20H12VNMF (EP428, 25P2VNMF)
highly loaded parts for steam and gas turbines, long operating at temperatures up to 600 ° C .; martensitic steel grade
Classification
| Country |
Section |
Category |
| CIS, Russia, Ukraine |
Heat resistant steels and alloys |
Heat resistant high alloy steel |
Chemical composition
| Standard |
Fe, % |
Si, % |
Mn, % |
Cr, % |
Ni, % |
V, % |
P, % |
C, % |
S, % |
Mo, % |
W, % |
|---|
| GOST 5632-72 |
82.715–86.98 |
< 0.6 |
0.5–0.9 |
10.5–12.5 |
0.5–0.9 |
0.15–0.3 |
< 0.03 |
0.17–0.23 |
< 0.025 |
0.5–0.7 |
0.7–1.1 |
Information on suppliers
Physical characteristics
| Temperature, °C |
$$E\cdot 10^{9}$$, $$MPa$$ |
$$\alpha\cdot 10^{6}$$, $$K^{-1}$$ |
$$\varkappa$$, $$\frac{W}{m\cdot K}$$ |
$$\rho$$, $$\frac{kg}{m^3}$$ |
|---|
| 20 |
212 |
|
|
7850 |
| 100 |
207 |
10.6 |
25 |
7830 |
| 200 |
202 |
10.9 |
25 |
7800 |
| 300 |
196 |
11.2 |
26 |
7780 |
| 400 |
190 |
11.4 |
26 |
7760 |
| 500 |
181 |
11.7 |
27 |
7730 |
| 600 |
167 |
11.9 |
27 |
7700 |
| 700 |
|
12 |
|
7670 |
| 800 |
|
12.1 |
|
|
Mechanical properties at 20 °C
| Rolling |
Standard |
Size, mm |
Tension |
Classifiers |
$$\sigma _{U}$$, $$MPa$$ |
$$\sigma_{P}$$, $$MPa$$ |
$$\epsilon_L$$, % |
$$\psi$$, % |
$$KCU\cdot 10^{3}$$, $$\frac{J}{m^2}$$ |
Treatment |
|---|
| Rod |
GOST 5949-75 |
|
|
|
740 |
590 |
15 |
50 |
590 |
Hardening of 1010-1060 ° C, the oil, leave 660-670 ° C, air |
| Rod |
GOST 18968-73 |
|
|
|
740 |
590–755 |
15 |
50 |
590 |
Normalized and tempered |
Brinell hardness number
| Rolling |
Standard |
Classifiers |
Value, HBW |
| Rod |
GOST 5949-75 |
annealing |
229 |
| Rod |
GOST 18968-73 |
normalization, average vacation |
229–269 |
Technological Properties
| Weldability |
|---|
| Difficult to weld |
Critical point temperatures
| Ac1, K |
Ac3(Acm), K |
|---|
| 800 |
860 |
Analogues
Standards
Description of chemical elements
| Element |
Units of measurement |
Description |
| Fe |
% |
Iron |
| Si |
% |
Silicon |
| Mn |
% |
Manganese |
| Cr |
% |
Chrome |
| Ni |
% |
Nickel |
| V |
% |
Vanadium |
| P |
% |
Phosphorus |
| C |
% |
Carbon |
| S |
% |
Sulfur |
| Mo |
% |
Molybdenum |
| W |
% |
Tungsten |
Description of physical characteristics
| Parameter |
Units of measurement |
Description |
| $$E\cdot 10^{9}$$ |
$$MPa$$ |
Elastic modulus |
| $$\alpha\cdot 10^{6}$$ |
$$K^{-1}$$ |
Coefficient of thermal (linear) expansion (range 20°C–T) |
| $$\varkappa$$ |
$$\frac{W}{m\cdot K}$$ |
Coefficient of thermal conductivity (the heat capacity of the material) |
| $$\rho$$ |
$$\frac{kg}{m^3}$$ |
The density of the material |
Description of mechanical properties
| Parameter |
Units of measurement |
Description |
| $$\sigma _{U}$$ |
$$MPa$$ |
Ultimate tensile strength |
| $$\sigma_{P}$$ |
$$MPa$$ |
Proportionality limit |
| $$\epsilon_L$$ |
% |
Elongation at break (longitudinal) |
| $$\psi$$ |
% |
Reduction in cross section on fracture |
| $$KCU\cdot 10^{3}$$ |
$$\frac{J}{m^2}$$ |
Impact toughness |
Designation of types of weldability
| Parameter |
Units of measurement |
Description |
| no limits |
|
Welding is performed without heating and without subsequent heat treatment |
| Boundedly welded |
|
Welding is possible with heating up to 100–120 °C and subsequent heat treatment |
| Difficult to weld |
|
For obtaining quality welded joints, additional operations are required: heating up to 200–300 °C for welding, heat treatment after welding — annealing |
| Not applicable for welded structures |
|
|
Description of temperatures of critical points
| Parameter |
Units of measurement |
Description |
| Ac1 |
K |
|
| Ac3(Acm) |
K |
|