This standard applies to hot-rolled steel bars. Class A3 reinforcement has a periodic profile, i.e. round profile with 2 longitudinal ribs and transverse ledges. For this class, certain steel grades are established (GOST 5781-82) - 35GS, 25G2S.

Fittings class A3 GOST 5781-82
Profile number	Weight of 1 m profile, kg	Area cross section, cm 2
6	0,222	0,283
8	0,395	0,503
10	0,617	0,785
12	0,888	1,131
14	1,210	1,540
16	1,580	2,010
18	2,000	2,540
20	2,470	3,140
22	2,980	3,800
25	3,850	4,910
28	4,830	6,160
32	6,310	8,040
36	7,990	10,180
A400S and A500S class fittings - thermomechanically hardened reinforcing steel (TU 14-1-5254-94). This reinforcing steel meets the requirements international standards. Gosstroy of Russia recommends the use of A400C and A500C reinforcing steel in reinforced concrete structures along with and instead of A3 and A-3C reinforcing steel of the same diameters.

Rebar (STO ASCHM 7-93)

Periodic profile bars intended for reinforcing ordinary reinforced concrete structures, as well as non-stressed reinforcement bars of prestressed reinforced concrete structures, are produced according to STO ASChM 7-93.

Depending on the mechanical properties reinforcement is divided into strength classes:

A400C;
- A500S;
- A600S.

STO ASChM 7-93 applies to rods:

Mechanically hardened in a cold state;
- thermomechanically hardened in the rolling flow;
- hot-rolled without further processing.

Nominal diameter, dn (profile number)	Cross-sectional area of ​​the rod, mm2	Theoretical weight 1 m, kg
6	28,3	0,222
8	50,3	0,395
10	78,3	0,617
12	113	0,888
14	154	1,21
16	201	1,58
18	254	2
20	314	2,47
22	380	2,98
25	491	3,85
28	616	4,83
32	804	6,31
36	1018	7,99
40	1257	9,87

3.1. Reinforcing steel is accepted in batches consisting of profiles of the same diameter, one class of one melting ladle and issued with one quality document.
The mass of the batch must be up to 70 tons.
It is allowed to increase the mass of the batch up to the mass of the melting ladle.
3. 2. Each batch is accompanied by a quality document in accordance with GOST 7566-81 with additional data:
profile number;
Class;
the minimum mean X and the standard deviations S 0 in a batch of σ T (σ 0.2) and σ B ;
cold bend test results;
values ​​of uniform elongation for steel class A - IV (A600), A-V (800), A-VI (A1000).
3.3. To check the dimensions and surface quality, select:
in the manufacture of reinforcing steel in rods - at least 5% of the batch;
when manufactured in skeins - two skeins from each batch.

3 4. To check chemical composition samples are taken according to GOST 7565-81.
Mass fraction aluminum manufacturer determines periodically, but at least once a quarter.
3.5. To test for tension, bending and impact strength, two rods are selected from the batch
For the manufacturer, the interval for the selection of rods must be at least half the time spent on rolling one profile size of one batch

3 6 Upon receipt of unsatisfactory test results for at least one of the indicators, repeated tests are carried out in accordance with GOST 7566-81.

4. Test methods

4.1. Chemical analysis steels are carried out according to GOST 12344-88, GOST 12348-78, GOST 12350-78, GOST 12352-81, GOST 12355-78, GOST 12356-81, GOST 18895-81 or other methods that provide the required accuracy.
4.2. The diameter and ovality of the profiles are measured at a distance of at least 150 mm from the end of the rod or at a distance of at least 1500 mm from the end of the coil with a coil mass of up to 250 kg and at least 3000 mm with a coil mass of more than 250 kg.
4.3. Dimensions are checked with a measuring tool of the required accuracy.
4.4. One sample is cut from each selected rod for tensile, bending and impact testing.
4.5. Sampling for tensile testing, bending and impact strength is carried out according to GOST 7564-73.
4.6. The tensile test is carried out according to GOST 12004-81.
4.7. The bending test is carried out according to GOST 14019-80 on samples with a cross section equal to the cross section of the rod.
For rods with a diameter of more than 40 mm, it is allowed to test samples cut along the axis of the rod, on a mandrel, with a diameter reduced by half compared to that indicated in Table. 4 with a bending force applied from the side of the cut.
4.8. Determination of impact strength is carried out according to GOST 9454-78 on samples with a concentrator type U type 3 for rods with a diameter of 12-14 mm and type 1 samples for rods with a diameter of 16 mm or more. Samples are made in accordance with the requirements of GOST 9454-78.
4.9. It is allowed to use statistical and non-destructive methods to control the mechanical properties and mass of profiles.
4.10. The curvature of the rods is measured on the length of the supplied profile, but not shorter than 1 m.
4.11. Determination of statistical indicators of mechanical properties in accordance with the mandatory Appendix 2.
4.12. The quality of the surface is checked without the use of magnifying instruments.

4.13. The measurement of the height of the transverse protrusions of a periodic profile should be carried out along the vertical axis of the cross section of the reinforcing bar.

5. Packing, marking, transportation and storage

5.1. Packing, marking, transportation and storage - in accordance with GOST 7566-81 with additions:
the ends of the rods made of low-alloy steels of class A-IV (A600) must be painted with red paint, class A-V- red and green, class A-VI (A1000) - red and blue. It is allowed to color the bundles at a distance of 0.5 m from the ends;
the rods are packed in bundles weighing up to 15 tons, tied with wire or rolled wire. At the request of the consumer, the rods are packed in bundles weighing up to 3 and 5 tons.
On ligaments, the paint is applied in stripes with a width of at least 20 mm on the side surface along the circumference (at least 1/2 of the circumference) at a distance of not more than 500 mm from the end.
The paint is applied to the coils in strips with a width of at least 20 mm across the coils from the outside of the coil.
On unpackaged products, paint is applied to the end or to the side surface at a distance of not more than 500 mm from the end.
On the label attached to each bundle of rods, the accepted designation of the class of reinforcing steel (for example, A-III) is applied or symbol yield strength class (A400).

GOST 5781-82

Developed by the State
Committee of the Russian Federation for Standardization
and metrology

HOT-ROLLED STEEL FOR REINFORCED CONCRETE STRUCTURES REINFORCEMENT

Specifications

This standard applies to hot-rolled round steel of a smooth and periodic profile, intended for the reinforcement of conventional and prestressed reinforced concrete structures (reinforcing steel).
In terms of the norms for the chemical composition of low-alloy steels, the standard also applies to ingots, blooms and billets.
(Revised edition, Rev. No. 4).

