Microstructure as an essential aspect of EN AW 7075 aluminum alloy quality influenced by electromagnetic field during continuous casting process

Aleksandra Patarić, Marija Mihailović, Branislav Marković, Miroslav Sokić, Andreja Radovanović, Branka Jordović

Abstract


Microstructure assessment is crucial for the design and production of high-quality alloys such as cast aluminum alloy ingots. Along with the effect of a more homogeneous microstructure to result in much better mechanical properties, better as-cast alloy quality indicates a higher efficiency of the aluminum alloys production process. During the aluminum alloy solidification process many microstructural defects can occur, which deteriorate the mechanical properties and hence decrease the usability of such an ingot. Application of the electromagnetic field during the vertical continuous casting process significantly reduces occurrence of these defects. In the present study, EN AW 7075 alloy samples were cast with and without application of an electromagnetic field and examined regarding the microstructure, electrical conductivity, and changes in the phase composition. The obtained results clearly show that it is possible to decrease or avoid casting defects by the electromagnetic field application as verified by the microstructure characterization and quantification, electrical conductivity tests and differential thermal analysis (DTA).


Keywords


microstructure assessment; DTA analysis; electrical conductivity; EN AW 7075 alloy

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References


Cao Z, Jia F, Zhang X, Hao H, Jin J. Microstructures and mechanical characteristics of electromagnetic casting and direct-chill casting 2024 aluminum alloys. Mater Sci Eng A. 2002; 327: 133-137. https://doi.org/10.1016/S0921-5093(01)01673-2

Dong J, Cui J, Yu F, Ban C, Zhao Z. Effect of low-frequency electromagnetic casting on the castability, microstructure and tensile properties of direct –chill cast Al-Zn-Mg-Cu alloy. Metall Mater Trans A. 2004; 35: 2487-2494. https://doi.org/10.1007/s11661-006-0228-2

Zhang B, Lu G, Cut J. Effect of Electromagnetic Frequency on Microstructures of Continuous Casting Aluminum Alloys. J Mater Sci Technol. 2002; 118: 401-403. https://doi.org/10.3321/j.issn:1005-0302.2002.05.006

Cui J, Zhang Z, Le Q. DC casting of light alloys under magnetic fields. Trans Nonferrous Met Soc China. 2010; 20: 2046-2050. https://doi.org/10.1016/S1003-6326(09)60415-5

Zhang H, Nagaumi H, Zuo Y, Cui J. Coupled modeling of electromagnetic field, fluid flow, heat transfer and solidification during low frequency electromagnetic casting of 7XXX aluminum alloys: Part 1: Development of a mathematical model and comparison with experimental results. Mater Sci. Eng A. 2007; 448: 189-203. https://doi.org/10.1016/j.msea.2006.10.062

Zhao Z, Cui J, Dong J, Wang Z, Zhang B. Effect of low-frequency magnetic field on microstructures of horizontal direct chill casting 2024 aluminium alloy. J Alloy Com. 2005; 396: 164-168. https://doi.org/10.1016/j.jallcom.2004.12.020

Hao H, Zhang X, Park J, Kim H, Jin J. Twin-strand technology and microstructure analysis for the electromagnetic near net-shape casting of aluminum alloy. J Mater Process Technol. 2003; 142: 526-531. https://doi.org/10.1016/S0924-0136(03)00653-8

Mapelli C, Gruttadauria A, Peroni M. Application of electromagnetic stirring for the homogenization of aluminium billet cast in a semi-continuous machine. J Mater Process Technol. 2010; 314: 306-314. https://doi.org/10.1016/j.jmatprotec.2009.09.016

Zuo Y, Cui J, Dong J, Yu F. Effect of low frequency electromagnetic field on the constituents of a new super high strength aluminium alloy. J Alloy Compd. 2005; 402: 149-155. https://doi.org/10.1016/j.jallcom.2005.04.135

