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Research Papers

Effect of Cooling Rate on Mechanical Properties of 7075 Aluminum Rods Extruded in Semisolid State

[+] Author and Article Information
Mostafa Ketabchi

Department of Mining and Metallurgy,
Amirkabir University of Technology,
424 Hafez Avenue,
Tehran 15875-4413, Iran
e-mail: ketabchi@aut.ac.ir

Mohammad Amin Shafaat

Department of Mining and Metallurgy,
Amirkabir University of Technology,
424 Hafez Avenue,
Tehran 15875-4413, Iran
e-mail: ma_shafaat@aut.ac.ir

Iman Shafaat

BINAS Co.,
P.O. Box 14665-943,
Tehran 1468863331, Iran
e-mail: i.shafaat@binusco.com

Mahmoud Abbasi

Faculty of Engineering,
University of Kashan,
Ravandi Highway,
Kashan 8731751167, Iran
e-mail: m.abbasi@aut.ac.ir

Contributed by the Materials Division of ASME for publication in the JOURNAL OF ENGINEERING MATERIALS AND TECHNOLOGY. Manuscript received November 15, 2012; final manuscript received December 4, 2013; published online January 17, 2014. Assoc. Editor: Ashraf Bastawros.

J. Eng. Mater. Technol 136(2), 021002 (Jan 17, 2014) (8 pages) Paper No: MATS-12-1257; doi: 10.1115/1.4026193 History: Received November 15, 2012; Revised December 04, 2013

Semisolid extrusion of metals involves extrusion of metallic alloys with a microstructure consisting of spherical solids in a liquid matrix. In this research, the effect of cooling rate during forward semisolid extrusion on microstructure and mechanical properties of 7075 aluminum was investigated. Semisolid microstructure was prepared according to the recrystallization and partial melting (RAP) method. Optimum semisolid temperature and holding time which were resulted in a suitable microstructure for specimens were determined at 580 °C for 10 min. Different cooling rates were applied during semisolid extrusion and the resulted mechanical properties were studied. Tensile properties of semisolid extruded rods in T6 condition were also compared with those of conventionally extruded specimen. The results indicate that utilizing optimum values of semisolid extrusion parameters, namely, temperature and time of heating as well as cooling rate severity, brings both the possibility to obtain mechanical properties of conventionally extruded specimens and to get advantages of semisolid forming technique. Experimental results also show that increment of cooling rate and extrusion pressure improves the mechanical properties.

