内部电磁搅拌对大规格2219铝合金铸锭组织及性能的影响
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摘要
针对普通半连铸大规格铝合金铸锭通常存在的晶粒粗大、组织不均匀以及由此导致的强度较低等问题,本研究在普通电磁搅拌和环缝式电磁搅拌的基础上,提出了一种新型熔体处理方法—内部电磁搅拌,并将此方法应用于2219铝合金半连铸试验。通过与普通半连铸对比,探究内部电磁搅拌对大规格铝合金铸锭组织及性能的影响,以期为半连铸更大规格的铝合金铸锭提供参考与借鉴。结果表明,相较于普通半连铸,内部电磁搅拌半连铸2219铝合金铸锭的晶粒更加细小,组织更加均匀,从边部到心部的晶粒直径均在127～151μm范围之内;第二相的尺寸减小,分布均匀且数量显著减少;铸锭的性能大幅提高,在延伸率和断面收缩率提高的情况下,平均抗拉强度提高了11%,达到389 MPa,平均屈服强度提高了10%,达到286 MPa,平均布氏硬度从HB 117.8提高到HB 137.8,增幅达17%,且铸锭的性能随着位置的变化波动较小;断口扫描发现铸锭中的疏松缺陷大幅减少。
Severe problems such as coarse grain, inhomogeneous microstructure and correspondingly lower strength usually exist in the large-sized aluminum alloy billet prepared by normal direct chill casting. According to those problems, a new melt treatment technique named internal electromagnetic stirring(I-EMS) was put forward, which was based on the normal electromagnetic stirring and annular electromagnetic stirring. The internal electromagnetic stirring was utilized for 2219 aluminum alloy direct chill casting experiment to explore its effects on microstructure and mechanical properties of billet by comparing with the normal direct chill casting, in order to provide references and suggestions for the larger-sized billet. The results showed that after melt treatment by internal electromagnetic stirring, the grains were finer and the microstructures were more uniform, of which the grain diameter were in the range of 127～151 μm. Moreover, the size and number of second phase decreased as well as it distributed homogeneously. Accordingly, its average tensile strength and yield strength increased by 11% and 10%, reaching to 389 and 286 MPa, respectively. The average Brignell hardness also increased by 17%, improving from HB 117.8 to HB 137.8. Furthermore, its properties fluctuated little with the position change while its porosities decreased significantly.
Severe problems such as coarse grain, inhomogeneous microstructure and correspondingly lower strength usually exist in the large-sized aluminum alloy billet prepared by normal direct chill casting. According to those problems, a new melt treatment technique named internal electromagnetic stirring(I-EMS) was put forward, which was based on the normal electromagnetic stirring and annular electromagnetic stirring. The internal electromagnetic stirring was utilized for 2219 aluminum alloy direct chill casting experiment to explore its effects on microstructure and mechanical properties of billet by comparing with the normal direct chill casting, in order to provide references and suggestions for the larger-sized billet. The results showed that after melt treatment by internal electromagnetic stirring, the grains were finer and the microstructures were more uniform, of which the grain diameter were in the range of 127～151 μm. Moreover, the size and number of second phase decreased as well as it distributed homogeneously. Accordingly, its average tensile strength and yield strength increased by 11% and 10%, reaching to 389 and 286 MPa, respectively. The average Brignell hardness also increased by 17%, improving from HB 117.8 to HB 137.8. Furthermore, its properties fluctuated little with the position change while its porosities decreased significantly.
引文
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[14] Zhang J K, Zhang Q, Li Y, Deng W Z, Yan C. Effects of electromagnetic stirring on solidification microstructure and central defects of gold-based alloy [J]. Rare Metal Materials and Engineering, 2017, 46(1): 274.(张俊凯, 张勤, 厉英, 邓文卓, 闫晨. 电磁搅拌对金基合金凝固组织和心部缺陷的影响 [J]. 稀有金属材料与工程, 2017, 46(1): 274.)
[15] Qi Y L, Jia G L, Zhang G Z. Effect of electromagnetic stirring on liquid metal fluid flow and solidification structure [J]. Foundry Technology, 2005, 26(2): 118.(齐雅丽, 贾光霖, 张国志. 电磁搅拌对液态金属运动及凝固组织的影响 [J]. 铸造技术, 2005, 26(2): 118.)
[16] Fan Z, Liu G. Solidification behaviour of AZ91D alloy under intensive forced convection in the RDC process [J]. Acta Materialia, 2005, 53(16): 4345.
[17] Li H T, Xia M, Jarry P, Scamans G M, Fan Z. Grain refinement in a AlZnMgCuTi alloy by intensive melt shearing: a multi-step nucleation mechanism [J]. Journal of Crystal Growth, 2011, 314(1): 285.
