GB/T 1499.2-2018 governs hot-rolled ribbed round bars (HRB) used to reinforce concrete, with strict requirements to ensure bond strength and structural integrity:
Dimensions: Diameters 6–50mm with longitudinal ribs and transverse ribs (height ≥4% of diameter) to enhance grip with concrete.
Chemical composition: C ≤0.25%, Mn 1.00–1.60%, P ≤0.045%, S ≤0.045% for HRB400, with microalloys (Nb, V, Ti) to improve strength.
Mechanical properties: Yield strength ≥400 MPa, tensile strength ≥540 MPa, and elongation ≥16%-ensuring the bars can absorb seismic energy without snapping.
Testing: Mandatory tensile, bend, and rib geometry tests; bars ≥20mm require ultrasonic inspection to detect internal defects.
This standard aligns with ASTM A615 (USA) and EN 10080 (EU) for reinforced concrete applications, making GB/T 1499.2 bars suitable for high-rise buildings, bridges, and dams.