Abstract
Stress corrosion cracking (SCC) investigations of sensitized 304 austenitic stainless steel were conducted using U-bend specimens of 6.45 and 12.85 mm radii of curvature in Samans solution, which represents the polythionic acid solution formed in the petroleum refineries during shutdown as a result of the interaction of the sulfide scale on the steel surface with moisture and oxygen at ambient temperatures. The chemical analysis of the Samans solution revealed that it contained seven different constituents varying in concentration. They are sulfuric, sulfurous, and thionic acids (di-, tri-, tetra-, penta-, and hexathionic acid). The role of each individual constituent of Samans solution on SCC has been studied. The results of the chemical analysis of the test solutions after failure revealed that out of all constituents of the Samans solution, only tetrathionic acid induced stress corrosion failure of sensitized 304 austenitic stainless steel. The metallographic studies of the fractured surfaces conducted by SEM revealed intercrystalline mode of fracture in all the cases in which the samples cracked.
Toward Understanding the Effects of Strain and Chloride Deposition Density on Atmospheric Chloride-Induced Stress Corrosion Cracking of Type 304 Austenitic Stainless Steel Under MgCl2 and FeCl3:MgCl2 Droplets
