Structural high-quality carbon steels GOST 1050 88. Long-rolled products, calibrated, with special surface finishing from high-quality carbon structural steel

Classification. By type of processing, rolled products are divided into: hot-rolled and forged; calibrated; with special surface finishing. -
Depending on the condition of the material, rolled products are produced: without heat treatment, heat treated - TO; cold-worked - NG (for calibrated rolled products and hard rolled products with special surface finishing).

Rolled products are produced in two surface quality groups:
2GP - mainly for hot pressure treatment; ,
ZGP - mainly for cold machining.

Steel grades: 08, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 58 (55pp), 60.
In the steel grade designation, the numbers indicate the average carbon content in hundredths of a percent.

The surface quality and requirements for cutting the ends of calibrated rolled products must comply with GOST 1051-73 groups B and C, with special surface finishing - GOST 14955-77 groups B, D and D.
The hardness (TB1) of long products without heat treatment should not exceed 255 HB; calibrated and with special surface finishing hardened - 269 NV.

Technical requirements. The mechanical properties and impact strength of rolled products are given in table. 3. Standards of Mechanical properties specified in table. 3, relate to rolled products with a diameter or thickness of up to 80 mm. For rolled products with a diameter or thickness over 80 mm, a reduction in the relative elongation by 2% and the relative contraction by 5% is allowed.
The macrostructure (MS) normalized in points is given in Table. 4.: The normalized mechanical properties (M2) of calibrated rolled products in the cold-worked or untreated state are given in table. 5.

3. Mechanical properties of rolled products in a normalized state (M1)

10 205 330 31 55 - 20 245 410 25 55 - 30 295 490 21 50 78 40 335 570 19 45 59 50 375 630 14 40 38 58 (55pp) 315 660 12 28 -

steel grade	Yield strength s t,MPa	Temporary resistance s in,MPa	Relative extension d 5, %	Relative narrowing Y%	Impact strength * KCU, J/cm 2
steel grade	no less
08	196	329	33	60	-
15	225	379	27	55	-
25	275	450	23	50	88
35	315	530	20	45	69
45	355	600	16	40	49
55	380	650	13	35	-
60	400	680	12	35	-
* Impact strength (IUV) of heat-treated (quenching + tempering) samples.

Notes:
1. Standards of mechanical properties given in table. 3, refer to rolled products with a diameter or thickness of up to 80 mm. For rolled products with a diameter or thickness over 80 mm, a reduction in relative elongation by 2% (abs.) and relative contraction by 5% (abs.) is allowed. Standards of mechanical properties for workpieces forged from rods with a diameter or thickness of over 120 to 250 mm for rolled products with a diameter or thickness of 90 to 100 mm must correspond to those given in Table. 3.
2. By agreement between the manufacturer and the consumer, for steel grades 25 - 60, a reduction in tensile strength by 20 MPa is allowed in comparison with the standards specified in Table. 3, while simultaneously increasing the elongation rates by 2% (abs.).

4 . Normalized macrostructure (RMS) of steel in points, no more

Central porosity	Point heterogeneity	Liquidation square	General spot eradication	General spot eradication	Shrink liquidation for rolled size		Subcortical vesicles	Intercrystalline cracks
					up to 70 mm	St. 70 mm
3	3	3	2	1	1	2	Not allowed
Note. For rolled products with a size of 70 mm or more with a surface quality of the ZGP group, subcortical bubbles of point 2 are allowed to a depth of no more than 1/2 of the tolerance for diameter or thickness.

5. Standardized mechanical properties (M2) of calibrated rolled products

15 8 45 340 23 55 25 7 40 410 19 50 35 6 35 470 15 45 45 6 30 540 12 40

steel grade	s in,MPa	Relative extension d 5, %	Relative extension d 5, %	Tensile strength s in,MPa	Relative extension d 5, %	Relative extension d 5, %
	Cold-hardened rolled products			Chilled or high-low rolled products
	No less
10	410	8	50	290	26	55
440
20	490	7	40	390	21	50
540
30	560	7	35	440	17	45
590
40	610	6	35	510	14	40
640
50	660	6	30	560	12	40

Rental range:
hot-rolled round grades 08-60 according to GOST 2590-88;
hot-rolled square - GOST 2591-88;
hot-rolled hexagonal - GOST 2879-88;
hot rolled strip -. GOST 103-76;
forged round and square - GOST 1133-71;
calibrated round - GOST 7417-75;
round with special surface finishing - GOST 14955-77.

Examples of symbols

Long-rolled products, round, of normal rolling accuracy (B), class II in curvature of unmeasured length (ND), with a diameter of 100 mm according to GOST 2590-88, made of steel grade. 30, with surface quality group 2GD. with mechanical properties according to (M1), with hardness according to (TV1), impact strength control according to (KUV), with deburring (US), with hot upset test (65), without heat treatment;

Circle

V - II - ND - 100 GOST 2590 - 88
30 - 2GP - M1 - TV1 - KUV - UZ - 66 GOST 1050 - 88

Rolled strip, normal rolling accuracy (B), sickle shape class 2, deviation from flatness class 2, multiple measured length (CD), thickness 3 mm, width 90 mm according to GOST 103-76, from steel grade 45, with surface quality of the ZGI group , with mechanical properties according to (M1)^ with hardness according to (TB1), with normalized hardening ability (HR), without heat treatment:

Calibrated rolled products, square, with a tolerance range of h11, a multiple of the measured length (CD), with a square side of 15 mm in accordance with GOST 8559-75, from steel grade 20, with surface quality of group B in accordance with GOST 1051-73, with mechanical properties in accordance with (MZ ), with hardness according to (TV2), ensuring weldability (GS), cold-worked (NG);

