Aqueous environment stress cracking corrosion

Resistance to stress-corrosion cracking Commercially pure titanium is very resistant to stress-corrosion cracking in those aqueous environments that usually constitute a hazard for this form of failure, and with one or two exceptions, detailed below, the hazard only becomes significant when titanium is alloyed, for example, with aluminium. This latter aspect is discussed in Section 8.5 under titanium alloys. 

Fig. 7.113 Dependence of stress-corrosion-crack-growth rate on stress intensity of a high-strength aluminum alloy in several aqueous environments. Crack orientation TL (stress in transverse direction crack propagation in longitudinal direction). Source Ref 159...

Prior to the 1960s, stress corrosion cracking and corrosion fatigue were principally under the purview of corrosion chemists and metallurgists, and the primary emphasis was on the response of materials in aqueous environments (e.g., sea/salt water), particularly for SCC because of the relative ease of experimentation. Much of the attention was devoted to the understanding of electrochemical reactions that are associated with metal dissolution, crack nucleation, and time-to-failure under a... 

H. C., Stress Corrosion Cracking of High-Strength Steels in Aqueous Environments, Dissertation, Lehigh University (1987). 

HIC differs from sulfide stress cracking (SSC), which also results from the absorption of hydrogen during corrosion in aqueous H2S environments [127, 128]. Whereas HIC does not require an apphed stress and occurs in low-strength steels, SSC does require an external tensile stress and occurs in high-strength steels or in hard areas associated with the heat-affected zones adjacent to welds. However, SSC cracks in the heat-affected zone can lead to SOHIC in the adjacent base metal. 

J.H. Bulloch, Some effects of yield strength on the stress corrosion cracking behavior of low alloy steels in aqueous environments at ambient temperatures, Eng. Fail. Anal. 11 (2004) 843—856. 

Sulfide stress cracking (SSCC) has special importance in the gas and oil industry, as the materials being processed there (natural gas and crude oil) often contain a considerable amount of hydrogen sulfide. SSCC is a low-temperature effect of H2S in an aqueous environment, and sulfidation is the term used for high-temperature (>250°C) sulfur corrosion. In gas pipelines, if the gas is sweet... 

In practice, inhibitors are often defined according to their field of application. In aqueous environments, inhibitors for acid environments are typically used to minimize metal corrosion during pickling of steel, an operation that removes oxide scales by dissolution in an acid. In the petroleum industry, large quantities of inhibitors for acid environments are used to avoid corrosion of drilling equipment. Inhibitors for neutral environments are used above all for the protection of cooling-water circuits. Inhibitors not only reduce the rate of uniform corrosion, but they also serve to protect metals from localized corrosion and stress corrosion cracking [18]. 

Pure magnesium can be considered immune to stress-corrosion cracking (SCC) in both atmospheric and aqueous environments, with no reported failures occurring when loaded to its yield strength [5,26],... 

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