Understanding of the stress assisted cracking behavior of Ni-based alloy GH3535 in molten LiF-NaF-KF salt

IF 7.4 1区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Corrosion Science Pub Date : 2025-05-16 DOI:10.1016/j.corsci.2025.113038

Wenjun Liang , Xiaoli Li , Yumiao Wang , Bin Leng , Tao Wu , Litao Chang

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Abstract

Environmentally assisted cracking of structural materials is an important concern to the safe operation of advanced nuclear reactors. In the present study, the responses of Ni-based alloy GH3535 to the combined effects of tensile stress and molten fluoride salt corrosion was investigated using constant load tensile testing alongside with specimens tested in Ar. The results indicated that extensive intergranular cracking occurred in specimens tested in both environments, however, specimens tested in the molten salt had a much faster displacement/creep rate than those tested in Ar. All the cracks were internally initiated within the sub-surface region of the specimens, with no cracking observed in the substrate. For specimens tested in Ar, most of the cracks were found to be beneath the surface, whereas the cracks propagated to the surface and penetrated deeper to the substrate for specimens tested in the molten salt. All the cracks were confirmed to be creep cracks, and it was found that initiation of the internal creep cracks was promoted by the deformation induced by the surface machining process. Furthermore, increased creep rates for specimens tested in molten salt was due to stress concentration at the crack tips, caused by the fracture of the interconnected, topmost recrystallized fine-grained layer.

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ni基合金GH3535在LiF-NaF-KF熔盐中的应力辅助开裂行为

结构材料的环境辅助开裂是先进核反应堆安全运行的一个重要问题。在本研究中，通过恒载拉伸试验和氩气中测试的试样，研究了ni基合金GH3535对拉应力和熔氟盐腐蚀联合作用的响应。结果表明，在两种环境下测试的试样都发生了广泛的晶间开裂。在熔盐中测试的试样的位移/蠕变速率比在氩气中测试的试样要快得多。所有的裂纹都是在试样的亚表面区域内部开始的，在基体中没有观察到裂纹。对于在氩气中测试的试样，发现大多数裂纹位于表面以下，而在熔盐中测试的试样，裂纹扩展到表面并深入到基材。所有裂纹均为蠕变裂纹，并发现表面加工过程引起的变形促进了内部蠕变裂纹的萌生。此外，在熔盐中测试的试样蠕变速率的增加是由于裂纹尖端的应力集中，这是由互连的，最上面的再结晶细粒层的断裂引起的。

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来源期刊

Corrosion Science 工程技术-材料科学：综合

CiteScore

13.60

自引率

18.10%

发文量

763

审稿时长

46 days

期刊介绍： Corrosion occurrence and its practical control encompass a vast array of scientific knowledge. Corrosion Science endeavors to serve as the conduit for the exchange of ideas, developments, and research across all facets of this field, encompassing both metallic and non-metallic corrosion. The scope of this international journal is broad and inclusive. Published papers span from highly theoretical inquiries to essentially practical applications, covering diverse areas such as high-temperature oxidation, passivity, anodic oxidation, biochemical corrosion, stress corrosion cracking, and corrosion control mechanisms and methodologies. This journal publishes original papers and critical reviews across the spectrum of pure and applied corrosion, material degradation, and surface science and engineering. It serves as a crucial link connecting metallurgists, materials scientists, and researchers investigating corrosion and degradation phenomena. Join us in advancing knowledge and understanding in the vital field of corrosion science.