Effect of alloy elements and hydride morphology on hydrogen embrittlement of zirconium alloy = 합금원소와 수소화물 형상이 지르코늄 합금의 수소 취성에 미치는 영향

The effects of Nb and Sn on hydride embrittlement of Zr alloys were investigated. For this, experimental Zr alloys were prepared in a sheet shape and charged with hydrogen. The microstructure and hydride morphology were analyzed and the tensile properties were measured to understand the role of Nb and Sn on the hydride embrittlement of Zr alloy. With addition of Nb and Sn, recrystallization was retarded during the final annealing heat treatment. The retardation was mainly caused from $\beta-Nb$ precipitates and Sn solute atoms, which was confirmed from texture analyses. Of the two, Sn was found to more effective in retarding recrystallization. When hydrogen was charged, hydride clusters with stacked hydride platelets were observed in unalloyed Zr. However, with addition of Nb and Sn, such hydride clusters were replaced with hydrides platelets which were more or less aligned with the rolling direction and linked up on the rolling plane, and hydride length and the spacing between hydrides were increased. This change in hydride morphology was caused by the retardation of recrystallization. Again, Sn was found to be more effective in in modifying the hydride morphology and aligning hydrides on the rolling plane. Both Nb and Sn contributed to the strengthening of Zr alloys, but Sn is more effective in strengthening than Nb. However, tensile strengths of the experimental alloys were nearly independent of the absorbed hydrogen contents. While ductility was reduced with increasing hydrogen contents, the degree of ductility loss was dependent on Nb and Sn contents which increased hydrogen solubility and retarded recrystallization. For alloys with 1%-Nb and/or 1%-Sn, increase in hydrogen solubility was the main contributor to increase in resistance to hydride embrittlement. On the other hand, for an alloy with 2%-Nb resulted in large amount of $\beta$ -Nb precipitates, which in turn significantly retarded recrystallization. Therefore, the added contribution of r...
Advisors
Jang, Chang-Heuiresearcher장창희researcher
Publisher
한국과학기술원
Issue Date
2009
Identifier
309300/325007  / 020025183
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 원자력및양자공학과, 2009.2, [ ix, 109 p. ]

Keywords

Zirconium; Niobium; Tin; hydrogen; hydrogen embrittlement; 지르코늄; 나이오븀; 주석; 수소; 수소취성

URI
http://hdl.handle.net/10203/48766
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=309300&flag=t
Appears in Collection
NE-Theses_Ph.D.(박사논문)
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