Stress corrosion cracking carbide precipitation

Type 321 stainless steel can be used with improved corrosion resistance wherever type 316 is suitable, particularly in the presence of nitric acid. This alloy is particularly useful in high-temperature service in the carbide precipitation range and for parts heated intermittently between 800 and 1650T (428-899°C). Even with the overall improved corrosion resistance it still may be susceptible to chloride stress corrosion cracking. Table 10.5 provides the compatibility of type 321 stainless with selected corrodents. 

HASTELLOY alloy B-2—An improved wrought version of HASTELLOY alloy B. Alloy B-2 has the same excellent corrosion resistance as alloy B, but with improved resistance to knife-line and heat-affected zone attack This alloy resists the formation of grain-boundary carbide precipitates in the weld heat-affected zone, thus making it suitable for most chemical process applications in the as-welded condition. Alloy B-2 also has excellent resistance to pitting and stress-corrosion cracking it is particularly well suited for equipment handling hydrogen chloride gas. and hydrochloric, sulfuric, acetic, and phosphoric acids. 

K. Arioka, T. Yamada, T. Miyamoto, T. Terachi, Dependence of stress corrosion cracking of alloy 600 on temperature, cold work, and carbide precipitation, the role of diffusion of vacancies at crack tips, Corrosion 67 (3) (2011) 035006-11—035006-18. 

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