1. Rebar and steel wire

The steel bars used in the structure are often divided into hot-rolled steel bars and cold-worked steel bars according to different processing methods.

(1) Hot rolled steel bars. The finished steel bar that has been hot-rolled and cooled in vain is called hot-rolled steel bar.

(2) Cold drawn steel bars. The hot-rolled steel bar is fixed at one end at room temperature, and the other end is stretched, so that the stress exceeds the yield point until plastic deformation occurs. This method is called cold-drawn processing. The yield point of the steel bar after cold drawing can be increased by 20%-30%. For example, the yield point and tensile strength of the steel bar after aging treatment (that is, natural weight release after cold drawing for 15-20 days or heating to 100-200℃, heat preservation for a period of time) Improved, but plasticity and toughness are correspondingly reduced.

(3) Cold drawn low carbon steel wire. A steel wire made of Q235 (or Q215) hot-rolled round wire rod with a diameter of 6.5-8mm through a wire-drawing machine for multiple strong cold-drawing processes.

2. Section steel

Steel ingots with various cross-sections made by hot rolling are called section steels (or sections). There are round steel, square steel, flat steel, hexagonal steel, angle steel, Gongning steel, channel steel, steel pipe and steel plate. Sectional steel belongs to the steel structure for steel structure. Sectional steels with different cross-sections can be made into various steel components as required. There are two main types of section steels according to their chemical composition: carbon structural sodium and low-alloy structural steel.

3. Cold rolled steel bar

Steel cold-rolled ribbed steel bars: cold-rolled ribbed steel bars are made of ordinary low-carbon steel or low-alloy steel hot-rolled round wire rod as the base material. After cold-rolled or cold-drawn, the surface is cold-rolled to have three sides or two sides. Steel bars with crescent-shaped cross ribs.

The cold-rolled auxiliary steel bars in reinforced concrete structures and prestressed concrete structures can be selected according to the following regulations:

Grade 550 steel bars should be used as the main force-bearing reinforcement, erection reinforcement, stirrup and structural reinforcement in reinforced concrete structural members. Grade 650 and 800 steel bars should be used as the main force-bearing reinforcement in prestressed concrete structural members. In addition, the concrete strength grade of reinforced concrete structures using cold-rolled ribbed steel bars should not be lower than C20; the concrete strength grade of prestressed concrete structural members should not be lower than C30.

Note: For structural members in indoor high humidity or open air environment, the concrete strength grade shall not be lower than c30.