Steel 37KH12N8G8MFB (ЭИ481)

Designation

Name	The value
Designation GOST Cyrillic	37Х12Н8Г8МФБ
Designation GOST Latin	37X12H8G8MFB
Transliteration	37H12N8G8MFB
By chemical elements	37Cr12Н8Mn8MoVNb

Name	The value
Designation GOST Cyrillic	ЭИ481
Designation GOST Latin	EI481
Transliteration	EhI481
By chemical elements	-

Description

37KH12N8G8MFB steel is used: for the manufacture of turbine disks, fasteners and other components; parts operating under high voltage.

Note

Steel complexly alloyed heat-resistant austenitic class.
The recommended maximum operating temperature for a long time +630 °C.
The temperature of beginning of intensive scaling in air +750 °C.

Standards

Name	Code	Standards
Bars and shapes	В32	GOST 18907-73, TU 14-1-1923-76, TU 14-1-3957-85, TU 14-11-245-88
Classification, nomenclature and General rules	В30	GOST 5632-72
Blanks. Of the workpiece. Slabs	В21	OST 1 90176-75
Blanks. Of the workpiece. Slabs	В31	OST 3-1686-90, OST 1 90162-74, TU 14-1-1213-75, TU 14-1-226-72
Thermal and thermochemical treatment of metals	В04	STP 26.260.484-2004

Chemical composition

Standard	C	S	P	Mn	Cr	Si	Ni	Fe	Cu	V	Ti	Mo	Nb
TU 14-1-1213-75	0.35-0.4	≤0.015	≤0.035	7.5-9.5	11.5-13.5	0.3-0.7	7-9	Rest	≤0.2	1.25-1.55	≤0.12	1.1-1.4	0.35-0.45
TU 14-1-1923-76	0.35-0.4	≤0.03	≤0.035	7.5-9.5	11.5-13.5	0.3-0.7	7-9	Rest	≤0.2	1.25-1.55	≤0.12	1.1-1.4	0.35-0.45
GOST 5632-72	0.34-0.4	≤0.03	≤0.035	7.5-9.5	11.5-13.5	0.3-0.8	7-9	Rest	≤0.3	1.3-1.5	≤0.2	1.1-1.4	0.25-0.45

Fe is the basis.
According to TU 14-1-1923-76 the chemical composition is given for steel grades 37Х12Н8Г8МФБ (ЭИ481). In steel 37Х12Н8Г8МФБ-Ш (ЭИ481-Ш) electroslag remelting the sulfur content should not be more than 0,015% with an allowable deviation of + 0,0050%. Deviations in chemical composition are allowed in both grades: niobium + 0.15%, vanadium + 0.10%, carbon + 0.020%, molybdenum -0.020%. The content of copper and titanium is indicated as residual.
According to TU 14-1-1213-75 the chemical composition is given for steel grades 37Х12Н8Г8МФБ-Ш (ЭИ481-Ш). In the finished product, deviations in niobium + 0.15%, vanadium + 0.10%, carbon + 0.020% are allowed. At the consumer's request, a deflection on carbon may not be tolerated. For other elements, deviations are allowed in accordance with GOST 5632. The mass fraction of residual copper should not exceed 0.20%, titanium - 0.12%. The mass determines the mass fraction of nitrogen, the results are recorded in the certificate.

