Effect of Polythionic Acid Concentration on Stress Corrosion Cracking of Sensitized 304 Austenitic Stainless Steel

CORROSION ◽  
1983 ◽  
Vol 39 (8) ◽  
pp. 333-338 ◽  
Author(s):  
S. Ahmad ◽  
M. L. Mehta ◽  
S. K. Saraf ◽  
I. P. Saraswat
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Stress Corrosion ◽  
Acid Concentration ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
304 Austenitic Stainless Steel

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.

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