Sanicro® 41, commonly known as Alloy 825, is an austenitic corrosion resistant Ni-Fe-Cr alloy. It is characterized by:
- Excellent resistance to stress corrosion cracking in chloride and sour (H2S/Cl-) environments
- Excellent resistance to attack by acidic media such as sulfuric and phosphoric acid
- Better resistance to pitting and crevice corrosion compared to steels of the ASTM 316 type
- Good weldability
Standards
- ASTM: 825
- UNS: N08825
- W.Nr.: 2.4858
- DIN: NiCr 21 Mo
- BS: NA14
Product standards
Suitable for production of flanges etc. according to ASTM B564
Certificates
Status according to EN 10 204 3.1
Chemical composition (nominal) %
| C | Si | Mn | P | S | Cr | Ni | Mo | Others |
|---|---|---|---|---|---|---|---|---|
| ≤0.05 | ≤0.5 | 0.8 | ≤0.025 | ≤0.015 | 20 | 38.5 | 2.6 | Ti=0.7 Cu=1.7 Al=0.1 |
Applications
Sanicro® 41 has good resistance to general and localized corrosion under diverse conditions. Applications can be found in chemical processing, oil and gas production, acid production, pickling operations and corrosive environments containing sulfuric acid, phosphoric acid, sulfur containing gases, oil wells and sea water.
| Industrial categories | Typical applications |
|---|---|
| Chemical industry | Flanges |
| Food industry | Valves and discs |
| Petrochemical industry | Fittings |
| Pulp and paper industry | Couplings |
| Pickling equipment | Rings and seals |
| Oil & Gas industry | Bolts and nuts |
| Nuclear fuel reprocessing | Shafts |
| Forgings | |
| Piping | |
| Pumps | |
| Tanks |
Corrosion resistance
General corrosion
Sanicro® 41 possesses excellent resistance to corrosion. The material is clearly superior to standard molybdenum-alloyed steels such as AISI 316L, particularly when exposed to non-oxidizing media, such as sulfuric or phosphoric acid. The resistance to highly oxidizing agents, such as nitric acid, is also satisfactory.
Pitting and crevice corrosion
The resistance of Sanicro® 41 to pitting and crevice corrosion is superior to that of AISI 316 - a result of the higher chromium and molybdenum contents in the material.
Stress corrosion cracking
The high nickel content of the material promotes excellent resistance to stress corrosion cracking induced by both chlorides and alkalis. Sanicro® 41 has shown excellent resistant to stress corrosion cracking in sour environments.
Intergranular corrosion
Since the material is titanium-stabilized, the risk of intergranular corrosion is minimized.
For further information on corrosion resistance of Sanicro® 41, please see the datasheet - Seamless tube and pipe Sanicro® 41. The data should be considered in the knowledge that it may not be applicable for thick sections, such as forgings.
Forms of supply
Sizes and tolerances
Round-cornered square, as well as round billets, are produced in a wide range of sizes according to the following tables. Larger sizes offered on request.
Surface conditions
Square billets
Unground, spot ground or fully ground condition.
Round billets
Peel turned or black condition.
| Size | Tolerance | Length |
|---|---|---|
| mm | mm | m |
| 80 | +/-2 | 4 - 6.3 |
| 100, 114, 126, 140, 150 | +/-3 | 4 - 6.3 |
| 160, 180, 195, 200 | +/-4 | 4 - 6.3 |
| >200 - 350 | +/-5 | 3 - 5.3 |
Sizes and tolerances apply to the rolled/forged condition.
| Size | Tolerance | Length |
|---|---|---|
| mm | mm | m |
| 75 - 200 (5 mm interval) | +/-1 | max 10 |
| >200 - 450 | +/-3 | 3 - 8 |
| Size | Tolerance | Length |
|---|---|---|
| mm | mm | m |
| 77 - 112 (5 mm interval) | +/-2 | max 10 |
| 124, 134 | +/-2 | max 10 |
| 127, 147, 157 | +/-2 | max 10 |
| 142, 152, 163 | +/-2 | max 10 |
| 168, 178, 188 | +/-2 | max 10 |
| 183, 193 | +/-2 | max 10 |
Other products
- Seamless tube and pipe
- Hollow bars
Heat treatment
Billets are delivered in hot worked condition. The following heat treatment is recommended for finished products.
