SAFTM 2205 is a duplex (austenitic-ferritic) stainless steel for OCTG downhole applications.
The grade is characterized by:
- High resistance to stress corrosion cracking (SCC) in chloride-bearing environments
- Moderate resistance to SCC in sour (H2S/Cl-) environments
- High resistance to general corrosion, pitting, and crevice corrosion
- High mechanical strength – roughly twice the proof strength of austenitic stainless steel
- UNS: S31803, S32205
- EN Number: 1.4462
- ISO: 4462-318-03-I
Product standards
Seamless tubes used as casing, tubing and coupling stock:
- ISO 13680, PSL-1 and PSL-2
- API spec 5CRA, PSL-1 and PSL-2
Approvals
- NACE MR0175/ISO 15156 (Petroleum and natural gas industries - Materials for use in H2S-containing Environments in oil and gas production - Part 3: Cracking-resistant CRAs (corrosion resistant alloys and other alloys) (Published:2015)
- SAF 2205 grade 65 ksi, 110 ksi, and 125 ksi, (PSL-1 or PSL-2) and grade 140 ksi (PSL-1) can be delivered with API-5CRA Monogram (License Number 5CRA-0016)
Chemical composition (nominal)
| C | Si | Mn | P | S | Cr | Ni | Mo | N |
|---|---|---|---|---|---|---|---|---|
| ≤0.03 | ≤1.0 | ≤2.0 | ≤0.03 | ≤0.015 | 22 | 0.18 | 3.2 | 0.18 |
Applications
SAF™ 2205 is used for high strength downhole production tubing, casing, and liners in sour gas wells. This includes environments with high temperatures, high partial pressures of CO2 and H2S, and high chloride concentrations. The material is suitable for use in production tubing and flowlines for the extraction of oil and gas from sour wells, in refineries and in process solutions contaminated with chlorides.
The high strength of SAF™ 2205 makes the material an attractive alternative to the austenitic steels in structures subjected to heavy loads.
Corrosion resistance
Pitting Corrosion
SAF™2205 can withstand high temperatures in aggressive environments without pitting. A recognized method of ranking a material's susceptibility to localized corrosion is by means of the PRE number (Pitting Resistance Equivalent). This PRE number is based on the contents of chromium, molybdenum and nitrogen in the alloy according to the following formula:
PRE = %Cr + 3.3 × %Mo + 16 × %N
A PRE number is the relative measure of a material's ability to resist pitting corrosion in chloride containing environments. The PRE number for SAF™ 2205 is compared with other materials in the following table:
| Grade | % Cr | % Mo | % N | PRE |
| SAF 2205 | 22 | 3.2 | 0.18 | >35 |
| UNS S31803 | 21.0 - 23.0 | 2.50 - 3.50 | 0.08 - 0.20 | >30 |
| Alloy 825 | 20 | 2.6 | - | 29 |
| ASTM TP317L | 18 | 3.5 | - | 30 |
| ASTM TP316L | 17 | 2.2 | - | 24 |
SAF™ 2205 has a minimum PRE number of 35, which confirms its high resistance to pitting corrosion when chlorides are present.
Stress Corrosion Cracking (SCC)
The standard austenitic steels ASTM TP304L and ASTM TP316L are prone to stress corrosion cracking (SCC) in chloride-bearing solutions at temperatures above 60°C (140°F).
Figure 7. Resistance to stress corrosion cracking (SCC) in neutral chloride solutions with an oxygen content of about 8 ppm. Laboratory results for SAF™ 2205 of constant load specimens loaded to the proof strenth at the test temperature.
Duplex stainless steels are far less prone to this type of corrosion. Laboratory tests reveal good resistance to stress corrosion cracking of SAF™ 2205. Results from the tests are presented in Figure 7. The diagram indicates the temperature-chloride range within which SAF™ 2205 and the standard steels ASTM TP304L and ASTM TP316L have low susceptibility to stress corrosion cracking.
Fabrication
SAF™ 2205 tubes are supplied in the cold worked condition and are intended for use with threaded connections.
Forms of supply
Materials for oil and gas production
Cold hardened (cold worked) seamless tube and pipe
For production tubing, casing, liner, and coupling stock for downhole oil and gas applications, SAF™ 2205 is supplied solution annealed (65 ksi) or cold hardened with high strength properties. (110 ksi, 125 ksi, 140 ksi).
