Synchrotron X-ray Fluorescence Imaging Study on Chloride-Induced Stress Corrosion Cracking Behavior of Austenitic Stainless Steel Welds Via Selective Corrosion of Δ-Ferrite

Chloride-induced stress corrosion cracking (CISCC) is a degradation of austenitic stainless steels by Cl-containing media, residual stress, and materials susceptibility. In this study, synchrotron X-ray fluorescence imaging and electron microscopy were utilized to investigate the CISCC mechanism in austenitic stainless steel welds 304 LER308L and 316 L-ER316L. Specimens were exposed to 60 degrees C and 30% relative humidity conditions for 3 months and their microstructure and chemistry were analyzed. Since 6-ferrite is composed of ferrite formers especially Cr and acts as a sink for impurities, selective corrosion of 6-ferrite results in pitting corrosion and CISCC propagation.