1. CLASSIFICATION AND ASSORTMENT

1.1. Depending on the mechanical properties, reinforcing steel is divided into classes A-I (A240), A-I (AZOO), A-III (A400); A-IV (A600), A-V (A800), A-VI (A1000).
1.2. Reinforcing steel is produced in rods or coils. Reinforcing steel of class A-I (A240) is made smooth, classes A-II (A300), A-III (A400), A-IV (A600); A-V (A800) and A-VI (A1000) - periodic profile.
At the request of the consumer, steel of classes A-II (A300), A-III - (A400), A-IV (A300) l A-V (A800) is made smooth,
1.1; 1.2. (Revised edition, Rev. No. 5).
1.3. Profile numbers, cross-sectional areas, weight of 1 m of length of reinforcing steel of a smooth and periodic profile, as well as maximum mass deviations for periodic profiles must correspond to those indicated in Table. one.
1.4. The nominal diameters of periodic profiles must correspond to the nominal diameters of smooth profiles of equal cross section.

Table 1

Profile number	Cross-sectional area, cm 2	Weight 1 m profile
		Theoretical, kg	Limit deviations, %
6 8	0,283 0,503	0,222 0,395	+9,0; -7,0
10 12 14	0,785 1,131 1,540	0,617 0,888 1,210	+ 5,0; - 6,0
16 18 20 22 25 28	2,010 2,540 3,140 3,800 4,910 6,160	1,580 2,000 2,470 2,980 3,850 4,830	+ 3,0; -5,0
32 36 40 45	8,040 10,180 12,570 15,000	6,310 7,990 9,870 12,480	+ 3,0; -4,0
50 55 60 70 80	19,630 23,760 28,270 38,480 50,270	15,410 18,650 22,190 30,210 39,460	+2,0; -4,0

(Changed edition, Rev. No. 3)
1.5. The mass of 1 m of the profile is calculated from nominal dimensions with a steel density of 7.85 g/cm 3 . The probability of providing a mass of 1 m must be at least 0.9.

1.6. Limit deviations of the diameter of smooth profiles must comply with GOST 2590-88 for normal rolling accuracy.
1.7. Reinforcing steel of a periodic profile is a round profile with two longitudinal ribs and transverse ledges running along a three-start helix. For profiles with a diameter of 6 mm, protrusions running along a single-start helix are allowed, with a diameter of 8 mm - along a two-start helix.
1.8. Reinforcing steel of class A-II (A300), made in the usual version, with a profile shown in the devil. 1a and special purpose Ac-II (Ac300) profile shown in Fig. 2a, should have protrusions running along helical lines with the same lead on both sides of the profile.
Steel class A-III (A400), manufactured by the profile shown in Fig. 1b, and classes A-I V (A600), A-V (A800), A-VI (A 1000) profile shown in Fig. 1b, 2b, should have protrusions along helical lines, having right-handed on one side of the profile, and left-handed entries on the other.
Reinforcing steel for special purposes of class Ac-II (Ac300) is made with profiles shown in Fig. 1a or 2a.
The profile shown in hell. 2a, special purpose is manufactured by agreement between the manufacturer and the consumer. The shape and dimensions of the profiles shown in Fig. 2a and b can be specified.
1.9. The dimensions and maximum deviations of the dimensions of the reinforcing steel of a periodic profile, manufactured according to drawings 1a and b, must correspond to those given in table. 2, but damn. 2 a and b - given in table. 3.
1.10. Relative displacements of helical protrusions along the sides of the profile, separated by longitudinal ribs, are not standardized.
Dimensions for which limit deviations are not set are given for building a gauge and are not checked on the finished profile.
1.11. The ovality of smooth profiles (the difference between the largest and smallest diameters in one section) should not exceed the sum of the plus and minus limit deviations in diameter.
1.9.-1.11. (Revised edition, Rev. No. 3).
1.12. Reinforcing steel of classes A-I (A240) and A-II (A300) with a diameter of up to 12 mm and class A-III (A400) with a diameter of up to 10 mm inclusive, is made in coils or rods, large diameters - in rods. Reinforcing steel of classes A-IV (A600), A-V (A800) and A-VI (AYUOO) of all sizes are made in rods, with a diameter of 6 and 8 mm, they are produced, by agreement between the manufacturer and the consumer, in coils.
1.13. Rods are made from 6 to 12 m long:
- measured length;
- measured length with unmeasured segments - not less than 2 m long, not more than 15% of the batch weight;
- unmeasured length.
In a batch of rods of random length, rods with a length of 3 to 6 m are allowed, not more than 7% of the mass of the batch.

Profile number (nominal diameter dn)	d		h		d1	h1	t	b	b1	r
	Rated	Previous off	Rated	Previous off
6 8 10 12 14 16 18 20 28 32 36 40 45 50 70 80	5,75 7,5 9,3 11,0 13,0 15,0 17,0 19,0 21,0 24,0 26,5 30,5 34,5 38,5 43,0 48,0 53,0 58,0 68,0 77,5		0,5 0,75 1,0 1,25 1,25 1,5 1,5 1,5 1,5 1,5 2,0 2,0 2,5 2,5 3,0 3,0 3,0 3,0 3,0 3,0	±0.25 ±0.25 ±0.5 ±0.5 ±0.5 ±0.5 ±0.5 ±0.5 ±0.5 ±0.5 ±0.7 ±0.7 ±0.7 ±0.7 ±0.7 ±0.7 ±1.0 ±1.0 ±1.0 ±1.0	6,75 9,0 11,3 13,5 15,5 18,0 20,0 22,0 24,0 27,0 30,5 34,5 39,5 43,5 49,0 54,0 59,0 64,0 74,0 83,5	0,5 0,75 1,0 1,25 1,25 1,5 1,5 1,5 2,0 2,0 2,5 2,5 3,0 3,0 3,0 3,0	5 5 7 7 7 8 8 8 9 10 12 12 15 15 15 15	0,5 0,75 1,0 1,0 1,0 1,5 1,5 1,5 1,5 2,0 2,0 2,0 2,5 2,5 2,5 2,5	1,0 1,25 1,5 2,0 2,0 2,0 2,0 2,0 2,0 2,0 2,5 3,0 3,0 3,0 3,5 3,5 4,5 4,5	0,75 1,1 1,5 1,9 1,9 2,2 2,2 2,2 3,0 3,0 3,5 3,5 4,5 4,5 5,5 5,5
		+0,4 - 0,5
		+0,4 - 1,0
		+0,5 - 1,1

Note. At the request of the consumer, the maximum deviations of the size d1 should not exceed the maximum deviations d plus double the maximum deviations h. By agreement between the manufacturer and the consumer, it is allowed to manufacture rods from 5 to 25 m.
1.14. The limit deviations for the length of the measuring rods must correspond to those given in Table. 4

Profile number (nominal diameter dn)

d

h

d1

h1

hr

hb

t

b

b1

r

angle, deg

Rated

Previous off

Rated

Previous off

10 12 14 16 18 20 28 32 36 40

8,7 10,6 12,5 14,2 16,2 18,2 20,3 23,3 25,9 29,8 33,7 37,6

1,6 1 ,6 2,0 2,5 2,5 2,5 2,5 2,5 3,0 3,2 3,5 3,5

±0.5 ±0.5 +0,65 - 0,85 +0,65 - 0,85 +0,65 - 0,85 +0,65 - 0,85 0,65 - 0,85 +0,65 - 0,85 1,0 - 1,2 +1,0 - 1,2 +1,0 - 1,2 +1,0 - 1,2

11,9 13,8 16,5 19,2 21,2 23,2 25,3 28,3 31,9 36,2 40,7 44,6

1,6 1,6 2","0 2,5 2,5 2,5 2,5 2,5 3,0 3,2 3 5 3,5

0,6 0,6 0,8 1,0 1,0 1,0 1, 2 1,2 1,5 1,5

1,0 1,0 1,2 1,5 1,5 1,5 1,8 2,0 2,0 2,0

10 10 12 12 12 12 14 16 18 18

0,7 0,7 1,0 1,0 1,0 1,0 1,0 1,2 1,2 1,5 1,5 1,5

1,5 2,0 2,0 2,0 2,0 2,0 2,5 3,0 3,0 3,0

11 11 12 12 12 12 14 14 19 19

50

+0,4 - 0,5

Rods of increased accuracy are manufactured at the request of the consumer.
1.15. The curvature of the rods should not exceed 0.6% of the measured length.

