Enhancement of impact toughness properties of Al 7075 alloy via double aging heat treatment

Öz

In this study, Charpy impact test specimens were prepared by cutting Al 7075 alloy according to ASTM-E23 standards. The prepared test specimens were dissolved in a single-phase region for 1 hour at 480°C in vacuum atmosphere and artificially aged at 120°C for 24 hours after quenching. After the first step aging heat treatment applied, the specimens were artificially aged for 5-50 hours at 180°C for the second time. Microstructural characterization and fracture surface analyzes of the specimens were determined using SEM (Scanning Electron Microscope) device, crystallographic analysis of the precipitated phases were determined using XRD (X-ray diffraction) device. The increase in the amount of ƞı phase (MgZn2) with increasing double aging heat treatment time was effective in increasing the strength. After 10 hours of double aging heat treatment, the impact toughness value is improved by 300% compared to the single aged condition.

Anahtar Kelimeler

• Al 7075
• double aging
• microstructure
• Xrd analysis
• impact toughness

Kaynakça

1. [1] Han, N. M., et al. "Effect of solution treatment on the strength and fracture toughness of aluminum alloy 7050." Journal of Alloys and Compounds 509.10 (2011): 4138-4145.
2. [2] Altuntaş, Gözde, and Bülent Bostan. "Al–Zn–Mg–Cu Alaşımının Kristalografisine RRA Isıl İşlemi Etkilerinin İncelenmesi." Politeknik Dergisi: 1-1.
3. [3] Mondolfo, Lucio F. Aluminum alloys: structure and properties. Elsevier, 2013.
4. [4] Karakoyun, F., D. Kiritsis, and K. Martinsen. "Holistic life cycle approach for lightweight automotive components." Metallurgical Research & Technology 111.3 (2014): 137-146.
5. [5] Ma, Wenyu, et al. "Influence of solution heat treatment on mechanical response and fracture behaviour of aluminium alloy sheets: an experimental study." Materials & Design 88 (2015): 1119-1126.
6. [6] Ozer, A.,“The microstructures and mechanical properties of Al-15Si-2.5 Cu-0.5 Mg/(wt%) B4C composites produced through hot pressing technique and subjected to hot extrusion, Materials Chemistry and Physics, 183, 288-296. (2016).
7. [7] Srinivasan, Nedunchezhian, et al. "The role of brass texture on the deformation response of 7075-T651 aluminum alloy under equi-biaxial tension." Materials Science and Engineering: A 812 (2021): 141133.
8. [8] Aksöz, S., & Bostan, B., “Effects of ageing and cryoageing treatments on microstructure and hardness properties of AA2014–SiC MMCs” Transactions of the Indian Institute of Metals, 71(8), 2035-2042, (2018).

9. [9] Altuntaş, Gözde, Onur Altuntaş, and Bülent Bostan. "Characterization of Al-7075/T651 Alloy by RRA Heat Treatment and Different Pre-deformation Effects." Transactions of the Indian Institute of Metals 74.12 (2021): 3025-3033.
10. [10] Kaplan, Yavuz, et al. "The effect of aging processes on tribo-metallurgy properties of Al based ternary Alloys product by P/M technique." Science of Sintering 52.4 (2020).
11. [11] Berg, L. K., et al. "GP-zones in Al–Zn–Mg alloys and their role in artificial aging." Acta Materialia 49.17 (2001): 3443-3451.
12. [12] Song, R. G., and Q. Z. Zhang. "Heat Treatment Optimization For 7175 Aluminum Alloy By Genetic Algorithm." Materials Science and Engineering: C 17.1-2 (2001): 133-137.
13. [123 Liu, J. Z., et al. "Revisiting The Precipitation Sequence İn Al–Zn–Mg-Based Alloys By High-Resolution Transmission Electron Microscopy." Scripta Materialia 63.11 (2010): 1061-1064.
14. [14] Zhou, Pu, et al. "Mechanical Behavior And Deformation Mechanism Of 7075 Aluminum Alloy Under Solution İnduced Dynamic Strain Aging." Materials Science and Engineering: A 759 (2019): 498-505.
15. [15] Fan, Yun, et al. "Comparisons of Age Hardening and Precipitation Behavior in 7075 Alloy Under Single and Double-Stage Aging Treatments." Metals and Materials International 27.10 (2021): 4204-4215.
16. [16] Cai, S. W., Y. He, and R. G. Song. "Study on the Strengthening Mechanism of Two-Stage Double-Peaks Aging in 7075 Aluminum Alloy." Transactions of the Indian Institute of Metals 73.1 (2020): 109-117.
17. [17] Emani, S. V., et al. "Double aging and thermomechanical heat treatment of AA7075 aluminum alloy extrusions." Journal of materials science 44.23 (2009): 6384-6391.
18. [18] Kverneland, A., et al. "Transformations and structures in the Al–Zn–Mg alloy system: A diffraction study using synchrotron radiation and electron precession." Materials Science and Engineering: A 528.3 (2011): 880-887.
19. [19] Lechner, Wolfgang, et al. "Microstructure and vacancy-type defects in high-pressure torsion deformed Al–Cu–Mg–Mn alloy." Scripta materialia 61.4 (2009): 383-386.
20. [20] Dai, Pan, et al. "Nano-scale precipitate evolution and mechanical properties of 7085 aluminum alloy during thermal exposure." Materials Science and Engineering: A 729 (2018): 411-422.
21. [21] Harkness, S. D., and J. J. Hren. "An investigation of strengthening by spherical coherent GP Zones." Metallurgical Transactions 1.1 (1970): 43-49.
22. [22] Osamura, K., et al. "Structure of GP zones in an Al-1.7 at.% Cu alloy aged for 14 years at room temperature." Acta Metallurgica 31.10 (1983): 1669-1673.
23. [23] Liu, Siliang, et al. "On the atomic model of Guinier-Preston zones in Al-Mg-Si-Cu alloys." Journal of Alloys and Compounds 745 (2018): 644-650.
24. [24] Jiang, Jufu, et al. "Comparison of microstructural evolution of 7075 aluminum alloy fabricated by SIMA and RAP." Journal of Materials Processing Technology 238 (2016): 361-372.
25. [25] Fu, Jin-Long, Hong-Jun Jiang, and Kai-Kun Wang. "Influence of processing parameters on microstructural evolution and tensile properties for 7075 Al alloy prepared by an ECAP-based SIMA process." Acta Metallurgica Sinica (English Letters) 31.4 (2018): 337-350.
26. [26] Higgins R A, The Properties of Engineering Materials, Industrial Press Inc. (1994).
27. [27] Putra, Ichsan S., and Jaap Schijve. "Crack opening stress measurements of surface cracks in 7075‐T6 aluminium alloy plate specimen through electron fractography." Fatigue & Fracture of Engineering Materials & Structures 15.4 (1992): 323-338.
28. [28] Mo, Taiqian, et al. "Enhancing of mechanical properties of rolled 1100/7075 Al alloys laminated metal composite by thermomechanical treatments." Materials Science and Engineering: A 800 (2021): 140313.
29. [29] Krishna, N. Naga, et al. "Mechanical anisotropy and microstructural changes during cryorolling of Al–Mg–Si alloy." Materials Characterization 107 (2015): 302-308.
30. [30] Liu, Yan, et al. "Heating aging behavior of Al–8.35 Zn–2.5 Mg–2.25 Cu alloy." Materials & Design 60 (2014): 116-124.