Steel 20K

Designation

Name	The value
Designation GOST Cyrillic	20К
Designation GOST Latin	20K
Transliteration	20K
By chemical elements	20

Description

20K steel is used: for the manufacture of flanges, bottoms, telecomandi and welded the drums of steam boilers; coupling parts, chassis bodies and other parts of the boiler and vessels, working under pressure and at temperatures up to +450 °C; as a base layer in the manufacture of hot-rolled dual-layer corrosion-resistant sheets.

Standards

Name	Code	Standards
Sheets and strips	В33	GOST 10885-85, TU 14-1-3922-84, TU 14-1-4088-86
Sheets and strips	В23	GOST 5520-79, GOST 19903-74, GOST 19903-90
Classification, nomenclature and General rules	В30	TT 232-41-2007
Blanks. Of the workpiece. Slabs	В31	TU 05764417-013-93

Chemical composition

Standard	C	S	P	Mn	Cr	Si	Ni	Fe	Cu	N	As	Al	V	Ca
TU 14-1-3922-84	0.16-0.24	≤0.04	≤0.04	0.35-0.65	≤0.3	0.15-0.3	≤0.3	Rest	≤0.3	≤0.008	≤0.08	-	-	-
TU 05764417-013-93	0.18-0.22	≤0.008	≤0.012	0.5-0.8	≤0.4	0.2-0.4	≤0.4	Rest	≤0.3	-	-	0.01-0.04	0.05	0.02
TT 232-41-2007	0.18-0.22	≤0.008	≤0.015	0.5-0.8	≤0.4	0.2-0.4	≤0.4	Rest	≤0.3	-	-	0.01-0.04	0.05	0.02

Fe is the basis.
According to GOST 5520-79 in the sheets up to 20 mm thick, the mass fraction of manganese is allowed up to 0.80%. When smelting steel from the Kerch ores, the mass fraction of arsenic is allowed up to 0.15%, while the mass fraction of phosphorus should not be more than 0.030%. At the request of the consumer, the mass fraction of sulfur should not exceed 0.025, 0.030 or 0.035%, and phosphorus 0.030 or 0.035%. When steel is smelted in electric furnaces, the mass fraction of nitrogen must be ≤ 0.012%.
According to TU 05764417-013-93 the chemical composition is given for steel grade 20KA. The content of vanadium and calcium in steel is not calculated and chemically analyzed.
According to ТТ 232-41-2007 the chemical composition is given for steel grade 20KA. The content of elements (vanadium and calcium), calculated by chemical analysis, is not determined.

Mechanical properties

Section, mm	s_T\|s_0,2, MPa	σ_U, MPa	d₅, %	y, %	KCU, kJ/m²	HB, MPa
Steel hot-rolled sheet in the delivery condition
21-40	≥240	≥410	≥24	-	≥637	-
4-20	≥250	≥410	≥24	-	≥686	-
41-60	≥230	≥410	≥24	-	≥588	-
Casting as supplied. Without heat treatment
-	≥220	≥420	≥22	≥35	≥490	-
Sheet gracieacademy (specified time and temperature of exposure)
-	235-245	425	30-32	59-83	-	-
-	185-215	350-360	27-31	65-68	-	-
-	235	395	32	62	-	-
-	175-195	360	30-33	62-64	-	-
-	210	395	29-31	60-62	-	-
Sheets hot rolled 37-40 mm
-	215-245	400-440	30	56	-	-
-	195	390	20	47-55	-	-
-	195	-	15-17	39	-	-
-	165	-	23	44-51	-	-
-	165	370	24	61	-	-
-	155	250	23	61	-	-
-	59	110	31-37	73-81	-	-
Sheets hot rolled 37-40 mm. Annealing at 880-900 °C
-	245	400-430	30	55-60	-	-
-	180-225	350-500	17-28	43-62	-	-
-	145-185	350-510	24	52-60	-	-
-	135-175	320-400	22-33	60-73	-	-
-	120-150	200-270	24-43	71-83	-	-
-	69-98	110-150	36-48	84-91	-	-
Procurement for vessels working under pressure on the other 05764417-013-93 supplied after the main heat treatment (samples for forgings, longitudinal, - transverse; KCU - after mechanical aging)
	≥275	430-590	≥23	≥55	≥290	≥140
Sheet metal, steel, 20KA at TT 232-41-2007 after heat treatment. In the graph indicated the value of KCU KCV
	≥275	430-590	≥23	-	≥490	-
Leaves categories: 2-5, 10, 11, 16, 18-21 (KCU - as supplied / after mechanical aging)
≤5	≥245	≤510	≥25	-	-	-
21-40	≥235	400-510	≥24	-	≥540/245	-
41-60	≥225	400-510	≥23	-	≥490/245	-
5-20	≥245	400-510	≥25	-	≥588/294	-
The plates on the other 14-1-3922-84. Normalized samples
	≥206	≥392	≥20	-	≥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
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	207	7850	-	-	-	-
20	211	7870	-	200	-	482
100	204	7840	51	219	-	486
200	201	7810	49	292	119	470
300	196	7780	46	381	128	483
400	187	7740	42	487	132	533
500	176	7710	39	601	136	538
600	162	7670	36	758	136	584
700	-	7630	-	925	-	571
800	-	7640	-	1094	139	703
900	-	7610	-	1135	-	703
1000	-	7550	-	1167	-	695
1100	-	7490	-	1194	-	691
1200	-	-	-	1219	-	687

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. The welding methods of SMAW, ADS submerged arc and gas protection electroslag welding.
Склонность к отпускной хрупкости	Tend not.
The temperature of forging	Start - 1260 °C, the end - 750 °C.
Flock-sensitive sensitivity	not sensitive
Machinability	In the annealed condition with NV 121-126 and blower SB=390 MPa Kn TV.SPL.=1,50 Kn b.St.=Of 1.35.
Macrostructure and pollution	The macrostructure of the steel on the etched templeto should not be visible during visual inspection of cracks, delamination, placenow, bubbles. Allowed black travelmasti without discontinuity of metal with a length of not more than 15 mm, and a separate slag inclusions. The amount of nonmetallic inclusions (in points), estimated collectively defined by GOST 1778, shall not exceed the standards for average score: sulfides, oxides, stroke, silicates fragile 2.5 points for each parameter; the non-deformed silicates - 3.0 points. Sulfide and oxide nonmetallic inclusions should have a shape close to globular. Allowed separate sulfide inclusions elongated shape.
Microstructure	The size of the actual grain should be no larger than 7 numbers according to GOST 5639. The banding structure of sheet metal must not exceed a score of 3 on a scale GOST 5640.