Intergranular stress corrosion cracking alloy

Many instances of intergranular stress corrosion cracking (IGSCC) of stainless steel and nickel-based alloys have occurred in the reactor water systems of BWRs. IGSCC, first observed in the recirculation piping systems (21) and later in reactor vessel internal components, has been observed primarily in the weld heat-affected zone of Type 304 stainless steel. 

Intergranular stress-corrosion cracking (IG-SCC) can occur in some sensitized materials when placed under tensile stress. Thus DL-EPR has been used to study the effects of aging time on the susceptibility of Alloy 600 to IGSCC, as shown in Fig. 41 (39). This work also shows the need to modify the experimental parameters of the test to achieve optimal correlation for alloys other than Type 304SS, in this case lowering the KCNS concentration and the temperature while raising the peak potential and the scan rate. 

Reactors are normally made of low-alloy steel (selected per API Publication 941) and clad or weld overlaid with type 347 (UNS S34700) SS. The stabilized grades (i.e., type 947 or 321 [UNS S32100] SS) are normally used for all stainless equipment in these units to avoid intergranular stress corrosion cracking (SCC) during downtime. Downtime corrosion is discussed in the next section of this chapter, Feed-Effluent Exchangers."... 

Fig. 7.90 Effect of stressing direction on the intergranular stress-corrosion crack path in susceptible high-strength aluminum alloy. Dark boundaries are representative of ones favored for cracking for indicated direction of applied stress. Source Ref 97...

In addition to the known corrosive effects of alkali-metal hydroxide and nitrate solutions, intergranular stress corrosion cracking in unalloyed and low-alloy steels in contact with ammonium carbonate and crude methanol (methanol with low concentration of impurities) has also been observed (Matsukura and Sato 1977 Wendler-Kalsch 1983). When this group of materials comes into contact with various othCT aggressive substances, stress corrosion cracking occurs, primarily with transgranular characteristics. 

Unalloyed and low-alloy steel intergranular stress corrosion cracking (ASTM G 36-87 1987) hydrogen-induced cracking H2 S (NACE TM-01-077 1977)... 

V.Y. Gertsman and S.M. Bruemmer, Study of grain boundary character along intergranular stress corrosion crack paths in austenitic alloys, Acta Materialia 49 1589-1598,2001. 

Little, D. A. and Scully, J. R. An Electrochemical Frtimework to Explain Intergranular Stress Corrosion Cracking in tm Al-5.4% Cu-0.5%Mg-0.5%Ag Alloy," Chemistry and Electrochemistry of Stress Corrosion Cracking A Symposium Honoring the Contributions of R. IV. Staehle, R. H. Jones, Ed., The Minerals, Metals and Materials Society, 2002, pp. 555-571. 

Table 8 Results of intergranular stress corrosion cracking tests with a silicon alloyed 18 8Ni...

By means of CERT tests the influence of microstructure on the stress corrosion cracking behaviour of solution annealed (1100°C/20 min) Alloy 600 in deaerated (< 10 pg/1 oxygen) high purity water at 360-400 °C was examined [158]. Intergranular stress corrosion cracking is always found at these temperatures. Increased carbon contents in the matrix cause a reduction in the percentage of transgranular frac-... 

The Influence of Grain Boundary Chemistry and Structure on the Intergranular Attack and Intergranular Stress Corrosion Cracking of Austenitic Alloys... 

Testing the resistance of unalloyed and low alloy steels to intergranular stress corrosion cracking by attack of nitrate medium welded and unwelded materials) (in German)... 

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