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高速冲击细化晶粒方法研究
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摘要
磁脉冲成形的变形速率为准静态成形的100-1000倍。能显著提高金属的成形能力,同时,可使材料从微观组织到力学性能产生一系列的改变。因此本文从数值模拟、工艺实验、微观组织分析三个方面,对纯Cu棒、Q235板在脉冲磁场力驱动下的冲击变形和晶粒细化等内容进行了研究。
     利用DEFORM-3D得到了圆棒磁脉冲高速镦粗和平板磁脉冲高速冲击的载荷-行程曲线,并分析了平板磁脉冲高速冲击后板材的等效应变分布规律。结果表明,每次变形过程中,板材弯曲延伸区和未变形区会产生协调变形,等效应变在板长方向分布不均匀,导致板材的左右两端会产生约1个齿宽的“畸变区”,在板中间有小幅波动,波动幅度随着压制道次的增加而变大。
     冲击变形试样的显微组织观察表明,圆棒磁脉冲高速镦粗和平板磁脉冲高速冲击方法都有效细化了材料的晶粒。在圆棒磁脉冲高速镦粗条件下,纯Cu棒由原始的200μm细化为大量微米级细晶和拥有微米级亚结构的粗晶;在平板磁脉冲高速冲击条件下,Q235板平均晶粒尺寸由20.7μm细化为5.15μm。硬度分析结果表明,在本文研究条件下,纯Cu试样的加工硬化现象不显著,但心部硬度高于其他部位。Q235板A区和B区的硬度都随着道次的增加而上升,在第1道次时上升幅度最大,经过4道次变形后,A区与B区硬度差异消失; A区和B区的I.F.值先增大后减小,表明加工硬化不均匀性在第1道次时上升最大,而后逐渐减小。
     进行了平板磁脉冲高速冲击与CGP的比较研究,结果表明,平板磁脉冲高速冲击能够延缓裂纹的产生,变形更均匀,增加板材的可压制道次;平板磁脉冲高速冲击细化晶粒能力更强,相同道次下,细化速率更快,板材晶粒弯曲的现象不明显;平板磁脉冲高速冲击下的硬度要低;平板磁脉冲高速冲击下条件下板材A区和B区的I.F.值要比CGP的要小,因此平板磁脉冲高速冲击改善了材料的加工硬化均匀性。
The deformation rate of magnetic pulse forming is 100-1000 times as that of the Quasi-static forming, and magnetic pulse forming can expand the forming limit of metallic materials effectively and lead to a series of improvements in materials’mechanical properties and microstructure. In this paper, the punching deformation and the refining process of pure Cu and Q235 steel under the magnetic pulse forming process are studied from the aspects of simulation, test and microstructure analysis.
     The load-stroke Curves of high-speed upsetting of magnetic pulse and high-speed impact of magnetic pulse are obtained by DEFORM-3D. The effective strain of Q235 plate’s high-speed impact of magnetic pulse is analyzed and 3 different strain parts are found. Firstly both the Curved and extended areas and the unreformed parts have a compatible deformation during the deformation process; secondly, the distribution of effective strain in the plate is relatively well-proportioned in the direction of thickness and width orientation while it is seriously uneven in the length direction, whereas, there is a distorted area with the width of one tooth in the right and left end of the plate respectively. Thirdly, the fluctuation of effective strain in the length direction becomes greater with the increase of pressing numbers.
     Based on metallographic observation, the laws of grain refinement of high-speed upsetting of magnetic pulse and high-speed impact of magnetic pulse are obtained in this paper. Under Electromagnetic high-speed upsetting, the pure Cu is ultimately subdivided into a large number of submicron grains and coarse-grains with sub-micron structures. Under high-speed impact of magnetic pulse, Q235 steel refines the average grain size from 20.7μm to 5.15μm. Based on the observation, the hardness of Cu bar in vertical section and in horizontal section will increase as the pressure increases, but the change is small. The phenomenon indicates the hardness improved little and the central section is harder than other areas. Under high-speed impact of magnetic pulse, the average hardness of section A and section B will increase with the upsetting times increasing. The maximum augment happened in the 1st term. Although the initial hardness of the section A and section B are different, after four terms, both sections could achieve the same hardness at last. However, the non-uniformity of hardness in section B is more serious than that in section A.
     Based on the comparison of the High-speed impact of magnetic pulse and the constrained groove pressing, the following results is obtained: 1) high-speed impact of magnetic pulse can delay the cracks as the number of upsetting times increases. And under the same condition, the high-speed impact of magnetic pulse’s deformation is more uniform.2) the high-speed impact of magnetic pulse elucidates the stronger refinement ability and higher refining rate. Meanwhile grains’bending phenomenon is not obvious. The angle of the direction of the grain and the board will be smaller .3) In the 1st deformation term, the hardness of the sheet under two methods will rapidly increase, but under high-speed impact of magnetic pulse are greater and surprisingly get a lower final hardness value.4) under high-speed impact of magnetic pulse the I.F. values of section A and section B are smaller than those under constrained groove pressing, so the high-speed impact method can improve material's hardness uniformity.
