GOST 5781-82

INTERSTATE STANDARD

HOT ROLLED STEEL
FOR REINFORCEMENT
REINFORCED CONCRETE STRUCTURES

TECHNICAL CONDITIONS

Introduction date 01.07.83

This International Standard applies to hot-rolled smooth and shaped round steel 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-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, grades 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).

1.3. Profile numbers, areas cross section, weight 1 m length reinforcing steel smooth and periodic profile, as well as the maximum mass deviations for periodic profiles must comply with those specified in.

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

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.

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. 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).

Mass fraction aluminum manufacturer determines 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.

4.2. 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.

4.6. 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

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 concrete structures (reinforcing steel).
In terms of norms chemical composition 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 size in terms of cross-sectional area.

Table 1

(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) with a 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-IV (A600), A-V (A800), A-VI (A 1000) with the 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.

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

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 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 a rod of class A-IV (A600), steel grades are set by agreement between the manufacturer and the consumer.

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.

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 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. eight.
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. 9.
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).

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).

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).

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 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

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 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 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) or the class symbol for the yield strength (A400) is applied.

Hot-rolled round steel of a smooth and periodic profile, intended for reinforcing ordinary and prestressed reinforced concrete structures (reinforcing steel), is produced in accordance with GOST 5781-82.

CLASSIFICATION AND RANGE

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).

Reinforcing steel is produced in rods or coils. Reinforcing steel is produced:

• class A-l(A240) - smooth profile;
• other classes - periodic profile.

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

Table 1. Numbers of profiles, cross-sectional areas, weight of 1 m length of reinforcing steel of a smooth and periodic profile (GOST 5781-82)

Notes.

The mass of 1 m of the profile is calculated from nominal dimensions with a steel density of 7.85 g/cm3.

The probability of providing a mass of 1 m must be at least 0.9.

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

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

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.

Reinforcing steel of class A-II (A300), made in the usual version, with a profile shown in fig. 1a, and the special purpose Ac-II (Ac300) with the 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. 1 b, and classes A-IV (A600), A-V (A800), A-VI (A1000) with the profile shown in fig. 1 b, 2 b, should have protrusions along helical lines, having on one side of the profile the right one, and on the other - the left one.

Reinforcing steel for special purposes of class Ac-II (Ac300) is made with the profiles shown in fig. 1a or 2a. The profile shown in fig. 2a, a special purpose is manufactured by agreement between the manufacturer and the consumer. The shape and dimensions of the profiles shown in fig. 2a and 2b can be refined.

Table 2. The dimensions of the reinforcing steel shown in fig. 1 a, b (GOST 5781-82)

Reinforcing steel of classes A-l (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 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 are made in rods, with a diameter of 6 and 8 mm, they are made by agreement between the manufacturer and the consumer in coils.

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.

Table 3 The dimensions of the reinforcing steel shown in fig. 2 a, b (GOST 5781-82)

Table 4 Grades of low-alloy and carbon steel used for the manufacture of fittings (GOST 5781-82)

Notes.

It is allowed to manufacture reinforcing steel of class A-V (A800) from steel grades 22Kh2G2AYU, 22Kh2G2R and 20Kh2G2SR.

The dimensions indicated in brackets are made by agreement between the manufacturer and the consumer.

Reinforcing steel of classes Al (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 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.

SYMBOL 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-l (A240):

18-A-I GOST 5781-82

Note.

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

This standard applies to hot-rolled smooth and ribbed reinforcing steel intended for the reinforcement of conventional and prestressed concrete structures.

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

GOST 10884-81

Thermomechanical and thermally hardened steel rods of a periodic profile with a diameter of 6-40 mm (building fittings) are intended for the construction of critical reinforced concrete structures.
According to this standard building fittings depending on the mechanical properties, they are divided into classes: Ax-III, At-IV, At-V, At-VI, At-VII, At-VIII.
Reinforcement according to this standard is made from steel of the following grades:

GOST 5781-82

Depending on the mechanical properties, the reinforcement is divided into classes A-I (A240), A-II (A300), A-III (A400), A-IV (A600), A-V (A800), A-VI (A1000).
Building reinforcement is made in rods or coils. Construction fittings class A-I (A240) is made smooth, classes A-II (A300), A-III (A400), A-IV (A600), A-V (A800), A-VI (A1000) - a periodic profile. At the request of the consumer, fittings of classes A-II (A300), A-III (A400), A-IV (A600), A-V (A800) are made smooth.

