Determination of the alloys grade

If the steel marking has the letter C at the end, it means that the steel is case-hardened, if the letter A - the steel has a reduced amount of harmful impurities (sulfur and phosphorus).

The presence of alloyed additives greatly alters the properties of the steel itself. The content of both chromium and nickel in steel increases its toughness and hardness. The presence of nickel alone makes steel not only tough, but also gives it the ability to withstand shock loads. Alloyed additives in the form of chromium and silicon make steel tough and easier to heat treatment.

A special place is occupied by electrical low-carbon steels, which are used for the manufacture of transformer cores. The grades of these steels begin with the letter E (E1100), which means electrical low-carbon. The first number is the degree of alloying of the steel; the second is the guaranteed electrical and magnetic properties of steel; the third (number "0") - cold-rolled steel, textured; the fourth (number "0") - cold-rolled steel, low-textured. The higher the number, the higher the quality of the steel.

The additional letter P indicates increased strength and finish of the steel, the letter A at the end of the grade indicates that this grade of electrical steel has a particularly low specific loss.

For better orientation in the choice of a particular steel in the table. 1 shows data on the use of some steel grades.

Table 1

Certain steel grades

Steel grade	Name	Treatment types	Applications
Art.0	Common grade carbon	Soldering, welding	Wire, mesh, etc.
Art.3, Art.4	Same	Same	Welded structures, forging tools
08kp	Carbon high quality	Welding, stamping, bending	Lightly loaded parts
10kp	Same	Same and deep drawing	Same
15.15kp, 20.20kp	Same	Same	Medium strength fasteners
30.35	Same	Tempered	Medium abrasion parts
40	Same	Quenched and Tempered	Same
45,50,55	Same	Same	Heavy-duty abrasion parts
60G, 65G, 70G	Same, with higher manganese content	Same	Wear-resistant parts with spring properties
P, N, V ​​	Spring loaded	Cold winding	Springs, spring washers, etc.
А12, А15	Automaton	All heat treatments	Low stress parts with high strength surface
U7, U7A	Carbon, tool steel	Same	Hammers, chisels, screwdrivers, brands
У8, У8А	Same	Same	Chisels, metal saws, carpentry tools, punches, dies
U9, U9A, U10, U10A	Same	Same	Taps, dies, reamers, cutters, stamps
U12, U12A, U13	Same	Same	Drills, files, countersinks, scrapers, measuring tools
65, 75, 85, 60C2, 70C3, 65C2B, 50XB,50HG, 55SG, 60SG	Same	Same	Springs, springs, torsion bars
X12, X12M, X09	Alloy, instrumental	Same	Light duty cutting tool, measuring tool
9X, X05	Same	Same	Taps, drills, dies, reamers, cutters, countersinks, files
7ХЗ, 8ХЗ	Same	Same	High sliding speeds and impact loads
6XC, 9XC	Same	Same	Cutters, drills, taps, reamers, dies for cold forming
ХВ5,4Х8В2	Same	Same	Tools for hard metals
Р9, Р9Ф5, Р9К10, Р10К5Ф5, Р14Ф4, Р18	Same, high speed	Same	Same

It is important to know the grades of steels used in the manufacture of the most common tools. Sometimes from a tool that has become unusable, you can make a new, necessary one. Below is a list of steel grades used for the manufacture of some tools:

• hand saw blades - U8-U10
• hacksaw blades - P9
• blades for cutting rails - ШХ15
• circular saw blades - 85HF
• files - У10-У13, ШХ6
• rasps - U7, U7A
• needle files - U10-U12
• manual reamers - P9, 9XC
• machine reamers - P9, P18
• taps - Р9, Р18, 9ХС
• drills, cutters - P9, P18

For example, steel 18ХГТ contains,%: 0.17-0.23 С; 1.0-1.3 Cr, 0.8-1.1 Mn, about 0.1 Ti;

The grade of stainless steel 14X19H9A is deciphered as follows: steel contains 0.14% carbon, 0.19% chromium, 0.09% nickel, has a reduced content of harmful impurities (sulfur and phosphorus).

The grade of alloyed tool steel 3X2B8 is deciphered as follows: steel contains about 0.3% carbon, about 2% chromium and about 8% tungsten.

The grade of alloyed constructional steel 18X2H4VA is deciphered as follows: carbon about 0.18%, chromium about 2%, nickel about 4%, tungsten about 1% (marking rule for all steels: if the numbers after the letter denoting an alloying additive is not worth it, then this additive in steel contains about 1%), the steel has a reduced content of harmful impurities.

