This standard specifies the classification, size, shape, quality and allowable deviation, technical requirements, test methods, inspection rules, packaging, marking and quality certificate of steel wire for prestressed concrete. This standard applies to cold-drawn or stress-relieved plain round, spiral ribbed and notched steel wire for prestressed concrete. Stress-relieved steel wire includes low relaxation and normal relaxation. This standard does not recommend normal relaxation grade steel wire. If you need to order normal relaxation grade steel wire, you should indicate it in the contract or negotiate the supply between the supply and demand parties. GB/T 5223-2002 Steel wire for prestressed concrete GB/T5223-2002 Standard download decompression password: www.bzxz.net

ICS77.140.15
National Standard of the People's Republic of China
GB/T5223—2002
Replaces GB/T5223—1995
Steel wires for the prestressing of concrete(1SO 6934-2:1991,Steel for prestressing of Prestressed concrete--Part 2: Cold-drawn wire, NEQ)
Issued on April 9, 2002
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
Implementation on October 1, 2002
GB/T5223--2002
This standard is a revised version of GB/T5223-1995 and corresponds to ISO6934-2:1991 "Steel for prestressed concrete Part 2: Cold-drawn wire". This standard is not equivalent to ISO6934 Part 2, and the main differences are as follows: - Added spiral ribbed steel wire;
- Added strength level;
- Added elongation after fracture instead of total elongation under maximum force as the indicator requirement for daily inspection; - Improved the yield strength ratio of low relaxation steel wire;
Referenced to ASTMA648 standard, added performance requirements for cold-drawn steel wire used as pressure pipe. This standard replaces GB/T5223-1995. Compared with GB/T5223-1995, the main changes are as follows: increased varieties and specifications;
increased strength levels;
increased coil weight requirements;
increased wire strength homogeneity requirements;
the post-fracture length ratio adopts a long gauge length of Lo=200mm; the two-sided notched wire is cancelled;
improved the strength ratio of low relaxation wire;
- increased the performance requirements for cold-drawn steel wire used as pressure pipes; added the fatigue performance test appendix.
Appendix A of this standard is a normative appendix.
This standard was proposed by the former State Metallurgical Industry Bureau. This standard is under the jurisdiction of the National Steel Standardization Technical Committee. The drafting units of this standard are: Tianjin No. 1 Prestressed Steel Wire Co., Ltd., Tianjin Yinlong Prestressed Steel Wire Co., Ltd., Metallurgical Construction Research Institute, Railway Professional Design Institute of the Ministry of Railways, and Metallurgical Industry Information Standard Research Institute. The main drafters of this standard are Zhang Xiufeng, Mao Aiju, Yu Jingqi, Xie Tieqiao, Feng Wenhua, Zhang Nairong and Pan Jie. This standard was first issued in 1985 and revised for the first time in 1995. 1 Scope
Steel wire for prestressed concrete
GB/T5223—2002
This standard specifies the classification, size, shape, quality and allowable deviation, technical requirements, test methods, inspection rules, packaging, marking and quality certificate of steel wire for prestressed concrete. This standard is applicable to plain round, spiral ribbed and notched steel wire for cold drawing or stress relief for prestressed concrete. Stress relief steel wire includes low relaxation and ordinary relaxation. This standard does not recommend ordinary relaxation grade steel wire. If it is necessary to order ordinary relaxation grade steel wire, it should be indicated in the contract or the supply should be negotiated by the supply and demand parties.
