Cite this article as: |
Noora Hytönen, Zai-qing Que, Pentti Arffman, Jari Lydman, Pekka Nevasmaa, Ulla Ehrnstén, and Pål Efsing, Effect of weld microstructure on brittle fracture initiation in the thermally-aged boiling water reactor pressure vessel head weld metal, Int. J. Miner. Metall. Mater., 28(2021), No. 5, pp. 867-876. https://doi.org/10.1007/s12613-020-2226-6 |
Effects of the weld microstructure and inclusions on brittle fracture initiation are investigated in a thermally aged ferritic high-nickel weld of a reactor pressure vessel head from a decommissioned nuclear power plant. As-welded and reheated regions mainly consist of acicular and polygonal ferrite, respectively. Fractographic examination of Charpy V-notch impact toughness specimens reveals large inclusions (0.5–2.5 μm) at the brittle fracture primary initiation sites. High impact energies were measured for the specimens in which brittle fracture was initiated from a small inclusion or an inclusion away from the V-notch. The density, geometry, and chemical composition of the primary initiation inclusions were investigated. A brittle fracture crack initiates as a microcrack either within the multiphase oxide inclusions or from the debonded interfaces between the uncracked inclusions and weld metal matrix. Primary fracture sites can be determined in all the specimens tested in the lower part of the transition curve at and below the 41-J reference impact toughness energy but not above the mentioned value because of the changes in the fracture mechanism and resulting changes in the fracture appearance.
[1] |
P. Haušild, C. Berdin, and P. Bompard, Prediction of cleavage fracture for a low-alloy steel in the ductile-to-brittle transition temperature range, Mater. Sci. Eng. A, 391(2005), No. 1-2, p. 188.
|
[2] |
A.H. Cottrell, Theory of brittle facture in steel and similar metals, Trans. Metall. Soc. AIME, 212(1958), p. 192.
|
[3] |
P. Joly, L. Sun, P. Efsing, J.P. Massoud, F. Somville, R. Gerard, Y.H. An, and J. Bailey, Characterization of in-service thermal ageing effects in base materials and welds of the pressure vessel of a decommissioned PWR pressurizer, after 27 years of operation, [in] 19th International Conference on Environmental Degradation of Materials in Nuclear Power Systems-Water Reactors 2019, Boston, 2019, p. 392.
|
[4] |
K. Lindgren, M. Boåsen, K. Stiller, P. Efsing, and M. Thuvander, Evolution of precipitation in reactor pressure vessel steel welds under neutron irradiation, J. Nucl. Mater., 488(2017), p. 222. doi: 10.1016/j.jnucmat.2017.03.019
|
[5] |
Y.A. Nikolaev, A.V. Nikolaeva, A.M. Kryukov, V.I. Levit, and Y.N. Korolyov, Radiation embrittlement and thermal annealing behavior of Cr–Ni–Mo reactor pressure vessel materials, J. Nucl. Mater., 226(1995), No. 1-2, p. 144. doi: 10.1016/0022-3115(95)00097-6
|
[6] |
G.R. Odette and R.K. Nanstad, Predictive reactor pressure vessel steel irradiation embrittlement models: Issues and opportunities, JOM, 61(2009), No. 7, p. 17. doi: 10.1007/s11837-009-0097-4
|
[7] |
R.S. Xing, D.J. Yu, G.F. Xie, Z.H. Yang, X.X. Wang, and X. Chen, Effect of thermal ageing on mechanical properties of a bainitic forging steels for reactor pressure vessel, Mater. Sci. Eng. A, 720(2018), p. 169. doi: 10.1016/j.msea.2018.02.036
|
[8] |
K. Wallin, M. Yamamoto, and U. Ehrnstén, Location of initiation sites in fracture toughness testing specimens: The effect of size and side grooves, [in] Proceedings of the ASME 2016 Pressure Vessels and Piping Conference, Volume 1B: Codes and Standards, Vancouver, 2016, art. No. V01BT01A011.