Legend Examples

Reinforcing steel with a diameter of 20 mm, class A-II (A300): 20 - A-II GOST 5781-82

Reinforcing steel with a diameter of 18 mm, class A-I (A240): 18 - A-I GOST 5781-82.

In bar designation class A-P(A300) special purpose index c is added: Ac-II (Ac300)
(Changed edition, Rev. No. 4)

2. TECHNICAL REQUIREMENTS

2.1. Reinforcing steel is manufactured in accordance with the requirements of this standard for technological regulations approved in the prescribed manner.
2.2. Reinforcing steel is made from carbon and low-alloy steel of the grades indicated in Table. 5. The steel grade is indicated by the consumer in the order. In the absence of an indication, the steel grade is set by the manufacturer. For a rod of class A-IV (A600), steel grades are set by agreement between the manufacturer and the consumer.

Reinforcing steel class	Profile diameter, mm	steel grade
A-I (A240)	6-40	StZkp, StZps, StZsp
A-II (A300)	10-40 40-80	St5sp, St5ps 18G2S
Ac-II (Ac300)	10-32 (36-40)	10GT
A-III (A400)	6-40 6-22	35GS, 25G2S 32G2Rps
A-IV (A600)	10-18 (6-8)	80С
	10-32 (36- 40)	20ХГ2Ц
A-V (A800)	(6-8) 10-32 (36-40)	23X2G2T
A-VI (A1000)	10-22	22H2G2AYU, 22H2G2R, 20H2G2SR

1. It is allowed to manufacture reinforcing steel class A-V(A800) from steel grades 22Kh2G2AYU, 22Kh2G2R.i 20Kh2G2SR.
2. The dimensions indicated in brackets are made by agreement between the manufacturer and the consumer.
(Changed edition, Rev. No. 3, 4).

2.3. The chemical composition of reinforcing carbon steel must comply with GOST 380-88, low-alloy steel - with the standards given in tab. 6.

Steel grades	Mass fraction of elements, %
	Carbon	Manganese	Silicon	Chlorine
10GT 18G2S 32G2Rps 35GS 25G2S 20ХГ2Ц 80С 23X2G2T 22X2G2AYU 22X2G2R 20H2G2SR	Not more than 0.13 0,14-0,23 0,28-0,37 0,30-0,37 0,20-0,29 0,19-0,26 0,74-0,82 0,19-0,26 0,19- 0,26 0,19- 0,26 0,16-0,26	1,00-1,40 1,20-1,60 1,30-1,75 0,80- 1,20 1,20-1,60 1,50-1,90 0,50-0,90 1,40-1,70 1,40-1,70 1,50-1,90 1,40-1,80	0,45-0,65 0,60-0,90 Not more than 0.17 0,60-0,90 0,60-0,90 0,40-0,70 0,60-1,10 0,40-0,70 0,40-0,70 0,40-0,70 0,75-1,55	Not more than 0.30 Not more than 0.30 Not more than 0.30 Not more than.0.30 Not more than 0.30 0,90-1,20 Not more than 0.30 1,35-1,70 1,50-2,10 1,50-1,90 1,40-1,80

Steel grades	Mass fraction of elements, %
	Titanium	Zirconium	Aluminum	Nickel	Sulfur	Phosphorus	Copper
				No more
10GT 18G2S 32G2Rps 35GS 25G2S 20ХГ2Ц 80С 23X2G2T 22X2G2AYU 22X2G2R 20H2G2SR	0,015-0,03 - - - - - 0,015-0,040 0,02-0,08 0,005-0,030 0,02- 0,08 0,02-0,08	- - - - - 0,05-0,14 - - - - -	0,02-0,05 - 0,001-0,015 - - - - 0,015-0,050 0,02-0,07 0,015-0,050 6,015-0,050	- 0,30 0,30 0,30 0,30 0,30 0,30 0,30 0,30 0 ,30 0,30	0,040 0,045 0,050 0,045 0,045 0,045 0,045 0,045 0,040 0,040 0,040	0,030 0,040 0,045 0,040 0,040 0,045 0,040 0,045 0,040 0,040 0,040	0,30 0,30 0,30 0,30 0,30 0,30 0,30 0,30 0,30 0,30 0,30

2.3.1. In steel grade 20KhG2Ts, it is allowed to increase the mass fraction of chromium to 1.7% and replace zirconium by 0.02-0.08% titanium. In steel grade 23X2G2T, titanium can be replaced by 0.05-0.10%. zirconium. In this case, in the designation of steel grade 20KhG2Ts, the letter T is put instead of the letter C, and the letter T is put instead of the letter T.
In steel grade 32G2Rps, it is allowed to replace aluminum with titanium or zirconium in equal units. .
2.3.2. The mass fraction of nitrogen in steel grade 22Kh2G2AYU should be 0.015-0.030%, the mass fraction of residual nitrogen in steel grade 10GT should not exceed 0.008%.
2.3.3. The mass fraction of boron in steel grades 22Kh2G2R, 20Kh2G2SR and 32G2Rps should be 0.001-0.007%. In steel grade 22Kh2G2AYU, the addition of boron 0.001-0.008% is allowed.
2.3.4. It is allowed to add titanium to steel grades 18G2S, 25G2S, 35GS based on its mass fraction in finished rolled products 0.01-0.03%, in steel grade 35GS based on its mass fraction in finished rolled products made in coils, 0.01-0 .06%.
2.4 Deviations in chemical composition in finished rolled products from carbon steels - according to GOST 380-88, from low-alloy steels subject to the standards of mechanical properties - according to table. 7. Minus deviations in the content of elements (except for titanium and zirconium, and silicon for steel grade 20Kh2G2SR) are not limited.

Note.

By agreement between the manufacturer and the consumer, steel can be produced with other deviations in the content of chromium, silicon and manganese.
(Changed edition, Rev. No. 3).

