Esshete 1250 is a fully austenitic chromium-nickel steel with excellent high- temperature strength and good resistance to corrosion in boiler applications. The grade can be used at temperatures up to about 650°C (1200°F), it is easily fabricated and also characterized by:
- High strength in relation to other typical candidate austenitic alloys
- Very good resistance to steam and flue gas atmospheres
- Good structural stability at high temperatures
- Good weldability
Standards
- UNS: S21500
- EN Number: 1.4982
- EN Name: X10CrNiMoMnNbVB15-10-1
Product standards
- ASTM A213
- EN 10216-5
Approvals
- VdTÜV-Werkstoffblatt 520
- PED (Pressure Equipment Directive) 2014/68/EU
Chemical composition (nominal)
C | Si | Mn | P | S | Cr | Ni | Mo | V | Nb | B |
---|---|---|---|---|---|---|---|---|---|---|
0.1 | 0.5 | 6.3 | ≤0.035 | ≤0.015 | 15 | 9.5 | 1.0 | 0.3 | 1.0 | 0.005 |
Applications
The high creep strength of Esshete 1250, combined with its good resistance to steam and flue gas atmospheres, makes it a very suitable material for use in coal-fired boilers. The grade was developed in the United Kingdom in the 1960's, and the bulk of the material has been used in the UK power industry in 500 and 660 MW boilers.
The main application has been superheaters and reheaters operating at 570oC (1058oF), steam pressure 170 bar (superheaters) and 40 bar (reheaters). Typical metal temperature 600–700oC (1112–1292oF), in flue gas temperature 900–1200oC (1652–2192oF). The corrosion environment on the fireside in the UK boilers was historically very aggressive as the British coal has, typically a high chlorine content of up to 0.6%, sulphur at 1–2% and a high ash content of 20%.
Esshete 1250 has also been used successfully in superheaters in biomass boilers, burning various biofuels and producing steam at 580–540oC (1076–1004oF) at 60–200 bars pressure.
Trademark information: Esshete 1250 is a trademark owned by Corus
Corrosion resistance
Air
Good resistance to scaling up to 800°C (1472oF).
Gaseous corrosion
Good resistance to steam and flue gas atmospheres. In service conditions typical of coal-fired boilers, the alloy has a very similar fireside corrosion to alloys of the ASTM 316H type. However, the much increased high-temperature strength gives significantly improved service performance. Fireside corrosion resistance in coal-fired, biomass-fired or coal/biomass co-fired boilers is similar to that of type ASTM 347H. Steam-side corrosion is similar to that of type ASTM 347H.
Bending
Esshete 1250 can be cold bent to narrow bending radii. Heat treatment after cold bending is not normally necessary, but this must be decided after considering the degree of bending and the operating conditions.
If post bending heat treatment is carried out, it should be in the form of solution annealing.
Hot bending is carried out at 1100–850°C (1832–1652°F) and should be followed by solution annealing.
Forms of supply
Seamless tube and pipe in Esshete 1250 is supplied in dimensions up to 260 mm (10.24 in.) outside diameter, in the solution annealed and white-pickled condition or in the bright annealed condition.
Heat treatment
Tubes are delivered in the heat treated 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.
Solution annealing
1050–1150°C (1920–2100°F), 5–20 minutes, rapid cooling in air, gas or water.
Mechanical properties
Proof strength | Tensile strength | Elongation | Hardness | ||
---|---|---|---|---|---|
Rp0.2a) | Rp1.0a) | Rm | Ab) | A2" | HRB |
MPa | MPa | MPa | % | % | |
≥230 | ≥270 | 540–740 | ≥35 | ≥35 | ≤90 |
1 MPa = 1 N/mm2
Proof strength | Tensile strength | Elongation | Hardness | ||
---|---|---|---|---|---|
Rp0.2a) | Rp1.0a) | Rm | Ab) | A2" | HRB |
ksi | ksi | ksi | % | % | |
min. | min. | min. | min. | max. | |
33 | 39 | 78–107 | 35 | 35 | 90 |
a) Rp0.2 and Rp1.0 correspond to 0.2% offset and 1.0% offset yield strengths, respectively.
b) 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 | |
---|---|---|
Rp.02 | Rp1.0 | |
°C | MPa | MPa |
min. | min. | |
50 | 213 | 254 |
100 | 188 | 232 |
150 | 171 | 210 |
200 | 161 | 195 |
250 | 153 | 190 |
300 | 148 | 187 |
350 | 145 | 184 |
400 | 144 | 182 |
450 | 141 | 179 |
500 | 139 | 178 |
550 | 136 | 175 |
600 | 133 | 170 |
650 | 130 | 165 |
700 | 125 | 159 |
Temperature | Proof strength | |
---|---|---|
Rp.02 | Rp1.0 | |
°F | ksi | ksi |
min. | min. | |
100 | 31.2 | 37.4 |
200 | 27.9 | 33.7 |
300 | 25.1 | 30.8 |
400 | 23.1 | 28.6 |
500 | 21.7 | 27.1 |
600 | 21.0 | 26.4 |
700 | 20.8 | 26.2 |
800 | 20.6 | 26.1 |
900 | 20.3 | 25.8 |
1000 | 19.8 | 25.4 |
1100 | 19.3 | 24.7 |
1200 | 18.7 | 23.9 |
1300 | 18.1 | 22.9 |
Creep strength
The creep rupture strength values correspond to values evaluated by Sterling tubes Ltd. The data from creep tests made by Alleima correspond well to the given data.
