Effect of Heat Treatment on the Creep Properties of Zr-1Nb-0.12O Nuclear Cladding Tubes

Creep properties of one-step and two-step annealed Zr-1Nb-0.12O cladding tubes were studied. Creep tests were carried out at 450~500 °C with the applied stress between 80MPa and 120MPa The creep rates of the two-step annealed Zr-1Nb-0.12O alloy were found to be slower than those of the one-step annealed Zr-1Nb-0.12O alloy. The creep rate decreased with increase of grain size with annealing for Zr-1Nb-0.12O at intermediate temperatures, suggesting the creep resistance can be enhanced by the grain size control. The creep life of two-step annealed Zr-1Nb-0.12O increased over the one-step annealed Zr-1Nb-0.12O by the factor of 18~20 despite the greater initial instantaneous strain.

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Creep Behaviors of Stress-Relieved and Annealed Zr-1Nb-0.7Sn-0.1Fe Nuclear Cladding Tubes at Intermediate Temperatures

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.248.343 ◽

2012 ◽

Vol 248 ◽

pp. 343-348

Author(s):

Jong Min Lee ◽

Sun Ig Hong

Keyword(s):

Grain Size ◽

Creep Rate ◽

Stress Exponent ◽

Creep Resistance ◽

Size Control ◽

Dislocation Climb ◽

Creep Life ◽

Creep Tests ◽

Grain Size Control ◽

Zr Alloys

In order to explore the possibility of enhanced creep resistance by grain size control, creep tests of stress-relieved and annealed Zr-1Nb-0.7Sn-0.1Fe cladding tubes were carried out at intermediate temperatures. The creep rate decreased significantly with increase of grain size from ~1.2 μm to 4 μm with annealing. The stress exponent was observed to be in the range of 5.0~6.5 for both stress-relieved and annealed Zr-1Nb-0.7Sn- 0.1Fe, suggesting that the dislocation climb is the rate controlling creep mechanism. It was shown that not only the creep rate decreased but also creep life increased in the annealed Zr-1Nb-0.7Sn-0.1Fe, suggesting the grain size control may provide an effective way to enhance the creep resistance in Zr alloys for nuclear application.

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Effect of Aging Heat Treatment Conditions on the Mechanical Properties and Microstructure of Base and Weld Metal of Alloy 282 Superalloy

Korean Journal of Metals and Materials ◽

10.3365/kjmm.2020.58.8.540 ◽

2020 ◽

Vol 58 (8) ◽

pp. 540-549

Author(s):

Jinhyeok Bang ◽

Yongjoon Kang ◽

Namkyu Kim ◽

Seong-Moon Seo ◽

Sanghoon Lee ◽

...

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Weld Metal ◽

Base Metal ◽

Aged Condition ◽

Creep Life ◽

Aging Heat Treatment ◽

Treatment Conditions ◽

One Step ◽

The One

The effect of aging heat treatment conditions on the mechanical properties and microstructure of the base and weld metal of Alloy 282 superalloy was investigated. The aging heat treatment conditions employed in this study were as follows: two-steps (1010 °C for 2 hours plus 788 °C for 8 hours) and one-step at 788 °C, 738 °C, and 688 °C for 4 hours. The base metal with the one-step aged condition exhibited lower hardness but longer creep life than that treated with the two-step aged condition. The base metal subjected to the two-step aging exhibited the highest hardness and the shortest creep life, mainly due to the precipitation of Mo-rich M6C-type carbides and coarse <i>γ</i>' (Ni3(Al,Ti)) phase. For the weld metal, regardless of aging heat treatment conditions, creep elongation and life decreased significantly compared to the base metal, due to the coarse effective grain size and inhomogeneous distribution of <i>γ</i>' precipitates.

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Effect of heat treatment on the grain size control, superplasticity, internal friction, and mechanical properties of zirconium-bearing aluminum-based alloy

Journal of Alloys and Compounds ◽

10.1016/j.jallcom.2020.157455 ◽

2020 ◽

pp. 157455

Author(s):

A.G. Mochugovskiy ◽

A.V. Mikhaylovskaya ◽

M. Yu Zadorognyy ◽

I.S. Golovin

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Grain Size ◽

Internal Friction ◽

Size Control ◽

Grain Size Control

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Interfacial studies in Nb3Sn superconductors

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100087264 ◽

1991 ◽

Vol 49 ◽

pp. 590-591

Author(s):

Ernest L. Hall ◽

Lee E. Rumaner ◽

Mark G. Benz

Keyword(s):

Grain Size ◽

Grain Boundaries ◽

Flux Pinning ◽

Size Control ◽

High Magnetic Fields ◽

Type Ii ◽

Reaction Interface ◽

Liquid Diffusion ◽

Type Ii Superconductor ◽

Grain Size Control

The intermetallic compound Nb3Sn is a type-II superconductor of interest because it has high values of critical current density Jc in high magnetic fields. One method of forming this compound involves diffusion of Sn into Nb foil containing small amounts of Zr and O. In order to maintain high values of Jc, it is important to keep the grain size in the Nb3Sn as small as possible, since the grain boundaries act as flux-pinning sites. It has been known for many years that Zr and O were essential to grain size control in this process. In previous work, we have shown that (a) the Sn is transported to the Nb3Sn/Nb interface by liquid diffusion along grain boundaries; (b) the Zr and O form small ZrO2 particles in the Nb3Sn grains; and (c) many very small Nb3Sn grains nucleate from a single Nb grain at the reaction interface. In this paper we report the results of detailed studies of the Nb3Sn/Nb3Sn, Nb3Sn/Nb, and Nb3Sn/ZrO2 interfaces.

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Grain Size Evolution and Mechanical Properties of Nb, V–Nb, and Ti–Nb Boron Type S1100QL Steels

Metals ◽

10.3390/met11030492 ◽

2021 ◽

Vol 11 (3) ◽

pp. 492

Author(s):

Jan Foder ◽

Jaka Burja ◽

Grega Klančnik

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Grain Size ◽

Hot Forging ◽

Size Control ◽

High Strength ◽

Fatigue Properties ◽

Titanium Addition ◽

Austenite Grain Size ◽

Size Evolution

Titanium additions are often used for boron factor and primary austenite grain size control in boron high- and ultra-high-strength alloys. Due to the risk of formation of coarse TiN during solidification the addition of titanium is limited in respect to nitrogen. The risk of coarse nitrides working as non-metallic inclusions formed in the last solidification front can degrade fatigue properties and weldability of the final product. In the presented study three microalloying systems with minor additions were tested, two without any titanium addition, to evaluate grain size evolution and mechanical properties with pre-defined as-cast, hot forging, hot rolling, and off-line heat-treatment strategy to meet demands for S1100QL steel. Microstructure evolution from hot-forged to final martensitic microstructure was observed, continuous cooling transformation diagrams of non-deformed austenite were constructed for off-line heat treatment, and the mechanical properties of Nb and V–Nb were compared to Ti–Nb microalloying system with a limited titanium addition. Using the parameters in the laboratory environment all three micro-alloying systems can provide needed mechanical properties, especially the Ti–Nb system can be successfully replaced with V–Nb having the highest response in tensile properties and still obtaining satisfying toughness of 27 J at –40 °C using Charpy V-notch samples.

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