ISO 1461 vs ISO 2081 vs ISO 19598
Table 1: Scope and Process Overview
| Feature | ISO 1461 | ISO 2081 | ISO 19598 |
| Primary Process | Hot Dip Galvanizing: Dipping fabricated articles into molten zinc. | Electroplating: Electrodeposition of zinc. | Electroplating: Electrodeposition of zinc or zinc alloys. |
| Substrate | Fabricated iron and steel articles (including castings). | Iron or steel. | Iron or steel. |
| Coating Material | Molten zinc containing not more than 2% other metals. | Zinc. | Zinc OR Zinc Alloys (Zinc-Nickel, Zinc-Iron). |
| Key Exclusion | Does not apply to continuous sheet, wire, or automatic tube plants. | Does not apply to coatings on sheet, strip, or wire in non-fabricated form. | Not explicitly stated in Scope, but implies fabricated parts (rack/barrel). |
| Main Application | Heavy-duty corrosion protection (structural steel, outdoor furniture). | Protective and decorative purposes. | High-performance protection (automotive, high-stress) with strict environmental (CrVI-free) compliance. |
Table 2: Coating Thickness and Designation
| Feature | ISO 1461 | ISO 2081 | ISO 19598 |
| Typical Thickness | Thick: Generally 35 µm to 85 µm (mean) depending on steel thickness. | Thin: Typically 5, 8, 12, or 25 µm. | Thin: Typically 5, 8, 12 µm (up to ~25 µm). |
| Thickness Determination | Determined by steel thickness (e.g., steel >6mm requires 85 µm coating). | Determined by purchaser specification in the designation. | Determined by purchaser specification in the designation. |
| Designation Format | Reference to standard (e.g., “ISO 1461”). | Format: Fe/Zn[Thick]/[Passivation]/[Sealant] (e.g., Fe/Zn12/A). | Format: Fe//[Alloy][Thick]//[Passivation]//[Sealant] (e.g., Fe//ZnNi8//Cn//TO). |
| Alloy Options | Zinc/Iron alloy layers form naturally during the hot dip process. | Zinc only. | Zn (Zinc), ZnFe (0.3-1.0% Fe), ZnNi (12-16% Ni). |
Table 3: Supplementary Treatments (Passivation) & Environmental
| Feature | ISO 1461 | ISO 2081 | ISO 19598 |
| Passivation Chemistry | Not mandatory. “After-treatments” (e.g., to prevent wet storage stain) are allowed but not strictly defined by code. | Allows both Hexavalent Cr(VI) and Trivalent Cr(III) passivations, though warns of REACH bans on Cr(VI). | Strictly Cr(VI)-Free (Hexavalent chromium free) treatments only. |
| Treatment Codes | None specified in standard designation. | A (Clear), B (Bleached), C (Iridescent), D (Opaque), F (Black). | An (Transparent), Cn (Iridescent), Fn (Black). |
| Sealants | Not part of the standard designation. | Designated as T (e.g., T2 for organic sealant). | Designated as T (e.g., T2, T7 with optional integrated lubricant codes L/yL). |
| Hydrogen Embrittlement | Mentions venting/draining to prevent explosions. Low risk for standard steels. | Requires Stress Relief (SR) and Embrittlement Relief (ER) for steels ≥ 1000 MPa. | High Focus: Detailed diagrams on stress/material interaction. Mandatory relief for steels ≥ 1000 MPa. |
Table 4: Corrosion Resistance (Salt Spray – NSS)
| Feature | ISO 1461 | ISO 2081 | ISO 19598 |
| Basis of Resistance | Proportional to thickness. Life often predicted in decades (20+ years) in real atmosphere. | Dependent on passivation type and thickness. Measured in hours of Salt Spray Test. | Dependent on Alloy (Ni/Fe), passivation, and thickness. Measured in hours of Salt Spray Test. |
| Salt Spray Criteria | Warning: Accelerated tests (Salt Spray) should not be used to predict long-term corrosion performance. | Example (Rack, Zn12, Iridescent): • White rust: 120h • Red rust: 264h. | Example (Rack, Zn12, Iridescent): • White corrosion: 120h • Red rust: 264h. |
| Alloy Performance (NSS) | N/A | N/A | High Performance: ZnNi (Zinc-Nickel) can achieve 720h without red rust. |