21CrMoV5-7, 1.7709, 21CrMoV5-11, 1.8070 boiler steel designed for use at elevated temperatures up to 550 ℃ according to PN-75 / H-84024, EN 10269, ISO TR 4956, DIN 17240-76.
| Standards | Steel Grades | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Chemical Composition % | |||||||||||
| C: | Mn: | Si: | P: | S: | Cr: | Ni: | Mo: | V: | Al: | Cu: | |
| PN | 21HMF | ||||||||||
| 0.17 - 0.25 | 0.3 - 0.5 | 0.3 - 0.6 | <0.035 | <0.035 | 1.2 - 1.5 | <0.6 | 1.0 - 1.2 | 0.25 - 0.35 | - | - | |
| EN / DIN | 21CrMoV5-7 - 21 CrMoV 5-7 - 1.7709 | ||||||||||
| 0.17 - 0.25 | 0.4 - 0.8 | <0.4 | <0.025 | <0.030 | 1.2 - 1.5 | <0.6 | 0.55 - 0.80 | 0.20 - 0.35 | <0.3 | - | |
| GOST | 25Ch1M1F - 21Kh1M1F - 25Х1М1Ф | ||||||||||
| 0.22 - 0.29 | 0.4 - 0.7 | 0.17 - 0.37 | <0.030 | <0.025 | 1.5 - 1.8 | <0.3 | 0.25 - 0.35 | 0.15 - 0.30 | - | <0.2 | |
| DIN | 21CrMoV5-11 - 21 CrMoV 5-11 - 1.8070 | ||||||||||
| 0.17 - 0.25 | 0.3 - 0.6 | 0.30 - 0.60 | <0.035 | <0.035 | 1.2 - 1.5 | <0.6 | 1.0 - 1.2 | 0.25 - 0.35 | - | - | |
| AFNOR | 20CDV5-07 - 20 CDV 5-07 - 20CDV5.07 | ||||||||||
| 0.17 - 0.24 | 0.3 - 0.6 | <0.5 | <0.015 | <0.015 | 1.1 - 1.5 | <0.5 | 0.5 - 0.8 | 0.15 - 0.35 | - | - | |
| MSZ | MCrMoV | ||||||||||
| 0.17 - 0.25 | 0.5 - 0.8 | 0.17 - 0.37 | <0.035 | <0.035 | 1.2 - 1.5 | 0.3 - 0.6 | 0.8 - 1.0 | 0.30 - 0.45 | - | <0.3 | |
21CrMoV5-7, 1.7709 - description and application
21HMF alloy structural steel and its 21CrMoV5-7 / (i.e) 21CrMoV5-11 replacement alloys belong to the group of high temperature boiler steels for energy industries. They are used in the production of components/subassemblies for the power industry, working at the temperatures up to 550 oC for small parts and for large forgings. The main applications of these grades of steel are rotors of steam turbines, rotor blades, shaft forgings, reservoirs and covers for up to 550 ℃ temperatures, nuts, tubes for high temperatures up to 540 ℃.
The mechanical properties of 21CrMoV5-7/1.7709 mm +QT up to 160 mm
- Tensile strength, Rm = 700 - 850 MPa
- Yield point, Re > 550 MPa
- Elongation, A > 16%
- Contraction, Z > 60%
- Notch toughness, KV20℃ > 63 J
Yield point at individual temperatures
- Re przy 200℃ = 500 MPa
- Re przy 300℃ = 460 MPa
- Re przy 400℃ = 412 MPa
- Re przy 500℃ = 334 MPa
- Re przy 550℃ = 275 MPa
Permissible temperature of application of steel in hydrogen containing environments depends on its partial pressure 21CrMoV5-11
| Temperatures ℃ | 600 | 380 | 330 | 325 | 320 | 310 | 300 | 280 |
|---|---|---|---|---|---|---|---|---|
| Partial pressure kG/cm2 | 1 | 100 | 150 | 200 | 300 | 400 | 500 | 800 |
Creep limit and creep resistance of 21HMF / 21CrMoV5-11 / 1.8070 according to tests on rotors at 550 ℃
| Time, h | 10 | 102 | 103 | 104 | 105 |
|---|---|---|---|---|---|
| Creep limit, R0,1 (N/mm2) | ~200 | ~158 | ~110 | ~64 | - |
| Creep resistance, Rz (N/mm2) | ~310 | ~280 | ~240 | ~195 | ~123 |
Thermal treatment of 21CrMoV5-7, 1.7709
- Softening at 650 °C with slow cooling
- Slow relief annealing at 530 °C at furnace to at least 200
- Normalizing at 950 - 980℃ with cooling in calm air
- Hardening at 930 - 950℃ in water, 940 - 960℃ in oil
- Tempering at a temperature of 650 ° c in the air for many hours depending on the size of the material
In the above mentioned grades the company provides:
- Hot rolled bars, peeled bars, and drawn bars 21CrMoV5-7, 1.7707, 21CrMoV5-11, 1.8070, 21HMF
- Forged bars and forgings 21CrMoV5-7, 1.7707, 21CrMoV5-11, 1.8070, 21HMF
- Flanges 21HMF, 21CrMoV5-7, 21CrMoV5-11, 1.7707, 1.8070
Other alternatives and equivalents of 21HMF:
21 CrMoV 5-7, 21 CrMoV 57, 21CrMoV5-7, 1.7707, 7707, 21CrMoV5.7, 21CrMoV5-11, 21 CrMoV 5-11, 1.8070, 21 CrMoV 5.11, 20CDV5.08, 20CDV5-08, 20 CDV 5-08, CSN 15236, CSN 15335, MCrMoV2, MCrMoV, A404-68 Grade F24, BS 1506, 25Ch1M1F, 21Kh1M1F, 25Х1М1Ф