Hot-rolled steel bars are finished steel bars that have been hot-rolled and naturally cooled. They are made of low-carbon steel and ordinary alloy steel at high temperature. They are mainly used for reinforcement of reinforced concrete and prestressed concrete structures. One of the most widely used steel varieties.

1. Hot-rolled steel bars are graded according to the standard value of yield strength and are divided into four grades:

HPB235 (Q235), the standard value of the yield strength of this steel bar is 235MPa, the diameter is 8-20mm, and the elastic modulus is 210GPa.

HRB335 (20MnSi), the standard value of the yield strength of this steel bar is 335MPa, the diameter is 6-50mm, and the elastic modulus is 200GPa.

HRB400 (20MnSiV, 20MnSiNb, 20MnTi), the standard value of the yield strength of this steel bar is 400MPa, the diameter is 6-50mm, and the elastic modulus is 200GPa.

RRB400 (K20MnSi), the standard value of the yield strength of the steel bar is the same as that of the HRB400 steel bar, which is also 400MPa, the diameter is 8-40mm, and the elastic modulus is 200GPa.

2. According to the different hot rolling process, it can be divided into the following three types:

HPB is the abbreviation of Hot-rolled Plain Bar.

HRB is the abbreviation of Hot-rolled Ribbed Bar. The so-called ribbed steel bar refers to the deformation of the surface of the steel bar by hot rolling process to increase the occlusal force between the concrete and the surface, including surface ribbed steel bar, helical steel bar, herringbone steel bar, Crescent grain steel bars, etc.

RRB is the abbreviation of Remained heat treatment Ribbed steel Bars, that is, residual heat treatment steel bars, which are finished steel bars obtained by piercing water immediately after hot rolling, performing surface control cooling, and then using the residual heat of the core to complete the tempering treatment. This kind of steel bar is also a hot-rolled steel bar, and its welding performance is different from that of HRB steel bar, and its ductility and strength-to-yield ratio are slightly lower.