臺灣博碩士論文加值系統

本論文主旨在研究Ti-6Al-4V合金之TIG銲接特性，探討不同的熱處理對銲件機械性質與微觀結構之影響。銲件熔融區出現晶粒長大之現象，在TEM觀察下，組織呈多向分佈，為a+b雙相奈米結構；銲後退火處理﹙ANN/704℃/2hr/A.C.﹚之熔融區，經HRTEM觀察發現a2-Ti3Al介金屬化合物產生，此介金屬化合物對強度有相當的強化效應，其延伸率伴隨著有下降的趨勢；經銲後固溶﹙S.T./954℃/15min/WQ﹚及時效處理﹙A.A./704℃/4hr/FC﹚之熔融區，HRTEM觀察發現，有大量約2~5nm r-TiAl介金屬化合物產生，拉伸實驗顯示，該相提升銲件降伏強度至838 MPa，而延伸率劇降為2.8%。

This study is focused on the influences of various post-weld heat treatments ﹙PWHT﹚on the microstructures and the mechanical properties of the TIG-welded Ti-6Al-4V weldment. Metallographic observation shows that the fusion zone of the weldment with no PWHT was a relatively larger grain-size microstructure. The enhanced grain-size microstructure of fusion zone was identified by TEM to be a nanostructure of a+b duplex phase whose orientation was random. For the weld with a PWHT of annealing at 704°C for 2 hours and air cooling, the a2-Ti3Al metallic compound was found to precipitate in the fusion zone. This type of metallic compound contributed a significant strengthening effect together with its decreased elongation. For the weld with a PWHT of solutioning at 954°C for 15 minutes, water-quenching, and following ageing at 704°C for 4 hours and furnace cooling, a great amount of r-TiAl compounds in size of 2~5 nm was found on the fusion zone. The tensile test, shows that the precipitation of r-TiAl metallic compounds of the 704°Cx4 hrs-aged weld increased the yield strength from 802 to 838 MPa and decreased the elongation from 11.6 to 2.8%.

致謝 ii
摘要 iii
ABSTRACT iv
目錄 v
表目錄 viii
圖目錄 ix
符號說明 xii
1. 前言 1
2. 文獻回顧 2
2.1 鈦與鈦合金介紹 2
2.2 添加合金元素對鈦的影響 2
2.2.1 a穩定元素 2
2.2.2 b穩定元素 3
2.3 鈦合金的分類 3
2.3.1 a型鈦合金 3
2.3.2 Near a型鈦合金 4
2.3.3 a+b型鈦合金 4
2.3.4 b型鈦合金 5
2.3.5 Near b型鈦合金 5
2.4 Ti-6Al-4V合金 5
2.5 鈦合金熱處理機制 6
2.5.1 弛力退火或稱應力消除 6
2.5.2 退火處理 7
2.5.3 固溶處理 8
2.5.4 固溶處理加時效 9
2.6 Ti-6Al-4V合金之顯微組織 10
2.6.1 等軸結構 10
2.6.2 層狀結構 11
2.6.3 麻田散體結構 11
2.6.4 介金屬化合物 12
2.7 惰性氣體電弧銲 13
2.7.1 TIG銲接原理與機構 13
2.7.2 TIG銲接之優劣 14
2.8 鈦合金的銲接性 14
2.8.1 銲件微觀組織 15
2.8.2 銲件機械性質 15
3. 實驗方法 33
3.1 實驗材料 33
3.2 實驗規劃 33
3.3 金相試驗 33
3.4 微硬度測試 34
3.5 掃描式電子顯微鏡觀察 34
3.6 Ｘ光繞射儀 34
3.7 穿透式電子顯微鏡觀察 35
4. 結果與討論 43
4.1 機械性質試驗 43
4.1.1 硬度測試 43
4.1.2 拉伸測試 43
4.2 OM及SEM顯微組織觀察 45
4.2.1 A.R.顯微組織 45
4.2.2 HAZ顯微組織 46
4.2.3 FZ顯微組織 46
4.3 結晶結構與微結構分析 47
4.3.1 X-Ray繞射分析 47
4.3.2 TEM觀察 47
4.3.2.1 A.W.之FZ區域 47
4.3.2.2 P.W.+ANN之FZ區域 48
4.3.2.3 P.W.+S.T.+.A.A之FZ區域 49
5. 結論 76
參考文獻 77
自傳 82

[1]李志聖，“Ti-6Al-4V合金銲接特性之研究”，碩士論文，國防大學中正理工學院兵器工程研究所，桃園，第18-36頁，2005。
[2]賴耿陽，金屬鈦理論與應用，復漢（翰）出版社，台南，第31-37頁，1990。
[3]陳家暘，“脈衝電流對Ti-6Al-4V鈦合金銲道結構及機械性質影響性之研究”，碩士論文，大葉大學車輛工程學系研究所，彰化，第8-21頁，2003。
[4]劉偉隆、林淳杰、曾春風、陳文照，物理冶金，全華科技，台北，第20-20、26、30頁，2002。
[5]Flower, H. M., “Microstructural Development in Relation to Hot Working of Titanium Alloys,”Materials Science and Technology, Vol. 6, pp. 1082-1092, 1990.