引文
[1] U. Erb, A. M. El-Sherik, G. Palumbo, et al. Synthesis, structure and properties of electroplated nanocrystalline materials[J]. Nanostructured Materials, 1993, 2: 383-390
    [2] C. C. Koch, Y. S. Cho. Nanocrystals by high energy ball milling[J]. Nanostructured Materials, 1992, 1: 207-212
    [3] Z. Horita, T. Fujinami, T. G. Langdon. The potential for scaling ECAP: effect of sample size on grain refinement and mechanical properties[J]. Materials Science Engineering A, 2001, 318: 34-41
    [4] Y. W. Tham, M. W. Fu, H.H. Hng, M. S. Yong, K. B. Lim, J. Deformation Study of Multi-pass ECAE Process Producing Bulk Nanostructured Materials[J]. Materials and Manufacturing processes, 2006, 21: 501-506
    [5] R. Z. Valiev, R. K. Islamgaliev, I. V. Alexandrov. Bulk nanostructured materials from severe plastic deformation[J].Progress in Materials Science, 2000, 45(2): 103-189
    [6] Z. Horita, T.G. Langdon. Achieving exceptional superplasticity in a bulk aluminum alloy processed by high-pressure torsion[J]. Scripta Materialia, 2008, 58: 1029-1032
    [7] R. Z. Valiev, T. G. Langdon. Principles of equal-channel angular pressing as a processing tool for grain refinement Prog[J]. Mater. Sci, 2006, 51:881-981
    [8] L. Olijnik, A. Rosochowski. Methods of fabricating metals for nano-technology[J]. Bull. Pol. Ac. Tech, 2005, 53(4): 413-423
    [9] J. Huang, Y.T. Zhu, D. J. Alexander, X. Liao, T.C. Lowe, R.J. Asaro. Development of Repetitive Corrugation and Straightening[J]. Materials Science and Engineering A, 2004, 371:35-39
    [10] D. H. Shin, J. J. Park, Y. S. Kim, et al. Constrained groove pressing and its application to grain refinement of aluminum[J]. Materials Science and Engineering A, 2002, 328: 98-103
    [11] N. Tsuji, Y. Saito, H. Utsunomiya, S. Tanigawa. Ultra-fine grained bulk steel produced by accumulative roll-bonding (ARB)process[J]. Scripta Materialia, 1999, 40: 795-800
    [12]康志新,彭勇辉.剧塑性变形制备超细晶/纳米晶结构金属材料的研究现状和应用展望[J].中国有色金属学报, 2010, 20(4): 587-598
    [13] E. V. Psyk, D. Risch, et al. A review-electromagnetic forming[J]. Journal of Materials Processing Technology, 2011, 211(5): 787-829
    [14]赵志衡,李春峰.电磁成形用螺线管线圈电感的研究[J].哈尔滨工业大学学报, 2000, 32(5): 64-66
    [15] V. J. Vohnout. A Hybrid Quasi-static/Dynamic Process for Forming Large Sheet Metal Parts from Aluminum Alloys. Ph. D. Dissertation of Ohio State University, 1998: 1-199
    [16] V. S. Balanethiram, G. S. Daehn. Enhanced Formability of Interstitial Free Iron at High Strain Rate[J]. Scripta Metallurgica et Materialia, 1992, 27: 1783-1788
    [17] V. S. Balanethiram, G. S. Daehn. Hyperplasticity: Increased Forming Limits at High Workpiece Velocity[J]. Scripta Metallurgica et Materialia, 1994, 30(4): 515-520
    [18] V. S. Balanethiram, X. Y. Hu, G. S. Daehn. Hyperplasticity: Enhanced Formability at High Rates[J]. Journal of Materials Processing Technology, 1994, 45: 595-600
    [19] F. W. Bach, L. Walden. Microstructure and Mechanical Properties of Copper Sheet after Electromagnetic Forming[J]. ZWF Zeitschrift fur Wirtschaftlichen Fabrikbetrieb, 2005, 100(7-8): 430-434
    [20] X. Y. Hu, R. H. Wagoner, G. S. Daehn, S. Ghosh. The Effect of Inertia on Tensile Ductility[J]. Metallurgical Transactions, 1994, 25A: 2723-2735
    [21] X. Y. Hu, G. S. Daehn. Effect of Velocity on Flow Localization in Tension[J]. Acta Materialia, 1996, 44(3): 1021-1993
    [22] M. M. Altynova, X. Y. Hu, G. S. Daehn. Increased Ductility in High Velocity Electromagnetic Ring Expansion[J]. Metallurgical and Materials Transactions. 1996, 27A: 1837-1844
    [23] E. Rafizadeh, A. Mani, M. Kazeminezhad. On the evolution of flow stress during constrained groove pressing of pure copper sheet[J]. Comput Material Science, 2009, 45: 855-859.
