Design stress evaluation based on strain-rate sensitivity analysis for nickel alloys used in the very-high temperature nuclear system

Kun Mo, Hsiao Ming Tung, Xiang Chen, Yang Zhao, James F. Stubbins

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Both Alloy 617 and Alloy 230 have been considered the most promising structural materials for the Very High Temperature Reactor (VHTR). In this study, mechanical properties of both alloys were examined by performing tensile tests at three different strain rates and at temperatures up to 1000°C. This range covers time-dependent (plasticity) to time-independent (creep) deformations. Strain-rate sensitivity analysis for each alloy was conducted in order to approximate the long-term flow stresses. The strain-rate sensitivities for the 0.2% flow stress were found to be temperature independent (m ≈ 0) at temperatures ranging from room temperature to 700°C due to dynamic strain aging. At elevated temperatures (800-1000°C), the strain-rate sensitivity significantly increased (m > 0.1). Compared to Alloy 617, Alloy 230 displayed higher strain-rate sensitivities at high temperatures. This leads to a lower estimated long-term flow stresses. Results of this analysis were used to evaluate current American Society of Mechanical Engineers (ASME) allowable design limits. According to the comparison with the estimated flow stresses, the allowable design stresses in ASME B&PV Code for either alloy did not provide adequate degradation estimation for the possible long-term service life in VHTR. However, rupture stresses for Alloy 617, developed in ASME code case N-47-28, can generally satisfy the safety margin estimated in the study following the strain-rate sensitivity analysis. Nevertheless, additional material development studies might be required, since the design parameters for rupture stresses are constrained such that current VHTR conceptual designs cannot satisfy the limits.

Original languageEnglish (US)
Title of host publicationInternational Conference on the Physics of Reactors 2012, PHYSOR 2012
Subtitle of host publicationAdvances in Reactor Physics
Pages4244-4254
Number of pages11
StatePublished - Dec 6 2012
EventInternational Conference on the Physics of Reactors 2012: Advances in Reactor Physics, PHYSOR 2012 - Knoxville, TN, United States
Duration: Apr 15 2012Apr 20 2012

Publication series

NameInternational Conference on the Physics of Reactors 2012, PHYSOR 2012: Advances in Reactor Physics
Volume5

Other

OtherInternational Conference on the Physics of Reactors 2012: Advances in Reactor Physics, PHYSOR 2012
CountryUnited States
CityKnoxville, TN
Period4/15/124/20/12

Fingerprint

Nickel alloys
Sensitivity analysis
Strain rate
Plastic flow
High temperature gas reactors
Temperature
Engineers
Conceptual design
Service life
Plasticity
Creep
Aging of materials
Degradation
Mechanical properties

Keywords

  • Alloy 230
  • Alloy 617
  • Design stress
  • Strain-rate sensitive
  • VHTR

ASJC Scopus subject areas

  • Nuclear Energy and Engineering

Cite this

Mo, K., Tung, H. M., Chen, X., Zhao, Y., & Stubbins, J. F. (2012). Design stress evaluation based on strain-rate sensitivity analysis for nickel alloys used in the very-high temperature nuclear system. In International Conference on the Physics of Reactors 2012, PHYSOR 2012: Advances in Reactor Physics (pp. 4244-4254). (International Conference on the Physics of Reactors 2012, PHYSOR 2012: Advances in Reactor Physics; Vol. 5).

Design stress evaluation based on strain-rate sensitivity analysis for nickel alloys used in the very-high temperature nuclear system. / Mo, Kun; Tung, Hsiao Ming; Chen, Xiang; Zhao, Yang; Stubbins, James F.

International Conference on the Physics of Reactors 2012, PHYSOR 2012: Advances in Reactor Physics. 2012. p. 4244-4254 (International Conference on the Physics of Reactors 2012, PHYSOR 2012: Advances in Reactor Physics; Vol. 5).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Mo, K, Tung, HM, Chen, X, Zhao, Y & Stubbins, JF 2012, Design stress evaluation based on strain-rate sensitivity analysis for nickel alloys used in the very-high temperature nuclear system. in International Conference on the Physics of Reactors 2012, PHYSOR 2012: Advances in Reactor Physics. International Conference on the Physics of Reactors 2012, PHYSOR 2012: Advances in Reactor Physics, vol. 5, pp. 4244-4254, International Conference on the Physics of Reactors 2012: Advances in Reactor Physics, PHYSOR 2012, Knoxville, TN, United States, 4/15/12.
Mo K, Tung HM, Chen X, Zhao Y, Stubbins JF. Design stress evaluation based on strain-rate sensitivity analysis for nickel alloys used in the very-high temperature nuclear system. In International Conference on the Physics of Reactors 2012, PHYSOR 2012: Advances in Reactor Physics. 2012. p. 4244-4254. (International Conference on the Physics of Reactors 2012, PHYSOR 2012: Advances in Reactor Physics).
Mo, Kun ; Tung, Hsiao Ming ; Chen, Xiang ; Zhao, Yang ; Stubbins, James F. / Design stress evaluation based on strain-rate sensitivity analysis for nickel alloys used in the very-high temperature nuclear system. International Conference on the Physics of Reactors 2012, PHYSOR 2012: Advances in Reactor Physics. 2012. pp. 4244-4254 (International Conference on the Physics of Reactors 2012, PHYSOR 2012: Advances in Reactor Physics).
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