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

Standard Description
GOST 1435-99

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