New accelerated test for studying the susceptibility of stainless steels to chloride stress corrosion cracking under salt crust

Abstract

Stress corrosion cracking (SCC) occurring under the salt crust which develops on the surfaces of hot AISI 304 stainless steels (SS) in neutral NaCl solutions with low chloride ions (1500 ppm) was investigated using a new lest technique which incorporated the advantages of slow strain rate test (SSRT) technique applied under Wick test conditions. Type AISI 304 stainless steel specimens were heated at both ends while a glass wool in contact with dilute chloride test solution was wrapped on the middle part of the specimen. Specimens were heated to 100 degrees C temperature and strained at 1.9 x 10(-5) mm s(-1) crosshead speed. Another test was done at 130 degrees C with a 1.38 x 10(-5) mm s(-1) crosshead speed. Under both test conditions the specimens had failed by SCC and the cracks had developed under the salt crust on the surfaces of hot stainless steels. The fracture regions of specimens were examined by scanning electron microscope (SEM). Copyright (C) 1996 Elsevier Science Ltd