Alloy 2205 is a 22% Chromium, 3% Molybdenum, 5-6% Nickel nitrogen alloyed duplex stainless steel with high general, localized and stress corrosion resistance properties in addition to high strength and excellent impact toughness.
Alloy 2205 provides pitting and crevice corrosion resistance superior to 316L or 317L austenitic stainless steels in almost all corrosive media. It also has high corrosion and erosion fatigue properties as well as lower thermal expansion and higher thermal conductivity than austenitic.
The yield strength is about twice that of austenitic stainless steels. This allows a designer to save weight and makes the alloy more cost competitive when compared to 316L or 317L.
Alloy 2205 is particularly suitable for applications covering the -50°F/+600°F temperature range. Temperatures outside this range may be considered but need some restrictions, particularly for welded structures.
Applications
Pressure vessels, tanks, piping, and heat exchangers in the chemical processing industry
Piping, tubing, and heat exchangers for the handling of gas and oil
Effluent scrubbing systems
Pulp and paper industry digesters, bleaching equipment, and stock-handling systems
Rotors, fans, shafts, and press rolls requiring combined strength and corrosion resistance
Cargo tanks for ships and trucks
Food processing equipment
Biofuels plants
Standards
ASTM/ASME...........A240 UNS S32205/S31803
EURONORM...........1.4462 X2CrNiMoN 22.5.3
AFNOR...................Z3 CrNi 22.05 AZ
DIN.........................W. Nr 1.4462
Processing
Hot Forming
Forming below 600°F is recommended whenever possible. When hot forming is required, the workpiece should be heated uniformly and worked in the range of 1750 to 2250°F. Alloy 2205 is quite soft at these temperatures and is readily formed. Above this range, 2205 is subject to hot tearing. Immediately below this range, the austenite becomes substantially stronger than the ferrite and may cause cracking, a particular danger to “cold” edges. Below 1700°F there can be rapid formation of intermetallic phases because of the combination of temperature and deformation. Whenever hot forming is done, it should be followed by a full solution anneal at 1900°F minimum and rapid quench to restore phase balance, toughness, and corrosion resistance. Stress relieving is not required or recommended; however, if it must be performed, the material should receive a full solution anneal at 1900°F minimum, followed by rapid cooling or water quenching.
Cold Forming
Alloy 2205 is readily sheared and cold formed on equipment suited to working stainless steels. However, because of the high strength and rapid work hardening of 2205, forces substantially higher than those for austenitic steels are required to cold form 2205. Also because of the high strength, a somewhat larger allowance must be made for springback.
Heat Treatment
Alloy 2205 should be annealed at 1900°F minimum, followed by rapid cooling, ideally by water quenching. This treatment applies to both solution annealing and stress relieving. Stress relief treatments at any lower temperature carry the risk of precipitation of detrimental intermetallic or nonmetallic phases.
