HRB235 is grade I steel and HRB335 is grade II steel.

The Chinese name of HRB 400 is hot-rolled ribbed bar with a diameter of 6 ~ 100 mm ... The national mandatory standard GB 1499.2—2007 "Hot-rolled ribbed bar for reinforced concrete" has been implemented since March 1 2008. The new standard replaces GB 1499- 1998 "Hot-rolled Ribbed Reinforcement for Reinforced Concrete" and GB13014-1991"Reinforcement for Reinforced Concrete with Waste Heat", which is the same as the original standard GB/.

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HRB stands for hot rolled ribbed bar, that is, hot rolled ribbed bar. The so-called ribbed steel bar refers to the surface deformation of steel bar through hot rolling process to increase the bite force with concrete, including surface ribbed steel bar, spiral steel bar, herringbone steel bar and crescent steel bar.

HRB 400(20 mnsy, 20MnSiNb, 20MnTi), the standard value of steel yield strength is 400MPa, and the design value is 330MPa. The diameter is 6 ~ 50 mm, and the elastic modulus is 200GP.

Reference: Baidu Encyclopedia -HRB 400