Table 2

Additions to high-grade and extra-high grade steels

addition to the steel grade	Initial processing	Subsequent remelting
VD	Vacuum Arc Remelting	-
VI	Vacuum induction melting	-
id	Same	Vacuum arc
UI	Same	Plasma Arc
ISH	Same	Electroslag
IL	Same	Electron Beam
ГР	Oxy-fuel refining	-
P	Plasma arc remelting	-
PT	Plasma Melting	-
PD	Same	Vacuum arc
PL	Same	Electron Beam
PP	Same	Plasma Arc
PN	Same	Electroslag
US	Synthetic slag treatment	-
W	Electroslag remelting	-
ШД	Same	Vacuum arc
SHL	Same	Electron Beam
SHP	Same	Plasma Arc
EL	Electron beam remelting	-

Steel 38KHN3MFA (%) - 0.33-0.40 С; 1.2-1.5 Cr; 3.0-3.5 Ni; 0.35-0.45 Mo; 0.1-0.18 V; steel ZOHGSA - 0.32-0.39 C; 1.0-1.4 Cr; 0.8-1.1 Mn; 1.1-1.4 Si.

In tool steels, a number is put at the beginning of the steel grade designation, indicating the carbon content in tenths of a percent. The starting figure is omitted if the carbon content is about 1% or more.

For example, steel 3X2V8F contains,%: 0.3-0.4 C; 2.2-2.7 Cr; 7.5-8.5 W; 0.2-0.5 V; 5ХНМ steel - 0.5-0.5 С; 0.5-0.8 Cr; 1.4-1.8 Ni; 0.19-0.30 Mo; CVG - 0.90-1.05 C; 0.9-1.2 Cr; 1.2-1.6 W; 0.8-1.1 Mn.

The designation of the bearing steel grade includes: the letter "Ш" and the letters denoting alloying elements. Behind the letter "X" (alloyed with chromium), figures are given corresponding to the mass fraction of chromium in tenths of a percent (for example, ShKh15, ShKh15SG, ShKh20SG).

The letter "A" at the end of the grade of any steel indicates that the steel belongs to the high-quality category (30KhGSA, U7A), in the middle of the grade designation - that the steel is alloyed with nitrogen (16G2AF), in the beginning of the brand - that automatic steel with increased machinability (A35G). The letters АС at the beginning of the brand indicate that the steel is automatic with lead (АС35Г2).

High-quality steel is indicated by adding the letter “Ш” or other letters through a dash at the end of the grade (Table 2). This means that the steel has undergone electroslag remelting, which ensures effective purification from sulfides and oxides.

At the end of the structural steel grade there may be additional letter designations: PP - low hardenability steel, L - foundry, K - steel for boilers, etc.

Construction steel is denoted by the letter "C" (construction) and numbers, conventionally corresponding to the yield strength of rolled products. The letter "K" at the end of the grade is a variant of the chemical composition of steel from tohigher corrosion resistance in the atmosphere, and the letter "T" - heat-strengthened rolled products (for example, S245, S345T, S390K).

When marking electrical steels (1211, 1313, 2211, etc.), the first number indicates the structural state and type of rolling, the second indicates the silicon content, and the third indicates hysteresis losses , the fourth is a group according to the main standardized characteristic. Together, the first three digits indicate the type of steel, and the fourth - the serial number of this type of steel.

For the manufacture of wide-gauge rails of types P75, P65, P50, steels of grades M76, M74 are used, where the letter "M" indicates the open-hearth smelting method, and the numbers indicate the average carbon content in hundredths percent.

The designation of the high speed steel grade includes: the letter "P", a number indicating the average mass fraction of tungsten in percent. In all high-speed steels, the mass fraction of chromium is about 4%, therefore, the letter "X" is not indicated in the designation of the brand. Vanadium, the mass fraction of which in various brands ranges from 1 to 5%, is denoted by the letter "F" in the brand if its average mass fraction is more than 2.5%.

The mass fraction of carbon in the brand designation of high speed steel is not indicated, since it is proportional to the mass fraction of vanadium. If high-speed steel is alloyed with molybdenum or cobalt, their mass fraction is indicated in the grade. For example, high-speed steel containing,%: 1.0-1.1 C; 3.0-3.6 Cr; 8.5-9.6 W; 2.1-2.5 V; 7.5-8.5 Co; 3.8-4.3 Mo, designate P9M4K8.

Non-standard alloy steels produced by the Elektrostal plant are designated by a combination of letters EI (research electric steel) or EP (trial electric steel). Alloy steel produced by the Zlatoust Metallurgical Plant is marked with the letters ZI, and by the Dneprospetsstal plant - DI. In all cases, after the combination of letters, there is a serial number of steel, for example, EI 417, EP 767, ZI 8, DI 8, etc. After the development of the brand by metallurgical and machine-building plants, the conventional designations are replaced by the generally accepted marking reflecting the chemical composition of the steel.

Cast steels are marked with the same alphanumeric system as wrought steels, but the letter L is added at the end of the grade, which means cast steel.