Temperature | Creep rupture strength, MPa | ||
---|---|---|---|
°C | 10 000 h | 100 000 h | 250 000h |
600 | 241 | 199 | 177 |
610 | 231 | 185 | 158 |
620 | 221 | 167 | 134 |
630 | 210 | 147 | 109* |
640 | 198 | 122 | 90* |
650 | 184 | 100 | 78* |
660 | 167 | 84 | 69* |
670 | 147 | 74 | 52* |
680 | 124 | 66 | 56* |
690 | 102 | 59 | 51* |
700 | 86 | 54 | 46* |
710 | 75 | 49 | 42* |
720 | 67 | 45 | 37* |
730 | 61 | 40* | 32* |
740 | 55 | 36* | - |
750 | 51 | 30* | - |
760 | 46 | - | - |
770 | 42 | - | - |
780 | 38 | - | - |
790 | 34 | - | - |
* Values, which have involved extended stress/time extrapolation
Temperature | Creep rupture strength, ksi | ||
---|---|---|---|
°F | 10 000 h | 100 000 h | 250 000 h |
1100 | 35.2 | 30.7 | 28.8 |
1125 | 33.9 | 27.2 | 23.3 |
1150 | 32.0 | 23.5 | 18.5 |
1175 | 29.6 | 19.5 | 14.6* |
1200 | 26.7 | 15.3 | 11.5* |
1225 | 23.2 | 10.7 | 9.2* |
1250 | 19.1 | 9.8 | 8.3* |
1275 | 14.5 | 8.6 | 7.3* |
1300 | 11.6 | 7.5 | 6.3* |
1325 | 10.0 | 6.4 | 5.3* |
1350 | 8.6 | 5.5 | 4.4* |
1375 | 7.4 | 4.6 | - |
1400 | 6.5 | 3.9 | - |
1425 | 5.7 | - | - |
1450 | 5.1 | - | - |
* Values, which have involved extended stress/time extrapolation
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 |
100 | 14 | 200 | 8 |
200 | 15 | 400 | 9 |
300 | 17 | 600 | 10 |
400 | 19 | 800 | 11 |
500 | 20 | 1000 | 12 |
600 | 22 | 1200 | 13 |
700 | 23 | 1400 | 13.5 |
800 | 24 | 1500 | 14 |
Temperature, °C | J/kg °C | Temperature, °F | Btu/lb °F |
---|---|---|---|
20-100 | 505 | 68-200 | 0.12 |
20-200 | 530 | 68-400 | 0.13 |
20-300 | 540 | 68-600 | 0.13 |
20-400 | 545 | 68-800 | 0.13 |
20-500 | 555 | 68-1000 | 0.13 |
20-600 | 560 | 68-1200 | 0.13 |
20-700 | 565 | 68-1400 | 0.14 |
20-800 | 575 | 68-1600 | 0.14 |
20-900 | 580 | 68-1800 | 0.14 |
20-1000 | 585 | - | - |
1) Mean values in temperature ranges
Temperature, °C | Per °C | Temperature, °F | Per °F |
---|---|---|---|
20-100 | 15 | 68-200 | 8.5 |
20-200 | 16 | 68-400 | 9 |
20-300 | 17 | 68-600 | 9.5 |
20-400 | 18 | 68-800 | 10 |
20-500 | 18.5 | 68-1000 | 10.5 |
20-600 | 19 | 68-1200 | 10.5 |
20-700 | 19 | 68-1400 | 11 |
20-800 | 19.5 | 68-1600 | 11 |
20-900 | 20 | 68-1800 | 11 |
20-1000 | 20 | - | - |
1) Mean values in temperature ranges (x10-6)
Temperature, °C | μΩm | Temperature, °F | μΩin. |
---|---|---|---|
20 | 0.74 | 68 | 29.1 |
100 | 0.80 | 200 | 31.3 |
200 | 0.88 | 400 | 34.6 |
300 | 0.94 | 600 | 37.5 |
400 | 1.00 | 800 | 39.9 |
500 | 1.05 | 1000 | 41.8 |
600 | 1.09 | 1200 | 43.6 |
700 | 1.13 | 1400 | 45.1 |
800 | 1.16 | 1600 | 46.3 |
900 | 1.18 | 1800 | 47.2 |
1000 | 1.20 | - | - |
Temperature, °C | MPa | Temperature, °F | ksi |
---|---|---|---|
20 | 192 | 68 | 27.8 |
100 | 184 | 200 | 26.6 |
200 | 176 | 400 | 25.5 |
300 | 168 | 600 | 24.2 |
400 | 160 | 800 | 22.9 |
500 | 151 | 1000 | 21.5 |
600 | 143 | 1200 | 20.2 |
700 | 135 | 1400 | 18.9 |
800 | 127 | 1600 | 17.7 |
900 | 120 | - | - |
1) (x103)
Structural stability
As in other austenitic stainless steels, sigma phase can be formed after long heat treatment in the range 550–950°C (1022–1742oF). Due to the low chromium content, Esshete 1250 is significantly less sensitive to sigma phase formation than steels of e.g. the ASTM 316 type, according to tests involving ageing for 100000 h.
Welding
The weldability of Esshete 1250 is good. Welding must be carried out without preheating and subsequent heat treatment is normally not required. 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.
For Esshete 1250, heat input of <1.5 kJ/mm and interpass temperature of <150°C (300°F) are recommended.
Recommended filler metals
TIG/GTAW or MIG/GMAW welding
ISO 18274 S Ni 6082 / AWS A5.14 ERNiCr-3 (e.g. Exaton Ni72HP)
MMA/SMAW welding
ISO 14172 E Ni 6182/ AWS A5.11 ENiCrFe-3 (e.g. Exaton Ni71)
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.