GB/T 702 governs Chinese hot-rolled round bars, with strict quality controls:
Dimensional tolerances: ±0.3 mm for diameters 10–30 mm, verified via laser measurement to ensure compatibility with standard fasteners.
Mechanical testing: Mandatory tensile tests for yield (≥235 MPa for Q235) and tensile strength (≥375 MPa), with 25% minimum elongation for ductility.
Surface quality: No cracks or folds, inspected via visual and magnetic particle testing for critical applications like construction rebar.
These standards align with ISO 683-1, allowing GB/T 702 bars (e.g., Q235, Q355) to compete globally-exports to Southeast Asia reached 800,000 tons in 2023, primarily for infrastructure projects.