Tin, depending on the purpose, surface quality and properties, is divided into grades ChZhK, ChZhR, GZhG, GZhR, EZhK, EZhK-D, EZhR and EZhR-D. Letters in the designation of brands mean ZhK - canning tin, ZhR - tin for various purposes, except for food containers, H - black, G - hot tinning, E - electrotechnical tinning, D - tin with differential coating.

Features of steel marking in US standards

In accordance with the national ASTM (American Society for Testing and Materials) and SAE (Society Automotive Engineers) standards, the USA has adopted a digital marking system for structural steels, which in some cases adds letters ... Most steels, with the exception of corrosion-resistant and heat-resistant steels, are marked with a four-digit number. The first number indicates the main alloying element, the second - its percentage, the third and fourth correspond to the carbon content in hundredths of a percent. The first number 1 is adopted to denote carbon steels, in this case the second number is 0. For example, steel according to ASTM-SAE grade 1015 corresponds to steel grade 15 according to the Russian standard, and 1045 corresponds to grade 45.

The first digit 2 corresponds to alloyed Ni steels, digit 3 - Ni and Cr; 4 - Mo, Mo and Cr, Mo, Cr and Ni; 5 - Cr; 6 - Cr and V; 7 - Cr and W; 8 - Ni, Cr and Mo; 9 - also Ni, Cr and Mo.

Thus, steel grade 5140 according to ASTM-SAE corresponds to Russian steel grade 40X, and steel 8625 alloyed with Ni-Cr-Mo contains,%: 0.23-0.28 C; 0.4-0.7 Ni; 0.4-0.6 Cr; 0.15-0.25 Mo; 0.15-0.35 Si; 0.7-0.9 Mn; 0.035 R; 0.040 S.

The notation system according to AISI-SAE, according to the "Handbook of Metals", published by Rubin, is shown in Table 3.

If the steel must provide the required hardenability, then the letter H is placed after the numbers, for example 8625Н. Smelting steel in electric furnaces is indicated by the letter E, located in front of the numbers. In the case of microalloying with boron, the letter B is placed between the first and second pair of numbers, for example, 94B15. Ball bearing steels are marked with a five-digit number, in which the last three digits correspond to the chromium content in hundredths of a percent.

The chemical compositions of some steels used in the USA are presented in table. 3-6

Table 3

AISI-SAE notation

Numbers and numbers	Steel type and nominal alloying elements,%
Carbon steels
10xx (a)	No Alloy (Mn 1.00 max)
11xx	Sulfur
12xx	Sulfur and phosphorous
15хх	No alloying (max Mn content 1.00-1.65)
Manganese
13xx	Mn 1.75
Nickel
23xx	Ni 3.50
25xx	Ni 5,00
Nickel chrome
31xx	Ni 1.25; Cr 0.65 and 0.80
32xx	Ni 1.75; Cr 1.07
33xx	Ni 3.50; Cr 1.50 and 1.57
34xx	Ni 3.00; Cr 0.77
Molybdenum
40xx	Mo 0.20 and 0.25
44xx	Mo 0.40 and 0.52
Chromolybdenum
41xx	Cr 0.50, 0.80 and 0.95; Mo 0.12, 0.20, 0.25 and 0.30
Nickel-chromium-molybdenum
43xx	Ni 1.82; Cr 0.50 and 0.80; Mo 0.25
43BVхх	Ni 1.82; Cr 0.50; Mo 0.12 and 0.25; V 0,03 min
47xx	Ni 1.05; Cr 0.45; Mo 0.20 and 0.35
81xx	Ni 0.30; Cr 0.40; Mo 0.12
86xx	Ni 0.55; Cr 0.50; Mo 0.20
87хх	Ni 0.55; Cr 0.50; Mo 0.25
88хх	Ni 0.55; Cr 0.50; Mo 0,35
93хх	Ni 3.25; Cr 1.20; Mo 0.12
94хх	Ni 0.45; Cr 0.20; Mo 0.20
97хх	Ni 0.55; Cr 0.20; Mo 0.20
98хх	Ni 1.00; Cr 0.80; Mo 0.25
Nickel-Molybdenum
46xx	Ni 0.85 and 1.82; Mo 0.20 and 0.25
48xx	Ni 3.50; Mo 0.25
Chromium
50xx	Cr 0.27, 0.40 and 0.65
51xx	Cr 0.80, 0.87, 0.92 1.00 and 1.05
50xxx	Cr 0.50
51xxx	Cr 1.02; C - 1.00 min
52xxx	Cr 1.45
Chrome vanadium
61xx	Cr 0.60, 0.80 and 0.95; V 0.10 and 0.15 min
Chromium Tungsten
72xx	W 1.75; Cr 0.75
Silicon Manganese
92xx	Si 1.40 and 2.00; Mn 0.65, 0.82 and 0.85; Cr 0.00 and 0.65
High strength low alloy
9xx	Various SAE grades
Boron steels
xxBxx	B - means steel with boron

