Sandvik SAF 2205™ PM is a powder metallurgical duplex (austenitic-ferritic) stainless steel manufactured by Hot Isostatic Pressing (HIP). Applications include offshore components and the grade is characterized by:
- High resistance to stress corrosion cracking (SCC) in chloride and CO2 containing environments
- High resistance to pitting owing to its high PRE* value of 35 minimum
- High resistance to general corrosion
- High tensile strength
* PRE = % Cr + 3.3 x % Mo + 16 x % N
Standards
- UNS: S31803, S32205
- EN Number: 1.4462
Product standards
- Suitable for the production of flanges and forged fittings according to ASTM A182.
Approvals
- NACE MR0175/ISO 15156
- ASME B31.3.
Sandvik SAF 2205™ PM is qualified according to NORSOK M650 rev 4.
Chemical composition (nominal) %
| C | Si | Mn | P | S | Cr | Ni | Mo | N |
|---|---|---|---|---|---|---|---|---|
| ≤0.030 | ≤1.0 | ≤2.0 | ≤0.030 | ≤0.015 | 22 | 5 | 3.2 | 0.18 |
Forms of supply
Components can be supplied in a wide range of dimensions and shapes because of the flexibility provided by powder metallurgy and near net shape technology. The products are supplied in the solution annealed and water quenched condition.
Mechanical properties
Hot isostatic pressed components have isotropic properties, meaning the mechanical properties are similar in all directions.
| Proof strength*, Rp0.2 | ≥450 MPa ≥65 ksi |
| Tensile strength*, Rm | ≥655 MPa ≥95 ksi |
| Elongation, A, min.* | ≥25% |
| Reduction of area, Z, min.* | ≥25% |
| Impact strength CVN +20ºC -46ºC |
≥150J, ≥110 ft lb ≥70 J, ≥ 52 ft lb |
| Hardness HRC | ≤25 |
* Minimum values according to ASTM 988.
Impact strength values valid for round bar in diameters up to 200 mm.
| Temperature | Proof strength* Rp0.2 |
|
|---|---|---|
| ºC | MPa | ksi |
| 50 | ≥415 | ≥60 |
| 100 | ≥360 | ≥52 |
| 150 | ≥335 | ≥48 |
| 200 | ≥310 | ≥45 |
Physical properties
Density: 7.8 g/cm3, 0.28 lb/in3
| Temperature, ºC | J/(kg ºC) | Temperature, ºF | Btu/(lb ºF) |
|---|---|---|---|
| 20 | 480 | 68 | 0.11 |
| 100 | 500 | 200 | 0.12 |
| 200 | 530 | 400 | 0.13 |
| 300 | 550 | 600 | 0.13 |
| 400 | 590 | 800 | 0.14 |
| Temperature, ºC | 20 | 100 | 200 | 300 | 400 |
|---|---|---|---|---|---|
| W/(m ºC) | |||||
| Sandvik SAF 2205 PM | 14 | 16 | 17 | 19 | 20 |
| ASTM 316L | 14 | 15 | 17 | 18 | 20 |
| Temperature, ºF | 68 | 200 | 400 | 600 | 800 |
|---|---|---|---|---|---|
| Btu/(ft h ºF) | |||||
| Sandvik SAF 2205 PM | 8 | 9 | 10 | 11 | 12 |
| ASTM 316L | 8 | 9 | 10 | 10 | 12 |
| Temperature, ºC | 30-100 | 30-200 | 30-300 | 30-400 |
|---|---|---|---|---|
| Per ºC | ||||
| Sandvik SAF 2205 PM | 13.0 | 13.5 | 14.0 | 14.5 |
| Carbon steel | 12.5 | 13.0 | 13.5 | 14.0 |
| ASTM 316L | 16.5 | 17.0 | 17.5 | 18.0 |
| Temperature, ºF | 86-200 | 86-400 | 86-600 | 86-800 |
|---|---|---|---|---|
| Per ºF | ||||
| Sandvik SAF 2205 PM | 7.0 | 7.5 | 8.0 | 8.0 |
| Carbon steel | 6.8 | 7.0 | 7.5 | 7.8 |
| ASTM 316L | 9.0 | 9.5 | 9.8 | 10.0 |
Sandvik SAF 2205 PM has a far lower coefficient of thermal expansion than austenitic stainless steels and can therefore offer certain design advantages.
Figure 1. Thermal expansion per °C (30-100°C, 85- 210 °F).
| Temperature, ºC | MPa | Temperature, ºF | ksi |
|---|---|---|---|
| 20 | 200 | 68 | 29.0 |
| 100 | 194 | 200 | 28.2 |
| 200 | 186 | 400 | 27.0 |
| 300 | 180 | 600 | 26.2 |
1) (x103)
Corrosion resistance
In most media, Sandvik SAF 2205 PM possesses better resistance to general corrosion than steel of type ASTM 316L and 317L.