[18] Zhang G J, Yuan S P, Wang R H, Liu G, Sun J, Chen K H. Coupled influence of constituents and precipitates on ductile fracture of Al-Mg-Si alloys [J]. Chinese Journal of Nonferrous Metals, 2009, 19(11): 1894.)(张国君, 袁生平, 王瑞红, 刘刚, 孙军, 陈康华. 粗大第二相及时效析出相对Al-Mg-Si合金延性断裂的耦合影响 [J]. 中国有色金属学报, 2009, 19(11): 1894.)
[19] Wang X D, Li T J, Jin J Z. Research on feeding mechanism during metal solidification under rotating electromagnetic field[J]. Journal of Materials Engineering, 2001(11): 3.(王晓东, 李廷举, 金俊泽. 旋转电磁场作用下金属凝固补缩机理探讨 [J]. 材料工程, 2001, (11): 3.)
[20] Cao Z Q, Li T J, Zhang H L, Liu J D, Wang J C. Analysis on hot cracking depression reasons for 7050 aluminum alloy slab by soft-contact continuous casting [J]. Rare Metal Materials and Engineering, 2010, 39(12): 157.(曹志强, 李廷举, 张红亮, 刘吉东, 王家淳. 7050铝合金软接触连铸扁锭裂纹抑制原因分析 [J]. 稀有金属材料与工程, 2010, 39(12): 157.)
[21] Ammar H R, Samuel A M, Samuel F H. Porosity and the fatigue behavior of hypoeutectic and hypereutectic aluminum-silicon casting alloys [J]. International Journal of Fatigue, 2008, 30(6): 1024.
[22] Wang L, Fan X Y, Luo L S, Xu J G, Chen R R, Yi H Y, Zhou G Z, Wang N, Zhang J B, Su Y Q. Influence of traveling magnetic field on solidification defects and mechanical properties of ZL205A alloy sheet casts [J]. Rare Metal Materials and Engineering, 2016, 45(12): 3177.(王亮, 范学燚, 骆良顺, 许纪刚, 陈瑞润, 伊洪勇, 周国柱, 王宁, 张建兵, 苏彦庆. 行波磁场对ZL205A合金薄壁铸件凝固缺陷和力学性能的影响 [J]. 稀有金属材料与工程, 2016, 45(12): 3177.)
[2] Wang H M, Yi Y P, Huang S Q. Investigation of quench sensitivity of high strength 2219 aluminum alloy by TTP and TTT diagrams [J]. Journal of Alloys and Compounds, 2017, 690(5): 446.
[3] Zhang H, Tang L H, He K H, Li C B. Research on the casting technology of 2219 Al-alloy billets with large size and high performance [J]. Light Alloy Fabrication Technology, 2016, 44(12): 8.(张航, 唐露华, 何克淮, 李承波. 大规格高性能2219铝合金圆锭铸造工艺研究 [J]. 轻合金加工技术, 2016, 44(12): 8.)
[4] Eskin D G. Physical Metallurgy of Direct Chill Casting of Aluminum Alloys [M]. Boca Raton: CRC Press, 2008. 19.
[5] Yang D J, Xu K H, Ding P F, Zhang G Q, Chen K H. Analysis and improvement measures on casting property of 2219 aluminium alloy large diameter round ingot [J]. Aerospace Manufacturing Technology, 2014, (6): 1.(阳代军, 徐坤和, 丁鹏飞, 张国庆, 陈康华. 2219铝合金大直径圆锭铸造性能分析及其改进措施 [J]. 航天制造技术, 2014, (6): 1.)
[6] Xu K H, Zhang W X, Yang D J, Zhang G F, Li Y J, Liu D. Manufacture of aluminum alloy 2219 integral ring with 9m ultra-large diameter [J]. Forging and Stamping Technology, 2016, 41(10): 92.(徐坤和, 张文学, 阳代军, 张国方, 李姚君, 刘东. 9m级超大直径2219铝合金整体环件的研制 [J]. 锻压技术, 2016, 41(10): 92.)
[7] Chen T, Liu Z, Liu X M, Chen Z P. Solidified microstructure of semisolid A356-Ce alloy with two-way intermittent electromagnetic stirring [J]. Chinese Journal of Rare Metals, 2018, 42(1): 29.(陈涛, 刘政, 刘小梅, 陈志平. 双向间歇电磁搅拌对半固态A356-Ce合金凝固组织的影响施加复合电磁搅拌对A357合金微观组织的影响 [J]. 稀有金属, 2018, 42(1): 29.)
[8] Zhang Z F, Kim J M, Hong C P. Numerical simulation of grain structure evolution in solidification of an Al-5.0wt%Cu alloy under electromagnetic stirring and its experimental verification [J]. Isij International, 2005, 45(2): 183.
