Al-Mg-Si系列鋁合金具有高比強度、高熱導性及良好的抗腐蝕性質，因近來節省能源議題受到重視而大量應用於交通運輸工具之零組件。6069鋁合金含有較高的Mg、Si、Cu含量，故本實驗以一階段及兩階段固溶熱處理，改變同鍛件中兩種不同熱鍛比部位之固溶條件，探討合金元素分布與拉伸性質。
　　實驗結果顯示，Disk部位經一階段固溶熱處理及兩階段固溶熱處理之T6材，因合金元素抑制晶粒成長，而使平均晶粒徑無明顯差異；在過高溫固溶熱處理下(570℃)T6材之金相，發現因熔融而形成較粗大的三元共晶相；而兩階段熱處理先施以較低固溶溫度(480℃)，再施以較高溫度(570℃)則無發現Al-Mg2Si-Si之三元共晶相之生成，且Cu元素在Al基地中有最均勻的分布。
　　拉伸性質方面，Disk部位經一階段固溶熱處理隨著固溶溫度提升，Mg2Si固溶量上升而使T6後析出強化效應更為明顯，使強度上升而延性稍降；在過高溫固溶處理之T6材，因硬脆的三元共晶相生成導致強度無法進一步提升且造成延性與韌性降低；兩階段固溶熱處理之T6材則因Cu均勻分布，且第二相之尖端圓鈍化效應，使強度、延性與韌性均有良好表現。
　　不同熱鍛比(不同部位)部分皆具鍛造組織外，Rim部位(高熱鍛比)仍具有殘留鑄造組織之金相，導致拉伸性質差於Disk部位(低熱鍛比)。而Rim部位施以兩階段固溶熱處理有效地使鑄造組織均質化，使拉伸強度高於一階段固溶熱處理。

6069 Al alloy is an Al-Mg-Si alloy which has high specific strength, thermo conductivity, good corrosion resistance and formability, and widely used in transport industry. This research study in distribution of alloy elements and tensile properties with various the T4 treatment and different hot forging ratio.
Results showed that the two-stepped solution heat treatment shows the more uniform distribution of Cu. 550 °C and two-stepped of T4 treatment have better tensile properties in disk part. In rim part, observation of casting feature is the defect which caused the tensile properties worse than disk part. And two-stepped T4 treatment has better properties than 500 °C due to the effect of homogenization.

1. K. Chen, H. Liu, Z. Zhang, S. Li, R. I. Todd, “The improvement of constituent dissolution and mechanical properties of 7055 aluminum alloy by stepped heat treatments”, Journal of Materials Processing Technology. Vol.142, pp.190-196, 2003.
2. G. Mrówka-Nowotnik, J. Sieniawski, “Influence of heat treatment on the microstructure and mechanical properties of 6005 and 6082 aluminium alloys”, Journal of Materials Processing Technology. Vol.162-163, pp.367-372, 2005.
3. A. Lise Dons, “The Alstruc homogenization model for industrial aluminum alloys”, Journal of Light Metals. Vol.1, pp.133-149, 2001.
4. 許源泉，「鍛造學: 理論與實習」，三民書局，第一章，1990年。
5. 林文樹，「鍛造學」，復文書局，第一章，2001年。
6. ASM International Handbook Committee, “Properties and selection : nonferrous alloys and special-purpose materials”, pp.51, 1990.
7. 村上陽太郎、龜井清，「非鐵金屬材料學」，朝倉書店，第76頁， 1978年。
8. J. E. Hatch, “Aluminum properties and physical metallurgy”, American Society for Metals, pp.224-240, 1984.
9. S. C. Bergsma, M. E. Kassner, X. Li, M. A. Delos-Reyesm, T. A. Hayes, “The optimized mechanical properties of the new aluminum alloy AA 6069”, Journal of Materials Engineering and Performance. Vol.5, pp.111-116, 1996.
10. P. Villars, A. Prince, H. Okamoto, “Handbook of ternary alloy phase diagrams”, pp.3903-3916, 1995.
11. J. Zhang, Y. Q. Wang, B. Yang, B. L. Zhou, “Effects of Si content on the microstructure and tensile strength of an in situ Al/Mg2Si composite”, Journal of materials research. Vol.14, pp.68-74, 1999.
