What is the difference between rebar and rebar?

1. Different shapes. The outer surface of round steel is smooth; The outer surface of the steel bar has spiral ribs. ?

2. Different production standards. In the current standard, round steel refers to HPB235 grade steel bar, and its production standard is Hot Rolled Smooth Steel Bar for Reinforced Concrete (GB13013); +03); Rebar generally refers to HRB335 and HRB400 grade steel bars, and its production standard is Hot Rolled Ribbed Steel Bar for Reinforced Concrete (GB 1499). ?

3. The strength is different. The design strength of round steel (HPB235) is 210 MPa; ; The strength of rebar is higher than that of round steel, and the design strength of HRB335 is 300MPa. The design strength of HRB400 is 360MPa. ?

4. Different steel grades (different chemical compositions). Round steel (HPB235) belongs to carbon steel, and the steel grade is Q235；; The reinforcement is low alloy steel, and the HRB335 grade reinforcement is 20mnsi (20mnsi); HRB400 grade rebar is 20 mnsy or 20MnSiNb or 20MnTi, etc.

Extended data:

1 Precautions for reinforcement:

The quality of finished rebar varies with metallurgical smelting heat and hot rolling batch, and the heat number and batch number are the basis of sampling inspection. Therefore, import and use departments and storage departments should pay attention to keeping the marks on the goods, and export enterprises and foreign trade departments should also distinguish batches and furnace numbers according to the standard requirements and provide quality certificates.

Rebar is usually delivered naked and bundled, so attention should be paid to moistureproof during storage, and corrosion will have a negative impact on the performance of rebar.

2 steel production process:

Rebar is a ribbed steel bar on the surface, also known as ribbed steel bar. It usually has two longitudinal ribs and transverse ribs, which are evenly distributed along the length direction. The shapes of transverse ribs are spiral, herringbone and crescent. Expressed in millimeters of nominal diameter. The nominal diameter of ribbed steel bar is equivalent to the nominal diameter of smooth round steel with equal cross section. The nominal diameter of reinforcement is 8-50mm, and the recommended diameters are 8, 12, 16, 20, 25, 32 and 40 mm..

Ribbed steel bars mainly bear tensile stress in concrete. Ribbed steel bars have great bonding ability with concrete due to the function of ribs, so they can better withstand the action of external forces. Ribbed steel bars are widely used in various building structures, especially large, heavy, light thin-walled and high-rise building structures.

Rebar is produced by small rolling mills, the main types of which are continuous, semi-continuous and horizontal. Most of the newly built and used small tandem mills in the world. The popular steel bar mills are universal high-speed rolling steel bar mill and four-split high-yield steel bar mill.

The billets used in small continuous rolling mills are generally continuous casting billets, with a side length of 130~ 160mm, a length of about 6 ~ 12m and a unit weight of 1.5~3 tons. Most of the rolling lines are criss-crossed, realizing full-line torsion-free rolling. According to different blank specifications and finished product sizes, there are 18, 20, 22 and 24 small rolling mills, and 18 is the mainstream.

Bar rolling mostly adopts new technologies such as walking beam heating furnace, high pressure water descaling, low temperature rolling and endless rolling. Rough rolling and intermediate rolling are developing in the direction of adapting to large billet and improving rolling accuracy, while finishing mill mainly improves accuracy and speed (reaching 18m/s). The product specifications are generally Ф10-40mm, but also Ф 6-32mm or Ф12-50mm. The steel grades produced are low, medium and high carbon steel and low alloy steel, which are in great demand in the market; The maximum rolling speed is 18m/s, and the production process is as follows:

Walking beam heating furnace → roughing mill → middle rolling mill → finishing mill → water cooling device → cold bed → cold shear → automatic counting device → bundling machine → discharging bench The theoretical weight calculation formula of reinforcement provided by Shanghai Jiuzheng Environmental Protection Building Materials Co., Ltd. is: external diameter х external diameter х0.006 17 = kg/M- size and weight balance manufacturer 6. 50.