Examples of symbols that can be given in design documentation

Rolled products with special surface finishing: round, with tolerance range h11, unmeasured length (ND), diameter 8 mm, surface quality group B according to GOST 14955-77, made of grade 20 steel, with mechanical properties according to table. 5 (M2), about hardness according to, (TVZ), Cold-worked (NG):

Circle

h11 - ND - 8 GOST 14955 - 77
20 - V - M2 - TV3 - NG GOST 1050 - 88

5. Mechanical properties and hardness of hot-rolled and calibrated thermally untreated rolled carbon sulfur steel

25 550 - 700 19 35 315 500 - 650 21 35 - - - - 35 630 - 780 17 25 380 600 - 750 19 25 315 550 - 700 20 25 45 700 - 850 14 15 430 650 - 800 16 15 375 630 - 780 17 15 55 800 - 950 12 - 490 750 - 900 14 - 420 700 - 850 15 -

steel grade	Mechanical properties of rolled products
	up to 16 mm				from 16 to 40 mm				from 40 to 100 mm
	Yield strength s t,MPa		Relative extension d 5, %	Impact work KS, J	Yield strength s t,MPa	Tensile strength s in, MPa	Relative extension d 5, %	Impact work KS, J	Yield strength s t,MPa	Tensile strength s in, MPa	Relative extension d 5, %	Impact work KS, J
	no less		no less			Tensile strength s in, MPa	no less			Tensile strength s in, MPa	no less
375
30	400	600 - 750	18	30	355	550 - 700	20	30	295	500 - 650	21	30
430
40	460	650 - 800	16	20	400	630 - 780	18	20	355	600 - 750	19	20
490
50	520	750 - 900	13	-	460	700 - 850	15	-	400	650 - 800	16	-
550
60	580	850 - 1000	11	-	520	800 - 950	13	-	450	750 - 900	14	-
Notes: 1. Standards of mechanical properties before 01/01/92 are not rejected; determination is required. 2. The mechanical properties of steel 30 apply to rolled products up to 63 mm in size. 3. The values of mechanical properties are given for rolled products with a round section.

6. Standardized hardness, HB, rolled products

10 - 187 143 20 - 207 163 30 - 229 179 50 207 255 217 60 229 269 229

steel grade	Hot woven and forged rolled products		Rolled products calibrated and with special surface finishing
	without heat treatment	after annealing or high tempering	hard-worked	annealed or high tempered
	no more
08	131	-	179	131
143
15	149	-	197	149
163
25	170	-	217	170
179
35	207	-	229	187
40	217	187	241	197
45	220	197	241	207
241
55	255	217	269	229
255

Steel 20. Application in production.

The use of steel 20 in general engineering is widespread. Load-handling parts of cranes, various fingers, pipes, and replaceable elements of sliding bearings are made from this material. Pipeline fittings made from steel 20 are characterized by resistance to high operating pressure in pipelines.

We are interested in the “profile” use of steel 20. Some sources indicate that it is acceptable to manufacture worm gear elements from St 20, namely the worm. This is not an entirely true statement. In its “pure” form, this steel is not used in gearboxes. The manufacture of worms and gears for newly produced drive mechanisms from low-carbon steels, to which Steel 20 belongs, is allowed only if it contains alloying elements. The composition should contain chromium, manganese and molybdenum in larger proportions. If the part is produced for repair purposes, then it must undergo a carburization process, because steel 20, due to its original carbon content, does not hold hardening. But cementation requires expensive chemical-thermal equipment, which only specialized, highly specialized enterprises can afford.

In the mass production of drive mechanism parts, a strip of Steel 20 is used. Assembly units of drive roller chains, connecting and transition links are stamped from it. These products are small in size and do not require a large furnace chamber for carburizing.

Chemical composition of Steel 20.

For all carbon steels, the most significant is the percentage of carbon content in the total composition. This indicator is indicated on the brand in hundredths of a percent. The full chemical composition of Steel 20 will be as follows:

iron (Fe) - up to 98%;
carbon (C) - from 0.17 to 0.24%;
manganese (Mn) - from 0.35 to 0.65%;
nickel (Ni) - up to 0.25%;
sulfur (S) - up to 0.04%;
phosphorus (P) - up to 0.04%;
chromium (Cr) - up to 0.25%;
copper (Cu) - up to 0.25%;
arsenic (As) - 0.08%.

Steel 20 GOST.

The production of all the most important products from Steel 20 is regulated by the following standards (GOST):

long products, including shaped steel - GOST 1050-88, GOST 2590-2006, GOST 2591-2006, GOST 2879-2006, GOST 8509-93, GOST 8510-86, GOST 8240-97, GOST 8239-89;
calibrated rod - GOST 7417-75, GOST 8559-75, GOST 8560-78, GOST 10702-78;
polished rod and silver - GOST 14955-77;
thick sheet - GOST 1577-93, GOST 19903-74;
thin sheet - GOST 16523-97;
tape - GOST 6009-74, GOST 10234-77, GOST 103-2006, GOST 82-70;
wire - GOST 5663-79, GOST 17305-91;
forgings and forged blanks - GOST 8479-70;
pipes - GOST 10704-91, GOST 10705-80, GOST 8731-74, GOST 8732-78, GOST 8733-74, GOST 5654-76, GOST 550-75.

Steel 20. Mechanical properties.

Mechanical characteristics at elevated temperatures

Test temperature, °C	σ0.2, MPa	σВ, MPa	δ5, %	ψ, %	KCU, J/cm2
20	280	430	34	67	218
200	230	405	28	67	186
300	170	415	29	64	188
400	150	340	39	81	100
500	140	245	40	86	88
700		130	39	94
800		89	51	96
900		75	55	100
1000		47	63	100
1100		30	59	100
1200		20	64	100

Mechanical properties of Steel 20 at a temperature of +20C.