2.6. Reinforcing steel of classes A-I (A240), A-II (AZOO), A-III (A400), A-IV (A600) is produced by hot-rolled class. A-V (A800) - with low-temperature tempering, class A-VI (A1000) - with low-temperature tempering or thermomechanical processing in the flow of a rolling mill.
It is allowed not to carry out low-temperature tempering of steel classes A-V(A800) and A-VI (A1000) subject to obtaining a relative elongation of at least 9% and a uniform elongation of at least 2% when tested for 12 hours after rolling.
2.6. The mechanical properties of reinforcing steel must comply with the standards specified in table. 8.
For steel of class AII (A300) with a diameter of more than 40 mm, a decrease in relative elongation by 0.5% is allowed for each millimeter of diameter increase, but not more than 3%.
For steel of class Ac-II (Ac300), is it possible to reduce the tensile strength to 426 MPa (43.5 kgf / mm 2) with a relative elongation? 5 30% or more.
For steel grade 25G2S of class A-III (A400), it is allowed to reduce the tensile strength to 560 MPa (57 kgf / mm 2) with a yield strength of at least 405 MPa (41 kgf / mm 2), relative elongation? 5 not less than 20%.
2.7. Statistical indicators of the mechanical properties of rods, reinforcing steel of a periodic profile must comply with Appendix 1, with increased uniformity of mechanical properties - Appendix 1 and Table. nine.
The probability of ensuring the mechanical properties specified in Table 8 must be at least 0.95.
(Revised edition, Rev. No. 3).
2.8. On the surface of the profile, including the surface of the ribs and protrusions, there should be no rolled cracks, stress cracks, flaws, rolling captivity and sunsets.
Minor damage to the ribs and protrusions is allowed, in the amount of not more than three per 1 m of length, as well as minor, rust, individual rolled dirt, prints, sagging, traces of rolled bubbles, ripples and scaly within the allowable deviations in size.
(Revised edition, Rev. No. 2).
2.9. The weldability of reinforcing steel of all grades, except for 80C, is provided by the chemical composition and manufacturing technology.
2.10. Carbon equivalent C eq ? C + Mn / 6 + Si / 10 for welded rod reinforcement from low-alloy steel class-A-III (A400) should be no more than 0.62.
(Introduced additionally, Rev. No. 5).

Class reinforcing become	Yield strength ? T		Temporary resistance break ? B		Relative extension ? 5 , %	uniform elongation ? p, %	percussion viscosity at temperature - 60 °С		Test for bend in the cold condition (c - mandrel thickness, d - rod diameter)
	N/mm 2	kgf/mm 2	N/mm 2	kgf/mm 2			MJ/m2	kgf * m / cm 2
	at least
A-I (A240) A-II (A300) Ac-II (A300) A-II (A400) A-IV (A600) A-V (A800) A-VI (A1000)	235 295 295 390 590 785 980	24 30 30 40 60 80 100	373 490 441 590 883 1030 1230	38 50 45 60 90 105 125	25 19 25 14 6 7 6	- - - - 2 2 2	- - 0,5 - - - -	- - 5 - - - -	180°; c=d 180°; c=3d 180°; c=d 90°; c=3d 45°; c=5d 45°; c=5d 45°; c=5d

Notes:

1. By agreement between the manufacturer and the consumer, it is allowed not to test the impact strength of the reinforcing steel of class Ac-II.
2. (Deleted, Rev. No. 3).
3. For reinforcing steel of class A-IV with a diameter of 18 mm of steel grade 80C, the cold bending rate is set at least 30 °.
4. For reinforcing steel of class A-I (A240) with a diameter of more than 20 mm when cold bent at 180 ° c \u003d 2 d, class A-II (A300) with a diameter of more than 20 mm c \u003d 4 d.
5. Symbols of the class of reinforcing steel according to the yield strength are indicated in brackets.
(Changed edition, Rev. No. 1, 3, 5).

Class reinforcing become	Number profile	S		So		S/x 1		So/x2
		For? T (? 0,2)	For? B	For? T (? 0,2)	For? B	For? T (? 0,2)	For? B	For? T (? 0,2)	For? B
		MPa (kgf / mm 2)		MPa (kgf / mm 2)
		no more
A-II (A300) A-II (A400) A-IV (A600) A-V (A800) A-VI (A1000)	10-40 6-40 10-32 10-32 10-32	29(3) 39(4) 69(7) 78(8) 88(9)	29(3) 39(4) 69(7) 78(8) 88(9)	15(1,5) 20(2,0) 39(4) 49(5) 49(5)	15(1,5) 20(2,0) 39(4) 49(5) 49(5)	0,08 0,08 0,09 0,09 0,08	0,06 0,07 0,07 0,07 0,07	0,05 0,05 0,06 0,05 0,05	0,03 0,03 0,05 0,05 0,04

Note.

1. S - standard deviation in the general population of tests,
So - standard deviation in the heat batch,
x 1 - the average value in the general population of tests;
x 2 - the minimum average value in the heat batch.
2. For reinforcing steel in coils with a diameter of 6 and 8 mm, it is allowed to increase the standards for S and So by 4.9 MPa (0.5 kgf / mm 2),
3. (Deleted, Rev. No. 5).

3. ACCEPTANCE RULES

3.1. Reinforcing steel is accepted in batches consisting of profiles of the same diameter, one class of one melting ladle and issued with one quality document.
The mass of the batch must be up to 70 tons.
It is allowed to increase the mass of the batch up to the mass of the melting ladle.
3. 2. Each batch is accompanied by a quality document in accordance with GOST 7566-81 with additional data:
profile number;
Class;
minimum mean x 2 and standard deviations S 0 in the batch of values? T(?0.2) and? B;
cold bend test results;
values ​​of uniform elongation for steel class A - IV (A600), A-V (800), A-VI (A1000).
3. 3. To check the dimensions and quality of the surface, select:
in the manufacture of reinforcing steel in rods - at least 5% of the batch;
when manufactured in skeins - two skeins from each batch.
(Revised edition, Rev. No. 3).
3 4. To check the chemical composition, samples are taken according to GOST 7565-81.
The manufacturer determines the mass fraction of aluminum periodically, but at least once a quarter.
3.5. To test for tension, bending and impact strength, two rods are selected from the batch
For the manufacturer, the interval for the selection of rods must be at least half the time spent on rolling one profile size of one batch
(Revised edition, Rev. No. 3).
3 6 Upon receipt of unsatisfactory test results for at least one of the indicators, repeated tests are carried out in accordance with GOST 7566-81.

