Combining many of the beneficial properties of both ferritic and austenitic steels, 2205 is the most widely used duplex stainless steel grade. Its high chromium and molybdenum content gives the stainless steel excellent corrosion resistance. The microstructure provides resistance to stress corrosion cracking and ensures high strength.
The grade is generally not suitable for use at temperatures above 300oC or below -50oC because of reduced toughness outside this range. You are most likely to encounter 2205 stainless steel being used in industrial environments such as petrochemical, chemical, oil, gas and paper plants.
2205 has been available for several years - in general this complies with UNS grade designation S31803. More recently, product has become available complying with the higher corrosion resistant composition UNS S32205, as in table 1. Both these alternatives are known as 2205.
Grade 2205 has a micro structure of roughly equal amounts of ferrite and austenite, hence the 'duplex' description. The duplex structure of 2205 has the following properties:
* High strength.
* Lower thermal expansion co-effecient than austenitic steels but greater than carbon steels.
* High resistance to corrosion, particularly stress corrosion cracking, corrosion fatigue and erosion.
The high content of chromium and molybdenum and the addition of nitrogen gives the steel further beneficial characteristics:
* High general corrosion resistance.
* High pitting and crevice corrosion resistance.
* Good sulphide stress corrosion cracking resistance.