由前期的研究顯示出冷加工過後的合金 600在攝氏 200 度模擬 BWR 水質的飽和空氣水環境下具有藍脆(Blue brittleness)效應。藍脆為動態應變時效(Dynamic strain aging，簡稱DSA)的特徵之一。藍脆現象的出現，表示金屬材料會提前頸縮，為機械性質上的劣化行為。所以得知動態應變時效如何影響不同冷加工量合金 600的機械性質為重要研究方向。本研究主要進一步探討合金 600在模擬 BWR 加氫水化學(Hydrogen water chemistry, 簡稱HWC)水質環境下的動態應變時效特性和機械性質的影響。利用在加氫水化學的水質環境下慢速拉伸試驗(Slow strain rate tensile, 簡稱SSRT)，可以得到應力應變曲線圖(Stress-strain curve diagram)，以用來判斷機械性質。故本研究目標在以應力-應變曲線來探討加氫水化學中氫在動態應變時效現象中扮演了何種角色，與飽和空氣水環境中進行拉伸是否具有不同的劣化機制。為了能準確判斷動態應變時效中差排和溶質原子交互作用的影響，採用一組單軸拉伸冷加工去做塑性變形來確保試片加工量的均勻性。用慢速拉伸試驗以應變速率10-6/s，來觀察加氫水環路的影響。再改變不同的冷加工量和溫度，來觀察動態應變時效影響合金 600機械性質行為。在HWC下, 已經發現機械性質會有已下幾種現象: 藍脆、有D型態的鋸齒流應力、在單軸拉伸冷加工的試片發生了應變局部化促發破裂現象和在攝氏 300度下有最低的截面積縮減率。

In previous research, the phenomenon of blue brittleness occurred on the cold-rolled Alloy 600 tensile test in simulated BWR air-saturated coolant environments at 200℃. Blue brittleness is the manifestation of dynamic strain ageing (DSA). When blue brittleness of metal occurred, Alloy 600 would be necking early which indicated degradation of mechanical properties. The objectives of this study are to understand the characteristics of DSA observed on Alloy 600 under simulated BWR coolant environments with hydrogen water chemistry (HWC) and its influence on mechanical properties. Stress-strain curves were obtained from the slow strain rate tensile (SSRT) test to evaluate mechanical properties. Cold work by uniaxial tension can produce specimens with uniform plastic deformation, by which the interaction of solute atoms with dislocations can be studied when DSA occurred. Effects of HWC on DSA can be understood from tensile test of different amount of cold work and temperature at a strain rate of 10-6/s. The effect of mechanical properties in HWC were investigated, such as: Blue brittleness, the type D serrations, the intense strain-localization-induced fracture for cold-worked specimens by uniaxial tension and the minimum value of reduction of area at 300℃.

摘要............................................................................................................................................ I
Abstract ..................................................................................................................................... II
致謝.......................................................................................................................................... III
List of Tables ............................................................................................................................ VI
List of Figures ........................................................................................................................ VII
Chapter 1 Introduction ............................................................................................................... 1
Chapter 2 Literature Review ...................................................................................................... 2
2.1 Nickel-base Inconel 600 alloy ............................................................................................. 2
2.1.1 Types of carbides .............................................................................................................. 4
2.1.2 Oxide films on nickel-base Inconel Alloy 600 ................................................................. 5
Fig. 2.4 Model for the mechanism of the formation of the passive film on Ni−Cr−Fe alloy in
high temperature and high pressure water ................................................................................. 8
2.1 Dynamic strain aging (DSA) ............................................................................................... 9
2.11 General aspects .................................................................................................................. 9
2.1.2 Types of serrated flows due to DSA ................................................................................. 9
2.1.3 Models of DSA ............................................................................................................... 13
2.2 DSA in nickel-base alloys .................................................................................................. 17
2.3 Suzuki segregation ............................................................................................................. 20
Chapter 3 Experimental Procedures ......................................................................................... 21
3.1 Specimen Preparation ........................................................................................................ 21
3.2 Slow strain rate tensile (SSRT) test ................................................................................... 24
3.3 Characteristic Methods ...................................................................................................... 26
3.3.1 Optical Microscope (OM) ............................................................................................... 26
V
3.3.2 Scanning Electron Microscope (SEM) ........................................................................... 26
3.3.3 Transmission Electron Microscope (TEM) ..................................................................... 26
Chapter 4 Results ..................................................................................................................... 27
4.1 Microstructure .................................................................................................................... 27
4.2 Serrated flow in the stress-strain (σ-ɛ) curves .................................................................... 35
4.3 Mechanical properties in the DSA temperature range ....................................................... 41
4.4 Fractography ...................................................................................................................... 46
Chapter 5 Discussion ............................................................................................................... 51
5.1 Microstructural characterization ........................................................................................ 51
5.2 Effect of DSA on mechanical properties of Alloy 600 ...................................................... 52
5.3 Characteristics of serrated flow ......................................................................................... 61
5.4 Effect of environment on DSA behavior............................................................................ 63
Chapter 6 Conclusions ............................................................................................................. 70
Reference

[1] Y.-T. Huang, "冷加工對鎳基合金 600 於模擬 BWR 水質之動態應變時效影
響研究" 清華大學工程與系統科學系學位論文 (2013) 1.