2 Normative reference documents
The clauses in the following documents become the clauses of this standard through reference in this standard. For dated references, all subsequent amendments (excluding errata) or revisions are not applicable to this standard. However, parties to agreements based on this standard are encouraged to study whether the latest versions of these documents can be used. For undated references, the latest versions apply to this standard. GB/T228 Metal tensile test methods
GB/T238 Metal wire repeated bending test methods GB/T239
Metal wire torsion test methods
General provisions for acceptance, packaging, marking and quality certification of steel wire GB/T2103
GB/T10120—1996 Metal stress relaxation test methods GB/T17505
General technical requirements for delivery of steel and steel products
YB/T146 Hot rolled wire rod for prestressed steel wire and steel strand YB/T170 Non-alloy steel wire rod for wire making
3 Terms and definitions
The following terms and definitions apply to this standard. 3.1
colddrawwire
colddrawnwire
wire produced by cold working of wire rod through wire drawing die or roller and supplied in coils. 3.2
stress-relievedwiresteelwire produced by one of the following one-time continuous treatment methods. (1) Short-term heat treatment of steel wire under plastic deformation (axial strain) should produce low-relaxation steel wire. (2) Short-term heat treatment of steel wire at appropriate temperature after straightening process should produce normal relaxation steel wire. 3.3
relaxation
The phenomenon of stress reduction with time at a constant length. 3.4
helicalribwirehelicalribwire
The surface of the steel wire has regularly spaced ribs along the length direction (Figure 1). GB/T5223—2002
Indented wire
The surface of the wire has regular indentations along the length direction (Figure 2). B
Schematic diagram of the appearance of spiral ribbed wire
Outer diameter
Figure 2 Schematic diagram of the appearance of three-sided notched wire
4 Classification, code and marking
4.1 Classification and code
4.1.1 Steel wire is divided into two categories according to the processing state: cold-drawn steel wire and stress-relieved steel wire. Stress-relieved steel wire is divided into low-relaxation grade steel wire and ordinary relaxation grade steel wire according to its relaxation performance, and its codes are: cold-drawn steel wire
low-relaxation steel wire
ordinary relaxation steel wire
4.1.2 Steel wire is divided into three types according to its appearance: smooth round steel wire
spiral rib steel wire
notched steel wire
4.2 Marking
4.2.1 Marking content
The marking of products delivered according to this standard shall include the following contents: prestressed steel wire;
nominal diameter;
tensile strength grade;
processing state code;
appearance code;
standard number.
4.2.2 Marking examples
Example 1: The diameter is 4.00mm, the tensile strength is 1670MPa, and the cold-drawn round steel wire is marked as: 2
Prestressed steel wire 4.00-1670-WCD-P-GB/T5223-2002GB/T5223—2002
Example 2: The diameter is 7.00mm, the tensile strength is 1570MPa, and the low relaxation spiral rib steel wire is marked as: Prestressed steel wire 7.0 0-1570-WLR-H-GB/T5223—20025 Order Contents
The contract for ordering according to this standard shall include the following main contents: a) Product name:
b) Overall dimensions;
c) Strength level;
d) Relaxation level;
e) Number of this standard;
f) Processing status;
g) Quantity;
h) Purpose;
i) Other requirements proposed by the purchaser.
6 Dimensions, appearance, quality and allowable deviation
6.1 The dimensions and allowable deviations of round steel wire shall comply with the provisions of Table 1. Refer to Table 1 for the mass per meter. When calculating the reference mass per meter of the steel wire, the density of the steel is 7.85g/cm2.
6.2 The dimensions and allowable deviations of the spiral ribbed steel wire shall comply with the provisions of Table 2. The appearance is shown in Figure 1. The nominal cross-sectional area and reference mass per meter of the steel wire are the same as those of the round steel wire.
Nominal diameter
Dimensions and allowable deviations of the round steel wire, reference mass per meterDiameter allowable deviation/mm
Nominal cross-sectional area
Reference mass per meter/(g/m）
GB/T5223--2002
Nominal diameter
Spiral rib
Quantity/piece
Table 2 Dimensions and allowable deviations of spiral ribbed steel wireBase circle size
Base circle diameter Diameter
Allowable deviation
Outer wheel screen size
Outer wheel profile diameter
Allowable deviation/mm
Single rib size
1.30~1.70
1.60~2.00
1.80~2.20
2.00~2.40
2.50~3.00
Spiral auxiliary lead
6.3 The dimensions and allowable deviations of three-sided notched steel wire shall comply with the provisions of Table 3. The appearance is shown in Figure 2. The cross-sectional area and reference mass per meter of the steel wire are the same as those of the round steel wire. The inclination direction of one of the three notches is opposite to the other two. Table 3 Dimensions and allowable deviations of three-sided notched steel wire Nominal diameter
Notch depth
Nominal depth a/mm
Notch length
a Allowable deviation/mm Nominal pitch L/mm
Allowable deviation/mm Nominal length b/mm
Note: The nominal diameter refers to the diameter corresponding to the cross-sectional area equal to that of the round steel wire. 6.4 Steel wires with specifications other than those in Tables 1, 2 and 3 can be produced according to the requirements of the purchaser. 5.5
Allowable deviation/mm
6.5The out-of-roundness of smooth round and spiral ribbed steel wire shall not exceed 1/2 of its diameter tolerance.6.6 Coil weightEach coil of steel wire consists of one wire, and its coil weight shall not be less than 500kg. It is allowed that 10% of the coils are less than 500kg but not less than 100kg.