Note. xx (a) - in the last 2 digits of this designation - carbon content in hundredths of a percent

Table 4

Chemical composition of US structural steels

Steel grade	Content of elements,%
	C	Si	Mn	P	S		Cr	Mo	Ni
				no more
1010	0.08-0.13	0.20-0.35	0.30-0.60	0.04		0.05	-	-	-
1020	0.17-0.24	0.20-0.35	0.30-0.60	0.04		0.05	-	-	-
1034	0.31-0.39	0.20-0.35	0.50-0.80	0.04		0.05	-	-	-
1045	0.42-0.51	0.20-0.35	0.60-0.90	0.04		0.05	-	-	-
1060	0.54-0.66	0.20-0.35	0.60-0.90	0.04		0.05	-	-	-
1070	0.64-0.76	0.20-0.35	0.60-0.90	0.04		0.05	-	-	-
4130	0.28-0.33	0.20-0.35	0.40-0.60	0.04		0.04	0.80-1.10	0.15-0.25	-
4150	0.48-0.53	0.20-0.35	0.80-1.05	0.04		0.04	0.80-1.10	0.15-0.25	-
5145	0.43-0.48	0.20-0.35	0.70-0.90	0.04		0.04	0.70-0.90	-	-
51100	0.95-1.10	0.20-0.35	0.25-0.46	0.025		0.025	0.90-1.15	-	-
8620	0.18-0.23	0.20-0.35	0.70-0.90	0.04		0.04	0.40-0.60	0.15-0.25	0.40-0.70
8650	0.48-0.53	0.20-0.35	0.75-1.00	0.04		0.04	0.40-0.60	0.15-0.25	0.40-0.70
9310	0.08-0.13	0.20-0.35	0.45-0.65	0.025		0.025	1.00-1.40	0.08-0.15	3.00-3.50

Table 5

Chemical composition of US tool steels

Steel grade	Content of elements,%
	C	Si	Mn	Cr	Mo	V	W
H11	0.35	1.00	0.30	5,00	1.50	0.40	-
M3	1.15	0.30	0.30	4,00	5.25	3.25	5.75
T1	0.70	0.30	0.30	4.10	-	1.10	18,00
W1-0,8C Commercial	0.70-0.85	& lt; 0,35	& lt; 0,35	& lt; 0.20	-	-	-
W1-1,0C Extra	0.95-1.10	& lt; 0,35	& lt; 0,35	-	-	-	-
W1-1,2C Standard	1.10-1.30	& lt; 0,35	& lt; 0,35	& lt; 0.15	-	-	-
W2-0,9C-V Commercial	0.85-0.95	& lt; 0,35	& lt; 0,35	& lt; 0.20	-	0.15-0.35	-
W2-1,0C-V Extra	0.95-1.10	& lt; 0,35	& lt; 0,35	-	-	0.15-0.35	-
W2-1,0C-V Standard	0.95-1.10	& lt; 0,35	& lt; 0,35	& lt; 0.15	-	0.15-0.35	-

& nbsp;

Table 6

Chemical composition of US corrosion and heat resistant steels

Steel grade	Content of elements,%
	C	Si	Mn	S	P	Cr	Ni	Mo	Others
				no more					& nbsp;
301	& lt; 0.15	& lt; 1.00	& lt; 2.00	0,030	0,045	16.0-18.0	6.0-8.0	-	-
302	& lt; 0.15	& lt; 1.00	& lt; 2.00	0,030	0.045	17.0-19.0	8.0-10.0	-	-
304	& lt; 0.08	& lt; 1.00	& lt; 2.00	0,030	0.045	18.0-20.0	8.0-12.0	-	-
309	& lt; 0.20	& lt; 1.00	& lt; 2.00	0,030	0.045	22,0-24,0	12.0-15.0	-	-
430	& lt; 0.12	& lt; 1.00	& lt; 1.00	0,030	0,040	14,0-18,0	-	-	-
446	& lt; 0.20	& lt; 1.00	& lt; 1.50	0,030	0,040	23,0-27,0	-	-	N & lt; 0.25
501	& gt; 0.10	& lt; 1.00	& lt; 1.00	0,030	0,040	4.0-6.0	-	0.40-0.65	-

& nbsp;

Examples of marking analogs of structural alloy steels in the CIS and the USA

Steel	CIS	USA
Chrome	20X 35X	5120, 5120H 5135, 5135H
Chromoly	30XM 35XM	4130, 4130H 4135, 4135H
Nickel-Molybdenum	15H2M (15HM) 20H2M (20HM)	4615 4620, 4620Н
Nickel Chrome	12Х2Н4А	Е3310
Chromium-Nickel-Molybdenum	20ХН2М (20ХНМ) 40ХН2МА (40ХНМА)	4320, 4329Н 4340
Chrome-manganese-nickel with molybdenum	20ХГНМ 40ХГНМ	8620, 8620Н 9840

Corrosion-resistant and heat-resistant steels are marked with a three-digit number, in which the first digit corresponds to steels of the following alloying systems: 2xx - Cr-Mn-Ni with nitrogen ; 3xx for Cr-Ni; 4xx - Cr; 5xx for Cr-Mo; 6xx - Cr-Ni-Mo, as well as Cr-Mo, with other alloying materials.

