Reinforcing steel A3 GOST 5781 82. Hot-rolled steel for reinforcing reinforced concrete structures

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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 ordinary 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 class A-I(A240) are 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
Profile number (nominal rod diameter d n)	Cross section rod section, cm 2	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-II I (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)
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

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 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
		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
		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 processing in the flow of the 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)
			Relative elongation d 5 %	Uniform elongation d r , %		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), 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 d 5 of at least 20%.

2.7. Statistical indicators of the mechanical properties of rods 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. Weldability of reinforcing steel of all grades, except 80C, is ensured 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 quality document for products of the highest quality category, may not conduct tests of 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).

STATE STANDARD OF THE UNION OF THE SSR

HOT-ROLLED STEEL FOR REINFORCEMENT OF REINFORCED CONCRETE STRUCTURES

Specifications

GOST 5781-82

PUBLISHING STANDARDS

Moscow

STATE STANDARDSOYUZ SSR

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

In terms of the standards 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) - periodic profile.

At the request of the consumer, steel of classes A-II (A300), A-III (A400), A-IV (A600) and A-V (A1000) is made smooth.

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

1.3. Numbers of profiles, 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 1.

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

Table 1

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

1.5. The mass of 1 m of the profile is calculated according to the nominal dimensions with a steel density equal to 7.85 × 10 3 kg / m 3. The probability of ensuring the mass of 1 m should be at least 0.9.

(Changed edition, Rev. No. 3).

1.6. Limit deviations of the diameter of smooth profiles must comply with GOST 2590-88 for normal rolling accuracy.

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 the profiles shown in Fig. one a or 2 but.

The profile shown in hell. 2 but, special purpose is manufactured by agreement between the manufacturer and the consumer. The shape and dimensions of the profiles shown in Fig. 2 but And 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 And b, must correspond to those given in Table. 2, but handwriting. 2 but And b- given in table. 3.

table 2

Dimensions, mm

Profile number (nominal diameter d n)			b 1
	Previous off	Previous off

Note. At the request of the consumer, the maximum deviations of the size d 1 must not exceed the limit deviations d plus twice the limit deviations h.

Table 3

Dimensions, mm

Profile number (nominal diameter dn)

r 1

a,
hail

Previous off

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

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 of the subdiameter.

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 produced 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, is 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 non-dimensional segments with a length of at least 2 m, not more than 15% of the batch weight;

unmeasured length.

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

By agreement between the manufacturer and the consumer, it is allowed to manufacture rods from 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):

20-A-II(A300)GOST 5781-82

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

18- A- I(A240) GOST 5781-82

In the designation of rods of class A-II for special purposes, an index is added with: Ac-II.

(Changed 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-VI (A-1000) rods, steel grades are established by agreement between the manufacturer and the consumer.

Table 5

Reinforcing steel class	Profile diameter, mm	steel grade
		St3kp, St3ps, St3sp
		St5sp, St5ps

Ac-II (Ac300)










		22H2G2AYU, 22H2G2R, 20H2G2SR

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 380-88, low-alloy steel - with the standards given in Table 6.

Table 6

Steel grades	Mass fraction of elements, %
	Manganese
	Not more than 0.13		Not more than 0.30
			Not more than 0.30
		Not more than 0.17	Not more than 0.30
			Not more than 0.30
			Not more than 0.30

			Not more than 0.30

Continuation of the table. 6

Steel grades	Mass fraction of elements, %
	Zirconium	Aluminum

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 T, 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 22Kh2G2A10 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%, to 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. Negative deviations in the content of elements (except for titanium and zirconium, and for steel grade 20Kh2G2SR silicon) are not limited.

Table 7

Note. By agreement between the manufacturer and the consumer, steel can be manufactured with other deviations in the content of chromium, silicon and manganese.

(Changed edition, Rev. No. 3).

2.5. Reinforcing steel of classes A-I (A240), A-II (A300), A-III (A400), A-IV (A600) is produced by hot-rolled, class AV (A800) - 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 of classes A-V (A800) and A-VI (A1000), provided that a relative elongation of at least 9% and a uniform elongation of at least 2% are obtained 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 sT	Tensile strength sin	Relative extension d5, %	uniform elongation dr, %	Impact strength at -60 °C	Bending and cold test ( from- shipping 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
							45°; from = 5d
							45°; from = 5d

Notes:

1. By agreement between the manufacturer and the consumer, it is allowed not to test the impact strength of reinforcing steel of class As-II (Ac300).

2. (Deleted, Rev. No. 3).