6-7 Coil inner diameter:
6.7.1 The coil inner diameter of cold-drawn steel wire shall not be less than 100 times the nominal diameter of the steel wire. 6.7.2 The coil inner diameter of stress-relieved steel wire shall not be less than 1700mm. 7 Technical requirements
7.1 Grade and chemical composition
The grade and chemical composition of steel used to manufacture steel wire shall comply with the provisions of YB/T146 or YB/T170. Other grades may also be used for manufacturing, and the composition is not a delivery condition.
7.2 Manufacturing method
7.2.1 The steel wire shall be manufactured from sorbitized wire rod and then cold drawn or subjected to stress relief treatment after cold drawing. 7.2.2 The finished steel wire shall not have electric welded joints. Electric welded joints welded for continuous operation during production shall be cut off. 7.3 Mechanical properties
7.3.1 The mechanical properties of cold drawn steel wire shall comply with the provisions of Table 4. The value of the specified non-proportional elongation stress cpo.2 shall not be less than 75% of the nominal tensile strength. In addition to the tensile strength and the specified non-proportional elongation stress, the steel wire for pressure pipes shall also be tested for the reduction of area, the number of torsions and the relaxation rate; the steel wire for other purposes shall also be tested for the elongation after fracture and the number of bends. 4
GB/T5223—2002
7.3.2 The mechanical properties of stress-relieved smooth round and spiral ribbed steel wires shall comply with the provisions of Table 5. The non-proportional elongation stress apo. value for low relaxation steel wire shall not be less than 88% of the nominal tensile strength, and for ordinary relaxation steel wire shall not be less than 85% of the nominal tensile strength. 7.3.3 The mechanical properties of the notched steel wire with stress relief shall comply with the provisions of Table 6. The non-proportional elongation stress 0pa.2 value for low relaxation steel wire shall not be less than 88% of the nominal tensile strength, and for ordinary relaxation steel wire shall not be less than 85% of the nominal tensile strength. 7.3.4 For the convenience of daily inspection, the total elongation under the maximum force in Table 4 can be replaced by the post-break elongation of L, = 200mm, but its value shall not be less than 1.5%; the total elongation under the maximum force in Tables 5 and 6 can be replaced by the post-break elongation of L. = 200mm, but its value shall not be less than 3.0%. The arbitration test shall be based on the total elongation under the maximum force. Table 4 Mechanical properties of cold drawn steel wire
Under maximum force
Tensile strength
Nominal diameter
Nominal diameter
oL/MPa
Not less than
Tensile strength
ap/MPa
Not less than
Specified non-proportional
Elongation stress
apa/MPa
Not less than
Total elongation
(Lg=200mm）
Not less than
Number of bendings
(times/180°)
Not less than
Bending radius
Sectional reduction
Not less than|| tt||5 Mechanical properties of stress-relieving smooth round and spiral-assisted steel wire Table 5
Specified non-proportional
Elongation stress under maximum force
apn2/MPa
not less than
WLRWNR
12901250
13801330
12901250
Total elongation
(L.=200mm)
not less than
Number of bending times/
(times/180°)
not less than
Bending radius
The actual strength of each batch of steel wire delivered should not be higher than its nominal strength grade of 200MPa. The number of twists per 210mm
torque
is not less than
when the initial stress is equivalent to
70% of the nominal tensile
strength. The stress relaxation rate
after 1000h
is not greater than
stress relaxation performance
after 1000h, the initial stress is equivalent to
the nominal tensile strength
percentage/%
stress relaxation rate r/%
is not greater than
for all specifications
GB/T5223--2002
nominal diameter
tensile strength||t t||not less than
specified non-proportional
elongation stress
not less than
Table 6, mechanical properties of stress-relieving notched steel wire under maximum force
total elongation
(L.=200mm)
WLRWNR
12901250
14701410
15601500
16401580
12901250
13801330
14701410
15601500
not less than
number of bending times!
