2205 is the most widely used duplex (ferritic/austenitic) stainless steel grade. It finds applications due to both excellent corrosion resistance and high strength. The standard duplex S31803 composition has over the years been refined by many steel suppliers, and the resulting restricted composition range was endorsed as UNS S32205 in 1996. Duplex S32205 gives better guaranteed corrosion resistance, but for much of the Duplex S31803 currently produced also complies with Duplex S32205. 2205 is not generally suitable for use at temperatures above 300ºC as it suffers from precipitation of brittle micro-constituents, nor below -50ºC because of its ductile-to-brittle-transition.

Chemical processing, transport and storage,
Oil and Gas exploration and processing equipment,
Marine and other high chloride environments,
Pulp and paper digesters, liquor tanks and paper machines.

Excellent general corrosion resistance; superior to Grade 316 in most environments. Excellent resistance to localized corrosion including intergranular, pitting and crevice corrosion; the CPT of 2205 is generally at least 35ºC. The grade is also resistant to chloride stress corrosion cracking (SCC) at temperatures of up to about 150ºC. Grade 2205 will often perform well in environments which cause premature failure of austenitic grades. It has better resistance to sea water then Grade 316.

Although 2205 has good high temperature oxidation resistance, this grade - like other duplex stainless steels - suffers from embrittlement if held for even short times at temperatures above 300ºC. If embrittled, this can only be rectified by a full solution annealing treatment. Duplex stainless steels are almost never used above 300ºC.

Solution treatment (annealing) - heat to 1020ºC-1100ºC and cool rapidly. This grade cannot be hardened by thermal treatment, but does work harden.