Case 3
- Introduction
- Causes of Defects
- Good Practices
- Standards
- Maintenance and Diagnostics
- Remedial
- Similar Cases
- References
Cause of Defects
Stainless steel, which is also known as inox, corrosion-resistant steel (CRES), is an iron alloy renowned for its resistance to rust and corrosion. This alloy includes iron combined with chromium and elements such as molybdenum, carbon, nickel and nitrogen, depending on its specific application and cost requirements. The corrosion resistance of stainless steel is primarily due to its chromium content, which is 10.5% or higher. This chromium forms a passive film that protects the material and has the ability to self-heal when exposed to oxygen.
This layer prevents further corrosion on the surface. The more chromium is added to the metal, the more resistance you get to oxidation and corrosion.
However, when high contents of sulphide and chloride ions are presented in the the environment, chlorides can attack and destroy the passive film and form corrosion products or pitting. When exposed to too much heat or moisture e.g. near hot water tanks, localised areas may be susceptible to stress corrosion cracking.