Alleima® 7RE10 is an austenitic, stainless chromium-nickel steel of the 25/20 type, suitable for high-temperature applications. The grade is characterized by:
- Good resistance to carburization, sulphidation, and oxidation combined with moderate creep strength and structural stability.
- A maximum service temperature in air of 1100°C (2010°F).
Standards
- ASTM: TP310S, TP310H
- UNS: S31008, S31009
- EN Number: 1.4845
- EN Name: X 8 CrNi 25-21
- W.Nr.: 1.4845
- DIN: X 12 CrNi 25 21
- SS: 2361
- AFNOR: Z 12 CN 25.20
Product standards
Seamless tube and pipe
- ASTM A213, A312
- EN 10297-2
- Stahl-Eisen-Werkstoffblatt 470
- SS 14 23 61
- NFA 49-117
Chemical composition (nominal)
| C | Si | Mn | P | S | Cr | Ni |
|---|---|---|---|---|---|---|
| 0.06 | ≤0.75 | 1.5 | ≤0.030 | ≤0.015 | 24.5 | 21 |
Applications
The good, general high temperature corrosion resistance of Alleima® 7RE10 makes it suitable for a wide range of applications:
- Furnace tubes
- Recuperators
- Muffle tubes in continuous wire annealing furnaces
- Thermocouple protection tubes
- Radiant tubes
- Tube hangers in petroleum and steam boilers
- Burners
Corrosion resistance
Alleima® 7RE10 has very good resistance to oxidation and sulphidation. It can be used in:
- Air up to 1100°C (2010°F)
- Sulphur-containing atmospheres up to 650-1050°C (1200-1920°F), depending on service conditions. Factors to consider are whether the atmosphere is oxidizing or reducing and whether impurities such as sodium and vanadium are present
The high chromium content of Alleima® 7RE10 makes the material resistant to oxidizing aqueous solutions. Alleima® 7RE10 also has better resistance to chloride induced stress corrosion cracking than lower alloyed steels of type ASTM 304 and 316.
Alleima® 7RE10 has good resistance in cyanide melts and neutral salts melts at high temperature. The material is insensitive to "green rot" attack.
Bending
Annealing after cold bending is not normally necessary, but this should be reviewed depending on the degree of bending and the operating conditions.
Heat treatment, if any, should take the form of stress relieving or solution annealing. See under "Heat treatment". Solution annealing is recommended for tubes used at temperatures above 750°C (1380°F), and when the highest possible creep strength is required in the bent tube.
Hot bending is carried out at 1100-850°C (2010-1560°F) and should be followed by solution annealing.
Forms of supply
Seamless tube and pipe - finishes and dimensions
Seamless tube and pipe in Alleima® 7RE10 is supplied in dimensions up to 260 mm outside diameter, in the solution annealed and white-pickled condition or in the bright annealed condition.
Stock sizes
Alleima® 7RE10 is stocked in sizes ranging from 13.5 mm to 168.28 mm (6") outside diameter. OD below 30.0 mm supplied as ASTM standard TP310S/TP310H
Additional data concerning sizes and finishes is available on request from your nearest Alleima office.
Heat treatment
Tubes are generally delivered in the solution annealed condition. If another heat treatment is needed after further processing the following is recommended:
Stress relieving
850-950°C (1560-1740°F), 10-15 minutes, cooling in air.
The temperature should not be allowed to fall below 850°C (1560°F), because of the risk of sensitization.
Solution annealing
1000-1150°C (1830-2100°F), 5-20 minutes, rapid cooling in air or water.
Mechanical properties
At 20°C
| Proof strength | Tensile strength | Elong. | Hardness | ||
|---|---|---|---|---|---|
| Rp0.21) | Rp1.01) | Rm | A2) | A2" | HRB |
| MPa | MPa | MPa | % | % | |
| ≥220 | ≥250 | 530-750 | ≥35 | ≥35 | ≤90 |
At 68°F
| Proof strength | Tensile strength | Elong. | Hardness | ||
|---|---|---|---|---|---|
| Rp0.21) | Rp1.01) | Rm | A2) | A2" | HRB |
| ksi | ksi | ksi | % | % | |
| ≥32 | ≥35 | 77-109 | ≥35 | ≥35 | ≤90 |
1 MPa = 1 N/mm2
1) Rp0.2 and Rp1.0 correspond to 0.2% offset and 1.0% offset yield strength, respectively.
2) Based on L0 = 5.65 √S0 where L0 is the original gauge length and S0 the original cross-sectional area.
