18H2N4MA (18H2N4VA)
It is used for critical parts to the cat. high strength requirements are imposed.
The carburized and quenched and tempered condition is applied to critical parts, which are requirements of high strength, toughness and wear resistance, as well as for parts subject to high vibration and dynamic loads. Steel can be applied at temperatures from -70 to +450 ° C.
Classification
| Country |
Section |
Category |
| CIS, Russia, Ukraine |
Structural steel |
Alloyed structural steel |
Chemical composition
| Standard |
Fe, % |
Si, % |
Mn, % |
Cr, % |
Ti, % |
Cu, % |
Ni, % |
P, % |
C, % |
S, % |
Mo, % |
|---|
| GOST 4543-71 |
92.02–93.79 |
0.17–0.37 |
0.25–0.55 |
1.35–1.65 |
< 0.06 |
< 0.3 |
4–4.4 |
< 0.025 |
0.14–0.2 |
< 0.025 |
0.3–0.4 |
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 |
200 |
|
|
7950 |
| 100 |
165 |
11.7 |
36 |
7930 |
| 200 |
141 |
12.2 |
36 |
7900 |
| 300 |
|
12.7 |
35 |
7860 |
| 400 |
139 |
13.1 |
35 |
7830 |
| 500 |
|
13.5 |
34 |
7800 |
| 600 |
|
13.9 |
33 |
7760 |
| 700 |
|
|
32 |
|
| 800 |
|
|
30 |
|
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 4543-71 |
15 |
|
|
1130 |
835 |
12 |
50 |
980 |
Hardening and tempering |
Brinell hardness number
| Rolling |
Standard |
Classifiers |
Value, HBW |
| Alloy |
GOST 4543-71 |
annealing |
269 |
Technological Properties
| Weldability |
Flake Susceptibility |
Propensity to temper brittleness |
|---|
| Difficult to weld |
sensitive |
not inclined |
Critical point temperatures
| Ac1, K |
Ac3(Acm), K |
Ar3(Arcm), K |
Ar1, K |
Mn, K |
|---|
| 700 |
810 |
400 |
350 |
336 |
Analogues
Standards
Description of chemical elements
| Element |
Units of measurement |
Description |
| Fe |
% |
Iron |
| Si |
% |
Silicon |
| Mn |
% |
Manganese |
| Cr |
% |
Chrome |
| Ti |
% |
Titan |
| Cu |
% |
Copper |
| Ni |
% |
Nickel |
| P |
% |
Phosphorus |
| C |
% |
Carbon |
| S |
% |
Sulfur |
| Mo |
% |
Molybdenum |
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 |
|
| Ar3(Arcm) |
K |
|
| Ar1 |
K |
|
| Mn |
K |
|