Pitting corrosion
Because of the high contents of chromium, molybdenum and nitrogen Sandvik SAF 2205 PM has good pitting and crevice corrosion resistance. A parameter for comparing the resistance of different steels to pitting, is the PRE number (Pitting Resistance Equivalent). The PRE is defined as, in weight-%: PRE = % Cr + 3.3 x % Mo + 16 x % N.
The PRE number for Sandvik SAF 2205 PM is compared with other materials in the following table:
| Grade | % Cr | % Mo | % N | PRE |
|---|---|---|---|---|
| Sandvik SAF 2205 PM | 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 |
* Sandvik SAF 2205 PM has a chemical composition within UNS S32205, which is optimized within the UNS S31803 range in order to provide a high PRE value.
Sandvik SAF 2205 PM meets testing at 25ºC according to ASTM G48A.
Stress corrosion cracking
The standard austenitic steels ASTM 304L and ASTM 316L are prone to stress corrosion cracking (SCC) in chloride-bearing solutions at temperatures above 60°C (140°F).
Duplex stainless steels are far less prone to this type of corrosion.
In aqueous solutions containing hydrogen sulfide and chlorides, stress corrosion cracking can also occur on stainless steels at temperatures below 60°C (140°F). The corrosivity of such solutions is affected by acidity and chloride content.
Sandvik SAF 2205 PM possesses good resistance to stress corrosion cracking in environments containing chlorides as well as in those containing both chlorides and hydrogen sulfide. This has also been confirmed by available operating experience.
Hydrogen induced stress corrosion cracking (HISC)
Powder metal based, hot isostatic pressed duplex stainless steels generally have better resistance to hydrogen induced stress corrosion cracking than forged or cast duplex stainless steel. One reason for this is smaller austenite spacing of the hot isostatic pressed material.
Heat treatment
The products are delivered in the heat-treated condition. If additional heat treatment is needed due to further processing, the following is recommended.
Solution annealing 1060ºC + water quench.
Welding
The weldability of Sandvik SAF 2205 PM is good. Suitable welding methods are manual metal-arc welding with covered electrodes or gas shielded arc welding. Welding should be undertaken within the heat input range 0.5-2.5 kJ/mm. Maximum interpass temperature is 250°C (482ºF). Preheating or post-weld heat treatment is normally not necessary.
Matching filler metals are recommended in order to obtain a weld metal with optimum corrosion resistance and mechanical properties. For gas-shielded arc welding we recommend Sandvik 22.8.3.L or Sandvik 22.8.3.LSi, developed to give improved welding properties by gas metal arc welding (MIG/MAG).
For manual metal-arc welding, the covered electrode Sandvik 22.9.3.LR is recommended. These filler metals can also be used for welding Sandvik SAF 2205 PM to carbon steels and stainless steels. The covered electrode Sandvik 23.12.2.LR and the welding wire Sandvik 22.15.3.L, both of type AWS 309 Mo with low carbon content, can also be used.
Contact Sandvik for further information regarding welding parameters, post-weld heat treatment etc.
Fabrication
Fabrication of all stainless steels should be done only with tools dedicated to stainless steel materials. Tooling and work surfaces must be thoroughly cleaned before use. These precautions are necessary to avoid cross contamination of stainless steel by easily corroded metals that may discolor the surface of the fabricated product.
Machining
Being a two-phase (austenitic-ferritic) material, Sandvik SAF 2205 PM will present a different tool wear profile from that of single phase steels of types ASTM 304/304L and 316/316L. The cutting speed must therefore be lower than that recommended for ASTM 304/304L and 316/316L. Built-up edges and chipping are to be expected. It is recommended that a tougher insert grade is used than when machining an austenitic stainless steel like, for example ASTM 304L.
Applications
Thanks to its excellent corrosion properties, Sandvik SAF 2205 PM is a highly suitable material for service in environments containing chlorides and hydrogen sulfide. The material is suitable for use for topside and subsea offshore components, such as valve bodies, manifolds, swivels and headers.
The steel is also suitable for use in dilute sulfuric acid solutions and for handling organic acids, e.g. acetic acid and mixtures.
The high strength of Sandvik SAF 2205 PM makes the material an attractive alternative to the austenitic steels in structures subjected to heavy loads.
The good mechanical and corrosion properties make Sandvik SAF 2205 PM an economical choice in many applications by reducing the life cycle cost of equipment.