GB 1499.2-2024Steel for the reinforcement of concrete - Part 2: Hot rolled ribbed bars (English PDF)

5.4 Delivery type and allowable deviation

5.4.1 Steel bars shall be delivered in fixed length according to straight bars. The delivery length shall be specified. The allowable deviation for length is.

5.4.2 Steel bars with a diameter not exceeding 16 mm are allowed to be delivered in coils. Cut the head and tail when delivering. Each coil shall consist of one steel bar. Each batch is allowed to have 5% of the number of coils (two coils are allowed if there are less than two coils) composed of two steel bars. The weight of the inventory shall be determined through negotiation between the supplier and the purchaser.

5.6 Weight and allowable deviation

5.6.1 Steel bars shall be delivered by weight. There are two delivery methods. in actual weight and theoretical weight. The theoretical weight of steel bars is calculated by multiplying the length of the steel bars by the theoretical weight per meter of steel bars in Table 2.

5.6.2 The allowable deviation between the actual weight and theoretical weight of steel bars shall comply with the provisions of Table 4.

6.3 Mechanical properties

6.3.1 The mechanical property characteristic values of steel bars, such as lower yield strength ReL, tensile strength Rm, elongation at break A, and maximum total elongation at break Agt, shall comply with the provisions of Table

6.For the mechanical performance characteristic values listed in Table 6, R°eL/ReL is the maximum guaranteed value and others are the minimum guaranteed values.

6.3.2 The elongation at break A of various designations of steel bars with nominal diameters ranging from 28 mm~40 mm is allowed to be reduced by 1%. The elongation at break A of each designation of steel bars with a nominal diameter greater than 40 mm is allowed to be reduced by 2%.

6.4 Process performance

6.5 Fatigue performance When applied to concrete structures or components that bear dynamic cyclic effects such as highway bridges and culverts, railway bridges and culverts, and underground structures of urban rail transit, corresponding fatigue performance test reports of corresponding designations and specifications shall be provided. Fatigue performance testing shall be conducted in accordance with GB/T 28900, with 5 steel bars cut from different pieces (coils).

6.6 Connection performance

6.6.1 The welding and mechanical connection process of steel bars, as well as the quality inspection and acceptance of joints, shall comply with the provisions of JGJ 18 and JGJ 107.

6.6.2 The welding process for HRBF500 and HRBF500E steel bars shall be determined through testing.

6.6.3 HRB600 steel bars are mechanically connected. Welding is allowed for connection.

6.7 Grain size

6.8 Microstructure The metallographic structure of steel bars shall mainly consist of ferrite and pearlite. There shall be no tempered martensite structure on the core. The macroscopic metallography, cross-sectional Vickers hardness, and microstructure of steel bars shall comply with the provisions of Annex B. After consultation between the supplier and the purchaser, it is allowed not to conduct metallographic examination.

7.2 Tensile, bending, and reverse bending tests

7.2.1 Tensile, bending, and reverse bending test specimens shall not be machined.

7.2.2 The cross-sectional area used to calculate the strength of steel bars is the nominal cross-sectional area listed in Table 2.

7.2.3 Reverse bending test. First bend the specimen in the forward direction by 90°, and keep it at a temperature of 100°C± 10°C for no less than 30 min after the forward bending. After natural cooling, bend it in the opposite direction by 20°. Both bending angles shall be measured while maintaining the load. Exit-factory inspection allows direct reverse bending at room temperature. Arbitration inspection shall be carried out by reverse bending after the time limit.

7.3 Size measurement

7.3.1 The measurement of the inner diameter of steel bars shall be accurate to

0.1 mm.

7.3.2 The measurement of the height of longitudinal and transverse ribs of steel bars adopts the method of measuring the average height of the center of the transverse ribs on both sides of the same section. That is, measure the maximum outer diameter of the steel bar, subtract the inner diameter at that location, and obtain half of the value as the rib height at that location, which shall be accurate to

0.1 mm.

7.3.3 The spacing between the transverse ribs of the steel bars is measured using the method of measuring the average rib spacing. That is, measure the center distance between the 1st and 11th transverse ribs on the same side of the steel bar. The value divided by 10 is the spacing between the transverse ribs, which shall be accurate to

0.1 mm.

7.3.4 Measure the chord length between the two ends of adjacent transverse ribs projected perpendicular to the axis plane of the steel bar by measuring the gap between the ends of the transverse ribs of the steel bar. The schematic diagram of measuring the gap at the end of the steel bar transverse rib is shown in Figure 2. Keys.

7.4 Measurement of weight deviation

7.4.1 When measuring the weight deviation of steel bars, specimens shall be taken from different steel bars. The quantity is 5 pieces. The length of each specimen shall not be less than 500 mm. The length shall be measured one by one, with an accuracy of 1 mm. When measuring the total weight of the specimen, it shall be accurate to 1 g.

7.4.2 The deviation (%) between the actual weight and theoretical weight of the steel bar shall be calculated according to formula (2).

7.5 Macroscopic metallography, cross-sectional Vickers hardness, microstructure inspection The inspection of macroscopic metallography, cross-sectional Vickers hardness, and microstructure shall be carried out in accordance with the provisions of Annex B. Microstructure shall be used as the basis for arbitration.

7.6 Numerical rounding and judgment The rounding and judgment of the test results shall comply with the provisions of YB/T 081.

8.2 Characteristic value inspection

8.2.1 Characteristic value inspection is applicable to the following situations.

a) Supplier's inspection of product quality control;

b) Inspection required by the purchaser and after mutual agreement between the supplier and the purchaser;

c) Third party product certification and arbitration inspection.

8.2.2 The characteristic value inspection shall be conducted in accordance with the provisions of Annex C.

8.3 Delivery inspection

8.3.1 Applicable situation Delivery inspection is applicable to the inspection of steel bar acceptance batches.

8.3.2 Batching rules

8.3.3 Inspection items and sampling quantity When the weight of each batch is not more than 60 t, samples shall be taken and inspected according to the requirements in Table

8.When the weight of each batch is greater than 60 t, for every additional 40 t (or the remainder of less than 40 t), 1 tensile test specimen and 1 bending test specimen shall be added. An additional reverse bending test specimen shall be added for steel bars of designations with "E".

8.3.4 Inspection results The inspection results of each inspection item of steel bars (including steel bars straightened by coiling) shall comply with the relevant provisions of Chapter 5 and Chapter 6.

8.3.5 Re-inspection and judgement The re-inspection and judgment of steel bars shall comply with the provisions of GB/T 17505.The weight deviation of steel bars shall not be resampled for re-inspection.