These are stainless steels containing relatively high chromium (between 18 and 28%) and moderate amounts of nickel (between 4.5 and 8%). The nickel content is insufficient to generate a fully austenitic structure and the resulting combination of ferritic and austenitic structures is called duplex. Most duplex steels contain molybdenum in a range of 2.5 - 4%.
Basic properties
- High resistance to stress corrosion cracking
- Increased resistance to chloride ion attack
- Higher tensile and yield strength than austenitic or ferritic steels
- Good weldability and formability
Common uses
- Marine applications, particularly at slightly elevated temperatures
- Desalination plant
- Heat exchangers
- Petrochemical plant
Common duplex grades and their applications
