Deformed steel bars is a ribbed steel bar, also known as ribbed bar, usually with two longitudinal ribs and transverse ribs evenly distributed along the length. The shape of the transverse rib is three kinds of spiral shape, herringbone shape and crescent shape. Expressed in millimeters of nominal diameter. The nominal diameter of a ribbed bar corresponds to the nominal diameter of a round bar of equal cross-section. The nominal diameter of the steel bars is 8-50 mm. The recommended diameters are 8, 12, 16, 20, 25, 32, 40 mm. Ribbed steel bars are mainly subjected to tensile stress in concrete. The ribbed steel bar has a greater bonding ability with concrete due to the action of the ribs, and thus can better withstand the external force. Ribbed bars are widely used in a variety of building structures, particularly large, heavy, lightweight, thin-walled and high-rise building structures.
Rebar is produced by small mills. The main types of small mills are: continuous, semi-continuous and horizontal. Most of the world’s new and in-use small continuous rolling mills. Popular rebar mills have a universal high-speed rolling rebar mill and a 4-pile high-volume rebar mill.
The billet used in the continuous small rolling mill is generally a continuous casting billet, and its side length is generally 130-160 mm, the length is generally about 6-12 meters, and the billet weight is 1.5~3 tons. The rolling lines are mostly arranged in a flat-upright manner, achieving full-line non-twisting rolling. According to different blank specifications and finished product sizes, there are 18, 20, 22, and 24 small rolling mills, and 18 are the mainstream. Bar rolling is mostly carried out by step-type heating furnace, high-pressure water descaling, low-temperature rolling, headless rolling and other new processes. The rough rolling and medium rolling are developed to adapt to large billets and improve rolling precision. The finishing mill is mainly Improve accuracy and speed (up to 18m/s). Product specifications are generally ф10-40mm, also ф6-32mm or ф12-50mm. The steel grades produced are low-medium-high-carbon steels and low-alloy steels that are in large demand in the market; the maximum rolling speed is 18m/s.
The quality of the appearance of the screw steel:
1 surface quality. In the relevant standards, the surface quality of rebar is specified. The end shall be straight and the surface shall be free from cracks, crusting and folding, and there shall be no harmful defects in use.
2 The allowable value of the dimensional deviation. The requirements for the tortuosity of the rebar and the geometry of the reinforcement are specified in the relevant standards.
Screw steel needs attention:click
The finished product quality of the reinforced bar varies with the metallurgical smelting furnace and the hot rolling batch process. The furnace number and batch number are the basis of the sampling inspection. Therefore, the import and collection department and the warehousing department should pay attention to the mark on the goods, and the export enterprises and foreign trade departments should also sort out the batches, furnace numbers and provide quality certificates according to the standard requirements.
Rebar is generally delivered in bare bundles. Pay attention to moisture during storage. Corrosion will adversely affect the performance of rebar.