本論文係探討無錳元素之Al-Zn-Mg-Zr合金以ER5356銲條銲接後，求出最佳銲後熱處理參數。先以微硬度試驗、導電度量測，求出適用於Al-Zn-Mg-Zr銲件銲後熱處理之參數組合，再以金相觀察、拉伸試驗、X光能量散佈儀(EDS)、電子微探分析儀(EPMA)及掃描式電子顯微鏡(SEM)並探討銲件經銲後熱處理之機械性質影響及銲道與母材之間元素擴散情形。
研究結果顯示，Al-Zn-Mg-Zr合金銲件最佳銲後熱處理參數分冸是 T6：470℃/40min. + 80℃/14hr. + 120℃/27hr.; T7：470℃/40min. + 80℃/14hr. + 107℃/8hr.+168℃/12hr. ; RRA：T6 +180℃/20min.+ 120℃/27hr.。
銲後T6熱處理能大幅提升銲件硬度；銲後T7熱處理使銲件整體抗拉強度最高，且導電度最高，推論抗應力腐蝕能力較佳。銲後RRA熱處理銲件硬度值近似銲後T6熱處理，導電度則相近於銲後T7熱處理，顯示RRA熱處理可提高銲件強度與導電度。
由於ER5356銲條為非熱處理型鋁合金，可藉由適當的銲後熱處理，使母材之鋅元素有效地擴散至銲道內，藉此改變銲道內合金成份，增加銲道析出硬化之效果。在銲道內若其鋅、鎂總含量越多，且有較高的Mg/Zn比，於時效處理時能有更多機會形成MgZn2與Mg3Zn3Al2析出相，因此將可提高銲道硬度。

The objective of this study is to investigate the effect of post-welding heat c processes parameters on the mechanical properties of Mn-Free Al-Zn-Mg-Zr(G7F) weldment. Hardness test, electrical conductivity measurement were conducted to seek for the most suitable heat treatment combinations of process parameters for the T6, T7 and RRA treatment of Al-Mg-Zn-Zr(G7F) weldment. Optical metallographic observation, tensile test, EDS, EPMA and SEM, were conducted to characterize the mechanical properties of these heat-treated weldments.
Experimental results showed that the most suitable process parameters for T6 temper are 470℃/40min. + 80℃/14hr.+120℃/27hr.; for T7 temper are 470℃/40min.+80℃/14hr.+ 107℃/8hr. + 168℃/12hr. ; and for RRA treatment are T6 +180℃/20min.+ 120℃/27hr.。
Welds after T6 temper, weldment with the highest hardness；T7 temper is the most suitable post-weld heat treatment process to produce weldment with right characteristics and the best conductivity, show have best stress corrosion cracking resistance. Weldment after RRA treatment the handness is closed to that of T6 temper, and the conductivity is similar to that of the T7 temper, indicating post-welding RRA heat treatment can improve stress corrosion cracking resistance without the sacrifice of tensile strength.
Appropriate post-welding heat treatment processes parameters can diffuse zinc atoms effectively in the fusion zone. In such a way, the content of alloying elements composition within the fusion zone is change. There are more opportunities for Zn and Mg atoms to form MgZn2 and Mg3Zn3Al2 in the weld to increase the hardness of the weld through precipitation hardening mechanism.

參考文獻
1. 蔣啟明，「鋁材一般特性及銲接相關的性質」，銲接與切割雙月刊，12卷第1期，第38~41頁，民國九十一年一月。
2. 林昆民，銲條合金成份對AA7005鋁合金擠型材銲後熱處理製程之影響，國立台灣科技大學機械工程研究所碩士論文，民國九十四年。
3. 蔡和晉，錳元素含量對AA7003鋁合金銲件銲後熱處理至成影響之研究，國立台灣科技大學機械工程研究所碩士論文，民國九十七年。
4. D. R. Askeland and P. P. Phule, The Science and Engineering of Materials, 4th Edition, Thomson Learning, p. 594, 2003.
5. D.A. Porter, K.E. Easterling, Phase Transformation in Metals and alloy, 2nd, pp. 144-147, 1992.
6. P. N. T. Unwin, R. B. Nicholson, “The Nucleation and Initial Stages of Growth of Grain Boundary Precipitates in Al-Zn-Mg and Al-Mg alloys,” Acta Metallurgica, Vol. 17, pp. 1379-1393, 1969.
7. K. Hirano, R.P. Agarwala, M. Cohen, “Diffusion of Iron, Nickel and Cobalt in Aluminum,” Acta Metallurgica, Vol. 10, Issue 9, pp. 857-863, 1962.
