Berlin 2012 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 50: Topical Session Modern Atom Probe Tomography IV - Thin Films and Structural Materials

MM 50.4: Vortrag

Donnerstag, 29. März 2012, 12:30–12:45, H 0107

Atom-Probe Tomography of Grain Boundary Oxides in Stressed and Cold-Worked 304 Stainless Steel — •Karen Kruska¹, David W Saxey², George D W Smith¹, Takumi Terachi³, Takuyo Yamada³, and Sergio Lozano-Perez¹ — ¹University of Oxford, Department of Materials, Parks Road, OX1 3PH, UK — ²School of Physics, The University of Western Australia, WA 6009, Australia — ³2Institute of Nuclear Safety System (INSS), 64 Sata, Mihama-cho, Mikata-gun, Fukui 919-1205, Japan

Cold-worked 304 stainless steels (SS) are known to be susceptible to stress corrosion cracking (SCC). This study employs atom-probe tomography (APT) for local chemical analysis of the oxides formed. Autoclave experiments on a set of samples with/without cold-work prior to oxidation, and with/without stress applied during oxidation, were carried out under simulated pressurised water reactor (PWR) primary conditions. APT and analytical transmission electron microscopy (ATEM) were combined to investigate chemical and structural implications of surface and grain boundary oxidation in 304 SS. Focussed ion beam (FIB) milling was used to prepare specimens containing the same grain boundary for every analysis technique. Grain boundary and deformation band oxidation were observed in all but the unstressed and non-cold worked sample. Hydrogen associated to the Nickel-rich regions and cavities was found ahead of the Cr-rich oxide in some of the samples. The implications of these findings to current SCC models will be discussed.