Regulatory document	Delivery status	σВ (MPa)	δ5 (%)	ψ (%)	HB (no more)
GOST 1050-74	Calibrated steel:
	hot-rolled, forged and silver steel of the 2nd category after normalization	410	25	55
	5th category after hardening	490	7	40
	5th category after annealing or high tempering	390	21	50
GOST 10702-78	Steel calibrated and calibrated with special finishing:
	after holiday or annealing	390-490		50	163
	after spheroidizing annealing	340-440		50	163
	cold-worked without heat treatment	490	7	40	207
GOST 1577-81	Normalized or hot-rolled strips	410	25	55
GOST 4041-71	Heat-treated sheet of category 1-2	340-490	28		127

Mechanical properties of forgings

Heat treatment	KP	Section, mm	σ0.2, MPa	σВ, MPa	δ5, %	ψ, %	KCU, J/m 2	HB, no more
Normalization	175	less than 100	175	350	28	55	64	101-143
	175	100-300	175	350	24	50	59	101-143
	175	300-500	175	350	22	45	54	101-143
	175	500-800	175	350	20	40	49	101-143
	195	less than 100	195	390	26	55	59	111-156
	195	100-300	195	390	23	50	54	111-156
	215	less than 100	215	430	24	53	54	123-167
	215	100-300	215	430	20	48	49	123-167
Hardening. Vacation	245	100-300	245	470	19	42	39	143-179

Mechanical properties of steel after chemical-thermal treatment.

Technological properties of Steel 20

Specific gravity		7.85 g/cm3
Material hardness	Steel 20 after annealing, GOST 1050-88	HB 10 -1 = 163 MPa
	Calibrated, cold-worked rod, GOST 1050-88	HB 10 -1 = 207 MPa
	Heat-treated sheet. GOST 4041-71	HB 10 -1 = 127 MPa
	Hot-deformed pipes, GOST 550-75	HB 10 -1 = 156 MPa
	Pipes, GOST 8731-87	HB 10 -1 = 156 MPa
	Thick annealed sheet, GOST 1577-93	HB 10 -1 = 156 MPa
Critical point temperature	Ac 1	735
	Ac 3 (Ac m)	850
	Ar 3 (Arc m)	835
	Ar 1	680
Forging temperature	started	1280
	end	750
	cooling	on air
Cutting machinability: in the hot-rolled state at HB 126-131 and δ B = 450-490 MPa		To υ TV. spl =1.7 and K υ b.st =1.6
Weldability of the material		without restrictions, except for parts after chemical-thermal treatment
Welding methods		RDS, ADS under flux and gas protection, KTS
Flock sensitivity		not sensitive
Tendency to temper brittleness		not inclined

Impact strength.

Impact strength KCU (J/cm3) at low temperatures °C

GOST	Delivery status	Section, mm	KCU at +20	KCU at -40	KCU at -60
19281-73	Long and shaped rolled products	from 5 to 10	64	39	34
		from 10 to 20 incl.	59	34	29
		from 20 to 100 incl.	59	34	-
19282-73	Sheets and strips	from 5 to 10	64	39	34
	Sheets and strips	from 10 to 60 incl.	59	34	29
	Sheets after quenching, tempering (Transverse samples)	from 10 to 60 incl.	-	49	29

Endurance limit

σ -1, MPa	J-1, MPa	δ5, MPa	σ 0.2,MPa	Heat treatment, steel condition
206		500	320
245		520	310
225		490	280
205	127			Normalization 910 C, release 620 C.
193		420	280
255	451			Cementation 930 C, hardening 810 C, tempering 190 C.

Physical properties of steel 20

Test temperature, °C	20	100	200	300	400	500	600	700	800	900
Modulus of normal elasticity, E, GPa	212	208	203	197	189	177	163	140
Modulus of elasticity under torsional shear G, GPa	78	77	76	73	69	66	59
Density, pn, kg/cm3	7859	7834	7803	7770	7736	7699	7659	7917	7624	7600
Thermal conductivity coefficient λ, W/(m °C)		51	49	44	43	39	36	32	26	26
Ud. electrical resistance, R, (p, NOm m)		219	292	381	487	601	758	925	1094	1135
Linear expansion coefficient, а, (10-6 1/°С)	12,3	13,1	13,8	14,3	14,8	15,1	15,2
Specific heat capacity, C, J/(kg °C)	486	498	514	533	555	584	636	703	703	695

Our catalog also contains descriptions and characteristics of other steel grades used in the production of drive chains and gearboxes.

Carbon structural quality steel gauged bars with special surface finish. General specifications

GOST 1050-88

OKP 09 5000, 11 4100, 11 5000

Date of introduction 01/01/91

This standard establishes general technical conditions for hot-rolled and forged long products from high-quality carbon structural steel grades 08, 10, 15, 20, 25,30, 35, 40, 45, 50, 55, 58 (55pp) and 60 with a diameter or thickness of up to 250 mm, as well as rolled calibrated and with special surface finishing of all brands.

In terms of chemical composition standards, the standard applies to other types of rolled products, ingots, forgings, stampings made of steel grades listed above, as well as steel grades 05kp, 08kp, 08ps, 10kp, 10ps, 11kp, 15kp, 15ps, 18kp, 20kp and 20ps .

1. MAIN PARAMETERS AND DIMENSIONS

1.1. The grades and chemical composition of steel according to the ladle sample must correspond to those given in Table 1.

Table 1

Continuation of the table. 1

Notes:

According to the degree of deoxidation, steel is designated: boiling - kp. semi-calm - ps, calm - without index.
Steel grade 05kp is not allowed for use in newly created and modernized equipment.
The profile for oblique washers in accordance with GOST 5157 is made of steel grades 20 and 35.

1.1.1. The mass fraction of sulfur in steel should be no more than 0.040%, phosphorus - no more than 0.035%. For steel grades 11kp and 18kp used for cladding, the mass fraction of sulfur should be

no more than 0.035%, phosphorus - no more than 0.030%.

