| 研究生: |
吳佳霖 Wu, Jia-Lin |
|---|---|
| 論文名稱: |
雷射與電弧銲接製程對鎳基690合金銲接特性與應力腐蝕破裂行為之研究 Welding characteristics and stress corrosion cracking behavior of nickel-based alloys 690 by laser beam and arc welding processes |
| 指導教授: |
李驊登
Lee, Hwa-Teng |
| 學位類別: |
博士 Doctor |
| 系所名稱: |
工學院 - 機械工程學系 Department of Mechanical Engineering |
| 論文出版年: | 2010 |
| 畢業學年度: | 98 |
| 語文別: | 英文 |
| 論文頁數: | 154 |
| 中文關鍵詞: | 鎳基690合金 、銲接 、熱循環曲線 、溫度分佈 、殘留應力 、敏化程度 、晶界特性分佈 、沿晶腐蝕 、應力腐蝕 |
| 外文關鍵詞: | Alloy 690, Welding, Thermal cycle, Temperature distribution, Residual stress, Degree of sensitization, Grain boundary character distribution, Intergranular corrosion, Stress corrosion cracking. |
| 相關次數: | 點閱:92 下載:1 |
| 分享至: |
| 查詢本校圖書館目錄 查詢臺灣博碩士論文知識加值系統 勘誤回報 |
本研究採用Nd:YAG雷射,在三種不同雷射輸出功率(1250、1500和1750W)下,搭配矩形脈衝波(PW)及連續波(CW),對鎳基690合金進行走銲實驗(BOP),探討上述不同雷射參數對690合金之銲縫剖面,熔融率(MR),微結構和微硬度之影響,以期獲得對接銲臨界貫穿走速。接著,利用最佳臨界貫穿走速條件對690合金進行雷射銲接(LBW)與鎢極氣體電弧銲接(GTAW)之對接銲實驗,於銲接過程中精確地量測銲件各點所經歷的銲接熱循環曲線(即峰值溫度、加熱速率和冷卻速率)和溫度分佈(即溫度梯度)。本研究目的為探討銲接熱循環曲線和溫度分佈結果,與其殘留應力分佈、晶界特性分佈(GBCD)、敏化程度(DOS)及碳化物種類之相關性,以建立LBW與GTAW兩銲接製程之峰值溫度、加熱速率、冷卻速率及溫度分佈對690合金銲件之抗沿晶腐蝕(IGC)和抗應力腐蝕開裂(SCC)的影響。
BOP實驗結果顯示,當固定雷射平均輸出功率條件下,由於脈衝波試片具有較連續波試片為高的熔融比,使其臨界貫穿走速較高且銲道較為狹窄,所以,脈衝波試片之銲道可獲得較細的枝晶結構和較高的硬度值。而對接銲實驗結果表明,由於LBW製程功率密度高達104−105 W/mm2,可大幅降低入熱量(112 J/mm),並提供非常陡峭的溫度分佈、非常高的加熱速率(16080 ˚C/s 在銲道處)及非常高的冷卻速率,故相較於GTAW銲道,LBW銲道則具有較細緻的枝晶結構與較高的硬度值。另一方面,相較於GTAW銲件,其LBW銲件陡峭的溫度分佈可有效地降低縱向拉伸殘留應力區之範圍。藉由LBW和GTAW兩銲件之雙環動電位再活化法(DL-EPR)實驗曲線得知,LBW銲道與銲接衰化區的Ir/Ia值分別只為0.15%、0%;GTAW銲件的相應區域卻高達0.41%、0.6%,故其LBW銲件之敏化程度明顯遠較GTAW銲件為低許多。根據GBCD結果顯示,在LBW銲道處,其低能量Σ重位點陣(CSL)晶界(1≦Σ≦9)之比例明顯高於GTAW銲道。而由改良式惠式試驗結果表明,相較於GTAW銲件,其LBW銲道與銲接衰化區皆具有顯著抵抗沿晶腐蝕與枝晶間腐蝕(IDC)的能力。這是因為在LBW銲道與銲接衰化區處皆具有非常高的冷卻速率,導致通過Cr23C6碳化物析出溫度範圍620–1020˚C的時間不足,只為1.2–1.6秒,大幅抑制了碳化物析出和沿晶界缺鉻區出現之所致。最後,U-Bend固定變形與慢應變速率試驗(SSRT)結果皆表明,LBW製程技術可顯著地改善690合金銲件抗應力腐蝕的能力。
This study initially investigates the influences of three mean Nd:YAG laser output powers (1250, 1500, and 1750W) combined with rectangular pulse wave (PW) and continuous wave (CW) on weld bead profiles, melting ratios (MR), microstructures, and microhardnesses of alloy 690 for bead on plate (BOP) welding specimens, in order to achieve the critical welding speed for the just fully penetrating the butt weld. Moreover, precise measurements of the welding thermal cycles (i.e. the peak temperature, the heating rate and the cooling rate) and temperature distributions (i.e. temperature gradient) continuously at various points of the alloy 690 butt weldment during laser beam welding (LBW) and gas tungsten arc welding (GTAW) processes were taken. The resulting thermal cycle and temperature distribution profiles were then correlated with the distribution of residual stress, grain boundary character distribution (GBCD), degree of sensitization (DOS), and carbide type with an aim to study and establish the combined influences of peak temperature, heating rate, cooling rate, and temperature distribution on the intergranular corrosion (IGC) and stress corrosion cracking (SCC) resistance of alloy 690 weldments.
