As-received 310SS refractory anchors were grayish and scaley but otherwise showed no significant surface scale resulting from the high temperature service. The anchor fractures were brittle appearing with no macroscopic ductility. Metallographic examination of the anchor fractures revealed intergranular fracture, intergranular cracking and grain dropping, suggestive of
polythionic acid stress corrosion cracking (PASCC) from exposure to a condensed aqueous phase containing oxygenated sulfur compounds. The PASCC suggested that the anchors were cracking during downtimes. No significant oxidation or subsurface sulfidation was observed.