1.1.2. The residual mass fraction of nickel in steel of all grades should not exceed 0.30%, mediv of steel grades 11kp and 18kp - 0.20%, in steel of other grades - 0.30%.

1.1.3. In steel grades 35, 40, 45, 50, 55 and 60, intended for the manufacture of patented wire, the mass fraction of manganese should be 0.30-0.60%, nickel - no more than 0.15%, chromium - no more than 0.15 %, copper - no more than 0.20%. The mass fraction of sulfur and phosphorus is in accordance with the requirements of the wire standards, but does not exceed the standards given in clause 1.1L.

1.1.4. In steel grades 08ps, 10ps, 15ps and 20ps, intended for the production of rolled sheets for cold stamping, a mass fraction of manganese up to 0.25% is allowed according to the lower limit.

1.1.5. In steel grades 08ps, 10ps, 15ps and 20ps, a mass fraction of silicon less than 0.05% is allowed, provided that deoxidizers other than silicon are used in the required quantities.

1.1.6. In steel, the mass fraction of arsenic is allowed to be no more than 0.08%.

1.1.7. The mass fraction of nitrogen in oxygen-converter steel should not exceed 0.006% for rolled sheets and strip and 0.008% for other types of rolled products.

1.1.8. According to the order in quiet steel, produced by scrap process and scrap

ore process, a residual mass fraction of nickel and chromium of no more than 0.40% each is allowed.

1.2. In rolled products, billets, forgings and further processing products, deviations in chemical composition from the standards given in Table 1 are allowed in accordance with Table 2.

1.3. The range of rolled products must meet the requirements:

GOST 2590 - for hot-rolled rounds;

GOST 2591 or other regulatory and technical documentation - for hot-rolled square;

GOST 1133 - for forged round and square;

GOST 2879 - for hot-rolled hexagonal;

GOST 103 - for hot-rolled strip;

GOST 4405 - for forged strip;

GOST 5157 - for profiles for oblique washers;

GOST 7417 - for calibrated round;

GOST 8559 - for calibrated square;

GOST 8560 - for calibrated hexagonal;

normative and technical documentation - for calibrated strip;

GOST 14955 - with special surface finishing.

Examples of symbols are given in Appendix 1.

(Changed edition, Amendment No. 1).

table 2

2. TECHNICAL REQUIREMENTS

2.1. Characteristics of the basic version

2.1.1. Rolled products of unmeasured length (ND) with maximum deviations for normal dimensional accuracy, curvature, ovality and other requirements for shape, crescent shape and deviation from flatness, class 2 according to GOST 103 (for strip).

2.1.2. Rolled products of calibrated unmeasured length (ND) with maximum deviations for field tolerance - h11, ovality - no more than maximum deviations in diameter.

2.1.3. Rolled products with special surface finishing of unmeasured length (ND) with maximum deviations for the tolerance field - h11, ovality - no more than half of the maximum deviations for diameter.

2.1.4. Long-rolled products without heat treatment, calibrated and with a special surface finish, hard-worked - NG or heat-treated (annealed, highly tempered, normalized, normalized with tempering, hardened with tempering) - TO.

2.1.5. Long rolled products of two surface quality groups: 2GP and 3GP. Rolled products of surface quality group 2РП are intended mainly for hot forming, group 3ГП - mainly for cold machining.

2.1.6. On the surface of rolled products of surface quality group 2GP there should be no rolled bubbles, rolling films, sunsets, cracks, contamination, or stress cracks.

2.1.1—2.1.6. (Changed edition, Amendment No. 1).

2.1.6.1. Defects on the surface must be removed by flat cutting or grinding, the width of which must be at least five times the depth.

The depth of cleaning defects, based on the actual size, should not exceed:

half the size tolerance - for rolled products with a size of less than 80 mm;

size tolerance - for rolled products with sizes from 80 to 140 mm;

5% of diameter or thickness - for rolled products with sizes from 140 to 200 mm;

6% of diameter or thickness - for rolled products larger than 200 mm.

In one section of rolled products with a size (diameter or thickness) of more than 140 mm, no more than two strippings of maximum depth are allowed.

2.1.6.2. On the rolled surface, individual risks, dents and ripples with a depth within half the size tolerance, as well as rolled out bubbles and dirt (hairs) with a depth not exceeding the size tolerance, but not more than 0.20 mm, based on the actual size, are allowed without cleaning.

2.1.7. On the surface of rolled products with surface quality of group 3GP, local defects with a depth not exceeding the minus maximum deviation per size for rolled products with a size of less than 100 mm are allowed; size tolerance - for rolled products with a size of 100 mm or more.

The depth of defects is calculated from the nominal size.

(Changed edition, Amendment No. 1).

2.1.8. Rolled products must be cut.

Crumpled ends and burrs are acceptable.

The bevel of cutting long products up to 30 mm in size is not regulated; over 30 mm, it should not exceed 0.1 of the diameter or thickness. Rolled sections up to 40 mm in size of unmeasured length may be produced with uncut ends.

2.1.9. The surface quality and requirements for cutting the ends of calibrated rolled products must comply with GOST 1051 groups B and C, with special surface finishing - GOST 14955 groups B, D and D.

In rolled products with special surface finishing, decarburization is not allowed.

2.1.10. The hardness (TB1) of long products without heat treatment should not exceed 255 HB, calibrated and with a special surface finish of cold-worked steel - 269 HB.

(Changed edition, Amendment No. 1).

2.1.11. The mechanical properties of rolled products in a normalized state (M1) must comply with the standards given in Table 3.

