Irradiation Hardening and Indentation Size Effect of the 304NG Stainless Steels After Triple Beam Irradiation
The nuclear grade 304NG stainless steel (SS) has been developed in the past several decades as the new generation of internal material in light water reactors. The irradiation effects of domestic 304NG SS were simulated by the triple ion beam irradiation on the heavy ion, hydrogen and helium triple ion beam irradiation platform at China institute of Atomic Energy. The irradiation experiments were carried out with various doses (6, 15, 30 and 150 dpa at 300 ℃) and temperatures (300, 350, 400, 450 ℃ with 6 dpa). The depth-dependent hardness and elastic modulus of the specimens before and after irradiation were measured by nanoindentation with the continuous stiffness measurement technique. For the specimens irradiated at 300 ℃, the hardness generally increases with the increasing dose. The depth-dependent hardness in the micro-indentation region (indentation depth h > 100 nm) of those specimens with dose less than 30 dpa can be well explained by Nix & Gao formulae of the indentation size effect. For the specimens irradiated at different temperatures, the hardening effect can be observed for all specimens for indentation depth beyond 1 μm and the hardness decreases with increasing irradiation temperature. However, as the irradiation temperature elevates or the dose increases up to 150 dpa, the hardness for the indentation depth h < 500 nm deviates significantly from the projection of the Nix & Gao model. The surface morphology observed by SEM and the S parameters extracted from the slow positron annihilation Doppler broadening indicate that the drastic reduction of hardness those specimens with indentation depth h < 500 nm can be attributed to the change of surface morphology.
Keywords304NG stainless steel Triple beam irradiation Nanoindentation Indentation size effect Slow positron doppler broadening
The authors acknowledge the support from the National Science Foundation of China under Grant No. 11005158 and 9112600, and the National major project of science and technology under Grant No. 2012ZX06004-005-005.
- 1.H. Wolfgang, Materials for nuclear plants: from safe design to residual life assessments (Springer, London, 2013)Google Scholar
- 3.Y. Wen, X.-P. Lai, Y.-G. Duan, E. Jiang, G.-F. Li, B. Xu, B. Gong, Research on application performance of nitrogen-containing stainless steel 304NG made in China. Nucl. Power Eng. 28(z1), 40–43 (2007). (in Chinese)Google Scholar
- 5.J.E. Alexander, et al., Alternative alloys for BWR piping applications, Final Report, NP-2671-LD, General Electric Company, October (1982)Google Scholar
- 6.R.W. Weeks, Stress-corrosion cracking in BWR and PWR piping, Proceedings of the International Symposium on Environmental Degradation of Materials in Nuclear Power Systems—Water Reactors: Myrtle Beach, South Carolina, August 22–25, (1983)Google Scholar
- 8.ASTM E521-16, Standard practice for investigating the effects of neutron radiation damage using charged-particle irradiation, ASTM International, West Conshohocken, PA, (2016). www.astm.org
- 9.G.S. Was, Fundamentals of radiation materials science: metals and alloys (Springer, Berlin, 2007)Google Scholar
- 12.D.-Q. Yuan, Y.-N. Zhen, Y. Zuo, P. Fan, D.-M. Zhou, Q.-L. Zhang, X.-Q. Ma, B.-Q. Cui, L.-H. Chen, W.-S. Jiang, Y.-C. Wu, Q.-Y. Huan, L. Pen, X.-Z. Cao, B.-Y. Wang, L. Wei, S.-Y. Zhu, Synergistic effect of triple ion beams on radiation damage in CLAM steel. Chin. Phys. Lett. 31, 2012–2014 (2014)Google Scholar
- 23.Z. Wang, Influences of sample preparation on the indentation size effect and nanoindentation pop-in on nickel. Ph.D. dissertation, University of Tennessee, 2012Google Scholar