Article
Materials Science, Multidisciplinary
T. Sakthivel, C. R. Das, K. Laha, G. Sasikala
Summary: The boron containing modified 9Cr-1Mo steel (P91B-IC) exhibited higher creep rupture strength and lower minimum creep rate compared to the boron free modified 9Cr-1Mo steel (P91-IC) after intercritically heat-treated at 923K.
METALS AND MATERIALS INTERNATIONAL
(2021)
Article
Nanoscience & Nanotechnology
Yatindra Kumar, Manmath Kumar Dash, A. Moitra, G. Sasikala, Shaju K. Albert
Summary: This study quantifies the improvement in creep crack growth resistance in the heat-affected zone of boron-added modified 9Cr-1Mo steel welds at high temperatures. It demonstrates that the addition of boron can significantly reduce crack growth rates, decrease creep damage, and enhance resistance to creep crack growth.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Engineering, Multidisciplinary
J. Veerababu, Sunil Goyal, J. Vanaja, A. Nagesha, M. Vasudevan
Summary: The study on the creep-fatigue interaction behavior of modified 9Cr-1Mo steel reveals that the ASME code provides a more conservative design approach for this alloy.
INTERNATIONAL JOURNAL OF PRESSURE VESSELS AND PIPING
(2021)
Article
Materials Science, Multidisciplinary
Ping Fan, Xinbao Liu, Jinye Peng, Lin Zhu, Kai Zhang
Summary: This study investigated the creep damage of 9Cr-1Mo steel using nonlinear Lamb waves, and found that the measured acoustic nonlinearity parameter is strongly dependent on the creep state. The hierarchical microstructure of 9Cr-1Mo steel evolves during creep. By applying analytical models and kinetics of microstructure evolution, the predominant component of acoustic nonlinearity during the creep process was successfully identified.
MATERIALS CHARACTERIZATION
(2021)
Article
Chemistry, Physical
R. Rejeesh, Ankita Bhattacharya, Chandan Haldar, Rahul Mitra, Debalay Chakrabarti, C. R. Das, Shaju K. Albert, Arun Kumar Bhaduri
Summary: The systematic study on modified 9Cr-1Mo steel revealed the combined effect of B and N addition on microstructural stability and creep resistance. The best creep resistance was observed in the steel with 70 ppm B and 108 ppm N, while either too low B content or too high N content affected the precipitate stability and creep resistance of the steel.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Engineering, Multidisciplinary
Takashi Honda, Takuya Fukahori, Takumi Tokiyoshi, Yasuharu Chuman, Toshihide Igari, Alan C. F. Cocks
Summary: This paper discusses the prediction of residual life for Type IV creep failure in Ultra Super Critical (USC) plants by considering the increase of creep void density and the influence of stress state in welded joints with non-uniform weld metal materials, heat affected zone (HAZ) and base metal, compared to experimental results at 650 degrees C.
INTERNATIONAL JOURNAL OF PRESSURE VESSELS AND PIPING
(2021)
Article
Materials Science, Multidisciplinary
Prerna Mishra, R. S. Rajpurohit, N. C. Santhi Srinivas, G. V. S. Sastry, Vakil Singh
Summary: This study investigates the fatigue behavior and fracture characteristics of steel under asymmetric cyclic loading, finding that plastic strain increases with mean stress and stress amplitude, leading to reduced cyclic life. However, an increase in stress rate reduces accumulated plastic strain and increases cyclic life. Microstructural changes were observed with an increase in the three parameters, showing a transition from lath martensitic structure to subgrain structure, along with dislocation cells and forest dislocations. Scanning electron microscopy revealed unique features of fractured specimens, with progressive reduction in diameter towards the fracture-end, fatigue striations on the tapered circumferential surface and dimples on the fracture surface.
METALS AND MATERIALS INTERNATIONAL
(2021)
Article
Materials Science, Multidisciplinary
Prerna Mishra, N. C. Santhi Srinivas, Vakil Singh
Summary: This study compares the ratcheting fatigue life of modified 9Cr-1Mo steel and Inconel alloy 617 (IN-617) under the same stress conditions, and finds that uniform plastic strain plays a dominant role in the ratcheting fatigue resistance of materials. The accumulated plastic strain in IN-617 is significantly higher than that in modified steel, resulting in a longer ratcheting fatigue life. Therefore, uniform strain can be considered an important parameter for selecting materials for tubular products in power plants.
