50G

Friction disc, shafts, gears, spline shafts, connecting rods, electrical rollers, sleeve bearings, cranks, spindles, wheels flywheels, crankshafts of diesel and natural gas engines and other parts, which are requirements of high strength and wear resistance.

Classification

Country	Section	Category
Country	Section	Category
CIS, Russia, Ukraine	Structural steel	Alloyed structural steel

Chemical composition

Standard	Fe, %	Si, %	Mn, %	Cr, %	Cu, %	Ni, %	P, %	C, %	S, %
Standard	Fe, %	Si, %	Mn, %	Cr, %	Cu, %	Ni, %	P, %	C, %	S, %
GOST 4543-71	97.1–98.65	0.17–0.37	0.7–1	< 0.3	< 0.3	< 0.3	< 0.035	0.48–0.56	< 0.035

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Physical characteristics

Temperature, °C	$E\cdot 10^{9}$ , $MPa$	$\alpha\cdot 10^{6}$ , $K^{-1}$	$\varkappa$ , $\frac{W}{m\cdot K}$	$\rho$ , $\frac{kg}{m^3}$	$c\cdot 10^{-3}$ , $\frac{J}{kg\cdot K}$
Temperature, °C	$E\cdot 10^{9}$ , $MPa$	$\alpha\cdot 10^{6}$ , $K^{-1}$	$\varkappa$ , $\frac{W}{m\cdot K}$	$\rho$ , $\frac{kg}{m^3}$	$c\cdot 10^{-3}$ , $\frac{J}{kg\cdot K}$
20	216		43	7810
100	213	11.8	42		0.487
200	208	12.5	41		0.5
300	199	13.2	38		0.517
400	185	13.8	36		0.533
500	174	14.3	34		0.559
600	160	14.8	31		0.584
700	142	15.1	29		0.609
800	130	12.3	28		0.676

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
Rolling	Standard	Size, mm	Tension	Classifiers	$\sigma _{U}$ , $MPa$	$\sigma_{P}$ , $MPa$	$\epsilon_L$ , %	$\psi$ , %	$KCU\cdot 10^{3}$ , $\frac{J}{m^2}$	Treatment
Round	GOST 4543-71	25			650	390	13	40	390	Hardening and tempering
The tape is annealed.	GOST 2283-79				640–740		10–15
The tape is hardcore.	GOST 2283-79				740–1180

Brinell hardness number

Rolling	Standard	Classifiers	Value, HBW
Rolling	Standard	Classifiers	Value, HBW
Alloy	GOST 4543-71	annealing	229
The plates	GOST 1577-93	normalization	255
The plates	GOST 1577-93	annealing	217

Technological Properties

Weldability	Flake Susceptibility	Propensity to temper brittleness
Weldability	Flake Susceptibility	Propensity to temper brittleness
Difficult to weld	sensitive	inclined

Critical point temperatures

Ac₁, K	Ac₃(Ac_m), K	Ar₃(Arc_m), K	Ar₁, K	Mn, K
Ac₁, K	Ac₃(Ac_m), K	Ar₃(Arc_m), K	Ar₁, K	Mn, K
723	760	740	680	320

Analogues

USA
USA
1050

Standards

Standard	Description
Standard	Description
GOST 4543-71

Description of chemical elements

Element	Units of measurement	Description
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
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
$c\cdot 10^{-3}$	$\frac{J}{kg\cdot K}$	The specific heat of the material (range 20°C–T)

Description of mechanical properties

Parameter	Units of measurement	Description
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
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
Parameter	Units of measurement	Description
Ac₁	K
Ac₃(Ac_m)	K
Ar₃(Arc_m)	K
Ar₁	K
Mn	K