Boiler steel 20CrMoVTiB4-10, 1.7729 chromium-molybdenum-vanadium temperature with titanium and boron addition for turbine parts according to PN-EN 10269 norms.
| Standards | Steel Grades | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chemical Composition % | ||||||||||||||||
| C: | Mn: | Si: | P: | S: | Cr: | Mo: | Ni: | V: | Ti: | Al: | Cu: | As: | B: | Sn: | W: | |
| PN | 20HMFTB | |||||||||||||||
| 0.17 - 0.24 | <0.50 | <0.35 | <0.03 | <0.03 | 0.9 - 1.4 | 0.8 - 1.1 | <0.5 | 0.7 - 1.0 | 0.05 - 0.12 | - | - | - | <0.005 | - | - | |
| IS | 20CrMoVTiBH | |||||||||||||||
| 0.17 - 0.24 | <0.50 | <0.35 | <0.03 | <0.03 | 0.9 - 1.4 | 0.8 - 1.1 | <0.5 | 0.7 - 1.0 | 0.05 - 0.12 | - | - | - | - | - | - | |
| EN | 20CrMoVTiB4-10 - 20 CrMoVTiB 4-10 - 20CrMoVTiB5.10 - 1.7729 | |||||||||||||||
| 0.17 - 0.23 | 0.35 - 0.75 | <0.40 | <0.02 | <0.02 | 0.9 - 1.2 | 0.9 - 1.1 | <0.2 | 0.6 - 0.8 | 0.07 - 0.15 | 0.015 0.08 | <0.2 | <0.02 | 0.001 - 0.01 | <0.02 | - | |
| GOST | 20Ch1M1F1TR - 20Kh1M1F1TR - EP182 - 20Х1М1Ф1ТР - ЭП182 | |||||||||||||||
| 0.17 - 0.24 | <0.50 | <0.37 | <0.03 | <0.03 | 0.9 - 1.4 | 0.8 - 1.1 | <0.3 | 0.7 - 1.0 | 0.05 - 0.12 | - | <0.2 | - | <0.005 | - | <0.2 | |
| BS | 681-820 | |||||||||||||||
| 0.17 - 0.23 | 0.35 - 0.75 | 0.10 - 0.35 | <0.02 | <0.02 | 0.9 - 1.2 | 0.9 - 1.1 | <0.2 | 0.6 - 0.8 | 0.07 - 0.15 | <0.08 | <0.2 | <0.02 | 0.001 - 0.01 | <0.02 | - | |
20CrMoVTiB4-10, 1.7729 - boiler steel
20CrMoVTiB4-10 steel belongs to the group of titanium and boron modified pearlitic boiler steels. It is characterized by high relaxation and creep resistance, and low sensitivity to notch action.
Boron addition improves relaxation properties. 20HMFTB steel products are used in a heat-treating state, where after heat treatment they exhibit a sorbitol-peroxide structure with carbides.
This grade is not recommended for use where the yield point exceeds 80 kG/mm2. 20CrMoVTiB4-10 products are used at operating temperatures of 20 ℃ to 550 ℃ for turbine couplings such as screws.
Mechanical properties of 20CrMoVTiB4-10 / 20HMFTB steel
| Strength properties for dimensions < 200 mm | ||
|---|---|---|
| Tensile strength | Rm | > 785 MPa |
| Yield point | Re | 667 - 765 MPa |
| Elongation | A5 | > 15% |
| Contraction | Z | > 45% |
| Impact resistance | KCU2 | > 49 J |
| Hardness | HB | 241 - 269 HB |
Yield limits of thermally improvemed 20CrMoVTiB4-10 bars at varied temperatures
| Re values at particular temperatures | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Temperatures | 20℃ | 50℃ | 100℃ | 150℃ | 200℃ | 250℃ | 300℃ | 350℃ | 400℃ | 450℃ | 500℃ | 550℃ | 600℃ | |
| Yield point | MPa | 647 | 662 | 657 | 637 | 613 | 598 | 588 | 588 | 583 | 569 | 534 | 490 | 427 |
Creep limit R1 and creep strength R2 of 1.7729, 20CrMoVTiB4-10 steel in tempered condition
| Properties specified in the MPa | Approximate properties at temperatures | ||||||
|---|---|---|---|---|---|---|---|
| 520℃ | 530℃ | 540℃ | 550℃ | 560℃ | 570℃ | ||
| Creep limit | R1/10000 | 302 | 287 | 273 | 259 | 248 | 237 |
| R1/100000 | 243 | 233 | 226 | 218 | 210 | 203 | |
| Creep resistance | Rz/10000 | 329 | 314 | 298 | 281 | 267 | 252 |
| Rz/100000 | 279 | 265 | 252 | 240 | 229 | 220 | |
Heat treatment of 20CrMoVTiB4-10, 1.7729 steel
| Heat treatment | ||
|---|---|---|
| Heat treatment type | Cooling type | Temperatures |
| Normalization | - | 1050 - 1100℃ |
| Hardening | in air | 950 - 1000℃ |
| in oil | 980 - 1050℃ | |
| Tempering | in air | 660 - 730℃ |
Welding, cutting and gouging of 20CrMoVTiB4-10, 1.7729 steel
Steel 20CrMoVTiB4-10, 1.7729 should not be welded. The exceptional joining process is bonding, which, despite being limited, can be frictional or electrically resistive with proper bonding and heat treatment parameters.
Materials can be cut with propane-butane-oxygen flame, acetylene-oxygen flame, or plasma arc. Before you start cutting, you must preheat to:
<50mm
- 350 - 400℃ with dimensions >50mm
In the case of gas cutting, the temperature of the lower limits should be chosen. When performing plasma cutting, use the heating temperatures of the upper limits of the range given above. After cutting, the product should be slowly cooled to ambient temperature together with the oven, hot sand or asbestos mat.
In addition, steel can be arc-air electrode deseamed or flame gouged. Before the process, the products must be heated to the cutting temperature, and also cooled down to ambient temperature. After the process, appropriate thermal processes must be performed, however, this does not guarantee the possibility of cracking on the grooved surfaces, especially in arc-air electrode deseaming.
In the 20CrMoVTiB4-10 grade Virgamet provides:
List of equivalents and other determinations of 20HMFTB steel:
20CrMoVTiBH, 20CrMoVTiB4-10, 20 CrMoVTiB 4-10, 20CrMoVTiB5.10, 25CrMoVB6.11, 1.7729, 20Ch1M1F1TR, 20Kh1M1F1TR, EP182, 20Х1М1Ф1ТР, ЭП182, BS 681-820