(times/180°)
Not less than
Bending radius
7.3.6 The elastic modulus of the steel wire is (205±10)GPa, but it is not a delivery condition. Stress relaxation performance
After 1000h, the initial stress should be
equivalent to
percentage/% of the nominal tensile strength
Stress relaxation rate r/%
Not greater than
For all specifications
7.3.7 According to the supply agreement, steel wires of other strength levels other than those in Table 4, Table 5 and Table 6 can be supplied, and their mechanical properties shall be implemented in accordance with the agreement. 7.3.8 It is allowed to use the extrapolation method to determine the 1000h relaxation value (see 8.7.6). 7.3.9 For steel wires for sleepers, the supplier shall conduct a head strength test. The strength of the head shall not be less than 95% of the nominal tensile strength of the parent material. Other wires that require head fixing shall be specified in the contract and implemented with reference to this clause. 7.4 Surface quality
7.4.1 The surface of the steel wire shall not have cracks and oil stains, nor shall there be any marks or mechanical damage that may affect the use. 7.4.2 Unless otherwise agreed by the supplier and the buyer, as long as there are no visible rust pits on the surface of the steel wire, the surface rust shall not be used as a reason for rejection.
7.4.3 The surface of the stress-relieved steel wire is allowed to have tempering color. 7.5 Straightness of stress-relieved steel wire
Take a steel wire with a chord length of 1m and place it on a plane. The maximum natural sagittal height between the chord and the inner side of the arc shall not exceed 25mm for notched steel wire and 20mm for smooth round and spiral rib steel wire.
7.6 Fatigue test
After negotiation between the supplier and the buyer, the fatigue performance test of the steel wire can be specified in the contract. 8 Test method
8.1 Surface inspection
The surface quality shall be visually inspected.
8.2 Dimension inspection
8.2.1 The diameter of the steel wire shall be measured with a measuring tool with a graduation value of 0.01mm, and measured in two perpendicular directions of the same cross section at any part. 8.2-2 The lead of the spiral ribbed steel wire, the notch length and pitch of the notched steel wire shall be measured along the axial direction of the steel wire, and the rib width of the spiral ribbed steel wire shall be measured in the normal direction of the spiral rib.
8.3 Measurement of mass per meter
The unit mass of steel wire should be measured as follows: Take 3 steel wires with a length of not less than 500mm, measure the length of each steel wire with an accuracy of 1mm, weigh the mass of each steel wire, accurate to 0.1g, and then calculate the unit mass of each steel wire according to formula (1). M=1000×m
Where:
M—single weight of steel wire, in grams/meter (g/m); - weighed mass of steel wire, in grams (g); m
L—-length of steel wire, in millimeters (mm). The measured unit mass is the average of the three calculated values. 8.4 Tensile test
8.4.1 Tensile strength
GB/T5223—2002
The tensile test of steel wire shall be carried out in accordance with the provisions of GB/T228. The nominal cross-sectional area value of the steel wire shall be taken when calculating the tensile strength. 8.4.2 Specified non-proportional elongation stress
The determination of the specified non-proportional elongation stress shall be carried out in accordance with the provisions of GB/T228. In order to facilitate the supplier's daily inspection, the specified non-proportional elongation stress po.2 of the steel wire can also be replaced by the stress at the specified total elongation of 1%. If its value meets the provisions of this standard, it can be delivered, but 0po.z shall be measured during the arbitration test. The preload during measurement is 10% of the nominal non-proportional elongation load. 8.4.3 Total elongation under maximum force
The determination of total elongation under maximum force shall be carried out in accordance with the provisions of GB/T228. When using a computer to collect data or an electronic tensile device, the elongation caused by the preload on the specimen should be added to the total elongation when measuring the elongation, and the measured elongation should be rounded to approximately 0.5%. 8.4.4 Elongation after fracture
