Overview
ISO 14788:2017 specifies the minimum requirements for steel sheet metallic-coated by the continuous hot-dip process with a zinc-5 % aluminium alloy coating. It covers products supplied in coils and cut lengths and is intended for applications requiring corrosion resistance, formability and paintability. The standard defines quality designations and grades, coating types and finishes, surface treatments, and compatibility with different application requirements.
Key topics and requirements
ISO 14788:2017 addresses the technical and inspection elements needed to ensure consistent, fit-for-purpose coated steel sheet. Major topics include:
- Scope and definitions for commercial, drawing and structural qualities (e.g., deep drawing, interstitial-free steel).
- Conditions of manufacture: steelmaking, chemical composition, heat and product analysis.
- Mechanical properties: tensile testing and formability requirements for commercial, drawing and structural grades.
- Coating requirements: zinc-5 % aluminium alloy coating characteristics, coating mass, coating adherence and finish conditions (including normal spangle and smooth finish).
- Surface treatments and post-coating processing: skin pass, mill passivation, oiling and painting considerations to maintain paintability and corrosion protection.
- Weldability, dimensional and shape tolerances, and coil handling (coil joining, coil size).
- Sampling, test methods and acceptance criteria: tensile tests, coating mass measurement and adherence tests; related measurement methods are referenced.
- Designation, marking and purchaser information: clear system for specifying coating designation, coating mass, base-metal quality and finish condition.
Applications and practical value
ISO 14788:2017 is used where a balance of corrosion protection, formability and paintability is required. Practical advantages include:
- Providing a consistent specification for procurement and quality control of hot-dip zinc-5% aluminium coated steel sheet.
- Enabling predictable performance in forming operations (drawing, deep drawing) and downstream finishing such as painting.
- Supporting manufacturers and fabricators in maintaining coating adherence and surface condition for durable end products.
Typical application areas (where corrosion resistance and paintability are important) include building envelopes, architectural cladding, coated components in general fabrication, and other formed steel parts.
Who uses this standard
- Steel producers and coating line operators
- Fabricators, stampers and component manufacturers
- Specifiers, architects and engineers selecting coated steel
- Quality managers, inspection and testing laboratories
- Purchasing and procurement teams
Related standards
ISO 14788:2017 references and works alongside other standards for testing and tolerances, including:
Keywords: ISO 14788:2017, zinc-5% aluminium, hot-dip coated steel sheet, continuous hot-dip process, corrosion resistance, formability, paintability, coating mass, coating adherence.