1. Different shapes: the outer surface of round steel is smooth; the outer surface of rebar has spiral ribs.
2. Different production standards: In the current standards, round steel refers to HPB235 grade steel bars, and its production standard is "Hot-rolled smooth steel bars for reinforced concrete" (GB13013); threaded steel generally refers to HRB335 and HRB400 grade steel bars, and its production The standard is "Hot-rolled ribbed steel bars for reinforced concrete" (GB1499).
3. Different strengths: The design strength of round steel (HPB235) is 210MPa; the strength of rebar is higher than that of round steel, the design strength of HRB335 is 300MPa; the design strength of HRB400 is 360MPa.
4. Different steel types (different chemical compositions): round steel (HPB235) is carbon steel, the steel type is Q235; threaded steel is low alloy steel, HRB335 grade steel bar is 20MnSi (20 manganese silicon); HRB400 grade steel bar is 20MnSiV or 20MnSiNb or 20MnTi, etc.
5. Different physical and mechanical properties: Due to the different chemical composition and strength of steel bars, the physical and mechanical properties are different. Round steel has better cold-bending performance and can be used to make 180-degree curved hooks, while rebar can only be used to make 90-degree straight hooks; round steel has good weldability, and ordinary carbon welding rods can be used, while rebar must be made of low-carbon welding rods. Alloy welding rod; rebar is better than round steel in terms of toughness and fatigue resistance.
