Steel 12MKH

Designation

Name	The value
Designation GOST Cyrillic	12МХ
Designation GOST Latin	12MX
Transliteration	12MH
By chemical elements	12MoCr

Description

12MKH steel is used: for the manufacture of superheater pipes, pipelines and collector installations high pressure; forgings of parts for steam boilers and steam pipes; parts, cylinders of gas turbines; various parts operating at temperatures up to +510 °C; as a base layer in the manufacture of hot-rolled dual-layer corrosion-resistant sheets.

Note

Steel pearlitic class.
Temperature intense scaling +570 °C.

Standards

Name	Code	Standards
Bars and shapes	В22	GOST 1133-71, GOST 2590-2006, GOST 2591-2006
Sheets and strips	В23	GOST 19903-74, GOST 103-2006, GOST 19903-90
Sheets and strips	В33	GOST 4405-75, GOST 10885-85, TU 108.1263-84, TU 14-1-642-73, TU 24-10-003-70, TU 14-1-5093-92
Steel pipes and fittings to them	В62	GOST 550-75, TU 14-3-463-2005
Bars and shapes	В32	GOST 7417-75, GOST 8559-75, GOST 8560-78, GOST 14955-77, GOST 20072-74, TU 14-11-245-88
Processing of metals by pressure. Forgings	В03	OST 5Р.9125-84, TU 0306.018-80
Blanks. Of the workpiece. Slabs	В31	TU 14-1-1263-75

Chemical composition

Standard	C	S	P	Mn	Cr	Si	Ni	Fe	Cu	V	Ti	Mo	W
GOST 20072-74	0.09-0.16	≤0.025	≤0.03	0.4-0.7	0.4-0.7	0.17-0.37	≤0.3	Rest	≤0.2	≤0.05	≤0.03	0.4-0.6	≤0.2

Fe is the basis.
According to GOST 20072-74, when steel is scrap-process, the content of Cu ≤ 0.30%. Tungsten is allowed up to 0.20%, vanadium up to 0.050%, titanium up to 0.030%. When smelting steel by the method of electroslag remelting, the mass fraction of sulfur should not be more than 0.015%.
According to TU 108.1263-84, steel should be smelted in an open-hearth furnace or an electric arc furnace. It is permitted to process steel at the OSRP.

Mechanical properties

Section, mm	s_T\|s_0,2, MPa	σ_U, MPa	d₅, %	y, %	KCU, kJ/m²	HB, MPa
Steel hot-rolled sheet, heat treated in the delivery condition (transverse specimens)
5-25	≥235	≥440	≥24	-	≥579	-
Leaves section 20-160 mm
130-160	≥195	≥340	≥18	≥32	≥490	-
Pipe with a diameter of 273 mm with a wall thickness of 28 mm. Normalizing at 920 °C, air cooling + Vacation at 680-690 °C, air cooling
-	≥280	≥445	≥32	≥67	-	-
Sheet double layer in the delivery state according to GOST 10885-85 (samples transverse)
12-40	≥221	≥420	≥24	-	≥588	-
Leaves section 20-160 mm
130-160	≥215	≥390	≥18	≥32	≥490	-
Pipe with a diameter of 273 mm with a wall thickness of 28 mm. Normalizing at 920 °C, air cooling + Vacation at 680-690 °C, air cooling
-	≥250	≥450	≥20	≥62	-	-
Sheet. Quenching in water from 900-920 °C + Vacation at 670-720 °C, air cooling (samples transverse)
4-60	≥235	≥440	≥24	-	≥579	≥182
Leaves section 20-160 mm
60-130	≥215	≥390	≥18	≥32	≥490	-
Pipe with a diameter of 273 mm with a wall thickness of 28 mm. Normalizing at 920 °C, air cooling + Vacation at 680-690 °C, air cooling
-	≥290	≥480	≥20	≥57	-	-
Sheet. Quenching in water from 900-920 °C + Vacation at 670-720 °C, air cooling (samples transverse)
61-125	≥235	≥440	≥18	≥32	≥481	-
Leaves section 20-160 mm
60-130	≥235	≥440	≥18	≥32	≥490	-
Pipe with a diameter of 273 mm with a wall thickness of 28 mm. Normalizing at 920 °C, air cooling + Vacation at 680-690 °C, air cooling
-	≥250	≥450	≥23	≥62	-	-
Forgings for parts resistant to the ICC. Normalization at 910-930 °C, air cooling + Vacation at 670-690 °C, air cooling
	≥235	≥412	≥21	≥45	≥579	-
Leaves section 20-160 mm
20-39	≥235	≥440	≥19	≥35	≥490	-
Pipe with a diameter of 273 mm with a wall thickness of 28 mm. Normalizing at 920 °C, air cooling + Vacation at 680-690 °C, air cooling
-	≥235	≥400	≥22	≥62	-	-
Rolled steel. Normalization at 910-930 °C, air cooling + Vacation at 670-690 °C, air cooling
≤90	≥235	≥410	≥21	≥45	≥579	-
Leaves section 20-160 mm
40-60	≥235	≥440	≥19	≥35	≥490	-
Pipe with a diameter of 273 mm with a wall thickness of 28 mm. Normalizing at 920 °C, air cooling + Vacation at 680-690 °C, air cooling
-	≥220	≥360	≥22	≥64	-	-
The tubular billet (D = 80-270 mm) as supplied on THAT 14-1-1263-75. Normalization at 910-930 °C, air cooling
20-25	≥206	≥412	≥21	≥50	≥686	-
Leaves section 20-160 mm
20-39	≥235	≥390	≥19	≥35	≥490	-
Pipe with a diameter of 273 mm with a wall thickness of 28 mm. Normalizing at 920 °C, air cooling + Vacation at 680-690 °C, air cooling
-	≥220	≥310	≥26	≥64	-	-
The tubular billet (D = 80-270 mm) as supplied on THAT 14-1-1263-75. Vacation at 670-700 °C, air cooling
20-25	≥206	≥412	≥19	≥45	≥490	-
Leaves section 20-160 mm
40-60	≥235	≥390	≥19	≥35	≥490	-
Seamless hot deformed tubes, heat-treated in the delivery condition according to GOST 550-75
	≥245	≥410	≥21	≥45	≥690	≤156
Leaves section 20-160 mm
130-160	≥295	≥440	≥20	≥50	≥780	-
40-130	≥340	≥490	≥20	≥50	≥780	-

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	С, J/(kg · °C)
0	212	7850	-	-	-	-
100	206	7830	50	240	112	473
200	200	7800	50	330	125	519
300	195	7760	50	410	127	565
400	189	7730	49	540	129	594
500	179	7690	47	640	132	653
600	170	7650	46	740	-	733
700	160	7610	44	900	135	-
900	-	-	-	-	138	-
800	-	-	-	-	-	888
1000	-	-	-	-	-	1365

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	Welded without any restrictions. Welding methods: SMAW, ADS under gas protection, the CCC. Recommended heating and subsequent heat treatment.
Склонность к отпускной хрупкости	Tend not.
The temperature of forging	Start - 1260 °C, the end - 750 °C.
Flock-sensitive sensitivity	Sensitive.
Machinability	In the normalized and tempered condition, when blower SB 138 HB=460 MPa Kn b.St.=1.4.