Evaluation of Workability on Microstructure and Mechanical Property of Modified 9Cr-2W Steel for Fuel Cladding by Cold Drawing Process and Intermediate Heat Treatment Condition

hyeongmin, Heo; Kim, Jun-Hwhan; Kim, Sung Hoon; Kim, Jongryoul

doi:10.20944/preprints201801.0056.v1

Cited by 3 publications

(1 citation statement)

References 15 publications

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“…Validity of the compression test as a general method of evaluating cold workability is investigated [15][16][17]. Compression test was performed at room temperature and strain rate of 1mm/min using an INSTRON-3367 to evaluate the mechanical properties and workability of the Alloy B and Gr.92 under the specific heat treatment conditions.…”

Section: Compression Testmentioning

confidence: 99%

Influence of Heat Treatment on the Workability of Modified 9Cr-2W Steel with Higher B Content

Heo¹,

Kim²,

Kim³

et al. 2019

Preprint

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In this study, the effect of heat treatment was investigated to influence the occurrence of fracture during manufacturing process of Alloy B steel with boron contents as high as 130 ppm. As the content of boron increases, it affects the phase transformation temperature and texture. The development of {111} components in the γ-fiber is affected depending on the austenite fraction after phase transformation. The Alloy B steel indicated that the increase in the boron content increased the α to γ phase transformation temperature such that sufficient transformation did not occur in the normalizing condition. The cracks occurred at the point of the transition from elastic to plastic deformation in the ND direction during the rolling process, thereby resulting in failure.Therefore, it is necessary to avoid the intermediate heat treatment condition in which γ-fiber does not fully develop, i.e., an imperfect normalization. IntroductionNuclear power generation plays a key role in the Korea energy with low costs of raw materials and excellent base load capacity, however its enlargement is limited due to problem of spent nuclear fuel after operation. To solve these problems, it is necessary to develop an innovative nuclear power plant which can contribute to sustainable development, environmental protection and preparation for rapidly increasing energy consumption [1,2].Recently, research has carried out to develop sodium cooled fast reactor (SFR) because it has many advantages in terms of economic efficiency, stability, nuclear non-proliferation and reducing the emission of spent nuclear fuel. It is designed to operate at temperature much higher than those in light water reactors and to improve thermal efficiency [3][4][5][6][7]. Nuclear fuel cladding tube which transfers efficient the fission energy and confines nuclear fuel rod and fissile material is a main component. Hence, the development of fuel cladding tube is essential as it is the most important component directly related to the safety of nuclear reactor.Ferritic-martensitic (FM) steels have been considered as fuel cladding and duct materials for a SFR owing to their high thermal conductivities, low expansion coefficients and superior irradiation swelling compared to austenitic steel [8][9][10]. However, the creep rupture strength of FM steels abruptly decreases during long term creep exposure at high temperature [11]. An advanced FM steel alloy was developed on the basis of Gr.92 steel. Minor alloying elements such as B, N, Nb, Ta, and C Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 16

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Section: Compression Testmentioning

confidence: 99%

Influence of Heat Treatment on the Workability of Modified 9Cr-2W Steel with Higher B Content

Heo¹,

Kim²,

Kim³

et al. 2019

Preprint

Self Cite

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Effects of Tempering Temperature on the Microstructure and Mechanical Properties of T92 Heat-Resistant Steel

Zhao

Zhang

et al. 2019

Metals

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T92 heat-resistant steel is among the most promising candidate materials for structural components in the Generation IV (GEN-IV) reactors. The effects of tempering temperature on the microstructure and mechanical properties of the T92 steel were studied. The microstructural evolution of the T92 steel subjected to various temperatures of the tempering process were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and synchrotron radiation X-ray diffraction (SR-XRD). The mechanical properties of Vickers hardness, tensile test, and impact test were also investigated. The results showed that the grain size of the prior austenite does not significantly change during the tempering process, while the width of the martensite lath and the size of the carbide precipitates increased with increasing tempering temperature. The hardness and yield strength of the T92 steel decreased, and the plasticity and impact energy increased with increasing tempering temperature. Coarsening of the carbide precipitates during the tempering process was considered to be the dominant factor that reduced the yield strength in the T92 steel.

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Influence of Heat Treatment on the Workability of Modified 9Cr-2W Steel with Higher B Content

Heo

Kim

et al. 2019

Metals

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In this study, the effect of heat treatment on the fracture behavior of alloy B steel with boron (B) contents as high as 130 ppm was investigated. The Alloy B are derived from Gr.92 steel with outstanding creep characteristics. The amounts of minor alloying elements such as B, N, Nb, Ta, and C were optimized to achieve better mechanical properties at high temperatures. Hence, workability of the alloy B and Gr.92 were compared. An increase in the B content affected the phase transformation temperature and texture of the steel. The development of the {111}<uvw> components in γ-fibers depended on the austenite fraction of the steel after the phase transformation. An increase in the B content of the steel increased its α-to-γ phase transformation temperature, thus preventing the occurrence of sufficient transformation under the normalizing condition. Cracks occurred at the point of the elastic-to-plastic deformation transition in the normal direction during the rolling process, thereby resulting in failure. Therefore, it is necessary to avoid intermediate heat treatment conditions, in which γ-fibers do not fully develop, i.e., to avoid an imperfect normalization.

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Evaluation of Workability on Microstructure and Mechanical Property of Modified 9Cr-2W Steel for Fuel Cladding by Cold Drawing Process and Intermediate Heat Treatment Condition

Abstract: Abstract:In this study, we evaluated the cold drawing workability of two kinds of modified 9Cr- 132W steel containing different contents of boron and nitrogen, depending on the temperature and time

Cited by 3 publications

References 15 publications

Influence of Heat Treatment on the Workability of Modified 9Cr-2W Steel with Higher B Content

Influence of Heat Treatment on the Workability of Modified 9Cr-2W Steel with Higher B Content

Effects of Tempering Temperature on the Microstructure and Mechanical Properties of T92 Heat-Resistant Steel

Influence of Heat Treatment on the Workability of Modified 9Cr-2W Steel with Higher B Content

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