[2] H. Hänninen, M. Ivanchenko, Y. Yagodzinskyy, V. Nevdacha, U. Ehrnstén, P.
Aaltonen, TR Allen, PJ King and L. Nelson (Eds.), Proceedings of the 12th
International Conference on Environmental Degradation of Materials in Nuclear Power
Systems-Water Reactors, TMS, Warrendale, PA, USA, 2005.
[3] I.S. Kim, M. Chaturvedi, "Serrated flow in Inconel 625" Trans. Jpn. Inst. Met. 28/3
(1987) 205.
[4] A. Cottrell, "LXXXVI. A note on the Portevin-Le Chatelier effect" Philosophical
Magazine 44/355 (1953) 829.
[5] P. McCormick, "Theory of flow localisation due to dynamic strain ageing" Acta
Metallurgica 36/12 (1988) 3061.
[6] L. Kubin, K. Chihab and Y. Estrin, "The rate dependence of the Portevin-Le
Chatelier effect" Acta Metallurgica 36/10 (1988) 2707.
[7] L. Kubin and Y. Estrin, "Evolution of dislocation densities and the critical
conditions for the Portevin-Le Chatelier effect" Acta metallurgica et materialia 38/5
(1990) 697.
[8] Y. Estrin, "Dislocation theory based constitutive modelling: foundations and
applications" Journal of Materials Processing Technology 80 (1998) 33.
[9] Y. Estrin and P. McCormick, "Modelling the transient flow behaviour of dynamic
strain ageing materials" Acta metallurgica et materialia 39/12 (1991) 2977.
[10] S.M. Corporation, "Inconel alloy 600" (2008).
[11] A.M. Handbook.
73
[12] J. Panter, B. Viguier, J.-M. Cloué, M. Foucault, P. Combrade and E. Andrieu,
"Influence of oxide films on primary water stress corrosion cracking initiation of alloy
600" Journal of nuclear materials 348/1 (2006) 213.
[13] A. Machet, A. Galtayries, S. Zanna, L. Klein, V. Maurice, P. Jolivet, M. Foucault,
P. Combrade, P. Scott and P. Marcus, "XPS and STM study of the growth and structure
of passive films in high temperature water on a nickel-base alloy" Electrochimica Acta
49/22 (2004) 3957.
[14] P. Rodriguez, "Serrated plastic flow" Bulletin of Materials Science 6/4 (1984) 653.
[15] J. King, C. You and J. Knott, "Serrated yielding and the localized shear failure
mode in aluminium alloys" Acta Metallurgica 29/9 (1981) 1553.
[16] J. Butler, "Lüders front propagation in low carbon steels" Journal of the Mechanics
and Physics of Solids 10/4 (1962) 313.
[17] H. Ait-Amokhtar, C. Fressengeas and S. Boudrahem, "The dynamics of Portevin–
Le Chatelier bands in an Al–Mg alloy from infrared thermography" Materials Science
and Engineering: A 488/1 (2008) 540.
[18] Q. Zhang, Z. Jiang, H. Jiang, Z. Chen and X. Wu, "On the propagation and
pulsation of Portevin-Le Chatelier deformation bands: An experimental study with
digital speckle pattern metrology" International journal of plasticity 21/11 (2005) 2150.
[19] B. Russell, "Repeated yielding in tin bronze alloys" Philosophical Magazine 8/88
(1963) 615.
[20] P. Worthington and B. Brindley, "Serrated yielding in substitutional alloys"
Philosophical Magazine 19/162 (1969) 1175.