|
[9] |
A.A. Griffith, The phenomena of rupture and flow in solids, Philos. Trans. R. Soc. London, 221(1921), p. 163. doi: 10.1098/rsta.1921.0006
|
[10] |
A. Pineau, A.A. Benzerga, and T. Pardoen, Failure of metals I: Brittle and ductile fracture, Acta Mater., 107(2016), p. 424. doi: 10.1016/j.actamat.2015.12.034
|
[11] |
W. Weibull, A statistical theory of the strength of materials, [in] Generalstabens Litografiska Anstalts Förlag, Stockholm, 1939.
|
[12] |
W. Weibull, A statistical distribution function of wide applicability, J. Appl. Mech., 18(1951), p. 293. doi: 10.1115/1.4010337
|
[13] |
F.M. Beremin, A. Pineau, F. Mudry, J.C. Devaux, Y. D’Escatha, and P. Ledermann, A local criterion for cleavage fracture of a nuclear pressure vessel steel, Metall. Trans. A, 14(1983), p. 2277. doi: 10.1007/BF02663302
|
[14] |
C.L. Briant and S.K. Banerji, Intergranular failure in steel: The role of grain-boundary composition, Int. Met. Rev., 23(1978), No. 1, p. 164. doi: 10.1179/imr.1978.23.1.164
|
[15] |
R.W. Hertzberg, R.P. Vinci, and J.L. Hertzberg, Deformation and Fracture Mechanics of Engineering Materials, 5th ed., John Wiley & Sons, Chichester, 2013. p. 299.
|
[16] |
J.D. Landes and D.H. Shaffer, Statistical characterization of fracture in the transition region, [in] P. Paris ed., Fracture Mechanics, ASTM International, West Conshohocken, 1980. p. 368.
|
[17] |
K. Wallin, Fracture Toughness of Engineering Materials: Estimation and Application, FESI Publishing, 2011.
|
[18] |
P. Bowen, S.G. Druce, and J.F. Knott, Effects of microstructure on cleavage fracture in pressure vessel steel, Acta Metall., 34(1986), No. 6, p. 1121. doi: 10.1016/0001-6160(86)90222-1
|
[19] |
H. Hein, J. Kobiela, M. Brumovsky, C. Huotilainen, J. Lydman, B. Marini, B. Radiguet, O. Startsev, M. Serrano Garcia, R. Hernandez Pascual, F. Roeder, and H.W. Viehrig, Addressing of specific uncertainties in determination of RPV fracture toughness in the SOTERIA project, [in] Fontevraud 9-Contribution of Materials Investigations and Operating Experience to Light Water NPPs’ Safety, Performance and Reliability, Avignon, 2018.
|
[20] |
M. Boåsen, Modeling of Structural Integrity of Aged Low Alloy Steels Using Non-Local Mechanics, [Dissertation], KTH Royal Institute of Technology, Stockholm, Sweden, 2020.
|
[21] |
C.A. Hippsley and S.G. Druce, The influence of phosphorus segregation to particle/matrix interfaces on ductile fracture in a high strength steel, Acta Metall., 31(1983), No. 11, p. 1861. doi: 10.1016/0001-6160(83)90132-3
|
[22] |
H. Bhadeshia and R. Honeycombe, Steels: Microstructure and Properties, 4th ed. Elsevier Ltd., Cambridge, 2017.
|
[23] |
G.M. Evans, Effect of manganese on the microstructure and properties of all-weld-metal deposits, Welding Res. Suppl., 59(1980), No. 3, p. 67.
