Abstract by Sarah Young
Physics and Astronomy
Time reversed elastic nonlinearity diagnostic applied to stress corrosion cracking in stainless steel
The Time Reversed Elastic Nonlinearity Diagnostic (TREND) is an inspection technique that enables one to locate damage in a structure using time reversal processing. TREND has been used to detect various types of damage in metals and rocks, but little has been done specific to stress corrosion cracking (SCC). SCC in stainless steel, especially around welds, is produced as a result of elevated temperature and saline conditions, and so has different properties from fatigue cracking or delaminations, both of which have been studied with TREND. In current research, welded steel samples exposed to a magnesium chloride bath were created. A number of samples were exposed for successively longer durations in order to study the corrosion damage level versus exposure time. Using TREND, samples were scanned then evaluated for indicators of local cracking at each scan point. Specific changes in spectral characteristics that are indicators of cracking were found to correlate to a longer exposure time and therefore the extent of SCC damage at that location.