For example, steel grade 202 contains,%: 0.15 C, 17-19 Cr, 7.5-10.0 Mn, 4-6 Ni, 0.25 N ; grade 304,%: 0.15 C, 18-20 Cr, 8-10.5 Ni.

Steel markings in Germany

According to DIN (Deutsche Industrienorm) in Germany, the alphanumeric marking system is carried out in accordance with the classification of steels by the degree of alloying and heat treatment modes. The German national standard carries out labelingsteels in two ways.

The first method - using numbers indicating the material number. The first digit characterizes the method of steel production: 0 - the method does not play a role or is not defined; 1 - Thomas boiling steel; 2 - Thomas calm steel; 3 - boiling steel of a different production method; 4 - calm steel of a different production method; 5 - boiling open-hearth steel; 6 - calm open-hearth steel; 7 - boiling oxygen-converter steel; 8 - calm oxygen-converter steel; 9 - electrofusion steel.

The second digit characterizes the processing characteristics of steel: 0 without processing or condition after rolling or forging; 1 - after normalization, 2 - after softening annealing; 3 - after annealing in order to improve the machinability by cutting; 4 - after annealing to increase the viscosity; 5 - after improvement; 6 - after quenching; 7 - after cold deformation; 9 - after special processing.

The steels are classified as follows.

Ordinary and structural steels

00. Commercial and low grade.
01. Conventional unalloyed with less than 0.30% carbon.
02. Conventional constructional unalloyed with carbon content less than 0.30%.
03. High quality unalloyed with carbon content less than 0.10%.
04. High quality unalloyed with a carbon content of over 0.1% to 0.30%.
05. High quality unalloyed with a carbon content of over 0.30% to 0.60%.
06. High quality unalloyed with a carbon content of over 0.60%
07. High quality unalloyed with high phosphorus and sulfur content.
08. High quality alloyed with carbon content less than 0.30%.

Improvable steels, non-alloy steels

10. Steel with special physical properties.
11. Structural ones with a carbon content of less than 0.50%.
12. Structural ones with a carbon content of more than 0.50%.
13, 14.
15. Instrumental, 1st quality group.
16. Instrumental, 2nd group of quality.
17. Instrumental, 3rd group of quality.
18. Tool steels for special purposes.
19.

Alloy, tool steels

20. Cr.
21. Cr-Si. Cr-Mn, Cr-Mn-Si.
22. Cr-V, Cr-V-Si, Cr-V-Mn, Cr-V-Si.
23. Cr-Mo, Cr-Mo-V.
24. W, Cr-W.
25. W-V, Cr-W-V.
26. W except for classes 25, 25, 27.
27. Steel with nickel.
28. Other alloys.
29.

Miscellaneous steels

30, 31.
32. High speed cobalt.
33. Cobalt-free high speed cutting.
34. Wear resistant.
35. Ball bearing.
36. Iron materials with special physical properties, alloys with special magnetic properties without cobalt, except for Ni - A1 alloys.
37. Iron alloys with special physical properties, alloys with special magnetic properties with cobalt and Ni - A1 alloys.
38. Iron materials with special physical properties, other alloys are Ni-free.
39. Iron materials with special physical properties, other alloys with Ni.

Chemical resistant

40. Corrosion-resistant steels with 2% Ni without molybdenum and special additives.
41. Corrosion-resistant steels with 2% Ni with molybdenum and special additives.
42.
43. Corrosion-resistant steels with 2% Ni without molybdenum and special additives.
44. Corrosion-resistant steels with 2% Ni with molybdenum and special additives.
45. Corrosion-resistant steels with 2% Ni and special additives.
46.
47. Heat resistant with Ni less than 2%.
48. Heat resistant with Ni more than 2%.
49. High temperature materials.