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References

Fan, Z., 2002, “Semisolid Metal Processing,” Int. Mater. Rev., 47, pp. 49–84. [CrossRef]
Dong, J., Cui, J. Z., Le, Q. C., and Lu, G. M., 2003, “Liquidus Semi-Continuous Casting, Reheating and Thixoforming of a Wrought Aluminum Alloy 7075,” Mater. Sci. Eng., A, 345, pp. 234–242. [CrossRef]
Kliauga, A. M., and Ferrante, M., 2005, “Liquid Formation and Micro Structural Evolution During Re-Heating and Partial Melting of an Extruded A356 Aluminum Alloy,” Acta Mater., 53, pp. 345–356. [CrossRef]
Atkinson, H. V., Burke, K., and Vaneetveld, G., 2008, “Recrystallisation in the Semi-Solid State in 7075 Aluminum Alloy,” Mater. Sci. Eng., A, 490, pp. 266–276. [CrossRef]
Kim, S. K., Yoon, Y. Y., and Jo, H. H., 2007, “Novel Thixoextrusion Process for Al Wrought Alloy,” J. Mater. Process. Technol., 187–188, pp. 354–357. [CrossRef]
Flemings, M. C., 2000, “Semi-Solid Forming: The Process and the Path Forward,” Metall. Sci. Technol., 18, pp. 3–4, http://www.teksid.com/science-1.htm
Dazhi, Z., Guimin, L., and Jianzhong, C., 2008, “Semi-Solid Extrusion of Aluminium Alloy ZL116,” China Foundry, 5, pp. 104–109, http://www.doaj.org/doaj?func=issueTOC&isId=130870&uiLanguage=en
Chayong, S., Atkinson, H. V., and Kapranos, P., 2005, “Thixoforming 7075 Aluminum Alloys,” Mater. Sci. Eng., A, 390, pp. 3–12. [CrossRef]
Birol, Y., 2011, “Response to T6 Heat Treatment of Extruded and Thixoformed En Aw 2014 Alloys,” Mater. Sci. Eng., A, 528, pp. 5636–5641. [CrossRef]
ASTM, 2000, “Standard Test Methods of Tension Testing of Metallic Materials [Metric],” Annual Book of ASTM Standards, Vol. 3.01, American Society for Testing and Materials [CrossRef]. West Conshohocken, PA, Standard No. E8M00b.
Hertzberg, R. W., 1996, Deformation and Fracture Mechanics of Engineering Materials, John Wiley and Sons Inc., New York.
Humphreys, F. J., and Hatherly, M., 2004, Recrystallization and Related Annealing Phenomena, Elsevier, Kidlington, Oxford, UK.
Doherty, R. D., Hughes, D. A., Humphreys, F. J., Jonas, J. J., Jensen, D. J., Kassner, M. E., King, W. E., McNelley, T. R., McQueen, H. J., and Rollett, A. D., 1997, “Current Issues in Recrystallization: A Review,” Mater. Sci. Eng., A, 238, pp. 219–274. [CrossRef]
Atkinson, H. V., Burke, K., and Vaneetveld, G., 2008, “Recrystallistion in the Semi-Solid State in 7075 Aluminum Alloy,” Mater. Sci. Eng., A, 490, pp. 266–276. [CrossRef]
Dehoff, R. T., 1993, Capillarity Effects in Thermodynamics, Thermodynamics in Materials Science, McGraw-Hill, Singapore, pp. 355–404.
Bocquet, J. L., Brebec, G., and Lwioge, Y., 1996, “Diffusion in Metals and Alloys,” Physical Metallurgy, Vol. 1, R. W.Cahn, and P.Haasen, eds., Elsevier Science, Amsterdam, pp. 535–668.
Bünck, M., Küthe, F., and Bührig-Polaczek, A., 2009, “Rheocasting of Aluminium Alloys and Thixocasting of Steels,” Thixoforming: Semi-Solid Metal Processing, G.Hirt, and R.Kopp, eds., Wiley-VCH Verlag GmbH & Co., Weinheim, Germany, pp. 311–368. [CrossRef]
Nami, B., Shabestari, S. G., Razavi, H., Mirdamadi, S., and Miresmaeili, S. M., 2011, “Effect of Ca, RE Elements and Semi-Solid Processing on the Microstructure and Creep Properties of AZ91 Alloy,” Mater. Sci. Eng., A, 528, pp. 1261–1267. [CrossRef]
Reed-Hill, R. E., and Abbaschian, R., 1994, Physical Metallurgy Principles, PWS Publishing Co., Boston.
Atkinson, H. V., and D. L., 2008, “Microstructural Coarsening of Semi-Solid Aluminum Alloys,” Mater. Sci. Eng., A, 496, pp. 439–446. [CrossRef]
Tzimas, E., and Zavaliangos, A., 2000, “Evolution of Near-Equiaxed Microstructure in the Semisolid State,” Mater. Sci. Eng., A, 289, pp. 228–240. [CrossRef]
Meyers, M. A., and Chawla, K. K., 1984, Mechanical Metallurgy: Principles and Applications, Prentice-Hall, Englewood Cliffs, NJ.
Altan, T., Oh, S.-I., and Gegel, H. L., 1993, “Conventional Hot Extrusions,” Metals Handbook, Vol. 14—Forming and Forging, 9th ed., S. L.Semiatin, ed., ASM International, Materials Park, OH, pp. 315–326.
Cho, W. G., and Kang, C. G., 2000, “Mechanical Properties and Their Microstructure Evaluation in the Thixoforming Process of Semi-Solid Aluminum Alloys,” J. Mater. Process. Technol., 105, pp. 269–277. [CrossRef]
Guo, H.-M., Yang, X.-J., and Zhang, M., 2008, “Microstructure Characteristics and Mechanical Properties of Rheoformed Wrought Aluminum Alloy 2024,” Trans. Nonferrous Met. Soc. China, 18, pp. 555–561. [CrossRef]
Liu, D., Atkinson, H. V., Kapranos, P., Jirattiticharoean, W., and Jones, H., 2003, “Microstructural Evolution and Tensile Mechanical Properties of Thixoformed High Performance Aluminum Alloys,” Mater. Sci. Eng., A, 361, pp. 213–224. [CrossRef]
Bergsma, S. C., Li, X., and Kassner, M. E., 2001, “Semi-Solid Thermal Transformations in Al-Si Alloys: II. The Optimized Tensile and Fatigue Properties of Semi-Solid 357 and Modified 319 Aluminum Alloys,” Mater. Sci. Eng., A, 297, pp. 69–77. [CrossRef]
Du, X., and Zhang, E., 2007, “Microstructure and Mechanical Behavior of Semi-Solid Die-Casting AZ91d Magnesium Alloy,” Mater. Lett., 61, pp. 2333–2337. [CrossRef]
Vieira, E. A., and Ferrante, M., 2005, “Prediction of Rheological Behavior and Segregation Susceptibility of Semi-Solid Aluminum-Silicon Alloys by a Simple Back Extrusion Test,” Acta Mater., 53, pp. 5379–5386. [CrossRef]
Kiuchi, M., and Sugiyama, S., 1994, “Mushy State Extrusion, Rolling and Forging,” 3rd International Conference on Semi-Solid Processing of Alloys and Composites, Tokyo, Japan, June 13–15, pp. 245–257.
Witulski, T., Heuβen, J. M. M., Winkelmann, A., Hirt, G., and Kopp, R., 1994, “Near Net Shape Forming of Particulate Reinforced Al-Alloys by Isothermal Forming Compared to Semi Solid Forming,” J. Mater. Process. Technol., 45, pp. 415–420. [CrossRef]
Kopp, R., Mertens, H.-P., Wimmer, M., Winning, G., and Witulski, N., 1998, “Thixoextrusion of Aluminium Alloys,” 5th International Conference on Semi-Solid Processing of Alloys and Composites, Golden, CO, June 23–25, pp. 283–289.