Table 3

Notes:

The standards of mechanical properties given in Table 3 apply to rolled products with a diameter or thickness of up to 80 mm. For rolled products with a diameter or thickness over 80 mm, a reduction in relative elongation by 2% (abs.) and relative contraction by 5% (abs.) is allowed.
Standards of mechanical properties for workpieces forged from bars with a diameter or thickness of over 120 to 250 mm for rolled products with a diameter or thickness of 90 to 100 mm must correspond to those given in Table 3.
By agreement between the manufacturer and the consumer, for steel grades 25–60, it is allowed to reduce the tensile strength by 20 N/mm 2 (2 kgf/mm 2) compared to the standards specified in Table 3, while simultaneously increasing the elongation standards by 2% (abs. .).

(Changed edition, Amendment No. 1).

2.1.12. The macrostructure of rolled products should not have shrinkage cavities, looseness, bubbles, delaminations, internal cracks, slag inclusions and flakes.

2.2. Customer specifications

2.2.1. Rolled steel grades 20, 25, 30, 35, 40, 45, 50 with a mass fraction of boron of 0.002-0.006%.

In this case, the letter P is placed at the end of the brand designation.

2.2.2. Rolled steel from mild steel with a mass fraction of silicon of 0.17-0.27%.

2.2.3. Rolled cut lengths (MD).

2.2.4. Rolled lengths that are a multiple of the measured length (KD).

2.2.5. Rolled products calibrated and with a special surface finish with a tolerance range of h12.

2.2.6. Long products in a heat-treated state (annealed, highly tempered, normalized, normalized with tempering) - TO.

2.2.7. Rolled products with surface quality of group 1GP - without rolled bubbles and contaminants (hairs) and tested for hot upsetting (65).

Rolled products are intended primarily for hot upsetting, heading and stamping. The manufacturer may not test rolled products over 80 mm in size.

2.2.8. Rolled steel grades 25, 30, 35, 40, 45, 50 with impact strength control (ICH) at

heat-treated (quenching + tempering) samples.

Impact strength standards must correspond to those indicated in Table 4.

2.2.9. Rolled products calibrated in a cold-worked or heat-treated state with standardized mechanical properties (M2) in accordance with the requirements specified in table. 5.

Table 4

Table 5

2.2.10. Rolled products with a microstructure (MCS) normalized in points in accordance with the requirements specified in table. 6.

Table 6

Note. For rolled products with a size of 70 mm or more with a surface quality of group B, subcortical bubbles of point 2 are allowed to a depth of no more than 1/2 of the tolerance for diameter or thickness.

2.2.11. Rolled products with standardized hardness (TB2) in accordance with the requirements given in table. 7.

Table 7

2.2.12. Rolled products with ultrasonic testing (UT) of internal defects in accordance with GOST 21120.

2.2.13. Rolled products ensuring weldability (WS).

2.2.14. Rolled steel grades 35, 40, 45, 50, 55, 58 (55pp), 60, intended for surface hardening with high frequency currents, with decarburization (ferrite + transition zone) no more than 1.5% of the diameter or thickness per side (1C ).

2.2.3—2.2.14. (Changed edition, Amendment No. 1).

2.2.15. (Deleted, Amendment No. 1).

2.3. Characteristics established by agreement between the consumer and the manufacturer

2.3.1. Rolled products with reduced carbon mass fraction limits compared to those given in Table 1, but not less than 0.05%.

2.3.2. Rolled products with reduced carbon mass fraction limits compared to those given in Table 1, but not less than 0.05%, without taking into account the permissible deviations in finished rolled products specified in Table 2.

2.3.3. Rolled products with a mass fraction of sulfur of 0.020–0.040%.

2.3.4. Rolled products with a mass fraction of sulfur not exceeding 0.025%.

2.3.5. Rolled products with a phosphorus mass fraction of no more than 0.030%.

2.3.6. Rolled products with a mass fraction of copper not exceeding 0.25%.

2.3.7. Long products with a diameter or thickness of over 30 to 140 mm with removal of burrs (UZ) and crumpled ends.

2.3.8. For rolled steel with increased hardness by 15 HB compared to those given in Table 7 (TB3).

2.3.9. Rolled products with standardized mechanical properties (M3), determined on samples cut from heat-treated blanks (hardening + tempering) of the size specified in the order, in accordance with the requirements of Table. 8.

Table 8

Notes

Standards of mechanical properties before 01/01/92 are not rejected; determination is required.
The mechanical properties of steel 30 apply to rolled products up to 63 mm in size.
The values of mechanical properties are given for rolled products with a round section. For rectangular sections, ranges of equivalent diameters are given in Appendix 2.2.3.10. Rolled products with normalized hardenability (HR) in accordance with Appendices 3 and 4.

2.3.11. Rolled steel grades 35, 40, 45, 50, 55, 58 (55pp), 60, intended for surface hardening with high frequency currents, with decarburization (ferrite + transition zone) no more than 0.5% of the diameter or thickness per side (2C ).

2.3.12. Rolled products in pickled condition (T).

2.3.6—2.3.12. (Changed edition, Amendment No. 1).

2.3.13. Rolled products calibrated with tolerance range h10.

2.3.14. Hot-rolled bars with increased (B) and high (A) dimensional accuracy.

2.3.15. Rolled products with surface quality group 2GP with hot upsetting test (65).

The manufacturer may not test rolled products over 80 mm in size.

2.3.16. Rolled steel grades 45, 50, 50A with hardness control (TV4) on hardened samples in accordance with the requirements specified in Table 8a.

2.3.17. The mass fraction of nitrogen is not more than 0.008% in oxygen-converter steel for thin sheets.

2.3.13—2.3.17. (Introduced additionally, Amendment No. 1).

2.4. It is allowed in the technical specifications for specific products to provide for additional or increased characteristics not provided for by this standard.

A list of additional characteristics is given in Appendix 5.

2.5. Marking and packaging of rolled products - in accordance with GOST 7566.

2.5.1. Packaging of calibrated rolled products is in accordance with GOST 1051, with special surface finishing - in accordance with GOST 14955.