The determination of elongation after fracture shall be carried out in accordance with the provisions of GB/T228. During routine inspection, the gauge scratch of the specimen shall not cause the fracture to occur at the scratch. The specimen length shall ensure that the distance between the upper and lower jaws of the testing machine exceeds the original gauge length by more than 50mm. The minimum scale of the measuring tool for measuring the gauge length after fracture shall not be greater than 0.1mm. The measured elongation should be rounded to approximately 0.5%. 8.4.5 Sectional reduction
The determination of sectional reduction shall be carried out in accordance with the provisions of GB/T228. After the steel wire is broken, its diameter is measured in two mutually perpendicular directions at the minimum necking point (if necessary, the broken parts of the specimen should be butt-jointed at the fracture point) and the average value d is taken. The outer contour of the spiral ribbed steel wire is measured. The area reduction ratio is calculated according to formula (2):
electric-1-
Where:
——area reduction ratio;
d is the average diameter after fracture, in millimeters (mm); d is the original average diameter, in millimeters (mm). ×100%
8.4.6 If the specimen breaks in the chuck or 2d away from the jaws and the performance does not meet the requirements of this standard, the test is invalid. 8.5 Bending test
(2)
The bending test of steel wire shall be carried out in accordance with the provisions of GB/T238. The bending radius shall comply with the corresponding provisions of Table 4, Table 5 and Table 6 of this standard. 8.6 Torsion test
8.6.1 The torsion test shall be carried out in accordance with the provisions of GB/T239. 8.6.2 During the test, the distance between the clamps of the testing machine shall not be less than 210mm. 8.6.3 The torsion rate used shall not exceed 30r/min. 8.6.4 The axial tension is 0.5%2% of the load corresponding to the nominal tensile strength of the steel wire. 8.6.5 The specimen shall be twisted until it is completely broken, and at least 3/4 of the area of ​​the broken section is perpendicular to the axis of the steel wire. The number of twists shall meet the requirements of Table 4.
8.6.6 If there are spiral cracks on the surface of the specimen that can be seen visually or touched by bare hands after twisting, the coil of steel wire shall be retested according to 8.6.7. 8.6.7 Retest of torsion cracks
The retest specimen shall be twisted at a ratio of 3 turns per 210mm length. When the specified number of turns is reached, the machine shall be stopped for inspection. If there are still spiral cracks that can be seen visually or touched by bare hands, the coil of steel wire shall be judged as unqualified. 7
GB/T5223—2002
8.6.8 If the specimen breaks within 2d. from the chuck and the number of twists specified in this standard is not reached, the test shall be invalid. 8.7 Stress relaxation performance test
8.7.1 The stress relaxation performance test of steel wire shall be carried out in accordance with the provisions of GB/T10120. 8.7.2 The ambient temperature of the sample during the test shall be maintained within the range of 20°C ± 2°C. 8.7.3 The gauge length of the sample shall not be less than 60 times the nominal diameter. 8.7.4 No heat treatment or cold processing shall be performed after the sample is prepared. 8.7.5 The initial load shall be evenly applied within 3min to 5min, and the relaxation value shall be recorded after holding the load for 1min. 8.7.6 It is allowed to use test data of not less than 100h to calculate the relaxation value of 1000h. 8.8 Head strength test
The head diameter of the steel wire shall not be less than 1.5 times the nominal diameter of the steel wire. The tensile test is carried out with an anchor. At this time, the ratio of the maximum force of the steel wire to the nominal cross-sectional area of ​​the steel wire is the head strength. 8.9 Fatigue test
The fatigue performance test shall be carried out in accordance with Appendix A.
9 Inspection rules
The inspection rules for steel wire shall comply with the provisions of GB/T2103 and GB/T17505. 9.1 Inspection and acceptance
The factory inspection of steel wire shall be carried out by the supplier's technical supervision department in accordance with Table 7, and the purchaser may conduct inspection and acceptance in accordance with this standard. 9.2 Batch rules
Steel wire shall be inspected and accepted in batches. Each batch of steel wire shall consist of steel wires of the same brand, specification and processing status, and the mass of each batch shall not exceed 60t.