The results showed that PW specimens have significantly higher MR values than those of CW specimens under constant mean laser output power. The PW specimen is characterized by its full penetration capability at higher critical welding speed, which results in a narrower weld bead. As a result, a denser dendritic structure and higher microhardness can be obtained in the fusion zone (FZ). For the butt welding specimens, the LBW process, with a power density as high as 104−105 W/ mm2, has significantly lower heat input (112 J/mm) on the weldment than the GTAW process, which provides a very steep temperature distribution, a very great heating rate (16080˚C/s in the FZ), and a very high cooling rate. As a result, the sub-grain structure in the FZ of the LBW weldment appears to be denser than that in the FZ of the GTAW weldment. Moreover, the very steep temperature distribution in the LBW weldment effectively reduced the size of the longitudinal tensile residual stress zone relative to that in the GTAW weldment. A comparison of the double-loop electrochemical potentiokinetic reactivation (DL-EPR) curves on the FZs and weld decay zones (WDZs) of the LBW and GTAW weldments revealed that the Ir/Ia values in the FZ and WDZ of the LBW specimen were about 0.15% and 0%, respectively, while those of the corresponding regions of the GTAW specimen were about 0.41% and 0.6%, respectively. Therefore, the DOS value of the LBW specimen was much lower than those of the GTAW specimens. Furthermore, the GBCDs by orientation image maps showed that the fraction of low energy Σ coincidence site lattice boundaries (1≦Σ≦9) in the FZ of the LBW weldment is significantly higher than that in the FZ of the GTAW weldment. In particular, the modified Huey test results revealed that in the LBW weldment, compared with the GTAW weldment, interdendritic corrosion (IDC) and IGC were significantly arrested in the FZ and the WDZ, respectively. This occurred because the very rapid cooling rates in the FZ and WDZ during welding leads to an insufficient exposure time of around 1.2–1.6s through the Cr23C6 carbide precipitation temperature range of 620−1020˚C, suppressing Cr-carbide precipitation and Cr-depletion along grain boundaries in the FZ and WDZ, respectively. Consequently, both the U-bend constant deformation and slow strain rate testing results showed that the LBW technique makes a significant improvement in the SCC resistance of alloy 690 weldments.
1. P.M. Scott, An overview of materials degradation by stress corrosion in PWRs, in: D. Féron, J.M. Olive (Eds.), Corrosion Issues in Light Water Reactors: Stress Corrosion Cracking, Woodhead, England, 2007, pp. 3–24.
