U7 (U7A)
Steel is not used for welded structures, not inclined. to temper embrittlement. Flock sensitivity: not sensitive. The temperature of the critical points of the alloy: Ac1 = 730, Ac3 (Acm) = 770, Ar1 = 700, Mn = 280. Substitute У8 .
a tool that works in conditions that do not cause heating of the working edge: chisels, chisels, barbs, hammers, blades of scissors for cutting metal, Axes, chisels, combination pliers, a sledgehammer.
Classification
| Country |
Section |
Category |
| CIS, Russia, Ukraine |
Tool steel |
Carbon Tool Steel |
Chemical composition
| Standard |
Fe, % |
Si, % |
Mn, % |
Cr, % |
Cu, % |
Ni, % |
P, % |
C, % |
S, % |
|---|
| GOST 1435-99 |
97.842–99.01 |
0.17–0.33 |
0.17–0.33 |
< 0.2 |
< 0.25 |
< 0.25 |
< 0.03 |
0.65–0.74 |
< 0.028 |
Information on suppliers
Physical characteristics
| Temperature, °C |
$$\varkappa$$, $$\frac{W}{m\cdot K}$$ |
$$\rho$$, $$\frac{kg}{m^3}$$ |
$$c\cdot 10^{-3}$$, $$\frac{J}{kg\cdot K}$$ |
$$R\cdot 10^{-6}$$, $$\Omega\cdot m$$ |
|---|
| 20 |
46 |
7830 |
|
0.13 |
| 100 |
46 |
|
|
|
| 300 |
41 |
|
0.58 |
|
| 400 |
|
|
0.664 |
|
| 500 |
|
|
0.819 |
|
| 600 |
33 |
|
0.97 |
|
| 700 |
|
|
0.71 |
|
| 800 |
|
|
0.706 |
|
| 900 |
29 |
|
0.685 |
|
Mechanical properties at 20 °C
| Rolling |
Standard |
Size, mm |
Tension |
Classifiers |
$$\sigma _{U}$$, $$MPa$$ |
$$\epsilon_L$$, % |
Treatment |
|---|
| Tape |
|
< 1 |
|
cold rolling |
650 |
15 |
delivery condition |
Brinell hardness number
| Rolling |
Standard |
Classifiers |
Value, HBW |
| Alloy |
GOST 1435-99 |
annealing |
1870 |
Technological Properties
| Weldability |
Flake Susceptibility |
Propensity to temper brittleness |
|---|
| Not applicable for welded structures |
not sensitive |
not inclined |
Critical point temperatures
| Ac1, K |
Ac3(Acm), K |
Ar1, K |
Mn, K |
|---|
| 730 |
770 |
700 |
280 |
Analogues
| Germany |
European Union |
Japan |
France |
Italy |
China |
Bulgaria |
Hungary |
Poland |
Romania |
Czech Republic |
Austria |
|---|
| 1.1620 (C70W2) |
CT70 |
SK7 |
C70E2U |
C70KU |
T7 |
U7 |
S71 |
N7 |
OSC7 |
19132 |
K970 |
Standards
Description of chemical elements
| Element |
Units of measurement |
Description |
| Fe |
% |
Iron |
| Si |
% |
Silicon |
| Mn |
% |
Manganese |
| Cr |
% |
Chrome |
| Cu |
% |
Copper |
| Ni |
% |
Nickel |
| P |
% |
Phosphorus |
| C |
% |
Carbon |
| S |
% |
Sulfur |
Description of physical characteristics
| Parameter |
Units of measurement |
Description |
| $$\varkappa$$ |
$$\frac{W}{m\cdot K}$$ |
Coefficient of thermal conductivity (the heat capacity of the material) |
| $$\rho$$ |
$$\frac{kg}{m^3}$$ |
The density of the material |
| $$c\cdot 10^{-3}$$ |
$$\frac{J}{kg\cdot K}$$ |
The specific heat of the material (range 20°C–T) |
| $$R\cdot 10^{-6}$$ |
$$\Omega\cdot m$$ |
Electrical resistivity |
Description of mechanical properties
| Parameter |
Units of measurement |
Description |
| $$\sigma _{U}$$ |
$$MPa$$ |
Ultimate tensile strength |
| $$\epsilon_L$$ |
% |
Elongation at break (longitudinal) |
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 |
|
| Ar1 |
K |
|
| Mn |
K |
|