[9] Zhao J W, Guo A, Li H, Zhang X, Han J, Wu S S. Semisolid slurry of 7A04 aluminum alloy prepared by electromagnetic stirring and Sc, Zr additions [J]. China Foundry, 2017, 14(3): 188.
[10] Chen X R, Zhang Z F, Xu J. Effects of A-EMS processing parameters on semisolid slurry production [J]. Rare Metals, 2011, 30(2): 195.
[11] Tang M O, Xu J, Zhang Z F, Bai Y L. Effects of annulus gap on flow and temperature field in electromagnetic direct chill casting process [J]. Transactions of Nonferrous Metals Society of China, 2011, 21(5): 1123.
[12] Zhang Z F, Chen X R, Xu J, Shi L K. Numerical simulation on electromagnetic field, flow field and temperature field in semisolid slurry preparation by A-EMS [J]. Rare Metals, 2010, 29(6): 635.
[13] Bai Y L, Xu J, Zhang Z F, Shi L K. Annulus electromagnetic stirring for preparing semisolid A357 aluminum alloy slurry [J]. Transactions of Nonferrous Metals Society of China, 2009, 19(5): 1104.
[14] Zhang J K, Zhang Q, Li Y, Deng W Z, Yan C. Effects of electromagnetic stirring on solidification microstructure and central defects of gold-based alloy [J]. Rare Metal Materials and Engineering, 2017, 46(1): 274.(张俊凯, 张勤, 厉英, 邓文卓, 闫晨. 电磁搅拌对金基合金凝固组织和心部缺陷的影响 [J]. 稀有金属材料与工程, 2017, 46(1): 274.)
[15] Qi Y L, Jia G L, Zhang G Z. Effect of electromagnetic stirring on liquid metal fluid flow and solidification structure [J]. Foundry Technology, 2005, 26(2): 118.(齐雅丽, 贾光霖, 张国志. 电磁搅拌对液态金属运动及凝固组织的影响 [J]. 铸造技术, 2005, 26(2): 118.)
[16] Fan Z, Liu G. Solidification behaviour of AZ91D alloy under intensive forced convection in the RDC process [J]. Acta Materialia, 2005, 53(16): 4345.
[17] Li H T, Xia M, Jarry P, Scamans G M, Fan Z. Grain refinement in a AlZnMgCuTi alloy by intensive melt shearing: a multi-step nucleation mechanism [J]. Journal of Crystal Growth, 2011, 314(1): 285.
[18] Zhang G J, Yuan S P, Wang R H, Liu G, Sun J, Chen K H. Coupled influence of constituents and precipitates on ductile fracture of Al-Mg-Si alloys [J]. Chinese Journal of Nonferrous Metals, 2009, 19(11): 1894.)(张国君, 袁生平, 王瑞红, 刘刚, 孙军, 陈康华. 粗大第二相及时效析出相对Al-Mg-Si合金延性断裂的耦合影响 [J]. 中国有色金属学报, 2009, 19(11): 1894.)
[19] Wang X D, Li T J, Jin J Z. Research on feeding mechanism during metal solidification under rotating electromagnetic field[J]. Journal of Materials Engineering, 2001(11): 3.(王晓东, 李廷举, 金俊泽. 旋转电磁场作用下金属凝固补缩机理探讨 [J]. 材料工程, 2001, (11): 3.)
[20] Cao Z Q, Li T J, Zhang H L, Liu J D, Wang J C. Analysis on hot cracking depression reasons for 7050 aluminum alloy slab by soft-contact continuous casting [J]. Rare Metal Materials and Engineering, 2010, 39(12): 157.(曹志强, 李廷举, 张红亮, 刘吉东, 王家淳. 7050铝合金软接触连铸扁锭裂纹抑制原因分析 [J]. 稀有金属材料与工程, 2010, 39(12): 157.)
[21] Ammar H R, Samuel A M, Samuel F H. Porosity and the fatigue behavior of hypoeutectic and hypereutectic aluminum-silicon casting alloys [J]. International Journal of Fatigue, 2008, 30(6): 1024.
[22] Wang L, Fan X Y, Luo L S, Xu J G, Chen R R, Yi H Y, Zhou G Z, Wang N, Zhang J B, Su Y Q. Influence of traveling magnetic field on solidification defects and mechanical properties of ZL205A alloy sheet casts [J]. Rare Metal Materials and Engineering, 2016, 45(12): 3177.(王亮, 范学燚, 骆良顺, 许纪刚, 陈瑞润, 伊洪勇, 周国柱, 王宁, 张建兵, 苏彦庆. 行波磁场对ZL205A合金薄壁铸件凝固缺陷和力学性能的影响 [J]. 稀有金属材料与工程, 2016, 45(12): 3177.)