2. C.P. King, et al., Materials reliability program PWSCC of alloy 600 type materials in non-steam generator tubing applications - survey report through June 2002: part 1: PWSCC in components other than CRDM/CEDM penetrations (MRP-87), Technical report 1007832, EPRI, Palo Alto, CA, June, 2003.
3. K. Ahluwalia, C. King, Materials reliability program: review of stress corrosion cracking of alloys 182 and 82 in PWR primary water service (MRP-220), Technical report 1007832, EPRI, Palo Alto, CA, October, 2007.
4. W. Bamford, J. Hall, Cracking of alloy 600 nozzle and welds in PWRs: Review of cracking events and repair service experience, in: T. R. Allen, P. J. King and L. Nelson (Eds.), Proceedings of the 12th International Conference on Environmental Degradation of Materials in Nuclear Power System-Water Reactors-TMS, The Minerals, Metals & Materials Society, Salt Lake City, USA, 2005, pp. 959–965.
5. K. Okimura et al., Maintenance technologies for SCC which support stable operations of pressurized water reactor power plants, Mitsubishi Heavy Industries, Ltd. Technical Review, Vol. 43, No. 4, 2006.
6. Japan Nuclear Energy Safety Organization (JNES), Aging management of nuclear power plant, December, 2007.
7. G. Frederick, A. Mcllree, Materials reliability program: selection of materials and fabrication of weldments for investigation of PWSCC susceptibility in the alloy 600 and 690 weld heat affected zones (MRP-161), Technical report 1011805, EPRI, Palo Alto, CA, March, 2006.
8. J. Hickling, A. Ahluwalia, et al., Advanced testing techniques to measure the PWSCC resistance of alloy 690 and its weld metals, Technical report 1011202, EPRI, Palo Alto, CA, and U.S. Department of Energy, Washington, October, 2004.
9. D.L. Harrod, R.E. Gold, and R.J. Jacko, Alloy optimization for PWR steam generator heat-transfer tubing, JOM 53 (2001) 14–17.
10. V. Čihal, Intergranular Corrosion of Steels and Alloys, Elsevier, Amsterdam, 1984.
11. G.S. Was, H.H. Tischner, and R.M. Latanision, The influence of thermal treatment on the chemistry and structure of grain boundaries in inconel 600, Metall. Mater. Trans. A 12A (1981) 1397–1408.
12. R.A. Page, A. Mcminn, Relative stress corrosion susceptibilities of alloys 690 and 600 in simulated boiling water reactor environments, Metall. Mater. Trans. A 17A (1986) 877–887.
13. J.J. Kai, C.H. Tsai, T.A. Huang, and M.N. Liu, The effects of heat treatment on the sensitization and SCC behavior of INCONEL 600 alloy, Metall. Mater. Trans. A 20A (1989) 1077–1088.
14. J.J. Kai, G.P. Yu, C.H. Tsai, M.N. Liu, and S.C. Yao, The effects of heat treatment on the chromium depletion, precipitate evolution, and corrosion resistance of INCONEL alloy 690, Metall. Mater. Trans. A 20A (1989) 2057–2067.
15. M.K. Ahn, H.S. Kwon, and J.H. Lee, Predicting susceptibility of alloy 600 to intergranular stress corrosion cracking using a modified electrochemical potentiokinetic reactivation test, Corrosion 51 (1995) 441–449.
16. M. Casales, V.M. Salinas-Bravo, A. Martinez-Villafañe, J.G. Gonzalez-Rodriguez, Effect of heat treatment on the stress corrosion cracking of alloy 690, Mater. Sci. Eng., A 332 (2002) 223–230.
17. H. Sahlaoui, H. Sidhom, J. Philibert, Prediction of chromium depleted-zone evolution during aging of Ni-Cr-Fe alloys, Acta Mater. 50 (2002) 1383–1392.
