Applications | Standards | Corrosion Resistance | Chemical Analysis
Mechanical Properties | Structure | Processing | Machinability | Welding

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 -50ÅF/+600ÅF temperature range. Temperatures outside this range may be considered but need some restrictions, particularly for welded structures.

• 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

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

Localized Corrosion Resistance
The chromium, molybdenum and nitrogen in 2205 also provide excellent resistance to pitting and crevice corrosion even in very oxidizing and acidic solutions.


Isocorrosion Curves 4 mpy (0.1 mm/yr), in sulfuric
acid solution containing 2000 ppm

Stress Corrosion Resistance
The duplex microstructure is known to improve the stress corrosion cracking resistance of stainless steels.

Chloride stress corrosion cracking of austenitic stainless steels can occur when the necessary conditions of temperature, tensile stress, oxygen and chlorides are present. Since these conditions are not easily controlled stress corrosion cracking has often been a barrier to utilizing 304L, 316L or 317L

Corrosion Fatigue Resistence
Alloy 2205 combones high strength and high corrosion resistance to produce high corrosion fatigue strength. Applications in which processing equipment is subject to both an aggresively corrosive enviroment and to cycle loading can benefit from the properties of 2205.

ritical Pitting Temperature in 1M NaCl Measured
using the AvestaPolarit Pitting Cell

ritical Crevice Corrosion Temperature (CCT)
in 10% FeCl₃•6H₂O

General Corrosion in Wet Process Phosphoric Acids

Stress Corrosion Cracking Resistance

(P= Pass, F= Fail)

Mechanical Properties
Mechanical Properties at Room Temperature

Tensile Properties at Elevated Temperatures

Physical Properties

Structure
The chemical analysis of 2205 is optimized to obtain a typical 50 a / 50 g microstructure after solution annealing treatment at 1040Å/1080ÅC (1900Å/1922ÅF).

Heat treatments performed above 2000ÅF may result in an increase of ferrite content.

Like all duplex stainless steels, 2205 is susceptible to precipitation of intermetallic phases, usually referred to as sigma phase. Intermetallic phases precipitate in the range of 1300ÅF to 1800ÅF, with the most rapid precipitation occurring at about 1600ÅF. Thus, it is prudent to have 2205 pass a test for the absence of intermetallic phases, such as those in ASTM A 923.

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.

Machinability
With high-speed steel tooling, 2205 may be machined at the same feeds and speeds as type 316L. When carbide tooling is used, cutting speeds should be reduced by about 20% relative to the speeds for type 316L. Powerful machines and rigid mounting of tools and parts are essential.

Welding
Alloy 2205 possesses good weldability. The goal of welding 2205 is that the weld metal and heat-affected zone (HAZ) retain the corrosion resistance, strength, and toughness of the base metal. The welding of 2205 is not difficult, but it is necessary to design welding procedures that lead to a favorable phase balance after welding and will avoid precipitation of detrimental intermetallic or nonmetallic phases.

2205 can be welded by: GTAW (TIG); GMAW (MIG); SMAW ("stick" electrode); SAW; FCW; and PAW.

NOTE
2205 Code Plus Two is a registered trademark of AvestaPolarit, Inc. 254 SMO and 654 SMO are registered trademarks of AvestaPolarit Stainless. SAF 2304 is a registered trademark of Sandvik AB.

This technical data and information represents our best knowledge at the time of printing. However, it may be subject to some slight variations due to our ongoing research program on corrosion resistant grades.

We, therefore, suggest that information be verified at time of inquiry or order. Furthermore, in service, real conditions are specific for each application. The data presented here is only for the purpose of description and may only be considered as guarantees when our Company has given written formal approval.