Steel 37Х12Н8Г8МФБ

Steel 37Cr12N8H8G8MFB: a classifier of steels and alloys. Below is systematized information about the purpose, chemical composition, types of supply, substitutes, critical point temperatures, physical, mechanical, technological and foundry properties for the brand — Steel 37Kh12N8G8MFB.

General information on 37X12H8G8MFB steel

Delivery type

Grinded rod and silver GOST 18907−73.

Application

Fastening discs and other parts operating with a limited service life at 600−650 ° C. Steel of heat-resistant outtense class.

Chemical composition of steel 37Х12Н8Г8МФБ

Chemical element	%
Vanadium (V)	1.25−1.55
Silicon (Si)	0.3−0.8
Manganese (Mn)	7.5−9.5
Copper (Cu), not more than	0.30
Molybdenum (Mo)	1.1−1.4
Nickel (Ni)	7.0−9.0
Niobium (Nb)	0.25−0.45
Sulfur (S), max.	0.030
Carbon (C)	0.34−0.40
Phosphorus (P), not more than	0.035
Chrome (Cr)	11.5−13.5

Mechanical properties of steel 37X12H8G8MFB

Mechanical properties at elevated temperatures

t test,°C	σ0_{, 2}, MPa	_σB, MPa	_δ5, %	ψ, %	KCU, ^J/m2
Ruts with the cross-section of 20−90 mm. Hardening at 1140 °C, soaking for 1.5−2.5 hours, cooling in water. Aging at 670 °C, soaking for 12−16 hours. Aging at 780 °C, soaking for 12−16 hours. At 20 °C NV 275−302.
20	590−780	920−1060	16−24	24−43	31−51
200	540	750	15	37
300	520	730	12	36
400	490	710	15	36
500	480−570	670−750	13−17	32−42	69
600	450−560	590−690	10−16	36−44	49−78
650	420−530	550−630	11−19	34−45	49−78
700	370−520	490−580	10−18	23−39	69
Discs. Hardening 1140−1150°C, water. Aging at 670 °C, holding for 16 h. Aging at 720 °C, holding for 12 hours. At 20 °C NV 354.
20	910	1100	10	32
200	820	960	9	36
300	810	930	8	31
400	780	900	9	24
500	710	830	9	30
600	650	710	6	28
650	630	710	5	18
Specimen 10 mm in diameter and 50 mm in length, rolled and annealed. Deformation rate of 20 mm/minute. Strain rate 0.007 1/s.
800	245	350	12	22
900	165	180	22	59
1000	83	92	38	78
1100	47	49	45	88
1200	24	26	51	79
1250	20	21	21	41

Mechanical properties as a function of heat soak and test temperature

Heat treatment, delivery condition	t test temperature,°C	σ0_{, 2}, MPa	_σB, MPa	_δ5, %	ψ, %	KCU, ^J/m2
Rods with 90 mm cross-section. Hardening at 1145 °C, soaking for 2.5 hours with water. Aging at 670 °C, holding for 16 h. Aging at 780 °C, hold for 16 h.
Heat soaking at 550 °C, 5,000 °C	20	650−760	1010	19−22	30	37−41
Heat soak 550 °C, 5000 °C	650	490−540	560	10−19	31−47
Heat soak 600 °C, 5000 °C	20	660−700	980	19−22	28	34
Heat soak 600 °C, 5000 °C	650	495	570	15−18	38−45
Heat soaking 650 °C, 5000 °C	20	500	880	25	30	34
Heat soak 650 °C, 5000 °C	650	390	510	13	42
Heat soak 700 °C, 5000 °C	20	450	810	24−29	30	29
Heat soak 700 °C, 5000 °C	650	280	440−470	16−20	43

Mechanical properties in the long term strength test

Creep strength, MPa	Creep rate, %/h	t test,°C	Ultimate long-term strength, MPa	Test duration, h	t test, h
372−441	10000	550	333−421	1000	600
333	10000	600	225	1000	700
235	10000	650	294−353	10000	600
162	10000	700	176	10000	700

Technological properties of 37X12H8G8MFB steel

Forging temperature

The beginning 1220, the end 900. Sections up to 350 mm are cooled in the air.

Weldability

Limited weldability. Welding methods: РДС (electrodes ЦТ-10), ЕШС. Subsequent heat treatment is recommended.

machinability by cutting

In the heat-treated condition with NV 269 Kυ _dv.spl. = 0.4, Kυ _b.st. = 0.2.

Endurance limit of steel 37Х12Н8Г8МФБ

_σ-1, MPa

421

Physical properties of steel 37Cr12Ni8MoVrB

Test temperature, °С	20	100	200	300	400	500	600	700	800	900
Modulus of normal elasticity, E, GPa	171		157	147	140	133	125	115
Steel density, pn, ^kg/m3	7850
Thermal conductivity coefficient W/(m — °C)		17	18	20	21	23	25	26	27	29
Electrical resistivity (p, nominal value — m)	740	850	900	950	1010	1100	1150	1200
Test temperature,°C	20−100	20−200	20−300	20−400	20−500	20−600	20−700	20−800	20−900	20−1000
Coefficient of linear expansion (a, 10−6 1/°C)	15.8

Steel 37Х12Н8Г8МФБ