03Н18К8М5Т steel (VKS-170; ЭК21)

Designation

Name	The value
Designation GOST Cyrillic	03Н18К8М5Т
Designation GOST Latin	03H18K8M5T
Transliteration	03N18K8M5T
By chemical elements	03Н18Co8Mo5Ti

Name	The value
Designation GOST Cyrillic	ВКС-170
Designation GOST Latin	BKC-170
Transliteration	VKS-170
By chemical elements	WCoС-170

Name	The value
Designation GOST Cyrillic	ЭК21
Designation GOST Latin	EK21
Transliteration	EhK21
By chemical elements	-

Description

03Н18К8М5Т steel is used: for the production of bodies of rocket motors, the shafts of helicopters, welded hulls, engines, pressure vessels of large dimensions, body parts for submarines, submersibles, high-load disc turbines, gears and parts gears, spindles.

Note

Maraging steel with higher structural stability in the temperature range from cryogenic to +450 °C.

Standards

Name	Code	Standards
Classification, nomenclature and General rules	В20	OST 1 90005-91
Bars and shapes	В32	TU 14-1-4479-88, TU 14-1-3404-82, TU 14-1-3140-81

Chemical composition

Standard	C	S	P	Mn	Cr	Si	Ni	Fe	Al	Ti	Mo	Co
TU 14-1-3140-81	≤0.03	≤0.01	≤0.01	≤0.1	≤0.3	≤0.1	17.7-19	Rest	≤0.15	0.2-0.4	4.2-5	7.5-8.5

Fe is the basis.
According to TU 14-1-3404-82, the chemical composition is given for steel grade 03Н18К8М5Т-ВД (ЭК21-ВД, ВКС170ВД). Estimated content of modifiers and deoxidizers: magnesium, cerium, hafnium, germanium and boron is established by the supplier's technological instructions and their residual content in the metal is not determined by chemical analysis. A residual chromium content of up to 0.30% is allowed. In the finished product, deviations in chemical composition are permissible: for silicon and manganese, provided that their sum is not more than 0.20% for sulfur and phosphorus, provided that their sum is not more than 0.020%, for nickel by minus 0.20% .
According to TU 14-1-3140-81, the chemical composition is given for steel grade 03N18K8M5T-VD (EC21-VD, VKS170-VD). Estimated content of modifiers and deoxidizers: magnesium, cerium, hafnium, germanium and boron is established by the supplier's technological instructions and their residual content in the metal is not determined by chemical analysis. In the finished product, deviations in chemical composition are allowed: for silicon and manganese, provided that their sum is not more than 0.20%, sulfur and phosphorus, provided that their sum is not more than 0.020%, in nickel by minus 0.20 %.
According to TU 14-1-4479-88, the chemical composition is given for steel grades 03N18K8M5T-VD (EC21-VD) and 03N18K8M5T-ID (EC21-ID). In the finished product deviations in chemical composition are allowed: for silicon and manganese, provided that their amount will not be more than 0.20%; on sulfur and phosphorus, provided that their sum will not exceed 0.020%; for nickel minus 0.20%. A residual chromium content of up to 0.30% is allowed. The calculated content of modifiers and deoxidizers: magnesium, cerium, boron, etc. is established by the supplier's technological instructions and their residual content in the metal is not determined by chemical analysis.

Mechanical properties

Section, mm	s_T\|s_0,2, MPa	σ_U, MPa	y, %	KCU, kJ/m²	HRC
Gradation of performance properties of the finished heat-treated parts for OST 1 90005-91
-	-	1570-1810	-	-	45.5-48.5
Bars hot rolled as supplied on the other 14-1-3404-82 (in the state of delivery indicate the direction of cutting out of samples)
-	-	≥1570	≥35	≥340	-
-	-	≥1570	≥50	≥490	-
Bars hot rolled on the other 14-1-3140-81. In the state of delivery indicated in the cutting direction of the samples. Quenching in water from 1150-1200 °C (aging for 1 h) + Quenching in water from 930-950 °C (aging for 1 h) + Quenching in air 780-800 °C (delay of 1-3 h) + Aging at 500-550 °C (exposure for 2-8 hours), air cooling
Образец 15х15	≥1470	≥1570	≥35	≥340	-
Образец 15х15	≥1470	≥1570	≥50	≥490	-
Bars and rods, hot rolled, forged and strip forged on the other 14-1-4479-88. In the state of delivery specified steel grade and the cutting direction of the samples. Quenching in water from 1150-1200 °C (aging 1 HR) + Triple quenching quenching in water from 930-950 °C (aging for 1 h) + Quenching in air 780-800 °C (delay of 1-3 h) + Aging at 500-550 °C (exposure for 2-8 hours), air cooling
15	-	≥1570	≥35	≥340	-
15	-	≥1570	≥50	≥490	-
15	-	≥1570	≥40	≥392	-
15	-	≥1570	≥50	≥490	-
The rolled bars on the other 14-1-3404-82. The longitudinal samples. Annealing in air 780-800 °C (aging 1 HR) + Aging at 490-510 °C (exposure for 2-8 hours), air cooling
	≥1471	≥1570	≥50	≥490	-

Description mechanical marks

Name	Description
s_T\|s_0,2	Yield strength or limit of proportionality with a tolerance for residual deformation of 0.2%
σ_U	Limit short-term strength
y	The relative narrowing
KCU	Toughness
HRC	Rockwell hardness (indenter diamond spheroconical)

Physical characteristics

Temperature	Е, HPa	r, kg/m³	a, 10^-6 1/°C
20	197	8120	80-11

A description of the physical symbols

Name	Description
Е	The normal elasticity modulus
r	Density
l	Coefficient of thermal conductivity

Technological properties

Name	The value
Macrostructure and pollution	The macrostructure of the steel valley not to have shrinkage in looseness, bubbles, cracks, inclusions, brown, bundles, visible without using the magnifying devices.