Corrosion pitting and environmentally assisted small crack growth
Corrosion pitting and environmentally assisted small crack growth
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DOI：
10.1098/rspa.2014.0254
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发表时间：
2014-09
期刊：
影响因子：
--
通讯作者：
A. Turnbull
中科院分区：
文献类型：
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作者：
A. Turnbull
在许多应用中，腐蚀坑是开裂的先兆，但由于缺乏对腐蚀坑形成裂纹的过程的了解，对损伤演变的定性和定量预测一直受到阻碍。概述了利用先进的三维成像技术，如x射线计算机断层扫描和扫描电子显微镜聚焦离子束加工，在表征和理解坑到裂纹转变方面的最新突破。在有限元分析的支持下，这些技术提供了关于裂缝发展位置的新见解。这启发了一个关于点蚀在应力腐蚀裂纹中的作用的新概念，该概念基于不断增长的坑引起局部动态塑性应变，这是应力腐蚀裂纹发展的关键因素。然后概述了量化新出现的小裂纹的后续生长速度的挑战，其中潜在滴技术是最可行的。比较了短裂纹（断裂力学试样中的透厚裂纹）和长裂纹的扩展速率，并利用电化学裂纹尺寸效应对数据进行了合理化分析。
In many applications, corrosion pits act as precursors to cracking, but qualitative and quantitative prediction of damage evolution has been hampered by lack of insights into the process by which a crack develops from a pit. An overview is given of recent breakthroughs in characterization and understanding of the pit-to-crack transition using advanced three-dimensional imaging techniques such as X-ray computed tomography and focused ion beam machining with scanning electron microscopy. These techniques provided novel insights with respect to the location of crack development from a pit, supported by finite-element analysis. This inspired a new concept for the role of pitting in stress corrosion cracking based on the growing pit inducing local dynamic plastic strain, a critical factor in the development of stress corrosion cracks. Challenges in quantifying the subsequent growth rate of the emerging small cracks are then outlined with the potential drop technique being the most viable. A comparison is made with the growth rate for short cracks (through-thickness crack in fracture mechanics specimen) and long cracks and an electrochemical crack size effect invoked to rationalize the data.