18. Y.Y. Chen, L.B. Chou, L.H. Wang, J.C. Oung, and H.C. Shih, Electrochemical polarization and stress corrosion cracking of alloy 690 in 5-M chloride solutions at 25°C, Corrosion, 61 (2005) 1–9.
19. W.T. Tsai, C.L. Yu, J.I. Lee, Effect of heat treatment on the sensitization of Alloy 182 weld, Scr. Mater. 53 (2005) 505–509.
20. Y.F. Yin, R.G. Faulkner, Model predictions of grain boundary chromium depletion in Inconel 690, Corros. Sci. 49 (2007) 2177–2197.
21. D. Radaj, Heat effects of welding: temperature field, residual stress, distortion, Springer-Verlag, New York, 1992.
22. C.M. Adams Jr., Heat Flow in Welding, in: C. Weisman (Ed), Fundamentals of Welding, vol. 1, Welding Handbook , seventh ed., American Welding Society, 1976, pp. 90–97.
23. S. Kou, Welding Metallurgy, Wiley, New York, 1987.
24. J.C. Danko, Stress-Corrosion Cracking of Weldments in Boiling Water Reactor Service, in: R. H. Jones (Ed.), Stress-Corrosion Cracking, ASM International, Ohio, 1992, pp. 345–354.
25. H.D. Solomon, Influence of prior deformation and composition on continuous cooling sensitization of AISI 304 stainless steel, Corrosion 41 (1985) 512–517.
26. J.W. Simmons, D.G. Atteridge, and S.M. Bruemmer, Continuous cooling sensitization of type 316 austenitic stainless steel, Corrosion 48 (1992) 976–982.
27. T. Nagashima, A. Yokoyama, T. Akaba, Y. Nagura, O. Matsumoto and T. Ishide, Development of YAG laser welding robot system for repairing heat exchanger tubes, Weld. world. 34 (1994) 133–138.
28. J.D. Kim, C.J. Kim, C.M. Chung, Repair welding of etched tubular component of nuclear power plant by Nd:YAG laser J. Mater. Process. Technol. 114 (2001) 51–56.
29. T.Y. Kuo and S.L. Jeng, Porosity reduction in Nd–YAG laser welding of stainless steel and inconel alloy by using a pulsed wave, J. Phys. D: Appl. Phys. 38 (2005) 722–728.
30. W.M. Steen, Laser Material Processing, Springer-Verlag, New York, 1991.
31. T.Y. Kuo and Y.D. Lin, Mater. Trans., JIM 48 (2007) 219–226.
32. J.D. Kim, J.H. Moon, C-ring stress corrosion test for Inconel 600 and Inconel 690 sleeve joint welded by Nd:YAG laser, Corros. Sci. 46 (2004) 807–818.
33. A. Yokoyama, T. Nagashima, O. Matsumto, Y. Nagura, T. Ishide, in: The 5th International Symposium of the Japan Welding Society, Tokyo, 1990, pp. 29–34.
34. G. Bao, S. Iguro, M. Inkyo, K. Shinozaki, Y. Mahara, H. Watanabe, Repair of stress corrosion cracking in overlaying of Inconel 182 by laser surface melting, Weld. world. 49 (2005) 37–44.
35. G. Bao, K. Shinozaki, S. Iguro, M. Inkyo, M. Yamamoto, Y. Mahara, H. Watanabe, Stress corrosion cracking sealing in overlaying of Inconel 182 by laser surface melting, J. Mater. Process. Technol. 173 (2006) 330–336.
36. H. Kokawa, M. Shimada, Y.S. Sato, Grain-boundary structure and precipitation in sensitized austenitic stainless steel, JOM 52 (2000) 34–37.
37. H.Y. Bi, H. Kokawa, Z.J. Wang, M. Shimada, Y.S. Sato, Suppression of chromium depletion by grain boundary structural change during twin-induced grain boundary engineering of 304 stainless steel, Scripta Mater. 49 (2003) 219–223.
38. P. Lin, G. Palumbo, U. Erb, K.T. Aust, Influence of grain boundary character distribution on sensitization and intergranular corrosion of alloy 600, Scripta Metall. Mater. 33 (1995) 1387–1392.
