New Correlative Microscopy Approaches to Understand the Microstructural Origins of Creep Cavitation in Austenitic Steels
New Correlative Microscopy Approaches to Understand the Microstructural Origins of Creep Cavitation in Austenitic Steels
复制标题
了解奥氏体钢蠕变空化微观结构起源的新相关显微镜方法
DOI：
10.1017/s1431927622008030
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发表时间：
2022
影响因子：
2.8
通讯作者：
Martin T
中科院分区：
文献类型：
--
作者：
Martin T
蠕变是航空航天和核反应堆等工业中高温、高应力环境下的重要退化机制。金属部件在较长的时间段内逐渐积累蠕变损伤，最终可能形成裂纹。理解失效部件中这些过程背后的微观结构机制或使用基于实验室的单轴蠕变试验是复杂的，因为在断裂前的最后阶段发生的大的延性变形会掩盖导致断裂的许多微妙特征。通常，中断试验提供了更好的空化早期阶段的代表性数据，但这对理解纳米尺度的空腔如何在更大的长度尺度上分布提出了挑战[1]。通常只有通过结合不同长度尺度的多种表征技术才能充分表征蠕变损伤的全貌[2]。在这项研究中，我们将探索新的方法来了解用于先进气冷核反应堆（AGR）的AISI 316 H奥氏体不锈钢中蠕变空穴的形成，通过锅炉集管的退役材料和实验室单轴蠕变试样。我们提出了新的相关显微镜的方法来了解早期阶段的成核蠕变腔失败之前，使用扫描电子显微镜（SEM），电子背散射衍射（EBSD），聚焦离子束（FIB）成像辅助二氟化氙（XeF2）气体和透射电子显微镜（TEM）的组合，连同机器学习辅助图像识别处理。
Creep is an important degradation mechanism in high temperature, high stress environments in industries such as aerospace and nuclear reactors. Metallic components gradually accumulate creep damage over extended periods of time that can eventually build to cracking. Understanding the microstructural mechanisms behind such processes in failed components or using laboratory-based uniaxial creep tests is complicated by the large ductile deformation that occurs in the final period prior to fracture, which can obscure many of the subtler features that caused it. Typically an interrupted test gives better representative data of the early stages of cavitation, but this presents challenges to understand how nanometer-scale cavities are distributed at larger length scales [1]. Often only by combining multiple characterization techniques across different length scales can the full picture of creep damage be fully characterized [2].In this study we will explore new ways to understand how creep cavitation forms in AISI 316H austenitic stainless steel used for advanced gas-cooled nuclear reactors (AGRs), through both ex-service material from a boiler header and laboratory uniaxial creep test specimens. We present new correlative microscopy approaches to understand the early stage nucleation of creep cavities prior to failure using a combination of scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), focused ion beam (FIB) imaging assisted by xenon difluoride (XeF2) gas and transmission electron microscopy (TEM), together with machine-learning assisted image recognition processing.