4. TEST METHODS

4. 1. Chemical analysis of steel is carried out according to GOST 12344-88, GOST 12348-78, GOST 12350-78, GOST 12352-81, GOST 12355-78, GOST 12356-81, GOST 18895-81 or other methods that provide the required accuracy .
4. 2. The diameter and ovality of the profiles are measured at a distance of at least 150 mm from the end of the rod or at a distance of at least 1500 mm from the end of the coil with a coil mass of up to 250 kg and at least 3000 mm with a coil mass of more than 250 kg.
4. 3. Dimensions are checked with a measuring tool of the required accuracy.
4. 4. One sample is cut from each selected rod for tensile, bending and impact testing.
4.5. Sampling for tensile, bending and impact strength testing is carried out according to GOST 7564-73
4.6. The tensile test is carried out according to GOST 12004-81.
4.7. The bending test is carried out according to GOST 14019-80 on samples with a cross section equal to the cross section of the rod
For rods with a diameter of more than 40 mm, it is allowed to test samples cut along the axis of the rod, on a mandrel, with a diameter reduced by half compared to that indicated in Table. 4 with a bending force applied from the side of the cut.
4.8. Determination of impact strength is carried out according to GOST 9454-78 on samples with a concentrator type U type 3 for rods with a diameter of 12-14 mm and type 1 samples for rods with a diameter of 16 mm or more. Samples are made in accordance with the requirements of GOST 9454-78.
4.9. It is allowed to apply statistical and non-destructive methods of control of mechanical properties and mass of profiles.
4.10. The curvature of the rods is measured on the length of the delivered profile, but not shorter than 1m.
4.11. Determination of statistical indicators of mechanical properties in accordance with the mandatory Appendix 2.
4.12. The quality of the surface is checked without the use of magnifying instruments.
4.10-4.12. (Introduced additionally, Amendment No. 3).
4.13. The measurement of the height of the transverse protrusions of a periodic profile should be carried out along the vertical axis of the cross section of the reinforcing bar.
(Introduced additionally, Rev. No. 4).

5. PACKAGING, LABELING, TRANSPORT AND STORAGE

5.1. Packing, marking, transportation and storage - in accordance with GOST 7566-81 with additions: .
the ends of the rods of low-alloy steels of class A-IV (A600) must be painted red, class A-V - red and green, class A-VI (A1000) - red and blue. It is allowed to color the bundles at a distance of 0.5 m from the ends;

the rods are packed in bundles weighing up to 15 tons, tied with wire or rolled wire. At the request of the consumer, the rods are packed in bundles weighing up to 3 and 5 tons.

On ligaments, the paint is applied in stripes with a width of at least 20 mm on the side surface along the circumference (at least 1/2 of the circumference) at a distance of not more than 500 mm from the end.

The paint is applied to the coils in strips with a width of at least 20 mm across the coils from the outside of the coil.
On unpackaged products, paint is applied to the end or to the side surface at a distance of not more than 500 mm from the end.
On the label attached to each bunch of rods, the accepted designation of the class of reinforcing steel (for example, A-III) or the symbol of the class according to the yield strength (A400) is applied.
(Changed edition, Rev. No. 3, 5).

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HOT ROLLED STEEL
FOR REINFORCEMENT
REINFORCED CONCRETE STRUCTURES

TECHNICAL CONDITIONS

Date of introduction 01.07.83

This standard applies to hot-rolled round steel of a smooth and periodic profile, intended for the reinforcement of conventional and prestressed concrete structures (reinforcing steel).

In terms of the norms for the chemical composition of low-alloy steels, the standard also applies to ingots, blooms and billets.

(Revised edition, Rev. No. 4).

1. CLASSIFICATION AND ASSORTMENT

1.1. Depending on the mechanical properties, reinforcing steel is divided into classes A-I (A240), A-II (A300), A-III (A400), A-IV (A600), A-V (A800), A-VI (A1000).

1.2. Reinforcing steel is produced in rods or coils. Reinforcing steel of class A-I (A240) is made smooth, classes A-II (A300), A-III (A400), A-IV (A600), A-V (A800) and A-VI (A1000) - a periodic profile.

At the request of the consumer, steel of classes A-II (A300), A-III (A400), A-IV (A600) and A-V (A800) is made smooth.

1.1, 1.2. (Changed edition, Rev. No. 5).

1.3. Profile numbers, cross-sectional areas, weight of 1 m length of reinforcing steel of a smooth and periodic profile, as well as maximum mass deviations for periodic profiles must correspond to those indicated in Table. one.

Table 1

Profile number (nominal rod diameter d n)	Cross section rod section, cm 2	Weight 1 m profile
		Theoretical; kg	Limit deviations, %

1.4. The nominal diameters of periodic profiles must correspond to the nominal diameters of smooth profiles of equal cross-sectional area.

1.5. The mass of 1 m of the profile is calculated from nominal dimensions with a steel density of 7.85 × 10 3 kg/m 3 . The probability of providing a mass of 1 m must be at least 0.9.

(Revised edition, Rev. No. 3).

1.6. Limit deviations of the diameter of smooth profiles must comply with GOST 2590 for normal rolling accuracy.

1.7. Reinforcing steel of a periodic profile is a round profile with two longitudinal ribs and transverse ledges running along a three-start helix. For profiles with a diameter of 6 mm, protrusions running along a single-start helix are allowed, with a diameter of 8 mm - along a two-start helix.

1.8. Reinforcing steel of class A-II (A300), made in the usual version, with a profile shown in Fig. one a, and special purpose Ac-II (Ac300) with a profile shown in Fig. 2 but, must have protrusions running along helical lines with the same lead on both sides of the profile.

Steel class A-III (A400), manufactured by the profile shown in Fig. one b, and classes A-IV (A600), A-V (A800), A-VI (A1000) with the profile shown in Fig. one b, 2b, should have protrusions along helical lines, having right-handed on one side of the profile, and left-handed entries on the other.

Reinforcing steel for special purposes of class Ac-II (Ac300) is made with profiles shown in Fig. one a or 2 but.

The profile shown in hell. 2 but, special purpose are manufactured by agreement between the manufacturer and the consumer. The shape and dimensions of the profiles shown in Fig. 2 but, b, can be specified.

1.9. Dimensions and limit deviations of the dimensions of reinforcing steel of a periodic profile, manufactured according to the drawing. one a, b, must correspond to those given in Table. 2, but damn. 2 but, b- given in table. 3.

table 2

Dimensions, mm

Profile number (nominal diameter d n)
		Previous off		Previous off
Note. At the request of the consumer, limit deviations of the size d1 must not exceed the limit deviations d plus twice the limit deviations h.

Table 3

Dimensions, mm

Profile number (nominal diameter d m)

Previous off

Previous off

1.10. Relative displacements of helical protrusions along the sides of the profile, separated by longitudinal ribs, are not standardized.

Dimensions for which limit deviations are not set are given for building a gauge and are not checked on the finished profile.

1.11. The ovality of smooth profiles (the difference between the largest and smallest diameters in one section) should not exceed the sum of the plus and minus limit deviations in diameter.

1.9 - 1.11. (Revised edition, Rev. No. 3).

1.12. Reinforcing steel of classes A-I (A240) and A-II (A300) with a diameter of up to 12 mm and class A-III (A-400) with a diameter of up to 10 mm inclusive. are made in coils or rods, large diameters - in rods. Reinforcing steel of classes A-IV (A600), A-V (A800) and A-VI (A1000) of all sizes is produced in rods with a diameter of 6 and 8 mm - by agreement between the manufacturer and the consumer in coils.

1.13. Rods are made from 6 to 12 m long:

Measured length;

Measured length with random lengths of at least 2 m, not more than 15% of the batch weight;

Unmeasured length.

