GB/T 35505-2017Technical specification for sherardizing coatings on iron and steel articles (English PDF)
钢结构件渗锌耐蚀作业质量控制评定技术规范
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Issued by
SAMR; SAC
Level / Type
National · Recommended
Issue date
December 29, 2017
Implementation date
July 1, 2018
Scope
GB/T 35505-2017 is the English-translated version of 钢结构件渗锌耐蚀作业质量控制评定技术规范.
GB/T 35505-2017 is the Chinese standard "Technical Specification for Sherardizing Coatings on Iron and Steel Articles".
Its scope clause reads: This Standard specifies relevant terms, and technical requirements of quality control and assessment of sherardizing coatings anti-corrosion operation of iron and steel articles (hereinafter referred to as sherardizing operation).
This Standard is applicable to surface sherardizing operation of carbon steel, low-alloy steel and cast-iron components, fasteners and structural parts.
This Standard is not applicable to sherardizing operation of steel structural components that have precision requirements towards external dimension; steel structural components that bear soldered joints or organic material joints; steel structural components that need to be tempered at the temperature of 360 °C to satisfy the requirement of mechanical properties.
Its clauses include terms and definitions; technical requirements; quality control and assessment methods. It was issued by the General Administration of Quality Supervision, Inspection and Quarantine on DECEMBER 29, 2017 and took effect on JULY 1, 2018.
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Document preview — GB/T 35505-2017
National Standard of the People's Republic of China
- ICS
- 25.220.99
- Classification
- A 29
Issued by: State Administration for Market Regulation; Standardization Administration of the PRC
Contents
- Foreword3
- 1 Scope4
- 2 Normative References4
- 3 Terms and Definitions5
- 4 Technical Requirements5
- 5 Quality Control and Assessment Methods9
- Appendix A (informative appendix)11
1 Scope
This Standard specifies relevant terms, and technical requirements of quality control and assessment of sherardizing coatings anti-corrosion operation of iron and steel articles (hereinafter referred to as sherardizing operation).
This Standard is applicable to surface sherardizing operation of carbon steel, low-alloy steel and cast-iron components, fasteners and structural parts.
This Standard is not applicable to sherardizing operation of steel structural components that have precision requirements towards external dimension; steel structural components that bear soldered joints or organic material joints; steel structural components that need to be tempered at the temperature of 360 °C to satisfy the requirement of mechanical properties.
2 Normative References
The following documents are indispensable to the application of this Standard. In terms of references with a specified date, only versions with a specified date are applicable to this Standard. The latest version (including all the modifications) of references without a specified date is also applicable to this Standard.
GB/T 230.1 Metallic Materials - Rockwell Hardness Test - Part 1: Test Method (scales A, B, C, D, E, F, G, H, K, N, T)
GB/T 4956 Non-magnetic Coatings on Magnetic Substrates - Measurement of
Coating Thickness - Magnetic Method
GB/T 6462 Metallic and Oxide Coatings - Measurement of Coating Thickness -
Microscopical Method
GB/T 6890 Zinc Powder
GB/T 10125 Corrosion Tests in Artificial Atmospheres - Salt Spray Tests
GB/T 13912-2002 Metallic Coatings - Hot Dip Galvanized Coatings on Fabricated
Iron
3 Terms and Definitions
The following terms and definitions are applicable to this document.
3.1 Sherardizing
Sherardizing is an anti-corrosion method that forms a zinc-iron alloy coating on the surface by rotating and heating up steel structural components, zinc powder, additives and activators in a sealed container.
3.2 Sherardized Coatings
Sherardized coating refers to a zinc-iron alloy coating that is formed on the surface of steel structural components because of the mutual diffusion of zinc and iron atoms.
3.3 Sherardized Articles
Sherardized article refers to steel structural components that are processed through sherardizing throughout the process.
3.4 Colored Seal
Colored seal refers to the process of sealing sherardized coating on sherardized pieces with a colored material.
3.5 Colorless Seal
Colorless seal refers to the process of sealing sherardized coating on sherardized pieces with a colorless or transparent material.
3.6 Sherardized Anti-corrosion Coatings
Sherardized anti-corrosion coating is a compound anti-corrosion coating that is formed after sealing the sherardized coating.
4 Technical Requirements
4.1 Thickness Level of Sherardized Coatings
In accordance with the requirements of adopting steel structural components under different environments, sherardized coatings can be divided into several thickness levels. Thickness level of sherardized coatings shall comply with the stipulation in Table
1 below.
or eliminate reddish brown spots that are generated because of premature iron atom precipitation in sherardized coatings in accelerated corrosion test or application.
4.5 Performance of Sherardized Coatings
4.5.1 Appearance
4.5.1.1 There shall be no dust, excessive spot, delamination or stripping on the surface of the sherardized coatings; the appearance colors shall be uniform; there shall be no obvious chromatic aberration.
4.5.1.2 After sherardizing, fasteners shall have distinct and clean screw threads that will not affect the normal operation.
4.5.1.3 When sherardized articles’ defects (such as sand hole and slag inclusion, etc.)
lead to partial non-sherardized coatings after sherardizing, it shall not be deemed as quality defect.
4.5.2 Thickness
4.5.2.1 Thickness of the sherardized coatings shall comply with the stipulation in Table
1.
4.5.2.2 The sherardized coatings shall be uniform; thickness deviation of the sherardized coatings of the same sherardized article shall not be > 10% of the average thickness of the sherardized coatings.
4.5.3 Hardness
In terms of high-strength structural components, such as spring and high-strength fasteners, hardness test of base metal shall be conducted after sherardized. The result shall not be < the hardness of base metal before sherardizing.
4.5.4 Corrosion resistance
Neutral salt spray corrosion time of different thickness levels of sherardized coatings shall comply with the stipulation in Table 3 below.
Table 3 -- The Lowest Time Requirement of Red Rust Emerging after Neutral
Salt Spray Test
Thickness
Level
Red Rust
Emerging
Time/h
......
This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 15 pages — is available in the English PDF.
Referenced standards
Normative references
- GB/T 230.1Metallic materials - Rockwell hardness test - Part 1: Test method
- GB/T 4956Non-magnetic coatings on magnetic substrates - Measurement of coating thickness - Magnetic method
- GB/T 6462Metallic and oxide coatings - Measurement of coating thickness - Microscopical method
- GB/T 6890Zinc powder
- GB/T 10125Corrosion tests in artificial atmospheres - Salt spray tests
- GB/T 13912-2002Metallic coatings--Hot dip galvanized coatings on fabricated iron and steel articles--Specifications and test methods
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Related Standards
GB/T 10125-2021 — Corrosion tests in artificial atmospheres - Salt spray tests
GB/T 230.1-2018 — Metallic materials - Rockwell hardness test - Part 1: Test method
GB/T 4956-2003 — Non-magnetic coatings on magnetic substrates -- Measurement of coating thickness -- Magnetic method
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