2.5.2. The marking is applied directly to the product if the product is not subject to packaging, and on the label if the product is packaged in bundles, skeins and coils.

Table 8a

3. ACCEPTANCE RULES

3.1. Rolled products are accepted in batches consisting of steel of one heat, one size and one heat treatment mode (when manufactured in a heat-treated state).

By agreement between the manufacturer and the consumer, batches are formed from steel of the same grade of several heats of the same size.

Each batch is accompanied by a quality document in accordance with GOST 7566.

When deoxidizing agents other than silicon are used for semi-quenched steel, a corresponding indication is made in the quality document.

For rentals accepted with characteristics established by the consumer in accordance with paragraphs. 2.2 and 2.3, the quality document indicates the test results for the ordered indicators.

3.2. The rolled products are subjected to acceptance tests.

3.3. To check the quality, the following are selected from a batch of rolled products:

for chemical analysis - samples in accordance with GOST 7565. The manufacturer periodically controls residual copper, nickel, chromium, arsenic and nitrogen, at least once a quarter. When producing steel, taking into account the manganese equivalent, control of residual copper, nickel and chromium is carried out at each heat;
to control surface quality and dimensions - all rods, strips and coils;
to control the macrostructure by fracture or etching, to test for impact bending, to determine the depth of the decarbonized layer - two rods, strips or coils;
to test hardness - 2% of rods, strips or coils, but not less than 3 pieces;
for tensile testing - one rod, strip or coil for control in a normalized state, two rods, two strips or two coils for control in a cold-worked, annealed, high-tempered or tempered condition;
to determine hardenability - one rod, strip or coil from a ladle melt of steel of all grades that do not contain boron, and two rods, two strips or two coils from a ladle melt of steel grades containing boron;
to determine the grain size - one rod, strip or coil from a melting ladle;
for slump testing - three rods, strips or coils;
To determine hardness after hardening, use two longitudinal samples from the melt.

(Changed edition, Amendment No. 1).

3.4. If unsatisfactory test results are obtained for at least one of the indicators, repeated tests are carried out in accordance with GOST 7566.

The results of repeated tests are applied to the entire batch.

4. TEST METHODS

4.1. Chemical analysis of steel is carried out according to GOST 22536.0—GOST 22536.9, GOST 27809, GOST 12359 or other methods that are not inferior in accuracy to standard ones. If disagreements arise, chemical analysis is carried out according to GOST 22536.0—GOST 22536.9, GOST 27809, GOST 12359.

4.2. The quality of the surface is checked by inspection of the rolled product without the use of magnifying devices. If necessary, the surface is brightened or etched, and for rolled products with a special surface finish with a diameter of up to 3 mm inclusive, the inspection is carried out at a magnification of up to 10 x. The depth of defects on the surface of the rolled product is determined by control cleaning or filing with a file.

4.3. Geometric dimensions and shape are determined using measuring instruments in accordance with GOST 26877, GOST 162, GOST 166, GOST 427, GOST 2216, GOST 3749, GOST 5378, GOST 6507, GOST 7502, or tools certified in accordance with GOST 8.001* or GOST 8.326*.

4.4. Sampling from coils for all types of tests is carried out at a distance of at least 1.5 turns from the end of the roll.

4.5. From each rod, strip or coil selected for inspection, the following is taken:

for tensile and upset testing, to determine the grain size, hardenability and depth of the decarbonized layer - from one sample;
for impact bending testing - one sample of each type;
to control the macrostructure - one template.

4.6. Sampling for slump testing is in accordance with GOST 7564.

4.7. Sampling for testing mechanical properties according to tables 3 and 5 is carried out according to GOST 7564 (option 1), according to tables 4 and 8 - according to GOST 7564 (option 2).

(Changed edition, Amendment No. 1).

4.7a. Selection of samples to determine hardness after hardening is carried out according to the scheme given in Appendix 8.

Samples for control can be cut from finished rolled products or final billets (in heat control).

(Introduced additionally, Amendment No. 1).

The samples are heated to a forging temperature of 850–1000°C and upset by 65% relative to the original height. There should be no open cracks or sunsets on the deposited samples.

(Changed edition, Amendment No. 1).

4.9. Brinell hardness is determined according to GOST 9012. The hardness of rolled products with a diameter or thickness of less than 5 mm is not determined.

4.9a. Rockwell hardness after quenching is determined according to GOST 9013 on a site located in the middle of the length of the sample. The surface of the site for hardness measurement is subjected to cleaning: in this case, the surface roughness Ra should be no more than 1.25 microns according to GOST 2789.

(Introduced additionally, Amendment No. 1).

4.10. The tensile test is carried out according to GOST 1497 on samples of five times the length with a diameter of 5 or 10 mm.

For rolled products with a diameter or thickness up to 25 mm inclusive, testing may be carried out on samples without mechanical treatment.

The impact strength test is carried out according to GOST 9454 on type 1 samples.

The direction of the sample axis is along the rolling direction.

4.11. Samples for tensile testing of rolled products in accordance with the requirements of Table 3 are cut from normalized blanks with a diameter or square side of 25 mm.

PR 50.2.009-94 is in force on the territory of the Russian Federation.

For rods with a diameter of less than 25 mm, normalization is carried out in the finished section of the rod (without cutting the workpiece).

Note. For rods larger than 120 mm, sampling for mechanical tests can be carried out from forged or re-rolled blanks with a cross-section of 90-100 mm.

4.12. Samples for tensile testing of rolled products in accordance with the requirements of Table 8 are cut from heat-treated blanks of the size specified by the consumer.

4.13. The heat treatment modes of workpieces (specimens) for testing mechanical properties are given in Appendices 6 and 7, for hardness control after hardening - in Appendix 9.

(Changed edition, Amendment No. 1).

4.14. Inspection of the macrostructure for fractures or etched templates is carried out without the use of magnifying devices in accordance with GOST 10243.