Zuo Y, Cui J, Dong J, Yu F. Effects of low frequency electromagnetic field on the as-cast microstructures and mechanical properties of superhigh strength aluminum alloy. Mater Sci Eng. 2005; 408: 176-181. https://doi.org/10.1016/¬j.msea.2005.-07.030

Zuo Y, Cui J, Zhao Z, Zhang H, Qin K. Effect of low frequency electromagnetic field on casting crack during DC casting superhigh strength aluminum alloy ingots. Mater Sci Eng. 2005; 406: 286-292. https://doi.org/10.1016/j.msea.2005.07.001

Prodhan A, Sivaramakrishnan CS, Chakrabarti AK. Solidification of aluminum in electric field. Metall Mater Trans B. 2001; 32: 372-378. https://doi.org/10.1007/s11663-001-0060-4

Hao H, Zhang X, Yao S, Jin J. Improvement of Casting Speed and Billet Quality of Direct Chill Cast Aluminum Wrought Alloy with Combination of Slit Mold and Electromagnetic Coil. Mater Trans. 2007; 48: 2194-2201. DOI: 10.2320/matertrans.MRA2007030

Cui J, Zhang Z, Le Q. Direct-chilling casting of Mg alloy under electromagnetic and ultrasonic combined field. Trans Nonferrous Met Soc China. 2010; 20: 297-305. https://doi.org/10.1016/S1003-6326(10)60487-6

Wang G, Zhao Z, Guo Q, Cui J. Effect of homogenizing treatment on microstructure and conductivity of 7075 aluminum alloy prepared by low frequency electromagnetic casting. China Foundry. 2014; 11: 39-45. http://www.foundryworld.com/-uploadfile/2014022660542305.pdf

Dong J, Cui J, Ding W. Theoretical discussion of the effect of a low-frequency electromagnetic vibrating field on the as-cast microstructures of DC Al–Zn–Mg–Cu–Zr ingots. J Cryst Growth 2006; 295: 179-187. https://doi.org/10.1016/j.jcrysgro.2006.-07.025

Radjai A, Miwa K. Effects of the intensity and frequency of electromagnetic vibrations on the microstructural refinement of hypoeutectic Al-Si alloys. Metall Mater Trans A. 2000; 31: 755-762. https://doi.org/10.1007/s11661-000-0017-2

Chen G, Li J, Yin Z, Xu G. Improvement of microstructure and properties in twin-roll casting 7075 sheet by lower casting speed and compound field. Mater Charact. 2017; 127: 325-332. https://doi.org/10.1016/j.matchar.2017.03.024

Jeshvaghani R, Zohdi H, Shahverdi H, Bozorg M, Hadavi S. Influence of multi-step heat treatments in creep age forming of 7075 aluminum alloy: Optimization for springback, strength and exfoliation corrosion. Mater Charact. 2012; 73: 8-15. https://doi.org/10.1016/j.matchar.2012.05.012

Patarić A, Gulišija Z, Marković S. Microstructure Examination of Electromagnetic Casting 2024 Aluminum Alloy Ingots. Prakt Metallogr. 2007; 44: 290-298. https://doi.org/10.3139/147.100346

Patarić A, Mihailović M, Gulišija Z. Quantitative Metallographic Assessment of the Electromagnetic Casting Influence on the Microstructure of 7075 Al Alloy. J Mater Sci. 2012; 47: 793-796. https://doi.org/10.1007/s10853-011-5855-3

Mondolfo L. F. Aluminium Alloys: Structure and Properties, Boston, Butterworths, 1976.

Lee W, Bang K, Jung S Effects of intermetallic compound on the electrical and mechanical properties of friction welded Cu/Al bimetallic joints during annealing. J Alloy Compd. 2005; 390: 212-219. https://doi.org/10.1016/j.jallcom.2004.07.057




DOI: https://doi.org/10.2298/HEMIND201214006P

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