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Using transmission Kikuchi diffraction to study intergranular stress corrosion cracking in type 316 stainless steels
Martina Meisnar1, Arantxa Vilalta-Clemente1, Ali Gholinia2
1University of Oxford, Department of Materials, Parks Road, OX1 3PH Oxford, UK.
Micron (Oxford, England : 1993)
|May 15, 2015
Summary
Transmission Kikuchi diffraction (TKD) offers high-resolution stress corrosion cracking analysis in 316 stainless steel. This advanced technique maps microstructural features like grain boundaries and slip, aiding in understanding material failure mechanisms.
Area of Science:
- Materials Science
- Metallurgy
- Corrosion Science
Background:
- Stress corrosion cracking (SCC) is a critical failure mechanism in stainless steels, particularly in nuclear reactor environments.
- Conventional electron backscatter diffraction (EBSD) has limitations in spatial resolution for detailed SCC analysis.
- Transmission Kikuchi diffraction (TKD) offers enhanced spatial resolution for microstructural characterization.
Purpose of the Study:
- To characterize stress corrosion cracking in type 316 stainless steel using Transmission Kikuchi diffraction (TKD).
- To evaluate the capability of TKD for high-resolution orientation mapping and microstructural analysis of SCC.
- To investigate the relationship between crack propagation and microstructural features.
Main Methods:
- Characterization of 316 stainless steel specimens subjected to SCC in simulated pressurized water reactor (PWR) environments.
- Utilized Transmission Kikuchi diffraction (TKD) for orientation mapping with high spatial resolution (down to 5 nm step size).
- Acquired inverse pole figure (IPFZ) maps, image quality maps, and misorientation maps within short acquisition times (<60 min).
Main Results:
- TKD successfully mapped microstructural features, including grain boundaries, deformation bands, twinning, and slip, in relation to crack location.
- High-resolution analysis enabled measurement of grain boundary misorientation and quantification of plastic deformation at crack tips.
- Detected phenomena such as grain boundary migration and slip transfer near the crack.
- Demonstrated TKD's ability to provide detailed microstructural insights in under 60 minutes.
Conclusions:
- Transmission Kikuchi diffraction (TKD) is a powerful technique for high-resolution characterization of stress corrosion cracking in 316 stainless steel.
- TKD provides critical insights into crack-microstructure interactions, including plastic deformation and grain boundary behavior.
- The method's speed and resolution make it valuable for understanding material degradation in harsh environments.
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