It is an inter crystalline fracture. High concentration of caustic soda NaOH and the material under stress cause it. The stress corrosion cracks follow the grain or crystal
boundaries of the material land failure of the affected part could result.

• Sodium sulphate or sodium nitrate is used for the prevention of caustic embrittlement.

It can be found in high stress area in boiler tube and tube plate connection, riveted head, seam and boiler mountings.