Hot-Dip Galvanized Hex Bolts M12–M64 Grade 8.8 for Outdoor Steel Structure
Hot-dip galvanized hex bolts manufactured per ISO 1461 / ASTM A153. Grade 4.6 / 8.8 carbon steel hex bolts with full or partial thread, galvanized to minimum 70 μm coating thickness. Salt spray tested to 1000+ hours in our in-house laboratory.
Applications
- Outdoor steel structures (buildings, warehouses, stadiums)
- Highway guardrail & signage structures
- Telecom & power transmission towers
- Water treatment plant structures
- Solar mounting structures
- Marine & coastal infrastructure
- Agricultural & industrial buildings
Product Specification
| Parameter | Range |
|---|---|
| Type | Hex head bolt, full thread or partial thread |
| Standard | ISO 4017 (full thread) / ISO 4014 (partial thread) / DIN 933 / DIN 931 |
| Grade | 4.6 / 8.8 per ISO 898-1 |
| Size Range | M12 – M64 |
| Thread | Metric coarse (ISO 261) |
| Surface Treatment | Hot-dip galvanized per ISO 1461 |
| Coating Thickness | ≥ 70 μm (local) / ≥ 85 μm (average) |
Mechanical Properties (Per ISO 898-1)
| Property Class | UTS (MPa) | Yield (MPa) | Hardness (HV) | Coating |
|---|---|---|---|---|
| 4.6 | 400 | 240 | 120 – 250 | HDG per ISO 1461 |
| 8.8 | 800 | 640 | 250 – 320 | HDG per ISO 1461 |
Coating Specification
| Parameter | Requirement | Standard |
|---|---|---|
| Min coating thickness (local) | ≥ 70 μm | ISO 1461 |
| Min coating thickness (average) | ≥ 85 μm | ISO 1461 |
| Adhesion | No flaking after bending test | ISO 1461 |
| Appearance | Smooth, continuous coating, no bare spots, dross, or flux inclusions | ISO 1461 |
| Salt spray resistance | 1000+ hours to first white rust | ISO 9227 (NSS test, in-house lab) |
Hydrogen Embrittlement Control
Important: For bolts of Grade 10.9 and above (≥ 1000 MPa UTS), hot-dip galvanizing introduces hydrogen embrittlement risk. We apply documented bake procedures (pre-galvanizing bake 200°C ≥ 4h, post-galvanizing bake 200°C ≥ 24h) and delayed testing per ISO 10684 Annex B.
For Grade 8.8 and below, standard galvanizing practice is sufficient — no hydrogen embrittlement concern.
Standards Coverage
| Standard | Scope |
|---|---|
| ISO 4017 | Hex head bolts — full thread (product grade A/B) |
| ISO 4014 | Hex head bolts — partial thread (product grade A/B) |
| ISO 1461 | Hot-dip galvanized coatings on fabricated steel articles |
| ASTM A153 | Zinc coating (hot-dip) on iron and steel hardware |
| ISO 898-1 | Mechanical properties of fasteners — carbon & alloy steel |
| ISO 9227 | Salt spray (NSS) corrosion testing method |
Quality Assurance
- Salt spray test: 1000+ hours NSS (in-house laboratory, per ISO 9227)
- Coating thickness: magnetic gauge per ISO 2178, multiple readings per bolt
- Visual inspection: coating continuity, surface finish, absence of defects
- Base material testing: tensile & hardness per ISO 898-1 (before galvanizing)
- Adhesion test: knife test / bend test per ISO 1461
- Dimensional inspection: thread gauge GO/NO-GO, length, across-flats, head height
- Inspection report with every shipment
- Third-party inspection: SGS / BV / TÜV available
Why Source From SINOFASTENER
SINOFASTENER is an integrated manufacturer and trader. Our capability is not limited to this catalog — custom coatings, non-standard sizes, special lengths, project-specific drawings: if your project requires it, we manufacture and supply it.
- In-house salt spray lab — 1000H+ testing before every bulk order ships
- M12–M64 full range — one source for all standard sizes
- Full or partial thread — per ISO 4017 (full) or ISO 4014 (partial) to your specification
- Own packaging factory — pre-sorted by size, bagged, labeled, palletized to your warehouse spec
- EU trade advantage:
- Anti-dumping duty: 39.6% (TARIC C824) vs. 86.5% (C999)
- CBAM measured carbon: 1.698 tCO₂/t vs. EU default 7.013 — 93.5% lower
Packaging & Delivery
- Standard: 25 kg carton + pallet
- Custom: customer-branded packaging, barcode labels, bin-ready packs
- Anti-rust: no additional treatment needed (HDG is self-protecting)
- Lead time: 15–20 days for standard sizes, 25–30 days for large diameter or custom
Get a Quote
Send your bolt specification (size, grade, thread type, quantity). We return pricing with salt spray test report and coating certificate within 24 hours.
Email:sales@sinofastener.com
Frequently Asked Questions
Q1: What is the difference between ISO 4017 and ISO 4014 hex bolts?
ISO 4017 specifies full-thread hex bolts (thread runs the entire shank length). ISO 4014 specifies partial-thread hex bolts (thread only on a portion of the shank, with a plain grip length). Partial-thread bolts are preferred for structural connections where the unthreaded shank provides shear resistance. We supply both types in M12–M64.
Q2: What salt spray resistance do your HDG hex bolts achieve?
Our hot-dip galvanized hex bolts consistently achieve 1000+ hours to first white rust in neutral salt spray (NSS) testing per ISO 9227. Test results are documented in our in-house laboratory and included with every bulk order shipment. Coating thickness is verified at ≥ 70 μm (local) / ≥ 85 μm (average) per ISO 1461.
Q3: Can Grade 8.8 hex bolts be hot-dip galvanized safely?
Yes. Grade 8.8 (UTS 800 MPa) is well within the safe range for hot-dip galvanizing. Hydrogen embrittlement is only a concern for Grade 10.9 and above (≥ 1000 MPa UTS). For Grade 8.8, standard pickling, fluxing, and galvanizing practice is sufficient — no pre-bake or post-bake de-hydrogen treatment is required.
Q4: What coating thickness is applied to your HDG hex bolts?
Per ISO 1461, we apply a minimum of 70 μm local thicknessand85 μm average thickness. This provides excellent corrosion protection for outdoor and marine atmospheric environments (C3–C5 corrosion category per ISO 12944). Coating thickness is measured on every bolt using magnetic gauge per ISO 2178.
Q5: What size range and lengths can you supply?
We supply hot-dip galvanized hex bolts from M12 to M64 in both full-thread (ISO 4017) and partial-thread (ISO 4014) configurations. Standard lengths range from 20 mm to 300 mm; longer lengths available upon request. All bolts are manufactured to ISO product grade A or B depending on size and tolerance requirements.
For complete product catalog and company information, visit www.sinofastener.com
