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Zajec (2020): Stress corrosion crack initiation testing with tapered specimens in high-temperature waterresults of a collaborative research project, Corrosion Engineering, Science and Technology,

In situ transmission electron microscopy (TEM) has become an increasingly important research area in materials science with the advent of unique microscope platforms and a range of specialized in situ specimen holders. The ability to image and perform x-ray energy dispersive spectroscopy (XEDS) analyses of metals in liquids are particularly important for detailed study of the metal-environment interactions with specific microstructural features. In particular, these capabilities now make it feasible to explore what has been termed "SCC precursor phenomena"-that is, those sub-micron scale reactions between an alloy of interest and the environment. This topic is especially timely for this Swann Memorial Symposium, as Peter Swann's activities in this area, particularly in the 1970's concerning the initiation and early stages of transgranular SCC in austenitic stainless steels, were clearly prescient. In this study, we have used liquid cell TEM with XEDS to explore the "precursor phenomena" that can promote the development of defect initiation in Type 304 austenitic stainless steel. For this work, the FIB lift-out technique was used to extract specimens to be studied in the liquid cell TEM specimen holder. This technique has been applied to examine the localised dissolution of MnS inclusions, which can lead to pit initiation.

S. (2018). High-resolution characterisation of austenitic stainless steel in PWR environments: effect of strain and surface finish on crack initiation and propagation. In AbstractInitiation and propagation of cracks under simulated primary water conditions and different slow strain rates have been studied for an austenitic 304-type stainless steel. Two surface finishes were used to better understand the conditions that trigger stress corrosion cracking (SCC).The main objective is to identify the mechanism(s) that govern the initiation and propagation of SCC and the influence of microstructure. Crack morphology, stress localisation and local chemical composition were characterized for all samples studied. The characterization methodology includes scanning electron microscopy (SEM), 3D focused ion beam (FIB), Transmission Kikuchi Diffraction (TKD), and analytical scanning transmission electron microscopy (STEM).