It is allowed to use ultrasonic testing (UT) and other non-destructive testing methods, agreed upon in the prescribed manner.

4.15. The depth of the decarbonized layer is determined according to GOST 1763.

4.16. Hardenability is determined by the method of end hardening according to GOST 5657.

4.17. The grain size is determined according to GOST 5639.

4.18. On steel of one heat that has passed tests for macrostructure, hardenability and mechanical properties on large rolled sections, the manufacturer may not carry out the above tests when producing smaller rolled sections.

4.19. The manufacturer is allowed to use statistical and non-destructive testing methods according to a methodology agreed upon in the prescribed manner. In case of disagreement and during periodic checks of product quality, the control methods provided for in this standard are applied.

5. TRANSPORTATION AND STORAGE

5.1. Transportation and storage - in accordance with GOST 7566 with the following addition.

5.1.1. Products are transported by all types of transport in accordance with the rules for the transportation of goods in force for this type of transport. By rail, transportation is carried out depending on the weight and overall dimensions in covered or open cars. The weight of the cargo package should not exceed 10,000 kg for mechanized loading in open vehicles, and 1,250 kg in covered vehicles. Packaging, means and methods for forming packages - in accordance with GOST 7566.

When sending two or more packages, the dimensions of which make it possible to arrange a transport package with overall dimensions in accordance with GOST 24597, the packages must be formed into transport packages. Fastening means - according to GOST 21650.

(Changed edition, Amendment No. 1).

ANNEX 1

Mandatory

EXAMPLES OF RENTAL SYMBOLS

SCHEME 1 RENTAL SYMBOL

In the design documentation it is allowed to provide examples of symbols in accordance with Scheme 2.

Examples of symbols

Long-rolled products, round, normal rolling hardness (B), curvature class II, unmeasured length (ND), diameter 100 mm according to GOST 2590-88, made of grade 30 steel, surface quality group 2GP, with mechanical properties according to Table 3 (M1), with hardness according to clause 2.1.10 (TV1), with impact strength control according to Table 4 (KUV), with deburring (US), with hot upset test (65), without heat treatment:

Circle V-11-ND-100 GOST 2590-88/30-2GP-M1-TV1-KUV-UZ-66 GOST 1050-88

Long-rolled products, square, with increased rolling precision (B), class I in curvature, cut length (MD), with a square side of 25 mm in accordance with GOST 2591-88, from steel grade 35, with surface quality of group 1GP, with mechanical properties according to the table .8 (M3), with hardness according to table 7 (TB2), with macrostructure (KMS) normalized in points according to table 6, with decarburization according to clause 2.2.14 (1C), heat treated (HT):

Square B-1-MD-25 GOST 2591-88/35-1GP-M3-TV2-KMS-1S-TO GOST 1050-88

Rolled strip, normal rolling accuracy (B), sickle shape class 2, deviation from flatness class 2, multiple measured length (CD), thickness 36 mm, width 90 mm according to GOST 103-76, from steel grade 45, with surface quality group 3GP , with mechanical properties according to Table 3 (M1), with hardness item 2.1.10 (TV1), with normalized hardenability (HR), without heat treatment:

Strip V-2-2-KD-36x90 GOST 103-76/45-3GP-M1-TV1-PR GOST 1050-88

Hot-rolled profile for oblique washers, cut-to-length (MD), with dimensions 2ВхНхй = 32x5.8x4 mm according to GOST 5157-83, made of grade 35 steel, with surface quality group 3GP, with mechanical properties according to Table 3 (M1), with hardness according to clause 2.1.10 (TV1), without heat treatment:

Profile for oblique washers MD-32x5.8x4 GOST5157-83/35-3GP-M1-TV1

Calibrated rolled products, round, with a tolerance range according to L11, cut length (MD), with a diameter of 10 mm according to GOST 7417-75, made of grade 45 steel, with surface quality of group B according to GOST 1051-73, with mechanical properties according to Table 5 ( M2), with hardness according to clause 2.3.8 (TV3), with decarburization according to clause 2.3.11 (2C), cold-worked (NG):

Circle M1-MD-10 GOST 7417-75/45-V-M2-TV3-2S-NGGOST 1050-88

Calibrated, square rolled products, with a tolerance range of L1, a multiple of the measured length (CD), with a square side of 15 mm in accordance with GOST 8559-75, from steel grade 20, with surface quality of group B in accordance with GOST 1051-73, with mechanical properties according to Table 8 (M3), with hardness according to table. 7 (TV2), ensuring weldability (GS), cold-worked (NG):

Square M1-KD-15 GOST 8559-75/20-B-M3-TV2-GS-NGGOST 1050-88

Calibrated rolled products, hexagonal, with a tolerance range of h12, of unmeasured length (ND), with an inscribed circle diameter of 8 mm according to GOST 8560-78, made of grade 45 steel, with surface quality of group B according to GOST 1051-73, with mechanical properties according to Table 3 (M1), with hardness according to table. 8a (TV4), heat treated (TO):

Hexagon M2-ND-8 GOST 8560-78/45-V-M1-TV4-TO GOST 1050-88

Rolled products with special surface finishing, round, with tolerance range L11, of unmeasured length (ND), with a diameter of 8 mm, with surface quality of group B according to GOST 14955-77, made of grade 20 steel, with mechanical properties according to Table 5 (M2), with hardness according to table 7 (TV3) cold-worked (NG):

Circle M1-ND-8 GOST 14955- 77/20-V-M2-TV3-NG GOST 1050- 88

Examples of symbols that can be given in design documentation:

Rolled products with special surface finishing, round, with tolerance range L11, unmeasured length (ND), diameter 8 mm, surface quality group B according to GOST 14955-77, made of grade 20 steel, with mechanical properties according to Table 5 (M2), with hardness according to table 7 (TV3), cold-worked (NG):

(Changed edition, Amendment No. 1).

