ISO 630-6:2023

Overview

ISO 630-6:2023 - "Structural steels - Part 6: Technical delivery conditions for seismic-proof improved structural steels for building" defines delivery conditions, chemical and mechanical requirements, and testing for steels intended for seismic-proof structural use. It applies to hot-rolled plates, wide flats and hot-rolled sections (as-rolled unless otherwise agreed), covering five steel grades (SA235, SA325, SA345, SA390, SA440) and up to seven qualities. The standard targets members of the construction supply chain who need consistent, verifiable material performance in seismic regions.

Key topics and technical requirements

• Grades and qualities: SA235, SA325, SA345, SA390 and SA440 are specified. Qualities A, C, C+, D, D+, E and E+ define different impact-testing regimes (e.g., 0 °C, −20 °C, −40 °C) and whether through‑thickness testing is required.
• Product scope and dimensions: Applicable to hot‑rolled plates (nominal thickness 6–150 mm) and wide flats/hot‑rolled sections (nominal thickness up to 140 mm). Sheet, strip and tubular products are excluded.
• Delivery condition: Generally delivered as‑rolled; SA440 is normally quenched & tempered or produced by thermomechanical controlled process (TMCP). TMCP may be applied if agreed between purchaser and manufacturer.
• Chemical composition & product analysis: Heat analysis limits are specified per grade; permitted deviations for product analysis (e.g., C +0.03 %, Si +0.05 %, Mn ±0.10 %, P +0.005 %, S +0.005 %) are defined.
• Carbon equivalent (CEV): CEV requirements are given by grade and thickness; CEV is calculated using the IIW formula to assess weldability and crack susceptibility.
• Mechanical testing: Tensile properties, Charpy V‑notch impact testing (transverse direction optional), and through‑thickness characteristics testing (for “+” qualities) are required. Sampling frequency, inspection and test methods are specified.
• Marking, tolerances and inspection: Requirements cover marking, dimensional tolerances, internal soundness and sampling procedures.

Practical applications

• Ensures consistent material performance for seismic-resistant buildings and structural components.
• Guides steel producers on delivery specifications and allowable chemistries.
• Provides fabricators, structural engineers and procurement teams with objective criteria for material selection, testing and acceptance.
• Used by certification bodies and regulators to verify compliance in seismic design contexts.

Who should use this standard

• Steel mills and manufacturers of plates, wide flats and hot-rolled sections
• Structural engineers, design offices and fabricators working on seismic-prone buildings
• Procurement, quality assurance and testing laboratories verifying material conformity

Related standards

• ISO 630-1 (general technical delivery conditions)
• ISO 7452 (plate tolerances)
• ISO 9034 (wide flats tolerances)
• ISO 7778 (through-thickness characteristics)

Keywords: ISO 630-6, structural steels, seismic-proof, technical delivery conditions, SA235, SA325, SA345, SA390, SA440, Charpy V‑notch, carbon equivalent (CEV), thermomechanical controlled process, hot‑rolled plates.