3. For reinforcing steel of class A-IV (A600) with a diameter of 18 mm of steel grade 80C, the bending norm 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 over 20 mm from = 4d.

5. In brackets are indicated conventions fluidity limit.

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

For steel of class A-II (A300) with a diameter of more than 40 mm, a decrease in relative elongation by 0.25% is allowed for each millimeter of diameter increase, 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 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 at least 20%.

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

Table 9

Reinforcing class	Profile number	S
For sT (s 0,2 )	For sin	For sT (s 0,2 )	For sin	For sT (s 0,2 )	For sin	For sT (s 0,2 )	For sin
MPa (kgf / mm 2)	MPa (kgf / mm 2)

Notes:

1. S- standard deviation in the general population of tests;

Sabout- standard deviation in the party-smelting;

Average value in the general population of trials;

Minimum average value in a 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 Sabout by 4.9 MPa (0.5 kgf / mm 2).

3. (Deleted, Rev. No. 5).

The probability of providing the mechanical properties indicated in Table. 8 must be at least 0.95.

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

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 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.

(Changed edition, Rev. No. 2).

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

2.10. Carbon equivalent for welded bar fittings made of low-alloy steel of class A-III (A400) should be no more than 0.62.

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 batch weight should 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;

minimum mean and standard deviations Sabout in the batch of quantities sT (s 0,2 )And sin;

cold bending test results;

values of uniform elongation for steel grades A-IV (A600), A-V (A800), 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;

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

(Changed 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.

(Changed 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.

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

4.4. From each selected rod for tensile, bending and impact testing, one sample is cut off.

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 by applying a bending force from the side of the cut.

4.8. Determination of impact strength is carried out according to GOST 9454-78 on samples with a type U type 3 concentrator 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 for monitoring the mechanical properties and mass of profiles.

4.10. The curvature of the rods is measured along 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, Amendment No. 4).

5. PACKAGING, MARKING, TRANSPORT AND STORAGE

5.1. Packing, marking, transportation and storage - according to GOST 7500-81 with additions:

the ends of the rods from low-alloy steels of class A-IV (A600) must be painted red, class A-V (A800) - 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;

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 the label attached to each bundle 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.

On ligaments, the paint is applied in strips 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 coils in strips with a width of at least 20 mm across the coils on the outside of the coil.

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

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

2. Quality control of indicators of mechanical properties of products at the manufacturer.

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

2.2. Values , , S And Sabout are established 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 quality document for products of the highest quality category, may not conduct tests of mechanical properties.

xmin ³ i - 1,64So

in ³ i ³ ibr,

where in- the average value of mechanical properties according to the results of tests of six samples;

tmin- the minimum value of the test results of six samples.

3.3. Minimum elongation values d 5 and uniform elongation dr must be at least the values given in Table. 8.

(Changed edition, Rev. No. 3).

APPENDIX 2
Mandatory

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

This method 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 to assess the reliability of mechanical properties in each batch-melting and steel as a whole, to control the stability of the technological process.

1. To determine the statistical indicators of mechanical properties (yield strength of physical sT or conditional s 0,2 , tensile strength sin) control test results starting with populations are used.

2. Compliance of the mechanical properties of rolled products with the requirements of normative 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 drawn from the sample refer to the entire population.

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

The sample includes the results of acceptance tests of rolled products of one class, one brand and smelting method, rolled to one or a group 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 the technological process does not change. If necessary, the time period for the sample 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 batch-smelting must be observed. An assessment of the abnormality of the test results is carried out according to the normative and technical documentation.

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

Values , S are determined according to the normative and technical documentation.

8. Checking the stability of characteristics and S carried out in accordance with OST 14-34-78.

9. Size So 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 Sv respectively, the average value and standard deviation of the range distribution for two tests from the lot. Minimum value Sabout equals 1.

10. Determining the value Sabout the experimental method is carried out in at least two heats for each steel grade, class and size profile of rolled products by random selection of at least 100 samples from each heat.

11. The value of the minimum average value of strength characteristics sT (s 0,2 ),sin) in each batch-melt 2 determined from the condition i = - t × S 1 ,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 xmin, determined by the formula

xmin ³ i - 1,64So.

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

i ³ x ibr + 1,64S;

i ³ x ibr;

i³0.9 x ibr + 3So,

where x ibr- rejection value sT (s 0,2 ) And sin specified in the relevant regulatory and technical documentation.

(Introduced additionally, Rev. No. 3).