[6]王金友、葛志明、周彥邦，航空用鈦合金，上海科學技術出版社，上海，第133-179頁，1985。
[7]蔡智仁，“Ti-15V-3Cr-3Sn-3Al合金銲接特性之研究”，碩士論文，國防大學中正理工學院兵器工程研究所，桃園，第7-35頁，2005。
[8]李成功、傅恒志、于翹，航空航天材料，國防工業出版社，北京，第42-46頁，2002。
[9]何光遠，機械工程手冊3－金屬材料，五南圖書出版社，台北，第6-43、44、49、50頁，2002。
[10]梁元彰，“熱機處理對Ti-6Al-4V相變態的影響”，碩士論文，國立台灣大學材料科學與工程學研究所，台北，第20頁，1999。
[11]林宗翰，“Ti-6Al-4V合金熱軋變形行為及顯微組織研究”，碩士論文，國立中正大學機械系研究所，嘉義，第12頁，1998。
[12]Metals Handbook 9th Edition, ASM internation, USA, Vol. 4, pp. 765-767, 1990.
[13]Fan, Z., “The β ω Transformation During Room Temperature Aging in Rapidly Solidified Ti-6Al-4V Alloy,” Scripta Metallurgica et Materialia, Vol. 31, pp. 1519-1524, 1994.
[14]Baeslack, W. A., and Banas, C. M.,“A Comparative Evaluation of Laser and Gas Tungsten Arc Weldments in High-Temperature Titanium Alloys,”Welding Research Supplement, pp. 121s-130s, 1981.
[15]王忠益，“鈦合金鑄件後製程之化學銑製及表面性質研究”，碩士論文，國立台北科技大學材料及資源工程系研究所，台北，第7頁，1999。
[16]Sha, W., and Guo, Z.,“Phase Evoluyion of Ti-6Al-4V During Continuous Heating,”Journal of Alloys and Compounds, Vol. 290, pp. L3-L7, 1999.
[17]Malinov, S., Markovsky, P., Sha, W., and Guo, Z., “Reistivity Study and Computer Modelling of the Isothermal Transformation Kinetics of Ti-6Al-4V and Ti-6Al-2Sn-4Zr-2Mo-0.08Si Alloys,” Journal of Alloys and Compounds, Vol. 314, pp. 181-192, 2001.
[18]Ding, R., Guo, Z. X., and Wilson, A., “Microstructural Evolution of a Ti-6Al-4V Alloy During Thermomechanical Processing,” Materials Science and Engineering A, Vol. A327, pp. 233-245, 2001.
[19]Manero, J. M., Gil, F. J., and Planell, J. A., “Deformation Mechananisms of Ti-6Al-4V Alloy with a Martensitic Microstructure Subjected to Oligocyclic Fatigue,” Acta Materialia, Vol. 48, pp. 3353-3359, 2000.
[20]黃佳貴，“Ti-6Al-4V合金對Ag-Cu基活性填料硬銲接合性之研究”，碩士論文，中華大學機械與航空太空工程研究所，新竹，第71頁，1999。
[21]Filip, R., Kubiak, K., Ziaja, W., and Sieniawaki, J., “The Effect of Microstructure on the Mechanical Properties of Two-Phase Titanium Alloys,” Materials Processing Technology, Vol. 133, pp. 84-89, 2003.
[22]Ahmed, T., and Rack, H. J., “Phase Transformations During Cooling in a+b Titanium Alloys,” Materials Science and Engineering A, Vol. A243, pp. 206-211, 1998.
[23]Ding, R., and Guo, Z. X., “Microstructural Evolution of a Ti-6Al-4V Alloy During b-phase Processing: Experimental and Simulative Investigations,” Materials Science and Engineering A, Vol. A365, pp. 172-179, 2004.
[24]陳學人，“Ti-6Al-4V合金之相變態特性與組織分析”，碩士論文，國立台灣大學材料科學與工程學研究所，台北，第14-16頁， 2001。
[25]陳明謙，“Ti-6Al-4V各種不同組織的拉伸破壞行為觀察”，碩士論文，國立台灣大學材料科學與工程學研究所，台北，第8-10頁，1999。
[26]Mishin, Y., and Herzig, C., “Overview NO. 136 Diffusion in the Ti-Al System,” Acta Materialia, Vol. 48, pp. 589-623, 2000.