39. E.M. Lehockey, G. Palumbo, P. Lin, A.M. Brennenstuhl, On the relationship between grain boundary character distribution and intergranular corrosion, Scripta Mater. 36 (1997) 1211–1218.
40. Y.S. Lim, J.S. Kim, H.P. Kim, H.D. Cho, J. Nucl. Mater. 335 (2004) 108–114.
41. H. Kokawa, M. Shimada, M. Michiuchi, Z.J. Wang, Y.S. Sato, Acta Mater. 55 (2007) 5401–5407.
42. S. Yang, Z. Wang, H. Kokawa, Y.S. Sato, Mater. Sci. Eng. A 474 (2008) 112–119.43.
43. C. Dawes, Laser Welding, Woodhead, Cambridge, England, 1992.
44. J.F. Ready, D.F. Farson (Eds.), LIA Handbook of Laser Materials Processing, Laser Institute of America, Orlando, FL, 2001.
45. I. Hrivňák, Theory of Weldability of Metals and Alloys, Elsevier, Amsterdam, 1992.
46. J. Mathar, Trans. ASME 4 (1934) 249–254.
47. ASTM E837-01, Standard test method for determining residual stresses by the hole drilling strain-gage method, ASTM, Philadelphia, PA, 2001.
48. S. Xia, B.X. Zhou, W.J. Chen, W.G. Wang, Scripta Mater. 54 (2006) 2019–2022.
49. J. Hou, J.Q. Wang, W. Ke, E.H. Han, Mater. Sci. Eng. A 518 (2009) 19–26.
50. ASTM G5-94, Standard reference test method for making potentiostatic and potentiodynamic anodic polarization measurements, ASTM, Philadelphia, PA, 2004.
51. ASTM A262-02a, Standard practices for detecting susceptibility to intergranular attack in austenitic stainless steels, ASTM, Philadelphia, PA, 2002.
52. ASTM G30-97, Standard practice for making and using U-bend stress-corrosion test specimens, ASTM, Philadelphia, PA, 2003.
53. ASTM G129-00, Standard practice for slow strain rate testing to evaluate the susceptibility of metallic materials to environmentally assisted cracking, ASTM, Philadelphia, PA, 2006.
54. D.L. Olson et al., ASM Handbook, Vol. 6: Welding, Brazing, and Soldering, ASM International, Materials Park, OH, 1993.
55. O. Perret, P. Naudy and M. Bizouard: ‘Keyhole formation study in pulse Nd:YAG laser welding’, Proc. 18th Int. Conf. on ‘International congress on applications of lasers & electro-optics (ICALEO'99)’, San Diego, CA, USA, Nov. 1999, Paper D177–D186.
56. D.T. Swift-Hook and A.E.F. Gick, Penetration welding with lasers, Weld. J. 52 (1973) 492–499.
57. A. Punkari, D.C. Weckman and H.W. Kerr, Effect of magnesium content on dual beam Nd:YAG laser welding of Al-Mg alloys, Sci. Technol. Weld. Join. 8 (2003) 269–281.
58. G. Zhao, C. Cho and J.D. Kim, Application of 3-D finite element method using lagrangian formulation to dilution control in laser cladding process, Int. J. Mech. Sci. 45 (2003) 777–796.
59. Special Metals Corporation: ‘INCONEL alloy 600’, Publication Number SMC-027, 2002.
60. K. Poorhaydari, B.M. Patchett and D.G. Ivey, Estimation of cooling rate in the welding of plates with intermediate thickness, Welding J. 84 (2005) 149–155.
61. P.W. Fuerschbach and G.A. Knorovsky, A study of melting efficiency in plasma arc and gas tungsten arc welding, Welding J. 70 (1991) 287–297.
62. J.F. Key, Arc Physics of Gas-Tungsten Arc Welding, in: ASM Handbook, Welding, Brazing, and Soldering, vol. 6, ASM International, Ohio, 1993, pp. 30–35.
