Designation
| Name |
The value |
| Designation GOST Cyrillic |
25Х17Н2Б |
| Designation GOST Latin |
25X17H2B |
| Transliteration |
25H17N2B |
| By chemical elements |
25Cr17Н2Nb |
Description
25Х17Н2Б steel is used: for the production of long products, forgings, die forgings; billets of steel products for the manufacture of pipe fittings that are installed at hazardous production facilities.
Standards
| Name |
Code |
Standards |
| Processing of metals by pressure. Forgings |
В03 |
ST ЦКБА 010-2004 |
| Thermal and thermochemical treatment of metals |
В04 |
ST ЦКБА 016-2005 |
| Bars and shapes |
В32 |
TU 14-1-1062-74 |
| Sheets and strips |
В33 |
TU 14-1-3572-83 |
Chemical composition
| Standard |
C |
S |
P |
Mn |
Cr |
Si |
Ni |
Fe |
Cu |
Nb |
| TU 14-1-1062-74 |
0.22-0.28 |
≤0.015 |
≤0.02 |
0.3-0.7 |
16.3-17.7 |
0.3-0.7 |
2.3-2.8 |
Rest |
≤0.25 |
0.05-0.1 |
Fe is the basis.
According to TU 14-1-1062-74, the chemical composition is given for steel grade 25Х17Н2Б-Ш. The following deviations from the established norms of chemical composition are allowed: carbon +0.010%, chromium ± 0.20%, nickel ± 0.10%.
Mechanical properties
| Section, mm |
t отпуска, °C |
sT|s0,2, MPa |
σU, MPa |
d5, % |
y, % |
KCU, kJ/m2 |
HB, MPa |
HRC |
| Blank pieces of pipe fittings according to ST CKBA 016-2005. Quenching in oil with 1100-1120 °C + cold Treatment at -70 °C (exposure 2 hours) + Vacation, air cooling |
| ≤60 |
200-320 |
≥1176 |
≥1470 |
≥8 |
≥45 |
≥392 |
≥415 |
≥44.5 |
| Blank pieces of pipe fittings according to ST CKBA 016-2005. Quenching in oil with 950-970 °C + Vacation, air cooling |
| ≤60 |
630-650 |
≥784 |
≥980 |
≥12 |
≥50 |
≥490 |
≥285 |
≥31 |
| Bars and stripes on the other 14-1-1062-74. Quenching in oil with 1100 °C + cold treatment at -70 °C 2 hours + Vacation at 250-320 °C (2 hours). Longitudinal samples with allowance for grinding |
| ≤250 |
- |
≥1175 |
≥1470 |
≥8 |
≥45 |
≥490 |
≥302 |
- |
Description mechanical marks
| Name |
Description |
| sT|s0,2 |
Yield strength or limit of proportionality with a tolerance for residual deformation of 0.2% |
| σU |
Limit short-term strength |
| d5 |
Elongation after rupture |
| y |
The relative narrowing |
| KCU |
Toughness |
| HB |
Brinell hardness number |
| HRC |
Rockwell hardness (indenter diamond spheroconical) |
Technological properties
| Name |
The value |
| Features of heat treatment |
To obtain characteristic values of mechanical properties and hardness set ST CKBA 010 and to achieve maximum corrosion resistance, parts (workpiece) valves shall be subjected to hardening and tempering. Parts included in friction and sealing shutter valves, can be subjected to surface hardening with heating by high frequency currents (HFC) with the aim of improving hardness while maintaining high mechanical properties in the core part. Surface hardening with heating HDTV applies to parts of thickness (diameter) of not less than 15 mm and is made only after a preliminary heat treatment to improve hardness of 31 HRC. |
| Machinability |
To improve the machinability and the hardness HB ≤ 293 of the workpiece is subjected to two-stage annealing: step 1 870-890 °C (exposure 4 h), cooling oven with a speed of 30-40 °C/h to 400 °C, then - on the air; stage 2 650-670 (exposure 4 h), cooling oven with a speed of 30-40 °C/h to 500 °C, then on air. |