12. L. Zhen, W. D. Fei, S. B. Kang, H. W. Kim, “Precipitation behaviour of Al-Mg-Si alloys with high silicon content”, Journal of Materials Science. Vol.32, pp, 1895, 1997.
13. J. R. Davis, “Aluminum and aluminum alloys”, ASM International., pp.90-92, 1993.
14. R. A. Jeniski Jr., “Effects of Cr addition on the microstructure and mechanical behavior of 6061-T6 continuously cast and rolled redraw rod”, Materials Science and Engineering A. Vol.237, pp.52-64, 1997.
15. S. R. Claves, D. L. Elias, W. Z. Misiolek, “Analysis of the Intermetallic Phase Transformation Occurring during Homogenization of 6xxx Aluminum Alloys”, Materials Science Forum. Vol.396-402, pp.667-674, 2002.
16. P. Sepehrband, R. Mahmudi, F. Khomamizadeh, “Effect of Zr addition on the aging behavior of A319 aluminum cast alloy”, Scripta Materialia. Vol.52, pp.253-257, 2005.
17. D. J. Chakrabarti, D. E. Laughlin, “Phase relations and precipitation in Al-Mg-Si alloys with Cu additions”, Progress in Materials Science. Vol.49, pp.389-410, 2004.
18. M. Murayama, K. Hono, W. F. Miao, D. E. Laughlin, “The effect of Cu additions on the precipitation kinetics in an Al-Mg-Si alloy with excess Si”, Metallurgical and Materials Transactions A. Vol.32, pp.239-246, 2001.
19. M. Cabibbo, E. Evangelista, C. Scalabroni, E. Bonetti, “A Transmission Electron Microscopy Study of the Role of Sc+Zr Addition to a 6082-T8 Alloy Subjected to Equal Channel Angular Pressing”, Materials Science Forum. Vol.503-504, pp.841-846, 2006.
20. S. C. Bergsma, M. E. Kassner, X. Li, M. A. Wall, “Strengthening in the new aluminum alloy AA 6069”, Materials Science and Engineering A. Vol.254, pp.112-118, 1998.
21. F. J. MacMaster, K. S. Chan, S. C. Bergsma, M. E. Kassner, “Aluminum alloy 6069 part II: fracture toughness of 6061-T6 and 6069-T6”, Materials Science and Engineering A. Vol.289, pp.54-59, 2000.
22. J. H. Sokolowski, M. B. Djurdjevic, C. A. Kierkus, D. O. Northwood, “Improvement of 319 aluminum alloy casting durability by high temperature solution treatment”, Journal of Materials Processing Technology. Vol.109, pp.174-180, 2001.
23. I. Aguilera Luna, H. Mancha Molinar, M. J. Castro Román, J. C. Escobedo Bocardo, M. Herrera Trejo, “Improvement of the tensile properties of an Al–Si–Cu–Mg aluminum industrial alloy by using multi stage solution heat treatments”, Materials Science and Engineering A. Vol.561, pp.1-6, 2013.
24. N. A. Belov, D. G. Eskin, A. A. Aksenov, “Multicomponent phase diagrams applications for commercial aluminum alloys”, Elsevier., pp.123-131, 2005.
25. N. A. Belov, A. V. Koltsov, D. G. Eskin, “The Al-Cu-Fe-Mg-Si Phase Diagram in the Range of Al-Cu Alloys”, MaterialsScience Forum. Vol.396/402, pp.929-934, 2002.
26. H. Toda, T. Nishimura, K. Uesugi, Y. Suzuki, M. Kobayashi, “Influence of high-temperature solution treatments on mechanical properties of an Al–Si–Cu aluminum alloy”, Acta Materialia. Vol.58, pp.2014-2025, 2010.
27. O. Reiso, N. Ryum, J. Strid, “Melting of secondary-phase particles in Al-Mg-Si alloys”, Metallurgical Transactions A. Vol.24, pp.2629-2641, 1993.
28. M. A. Azmah Hanim, S. Chang Chung, O. Khang Chuan, “Effect of a two-step solution heat treatment on the microstructure and mechanical properties of 332 aluminium silicon cast alloy”, Materials and Design. Vol.32, pp.2334-2338, 2011.