Degradation of Grain Boundary Strength by Oxidation in Alloy 600
Abstract
The degradation of grain boundary strength induced by corrosion is one of the causes of intergranular stress corrosion cracking. The micro tensile testing method for measuring the strength of an individual grain boundary was applied to alloy 600 specimens exposed to simulated PWR primary water. The exposure caused grain boundary oxidation that progressed about 0.2 µm perpendicular to the boundary; and depending on the exposure time, the depth can be over 2 µm. Specimens of dimensions 1×2×4 µm containing one grain boundary were made by focused ion beam (FIB) micro-processing and were tested in tension in an FIB system. Intergranular fracture occurred at 180-300 MPa for an oxidized grain boundary while it did not occur even at 1000 MPa for a non-oxidized grain boundary. It was confirmed by transmission electron microscopy (TEM) that the cracking propagated on the interface between the metal matrix and the intergranular oxide.
- Publication:
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Proceedings of the 15th International Conference on Environmental Degradation of Materials in Nuclear Power Systems — Water Reactors
- Pub Date:
- 2016
- DOI:
- 10.1007/978-3-319-48760-1_89
- Bibcode:
- 2016edmn.conf.1447F
- Keywords:
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- Materials Science