Elastic-Plastic Fracture Mechanics Analysis on Environmentally Accelerated Cracking of Stainless Steel in High Temperature Water

1985 ◽  
Vol 107 (3) ◽  
pp. 240-245 ◽  
Author(s):  
T. Kawakubo ◽  
M. Hishida
Keyword(s):  
Stainless Steel ◽  
High Temperature ◽  
Fracture Mechanics ◽  
Stress Corrosion ◽  
Crack Growth ◽  
Mechanistic Model ◽  
304 Stainless Steel ◽  
Elastic Plastic ◽  
Oxygenated Water ◽  
Type 304

Stress corrosion crack growth during slow strain rate testing was investigated using elastic-plastic fracture mechanics. Thin compact and center-notched specimens of sensitized Type 304 stainless steel were examined at different extension rates in high temperature oxygenated water. The analytical results showed that the crack growth rate has a best correlation with a time differential of the J-integral, which is an estimate of a crack tip deformation rate. Based on the analysis, a new mechanistic model under both monotonic and cyclic loadings was suggested, where cracking was classified into three categories depending on the environmental acceleration, i.e., mechanical cracking, corrosion enhanced mechanical cracking, and stress corrosion cracking.

The Benefit of Hydrogen Addition to the Boiling Water Reactor Environment on Stress Corrosion Crack Initiation and Growth in Type 304 Stainless Steel

1986 ◽  
Vol 108 (1) ◽  
pp. 10-19 ◽  
Author(s):  
C. W. Jewett ◽  
A. E. Pickett
Keyword(s):  
Stainless Steel ◽  
High Temperature ◽  
Fracture Mechanics ◽  
Crack Initiation ◽  
Stress Corrosion ◽  
Crack Growth ◽  
304 Stainless Steel ◽  
Full Size ◽  
Type 304 ◽  
Type 304 Stainless Steel

Intergranular Stress Corrosion Cracking (IGSCC) in Type 304 stainless steel in high temperature high purity water requires the simultaneous presence of sensitized material, high tensile stress and oxygen. Laboratory and in-reactor stress corrosion tests have shown the benefits of adding hydrogen to the boiling water reactor feed-water to reduce the dissolved oxygen concentration and thereby reduce the chemical driving force for IGSCC. The purpose of this program was to verify the benefit of hydrogen additions on the stress corrosion crack behavior. The program investigated the fatigue and constant load crack growth behavior using fracture mechanics specimens in hydrogen water chemistry (HWC). Isothermal heat treatments were used to sensitize Type 304 stainless steel. Additionally, full size pipe tests containing actual welds were used to evaluate crack initiation, as well as propagation of cracks, to verify the results of the fracture mechanics tests. These pipe tests were performed under a trapezoidal loading cycle. The results of the small specimen tests show that HWC inhibits IGSCC in Type 304 stainless steel. The effects of cyclic loading at slow frequencies which promote IGSCC were also evaluated. Computer aided methods were used in the collection and interpretation of the high temperature crack growth data. The full-size component tests substantiated the benefit of HWC in both crack initiation and growth. All results presented were compared to baseline test data to put the results into perspective.

Stress Corrosion Cracking of Sensitized Type 304 Stainless Steel in High-Temperature Water with Anionic Impurities Contamination

CORROSION ◽  
10.5006/0690 ◽  
2012 ◽  
Vol 68 (12) ◽  
pp. 1094-1107 ◽  
Author(s):  
F. Scenini ◽  
A. Sherry
Keyword(s):  
Stainless Steel ◽  
High Temperature ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Cold Work ◽  
Corrosion Cracking ◽  
304 Stainless Steel ◽  
Localized Deformation ◽  
Type 304 ◽  
Type 304 Stainless Steel

This paper describes some results selected from a larger program that was aimed at understanding the stress corrosion cracking (SCC) initiation of Type 304 stainless steel (UNS S30400) in high-temperature deaerated water. Out of a large number of statically loaded samples, only a small minority of the tested samples underwent SCC. The occurrence of SCC indicates a synergism between sensitization, ionic impurities (mainly chloride and sulfate), and/or superficial defects and cold work. In fact, none of the nonsensitized materials initiated cracking (within the time scale of the tests), while only three sensitized samples underwent extensive SCC. The crack morphology of the fractured sample was predominantly inter-granular with some transgranular regions. Transmission electron microscopic samples containing crack tips were, in most respect, in line with the literature: a magnetite/spinel duplex layer on the crack surfaces, a Cr-rich oxide at the crack tip, and Ni enrichment at the metal/oxide interface and oxidized deformation bands intercepting the crack flanks. Also, finger-like features protruding several hundreds of nanometers along the slip planes intersecting the intergranular crack were found on grain boundaries with a high degree of localized deformation. These results support the theory that cracking initiation and propagation might be associated with the formation of oxide on crystallographic planes inside the material.

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