Nuclear Engineering and Technology

Korean Nuclear Society (한국원자력학회)
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Influence of Hold Time and Stress Ratio on Cyclic Creep Properties Under Controlled Tension Loading Cycles of Grade 91 Steel

  • Received : 2016.07.26
  • Accepted : 2016.11.28
  • Published : 2017.06.25
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Abstract

Influences of hold time and stress ratio on cyclic creep properties of Grade 91 steel were systemically investigated using a wide range of cyclic creep tests, which were performed with hold times (HTs) of 1 minute, 3 minutes, 5 minutes, 10 minutes, 20 minutes, and 30 minutes and stress ratios (R) of 0.5, 0.8, 0.85, 0.90, and 0.95 under tension loading cycles at $600^{\circ}C$. Under the influence of HT, the rupture time increased to HT = 5 minutes at R = 0.90 and R = 0.95, but there was no influence at R = 0.50, 0.80, and 0.85. The creep rate was constant regardless of an increase in the HT, except for the case of HT = 5 minutes at R = 0.90 and R = 0.95. Under the influence of stress ratio, the rupture time increased with an increase in the stress ratio, but the creep rate decreased. The cyclic creep led to a reduction in the rupture time and an acceleration in the creep rate compared with the case of monotonic creep. Cyclic creep was found to depend dominantly on the stress ratio rather than on the HT. Fracture surfaces displayed transgranular fractures resulting from microvoid coalescence, and the amount of microvoids increased with an increase in the stress ratio. Enhanced coarsening of the precipitates in the cyclic creep test specimens was found under all conditions.

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References

  1. W.G. Kim, J.Y. Park, S.J. Kim, J. Jang, Reliability assessment of creep rupturelife for Gr. 91 steel, Mater. Des. 51 (2013) 1045-1051. https://doi.org/10.1016/j.matdes.2013.05.013
  2. E. Issac Samual, B.K. Choudhary, K. Bhau Sankara Rao, Influence of post weld heat treatment on tensile properties of 9Cr-1Mo ferritic steel base metal, Mater. Sci. Technol. 23 (2007) 992-998. https://doi.org/10.1179/174328407X161295
  3. S.L. Mannan, S.C. Chetal, B. Raj, S.B. Bhoje, Selection of materials for prototype fast breeder reactor, Trans. Indian Inst. Met. 56 (2003) 155-178.
  4. B.K. Choudhary, V.S. Srinivasan, M.D. Mathew, Influence of strain rate and temperature on tensile properties of 9Cr-1Mo ferritic steel, Mater. High Temp. 28 (2011) 155-161.
  5. B.K. Choudhary, E. Issac Samual, Creep behavior of modified 9Cr-1Mo ferritic steel, J. Nucl. Mater. 412 (2011) 82-89. https://doi.org/10.1016/j.jnucmat.2011.02.024
  6. B. Raj, B.K. Choudhary, A perspective on creep and fatigue issues in sodiumcooled fast reactors, Trans. Indian Inst. Met. 63 (2010) 75-84. https://doi.org/10.1007/s12666-010-0011-3
  7. K. Kimura, Y. Toda, H. Kushima, K. Sawada, Creep strength of high chromium steel with ferrite matrix, in: I.A. Shibli, S.R. Holdsworth (Eds.), Proceedings of the 2nd ECCC Creep Conference on Creep & Fracture in High Temperature Components, Zurich ETD, 2009, pp. 935-949.
  8. V.S. Srinivasan, B.K. Choudhary, M.D. Mathew, T. Jayakumar, Long-term creep-rupture strength prediction for modified 9Cr-1Mo ferritic steel and type 316L(N) austenitic stainless steel, Mater. High Temp. 29 (2012) 41-48. https://doi.org/10.3184/096034012X13269690282656
  9. W.G. Kim, J.Y. Park, S.D. Hong, S.J. Kim, Probabilistic assessment of creep crack growth rate for Gr. 91 steel, Nucl. Eng. Des. 241 (2011) 3580-3586. https://doi.org/10.1016/j.nucengdes.2011.06.042
  10. D.K. Shetty, T. Mura, M. Meshii, Analysis of creep deformation under cyclic loading conditions, Mater. Sci. Eng. 20 (1975) 261-266. https://doi.org/10.1016/0025-5416(75)90158-5
  11. J. Zrnik, J.A. Wang, Y. Yu, L. Peijing, P. Hornak, Influence of cycling frequency on cyclic creep characteristics of nickel base single-crystal superalloy, Mater. Sci. Eng. A A234-A236 (1997) 884-888.
  12. J.H. Eom, D.H. Shin, S.W. Nam, Effects of stress amplitude and friction stress on cyclic creep deformation, J. Kor. Inst. Met. 20 (1982) 922-926.
  13. Y.K. Park, T.S. Kim, J.H. Choi, M.Y. Wee, A study on cyclic creep behavior of Zircaloy-4 at 0.3 Tm, J. Kor. Inst. Met. Mater. 38 (2000) 624-628.
  14. M. Boulbibane, A.R.S. Ponter, A method for the evaluation of design limits for structural materials in a cyclic state of creep, Eur. J. Mech. A Solid 21 (2002) 899-914. https://doi.org/10.1016/S0997-7538(02)01244-5
  15. H.D. Chandler, S. Kwofie, A description of cyclic creep under conditions of axial cyclic and mean stresses, Int. J. Fatigue 27 (2005) 541-545. https://doi.org/10.1016/j.ijfatigue.2004.09.009
  16. W.G. Kim, J.Y. Park, I.M.W. Ekaputra, S.J. Kim, J. Jang, Cyclic creep behavior under ten-tension loading cycles with hold time of modified 9Cr-1Mo steel, Mater. High Temp. 31 (2014) 249-257. https://doi.org/10.1179/1878641314Y.0000000021
  17. ASTM International, Standard test method for conducting creep, creep-rupture, and stress-rupture tests of metallic materials, ASTM (2011). E139-11.
  18. G. Qin, S.V. Hainsworth, A. Strang, P.F. Morris, P.D. Clarke, A.P. Backhouse, TEM studies of microstructural evolution in creep exposed E911, in: I.A. Shibli, S.R. Holdsworth (Eds.), Proceedings of the 2nd ECCC Creep Conf. on Creep & Fracture in High Temperature Components, Zurich ETD, 2009, pp. 889-899.

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