Mechanical properties

Section, mm	s_T\|s_0,2, MPa	σ_U, MPa	d₅, %	y, %	KCU, kJ/m²	HB, MPa
Rods made of steel 37KH12N8G8MFB (ЭИ481) TU 14-1-1923-76. Quenching with 1140-1160 °C, exposure for 1 h 20 min. (for workpieces up to ø 45 mm) and 1 hour 45 minutes (for workpieces ø 45-90 mm), full cooling in water
	≥590	≥880	≥15	≥20	≥294	277-311
Disks. Quenching in water from 1140-1150 °C + Aging at 670 °C (16 h exposure) + Aging at 720 °C (exposure 12 h) At 20 °C NV=354
-	≥910	≥1100	≥10	≥32	-	-
Bars with cross-section 90 mm. Quenching in water from 1145 °C (exposure 2.5 h) + Aging at 670 °C (16 h exposure) + Aging at 780 °C (the aging 16 hours) (provided the temperature and duration of heat exposure)
-	650-760	1010	19-22	30	-	-
Rods made of steel 37KH12N8G8MFB-sh (ЭИ481-W) on the other 14-1-1923-76. Aging at 670 °C, exposure time of 12-14 h, temperature rise up to 770-800 °C, exposure time 10-12 hours, air cooling
	≥590	≥880	≥18	≥22	≥294	277-311
Disks. Quenching in water from 1140-1150 °C + Aging at 670 °C (16 h exposure) + Aging at 720 °C (exposure 12 h) At 20 °C NV=354
-	≥820	≥960	≥9	≥36	-	-
Bars with cross-section 90 mm. Quenching in water from 1145 °C (exposure 2.5 h) + Aging at 670 °C (16 h exposure) + Aging at 780 °C (the aging 16 hours) (provided the temperature and duration of heat exposure)
-	490-540	560	10-19	31-47	-	-
Bars hot rolled and forged at STP 26.260.484-2004. Quenching in water from 1130-1150 °C to + First aging at 660-680 °C, exposure for 12 to 14 h, air cooling + ageing at the Second 770-800 °C, exposure time 10-12 h, air cooling
	≥600	≥900	≥15	≥20	-	-
Disks. Quenching in water from 1140-1150 °C + Aging at 670 °C (16 h exposure) + Aging at 720 °C (exposure 12 h) At 20 °C NV=354
-	≥810	≥930	≥8	≥31	-	-
Bars with cross-section 90 mm. Quenching in water from 1145 °C (exposure 2.5 h) + Aging at 670 °C (16 h exposure) + Aging at 780 °C (the aging 16 hours) (provided the temperature and duration of heat exposure)
-	660-700	980	19-22	28	-	-
Rolled steel. Heating 1140-1160 °C (aging for 1 h), cooling in water + Aging at 660-790 °C (aging 10-16 h), air cooling
≤60	≥600	≥1000	≥20	≥25	≥343	-
Disks. Quenching in water from 1140-1150 °C + Aging at 670 °C (16 h exposure) + Aging at 720 °C (exposure 12 h) At 20 °C NV=354
-	≥780	≥900	≥9	≥24	-	-
Bars with cross-section 90 mm. Quenching in water from 1145 °C (exposure 2.5 h) + Aging at 670 °C (16 h exposure) + Aging at 780 °C (the aging 16 hours) (provided the temperature and duration of heat exposure)
-	495	570	15-18	38-45	-	-
Forming at OST 1 90176-75. Quenching in water from 1140-1160 °C (extract 1,75-2,50 h), complete cooling in water + Aging at 670 °C (16 h exposure) + Heating to 770-790 °C (aging from 16 to 20 h), air cooling
	≥589	≥883	≥15	≥20	≥245	277-311
Disks. Quenching in water from 1140-1150 °C + Aging at 670 °C (16 h exposure) + Aging at 720 °C (exposure 12 h) At 20 °C NV=354
-	≥710	≥830	≥9	≥30	-	-
Bars with cross-section 90 mm. Quenching in water from 1145 °C (exposure 2.5 h) + Aging at 670 °C (16 h exposure) + Aging at 780 °C (the aging 16 hours) (provided the temperature and duration of heat exposure)
-	500	880	25	30	-	-
Forming at OST 1 90176-75. Quenching in water from 1140-1160 °C (extract 1,75-2,50 h), complete cooling in water + Aging at 670 °C (16 h exposure) + Heating to 770-790 °C (aging from 16 to 20 h), air cooling
	≥589	≥912	≥18	≥22	≥294	277-311
Disks. Quenching in water from 1140-1150 °C + Aging at 670 °C (16 h exposure) + Aging at 720 °C (exposure 12 h) At 20 °C NV=354
-	≥650	≥710	≥6	≥28	-	-
Bars with cross-section 90 mm. Quenching in water from 1145 °C (exposure 2.5 h) + Aging at 670 °C (16 h exposure) + Aging at 780 °C (the aging 16 hours) (provided the temperature and duration of heat exposure)
-	390	510	13	42	-	-
Disks. Quenching in water from 1140-1150 °C + Aging at 670 °C (16 h exposure) + Aging at 720 °C (exposure 12 h) At 20 °C NV=354
-	≥630	≥710	≥5	≥18	-	-
Bars with cross-section 90 mm. Quenching in water from 1145 °C (exposure 2.5 h) + Aging at 670 °C (16 h exposure) + Aging at 780 °C (the aging 16 hours) (provided the temperature and duration of heat exposure)
-	450	810	24-29	30	-	-
A sample with a diameter of 10 mm and a length of 50 mm, laminated and annealed. The rate of deformation of 20 mm/min strain Rate 0,007 1/C
-	≥245	≥350	≥12	≥22	-	-
Bars with cross-section 90 mm. Quenching in water from 1145 °C (exposure 2.5 h) + Aging at 670 °C (16 h exposure) + Aging at 780 °C (the aging 16 hours) (provided the temperature and duration of heat exposure)
-	280	440-470	16-20	43	-	-
A sample with a diameter of 10 mm and a length of 50 mm, laminated and annealed. The rate of deformation of 20 mm/min strain Rate 0,007 1/C
-	≥165	≥180	≥22	≥59	-	-
-	≥83	≥92	≥38	≥78	-	-
-	≥47	≥49	≥45	≥88	-	-
-	≥24	≥26	≥51	≥79	-	-
-	≥20	≥21	≥21	≥41	-	-
Bars section 20-90 mm. Quenching in water from 1140 °C (exposure for 1.5-2.5 h) + Aging at 670 °C (delay of 12-16 h) + Aging 780 °C (delay of 12-16 h). At 20 °C NV=275-302
-	590-780	920-1060	16-24	24-43	-	-
-	540	750	15	37	-	-
-	520	730	12	36	-	-
-	490	710	15	36	-	-
-	480-570	670-750	13-17	32-42	-	-
-	450-560	590-690	10-16	36-44	-	-
-	420-530	550-630	11-19	34-45	-	-
-	370-520	490-580	10-18	23-39	-	-