In a batch of rods of random length, rods with a length of 3 to 6 and not more than 7% of the mass of the batch are allowed.

By agreement between the manufacturer and the consumer, it is allowed to manufacture rods with a length of 5 to 25 m.

1.14. Limit deviations along the length of the measuring rods must correspond to those given in table. 4.

Table 4

Rods of increased accuracy are manufactured at the request of the consumer.

1.15. The curvature of the rods should not exceed 0.6% of the measured length.

Legend Examples

Reinforcing steel with a diameter of 20 mm, class A-II (A300):

The same, with a diameter of 18 mm, class A-I (A240):

In the designation of rods of class A-II (A300) for special purposes, the index "c" is added: Ac-II (Ac300).

(Revised edition, Rev. No. 4).

2. TECHNICAL REQUIREMENTS

2.1. Reinforcing steel is manufactured in accordance with the requirements of this standard according to the technological regulations approved in the prescribed manner.

2.2. Reinforcing steel is made from carbon and low-alloy steel of the grades indicated in Table. 5. The steel grade is indicated by the consumer in the order. In the absence of an indication, the steel grade is set by the manufacturer. For class A-IV (A600) rods, steel grades are set by agreement between the manufacturer and the consumer.

Table 5

Reinforcing steel class	Profile diameter, mm	steel grade	Reinforcing steel class	Profile diameter, mm	steel grade
		St3kp, St3ps, St3sp
		St5sp, St5ps
Ac-II (Ac300)
					22H2G2AYU, 22H2G2R,
Notes: 1. It is allowed to manufacture reinforcing steel of class A-V (A800). From steel grades 22Kh2G2AYU, 22Kh2G2R and 20Kh2G2SR. 2. The dimensions indicated in brackets are made by agreement between the manufacturer and the consumer.

(Changed edition, Rev. No. 3, 4).

2.3. The chemical composition of reinforcing carbon steel must comply with GOST 380, low-alloy steel - with the standards given in table. 6.

Table 6

Markf steel	Mass fraction of elements, %
		Manganese				Zirconium	Aluminum
	Not more than 0.13			Not more than 0.30
			Not more than 0.17
				Not more than 0.30

2.3.1. In steel grade 20KhG2Ts, it is allowed to increase the mass fraction of chromium to 1.7% and replace zirconium by 0.02 - 0.08% titanium. In steel grade 23Kh2G2T, titanium can be replaced by 0.05 - 0.10% zirconium. In this case, in the designation of steel grade 20KhG2Ts, the letter T is put instead of the letter C, and the letter T is put instead of the letter T.

In steel grade 32G2Rps, it is allowed to replace aluminum with titanium or zirconium in equal units.

2.3.2. The mass fraction of nitrogen in steel grade 22Kh2G2AYU should be 0.015 - 0.030%, the mass fraction of residual nitrogen in steel grade 10GT should not exceed 0.008%.

2.3.3. The mass fraction of boron in steel grades 22Kh2G2R, 20Kh2G2SR and 32G2Rps should be 0.001 - 0.007%. In steel grade 22Kh2G2AYU, the addition of boron 0.001 - 0.008% is allowed.

2.3.4. It is allowed to add titanium to steel grades 18G2S, 25G2S, 35GS based on its mass fraction in finished rolled products 0.01 - 0.03%, in steel grade 35GS based on its mass fraction in finished rolled products made in coils, 0.01 - 0 .06%.

2.4. Deviations in chemical composition in finished rolled products from carbon steels - according to GOST 380, from low-alloy steels, subject to the standards of mechanical properties - according to table. 7. Minus deviations in the content of elements (except for titanium and zirconium, and for steel grade 20Kh2G2SR - silicon) are not limited.

Table 7

	Previous off, %		Previous off, %
Manganese		Zirconium
Note. By agreement between the manufacturer and the consumer, steel can be produced with other deviations in the content of chromium, silicon and manganese.

(Revised edition, Rev. No. 3).

2.5. Reinforcing steel of classes A-I (A240), A-II (A300), A-III (A400), A-IV (A600) is made hot-rolled, class AV (A800) - with low-temperature tempering, class A-VI (A1000) - with low-temperature tempering or thermomechanical treatment in the flow of a rolling mill.

It is allowed not to carry out low-temperature tempering of steel classes A-V(A800) and A-VI (A1000) subject to obtaining a relative elongation of at least 9% and a uniform elongation of at least 2% when tested for 12 hours after rolling.

2.6. The mechanical properties of reinforcing steel must comply with the standards specified in table. 8.

Table 8

Reinforcing steel class	Yield strength s t		Tensile strength s in		Relative elongation d 5 %	Uniform elongation d r , %		Impact strength at -60 °C		Bending and cold test ( from- mandrel thickness, d- rod diameter)
									kgf × m / cm 2
										180°; c = d
										180°; from = 3d
Ac-II (Ac300)										180°; c = d
										90°; from = 3d
										45°; from = 5d
Notes: 1. By agreement between the manufacturer and the consumer, it is allowed not to test the impact strength of the reinforcing steel of class Ac-II. 2. (Deleted, Rev. No. 3). 3. For reinforcing steel of class A-IV with a diameter of 18 mm of steel grade 80C, the bending rate in the cold state is set at least 30 °. 4. For reinforcing steel class A-I (A240) with a diameter of more than 20 mm when cold bent by 180 ° from = 2d, class A-II (A300) with a diameter of St. 20 mm from = 4d. 5. In parentheses are the symbols for the yield strength.

(Changed edition, Rev. No. 1, 3, 5).

For steel class A-II (A300) with a diameter of St. 40 mm, a decrease in relative elongation by 0.25% for each millimeter of diameter increase is allowed, but not more than 3%.

For steel of class Ac-II (Ac300), it is allowed to reduce the tensile strength to 426 MPa (43.5 kgf / mm 2) with a relative elongation: d 5 30% or more.

For steel grade 25G2S of class A-III (A400), the tensile strength can be reduced to 560 MPa (57 kgf / mm 2) with a yield strength of at least 405 MPa (41 kgf / mm 2), relative elongation d 5 of at least 20%.

2.7. Statistical indicators of the mechanical properties of bars of reinforcing steel of a periodic profile must comply with Appendix 1, with increased uniformity of mechanical properties - Appendix 1 and Table. nine.

The probability of providing the mechanical properties specified in table. 8 must be at least 0.95.

(Revised edition, Rev. No. 3).

2.8. On the surface of the profile, including the surface of the ribs and protrusions, there should be no rolled cracks, stress cracks, flaws, rolling captivity and sunsets.

Minor damage to the ribs and protrusions is allowed, in the amount of not more than three per 1 m of length, as well as slight rust, individual rolled dirt, prints, sagging, traces of rolled bubbles, ripples and scaly within the allowable deviations in size.

(Revised edition, Rev. No. 2).

2.9. The weldability of reinforcing steel of all grades, except for 80C, is provided by the chemical composition and manufacturing technology.

2.10. The carbon equivalent for welded rod reinforcement from low-alloy steel of class A-III (A400) should be no more than 0.62.