    [24] A. Shirdel, A. Khajeh, M. M. Moshksar. Experimental and finite element investigation of semi-constrained groove pressing process[J]. Materials andDesign, 2010, 31: 946-950
    [25] J. W. Lee, J. J. Park. Numerical and experimental investigations of constrained groove pressing and rolling for grain refinement[J]. Journal of Materials Processing Technology, 2002, 130-131: 208-231
    [26] A. Krishnaiah, U. Chakkingal, V. Penugopal. Production of ultrafine grain sizes in aluminium sheets by severe plastic deformation using the technique of groove pressing[J]. Scripta Materialia, 2005, 52: 1229-1233
    [27] A. Krishnaiah, U. Chakkingal, P. Venugopal, et al. Applicability of the groove pressing technique for grain refinement in commercial purity copper[J]. Materials Science and Engineering A, 2005, 410: 337-340
    [28] Peng Kaiping, et al. Microstructure dependence of a Cu–38Zn alloy on processing conditions of constrained groove pressing[J]. Acta Materialia, 2009, 57: 5543-5553
    [29] G. Ganesh Niranjan, Uday Chakkingal. Deep drawability of commercial purity aluminum sheets processed by groove Pressing[J]. Journal of Materials Processing Technology, 2010, 210: 1511-1516
    [30] B. Avitzur. Metal Forming: Processes and Analysis[M]. New York: Mc Graw-Hill, 1968: 107-109
    [31] Peng Kaiping, Su Lifeng, L. Leon, et al. Grain refinement and crack prevention in constrained groove pressing of two-phase Cu-Zn alloys [J]. Scripta Materialia, 2007, 56: 987-990
    [32] F. Khodabakhshi, M. Kazeminezhad, A. H. Kokabi. Constrained groove pressing of low carbon steel: Nano-structure and mechanical properties[J]. Materials Science and Engineering A, 2010, 527: 4043-4049
    [33] A. Thirugnanam, T. S. Sampath Kumar, Uday Chakkingal. Tailoring the bioactivity of commercially pure titanium by grain refinement using groove pressing[J]. Materials Science and Engineering C, 2010, 30: 203-208
    [34]卢洪,彭开萍.影响反复模压变形法细化两相合金的因素[J].金属热处理, 2008, 33: 46-49
    [35]吴永泉,杨开怀,陈文哲.限制模压变形后5052铝合金的组织与显微硬度[J].材料热处理技术, 2009, 38: 8-14
    [36] Y. Fukuda, K. Oh-ishi, Z. Horita, T. G. Langdon. Processing of a low-carbon steel by equal-channel angular pressing[J]. Acta Materialia, 2002, 50(6):1359-1368
    [37] D. H. Shin, B. C. Kim, Y. S. Kim, K. T. Park. Microstructural evolution in a commercial low carbon steel by equal channel angular pressing [J]. Acta Materialia, 2000, 48(9): 2247-2255
    [38] D.H. Shin, I. Kim, J. Kim, K. T. Park. Grain refinement mechanism during equal-channel angular pressing of a low-carbon steel[J]. Acta Materialia. 2001, 49: 1285-1292
    [39] D.H. Shin, J. J. Pak, Y. K. Kim, K. T. Park, Y. S. Kim. Effect of pressing temperature on microstructure and tensile behavior of low carbon steels processed by equal channel angular pressing [J]. Materials Science and Engineering A, 2002, 323: 409-415
    [40] D.H. Shin, K. T. Park. Ultrafine grained steels processed by equal channel angular pressing[J]. Materials Science and Engineering A, 2005, 410/411: 299-302
    [41] A. L. M. Costa, A. C. C. Reis, L. Kestens, M. S. Andrade. Ultra grain refinement and hardening of IF-steel during accumulative roll-bonding[J]. Materials Science and Engineering A, 2005, 406: 279-285
    [42] N. Kamikawa, T. Sakai, N. Tsuji. Effect of redundant shear strain on microstructure and texture evolution during accumulative roll-bonding in ultralow carbon IF steel[J]. Acta Materialia, 2007, 55: 5873-5888
    [43] N. Kamikawa, N. Tsuji, Y. Minamino. Effect of rolling reduction on ultrafine grained structure and mechanical properties of low-carbon steel thermomechanically processed from martensite starting structure[J]. Sci. Technol. Adv. Mater, 2003, 5: 163-172
    [44] ]N. Tsuji, R. Ueji, Y. Minamino. A new and simple process to obtain nano-structured bulk low-carbon steel with superior mechanical property[J]. Scripta Materialia, 2002, 47: 69-76
    [45] E. Rafizadeh, A. Mani, M. Kazeminezhad. The effects of intermediate and post-annealing phenomena on the mechanical properties and microstructure of constrained groove pressed copper sheet[J]. Materials Science and Engineering A, 2009, 515: 162-168
    [46]付尔聪.连续等通道挤压方法细化铜材晶粒的研究[D].大连:大连交通大学, 2005: 45-46
    [47]董月成.超细晶纯铜的动态力学性能研究[M].南京理工大学,硕士论文
    [48] A. Rusinek.Constitutive relations in 3-D for a wide range of strain rates and temperatures–Application to mild steels[J]. International Journal of Solids and Structures, 2007, 44: 5611-5634

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