Construction fittings 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.

Construction fittings class A-II (A300), made in the usual version, and special purpose Ac-II (Ac300), must have protrusions running along helical lines with the same lead on both sides of the profile.

Construction fittings class A-III (A400) and classes A-IV (A600), A-V (A800), A-VI (A1000) must have protrusions along helical lines having right-handed on one side of the profile and left-handed entries on the other.

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

Construction fittings 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 are produced in coils or rods, large diameters - in rods. Construction fittings classes A-IV (A600), A-V (A800) and A-VI (A1000) of all sizes are produced in rods, with a diameter of 6 and 8 mm - by agreement between the manufacturer and the consumer in coils.

Construction fittings it is made of carbon and low-alloy steel grades indicated in the table. For reinforcing bars of class A-IV (A600), steel grades are set by agreement between the manufacturer and the consumer.

Steel grades used for the manufacture of reinforcement of different classes (GOST 5781-82)

Notes:
It is allowed to manufacture fittings of class A-V (A800) from steel grades 22Kh2G2AYU, 22Kh2G2R and 20Kh2G2SR. The dimensions of the reinforcement indicated in brackets are made by agreement between the manufacturer and the consumer.

The West Siberian Metallurgical Plant produces thermomechanically hardened building fittings classes A400C and A500C according to TU 14-1-5254-94. The low carbon content, along with the thermomechanical processing of the reinforcement in the rolled stream, ensures its improved weldability and ductility, increased toughness and durability. This building heat-strengthened reinforcement according to its properties meets the requirements of international standards.

Gosstroy of Russia recommends the use of A400S and A500S reinforcing steel in reinforced concrete structures along with and instead of A-III grade 25G2S and 35GS (GOST 5781-82) and At-IIIS (GOST 10884-81) reinforcing steel of the same diameters. Thermotechnical and thermally hardened steel rods of a periodic profile with a diameter of 6-40 mm are intended for the construction of critical reinforced concrete structures (GOST 10884-81).
Bar reinforcement parameters (GOST 5781-82)

Armature thermomechanically strengthened for reinforced concrete structures. GOST 10884-94

Thermal fittings are divided into classes depending on:

• from the mechanical properties - the strength class of the reinforcement (established by the standard of the normalized value of the conditional or physical yield strength in newtons per square millimeter);
• from operational characteristics - to welded reinforcement (index C), reinforcement resistant to corrosion cracking (index K).

Fittings are manufactured in classes At400S, At500S, At600, At600S, At600K, At800, At800K, At1000, At1000K and At1200. By agreement between the manufacturer and the consumer, reinforcement of strength class At800 and above is allowed to be made smooth.

Marking:

In the absence of rolling marking, the ends of the rods or bundles of reinforcement of the corresponding class must be painted with indelible paint of the following colors:

• Fittings At400S - white;
• Fittings At500S - white and blue;
• Fittings At600 - yellow;
• Fittings At600S - yellow and white;
• Fittings At600K - yellow and red;
• Fittings At800 - green;
• Fittings At800K - green and red;
• Fittings At1000 - blue;
• Fittings At1000K - blue and red;
• Fittings At1200 - black.

Steel rod fittings and wire rod belong to the category long products. Rebar and wire rod are manufactured according to the following specifications:

According to the nature of the profile, the reinforcement is divided into smooth - class AI and corrugated (periodic profile for reinforcement) - class AII, AIII, AIV, AV, AVI.

The assortment of reinforcement and wire rod corresponds to:

The chemical composition of steel grades used for the manufacture of fittings and wire rod corresponds to:

• Fittings - depending on the class:

1. Armature AI - St3kp(ps, cn);
2. Armature AII - St5sp(ps), 18G2S;
3. Armature III - 35GS, 25G2S, A500S, A400S, 32G2RPS.