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
d₅	Elongation after rupture
y	The relative narrowing
KCU	Toughness
HB	Brinell hardness number

Physical characteristics

Temperature	Е, HPa	r, kg/m³	l, W/(m · °C)	R, Mr. · m	a, 10^-6 1/°C
0	171	7850	-	740	-
20	174	7850	-	740	-
200	157	-	18	900	171
300	147	-	20	950	158
400	140	-	21	1010	192
500	133	-	23	1100	203
600	125	-	25	1150	212
700	115	-	26	1200	222
100	-	-	17	850	159
800	-	-	27	-	232
900	-	-	29	-	242

A description of the physical symbols

Name	Description
Е	The normal elasticity modulus
r	Density
l	Coefficient of thermal conductivity
R	UD. the resistivity

Technological properties

Name	The value
Weldability	limited weldability. Welding methods: SMAW (electrodes DH-10), ESW. Recommended subsequent heat treatment.
The temperature of forging	Beginning - 1220 °C, the end of - 900 °C. the cross Sections up to 350 mm cooled in air.
Machinability	In the heat treated condition while HB 269 Kn TV.SPL.=0.4 Kn b.St.=0.2
Features of heat treatment	Steel products 37KH12N8G8MFB for equipment chemical industry should termoobrabotki regime - hardening with 1130-1150 °C water + aging at first 660-680 °C with an exposure 12-14 hours, and air cooling + ageing at the second 770-800 °C with a delay of 10-12 hours and air cooling.