Article
Engineering, Multidisciplinary
Uijeong Ro, Sangyeop Kim, Yonghwi Kim, Moon Ki Kim
Summary: This study evaluates the lifespan of creep-fatigue interaction through finite element analyses, employing Voronoi tessellation method and damage models to describe creep and fatigue damaging mechanisms. New criteria for creep-fatigue life evaluation were proposed based on the results, which were between conventional standards.
INTERNATIONAL JOURNAL OF PRESSURE VESSELS AND PIPING
(2021)
Article
Engineering, Manufacturing
Tomotaka Hatakeyama, Kota Sawada, Masaru Suzuki, Makoto Watanabe
Summary: This study characterized the effect of laser powder bed fusion (LPBF) parameters on the microstructure development of modified 9Cr-1Mo steel and the relationship between the as-built and heat-treated microstructures using electron backscattered diffraction (EBSD). It was found that the optimal energy density for the steel was 100-150 J/mm3. The as-built steel exhibited a microstructure consisting mainly of coarse and columnar 8-ferrite grains and fine martensite grains. Higher energy density and a scan strategy with a 67-degree rotation in each layer were found to be suitable for obtaining a higher area fraction of martensite. Tempering reduced the hardness and enhanced the precipitation of M23C6 carbide at martensite, while maintaining the microstructural morphology in the as-built condition. The normalizing treatment affected the size of the prior austenite grains and eliminated the typical as-built microstructure.
ADDITIVE MANUFACTURING
(2023)
Article
Engineering, Mechanical
Sangyeop Kim, Uijeong Ro, Yong Hwi Kim, Taeksang Lee, Moon Ki Kim
Summary: This paper investigates creep damage in the pressure vessel of a very-high-temperature reactor and evaluates the creep properties of modified 9Cr-1Mo steel using the small punch creep test (SPCT). By converting the SPCT outputs into the strain and stress of conventional uniaxial creep tests (UCTs), the Norton, Larson-Miller, and Monkman-Grant creep models were successfully constructed and their triangular relationship was demonstrated. The validity of this study was verified by comparing it with long-term UCT results.
JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY
(2022)
Article
Materials Science, Multidisciplinary
Sumit Kumar, Anish Karmakar, Sumeer K. Nath
Summary: Hot forged 1Cr-1Mo and 9Cr-1Mo steels are increasingly used in turbine rotor manufacturing for steam power plants, requiring precise control of processing parameters for defect-free products. A comparative study analyzed the hot deformation behavior of both steels, determining flow stress behavior, activation energy, Zener-Hollomon parameter, and critical conditions for dynamic recrystallization. The study also focused on the comparison of dynamically recrystallized austenite volume fraction with respect to true strain. Microstructural evaluation and characterization were conducted to validate the kinetics of DRX and softening mechanism.
METALS AND MATERIALS INTERNATIONAL
(2021)
Article
Nanoscience & Nanotechnology
R. Rejeesh, Sankalp Biswal, Rahul Mitra, Debalay Chakrabarti, C. R. Das, Shaju K. Albert
Summary: Five different steels with varying boron (0-100 ppm) and nitrogen (20-500 ppm) concentrations were subjected to two types of weld thermal cycles, and the effects of boron and nitrogen on the heat affected zone creep resistance of modified 9Cr-1Mo steel were studied. High boron steels showed better creep resistance compared to low boron steels, and the effect of boron was found to be more significant than that of nitrogen. Additionally, the difference in rupture lives between simulated inter-critical HAZ and simulated coarse-grained HAZ specimens revealed the influence of triaxiality on rupture lives.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Materials Science, Multidisciplinary
Lizhen Tan, Weicheng Zhong, Ying Yang, Kevin G. Field, Niyanth Sridharan, Andrew T. Nelson
Summary: Limited studies have evaluated the creep behavior of additively manufactured ferritic-martensitic steels. This study investigated the creep behavior of a 9Cr FM steel fabricated by powder blown directed energy deposition technique. The results showed a threshold temperature between 600 and 625 degrees C, below which the steel exhibited better creep resistance compared to other steels. The creep behavior and fracture surface morphology also differed at temperatures above and below the threshold.