Structural steel < / p>

50. Mn-Si-C.
51. Mn-Si, Mn-Cr.
52. Mn-Cu, Mn-V, Si-V, Mn-Si-V.
53. Mn-Ti, Si-Ti, Mn-Si-Ti, Mn-Si-Zr.
54. Mn (including Mn, Si), Nb, Ti, V, W, Cr-W, Cr-V-W.
55.
56. Ni.
57. Cr-Ni with at least 1% chromium.
58. Cr-Ni with chromium content over 1 to 1.5%,
59. Cr-Ni with a chromium content of over 1.5 to 2%.
60. Cr-Ni with chromium content exceeding 2 to 3%.
61.
62. Ni-Si, Ni-Mn, Ni-Cu.
63. Ni-Mo, Ni-Mo-Mn, Ni-Mo-V, Ni-V-Mn, Ni-Cu-Mo.
64.
65. Cr-Ni-Mo with less than 0.4% molybdenum and less than 2% nickel
66. Cr-Ni-Mo with a molybdenum content of less than 0.4% and a nickel content of more than 2% and less than 3.5%.
67. Cr-Ni-Mo with a molybdenum content of less than 0.4% and a nickel content of more than 3.5% and less than 5%.
68. Cr-Ni-V, Cr-Ni-W, Cr-Ni-V-W.
69. Cr-Ni except for classes 57-68.
70. Cr.
71. Cr-Si, Cr-Mn, Cr-Si-Mn.
72. Cr-Mo with molybdenum content less than 0.35%.
73. Cr-Mo with a molybdenum content of more than 0.35%.
74.
75. Cr-V with less than 2% chromium.
76. Cr-V with more than 2% chromium.
77. Cr-Mo-V.
78.
79. Cr-Mn-Mo, Cr-Mn-Mo-V.
80. Cr-Si-Mo, Cr-Si-Mn-Mo,
Cr-Si-Mo-V, Cr-Si-Mn-Mo-V.
81. Cr-Si-V, Cr-Mn-V.
82. Cr-Mo-W, Cr-Mo-WV.
83.
84. Cr-Si-Ti, Cr-Mn-Ti, Cr-Si-Mn-Ti.
86. Nitrided.
90-99. Special views.

Second way - notation using letters and numbers. This type provides for the designation of steels by the degree of alloying and the type of heat treatment.

Carbon unimprovable steels. At the beginning of the grade there is a capital letter indicating the type of steel deoxidation: U - boiling steel; R - semi-calm or calm steel, deoxidized with manganese and silicon; RR - steel deoxidized with silicon, manganese and aluminum using a special technology.

This is followed by the St index and a three-digit number that characterizes the minimum ultimate strength at room temperature in N / mm ². Further, the number of the quality group is indicated, which can be 1, 2 and 3, while group 3 differs from groups 1 and 2 by a lower content of phosphorus, sulfur and carbon. A hyphen is placed between the tensile strength and the quality group. These four designations form the basis of the brand, however, additional information is also possible. The letters, which are placed at the very beginning of the brand, indicate the method of smelting: E ​​- steel for electric smelting; M - steel smelted in an open-hearth furnace; V - steel smelted using oxygen blowing.

A capital Z between the first and second designator indicates the drawability of the steel. In cases where steel can be stamped or forged, the letter P is placed between the first and second designations.

Steel for pipe production is designated by the letters Ro, which are also located between the first and second designations.

Steel delivered in rolling condition is marked with a U at the end of the grade and an N after normalization.

Carbon quality steels. This class of steels is marked with the letter C at the beginning of the designation, followed by a number reflecting the carbon content multiplied by 100.

Carbon tempering steels are marked with Ck at the beginning of the designation, followed by a number representing the carbon content multiplied by 100.

Low alloy quality steels are marked at the beginning with a number corresponding to the carbon content of the steel multiplied by 100; then the chemical symbols of the most important alloying elements are indicated; then - the numbers corresponding to the content of the elements, multiplied by the coefficient given below:

Cr, Co, Mn, Ni, Si, W Al, Cu, Mo, Ti, V P, S, N

4 10 100

High alloy steels are marked with an X at the beginning of the designation, followed by the number corresponding to the carbon content multiplied by 100; hereinafter - chemical symbols of the most important alloying elements and numbers reflecting the average content of alloying elements.

Steels for special applications

Mild carbon steels for cold rolled strip are marked with the letters St at the beginning of the designation, followed by numbers from 0 to 4, corresponding to the purity of the steel (in terms of content restrictions sulfur and phosphorus).

Ageless steels are marked at the beginning of the designation with the letter A, followed by the letters St, then the numbers corresponding to the minimum guaranteed tensile strength

Wire rod steels are marked with a D at the beginning of the designation, followed by a number corresponding to the carbon content.

Boiler plate steels are marked with the letter H at the beginning of the designation. followed by Roman numerals from I to IV, reflecting the content of carbon and manganese.

Soft magnetic steels are marked with the letter R at the beginning of the designation, followed by the chemical symbol of the main element (iron, silicon or nickel), then -numbers corresponding to the magnitude of the coercive force in N / cm multiplied by 100.

