GB/T 2518-2019
Continuously hot-dip zinc and zinc alloy coated steel sheet and strip (English Version)

Standard No.

GB/T 2518-2019

Language

Chinese, Available in English version

Release Date

2019

Published By

General Administration of Quality Supervision, Inspection and Quarantine of the People‘s Republic of China  CN  /  GB

Latest

GB/T 2518-2019

Replace

GB/T 2518-2008 GB/T 14978-2008

Introduction

1. Background of standard revision and technological evolution

GB/T 2518-2019 "Continuously hot-dip galvanized and zinc alloy coated steel sheets and strips" is an integration and upgrade of GB/T 2518-2008 and GB/T 14978-2008. The new standard combines the needs of domestic and foreign technological development, mainly adding coating weight terms, coating type expansion, and mechanical property optimization, while refining surface treatment requirements.

2. Standard classification system

This standard covers a variety of coating types, including hot-dip galvanizing (Z), zinc-iron alloy (ZF), zinc-aluminum alloy (ZA) and aluminum-zinc alloy (AZ). According to different application scenarios, the selection of coating type needs to be combined with material performance and corrosion resistance requirements.

Coating type	Features	Typical applications
Pure zinc coating (Z)	Strong sacrificial protection, suitable for general environment.	Building structural parts, automotive parts.
Zinc-iron alloy coating (ZF)	Excellent resistance to under-film corrosion, suitable for subsequent coating.	Body panels, home appliance housings.
Zinc-Aluminum Alloy Coating (ZA)	Enhanced corrosion resistance and good ductility.	Deep-drawing parts, industrial products.
Aluminum-Zinc Alloy Coating (AZ)	Outstanding electrochemical protection effect and excellent durability.	Roofing systems, high-strength structural parts.

3. Key Technical Requirements

3.1 Coating Weight and Thickness Control

The average value of the three-point test of the coating weight shall not be less than the specified nominal value, and the single-point test value shall not be less than 85%. For example, hot-dip galvanizing Z250 can be expressed as Z125/125 to ensure uniform thickness of the coating.

3.2 Surface treatment and quality

Surface treatment includes chromic acid passivation, oiling and anti-fingerprint film. Among them, trivalent chromium passivation and chromium-free passivation processes are gradually becoming environmentally friendly trends and are suitable for high-end manufacturing.

GB/T 2518-2019 Referenced Document

• GB/T 17505 Steel and steel products.General technical delivery requirements
• GB/T 1839-2008 Test method for gravimetric determination of the mass per unit area of galvanized coatings on steel products
• GB/T 20066 Steel and iron.Sampling and preparation of samples for the determination of chemical composition
• GB/T 20123 Steel and iron - Determination of total carbon and sulfur content Infrared absorption method after combustion in an induction furnace (routine method)
• GB/T 20125 Low-alloy steel.Determination of multi-element contents.Inductively coupled plasma atomic emission spectrometric method
• GB/T 20126 Unalloyed Steel - Determination of low carbon content - Part 2: Infrared absorption method after combustion in an induction furnace (With preheating)
• GB/T 223.12 Methods for chemical analysis of iron,steel and alloy--The sodium carbonate separation-diphenyl carbazide photometric method for the determination of chromium content
• GB/T 223.14 Methods for chemical analysis of iron,steel and alloy The N-benzoy-N-phenylhydroxylamine extraction photometric method for the determination of vanadium content
• GB/T 223.17 Methods for chemical analysis of iron,steel and alloy--The diantipyrylmethane photometric method for the determination of titanium content
• GB/T 223.26 Iron,steel and alloy.Determination of molybdenum content.The thiocyanate spectrophotometric method
• GB/T 223.40 Iron, steel and alloy Determination of niobium content by the sulphochlorophenol S spectrophotometric method
• GB/T 223.5 Steel and iron.Determination of acid-soluble silicon and total silicon content.Reduced molybdosilicate spectrophotometric method
• GB/T 223.59 Iron,steel and alloy.Determination of phosphorus content.Bismuth phosphomolybdate blue spectrophotometic method and antimony phosphomolybdate blue spectruophotometric method
• GB/T 223.60 Steel and alloys - Determination of silicon content - Gravimetric method*， 2024-04-25 Update
• GB/T 223.9 Iron,steel and alloy.Determination of aluminium content.Chrome azurol S photometric method
• GB/T 228.1-2010 Metallic materials.Tensile testing.Part 1: Method of test at room temperature
• GB/T 24174 钢 烘烤硬化值(BH)的测定方法*， 2022-04-15 Update
• GB/T 247 General Requirements for Packaging, Marking and Quality Certificate of Steel Plates and Steel Strips*， 2025-08-01 Update
• GB/T 25052-2010 Continuously hot-dip coated steel sheet and strip.Tolerances on dimensions,shape and weight
• GB/T 2975 Steel and steel products - Location and preparation of samples and test pieces for mechanical testing
• GB/T 4336 Determination of multi-element content in carbon steel and medium and low alloy steel Spark discharge atomic emission spectrometry (conventional method) Amendment No. 1
• GB/T 5027 Metallic materials - Thin plates and strips - Determination of plastic strain ratio (r-value)*， 2025-06-30 Update
• GB/T 5028 Metallic materials - Thin plates and strips - Determination of tensile strain hardening exponent (n-value)*， 2025-06-30 Update
• GB/T 8170 Rules of rounding off for numerical values & expression and judgement of limiting values
• ISO 6892-1:2016 Metallic materials - Tensile testing - Part 1: Method of test at room temperature

GB/T 2518-2019 history

• 2019 GB/T 2518-2019 Continuously hot-dip zinc and zinc alloy coated steel sheet and strip
• 2008 GB/T 2518-2008 Continuously hot-dip zinc-coated steel sheet and strip
• 2004 GB/T 2518-2004 Continuous hot-dip zinc-coated steel sheets and strips
• 1988 GB/T 2518-1988 Continual hot-dip zinc-coated steel sheets and strips

GB/T 2518-2019 Continuously hot-dip zinc and zinc alloy coated steel sheet and strip has been changed from GB/T 14978-2008 Continuously hot-dip aluminum-zinc alloy coated steel sheet and strip .

Topics on standards and specifications

Standard and Specification