Figures

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Fig. 1

Different methods of semisolid microstracture preparation

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Fig. 2

Liquid fraction versus temperature obtained in constant heating rate of 10 °C/min

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Fig. 3

The apparatus used for semisolid extrusion

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Fig. 4

Dimensions of the round, subsized tension test specimens according to the ASTM-E8 standard specifications [10]

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Fig. 5

Optical micrograph of warm extruded specimen along ED before heating to semisolid temperature. Arrows indicate instances of elongated grains and strings of intermetallic particles.

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Fig. 6

Microstructures of the 7075 alloy after heating at different semisolid temperatures for 10 min and 20 min

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Fig. 7

Results of quantitative study of semisolid microstructures holded at different tempratures for 10 min and 20 min: (a) average grain size and (b) shape factor

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Fig. 8

Semisolid extrusion pressure versus the length of the semisolid extruded rod

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Fig. 9

Schematic representation of the load-stroke diagram for conventional forward and backward extrusion [23]

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Fig. 10

Macro-etched cross section of unextruded billets within the die cavity for semisolid extrusion performed under pressure of 23 MPa (a) and 33 MPa (b). In the chilled part, where the material was solidified due to operating the cooling system, dynamically recrystallized (DRX) grains are observable.

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Fig. 11

Comparison of tensile strength (UTS), yield stress (YS), and elongation to fracture (El%) of four groups of specimens listed in Table 3

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Fig. 12

SEM image of fracture surface of the tension test specimen with globular microstructure (Group A)

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Fig. 13

Transverse (a) and longitudinal (b) sections of the fracture surface for the specimen extruded with the extrusion presure of 23 MPa (Group B)

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Fig. 14

Fracture surfaces of extruded specimens: (a) semisolid extruded at 23 MPa (Group B), (b) semisolid extruded at 23 MPa (Group C), and (c) conventionally warm extruded (Group D)

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