Stress Corrosion Cracking of Sensitized 304 Austenitic Stainless Steel in Sulfurous Acid

CORROSION ◽  
1981 ◽  
Vol 37 (7) ◽  
pp. 412-415 ◽  
Author(s):  
S. Ahmad ◽  
M. L. Mehta ◽  
S. K. Saraf ◽  
I. P. Saraswat
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Chemical Species ◽  
Corrosion Cracking ◽  
Intergranular Cracking ◽  
Sulfurous Acid ◽  
Ambient Temperatures ◽  
304 Austenitic Stainless Steel

Abstract Stress corrosion cracking investigations on U-bend samples of sensitized 304 austenitic stainless steel have been conducted in sulfurous acid solutions in the concentration range, 0.40 to 10% at ambient temperatures. Samples were found to fracture in solutions of more than 3% sulfurous acid. Chemical analysis of solutions after tests showed appreciable reduction in concentration of H2SO3, formation of H2SO4, and also the presence of Fe, Cr, and S ions. Some model experiments were carried out to ascertain the chemical species causing stress corrosion cracking and the role of oxygen and FeS in generating them. Bubbling of oxygen gas through (1) solution of H2SO3 with sample, (2) distilled water with FeS chips, and (3) solution of H2SO3 with FeS chips and sample, resulted in the formation of tetrathionic acid. Results indicate that the sulfurous acid does not directly cause cracking but it is the tetrathionic acid formed by either the interaction of sulfurous acid and austenitic stainless steel or the interaction of FeS and oxygen, that is responsible for cracking. Metallorgraphic examinations of the fracture confirmed intergranular cracking.

Stress Corrosion Cracking of Sensitized 304 Austenitic Stainless Steel in Petroleum Refinery Environment

CORROSION ◽  
1982 ◽  
Vol 38 (6) ◽  
pp. 347-353 ◽  
Author(s):  
S. Ahmad ◽  
M. L. Mehta ◽  
S. K. Saraf ◽  
I. P. Saraswat
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Chemical Analysis ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
Corrosion Failure ◽  
Ambient Temperatures ◽  
304 Austenitic Stainless Steel ◽  
Petroleum Refineries

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.

Intergranular Stress Corrosion Cracking of Austenitic Stainless Steel at Temperatures Below 100 C — A Review

CORROSION ◽  
1982 ◽  
Vol 38 (8) ◽  
pp. 406-424 ◽  
Author(s):  
G. Cragnolino ◽  
D. D. Macdonald
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Pure Water ◽  
Corrosion Cracking ◽  
Intergranular Cracking ◽  
Intergranular Stress Corrosion ◽  
Low Concentrations ◽  
Intergranular Stress Corrosion Cracking

Abstract The environmental and metallurgical factors in the intergranular stress corrosion cracking of austenitic stainless steel at temperatures below 100 C has been examined. The behavior of annealed and sensitized microstructures in a variety of environments, including oxygen-containing pure water and aqueous solutions containing species such as chloride, fluoride, polythionates, and other sulfur species is reviewed. Particular emphasis is placed on the role of sulfur oxyanions as aggressive species that can induce intergranular cracking at very low concentrations in industrial environments. Electrochemical and metallurgical aspects associated with the development of intergranular cracks in these environments are thoroughly discussed, and the mechanistic implications are addressed.

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