(Introduced additionally, Rev. No. 5).

Table 9

Reinforcing steel class	Profile number
		For s t (s 0.2)		For s t (s 0.2)		For s t (s 0.2)		For s t (s 0.2)
		MPa (kgf / mm 2)		MPa (kgf / mm 2)
Notes: 1. S- standard deviation in the general population of tests; S 0 - standard deviation in the party-smelting; Average value in the general population of tests; The minimum average value in the heat batch. 2. For reinforcing steel in coils with a diameter of 6 and 8 mm, it is allowed to increase the standards for S And S 0 by 4.9 MPa (0.5 kgf / mm 2). 3. (Deleted, Rev. No. 5).

3. ACCEPTANCE RULES

3.1. Reinforcing steel is accepted in batches consisting of profiles of the same diameter, one class, one melting ladle and issued with one quality document.

The mass of the batch must be up to 70 tons.

It is allowed to increase the mass of the batch up to the mass of the melting ladle.

3.2. Each batch is accompanied by a quality document in accordance with GOST 7566 with additional data:

Profile number;

Minimum mean and standard deviations S 0 in the batch of values ​​s t (s 0.2) and s in;

Cold bend test results;

Uniform elongation values ​​for steel grades A-IV (A600), A-V (A800), A-VI (A1000).

3.3. To check the dimensions and surface quality, select:

In the manufacture of reinforcing steel in rods - at least 5% of the batch;

In the manufacture and skeins - two skeins from each batch.

(Revised edition, Rev. No. 3).

3.4. To check the chemical composition, samples are taken according to GOST 7565.

The manufacturer determines the mass fraction of aluminum periodically, but at least once a quarter.

3.5. To test for tension, bending and impact strength, two rods are selected from the batch.

For the manufacturer, the interval for the selection of rods must be at least half the time spent on rolling one profile size of one batch.

(Revised edition, Rev. No. 3).

3.6. Upon receipt of unsatisfactory test results for at least one of the indicators, repeated tests are carried out in accordance with GOST 7566.

4. TEST METHODS

4.1 Chemical analysis of steel is carried out in accordance with GOST 12344, GOST 12348, GOST 12350, GOST 12352, GOST 12355, GOST 12356, GOST 18895 or other methods that provide the required accuracy.

4.2. The diameter and ovality of the profiles are measured at a distance of at least 150 mm from the end of the rod or at a distance of at least 1500 mm from the end of the coil with a coil mass of up to 250 kg and at least 3000 mm with a coil mass of more than 250 kg.

4.3. Dimensions are checked with a measuring tool of the required accuracy.

4.4. One sample is cut from each selected rod for tensile, bending and impact testing.

4.5. Sampling for tensile, bending and impact testing is carried out according to GOST 7564.

4.6. The tensile test is carried out according to GOST 12004.

4.7. The bending test is carried out according to GOST 14019 on samples with a cross section equal to the cross section of the rod.

For rods with a diameter of more than 40 mm, it is allowed to test samples cut along the axis of the rod, on a mandrel, with a diameter reduced by half compared to that indicated in Table. 4 with a bending force applied from the side of the cut.

4.8. Determination of impact strength is carried out according to GOST 9454 on samples with a concentrator type U type 3 for rods with a diameter of 12 - 14 mm and type 1 samples for rods with a diameter of 16 mm or more. Samples are made in accordance with the requirements of GOST 9454.

4.9. It is allowed to use statistical and non-destructive methods to control the mechanical properties and mass of profiles.

4.10. The curvature of the rods is measured on the length of the supplied profile, but not shorter than 1 m.

4.11. Determination of statistical indicators of mechanical properties in accordance with the mandatory Appendix 2.

4.12. The quality of the surface is checked without the use of magnifying instruments.

4.10 - 4.12. (Introduced additionally, Rev. No. 3).

4.13. The measurement of the height of the transverse protrusions of a periodic profile should be carried out along the vertical axis of the cross section of the reinforcing bar.

(Introduced additionally, Rev. No. 4).

5. PACKAGING, LABELING, TRANSPORT AND STORAGE

5.1. Packing, marking, transportation and storage - according to GOST 7566 with the following additions:

The ends of rods made of low-alloy steels of class A-IV (A600) must be painted with red paint, class A-V - red and green, class A-VI (A1000) - red and blue. It is allowed to color the bundles at a distance of 0.5 m from the ends;

The rods are packed in bundles weighing up to 15 tons, tied with wire or rolled wire. At the request of the consumer, the rods are packed in bundles weighing up to 3 and 5 tons;

The paint is applied to the ligaments in stripes with a width of at least 20 mm on the side surface around the circumference (at least 1/2 of the circumference) at a distance of not more than 500 mm from the end.

The paint is applied to coils in strips with a width of at least 20 mm across the coils from the outside of the coil.

On unpackaged products, paint is applied to the end or to the side surface at a distance of not more than 500 mm from the end.

On the label attached to each bunch of rods, the accepted designation of the class of reinforcing steel (for example, A-III) or the class symbol for the yield strength (A400) is applied.

(Changed edition, Rev. No. 3, 5).

ATTACHMENT 1
Mandatory

REQUIREMENTS FOR STATISTICAL INDICATORS OF MECHANICAL PROPERTIES

1. The manufacturer guarantees the consumer the average values ​​of tensile strength s in and yield strength (physical s t and conditional s 0.2) in the general population - and the minimum average values ​​of the same indicators in each heat batch, the values ​​​​of which are established from the conditions:

³ Х i b p + t × S;

> 0,9Х i b p + 3 S 0 ;

³ Х i b p ,

where Х i b p- rejection values ​​\u200b\u200bof the values ​​\u200b\u200bof s in, s 0.2 indicated in table. 8 of this standard;

t- the value of the quantile, taken equal to 2 for classes A-II (A300) and A-III (A400) and 1.64 - for classes A-IV (A600), A-V (A800) and A-VI (A 1000).

2. Quality control of indicators of mechanical properties of products at the manufacturing plant

2.1. The required quality indicators of profiles are ensured by compliance with the production technology and controlled by testing in accordance with the requirements of clause 3.5, clauses. 4.4 - 4.8.

2.2. The values ​​are set in accordance with the test results and the provisions of Annex 2.

3. Quality control of indicators of mechanical properties of products at the consumer enterprise

3.1. The consumer in the presence of a document on the quality of the products the highest category quality may not test mechanical properties.

3.2. If it is necessary to check the mechanical properties of each batch, six samples are tested, taken from different packages or coils and from different profiles, and according to the results, the fulfillment of the conditions is checked.

where is the average value of mechanical properties based on the results of tests of six samples;

X min - the minimum value of the test results of six samples.

3.3. The minimum values ​​of relative elongation d 5 and uniform elongation d r must be at least the values ​​given in table. 8.

(Revised edition, Rev. No. 3).

APPENDIX 2
Mandatory

METHODOLOGY
determination of statistical indicators of strength characteristics of mechanical properties
hot-rolled steel for reinforcing reinforced concrete structures

This technique applies to hot-rolled, accelerated-cooled, thermomechanically and thermally hardened rolled products of a periodic profile made in coils or rods.

