Atom-probe Tomography of Surface Oxides in a 20% Cold Worked Stainless Steel Tested Under PWR Primary Water Conditions
Microscopy and Microanalysis
Low potential stress corrosion cracking (LPSCC) of stainless steels is a very important degradation phenomenon in pressurized water reactors (PWRs). Although SCC of austenitic steels (304 and 316) has not been reported yet in operating PWR plants (except from irradiated materials), careful autoclave testing in under controlled environments have confirmed that highly cold-worked stainless steels are susceptible to SCC even in PWR primary water conditions . In order to clarify the corrosion
... hanisms and the role of cold work, it is important to characterize the oxide-matrix interface with the highest level of detail. It is well known that the oxide films formed in steels under these conditions consist of a double-layer structure, with an inner Cr-rich spinel and an outer Fe-rich spinel layer. In Figure 1 , a STEM HAADF image is shown together with an EELS line profile across the oxide layers and into the matrix. Data was acquired in a Jeol 3000F operated at 297kV equipped with a GIF. Probe size was ~1nm and sampling distance 5nm. Collection and convergence angles were 26 and 16mrad respectively. Gatan DM's was used for quantification.