Steel 31Х19Н9МВБТ

Steel 31Cr19NiMVBT: a classifier of steels and alloys. Below is systematized information about the purpose, chemical composition, types of supply, substitutes, critical point temperature, physical, mechanical, technological and foundry properties for the grade — Steel 31Cr19NiMVBT.

General information about steel 31Х19Н9МВБТ

Delivery type

Bar stock, including shaped: GOST 5949−75, GOST 2590−71, GOST 2591−71, GOST 2879−69. Calibrated rod GOST 7417−75, GOST 8559−75, GOST 8560−78. Grinded rod and silversilver GOST 14955−77. Strip GOST 4405−75, GOST 103−76. Forged and forged blanks GOST 1133−71.

Application

Rotors, disks, bolts, fasteners, shafts operating at 600 ° C. The steel is heat-resistant of the outtense class.

Chemical composition of steel 31Х19Н9МВБТ

Chemical element	%
Tungsten (W)	1.0−1.5
Silicon (Si), not more than	0.8
Manganese (Mn)	0.8−1.5
Copper (Cu), not more than	0.30
Molybdenum (Mo)	1.0−1.5
Nickel (Ni)	8.0−10.0
Niobium (Nb)	0.2−0.5
Sulfur (S), max.	0.020
Titanium (Ti)	0.2−0.5
Carbon (C)	0.28−0.35
Phosphorus (P), not more than	0.035
Chrome (Cr)	18.0−20.0

Mechanical properties of steel 31Х19Н9МВБТ

Mechanical properties at elevated temperatures

t test,°C	σ0_{, 2}, MPa	_σB, MPa	_δ5, %	ψ, %	KCU, ^J/m2
rod. Disk. Hardening at 1150−1180°C with water. Aging at 700 °C, dwell time 50 h.
20	315−420	725−860	32−50	25−58	39−127
300	315	690	32	46	147
400	305	660	28	43	137
500	275	620	26	45	142
600	255	580	26	46	93
700	245	410	21	40	98
800	195	235	29	64
Disc. Rotor. Hardening 1150−1180°C, water. Aging at 750 °C, 12−15 h. (Tangential samples)
20	340−570	600−840	9−34	10−42	20−83
300	285−390	560−580	12−23	19−34	29
450	365−380	520−580	12−23	16−34	34
500	355−400	520−580	12−24	16−38	29−98
550	235−330	490−520	13−24	16−34	39
600	235−330	490−510	15−21	16−39	39−108
650	245−320	410−470	12−23	16−41	39−167
700	235−255	340−420	17−29	25−53	39−127
Bar. Disc. Hardening 1150−1180°C, water. Aging at 800 °C, 15 h, air.
20	320−390	730−820	31−44	40−49	93
600	245	480	20	46	108
650	235	430	24	55	108
Sample diameter 6 mm, length 30 mm, forged and annealed. Strain rate of 16 mm/minute. Strain rate 0.009 1/s.
800	275	315	33	68
900	205	215	28	67
1000	115	125	45	85
1100	66	80	54	90
1200	41	49	59	94

Mechanical properties of bars

Heat treatment, delivery condition	Section, mm	σ0_{, 2}, MPa	_σB, MPa	_δ5, %	ψ, %
Tempering at 1140−1180°C with water. Aging 750−800°C, 15 h, air.	60	295	590	30	40

Mechanical properties at 20 °C, depending on heat treatment

Heat treatment, delivery condition	σ0_.2, MPa	_σB, MPa	_δ5, %	ψ, %	KCU, ^J/m2
Disk diameter 900 mm. Radial specimens
Heat soak 600 °C, 6000 h	790	370	32	44	60
Heat soak 600 °C, 20,000 h	830	410	27	35	40
Heat soak 600 °C, 60000 h	860	410	19	19	24
Heat soak 650 °C, 6000 h	610	330	28	33	38
Heat soak 650 °C, 30000 h	860	430	17	17	14
Heat soak 700 °C, 1000 h	790	370	20	36	46
Heat soak 700 °C, 6000 h	810	330	16		12
Heat soak 750 °C, 6000 h	660	310			12
Heat soak 750 °C, 20,000 h	470	320			6
Heat soak 7500 °C, 40000 h	530	350			5
Heat soak 750 °C, 60000 h	430	370	3	14	6
Heat soak 800 °C, 1000 h	780	350	23	26	22
Heat soak 800 °C, 6000 h	610	340			12
Bar. Tempering 1150 °C, water.
Heat soak 650 °C, 10000 h	950	450	22	48	80

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
>108	1/100000	600	>235	10000	600
>78	1/100000	650	>216	100000	600
147−186	1/10000	600	>167	10000	650
42	1/100000	700	>147	10000	650

Technological properties of steel 31Х19Н9МВБТ

Forging temperature

Beginning 1230, the end 900. Cooling in the air.

Weldability

Difficult-to-weld. Welding method — RDS. Heat treatment is recommended for removal of welding stresses.

Machinability

In the heat-treated condition at HB 175 and _σB = 590 MPa Kυ _dv.spl. = 0.6, Kυ _b.st. = 0.3.

Heat resistance of steel 31Х19Н9МВБТ

Medium	Temperature, °С	Test duration, h	Depth, mm/year	Resistance group or grade
75%N2+17,5%O2+4%CO2+0,5%SO2	650	10000	0,01−0,011	4

Physical properties of steel 31Х19Н9МВБТ

Test temperature,°C	20	100	200	300	400	500	600	700	800	900
Modulus of normal elasticity, E, GPa	201			186	181	175	167	157
Torsional shear modulus of elasticity G, GPa	78			68	65	62	58	54
Steel density, pn, ^kg/m3	7960
Thermal conductivity coefficient W/(m — °C)		15	16	18	20	22	24	25
Electrical resistivity (p, nominal value — m)		850	900	980	1020	1080	1100	1150
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)	16.6	16.9	17.2	17.5	17.8	18.2	18.5	18.9	19.3	19.7

Steel 31Х19Н9МВБТ