Dynamo and transformer steels are marked with a Roman numeral (from I to IV) and a number reflecting the amount of losses (W / kg).

Casting steels are marked with GS at the beginning of the designation, followed by a marking similar to carbon, low alloy, tempering, high carbon steels.

Examples of marking analogs of structural alloy steels in the CIS and Germany

Steel	CIS	Germany
Chrome	20X 35X	20Cr4 34Cr4
Chromoly	30XM 35XM	25CrMo4 34CrMo4
Manganese	40G 30Г2	40Mn4 28Mn6
Chromomanganese	18XG	20MnCr5
Chromium-Nickel-Molybdenum	38Х2Н2МА (38ХНМА)	36CrNiMo4
Chromoaluminum with molybdenum	38Х2МЮА (38ХМЮА)	41CrAlMo7

Japanese Industrial Standard (JIS) steels

Structural steel grades are formed from several uppercase letters and a single, two-digit, or three-digit number.

1. Carbon steels SSxxx, where xxx is a three-digit number indicating the minimum tensile strength (MPa), for example SS140.
2. Carbon steel of guaranteed chemical composition SxxC, where xx is a two-digit number indicating the average carbon content in hundredths of a percent multiplied by 100, for example S20C (average carbon content 0.20%).
3. Free-cutting steel SUMx, where x is a single-digit number indicating the serial number of the steel in the group.
4. Carbon steel for forgings SFxxx, where xxx is a three-digit number representing the minimum tensile strength (MPa), for example SF420.
5. Reinforcing steel SSDxxx and SRDxxx, where xxx is a three-digit number representing the minimum tensile strength. The middle letters S and R represent the location of the ribs on the surface of the reinforcing steel.
6. Carbon Steel for SVxx rivets, where xx is a two-digit number representing the minimum tensile strength.
7. Carbon steel for SBC chains.
8. Steel for hot-rolled sheet SPNx, where x is the serial number of the steel in the group.
9. Steel for cold-rolled sheet SNCx, where x is the serial number of the steel in the group.
10. Steel for SPMx cold rolled strip, where x is a capital letter denoting the degree of hardening.
11. Spring steel for SKx cold rolled strip, where x is the serial number of the steel in the group.
12. Steel for wire rod SMRMx, where x is the serial number of the steel in the group.
13. High pressure steel STPxxx, where xxx is a three-digit number indicating the minimum tensile strength (MPa).
14. Steel for high pressure pipes STSxxx. where xxx is a three-digit number indicating the minimum tensile strength (MPa).
15. Carbon steel for boiler tubes STBxxx, where xxx is a three-digit number indicating the minimum tensile strength (MPa).
16. Steel for boiler tubes of STL locomotives.
17. Alloy steel for STBAxx boiler pipes, where xx is a two-digit number indicating the grade of steel.
18. Steel for pipes used in the chemical industry, STCxxx, where xxx is a three-digit number indicating the ultimate strength (MPa).
19. Carbon Steel for Structural Pipes, STKxxx, where xxx is a three-digit number indicating the minimum tensile strength (MPa).
20. Alloy steel for pipes used in structures, STKSx, where x is a number indicating the grade of steel.
21. Steel for pipes operating at low temptemperature, STBLxxx, where x is a three-digit number indicating the minimum tensile strength (MPa).
22. Spring steel SUPx, where x is the serial number of the steel in the group.
23. SUSx ball bearing steel, where x is the serial number of the steel in the group.
24. Nickel-chromium tempered structural steel SNCx, where x is the serial number of the steel in the group.
25. Nickel-chromium case-hardened structural steel SNCxx, where xx is a two-digit number indicating the serial number of the steel in the group.
26. Nickel-chromium-molybdenum improved structural steel SNСМх, where x is the serial number of the steel in the group.
27. Nickel-chromium-molybdenum case-hardened structural steel SNСМхх, where xx is a two-digit number indicating the serial number of the steel in the group.
28. Chromium tempered structural steel SCrx, where x is the serial number of the steel in the group.
29. Chromium case-hardened structural steel SCrxx, where xx is a two-digit number indicating the serial number of the steel in the group.
30. Chromomolybdenum tempering structural steel SCMx, where x is the serial number of the steel in the group.
31. Chromo-molybdenum case-hardened structural steel SCMxx, where xx is a two-digit number indicating the serial number of the steel in the group.
32. Aluminum-chromium-molybdenum nitrided steel SACM.
33. Corrosion-resistant steel SUSx, where x is the serial number of the steel in the group.
34. Heat-resistant steel SUHx, where x is the serial number of the steel in the group.