Solution annealing
930-980°C (1700-1800°F) followed by quenching in water.
Mechanical properties
Sanicro® 41 conforms to the required mechanical properties according to specification ASTM B564. Testing is performed on separately solution annealed and quenched test piece.
At 20 oC
|
Proof strength
|
Tensile strength
|
Elongation
|
|---|---|---|
| Rp0.21) | Rm | A |
| MPa | MPa | % |
|
≥241
|
≥586
|
≥30
|
At 68 oF
|
Proof strength
|
Tensile strength
|
Elongation
|
|---|---|---|
| Rp0.21) | Rm | A |
| ksi | ksi | % |
|
≥35
|
≥85
|
≥30
|
1) Corresponds to 0.2 % offset yield strength
At high temperatures
Fig. 1 shows indicative values for tensile strength properties of Sanicro 41 at high temperatures.
Physical properties
| Temperature, °C | J/(Kg °C) | Temperature, °F | Btu/(lb °F) |
|---|---|---|---|
| 20 | 440 | 68 | 0.11 |
1) typical value
| Temperature, °C | W/(kg oC) | Temperature, °F | Btu/(ft h oF) |
|---|---|---|---|
| 20 | 11 | 68 | 6 |
1) typical value
| Temperature, °C | Per °C | Temperature, °F | Per °F |
|---|---|---|---|
| 30-100 | 14.2 | 86-200 | 7.9 |
| 30-200 | 14.6 | 86-400 | 8.1 |
| 30-300 | 14.9 | 86-600 | 8.3 |
| 30-400 | 15.1 | 86-800 | 8.4 |
| 30-500 | 15.3 | 86-1000 | 8.5 |
1) typical values (x10-6)
Hot working
The hot forming range for Sanicro® 41 is 900-1175°C (1740-2150°F), followed by quenching in water. Subsequent heat treatment should be carried out in accordance with the recommendations given for heat treatment.
Welding
The weldability of Sanicro® 41 is good. Suitable methods of fusion welding are manual metal-arc welding (MMA/SMAW) and gas-shielded arc welding, with the TIG/GTAW method as first choice.
Since the material has low thermal conductivity and high thermal expansion. Welding plans should therefore be carefully selected in advance, so that distortions of the welded joint are minimized. If residual stresses are a concern, solution annealing can be performed after welding.
For Sanicro® 41, heat-input of <1.0 kJ/mm and interpass temperature of <100°C (210°F) are recommended. A string bead welding technique should be used.
Recommended filler metals
TIG/GTAW or MIG/GMAW welding
ISO 18274 S Ni 8065/AWS A5.14 ERNiFeCr-1 (e.g. Exaton Sanicro 41 Cu)
ISO 14343 S 27 31 4 Cu L/AWS A5.9 ER383 (e.g. Exaton 27.31.4.LCu)
MMA/SMAW welding
ISO 14172 E Ni 8025, E Ni 8165
ISO 3581 E 27 31 4 Cu L R/AWS A5.4 E383-16 (e.g. Exaton 27.31.4.LCuR)
Machining
Machining Sanicro® 41, as with other stainless steels, requires an adjustment to tooling data and machining method, in order to achieve satisfactory results. Compared to Sanmac® 316/316L, the cutting speed must be reduced by approximately 55-60%, when turning Sanicro® 41 with coated, cemented carbide tools. Much the same applies to other operations. Feeds should be reduced by approximately 10-15% and with care.
Detailed recommendations for the choice of tools and cutting data are provided in the data sheet for Sanmac® 316/316L.
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.