|
[24] |
J.H. Shim, Y.J. Oh, J.Y. Suh, Y.W. Cho, J.D. Shim, J.S. Byun, and D.N. Lee, Ferrite nucleation potency of non-metallic inclusions in medium carbon steels, Acta Mater., 49(2001), No. 12, p. 2115. doi: 10.1016/S1359-6454(01)00134-3
|
[25] |
B.A. Gurovich, E.A. Kulehsova, Y.I. Shtrombakh, O.O. Zabusov, and E.A. Krasikov, Intergranular and intragranular phosphorus segregation in russian pressure vessel steels due to neutron irradiation, J. Nucl. Mater., 279(2000), No. 2-3, p. 259. doi: 10.1016/S0022-3115(00)00007-6
|
[26] |
D.J. Sprouster, J. Sinsheimer, E. Dooryhee, S.K. Ghose, P. Wells, T. Stan, N. Almirall, G.R. Odette, and L.E. Ecker, Structural characterization of nanoscale intermetallic precipitates in highly neutron irradiated reactor pressure vessel steels, Scripta Mater., 113(2016), p. 18. doi: 10.1016/j.scriptamat.2015.10.019
|
[27] |
K. Lindgren, M. Boåsen, K. Stiller, P. Efsing, and M. Thuvander, Cluster formation in in-service thermally aged pressurizer welds, J. Nucl. Mater., 504(2018), p. 23. doi: 10.1016/j.jnucmat.2018.03.017
|
[28] |
J.S. Byun, J.H. Shim, Y.W. Cho, and D.N. Lee, Non-metallic inclusion and intragranular nucleation of ferrite in Ti-killed C–Mn steel, Acta Mater., 51(2003), No. 6, p. 1593. doi: 10.1016/S1359-6454(02)00560-8
|
[29] |
D.S. Sarma, A.V. Karasev, and P.G. Jönsson, On the role of non-metallic incluisons in the nucleation of acicular ferrite in steels, ISIJ Int., 49(2009), No. 7, p. 1063. doi: 10.2355/isijinternational.49.1063
|
[30] |
U. Zerbst, R.A. Ainsworth, H.T. Beier, H.T. Pisarski, Z.L. Zhang, K. Nikbin, T. Nitschke-Pagel, S. Münstermann, P. Kucharczyk, and D. Klingbeil, Review on fracture and crack propagation in weldments—A fracture mechanics perspective, Eng. Fract. Mech., 132(2014), p. 200. doi: 10.1016/j.engfracmech.2014.05.012
|
[31] |
M. Boåsen, K. Lindgren, J. Rouden, M. Öberg, J. Faleskog, M. Thuvander, and P. Efsing, Thermal ageing of low alloy steel weldments from a Swedish nuclear power plant—A study of mechanical properties, [in] Fontevraud 9-Contribution of Materials Investigations and Operating Experience to Light Water NPPs’ Safety, Performance and Reliability, Avignon, 2018.
|
[32] |
M.K. Miller, K.A. Powers, R.K. Nanstad, and P. Efsing, Atom probe tomography characterizations of high nickel, low copper surveillance RPV welds irradiated to high fluences, J. Nucl. Mater., 437(2013), No. 1-3, p. 107. doi: 10.1016/j.jnucmat.2013.01.312
|
[33] |
Finnish Standards Association, ISO 148-1: 2016: Metallic Materials—Charpy Pendulum Impact Test —Part 1: Test Method, Standard, Finnish Standards Association, West Conshohocken, 2016.
|
[34] |
ASTM International, ASTM E185 -16: Standard Practice for Design of Surveillance Programs for Light-Water Moderated Nuclear Power Reactor Vessels, Standard, ASTM International, West Conshohocken, 2018.
|
[35] |
N. Hytönen, Effect of Microstructure on Brittle Fracture Initiation in a Reactor Pressure Vessel Weld Metal [Dissertation], University of Tampere, Tampere, 2019.
|
[36] |
S.J. Jones and H.K.D.H. Bhadeshia, Competitive formation of inter- and intragranularly nucleated ferrite, Metall. Mater. Trans. A, 28(1997), No. 10, p. 2005. doi: 10.1007/s11661-997-0157-8
|
[37] |
T.L. Anderson, Fracture Mechanics Fundamentals and Applications, 2nd ed., CRC Press, Boca Raton, 1995.
|
[38] |
M. Kroon and J. Faleskog, Micromechanics of cleavage fracture initiation in ferritic steels by carbide cracking, J. Mech. Phys. Solids, 53(2005), No. 1, p. 171. doi: 10.1016/j.jmps.2004.05.008
|
[39] |
L.F. Zhang, B. Radiguet, P. Todeschini, C. Domain, Y. Shen, and P. Pareige, Investigation of solute segregation behaviour using a correlative EBSD/TKD/APT methodology in a 16MND5 weld, J. Nucl. Mater., 523(2019), p. 434. doi: 10.1016/j.jnucmat.2019.06.002
|