Examples of marking analogs of structural alloy steels in the CIS and Japan

Steel	CIS	Japan
Chrome	30X 40X	SCr430, SCr430H SCr440, SCr440H
Manganese	30Y2 40Y2	SMn433, SMn433H SMn438, SMn438H
Chromoly	15XM 35XM	SCM415, SCM415H SCM435, SCM435H
Nickel Chrome	20ХН2М (20ХНМ) 40ХН2МА (40ХНМА)	SNCM420, SNCM420H SNCM439
Chrome aluminum with molybdenum	38Х2МЮА (38ХМЮА)	SACM645

Marking for corrosion-resistant steels

Corrosion-resistant steels are a group of high-alloy steels (Table 7).

In the CIS, these steels are supplied in accordance with GOST 5632-72 and TU. Marking is carried out in accordance with the alphanumeric system adopted for alloy steels. The difference is that many austenitic steel grades indicate the maximum carbon content rather than the average carbon content. This is due to the effect of carbon on corrosion resistance

Table 7

Marking for corrosion-resistant steels

CIS	US	Germany	Japan
Ferritic steels
08X17 12X17 12X17E 15X25	430 430F (+0.6 Mo) 430FSe (Se & gt; 0.15) 446 (up to 0.25 Ni)	X8Cr17 X12CrMoS17 X12CrMoS17 -	SUS430 SUS430F - SUH446
Martensitic steels
12X13 A12X13 20X13 20X17H2 65X18 85X18 110X18	403 410 416 (S 0.15) 420 431 440A < br /> 440B 440C	X10Cr13 X10Cr13 X12CrS13 X20Cr13 X22CrNi17 X65CrMo14 X90CrMoV18 X105CrMo17	SUS403 SUS410 SUS416 SUS420 SUS431 SUS440A SUS440B SUS440C
Chromium-Nickel Austenitic Steels
- 12Х18Н9 08Х18Н10 03Х19Н10 20Х22Н13 25Х25Н20С2	301 (16-18 Cr; 6-8 Ni) 302 (17-19 Cr; 8-10 Ni; & lt; 0.15 C) 304 (0.08 C; 18-20 Cr; 8-12 Ni) 304L (0.03 C; 18-20 Cr; 8-12 Ni) 309 ( 22-24 Cr; 12-15 Ni; 0.20 C) 310 (0.25 C; 24-26 Cr; 19-22 Ni)	X12CrNi177 X12CrNi188 X5CrNi189 X5CrNi189 X15CrNiSi2012 X15CrNiSi2520	SUS301 SUS302 SUS304 SUS304L SUS309 SUH310
Chromium-Nickel Austenitic Steels
08Х17Н12М2 03Х17Н12М2 08Х18Н10Т 08Х18Н11Б	316 (0.08 C; 16-18 Cr; 10-14 Ni; 2-3 Mo) 316L (0.03 C; 16-18 Cr; 10-14 Ni; 2-3 Mo) 321 (0.08 C; 17-19 Cr; 9-12 Ni; Ti & gt; 5C) 347 (0.08 C; 17-19 Cr; 9-13 Ni - [Nb + Ta & gt; 10 C])	X5CrNiMo1810 X2CrNiMo1810 X10CrNiTi189 X10CrNiNb189	SUS316 SUS316L SUS321 SUS347
Manganese austenitic steels
- 12Х17Г9АН4	201 (0.15 C; 7.5 Mn; 16-18 Cr; 3.5-5.5 Ni; 0.25 N) 202 (0.15 C; 10 Mn; 16-18 Cr; 4-6 Ni; 0.25 N)	- X8CrMnNi189	SUS201 SUS202

In Germany, according to the DIN 17440 standard, the letter "X" is introduced in the designation of grades of corrosion-resistant steels before the numbers corresponding to the carbon content. The carbon content is indicated by a two-digit number (in rare cases, a three-digit number, when the mass fraction of carbon in steel is more than 1%). This number is obtained by multiplying the carbon content by a factor of 100. Alloying elements in the grade are indicated by their symbols. Alloying elements (no more than three) are indicated in the grade in decreasing order of their content. After listing the alloying elements, the mass fractions of those elements in which they exceed 5% are given. For example, ferritic steel X12CrMoS17 contains 0.12% C, 17% Cr and is alloyed with small amounts of molybdenum and sulfur. Steel X12CrNiTi189 contains 0.12% C, 18% Cr, 9% Ni and Ti 5%. Its brand designation indicates the mass fractions of chromium and nickel only.

In the US, the AISI standard uses a digital coding system. Each corrosion-resistant steel has a three-digit number. The 200 series numbers are used for marking chromium-manganese and chromium-manganese-nickel austenitic steels. Series "300" characterizes chromium-nickel austenitic steels. The 400 series is used for marking ferritic and martensitic steels. If the letter “L” at the end of the grade is used in the brand designation of austenitic steel, this means that this steel contains especially little carbon (C & lt; 0.03%).

Japan and the UK use the US digital coding system. The difference is the additions to three-digit numbers. These additions indicate nationality.