18. P. Petrov, V. Perfilov, S. Stebunov. Prevention of lap formation in near net shape isothermal forging technologyof part of irregular shape made of aluminium alloy A92618. Journal of Materials Processing Technology. 2006, (177): 218~223
19.马向平,陈威.自蔓延技术在模具上的应用研究.模具工业.2006:12-32
20.胡远猛,张励忠,李海开. B级钢轴箱体半固态挤压成型模具的研究.北京交通大学学报(自然科学版),2005 , 29 (4): 92~95.
21.林柏年,李德富.对半固态合金流变性能模型的讨论.特种铸造及有色合金.1994, 1: 35~37
22. Mclelland A R A,Henderson N G, Atkinson H V, etal. The evaluation of rheological measurements on Semi-Solid metal slurries[A].Stuart B and Merton C. Proceedings of 2 International Conference on Semi-Solid Processing of Alloys and Composites. Cambridge, Massachustts, 1992:290~295
23.丁志勇.半固态AlSi7Mg合金触变成形的成形特性及数学模型的研究.北京有色金属研究总院博士学位论文.2002: 1~88
24. Joly PA,Mehrabian R.The rheology of a partially solid alloy. Journey of Material Science,1976,(11):1393~1418
25. W.Nan,S.Guangji and Hanguo. Rheological Study of Partially Solidified Tin-Lead and Aluminium-Zina Alloy.J.Mater.Sci.1990, (31):715~722
26. L.S.Turng and K.KWang. Rheological and Modelling of Semi-Solid Sn-15%Pb Alloy.J.Mater.Sci.1991,(26) (8):2173~2183
27. P. Kumar, C.L.Martin and S.Brown. Constitutive Modeling and Characterization of the Flow behavior of Semi-Solid Metal Alloy Slurries-Ⅰ. The Flow Response Acta Metall. Mater. 1994, 42(11): 3595~3602
28. P. Kumar, C.L. Martin and S.Brown. Constitutive Modeling and Characterization of the Flow behavior of Semi-Solid Metal Alloy Slurries-Ⅱ. Structural Evolution under Shear Deformation. Acta Metall. Mater. 1994, 42(11): 3603~3614
29. H.Iwasaki,T.Mori,M.Maabuchi et al.Shear Deformation behavior of Al-5%Mg in Semi-Solid State. Acta. Mater. 1998,46(18):6351~6360
30.谢水生,李兴刚,江运喜.镁合金汽车轮毂半固态触变成形的刚-粘塑性有限元分析.塑性工程学报.2005, 12(2): 89~93
31. Kapranos P,Liu T Y,Atkinson H V.Inverstigation into the rapid compression of semi-solid alloys slugs.J.Mater. Processing Technol.2001,111:31~36
32.崔建忠,夏克农.2618铝合金半固态压缩变形特性.中国有色金属学报.1999, 9(Suppl.1):35~37
33.洪慎章.半固态模锻的应用和发展.模具技术.1999, (1): 60~65
34. Abbas Ghaei a, Mohammad R. Movahhedy b. Die design for the radial forging process using 3D FEM. Journal of Materials Processing Technology. 2007 (182): 534~539
35. GUO Qiang, YAN Hong-ge, CHEN Zhen-hua, ZHANG Hui. Fracture behaviors of AZ80 magnesium alloy during multiple forging processes. Trans. Nonferrous Met. SOCC. hina 2006 (16): 922~926
36. Kinji Hirai,Hidetoshi Somekawa, Yorinobu Takigawa and Kenji Higashic. Superplastic forging with dynamic recrystallization of Mg–Al–Zn alloys cast by thixo-molding. Scripta Materialia 2007 (56) :237~240
37.田文彤.LC4合金半固态坯料SIMA生成及触变成形研究.哈尔滨工业大学.2002: 3
38. M.C. Flemings. Behavior of Metal Alloys in the Semisolid State. Metall.Trans.1991,(22A):957~981
39.弗莱明斯.凝固过程.冶金工业出版社.1981: 254
40.林钢.铝合金应用手册.机械工业出版社, 2006: 281~352
41.吴炳尧.半固态金属铸造工艺的研究现状及发展前景.铸造.1999,(3): 45~52
42.姜巨福.新SIMA法制备AZ91D半固态坯及其触变模锻研究.哈尔滨工业大学博士学位论文.2005: 58~64
43. Li Shubo,Wang Yanqiu, Zheng Mingyi, et al.Dynamic Crystallization of AZ91D Magnesium Alloy during Compression Deformation at Elevated Tempreture.Transactions of Nonferrous Metals Society of China. 2004, 14(2): 306~310
44. W.Nan, S.Guangji and Hanguo.Rheological Study of Partially Solidified Tin-Lead and Aluminium-Zina Alloy.J.Mater.Sci.1990,31:715~722
45. Zhihao Zhang, Jianxin Xie. A numerical simulation of super-plastic die forging process for Zr-based bulk metallic glass spur gear. Materials Science and Engineering . 2006 (433): 323~328
46.蒋鹏,贺小毛.半固态成形的工艺概况与模具材料选用[J].模具技术, 1998, (2): 54~60.