[21] W. Chaenock, "The initiation of serrated yielding at elevated temperatures"
Philosophical Magazine 20/164 (1969) 427.
[22] Z. Jiang, Q. Zhang, H. Jiang, Z. Chen and X. Wu, "Spatial characteristics of the
74
Portevin-Le Chatelier deformation bands in Al-4at% Cu polycrystals" Materials
Science and Engineering: A 403/1 (2005) 154.
[23] P. Hähner and E. Rizzi, "On the kinematics of Portevin–Le Chatelier bands:
theoretical and numerical modelling" Acta Materialia 51/12 (2003) 3385.
[24] A. Van Den Beukel, "On the mechanism of serrated yielding and dynamic strain
ageing" Acta Metallurgica 28/7 (1980) 965.
[25] P. Penning, "Mathematics of the portevin-le chatelier effect" Acta Metallurgica
20/10 (1972) 1169.
[26] M. Lebyodkin, Y. Brechet, Y. Estrin and L. Kubin, "Statistical behaviour and strain
localization patterns in the Portevin-Le Chatelier effect" Acta materialia 44/11 (1996)
4531.
[27] Y. Nakada and A. Keh, "Serrated flow in Ni-C alloys" Acta Metallurgica 18/4
(1970) 437.
[28] U. Kocks, R. Cook and
alloys" Acta Metallurgica 33/4 (1985) 623.
[29] S. Kinoshita, P. Wray and G. Horne, "Some observations on the Portevin-Le
Chatelier effect in Iron" AIME MET SOC TRANS 233 (1965) 1902.
[30] A. Kimura and H. Birnbaum, "Anomalous strain rate dependence of the serrated
1343.
[31] S.H. Hong, H.Y. Kim, J.S. Jang and I.H. Kuk, "Dynamic strain aging behavior of
Inconel 600 alloy" Superalloys 1996 (1996) 401.
[32] V. Shankar, M. Valsan, K.B.S. Rao and S. Mannan, "Effects of temperature and
strain rate on tensile properties and activation energy for dynamic strain aging in alloy
625" Metallurgical and Materials Transactions A 35/10 (2004) 3129.
75
[33] C. Hale, W. Rollings and M. Weaver, "Activation energy calculations for
discontinuous yielding in Inconel 718SPF" Materials Science and Engineering: A 300/1
(2001) 153.
[34] K. Gopinath, A. Gogia, S. Kamat and U. Ramamurty, "Dynamic strain ageing in
Ni-base superalloy 720Li" Acta Materialia 57/4 (2009) 1243.
[35] R. Hayes and W. Hayes, "On the mechanism of delayed discontinuous plastic flow
in an age-hardened nickel alloy" Acta Metallurgica 30/7 (1982) 1295.
[36] A. Chiba and M.S. Kim, "Suzuki segregation and dislocation locking in
supersaturated Co-Ni-based alloy" Materials transactions-JIM 42/10 (2001) 2112.
[37] M. Fujita, Y. Kaneko, A. Nohara, H. Saka, R. Zauter and H. Mughrabi,
"Temperature dependence of the dissociation width of dislocations in a commercial 304
L stainless steel" ISIJ Int.(Japan) 34/8 (1994) 697.
[38] B.G. Mendis, I.P. Jones and R.E. Smallman, "Suzuki segregation in a binary CuSi alloy" Journal of electron microscopy 53/4 (2004) 311.
[39] G. Han, I. Jones and R. Smallman, "Direct evidence for Suzuki segregation and
Cottrell pinning in MP159 superalloy obtained by FEG (S) TEM/EDX" Acta materialia
51/10 (2003) 2731.
[40] Y. Kaneko, K. Kaneko, A. Nohara and H. Saka, "Evidence for Suzuki effect in an
Fe-Ni-Cr austenitic stainless steel" Philosophical Magazine A 71/2 (1995) 399.
[41] H. Wang, C. Berdin, M. Mazière, S. Forest, C. Prioul, A. Parrot and P. Le-Delliou,
"Portevin–Le Chatelier (PLC) instabilities and slant fracture in C–Mn steel round
tensile specimens" Scripta Materialia 64/5 (2011) 430.
[42] S. Zhang, D. Sun, Y. Fu and H. Du, "Toughness measurement of ceramic thin films
by two-step uniaxial tensile method" Thin solid films 469 (2004) 233.