GB 1591 (China) and EN 10025 (EU) are parallel standards for low-alloy high-strength round bars, with key similarities and differences:
Grade equivalence: Q355 (GB 1591) ≈ S355 (EN 10025-2), with comparable yield strength (345 vs. 355 MPa) and tensile ranges (470–630 MPa). Both are used in bridges and heavy machinery.
Chemical composition: Q355 allows higher manganese (1.60% max) but lower copper (0.30% max vs. 0.50% max in S355), reflecting China's alloy availability and manufacturing practices.
Testing requirements: Both mandate tensile and bend tests, but EN 10025 includes stricter impact testing (e.g., -50°C for S355NL) for arctic applications, while GB 1591 focuses on ambient-temperature toughness.
Applications: Q355 dominates Chinese "Belt and Road" infrastructure projects, while S355 is preferred in EU wind farms and offshore structures, where low-temperature performance is critical.
This alignment allows for material interchangeability in global projects, supported by third-party certifications like TÜV or SGS.