8. D. Altenpohl, Aluminium and Aluminuim Legierungen, Springer Verlag, p. 773, 1965.
9. M.O. Speidel and M.V. Hyatt, Advances in corrosion science and technology,Plenum Press, NY, l(2), pp. 115-127, 1972.
10. 余坤城，渦電流檢測法訓練教材(初級)，中華民國非破壞檢測協會，pp. 12-13.
11. W. Wallace, J. C. Beddoes, M. C. deMalherbe, “A New Approach to the Problem of Stress Corrosion Cracking in 7075-T6 Aluminum, ” Aeronautics and Space Journal, vol.27, pp. 222~232, 1981.
12. J.K. Park and A.J. Ardell, “Microstructures of the Commercial 7075 Al Alloys in the T651 and T7 Tempers, ” Metallurgical and Materials Transactions A, vol. 14A, pp. 1957-1965, 1983.
13. Ohnishi and Shiota, “Heat Treatment To Reduce The Susceptibility Al-Zn-Mg-Cu Alloy to Stress Corrosion Cracking”, 輕金屬, Vol.36, no.10, pp. 647-656, 1986.
14. 王宜達，7005鋁擠型與5083鋁合金銲接件機械性質研究，國立台灣科技大學機械工程研究所碩士論文，民國八十九年。
15. 王振欽，銲接學，第10-1~10-2、10-5、10-13~10-14頁，高立圖書，民國九十一年。
16. W.H. Cubberly, ASM Handbook, ASM, Vol. 2, p. 194, 1986.
17. S. Kou, Welding Metallurgy, John Wiley & Sons, New York, pp. 129-295, 1987.
18. ASM, Welding Handbook: Welding, Brazing, and Soldering, ASM, Vol. 6, pp. 528-540,722-739, 1993.
19. S. Kou, and Y. Le, “Grain Structure and Solidification Cracking in Oscillated Arc Welds of 5052 Aluminum Alloy”, Metallurgical and Materials Transactions A, Vol. 16A, pp. 1345-1352, 1985.
20. J.R. Davis, ASM Specialty Handbook: Aluminum and Aluminum Alloys, ASM, pp. 376-419, 1993.
21. 姜志華、蔡金峰， 銲接冶金概論，徐氏出版社，第68-71頁，民國七十六年。
22. W. Gruhl, “The Stress Corrosion Behavior of High Strength Al-Zn-Mg Alloys,” Aluminium, Vol. 54, pp. 323-325, 1978.
23. W. Gruhl, “The Stress-Corrosion Behavior of High-Strength Al-Zn-Mg Alloys,” International Congress on Aluminum Alloys in the Aircraft Industry, pp. 171-174, 1976.
24. T.H. Sanders, Jr., E.A. Starke, Jr., “ Relationship of Microstructure to Monotonic and Cyclic Straining of Two Age Hardening Aluminum Alloys,” Metallurgical and Materials Transactions A, Vol. 7A, pp. 1407-1418, 1976.
25. A.K. Vasudevan, R.D. Doherty, Aluminum Alloys Contemporary Research and Applications, Academic Press, Inc., San Diego, pp. 35-170, 1989.
26. D.A. Hardwick, A.W. Thompson, I. M. Bernstein, “The Effect of Copper Content and Microsturcture on the Hydrogen Embrittlement of Al-6Zn-2Mg Alloys,” Metallurgical and Materials Transactions A, Vol. 14A, pp. 2517-2526, 1983.
27. B. Sarkar, M. Marek and E.A. Starke, Jr., “The Effect of Copper Content and Heat Treatment on the Stress Corrosion Characteristics of Al-6Zn-2Mg-XCu Alloys,” Metallurgical and Materials Transactions A, Vol. 12A, pp. 1939-1943, 1981.
28. Z. Lin, H. Ru, G. Zhao and G. Sun: 10th International Congress on Metallic Corrosion, Vol. 3, pp. 2369-2378, 1988.
29. F.M. Mazzolani, Aluminum and Aluminum Structure, 2nd Ed., pp. 7-8, 1987
30. E. A. Marquis and D. N. Seidman, “Nanoscale Structural Evolution of Al3Sc Precipitates in Al(Sc) Alloys,” Acta Materialia, Vol. 49, pp. 1909-1919, 2001.
31. S. Iwamura and Y. Miura, “Loss in Coherency and Coarsening Behavior of Al3Sc Precipitates,” Acta Materialia, Vol. 52, pp. 591-600, 2004.
32. J. Røyset and N. Ryum, “Some Comments on the Misfit and Coherency Loss of Al3Sc Particles in Al-Sc Alloys,” Scripta Materialia, Vol. 52, pp. 1275-1279, 2005.