APPENDIX 2 Mandatory

CONVERSION OF RECTANGULAR SECTIONS INTO ROUND WITH THE SAME MECHANICAL PROPERTIES

Damn.1

APPENDIX 3 Mandatory

HARDENABILITY STRIPS OF STRUCTURAL CARBON STEEL

Steel grade 35

Damn.2

Steel grade 40

Damn.3

Steel grade 45

Damn.4

APPENDIX 4 Mandatory

PARAMETERS OF BRAND STRIPS (LIMITS OF FLUCTUATIONS IN HARDNESS HRC (HRC 3) AND HRB ACCORDING THE LENGTH OF THE END SAMPLE)

Table 9

RENTAL CHARACTERISTICS INSTALLED BY AGREEMENT OF THE CONSUMER WITH THE MANUFACTURER IN THE NTD

1. Rolled products with a normalized mass fraction of nitrogen in electric steel.

2. Rolled products with a lower hourly fraction of manganese, reduced against the norms of the table. 1 per manganese equivalent equal to:

B M = 0.3(Cr%)+0.5 (Ni%) + 0.7 (Ci%),

where Cr, Ni, Cu is the residual actual mass fraction of chromium, nickel, copper in steel, not exceeding the standards specified in Table 1.

3. Rolled products calibrated from steel grades 08, 55 and 60 in a cold-worked or heat-treated state with control of mechanical properties.

4. Rolled products with normalized impact strength on type I samples at a temperature of minus 40°C.

5. Rolled products with normalized impact strength on type II samples at temperatures of plus 20°C and sub-zero temperatures.

6. Rolled without control of relative contraction.

7. Rolled products calibrated and with a special surface finish with normalized hardness, normalized with tempering and hardened with tempering.

8. Long-rolled products with standardized hardness in a normalized state.

9. Rolled products with standardized hardness within specified limits.

10. Rolled products without hardness control.

11. Rolled products with a standardized austenite grain size.

12. Rolled products with standardized purity for non-metallic inclusions.

13. Rolled products with standardized purity based on hair fibers identified on the surface of finished parts using the magnetic method or etching.

14. Rental of small-tonnage lots.

Heat treatment modes for workpieces to control the mechanical properties given in Tables 3 and 4

Table 10

when normalizing or hardening - 30 minutes; when tempering 200°C - 2 hours;
when tempering 600°C - 1 hour.
The cooling medium during quenching is water.

Heat treatment modes for workpieces to control the mechanical properties given in Table 8

Table 11

APPENDIX 8 Mandatory

SAMPLE SELECTION SCHEME FOR DETERMINING HARDNESS AFTER HARDENING

Modes of thermal treatment of samples to determine hardness after hardening, given in table. 8a

Table 12

Notes:

Holding time during hardening (after reaching the hardening temperature) 20 min.
Oil temperature (65±10)°C.

APPENDICES 8, 9 (Introduced additionally, Amendment No. 1).

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the USSR Ministry of Ferrous Metallurgy

2. APPROVED AND ENTERED INTO EFFECT by Resolution of the USSR State Committee on Standards dated November 24, 1988 No. 3811

3. INSTEAD GOST 1050-74

4. REFERENCE REGULATIVE AND TECHNICAL DOCUMENTS

5. The validity period was lifted according to Protocol No. 5-94 of the Interstate Council for Standardization, Metrology and Certification (IUS 11-12-94)

6. REISSUE (April 1996) with Change No. 1, approved in December 1991 (IUS 4-92)

Substitutes for steel 20 are steel 15 and steel 25.

Designation of steels according to GOST 1050-88

When designating steel 20:

the word "steel" is written in full,
the number 20 is written separately (separated by a space),
there is no point.

For example, “steel 20” or exactly according to the standard “steel grade 20”. This is the difference between the designations of structural carbon quality steels and those according to GOST 380-2005. The number after the word “steel” indicates the nominal carbon content of the steel in hundredths of a percent. For steel 20, this is 0.20% carbon.

Unlike high-quality steels (steel 20, steel 25 and others), ordinary steels according to GOST 380-2005 are designated abbreviated, continuous and without a dot, for example, st3 or st4. If we really follow the letter of the standard, then “steel grade St3”.

Steel 20: chemical composition

The chemical composition of steel 20 is determined by GOST 1050-88:

carbon: 0.17-0.24%;
silicon: 0.17-0.37%;
manganese: 0.35-0.65%;
copper: no more than 0.25%;
nickel: no more than 0.25%;
arsenic: no more than 0.08%;
sulfur: no more than 0.4%;
phosphorus: no more than 0.035%.

Steel structure 20

Typical structure of steel 20 – . 20 it is possible to obtain a lath martensite structure. Thermally strengthened rolled steel 20 is used for the manufacture of hardware products (strength class 8.8).

Technological properties of steel 20

forging start temperature - 1280° C,
forging completion temperature - 750° C,
Forging cooling is air.

Not prone to flake formation.

Not prone to temper brittleness.

Weldability of steel 20:

no limits;
without preheating;
without subsequent heat treatment.

Application of steel 20

The following are made from steel 20:

lightly loaded parts (pins, axles, copiers, stops, gears);
cemented parts for long-term operation, including at temperatures up to 350° C;
crane hooks;
bearing shells and other parts for operation under pressure at temperatures from minus 40 to 450 °C.

Steel 20 after chemical-thermal treatment is used for parts with high surface strength (worms, worm pairs, gears). Steel 20 is widely used for the production of pipeline fittings, steam pipelines, seamless high-pressure pipes, welded rectangular and square profiles.

Types of steel supply 20

Types of steel supply 20:

long products;
calibrated rod;
ground rod;
silverfish;
thick sheet;
thin sheet thin;
ribbon;
band;
wire;
forgings and forged blanks;
pipes.