Hardening of ODS ferritic steels under irradiation with high-energy heavy ions

Ding, Zhaonan; Zhang, C.H.; Yang, Yitao; Song, Yingwei; Kimura, Akihiko; Jang, Jinsung

doi:10.1016/j.jnucmat.2017.05.040

Cited by 46 publications

(6 citation statements)

References 38 publications

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“…The Vickers micro-hardness data are further compared with the nano-hardness obtained previously by nano-indentation tests from the same CLF-1 specimens [16]. As shown in figure 6, the Vickers micro-hardness data reveal a linear A similar linear relationship was found for various steels in our previous work [22,23] and also by Yabuuchi et al [10]. The projection contact area is used in the analysis of nanoindentation data, while the residual projection area is used in Vickers hardness analysis [9].…”

Section: Irradiation Hardeningsupporting

confidence: 67%

Vickers hardness change of the Chinese low-activation ferritic/martensitic steel CLF-1 irradiated with high-energy heavy ions

Ding

Zhang

Yang

et al. 2020

Plasma Sci. Technol.

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In the present work, the irradiation hardening behavior of a Chinese low-activation ferritic/ martensitic steel CLF-1, a candidate for fusion reactor blankets, is studied. Specimens were irradiated with high-energy 14 N and 56 Fe ions at the terminal of a cyclotron to three successively increasing damage levels of 0.05, 0.1 and 0.2 displacements per atom (dpa) at about −50 °C. The energy of the incident ions was dispersed to 11 successively decreasing grades using an energy degrader, thereby generating an atomic displacement damage plateau in the specimens from the surface to a depth of 25 μm, which is sufficiently broad for the Vickers hardness test. Eight different loads (i.e. 98 mN, 196 mN, 490 mN, 980 mN, 1.96 N, 4.9 N, 9.8 N and 19.6 N) were applied to the specimens to obtain the depth profiles of the Vickers hardness by using a microhardness tester. Hardening was observable at the lowest damage level, and increased with increasing irradiation dose. A power-law correlation of the Vickers hardness with the damage level (HV 0 =1.49+0.76 dpa 0.31 ) is proposed. Testing with a nano-indentation technique was also performed, and a linear relationship between the Vickers micro-hardness and the nanohardness (HV 0 =0.83H 0 ) was observed. A comparison with other RAFM steels (CLAM, JLF-1, F82H, EUROFER97 etc.) under neutron or charged particle irradiation conditions shows that most of the RAFM steels exhibit similar power-law exponents in the dose dependence of irradiation hardening. The difference in the irradiation hardening may be attributed to differences in microstructure prior to irradiation.

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Section: Irradiation Hardeningsupporting

confidence: 67%

Vickers hardness change of the Chinese low-activation ferritic/martensitic steel CLF-1 irradiated with high-energy heavy ions

Ding

Zhang

Yang

et al. 2020

Plasma Sci. Technol.

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“…This adaptability to enhance precision with additional data input demonstrates the neural networks' robustness in modeling complex relationships, even when they deviate from linearity. Previous studies posited that the relationship between nanoindentation hardness and Vickers hardness is generally linear [59][60][61]. Observations from Figure 6 also suggest an approximately linear relationship.…”

Section: Validation Of Nanoindentation-vickers Hardness Dnn Modelmentioning

confidence: 54%

Leveraging Deep Neural Networks for Estimating Vickers Hardness from Nanoindentation Hardness

Niu,

Miao,

Guo

et al. 2023

Materials

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This research presents a comprehensive analysis of deep neural network models (DNNs) for the precise prediction of Vickers hardness (HV) in nitrided and carburized M50NiL steel samples, with hardness values spanning from 400 to 1000 HV. By conducting rigorous experimentation and obtaining corresponding nanoindentation data, we evaluated the performance of four distinct neural network architectures: Multilayer Perceptron (MLP), Convolutional Neural Network (CNN), Long Short-Term Memory network (LSTM), and Transformer. Our findings reveal that MLP and LSTM models excel in predictive accuracy and efficiency, with MLP showing exceptional iteration efficiency and predictive precision. The study validates models for broad application in various steel types and confirms nanoindentation as an effective direct measure for HV hardness in thin films and gradient-variable regions. This work contributes a validated and versatile approach to the hardness assessment of thin-film materials and those with intricate microstructures, enhancing material characterization and potential application in advanced material engineering.

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“…In the present work, multi-factors in initial microstructure such as precipitates, grains, dislocations and bubbles puzzles the analysis. For precipitates, in our previous papers, dispersed nanofeature precipitates (a few nanometers) with a high number density (above 1 × 10 21 m −3 ), such as oxides in ODS steels, will provide sufficient sink strength for damage evolution [39,66]. Because the precipitates in the present work are of large size and low number density, they will not be considered here.…”

Section: Discussionmentioning

confidence: 94%

“…Despite the kinetic rate theory analysis, experiments were attempted to give direct evidence of the effect of the initial microstructure on irradiation effects [39,66,68]. In our previous work, sinks could change the defect production, as well as the irradiation hardening, and a linear relation between sink strength and hardening was observed [39].…”

Section: Discussionmentioning

confidence: 99%

Effect of cold work deformationon irradiation hardening of vanadium alloys

et al. 2022

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Vanadium alloys have been regarded as the promising candidate structure materials for the advanced blanket concept in fusion reactor due to the low activation, good high-temperature strength and especially the compatibility with liquid lithium. In the present work, six kinds of V-5Cr-5Ti alloys under heavily cold work with deformation amounts of 40%, 60% and 80%, and/or subsequent annealing were investigated. Irradiation damage of 0.1, 0.3 and 0.5 dpa was introduced in both specimens by using 352.8 MeV Fe ions at 100 ℃. Electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM) were used to investigate pre-irradiation microstructures such as grains, dislocations, precipitates, and bubbles. XRD was used to evaluate the pre-existing dislocation density and TEM was used to image irradiation defects. Change in hardness was evaluated by using micro-hardness tests. Before irradiation, hardness increased with increasing deformation amount but decreased after subsequent annealing. Dislocation cells turning into sub-grains with low-angle boundaries was observed while deformation amount reaching 80% in cold-worked specimens. After irradiation, hardening was observed in all specimens and doses, and a power-law relation was observed in dose dependent hardening. Effect of initial microstructure on irradiation hardening was discussed in terms of sink strength while ignoring grains and precipitates due to their large size. Pre-existing bubbles could effectively reduce irradiation hardening while compared with previous papers. Meanwhile, with increasing sink strength of dislocations, hardening decreased in a different manner in cold-worked and annealed specimens. Irradiation defects in some specimens were investigated to clarify the inherent mechanism in the relation between initial microstructures and irradiation hardening.

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Hardening of ODS ferritic steels under irradiation with high-energy heavy ions

Cited by 46 publications

References 38 publications

Vickers hardness change of the Chinese low-activation ferritic/martensitic steel CLF-1 irradiated with high-energy heavy ions

Vickers hardness change of the Chinese low-activation ferritic/martensitic steel CLF-1 irradiated with high-energy heavy ions

Leveraging Deep Neural Networks for Estimating Vickers Hardness from Nanoindentation Hardness

Effect of cold work deformationon irradiation hardening of vanadium alloys

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