Long Term, In Situ Material Degradation Studies Utilizing High Resolution Laboratory X-ray Tomography

利用高分辨率实验室 X 射线断层扫描进行长期原位材料降解研究

• 批准号: EP/H025286/1
• 负责人: Brian Connolly
• 金额: $ 12.87万
• 依托单位: University of Birmingham
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2010
• 资助国家: 英国
• 起止时间: 2010 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FH025286%2F1
• 关键词: Long; Term; Situ; Material; Degradation

Although recent years have seen rapid growth in the use of X-ray tomography to non-destructively observe and quantify microstructure and defects within the bulk of materials, the availability of long term 4D (time and spatial resolution) characterisation remains limited especially where specific environmental conditions are needed in degradation studies. While synchrotron facilities provide state-of-the-art capability in terms of high resolution, in situ observations with high speed acquisition, allocation of beam time to individual users (in some cases a maximum of 3-4 days per annum) limits the opportunities to study the evolution of defects in real systems. There exists a general need for laboratory x-ray facilities for long term experiments that do not need the advanced capabilities available at a synchrotron light sources. The proposed research strives to establish research capability within the UK, in collaboration with the Henry Moseley X-ray Imaging Facility at the University of Manchester, to provide for long term in situ characterisation of environmental degradation under static and dynamic load. The project builds on our recent work which has demonstrated effective capability of in situ measurements at synchrotron facilities in characterising and quantifying the evolution of localised corrosion and stress corrosion cracking events. Validation of the capability of the environmental stressing stage will be conducted via the extension of an on-going programme to address current critical issue in environmental degradation of turbine disc steels in a simulated condensed steam environment under static and dynamic loading. Steam turbines are a particular industrial example where pitting and stress corrosion cracking impinge directly on structural integrity. Maintaining availability of operating plant has become strategically important in response to the increasing demand for a reliable energy supply. It is imperative to obtain relevant data and to develop a predictive framework combined with an understanding of damage mechanisms to enable informed decisions concerning life extension of existing plant and life assessment of next generation plant. Previous studies by this group via ex situ microCT experiments indicate cracks evolve from pits in this system over a timescale of 500 to 5000 hours. The evidence provided by the x-ray tomographic analysis necessitates a re-assessment of quantitative modelling of the early stages of stress corrosion crack growth from pits and suggests a complexity that may be intractable on a deterministic basis. A reliance on empirical assessment for engineering application would seem inevitable and there is need for further investigation into the specific character of early stages of crack initiation, coalescence and propagation during the entire life of specific pit-to-crack events. This information cannot be easily obtained via ex situ tomographic experiments and, therefore, in situ capability is necessary to provide more robust life prediction strategies. It should be emphasised that the modelling criteria were focused on fatigue cracks and its use in that context is not specifically questioned by the ex situ x-ray tomography analysis for stress corrosion cracking in this system. More detailed exploration of the early stages of corrosion fatigue crack evolution from corrosion pits would be informative for this system as well and will be performed during the advanced stages of the programme.

尽管近年来使用 X 射线断层扫描来非破坏性观察和量化大量材料内的微观结构和缺陷的情况迅速增长，但长期 4D（时间和空间分辨率）表征的可用性仍然有限，特别是在降解研究中需要特定环境条件的情况下。虽然同步加速器设施在高分辨率方面提供了最先进的能力，但通过高速采集进行原位观测，向个人用户分配光束时间（在某些情况下每年最多 3-4 天）限制了研究实际系统中缺陷演变的机会。对于不需要同步加速器光源的先进功能的长期实验，普遍需要实验室 X 射线设施。拟议的研究致力于与曼彻斯特大学亨利·莫斯利 X 射线成像设施合作，在英国建立研究能力，以提供静态和动态载荷下环境退化的长期原位表征。该项目建立在我们最近的工作基础上，该工作证明了同步加速器设施的原位测量在表征和量化局部腐蚀和应力腐蚀开裂事件的演变方面的有效能力。将通过扩展正在进行的计划来验证环境应力阶段的能力，以解决静态和动态负载下模拟凝结蒸汽环境中涡轮盘钢环境退化的当前关键问题。汽轮机是一个特殊的工业例子，点蚀和应力腐蚀开裂直接影响结构完整性。为了满足对可靠能源供应日益增长的需求，保持运行工厂的可用性已变得具有重要的战略意义。必须获取相关数据并开发一个预测框架，并结合对损坏机制的了解，以便就现有核电站的寿命延长和下一代核电站的寿命评估做出明智的决策。该小组之前通过异位显微 CT 实验进行的研究表明，在 500 至 5000 小时的时间尺度内，该系统中的凹坑会产生裂纹。 X 射线断层扫描分析提供的证据需要重新评估凹坑应力腐蚀裂纹扩展早期阶段的定量模型，并表明其复杂性在确定性基础上可能难以处理。工程应用中对经验评估的依赖似乎是不可避免的，并且需要进一步研究特定坑到裂纹事件的整个生命周期中裂纹萌生、合并和扩展的早期阶段的具体特征。这些信息无法通过异位断层扫描实验轻松获得，因此，需要原位能力来提供更稳健的寿命预测策略。应该强调的是，建模标准主要关注疲劳裂纹，并且该系统中应力腐蚀裂纹的异位 X 射线断层扫描分析并未具体质疑其在该背景下的使用。对腐蚀坑腐蚀疲劳裂纹演变的早期阶段进行更详细的探索也将为该系统提供信息，并将在该计划的后期阶段进行。

项目成果

Novel images of the evolution of stress corrosion cracks from corrosion pits

• DOI: 10.1016/j.corsci.2011.05.050
• 发表时间: 2011-11-01
• 期刊: CORROSION SCIENCE
• 影响因子: 8.3
• 作者: Horner, D. A.;Connolly, B. J.;Turnbull, A.
• 通讯作者: Turnbull, A.

In situ measurement of the strains within a mechanically loaded polygranular graphite

• DOI: 10.1016/j.carbon.2015.09.058
• 发表时间: 2016
• 期刊: Carbon
• 影响因子: 10.9
• 作者: T. Marrow;Dong Liu;S. Barhli;L. S. Mora;Yelena Vertyagina;D. Collins;C. Reinhard;S. Kabra

Synchrotron X-ray characterization of crack strain fields in polygranular graphite

• DOI: 10.1016/j.carbon.2017.08.075
• 发表时间: 2017-11-01
• 期刊: CARBON
• 影响因子: 10.9
• 作者: Barhli, S. M.;Saucedo-Mora, L.;Marrow, T. J.
• 通讯作者: Marrow, T. J.

Observation and simulation of indentation damage in a SiC-SiCfibre ceramic matrix composite

• DOI: 10.1016/j.finel.2015.11.003
• 发表时间: 2016-03
• 期刊: Finite Elements in Analysis and Design
• 影响因子: 3.1
• 作者: L. Saucedo-Mora;M. Mostafavi;D. Khoshkhou;C. Reinhard;R. Atwood;Shuangxi Zhao;B. Connolly;T. Marrow