1. Classification and assortment .. 1

2. Technical requirements. 6

3. Acceptance rules. nine

4. Test methods. 10

5. Packing, marking, transportation and storage. 10

Attachment 1 mandatory Requirements to statistical indicators of mechanical properties. eleven

Annex 2 mandatory Method for determining the statistical indicators of the strength characteristics of the mechanical properties of hot-rolled steel for reinforcing reinforced concrete structures. 12

INFORMATION DATA

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

DEVELOPERS

N. M. Vorontsov, cand. tech. sciences; I. S. Grin, cand. tech. sciences; K. F. Peretyatko; G. I. Snimshchikova; L.G. Bolshikh, E. D. Gavrilenko; cand. tech. sciences; K. V. Mikhailov, Dr. tech. sciences; S. A. Madatyan, cand. tech. sciences; N. M. Mulin, Ph.D. tech. sciences; V. Z. Meshkov, cand. tech. sciences; B. P. Goryachev, Ph.D. tech. sciences; B. N. Fridlyanov; V. I. Petina

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

3. Instead of GOST 5.1459-72, GOST 5781-75

4. REFERENCE REGULATIONS AND TECHNICAL DOCUMENTS

	Item number

GOST 2590-88
GOST 7564-73
GOST 7565-81
GOST 7566-81
GOST 9454-78
GOST 12004-81
GOST 12344-88
GOST 12348-78
GOST 12350-78
GOST 12352-81
GOST 12355-78
GOST 12356-81
GOST 14019-80
GOST 18895-81
	Annex 2

5. The limitation of validity was removed by decision of the Interstate Council for Standardization, Metrology and Certification (minutes 3-93 dated 17.02.93).

6. REPUBLICATION (December 1993) with Amendments No. 1, 2, 3, 4, 5, approved in February 1984, June 1987, December 1987, October 1989, December 1990 (IUS 5- 84, 11-87, 3-88,1-90, 3-91).

GOST 5781-82

INTERSTATE STANDARD

HOT ROLLED STEEL
FOR REINFORCEMENT
REINFORCED CONCRETE STRUCTURES

TECHNICAL CONDITIONS

Introduction date 01.07.83

This standard applies to hot-rolled round steel of a smooth and periodic profile, intended for the reinforcement of ordinary 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) - periodic profile.

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

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

Reinforcing steel of special purpose class As- II (Ac300) are made with profiles shown on or .

The profile shown on the special purpose is made by agreement between the manufacturer and the consumer. The shape and dimensions of the profiles shown on, , can be specified.

1.9. Dimensions and maximum deviations of the dimensions of reinforcing steel of a periodic profile, manufactured according to, , must correspond to those given in , and by , - given in .

Dimensions, mm

Profile number (nominal diameter d n)

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.

The probability of ensuring the mechanical properties specified in 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.

(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 for welded bar reinforcement made of low-alloy steel of class A-III (A400) should be no more than 0.62.

(Introduced additionally, Rev. No. 5).

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

4. TEST METHODS

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

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

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 specified in , with the application of a bending force from the side of the cut.

4.8. Determination of impact strength is carried out according toGOST 9454on samples with a concentrator of the form 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.

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

Metal fittings are mandatory. 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 a high degree of strength, reliability and durability. It is possible to use reinforcement of this class 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 the specific scope of their application. 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:

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	Cross-sectional area, 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, the 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

Reinforcing steel A3 GOST 5781 82. Hot-rolled steel for reinforcing reinforced concrete structures

1. CLASSIFICATION AND ASSORTMENT

2. TECHNICAL REQUIREMENTS

3. ACCEPTANCE RULES

4. TEST METHODS

5. PACKAGING, LABELING, TRANSPORT AND STORAGE

ATTACHMENT 1 Mandatory

REQUIREMENTS FOR STATISTICAL INDICATORS OF MECHANICAL PROPERTIES

APPENDIX 2Mandatory

1. CLASSIFICATION AND ASSORTMENT

2. TECHNICAL REQUIREMENTS

3. ACCEPTANCE RULES

4. TEST METHODS

5. PACKAGING, MARKING, TRANSPORT AND STORAGE

APPENDIX 2Mandatory

1. CLASSIFICATION AND ASSORTMENT

4. TEST METHODS

5. PACKAGING, LABELING, TRANSPORT AND STORAGE

Types of rods

Other classification

Rebar range

Classes of specialized fittings

Color coding

Main area of ​​use

Profile

Fittings class A3 GOST 5781-82

Rebar (STO ASChM 7-93)

ATTACHMENT 1
Mandatory

APPENDIX 2
Mandatory

APPENDIX 2
Mandatory

Main area of use