9.3 Inspection items and sampling quantity
9.3.1The inspection items of different types of steel wire shall be carried out in accordance with the corresponding provisions of Table 4, Table 5 and Table 6, and the sampling quantity shall comply with the provisions of Table 7. 9.3.21000h stress relaxation test and fatigue performance test shall only be carried out for type inspection, that is, when there are major changes in raw materials, production processes and equipment, new products shall be put into production and production shall be resumed after suspension. Table 7 Supplier's routine inspection items and sampling quantity before delivery Sequence
Inspection items
Overall dimensions
Stress relief wire straightness
Tensile strength
Specified non-proportional elongation stress
Total elongation under maximum force
Elongation after fracture
Sectional reduction
Forging head strength
Stress relaxation performance
Sampling quantity
1 piece/reel
1 piece/reel
3 pieces/batchbZxz.net
3 pieces/batch
1 piece/reel
1 piece/reel
1 piece/reel
3 pieces/batch
Not less than 1 piece/each containing the same batch
Sampling location
In each (any) plate
Take at any end
Test method
According to 8.2 of this standard
Measure with a measuring tool with a graduation value of 1mm
According to 8.4.1 of this standard
According to 8.4.2 of this standard
According to 8.4.3 of this standard
According to 8.4.4 of this standard
According to 8.5 of this standard
According to 8.6 of this standard
According to 8.4.5 of this standard
According to 8.8 of this standard
According to 8.7 of this standard
Note: *Contract batch is the total amount of an order contract. In special cases, the relaxation test can be replaced by the factory's continuous inspection to provide data of the same raw material and the same production process.
9.4 Re-inspection and determination rules
The re-inspection and determination rules for steel wire shall be implemented in accordance with the provisions of GB/T2103. 10 Packaging, marking and quality certificate
The general requirements for the packaging, marking and quality certificate of steel wire shall be implemented in accordance with the provisions of GB/T2103. 10.1 Packaging
GB/T5223—2002
Steel wire is generally packaged according to Class I in GB/T2103. Special requirements should be indicated in the contract and can be packaged according to Class 1 and Class Ic. 10.2 Marking
Steel wire should be labeled for each coil, on which the supplier's name, trademark, specification, strength level, implementation standard number, etc. shall be indicated. 10.3 Quality Certificate
Each contract batch shall be accompanied by a quality certificate, which shall indicate: supplier name, address and trademark, specifications, strength level, purchaser name, contract number, quality, product mark, implementation standard, number, factory date, and technical supervision department stamp. GB/T5223—2002
Appendix A
(Normative Appendix)
Fatigue Test
A.1 The specimen used for fatigue test shall be directly cut from the finished steel wire, and the specimen length shall ensure that the distance between the two clamps is not less than 140mm
A.2 The steel wire shall be able to withstand 2×10 times of 0.7F～(0.7F.—2△F.) pulsating load without breaking. Round steel wire: 2△AF./S, 200MPa
Spiral ribbed and notched steel wire: 2△F./S 180MPa Where:
Fb——nominal breaking force of steel wire, in Newton (N); 2△F. -Equivalent load value of a stress range (twice the stress amplitude), in Newton (N); S. Nominal cross-sectional area of ​​steel wire, in square millimeters (mm). A.3 The static measurement accuracy of the maximum stress of pulsating stretching to maintain constant stress during the entire test should reach ±1%. A.4 The stress cycle frequency cannot exceed 120Hz. A.5 All stresses are transmitted to the specimen axially, without the influence of jaws and notches, and any slippage of the specimen in the chuck shall be limited by a corresponding device table.
A.6 The test is invalid if the specimen breaks in the chuck or in the clamping area (2 times the nominal diameter of the steel wire) due to notch influence or local overheating. A.7 During the test, the temperature of the specimen shall not exceed 40°C, and the ambient temperature of the test room shall be within the range of 18°C ​​to 25°C. 10
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