Metallic and other inorganic coatings. Electroplated coatings of cadmium with supplementary treatments on iron or steel
1Key Takeaways
This document specifies requirements for cadmium coatings and supplementary treatments applied to iron and steel. It includes information to be furnished by the purchaser to the electroplater and describes the coating requirements, including heat treatment requirements before and after plating. The following coating ap…
2Expert Interpretation
Expert interpretation of BS EN ISO 2082:2017, covering technical requirements for cadmium electroplating on steel substrates, supplementary treatment processes, thickness measurement methods, and heat treatment specifications for hydrogen embrittlement relief. Key updates to the standard and application requirements for specific applications, such as aerospace, are also analyzed.
Comparison of key technical requirements
| Project | 2008 Edition | Main changes in the 2017 Edition |
|---|---|---|
| Environmental requirements | Permit hexavalent chromium conversion coating | Clear REACH regulation restrictions, recommend chromium-free alternatives |
| Hydrogen embrittlement treatment | Reference to ISO 9588 | Added ISO 15724 hydrogen diffusion measurement method |
| Coating thickness | Measurement of small parts is not clarified | Added average thickness measurement method for workpieces <100mm² in Appendix B |
Key Process Control Points
1. Coating Thickness Grading
Select thickness grade according to service environment:
- Fe/Cd5: Dry indoor environment (48h salt spray test)
- Fe/Cd25: Outdoor temperate climate (192h salt spray test)
2. Hydrogen Embrittlement Risk Control
Steel parts with tensile strength ≥1000MPa must undergo:
- Stress relief heat treatment (SR) before electroplating
- Hydrogen embrittlement relief heat treatment (ER) after electroplating
- Residual hydrogen detection according to ISO 10587
Implementation Recommendations
Precautions in the design phase
1. The effect of the coating on the mating dimensions must be considered for threaded parts.
2. Conversion coating type selection:
- Type A (transparent): ρA≤0.5g/m²
- Type D (black): ρA＞1.5g/m²
Special application scenarios
Note for the aerospace industry:
- Food contact components are prohibited
- Welding/heating operations require cadmium vapor protection measures