Korea standard steel is also known as the deformed bars, surface bamboo shaped protrusions square or round steel, used for reinforced concrete, than the general square steel and round steel with more firmly. Early domestic steelform is bamboo, then reference the British standard, is now hot rolled ribbed steel bar, JIS and Korean standard screw thread steel or bamboo form.

Hot rolled reinforced bar should have a certain strength, i.e. the yield point and tensile strength, it is the main basis for structure design. At the same time, in order to meet the structural deformation, absorb the earthquake energy andprocessing requirements, hot rolled reinforced bar should also have theplasticity, toughness, welding and bonding properties between steel bar and concrete good.

Classification

Reinforced grade

The strength grade of 24/38 kg, is made of round steel bar killed steel, semi killed steel rimmed steel No. 3 or ordinary carbon steel rolling. It belongs to the low strength steel, has good plasticity, high elongation (delta 5 above 25%),easy bending forming, easy welding etc.. It is used very widely, can be used asthe main force in the reinforcement of reinforced concrete structure, small,member of the stirrups, steel, wood structure of the rod. Wire rod steel can be used as cold drawn low carbon steel wire and double reinforced materials.

II grade reinforced bar

Low alloy steel rolling or semi killed steel reinforced with grade II, with silicon,manganese as solid solution strengthening elements. Level II steel bar intensity level of 34 (32) /52 (50) kg, its high strength, good plasticity, the welding performance is good. The surface of steel rolling longitudinal rib longand uniformly distributed transverse rib, thereby strengthening the bondbetween concrete and steel bars. As with level II steel reinforced concretestructure stress of reinforced, than the use of reinforced grade of steel can be saved 40 ~ 50%. Therefore, widely used in large and medium-sized steel reinforced concrete structure, such as the main reinforcement of bridges,dams, port engineering and building structure. Level II steel after cold drawing,can also be used as prestressing steel building structure.

Grade

III main performance level II steel reinforced with roughly the same strengthlevel for 38/58 kg. Grade was renamed the HRB400 Grade Reinforced bar.Simply put, the same point of the two kinds of steel bar is: all belong to thecommon low alloy hot rolled reinforced bar; belong to the ribbed bar (usually said that the thread bars); can be used for ordinary reinforced concrete structure.

IV grade reinforced bar

IV reinforced the strength level of 55/85 kg, medium carbon low alloy killed steel rolling, which are divided by silicon, manganese as main alloy elements,also adding vanadium or titanium as solid solution and precipitationstrengthening elements, which increases the strength at the same time ensure its plasticity and toughness. Grade rebar surface is rolled with the longitudinal reinforcement and transverse rib, which is the main housing construction of theprestressed reinforced. Reinforcing bar of grade before use by the construction unit for cold processing, cold stress is 750 MPa, in order to improve the yield point, exert the inherent potential of steel products, achieve the purpose of saving steel. The cold drawn steel bar, the yield point is not obvious, so the design in cold stress Statistics (cold drawing design strength)as the basis. But the cold had reinforced after months of natural aging orartificial heating aging, reinforced will appear short yielding stage, its value is slightly higher than that of cold stress, at the same time the steel withhardened tendency, this phenomenon is called "age hardening". Therefore,cold drawn steel while guaranteeing the provisions of cold stress, to control thecold drawing elongation but, lest reinforced brittle. IV grade steel with high carbon content, the general use of flash butt welding - warm - flash welding ortechnology electric heat treatment after welding, to ensure that the weldinghead, including the heat affected zone of hard tissue does not producequenching, prevent the occurrence of brittle fracture. IV grade reinforced bardiameter is 12 millimeter commonly and widely used in prestressed concreteslabs and bundle configuration for components of large prestressedconstruction (such as the roof, crane beam). Hot rolling reinforcing bar of grade as prestressed reinforced when in use, still need to be drawn, welding,its strength is low, the need to further improve.

Finishing rolling rebar

In order to solve the problem of large diameter and high strength prestressed reinforcement and anchorage connection problems, has been developed successfully finishing rolling rebar. It is in the direct rolling steel surface withoutlongitudinal reinforcement and transverse rib reinforced trapezoidal screw buckle shape, available connection sleeve connected with long, with a specialnut as anchorage. This steel has been used in large scale prestressed concrete structure, bridge structure, success.