The technique is used in assessing the reliability of mechanical properties in each batch-melting and steel as a whole, monitoring the stability of the technological process.

1. To determine the statistical indicators of mechanical properties (physical yield strength s t or conditional s 0.2, tensile strength s in), control test results are used, called general populations.

2. Compliance of the mechanical properties of rolled products with the requirements of regulatory and technical documentation is determined on the basis of statistical processing of test results that form a sample from the general population. All conclusions, results and conclusions made on the basis of the sample refer to the entire population.

3. Sample - a set of results of control tests, forming an information array to be processed.

The sample includes the results of commissioning tests of rolled products of one class, one brand and smelting method, rolled to one or groups of similar profile sizes.

4. The sample on the basis of which statistical indicators are calculated must be representative and cover a sufficiently long period of time, but not less than three months, during which technological process do not change. If necessary, the time interval for sampling can be increased. Checking the homogeneity of the sample - according to the normative and technical documentation.

5. The number of melting parties in each sample must be at least 50.

6. When forming a sample, the condition of random sampling from a heat batch must be observed. The assessment of the abnormality of the test results is carried out according to the regulatory and technical documentation.

7. During statistical processing, the average value, standard deviation is determined S each sample (general population), the standard deviation within the party-smelting S 0 , as well as the standard deviation of melting averages S one . Value S 1 is determined by the formula

quantities, S determined according to the normative and technical documentation.

8. Stability test and S carried out in accordance with OST 14-34.

9. Size S 0 is determined for accelerated-cooled, thermomechanically and thermally hardened reinforcing steel only by the experimental method, for hot-rolled - by the experimental method and the swing method according to the formula, where and S w - respectively, the average value and standard deviation of the range distribution for two tests from the party.

Minimum value S 0 is equal to 1.

10. Determining the value S 0 is experimentally produced on at least two heats for each steel grade, class and size profile of rolled products by random sampling of at least 100 samples from each heat.

11. The value of the minimum average value of the strength characteristics s t (s 0.2), s c) in each batch-melting is determined from the condition where t- quantile value 1.64 for probability 0.95.

12. The minimum value of the results of tensile tests of two samples ( n= 2) each batch subjected to control must have at least X min , determined by the formula

13. To provide a guarantee to the consumer of mechanical properties, the following conditions must be met:

where Х i br - rejection value s t (s 0.2) and s in, specified in the relevant regulatory and technical documentation.

(Introduced additionally, Rev. No. 3).

INFORMATION DATA

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

2. APPROVED AND INTRODUCED BY Decree of the USSR State Committee for Standards dated 17.12. No. 4800

4. REFERENCE REGULATIONS AND TECHNICAL DOCUMENTS

Annex 2

5. The limitation of the validity period was removed according to the protocol No. 3-93 of the Interstate Council for Standardization, Metrology and Certification (IUS 5-6-93)

6. EDITION (November 2005) with Amendments No. 1, 2, 3, 4, 5, approved in February 1984, June 1987, December 1987, October 1989, December 1990 (5- 84, 11-87, 3-88, 1-90, 3-91).

It is mandatory to apply metal fittings. GOST 5781-82 specifications this material handles quite definitely. The fittings must be, firstly, durable, and secondly, resistant to corrosion and durable.

This element allows you to build much more reliable foundations, ceilings and other similar structures. The fact is that concrete has a very high compressive strength, but not in tension. The main task of reinforcement is to prevent the destruction of structures during various kinds of movements.

Types of rods

Regulates the standards of such a common building material, as fittings, GOST 5781-82. Its technical characteristics may be different. Armature is classified as follows:

AI - smooth round profile;

AII, AIII, A IV, AV and AVI - periodic corrugated profile.

According to the method of manufacturing reinforcement is:

hot-rolled (rod);

cold-drawn (wire).

In addition to metal, fiberglass rods of this type are also produced in our time. According to the principle of operation, a distinction is also made between prestressed and conventional reinforcement. In addition, there are several types of similar rods, classified by purpose:

• distribution;

  mounting.

According to the installation method, the fittings are welded or knitted.

Other classification

At the moment, there is a slightly different division of reinforcement into groups:

A1. The fittings smooth of this variety are made of high-quality low-alloy steel. Sometimes a rod of this brand is also made from cold-drawn wire. The main advantage is that it can be used in absolutely any environment.

A500S. This kind of bars can have a periodic or round profile. Depending on the quality of the steel used for the manufacture, these bars are divided into different classes. The main purpose of A500S fittings is to fix ordinary concrete products.

B500C. This type of rod is used mainly in monolithic construction, for the manufacture of various kinds of durable hooks, and differs from this group primarily in that it is not hot-rolled, but cold-formed.

25G2S. The main advantages of this type of bars are high degree strength, reliability and durability. Reinforcement of this class can be used both in the manufacture of secondary reinforced concrete structures and load-bearing ones. The corrugation of the rods of this brand has its own characteristics and allows for the strongest adhesion to concrete.

35GS. This specialized fitting is made from the highest quality steel and is available in both round and corrugated surfaces. It is used mainly in the construction of critical structures made of reinforced concrete.

Rebar range

Thus, it regulates exactly the quality and GOST 5781-82. The table below clearly demonstrates the ratio of the cross-sectional area of ​​the bars and their weight.

Bar profile number	Sectional area of ​​the bar	Weight

Below you can see how the GOST 5781-82 rebar assortment is determined in terms of the ratio between diameter and weight. The table shows this more than clearly.

Class	steel grade	Diameter (mm)
	St3kp, St3ps, St3sp
	St5sp, 18G2S, St5ps	10 to 40 and 40 to 80
	35GS, 32G2Rps, 25G2S

Classes of specialized fittings

Bars made from special steel grades are marked with letters so that the consumer can determine specific area their applications. The class of reinforcement GOST 5781-82 in this case defines as follows:

"T"- this is how corrosion-resistant fittings are marked, which can also be used in humid climates;

"FROM"- bars that can be welded;

"IN"- Reinforced fittings.

Color coding

Actually, you can define it in a slightly different way. So that no one has any questions about the type of bars, they are marked at the ends with paint. So, AIV material is marked in red, AIII in yellow, AV and VI in blue. According to the standards, it is allowed to paint rods on ribs up to 0.5 m from their ends.

Main area of ​​use

Thus, the manufacture of various kinds of reinforced concrete structures is what reinforcement can be used for. GOST 5781-82 defines the technical characteristics of this material, as we found out, exactly. Depending on the specific properties, such metal rods can be used for:

pouring foundations;

cover manufacturing:

building bridges;

road construction;

in the laying of gas and foam concrete blocks.

Smooth reinforcement is most often used only to give a concrete product a certain shape. Ribbed is used to evenly distribute the load. Before pouring concrete, the rebar is usually assembled into a strong frame. At the same time, both welding and special knitting wire can be used to connect the elements.

Profile

Reinforcement with a smooth matte surface along the entire length is called smooth. Also, the profile of the bars is: