Investigation of the Effects of Cold Forming Applied to AA 2024-T3 Materials on T8 Heat Treatment

Öz

The use of aluminum alloys in the aviation and space industry has an important place. Among these materials, AA2024 alloy is used especially in the main fuselage and beams of aircraft, as well as in connection and rivet materials. Since the strength of these alloys is low in their non-heat-treated form, the materials are strengthened by cold forming and heat treatment processes. In this study, AA2024-T3 materials were cold formed at room temperature at 30°, 45°, 60°, 75° and 90° angles and heat treatment were applied in order to bring them to T8 condition. The properties of the materials were examined in both T3 heat treatment condition and T8 condition after heat treatment. The microstructures of the alloys were examined with both optical and scanning electron microscopes. In addition, the changes in the microhardness and electrical conductivity properties of the alloys were also investigated. In the T3 materials that underwent the forming process, an increase in the average grain size occurred as the forming angle increased. In addition, a slight increase in the hardness values was also achieved. In the analyses performed on the materials in the T8 heat treatment condition, homogeneous grain sizes independent of form and high hardness values were obtained. In the microstructure analyses in the T8 heat treatment condition, it was observed that twin structures were formed between the grains.

Anahtar Kelimeler

• Cold Forming
• AA2024
• Heat Treatment
• Microstructure
• Hardness

AA 2024-T3 Malzemelere Uygulanan Soğuk Şekillendirmenin T8 Isıl İşlemine Olan Etkilerinin İncelenmesi

Öz

Havacılık ve uzay endüstrisinde alüminyum alaşımlarının kullanımı önemli bir yer tutmaktadır. Bu malzemelerden AA2024 alaşımı, özellikle uçakların ana gövde ve kirişlerinde, bağlantı ve perçin malzemelerinde kullanılmaktadır. Bu alaşımların ısıl işlem uygulanmamış haliyle mukavemetleri düşük olduğu için, soğuk şekillendirme ve ısıl işlem prosesleri ile malzemelere mukavemet kazandırılmaktadır. Bu çalışmada, AA2024-T3 malzemelere oda sıcaklığında 30°, 45°, 60°, 75° ve 90°’lik açılarında soğuk şekillendirme yapılıp, T8 ısıl işlem koşuluna getirmek amacıyla ısıl işlem uygulanmıştır. Malzemelerin özellikleri hem T3 ısıl işlem koşulunda hem de ısıl işlem sonrası T8 koşulunda incelenmiştir. Alaşımların mikroyapıları hem optik hem de taramalı elektron mikroskopları ile incelenmiştir. Ayrıca, alaşımların mikrosertlik ve elektriksel iletkenlik özelliklerindeki değişimleri de araştırılmıştır. Form işlemi yapılmış T3 malzemelerde form açısı arttıkça ortalama tane boyutunda artış meydana gelmiştir. Ayrıca, sertlik değerlerinde de bir miktar artış sağlanmıştır. T8 ısıl işlem koşulundaki malzemelerde yapılan analizlerde ise form açısından bağımsız homojen tane boyutları ve yüksek sertlik değerleri elde edilmiştir. T8 ısıl işlem koşulundaki mikroyapı analizlerinde tanelerde ikizlenme yapılarının oluştuğu gözlenmiştir.

Anahtar Kelimeler

• Soğuk İşlem
• AA2024
• Isıl İşlem
• Mikroyapı
• Sertlik

Kaynakça

1. Ç. Batuk, H. Demirtaş, Sürtünme Karıştırma Kaynağı ile Birleştirilmiş 6061 Alüminyum Alaşımlı Sacların Mekanik Özellikler Yönünden İncelenmesi, İmalat Teknolojileri ve Uygulamaları, 4(3):167–178, 2023.
2. Y.M. Khalid, R. Umer, K.A. Khan, Review of recent trends and developments in aluminium 7075 alloy and its metal matrix composites (MMCs) for aircraft applications, Results in Engineering, 20(101372), 2023.
3. P. Susmitha, S.V. Kumar, A critical review on the effect of various sustainable reinforcements on armor grade aluminum alloys, Materials Today: Proceedings, 03(039), 2024.
4. G. Liu, Y. Ren, W. Ma, K. Morita, Y. Lei, S. Zhan, S. Li, Z. Wang, R. Li, Recent advances and future trend of aluminum alloy melt purification: A review, J. Mater. Res. Technol., 28:4647–4662, 2024.
5. L.Y. Zhao, Q.Z. Yang, Z. Zhang Z, G. Su, L.X. Ma, Double-peak age strengthening of cold-worked 2024 aluminum alloy Acta Mater.,61: 1624–1638, 2013.
6. A.E. Starke, Aluminum alloys: alloy, heat treatment, and temper designation, Encyclopedia of Materials: Science and Technology, 106-107, 2001.
7. H.A. Rashed, A.M. Rashid, Heat Treatment of Aluminum Alloys, Comprehensive Materials Finishing, 2:337–371, 2017.
8. A. Jaafar, A. Rahmat, Z. Hussain, I. Zainol, Effect of Mg, Si and Cu content on the microstructure of dilute 6000 series aluminium alloys, Journal of Alloys and Compounds, 509:8632–8640, 2011.

9. K.A. Gupta, J.D. Lloyd, A.S. Court, Precipitation hardening in Al–Mg–Si alloys with and without excess Si, Materials Science and Engineering: A, 316(2):11–17, 2001.
10. R.O. Myhr, T. Borvik, D.C. Marioara, S.Wenner, S.O. Hopperstad, Nanoscale modelling of combined isotropic and kinematic hardening of 6000 series aluminium alloys, Mech. Mater., 151(103603), 2020.
11. J.A. Tomstad, S. Thomesen, T. Borvik, S.O. Hopperstad, Effects of constituent particle content on ductile fracture in isotropic and anisotropic 6000-series aluminium alloys, Materials Science and Engineering: A, 820(141420), 2021.
12. R.M. Langille, J.B. Diak, F. De Geuser, A. Deschamps, G. Guiglionda, Asymmetry of strain rate sensitivity between up- and down-changes in 6000 series aluminium alloys of varying Si content, Materials Science and Engineering: A, 788(139517), 2020.
13. T. Rahmaan, C. Butcher, S. Kim, J.M. Worswick, Characterization and prediction of fracture in 6000- and 7000-series aluminum alloy sheet under various stress states, Thin-Walled Struct. 173(108958), 2022.
14. K. Omer, C. Butcher, M. Worswick, Characterization and application of a constitutive model for two 7000-series aluminum alloys subjected to hot forming, Int. J. Mech. Sci., 165(105218), 2020.
15. P. Bamberg, G. Gintrowski, Z. Liang, A. Schiebahn, U. Reisgen, N. Precoma, C. Geffers, Development of a new approach to resistance spot weld AW-7075 aluminum alloys for structural applications: an experimental study – Part 1, J. Mater. Res. Technol., 15: 5569–5581, 2021.
16. H.A. Siddiqui, P. Tiwari, P.J. Patil, A. Tewari, S. Mishra, Yield locus and texture evolution of AA7475-T761 aluminum alloy under planar biaxial loading: An experimental and analytical study, J. Alloys Compd., 1000(175115), 2024.
17. A. Shahsavari, F. Karimzadeh, A. Rezaeian, H. Heydari, Significant Increase in Tensile Strength and Hardness in 2024 Aluminum Alloy by Cryogenic Rolling, Procedia Mater. Sci., 11:84–88, 2015.
18. D. Bakavos, B.P. Prangnell, B. Bes, F. Eberl, The effect of silver on microstructural evolution in two 2xxx series Al-alloys with a high Cu:Mg ratio during ageing to a T8 temper, Materials Science and Engineering: A, 491: 214–223, 2008.
19. X. Tao, Y. Gao, Effects of wet shot peening on microstructures and mechanical properties of a 2060-T8 aluminum-lithium alloy, Materials Science and Engineering: A, 832(142436), 2022.
20. H. Li, Y.Tang, Z. Zeng, F. Zheng, Exfoliation corrosion of T6- and T8-aged AlxCuyLiz alloy, Trans. Nonferrous Met. Soc. China, 18:778–783, 2008.
21. H.M. Goodarzy, H. Arabi, A.M Boutorabi, H.S. Seyedein, S.H Najafabadi, The effects of room temperature ECAP and subsequent aging on mechanical properties of 2024 Al alloy, Journal of Alloys and Compounds, 585:753–759, 2014.
22. P. Wang, L. Ye, Y. Deng, Z. Guo, Y. Zhang, Z. Shen, Y. Xu, Enhanced fatigue crack propagation resistance of a new Al–Cu–Li alloy via different aging processes, J. Mater. Res. Technol., 30:5368–5380, 2024.
23. G. Mrowka, J Sieniawski, Analysis of Intermetallic Phases in 2024 Aluminum Alloy, Solid State Phenomena, 197:238–243, 2013.
24. J. Xu, X. Zhu, D. Shan, B. Guo, T. Langdon, Effect of grain size and specimen dimensions on micro-forming of high purity aluminum, Materials Science and Engineering: A, 646:207–217, 2015.
25. S. Sabari, G.D. Andrade, C. Leitão, F. Simões, M.D. Rodrigues, Influence of the strain hardening behaviour on the tensile and compressive response of aluminium auxetic structures, Composite Structures, 305(116472), 2023.
26. G. Zhang, Z. Zhu, J. Ning, C. Feng, Dynamic impact constitutive relation of 6008-T6 aluminum alloy based on dislocation density and second-phase particle strengthening effects, Journal of Alloys and Compounds, 932(167718), 2023.
27. X. Jia, R.M. Su, W.J Zhang, L. Li, Y. Quand, D.R. Li, Effect of Cold-Drawing Deformation on the Microstructure and Properties of AA2024-T8, Physics of Metals and Metallography, 124:1501–1508, 2024.
28. J. Chen, Y. Ding, X. Zhang, Y. Gao, Y. Ma, Intrinsic stacking fault energy and mechanism for deformation twin formation of solid solution matrix in Ni-based superalloys, Vacuum, 203(11132), 2022.
29. B. Guo, M. Song, X. Zhang, Y. Liu, X. Cen, B. Chen, W. Li, Exploiting the synergic strengthening effects of stacking faults in carbon nanotubes reinforced aluminum matrix composites for enhanced mechanical properties, Composites Part B: Engineering, 211(108646), 2021.