Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Microstructure of Zircaloy-4 alloy during β phase quenching and determination of critical quenching diameter of its rods
The corrosion resistance of zirconium alloys is closely related to the size of precipitates. β-phase quenching is the key process for controlling the precipitate size of zirconium alloy. In this study, the microstructure and the precipitates size of nuclear graded Zircaloy-4 (hereinafter called as Zr-4) alloy treated by the quenching in different cooling mediums were studied, and the critical quenching diameter of the Zr-4 alloy rod was determined by finite element method. The results showed that, the cooling rate of the β-phase quenching had small effect on the grain size of the alloy, however the size of the needle α grains increased with a decrease of cooling rate. The thickness of α grains quenched in water, quenched in oil, quenched at room temperature and quenched at 440 °C were about 1 μm, 5 μm, 9 μm, and 15 μm, respectively. When the cooling rate was high (water-quenching and oil-quenching), the precipitates formed only along the grain boundary, and with the length of less than 100 nm. When the cooling rate was low (air quenching), precipitates formed not only at the grain boundaries but also inside the grains, and the precipitates length was about 150–200 nm. When the Zr-4 alloy rod was quenched in water or oil, the maximum diameter of the specimen with suitable precipitate size (about 100–200 nm) was 140 and 97 mm, respectively. Keywords: Zr-4 alloy, βphase quenching, Cooling rate, Microstructure, Critical quenching diameter
Microstructure of Zircaloy-4 alloy during β phase quenching and determination of critical quenching diameter of its rods
The corrosion resistance of zirconium alloys is closely related to the size of precipitates. β-phase quenching is the key process for controlling the precipitate size of zirconium alloy. In this study, the microstructure and the precipitates size of nuclear graded Zircaloy-4 (hereinafter called as Zr-4) alloy treated by the quenching in different cooling mediums were studied, and the critical quenching diameter of the Zr-4 alloy rod was determined by finite element method. The results showed that, the cooling rate of the β-phase quenching had small effect on the grain size of the alloy, however the size of the needle α grains increased with a decrease of cooling rate. The thickness of α grains quenched in water, quenched in oil, quenched at room temperature and quenched at 440 °C were about 1 μm, 5 μm, 9 μm, and 15 μm, respectively. When the cooling rate was high (water-quenching and oil-quenching), the precipitates formed only along the grain boundary, and with the length of less than 100 nm. When the cooling rate was low (air quenching), precipitates formed not only at the grain boundaries but also inside the grains, and the precipitates length was about 150–200 nm. When the Zr-4 alloy rod was quenched in water or oil, the maximum diameter of the specimen with suitable precipitate size (about 100–200 nm) was 140 and 97 mm, respectively. Keywords: Zr-4 alloy, βphase quenching, Cooling rate, Microstructure, Critical quenching diameter
Microstructure of Zircaloy-4 alloy during β phase quenching and determination of critical quenching diameter of its rods
Jia Ni (Autor:in) / Yicheng Zhao (Autor:in) / Lian Wang (Autor:in) / Zhihao Zhang (Autor:in) / Jianxin Xie (Autor:in)
2018
Aufsatz (Zeitschrift)
Elektronische Ressource
Unbekannt
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