JOURNAL OF NUCLEAR MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
A. Venkata Krishna, A. K. Lakshminarayanan, P. Vasantharaja, M. Vasudevan
Summary: This article evaluates the indentation creep characteristics and microstructures of friction stir welded modified 9Cr-1Mo steel and LN-type 316 SS dissimilar joint. The microstructures of post-weld heat treated and indentation crept samples were characterized using various microscopy techniques. Different heat-affected zones were observed, with variations in thermal conductivity and transformation temperatures. The sizes of prior austenite grain sizes also varied significantly in different regions. Indentation creep data showed varying depths and steady-state creep behavior in different weld zones, which were correlated with the microstructures. The presence of small prior austenitic grain structures and grain boundary vacancies led to maximum creep deformation in the heat affected zone of the modified 9Cr-1Mo steel. The stir zone exhibited improved steady-state creep rate due to the presence of refined gamma and alpha ' layers. The LN-type 316 base metal showed resistance to creep damage and higher activation energy compared to the stir zone and heat affected zone.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART L-JOURNAL OF MATERIALS-DESIGN AND APPLICATIONS
(2023)
Article
Materials Science, Multidisciplinary
Liuming Wei, Jingwen Li, Yonggang Li, Qirong Zheng, Fan Cheng, Chuanguo Zhang, Jingyu Li, Gaofeng Zhao, Zhi Zeng
Summary: This study investigates the influence of He-V complexes on H behaviors on different W surfaces using DFT calculations. The results show that H dissolution is most difficult but H trapping is easiest on the W (110) surface, while the opposite is true on the W (111) surface. Moreover, the presence of He-V complexes increases the difficulty of H diffusion from bulk to surface and desorption.
JOURNAL OF NUCLEAR MATERIALS
(2024)
Article
Materials Science, Multidisciplinary
Yan Meng, Song Zeng, Chen Chen, Chaowen Zhu, Huahai Shen, Xiaosong Zhou, Xiaochun Han
Summary: The characteristics of magnetron sputtered Cr coatings vary with different temperature, bias voltage, and pressure. Coatings with random orientation, good crystallinity, and small grain size exhibit favorable oxidation behavior, while coatings with strong (200) texture, poor crystallinity, and large grains have many intrinsic defects that are detrimental to the protection property of the Cr coatings.
JOURNAL OF NUCLEAR MATERIALS
(2024)
Article
Materials Science, Multidisciplinary
Xinyuan Xu, Zefeng Yu, Wei-Ying Chen, Aiping Chen, Arthur Motta, Xing Wang
Summary: This study presents an automated approach for characterizing grain morphology in TEM images recorded during ion irradiation. By combining a machine learning model and a computer vision algorithm, comparable results to human analysis can be achieved with significantly reduced analysis time. Researchers can train their own models following the procedures described in this study to automate grain morphology analysis of their own TEM images.
JOURNAL OF NUCLEAR MATERIALS
(2024)
Article
Materials Science, Multidisciplinary
Shihao Wu, Dong Wang, Yapei Zhang, Koji Okamoto, Marco Pellegrini, Wenxi Tian, Suizheng Qiu, G. H. Su
Summary: The oxidation and degradation mechanisms of Cr coating on Zr alloy cladding under high temperature steam atmosphere are summarized, and a mathematical analysis model is established to predict the changes in coating thickness. The model is applied in the analysis of structure evolution under different conditions.
JOURNAL OF NUCLEAR MATERIALS
(2024)
Article
Materials Science, Multidisciplinary
V. Diaz-Mena, J. de Prado, M. Roldan, I. Izaguirre, M. Sanchez, M. Rieth, A. Urena
Summary: The brazeability of a cupronickel alloy was evaluated as a filler alloy for high-temperature joining of tungsten to steel. The study investigated the brazing conditions and the impact of the selected filler on the joint quality using numerical software. The results showed different metallurgical interactions and diffusion phenomena between the filler alloy and the base materials at different temperatures. The study emphasized the importance of selecting a suitable filler to mitigate residual stresses in the joints.
JOURNAL OF NUCLEAR MATERIALS
(2024)
Article
Materials Science, Multidisciplinary
Pengcheng Zhu, Yajie Zhao, Yan-Ru Lin, Jean Henry, Steven J. Zinkle
Summary: This study investigates the effect of heavy-ion irradiation on radiation hardening in high-purity binary alloy Fe18Cr. Nanoindentation testing and high-quality TEM imaging were conducted to extract hardness and microstructure information. The strength factor was accurately calculated based on the detailed TEM characterization of irradiated microstructures, and a refined hardening superposition method was applied to quantify the mechanical properties of ion-irradiated materials.
JOURNAL OF NUCLEAR MATERIALS
(2024)
Article
Materials Science, Multidisciplinary
Bin Wu, Haixia Ning, Hanzhen Zhu, Jianjun Chen, Kang Wang, Daiyu Zhang, Fu Wang, Qilong Liao
Summary: This study discusses the effects of ZrO2 and B2O3 on the phase composition and properties of SAP-based glass-ceramics. The results show that ZrO2 addition improves the formation of NZP phase while restricting the crystallization of AlPO4 phases. The correct ratios of ZrO2 and B2O3 allow only the formation of NZP phase within the SAP glass.