47. TOSHIO H,KAPRANOS P.Thixoforming processing in got castby a cooling slope and low super heat casting[A].Pro-ceedings of the 7-th International Conference Semi-solid Pro-cessing of Alloys and Composites. Tsukuba: Japan Societyfor Technology of Plasticity,2002: 12~31
48.路贵民,董杰,崔建忠.半固态浆料制备新技术-液相线铸造.特种铸造及有色合金(2001年中国压铸、挤压铸造、半固态加工学术年会论文集.2001: 221~223
49.姜巨福,罗守靖.等径道角挤压对AZ91D镁合金力学性能的影响.热加工工艺. 2004, (8): 3~6
50. E.J. Vinarcik, J.D. Taylor, K.Farris.Automotive Fuel System Component Design for ManufactureUsing the Semi-Solid Process. Proc. of the 5th Int.Conference on the Semi-solid Processing of Alloys and Composites. Dolden, Colorado, june23~25,1998:79~86
2.谢水生,黄生宏.半固态金属加工技术及其应用.冶金工业出版社, 1999: 1~45
3.吴秀铭.二十一世纪最有发展前景的现代加工新技术.有色金属工业.2000, (7): 1~4
4. Bahdapeb B.N等.变形铝合金的细化处理.王永海等译.冶金工业出版社, 1988: 56~72
5. Guo Jun, Xie Shuisheng, Huang Shenghong. Advanced Materials and Processes. on the Fourth Sino-Russion symposium. 1997:242
6. Kopp R, Neudenberger D,Winning G,Optimisation of the forming variants forging and transverse impact extrusion with alloys in semi-solid state. Chiarmetta G.L.-Rosso M,Turin. Proc.of 6 Int. Conference,Semi-Solid Processing of Allpys and Composites, Italy,2000:295~300
7.康永林,毛卫民等.金属材料半固态加工理论与技术.科学出版社, 2004: 6~10
8.杨晓婵,半固态金属成形技术在国外的研究与应用.矿冶. 2000, (9) : 1-3
9.钟晓萍,伍学高.激光增强电镀镍的研究.表面技术. 1994, (7): 108~110.
10.祖丽君. SiCp/2024复合材料半固态触变成形研究.哈尔滨工业大学博士学位论文.2001:4~60
11. M. Kiuchi, J. Yanagimoto, H. Yokobayashi. A New Mathematical Model to Simulate Flow of Mushy/Semi-Solid Alloys. Proc. of the 6th Int. Conference on the Semi-Solid Processing of Alloys and Composites. Torino, Italy, 2000: 507~514
12. T.H.Imwinkelried, T.H. Schnorf, J.R. Gabathuler, et al. Mould Optimisation of the Thixoforming Process by Numerical Modelling. Proc. of the 6th Int. Conference on the Semi-Solid Processing of Alloys and Composites. Torino, Italy, 2000: 515~520
13. M.L. Tims, J. Xu, F.R. Dax. Computer Based Numerical Analysis of Semi-Solid Metal Working. Proc. of the 4th Int. Conference on the Semi-SolidProcessing of Alloys and Composites. Sheffield, England, 1996: 120~125
14. C.G. Kang, J.H. Yoon. A Finite Element Analysis on the Upsetting Process of Semi-Solid Aluminum Material. J. Mater. Process. Tech. 1997, 66(1-3): 76~84
15.高志强,王云华,苏华钦.半固态合金触变铸造数值模拟方法的研究.特种铸造及有色合金.1997, (6): 8~11
16.谢水生,李兴刚.半固态加工技术在镁合金零部件生产中的应用.2005, (2):39~48
17. K. Wagner ,A. Putz, U. Engel. Improvement of tool life in cold forging by locally optimized surfaces. Journal of Materials Processing Technology 2006 ,(177): 206~209
18. P. Petrov, V. Perfilov, S. Stebunov. Prevention of lap formation in near net shape isothermal forging technologyof part of irregular shape made of aluminium alloy A92618. Journal of Materials Processing Technology. 2006, (177): 218~223
19.马向平,陈威.自蔓延技术在模具上的应用研究.模具工业.2006:12-32
20.胡远猛,张励忠,李海开. B级钢轴箱体半固态挤压成型模具的研究.北京交通大学学报(自然科学版),2005 , 29 (4): 92~95.