[27]Djanarthany, S., Viala, J. C., and Bouix, J., “An Overview of Monolithic Titanium Aluminides based on Ti3Al and TiAl,” Materials Chemistry and Physics, Vol. 72, pp. 301-319, 2001.
[28]Welsch, G., Lutjering, G., Gazioglu, K., and Bunk, W., “Deformation Characteristics of Age Hardened Ti-6Al-4V,” Metallurgical Transactions A, Vol. 8A, pp. 169-177, 1977.
[29]周長彬、蔡丕樁、郭央甚，銲接學，全華科技圖書股份有限公司，台北，第48-92頁，1991。
[30]Greenfield, M. A., and Duvall, D. S., “Welding of an Advanced High Strength Titanium Alloy,” Welding Reserch Supplement, pp. 73s-80s, 1975.
[31]Wang, S. H., Wei, M. D., and Tasy, L. W., “Tensile Properties of LBW Welds in Ti-6Al-4V Alloy at Evaluated Temperatures Belows 450℃,” Materials Letters, Vol. 57, pp. 1815-1823, 2003.
[32]Zhou, W., and Chew, K. G., “Effect of Welding on Impact Toughness of Butt-Joint in a Titanium Alloy,” Materials Science and Engineering A, Vol. A347, pp. 180-185, 2003.
[33]Thomas, G., Ramachandra, V., Nair, M. J., Nagarajan, K. V., and Vasudevan, R., “Effect of Preweld and Postweld Heat Treatment on the Properties of GTA Welds in Ti-6Al-4V Sheet,” Welding Research Supplement, pp. 15s-20s, 1992.
[34]Borggreen, K., and Wilson, I., “Use of Postweld Heat Treatment to Improve Ductility in Thin Sheets of Ti-6Al-4V,” Welding Research Supplement, pp. 1s-9s, 1980.
[35]Mazumder, J., and Steen, W. M., “Microstructure and Mechanical Properties of Laser Welded Titanium 6Al-4V,” Metallurgical Transactions A, Vol. 13A, pp. 865-871, 1982.
[36]Oh, J., Kim, N. J., Lee, S., and Lee, E. W., “Correlation of Fatigue Properties and Microstructure in Vestment Cast Ti-6Al-4V Welds,” Materials Science and Engineering A, Vol. A340, pp. 232-242, 2003.
[37]Hunter, G. B., Hodi, F. S., and Eager, T. W., “High Cycle Fatigue of Weld Repaired Cast Ti-6Al-4V,” Metallurgical Transactions A, Vol. 13A, pp. 1589-1594, 1982.
[38]Mahajan, Y., and Baeslack, W. A., “Transgranular Fracture of Heat-Treated Weldments in a High-Strength Alpha-Beta Titanium Alloy,” Scripta Metallurgica, Vol. 13, pp. 1125-1129, 1979.
[39]Hallum, D. L., and Baeslack, W. A., “Nature of Grain Refinement in Titanium Alloy Welds by Microcooler Inoculation,” Welding Reserch Supplement, pp. 326s-336s, 1990.
[40]Yunlian, Q., Ju, D., Quan, H., and Liying, Z., “Electron Beam Welding, Laser Beam Welding and Gas Tungsten Arc Welding of Titanium Sheet,” Materials Science and Engineering A, Vol. A280, pp. 171-181, 2000.
[41]Denney, P. E. and Metzbower, E. A., “Laser Beam Welding of Titanium,” Welding Research Supplement, pp. 343s-347s, 1989.
[42]Murthy, K. K., and Sundaresan, S., “Fracture Toughness of Ti-6Al-4V After Welding and Postweld Heat Treatment,” Welding Research Supplement, pp. 81s-91s, 1997.
[43]Mishra, S., and Debroy, T., “Measurements and Monte Carlo Simulation of Grain Growth in the Heat-Affected Zone of Ti-6Al-4V Welds,” Acta Materialia, Vol. 52, pp. 1183-1192, 2004.
[44]吳會強、馮吉才、何景山、張秉剛，“Ti-6Al-4V電子束焊接焊縫區域精細組織特徵”，航空材料學報，第25卷，第三期，第21-24頁，2005。
[45]Semiatin, S. L., Fagin, P. N., Glavicic, M. G., Sukonnik, I. M., and Ivasishin, O. M., “Influence on Texture on Beta Grain-Growth During Continuous Annealing of Ti-6Al-4V,” Materials Science and Engineering A, Vol. A299, pp. 225-234, 2001.
[46]Gil, F. J., Manero, J. M., Ginebra, M. P., and Planell, J. A., “The Effect of Cooling Rate on the Cyclic Deformation of b-Annealed Ti-6Al-4V,” Materials Science and Engineering A, Vol. A349, pp. 150-155, 2003.