ISO 4998:2023

Overview

ISO 4998:2023 specifies requirements for steel sheet, zinc‑coated and zinc‑iron alloy‑coated by the continuous hot‑dip process, of structural quality. Intended for applications where corrosion resistance is a primary concern, the standard covers product grades, coating types (zinc and zinc‑iron), coating masses, surface finishes, surface treatments, mechanical requirements and inspection/acceptance criteria. This seventh edition (2023) updates terms and adds coating‑mass designations.

Keywords: ISO 4998:2023, zinc‑coated steel sheet, zinc‑iron alloy‑coated, continuous hot‑dip, structural quality, corrosion resistance.

Key topics and technical requirements

• Scope and product definition: Applies to structural‑quality hot‑dip zinc (Zn) and zinc‑iron (ZF) alloy coatings; excludes commercial or drawing quality (see ISO 3575).
• Dimensions and formats: Product thickness after coating typically ranges from 0.25 mm to 5 mm; produced in coils and cut lengths (widths ≥ 600 mm considered coils).
• Steelmaking and chemical composition: Requirements for base‑metal chemistry and methods for heat and product analysis are specified.
• Mechanical properties: Tensile properties, elongation and bend‑test requirements are included; tensile testing references ISO 6892‑1.
• Coating specifications:
  • Coating mass defined and expressed in g/m2 (total both sides).
  • Coating types and finishes (normal coating, minimized spangle, zinc‑iron alloy) and coating adherence tests.
  • Differential coating (different masses on each face) permitted where specified.
• Surface treatment and finishing: Mill passivation, mill phosphating, oiling, and skin‑pass rolling (to control surface and shape) are addressed.
• Weldability, painting and workmanship: Guidance for suitability for welding and painting; paintability of ZF (zinc‑iron) coatings noted.
• Sampling, testing and inspection: Sampling plans and specific tests for coating mass (ISO 1460), coating thickness (ISO 2178 / ISO 3497), bend tests (ISO 7438), and dimensional/shape tolerances (ISO 16163).
• Designation, marking and purchaser information: Standardized designation system, coil size, marking and order information requirements.

Applications and users

• Typical applications: structural components, building envelopes, roofing, cladding, infrastructure and any application needing durable corrosion protection.
• Who uses it: steel producers, galvanizers, fabricators, architects, structural engineers, procurement/specification writers, coating and corrosion engineers, and regulatory bodies.

Related standards

• ISO 3575 (commercial/drawing quality steel sheet)
• Test and measurement standards referenced: ISO 1460, ISO 2178, ISO 3497, ISO 6892‑1, ISO 7438, ISO 16163.

Use ISO 4998:2023 when specifying hot‑dip zinc or zinc‑iron coated structural steel sheet to ensure consistent corrosion performance, defined mechanical properties and clear interchangeability between suppliers.