Abstract
A novel approach has been designed to observe stress corrosion cracking (SCC) as it occurs in-situ, in real time. State-of-the-art contact mode high-speed atomic force microscopy (HS-AFM) has been utilised to measure in-situ SCC propagation with nanometre resolution on AISI Type 304 stainless steel in an aggressive salt solution. SCC is an important failure mode in many metal systems but has a complicated mechanism that makes failure difficult to predict. Prior to the in-situ experiments, the contributions of microstructure, environment and stress to SCC were independently studied using HS-AFM. Uplift of grain boundaries before cracking was observed, indicating a subsurface contribution to the cracking mechanism. Focussed ion beam milling revealed a network of intergranular
cracks below the surface lined with a thin oxide, indicating that the SCC process is dominated by local stress at oxide-weakened boundaries. Subsequent analysis by atom probe tomography of a crack tip showed a thin Cr-rich oxide at the surface of the open crack. This study shows how in-situ HS-AFM observations in combination with complementary techniques can give new insight into the mechanisms of SCC.
cracks below the surface lined with a thin oxide, indicating that the SCC process is dominated by local stress at oxide-weakened boundaries. Subsequent analysis by atom probe tomography of a crack tip showed a thin Cr-rich oxide at the surface of the open crack. This study shows how in-situ HS-AFM observations in combination with complementary techniques can give new insight into the mechanisms of SCC.
Original language | English |
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Article number | 3 |
Number of pages | 10 |
Journal | npj Materials Degradation |
Volume | 5 |
Issue number | 1 |
DOIs | |
Publication status | Published - 18 Jan 2021 |
Bibliographical note
Funding Information:The authors would like to thank Dr. Scott Greenwell for providing an optical stitch of the sample, the physics workshop and the NSQI low noise labs at the University of Bristol. The PhD studentship for S.M. was funded by the National Nuclear Laboratory (NNL) and the Engineering and Physical Sciences Research Council (EPSRC). O.P. was supported by a fellowship awarded by the Royal Academy of Engineering (RAEng). EPSRC funding for the LEAP 5000XR atom probe for the UK National Atom Probe Facility was provided under the grant number EP/M022803/1.
Publisher Copyright:
© 2021, The Author(s).
Research Groups and Themes
- Engineering Mathematics Research Group
Keywords
- atomic force microscopy
- characterization and analytical techniques
- corrosion
- scanning probe microscopy
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