Stress corrosion cracking surface treatments

Since a tensile component of stress is required, stress corrosion cracking can be prevented by putting the surface of a component into compression, e.g., by short-peening. Where this is practicable, it is desirable. The treatment needs to be applied uniformly. It will not be effective if pitting occurs on the compressed layer. 

Corrosion resistant steel (CRES) (300-400 series) Intergranular corrosion (due to improper heat treatment). Some tendency to pitting in marine environment (300 series more corrosion resistant than 400 series). Stress corrosion cracking Corrosion evidenced by rough surface sometimes by red, brown, or black stain... 

In addition to ferritic-austenitic steels (duplex steels), austenitic CrNiMo steels can also be used in waste water treatment plants. These steels are sufficiently passive in most waste waters so that uniform surface corrosion can be practically neglected however, under critical conditions, they can exhibit local corrosive attack in the form of pitting corrosion, crevice corrosion, or stress corrosion cracking. The decisive evaluation criteria for their possible application with respect to the media... 

Studies have been conducted on the effects of corrosive salt-spray environment on bondlines of different bonded systems. The system variations included clad and bare alloys, surface treatments, adhesive primers, and adhesives. Five specimens were fabricated for each of the bonded systems. The specimens were then placed in a salt-spray environment of 5% NaCl at 35 °C. The change in wedge-test crack length of each specimen was recorded periodically. At the end of 1 month, one specimen was randomly selected from each bonded system and opened for visual inspection of the bondline condition, both in the stressed zone (crack-tip zone) and in the unstressed zone. The same procedure was carried out after 2, 3, 6, and 12 months, when the last specimen was removed from test. The conclusions were as follows... 

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