63. P.W. Fuerschbach, D.O. MacCallum, Variation of laser energy transfer efficiency with weld pool depth, in: Proceedings of the 14th International Congress on the Applications of Lasers and Electro-Optics (ICALEO ‘95), California, November, 1995, pp. 493–497.
64. P.W. Fuerschbach, Measurement and prediction of energy transfer efficiency in laser beam welding, Welding J. 75 (1996) 24–34.
65. K.E. Easterling, Introduction to the Physical Metallurgy of Welding, Butterworth-Heinemann Ltd., Oxford, 1992.
66. H.T. Lee, S.L. Jeng, C.H. Yen and T.Y. Kuo, Dissimilar welding of nickel-based Alloy 690 to SUS 304L with Ti addition, J. Nucl. Mater. 335 (2004) 59–69.
67. K. Masubuchi, Analysis of Welded Structures, Pergamon Press, Oxford, 1980.
68. G.S. Schajer et al., Hole-drilling and ring core methods, in: J. Lu (Ed.), Handbook of Measurement Residual Stresses, Fairmont Press, Lilburn, GA, 1996, pp 5–34.
69. Y.C. Lin and C.P. Chou, J. Mater. Process. Technol. 48 (1995) 693–698.
70. T.Y. Kuo, H.T. Lee, Effects of filler metal composition on joining properties of alloy 690 weldments, Mater. Sci. Eng., A 388 (2002) 202–212.
71. S.L. Jeng, H.T. Lee, T. E. Weirich, W.P. Rebach, Microstructual study of the dissimilar joints of Alloy 690 and SUS 304L stainless steel, Mater. Trans., JIM 48 (2007) 1–9.
72. H.T. Lee, J.L. Wu, The effects of peak temperature and cooling rate on the susceptibility to intergranular corrosion of alloy 690 by laser beam and gas tungsten arc welding, Corros. Sci. 51 (2009) 439–445.
73. B.T. Lu, Z.K. Chen, J.L. Luo, B.M. Patchett, Z.H. Xu, Pitting and stress corrosion cracking behavior in welded austenitic stainless steel, Electrochim. Acta 50 (2005) 1391–1403.
74. W.E. Mayo, Predicting IGSCC/IGA susceptibility of Ni–Cr–Fe alloys by modeling of grain boundary chromium depletion, Mater. Sci. Eng., A 232 (1997) 129–139.
75. H. Sahlaoui, H. Sidhom, J. Philibert, Predition of chromium depleted-zone evolution during aging of Ni-Cr-Fe alloys, Acta Mater. 50 (2002) 1383–1392.
76. H.D. Solomon, Influence of prior deformation on continuous cooling sensitization of type 304 stainless steel, Corrosion 36 (1980) 356–361.
77. H. D. Solomon, D. C. Lord, Influence of strain during cooling on the sensitization of type 304 stainless steel, Corrosion 36 (1980) 395–399.
78. H.T. Lee, J.L. Wu, Correlation between corrosion resistance properties and thermal cycles experienced by gas tungsten arc welding and laser beam welding Alloy 690 butt weldments, Corros. Sci. 51 (2009) 733–743.
79. G. Bao, K. Shinozaki, M. Inkyo, T. Miyoshi, M. Yamamoto, Y. Mahara, H. Watanabe, Modeling of precipitation and Cr depletion profiles of Inconel 600 during heat treatments and LSM procedure, J. Alloys Compd. 419 (2006) 118–125.
80. D.A. Akinlade, W.F. Caley, N.L. Richards, M.C. Chaturvedi, Microstructural response of an Al-modified Ni–Cr–Fe ternary alloy during thermal processing, Mater. Sci. Eng., A A 486 (2008) 626–633.
81. G.A. Young, T.E. Capobianco, M.A. Penik, B.W. Morris, J.J. Mcgee, The mechanism of ductility dip cracking in nickel-chromium alloys, Weld. J. 87 (2008) 31–43.
校內:2012-08-25公開