Full details on sizes, finishes and mechanical properties are available on request. Email: stog.smt@alleima.com
Mechanical properties
At 20°C (68°F)
Metric and imperial units
| Grade | Proof strength | Tensile Strength | Elongation | Hardness | ||
| Rp0.2a) | Rm | A2” | HRC | |||
| MPa | ksi | MPa min | ksi min | % min | % max | |
| PSL-1 SAF2205-65 | 448 - 621 | 65 - 90 | 621 | 90 | 25 | 26 |
| PSL-1 SAF2205-110 | 758 - 965 | 110 - 140 | 862 | 125 | 11 | 36 |
| PSL-1 SAF2205-125 | 862 - 1034 | 125 - 150 | 896 | 130 | 10 | 37 |
| PSL-1 SAF2205-140 | 965 - 1103 | 140 - 160 | 1000 | 145 | 9 | 38 |
| PSL-2 SAF2205-65 | 448 - 621 | 65 - 90 | 621 | 90 | 25 | 26 |
| PSL-2 SAF2205-110 | 758 - 965 | 110 - 140 | 862 | 125 | 11 | 36 |
| PSL-2 SAF2205-125 | 862 - 1000 | 125 - 145 | 896 | 130 | 10 | 36 |
1 MPa = 1 N/mm2
a) Rp0.2 corresponds to 0.2% offset yield strength.
At high temperatures
SAFTM 2205 shows very good mechanical properties at higher temperatures. Further information is available on request. Email: stmo.smt@alleima.com
Metric units / Imperial units
| Temperature °C | De-rating factor* | Temperature °F | De-rating factor* |
| 20 | 1.00 | 68 | 1.00 |
| 50 | 0.85 | 122 | 0.85 |
| 100 | 0.74 | 212 | 0.74 |
| 150 | 0.69 | 302 | 0.69 |
| 200 | 0.63 | 392 | 0.63 |
Physical properties
Density, at 7.8 g/cm3, 0.28 lb/in3
Thermal conductivity
Metric units
| Temperature,°C | 20 | 100 | 200 | 300 | 400 |
| W/(m °C) | |||||
| SAFTM 2205 | 14 | 16 | 17 | 19 | 20 |
| ASTM TP316L | 14 | 15 | 17 | 18 | 20 |
Imperial Units
| Temperature,°F | 68 | 200 | 400 | 600 | 800 |
| Btu/(ft h °F) | |||||
| SAFTM 2205 | 8 | 9 | 10 | 11 | 12 |
| ASTM TP316L | 8 | 9 | 10 | 10 | 12 |
Specific Heat Capacity
Metric units
| Temperature,°C | 20 | 100 | 200 | 300 | 400 |
| J/(kg °C) | |||||
| SAFTM 2205 | 480 | 500 | 530 | 550 | 590 |
Imperial Units
| Temperature,°F | 68 | 200 | 400 | 600 | 800 |
| Btu/(lb °F) | |||||
| SAFTM 2205 | 0.11 | 0.12 | 0.13 | 0.13 | 0.14 |
Thermal Expansion
Metric units, x10-6/°C
| Temperature, °C | 30-100 | 30-200 | 30-300 | 30-400 |
| Per °C | ||||
| SAFTM 2205 | 13.0 | 13.5 | 14.0 | 14.5 |
| Carbon steel | 12.5 | 13.0 | 13.5 | 14.0 |
| ASTM TP316L | 16.5 | 17.0 | 17.5 | 18.0 |
Imperial units, x10-6/°F
| Temperature, °F | 86-200 | 86-400 | 86-600 | 86-800 |
| Per °F | ||||
| SAFTM 2205 | 7.0 | 7.5 | 8.0 | 8.0 |
| Carbon steel | 6.8 | 7.0 | 7.5 | 7.8 |
| ASTM TP316L | 9.0 | 9.5 | 9.8 | 10.0 |
Resistivity
Metric units
| Temperature, °C | 20 | 100 | 200 | 300 |
| μΩm | ||||
| SAFTM 2205 | 0.74 | 0.85 | 0.96 | 1.00 |
Imperial units
| Temperature, °F | 68 | 200 | 400 | 600 |
| µΩin | ||||
| SAFTM 2205 | 29.1 | 33.1 | 39.8 | 43.3 |
Modulus of elasticity
Metric units, x103
| Temperature, °C | 20 | 100 | 200 | 300 |
| MPa | ||||
| SAFTM 2205 | 200 | 194 | 186 | 180 |
Imperial units, x103
| Temperature, °F | 68 | 200 | 400 | 600 |
| ksi | ||||
| SAFTM 2205 | 29.0 | 28.2 | 27.0 | 26.2 |
Impact Strength
SAF™ 2205 possesses good impact strength both at room temperature and at low temperatures, as is evident from Figure 1. The values apply for standard Charpy-V specimens (10 x 10 mm, 0.39 x 0.39 in.).
Figure 1. Curve showing typical impact strength values (Charpy-V) for SAF 2205. Specimen size 10x10mm (0.39 x 0.39 in.).
Disclaimer: Recommendations are for guidance only, and the suitability of a material for a specific application can be confirmed only when we know the actual service conditions. Continuous development may necessitate changes in technical data without notice. This datasheet is only valid for Alleima materials.