JOURNAL OF NUCLEAR MATERIALS
(2024)
Article
Materials Science, Multidisciplinary
Hwasung Yeom, Greg Johnson, Benjamin Maier, Tyler Dabney, Kumar Sridharan
Summary: Cr-Nb bilayer coatings were developed using cold spray deposition to improve the limiting operational temperature of Cr-coated Zr-alloy system. The coatings exhibited outstanding oxidation resistance at high temperatures and formed continuous intermetallic compound layers at the interfaces.
JOURNAL OF NUCLEAR MATERIALS
(2024)
Article
Materials Science, Multidisciplinary
Padhraic L. Mulligan, Andrew T. Nelson, Chad M. Parish, Patrick A. Champlin, Xiang Chen, Daniel Morrall, Jason M. Harp
Summary: Environmental barrier coatings are being developed to reduce oxidation and embrittlement in Zr-based materials. Chromium nitride is a candidate for this application, but understanding its impact on irradiation-induced creep and microstructure is critical.
JOURNAL OF NUCLEAR MATERIALS
(2024)
Article
Materials Science, Multidisciplinary
Dexuan Yan, Xinlei Cao, Ke Shen
Summary: This study investigated the purification mechanism of polycrystalline graphite by comparing IG-11 graphite with IG-110 nuclear grade graphite. The analysis revealed that metallic impurities in IG-11 were primarily segregated within graphite porosities, while IG-110 demonstrated a significant reduction in impurities. This research contributes to the development of innovative graphite purification techniques for greater purity and stronger oxidation resistance.
JOURNAL OF NUCLEAR MATERIALS
(2024)
Article
Materials Science, Multidisciplinary
Wei Xu, Wei Peng, Lei Shi, Qi Sun
Summary: This paper investigates the oxidation and shape evolution of matrix graphite in high temperature gas-cooled reactors during air-ingress accidents. A reaction kinetics model is established and computational fluid dynamics with a dynamic mesh method is used to simulate the oxidation process. The results show that the geometric shape of graphite changes significantly with increasing flow rate, and the graphite pebbles tend to form a structure with a narrow front and wide tail.
JOURNAL OF NUCLEAR MATERIALS
(2024)
Article
Materials Science, Multidisciplinary
Allison Harward, Casey Elliott, Michael Shaltry, Krista Carlson, Tae-Sic Yoo, Guy Fredrickson, Michael Patterson, Michael F. Simpson
Summary: This paper investigates the hygroscopic properties of eutectic LiCl-KCl absorbed into zeolite-4A. The study finds that water absorption and corrosion worsen with increasing salt loading. It also suggests that the salt can be stored in a non-inert atmosphere for a certain period of time.
JOURNAL OF NUCLEAR MATERIALS
(2024)
Article
Materials Science, Multidisciplinary
Takaaki Koyanagi, Xunxiang Hu, Christian M. Petrie, Gyanender Singh, Caen Ang, Christian P. Deck, Weon-Ju Kim, Daejong Kim, James Braun, Yutai Katoh
Summary: This study provides critical experimental data on the effects of irradiation on the hermeticity of SiC composite cladding, finding that irradiation can cause a decrease in hermeticity and cracking, and coating the outer surface can mitigate the cracking issue.
JOURNAL OF NUCLEAR MATERIALS
(2024)
Article
Materials Science, Multidisciplinary
S. Krat, A. Prishvitsyn, Yu. Gasparyan
Summary: This study proposes a probabilistic and diffusion-based model to describe the co-deposition of multiple hydrogen isotopes with slowly grown metal layers. The model calculates the relative concentrations of different hydrogen isotopes in the co-deposited metal layers. It is found that if hydrogen isotopes have different detrapping energies, only the isotope with the highest detrapping energy shows a monotonic decrease in concentration with deposition temperature. Furthermore, the study evaluates the uncertainty of tritium concentration in the co-deposited layer based on the uncertainty in detrapping energy of tritium and deuterium, predicting a >10% tritium concentration uncertainty for a 0.01 eV difference.
JOURNAL OF NUCLEAR MATERIALS
(2024)
Article
Materials Science, Multidisciplinary
Tijo Vazhappilly, Arup Kumar Pathak
Summary: This study investigates the effect of Ce atom substitution in UO2 on its thermophysical properties using density functional theory. The results show that the Ce substitution levels and the oxidation state of Ce/U atoms strongly influence the band structure and specific heat capacity of the UO2 lattice. These findings provide important insights into the fuel properties of UO2 under reactor conditions.
JOURNAL OF NUCLEAR MATERIALS
(2024)