21.林柏年,李德富.对半固态合金流变性能模型的讨论.特种铸造及有色合金.1994, 1: 35~37
22. Mclelland A R A,Henderson N G, Atkinson H V, etal. The evaluation of rheological measurements on Semi-Solid metal slurries[A].Stuart B and Merton C. Proceedings of 2 International Conference on Semi-Solid Processing of Alloys and Composites. Cambridge, Massachustts, 1992:290~295
23.丁志勇.半固态AlSi7Mg合金触变成形的成形特性及数学模型的研究.北京有色金属研究总院博士学位论文.2002: 1~88
24. Joly PA,Mehrabian R.The rheology of a partially solid alloy. Journey of Material Science,1976,(11):1393~1418
25. W.Nan,S.Guangji and Hanguo. Rheological Study of Partially Solidified Tin-Lead and Aluminium-Zina Alloy.J.Mater.Sci.1990, (31):715~722
26. L.S.Turng and K.KWang. Rheological and Modelling of Semi-Solid Sn-15%Pb Alloy.J.Mater.Sci.1991,(26) (8):2173~2183
27. P. Kumar, C.L.Martin and S.Brown. Constitutive Modeling and Characterization of the Flow behavior of Semi-Solid Metal Alloy Slurries-Ⅰ. The Flow Response Acta Metall. Mater. 1994, 42(11): 3595~3602
28. P. Kumar, C.L. Martin and S.Brown. Constitutive Modeling and Characterization of the Flow behavior of Semi-Solid Metal Alloy Slurries-Ⅱ. Structural Evolution under Shear Deformation. Acta Metall. Mater. 1994, 42(11): 3603~3614
29. H.Iwasaki,T.Mori,M.Maabuchi et al.Shear Deformation behavior of Al-5%Mg in Semi-Solid State. Acta. Mater. 1998,46(18):6351~6360
30.谢水生,李兴刚,江运喜.镁合金汽车轮毂半固态触变成形的刚-粘塑性有限元分析.塑性工程学报.2005, 12(2): 89~93
31. Kapranos P,Liu T Y,Atkinson H V.Inverstigation into the rapid compression of semi-solid alloys slugs.J.Mater. Processing Technol.2001,111:31~36
32.崔建忠,夏克农.2618铝合金半固态压缩变形特性.中国有色金属学报.1999, 9(Suppl.1):35~37
33.洪慎章.半固态模锻的应用和发展.模具技术.1999, (1): 60~65
34. Abbas Ghaei a, Mohammad R. Movahhedy b. Die design for the radial forging process using 3D FEM. Journal of Materials Processing Technology. 2007 (182): 534~539
35. GUO Qiang, YAN Hong-ge, CHEN Zhen-hua, ZHANG Hui. Fracture behaviors of AZ80 magnesium alloy during multiple forging processes. Trans. Nonferrous Met. SOCC. hina 2006 (16): 922~926
36. Kinji Hirai,Hidetoshi Somekawa, Yorinobu Takigawa and Kenji Higashic. Superplastic forging with dynamic recrystallization of Mg–Al–Zn alloys cast by thixo-molding. Scripta Materialia 2007 (56) :237~240
37.田文彤.LC4合金半固态坯料SIMA生成及触变成形研究.哈尔滨工业大学.2002: 3
38. M.C. Flemings. Behavior of Metal Alloys in the Semisolid State. Metall.Trans.1991,(22A):957~981
39.弗莱明斯.凝固过程.冶金工业出版社.1981: 254
40.林钢.铝合金应用手册.机械工业出版社, 2006: 281~352
41.吴炳尧.半固态金属铸造工艺的研究现状及发展前景.铸造.1999,(3): 45~52
42.姜巨福.新SIMA法制备AZ91D半固态坯及其触变模锻研究.哈尔滨工业大学博士学位论文.2005: 58~64
43. Li Shubo,Wang Yanqiu, Zheng Mingyi, et al.Dynamic Crystallization of AZ91D Magnesium Alloy during Compression Deformation at Elevated Tempreture.Transactions of Nonferrous Metals Society of China. 2004, 14(2): 306~310
44. W.Nan, S.Guangji and Hanguo.Rheological Study of Partially Solidified Tin-Lead and Aluminium-Zina Alloy.J.Mater.Sci.1990,31:715~722
45. Zhihao Zhang, Jianxin Xie. A numerical simulation of super-plastic die forging process for Zr-based bulk metallic glass spur gear. Materials Science and Engineering . 2006 (433): 323~328
46.蒋鹏,贺小毛.半固态成形的工艺概况与模具材料选用[J].模具技术, 1998, (2): 54~60.
47. TOSHIO H,KAPRANOS P.Thixoforming processing in got castby a cooling slope and low super heat casting[A].Pro-ceedings of the 7-th International Conference Semi-solid Pro-cessing of Alloys and Composites. Tsukuba: Japan Societyfor Technology of Plasticity,2002: 12~31
48.路贵民,董杰,崔建忠.半固态浆料制备新技术-液相线铸造.特种铸造及有色合金(2001年中国压铸、挤压铸造、半固态加工学术年会论文集.2001: 221~223
49.姜巨福,罗守靖.等径道角挤压对AZ91D镁合金力学性能的影响.热加工工艺. 2004, (8): 3~6
50. E.J. Vinarcik, J.D. Taylor, K.Farris.Automotive Fuel System Component Design for ManufactureUsing the Semi-Solid Process. Proc. of the 5th Int.Conference on the Semi-solid Processing of Alloys and Composites. Dolden, Colorado, june23~25,1998:79~86