Cold-Rolled Ribbed Steel Bar (GB 13788-2000)
Cold-rolled ribbed steel bar, also known as cold-rolled ribbed steel, is mainly based on carbon structural steel, which is based on ordinary carbon structural steel and is cold-formed by cold drawn, cold-rolled and cold heading. In order to improve the processing performance and performance of the product, a small amount of manganese (typically about 0.30-1.50%, current 0.45-0.90%) is added, or offset by ferro, manganese and other elements in addition to carbon and silicon.
Cold-rolled ribbed steel bars are mainly used for reinforced concrete and prestressed structures, mainly based on high-strength carbon structural steel grades. Generally, national standard billets with diameter d ≤ 10mm are used for cold heading and other steel products; rolling bar blank (including hot-rolled ribbed steel) for diameter d ≥ 8mm are used for cold rolling and cold drawing; hot-rolled ribbed steel blank diameter 8mm > d ≥ 4mm are mainly used for cold-rolling bar and cold-drawing straight steel; diameter d < 4mm are mainly Used for cold heading, usually need to be annealed first, the annealing temperature control is above Ac3 temperature.
In 2000, GB/T 13788-2000 cold-rolled ribbed steel bars for reinforced concrete was formally implemented, which replaced the old national standard GB/T 13660-86 cold-rolled ribbed steel bar for reinforced concrete. The chargeable carbon content of cold-rolled ribbed bar steel specified in GB/T 13788-2000 is generally 0.45-0.85%, and Mn is 0.45-0.90%. The main features of GB/T 13788-2000, compared with the old national standards, are as follows:
First, the chemical composition of steel is improved and the performance of cold-drawn material is effectively guaranteed.
The second is that the limit of the dimensional accuracy of cold-worked high-strength low-alloy structural steel after cold-drawing is clearly defined.
Third, the technical requirements and test methods for the performance of cold-rolled ribbed steel for reinforced concrete are added.
Fourth, the cold-rolled ribbed bar steel for reinforced concrete should ensure that there is no damaging anti-rolling band or crack before delivery.
The new national standard GB/T 13788-2000 cold-rolled ribbed steel bar for reinforced concrete has higher performance requirements for cold-rolled ribbed bar steel compared with the old national standard. Its implementation will further reduce the cracking and other defects in cold-rolled ribbed steel bars for reinforced concrete, and ensure that this type of steel has better tensile strength, better cracking performance and higher safety factors. Performance and performance will further guarantee the safe and efficient use of cold-rolled ribbed steel bars in the construction of concrete structures.