33. H. Tsubakino, A. Yamamoto and T. Ohnishi, “Effect of Fe and Si on Precipitation of 7050 Aluminum Alloys,” International Conference on Thermo-mechanical Processing of Steels and Other Materials, pp. 1059-1064, 1997.
34. I.J. Polmear, “The Properties of Commercial Al-Zn-Mg Alloys: Practical Implications of Trace Additions of Silver,” Journal Institute of Metals , Vol. 89, pp. 193-202, 1961.
35. M. Nicolas, J.C. Werenskiold, A. Deschamps, F. Bley, F. Livet and J.P. Simon, “Study of Precipitate Microstructure in the Heat-Affected Zones of a Welded Al-Zn-Mg Alloy,” Italy, Proceedings of Euromat, Riminy, 2001.
36. G.E. Metzger, “Some Mechanical Properties of Welds in 6061 Aluminum Alloy Sheet,” Welding Journal, Vol. 56, No. 10, pp. 457-469, 1967.
37. T. Ma and G.D. Ouden, “Softening Behaviour of Al-Zn-Mg Alloys due to Welding,” Materials Science and Engineering A, Vol. 266, No.1, pp. 198-204, 1999.
38. R.J. Brungraber and F.G. Nelson, “Effect of Welding Variables on Aluminum Alloy Weldments,” Welding Journal, Vol.52, No.3, p. 97, 1973.
39. A.O. Kluken and B. Bjorneklett, “A Study of Mechanical Properties for Aluminum GMA Weldments,” Welding Journal, pp. 39-44, 1997.
40. A.Y. Ishchenko and V.O. Chapor, “Weldability of High-Strength Alloys of Al-Zn-Mg-(Cu) System,” The Paton Welding Journal, No. 4, pp. 5-10, 2000.
41. W.R. Oates, Welding Handbook, American Welding Society, Vol. 3, pp. 26 and 30-41, 1987.
42. M.O. Speidel, “Stress Corrosion Cracking of Aluminum Alloys,” Metallurgical and Materials Transactions A, Vol. 6A, pp. 631-642, 1975.
43. M. Talianker, B. Cina, “Retrogression and Reaging and the Role of Dislocations in the Stress Corrosion of 7000-Type Aluminum Alloys,” Metallurgical and Materials Transactions A, Vol. 20A, pp. 2087-2092, 1989.
44. 徐煌仁，AA7005鋁合金擠型材熱處理製程之研究，國立台灣科技大學機械工程研究所碩士論文，民國九十一年。
45. 柯漢光，7075鋁合金厚板材料RRA熱處理之研究，淡江大學機械工程研究所碩士論文，民國七十五年.
46. J. Robinson and P. Flynn, “Effects of Thermal Treatments on the Stress Corrosion Cracking Resistance of Forgings of the Aluminum Alloy 7010,” Key Engineering Materials, Vol. 99-100, pp. 143-150, 1995.
47. N.C. Danh, K. Rajan, and W. Wallace, “A TEM Study of Microstructural Changes during Retrogression and Reageing in 7075 Aluminum,” Metallurgical and Materials Transactions A, Vol. 14A, pp. 1843-1850, 1983.
48. M.U. Islam and W. Wallace, “Retrogression and Reaging Response of 7475 Aluminum Alloy,” Metals Technology, Vol. 10, pp. 386-392, 1983.
49. K. Rajan, W. Wallace, J.C. Beddoes,“ Microstructural Study of a High-Strength Stress-Corrosion Resistant 7075 Aluminum Alloy,” Jourmal of Materials Science, Vol. 17, p. 2817, 1982.
50. The Aluminum Association, Inc, International Alloy Designations and Chemical Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys, 2009
51. American Welding Society Committee, Structural Welding Code-Aluminum, American Welding Society, pp. 115-128, 1997.
52. ASTM Standards B597, “Standard Practice for Heat Treatment of Aluminum Alloys,” 1992.
53. ASM, Metals Handbook: Metallurgy and Microstructure, 9th Ed., Vol. 9, pp. 351-360, 1985.
54. ASTM Standards B557-94, Standard Test Methods of Tension Testing Wrought and Cast Aluminum and Magnesium Alloy Products, pp. 411-423, 1994.
55. 黃清添，析出製程參數對AA7005鋁擠型合金機械性質與抗應力腐蝕之影響，國立台灣科技大學機研所碩士論文，民國九十二年。
56. 莊東漢，材料破損分析，五南出版社，第135頁，民國九十六年。
57. R.A. Woods, “Metal Transfer in Aluminum Alloys,” Welding Journal, Vol. 59, pp. 59-66, 1980.
58. L.F Mondolfo, Aluminum Alloys:Structure and Properties Part 3, Butter Worths, pp. 577-590, 1976.