At high temperatures
| Temperature | Proof strength | |
|---|---|---|
| °C | Rp0.2 | Rp1.0 |
| MPa | MPa | |
| min | min | |
| 50 | 213 | 238 |
| 100 | 192 | 217 |
| 150 | 176 | 201 |
| 200 | 161 | 186 |
| 250 | 150 | 175 |
| 300 | 141 | 166 |
| 350 | 134 | 159 |
| 400 | 129 | 154 |
| 450 | 125 | 150 |
| 500 | 123 | 148 |
| 550 | 121 | 146 |
| Temperature | Proof strength | |
|---|---|---|
| °F | Rp0.2 | Rp1.0 |
| ksi | ksi | |
| min | min | |
| 200 | 28.3 | 31.9 |
| 300 | 25.6 | 28.9 |
| 400 | 23.2 | 26.8 |
| 500 | 21.4 | 25.1 |
| 600 | 20.1 | 23.8 |
| 700 | 19.1 | 22.8 |
| 800 | 18.4 | 22.0 |
| 900 | 17.9 | 21.6 |
| 1000 | 17.6 | 21.2 |
Creep strength
Creep rupture strength 10 000 h, average values
| Temperature, °C | MPa | Temperature, °F | ksi |
|---|---|---|---|
| 525 | 155 | 1000 | 20.9 |
| 550 | 133 | 1050 | 18.0 |
| 575 | 113 | 1100 | 14.6 |
| 600 | 96 | 1150 | 12.0 |
| 625 | 81 | 1200 | 9.9 |
| 650 | 68 | 1250 | 7.8 |
| 675 | 55 | 1300 | 6.2 |
| 700 | 44 | 1350 | 5.0 |
| 725 | 36 | 1400 | 4.1 |
| 750 | 30 | 1450 | 3.3 |
| 775 | 25 | 1500 | 2.8 |
| 800 | 21 | 1550 | 2.3 |
| 825 | 18 | 1600 | 1.8 |
| 850 | 15 | 1650 | 1.5 |
| 875 | 12 | 1700 | 1.1 |
| 900 | 10 | 1750 | 0.8 |
| 925 | 8 | ||
| 950 | 6 |
Values for creep strain 1% can be given on request.
Creep rupture strength 100 000 h, average values
| Temperature, °C | MPa | Temperature, °F | ksi |
|---|---|---|---|
| 525 | 105 | 1000 | 13.8 |
| 550 | 85 | 1050 | 10.7 |
| 575 | 68 | 1100 | 8.6 |
| 600 | 56 | 1150 | 6.7 |
| 625 | 45 | 1200 | 5.3 |
| 650 | 36 | 1250 | 4.1 |
| 675 | 29 | 1300 | 3.4 |
| 700 | 24 | 1350 | 2.8 |
| 725 | 20 | 1400 | 2.3 |
| 750 | 17 | 1450 | 1.8 |
| 775 | 14 | 1500 | 1.4 |
| 800 | 11 | 1550 | 1.1 |
| 825 | 9 | 1600 | 0.8 |
| 850 | 7 | 1650 | 0.6 |
| 875 | 5 | 1700 | 0.5 |
| 900 | 4 | 1750 | 0.4 |
| 925 | 4 | ||
| 950 | 3 |
Values for creep strain 1% can be given on request.
Physical properties
Density: 7.9 g/cm3, 0.29 lb/in3
| Temperature, °C | W/m °C | Temperature, °F | Btu/ft h °F |
|---|---|---|---|
| 20 | 13 | 68 | 7.5 |
| 100 | 15 | 200 | 8.5 |
| 200 | 17 | 400 | 10 |
| 300 | 19 | 600 | 11.5 |
| 400 | 21 | 800 | 12.5 |
| 500 | 23 | 100 | 13.5 |
| 600 | 25 | 1200 | 14.5 |
| 700 | 26 | 1300 | 15 |
| Temperature, °C | J/kg °C | Temperature, °F | Btu/lb °F |
|---|---|---|---|
| 20 | 470 | 68 | 0.11 |
| 100 | 495 | 200 | 0.12 |
| 200 | 530 | 400 | 0.13 |
| 300 | 555 | 600 | 0.13 |
| 400 | 580 | 800 | 0.14 |
| 500 | 600 | 1000 | 0.15 |
| 600 | 615 | 1200 | 0.15 |
| 700 | 630 | 1300 | 0.15 |
| Temperature, °C | Per °C | Temperature, °F | Per °F |
|---|---|---|---|
| 20-100 | 15.0 | 68-200 | 8.5 |
| 20-200 | 15.5 | 68-400 | 8.5 |
| 20-300 | 16.0 | 68-600 | 9.0 |
| 20-400 | 16.5 | 68-800 | 9.5 |
| 20-500 | 17.0 | 68-1000 | 9.5 |
| 20-600 | 17.5 | 68-1200 | 9.5 |
| 20-700 | 18.0 | 68-1400 | 10.0 |
| 20-800 | 18.5 | 68-600 | 10.0 |
| 20-900 | 19.0 | 68-1800 | 10.5 |
| 20-1000 | 19.0 |
| Temperature, °C | MPa | Temperature, °F | ksi |
|---|---|---|---|
| 20 | 195 | 68 | 28.3 |
| 100 | 190 | 200 | 27.6 |
| 200 | 182 | 400 | 26.4 |
| 300 | 174 | 600 | 25.1 |
| 400 | 166 | 800 | 23.8 |
| 500 | 158 | 1000 | 22.5 |
Structural stability
Like other austenitic stainless steels, Alleima® 7RE10 has better structural stability than high alloyed ferritic steels. At temperatures between 800 and 900°C (1470-1650°F), however, the structural stability will be slightly impaired. For service in this temperature range, we recommend the use of Sanicro® 31HT, which has better structural stability.
Welding
The weldability of Alleima® 7RE10 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.
In common with all fully austenitic stainless steels, Alleima® 7RE10 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.
Welding of fully austenitic stainless steel can entail the risk of hot cracking in the welded joints, particularly under high constraint.
For Alleima 7RE10, 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 14343 S 25 20 / AWS A5.9 ER310 (e.g. Exaton 25.20.C)
MMA/SMAW welding
ISO 3581 E 25 20 B / AWS A5.4 E310-15 (e.g. Exaton 25.20.B)
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.