Products Description
Ordinary carbon steel bolts installed outdoors or near the coast show red rust within months. Corrosion builds up in the threads, the fastener seizes, and removal turns into cutting and drilling - every maintenance round becomes unplanned downtime. The 304 stainless steel hex flange bolt is designed to stop this failure mode at the source.
Produced to DIN 6921 and ISO 4162 in A2-70 austenitic SUS304, it combines the hexagon head and load-bearing flange in one piece. The flange spreads the clamping load over a wider bearing surface, resists slipping, and keeps the joint tight under vibration and thermal cycling - with no separate washer to install and no plating that can wear off in service.
Technical Specifications
Complete specifications for procurement and engineering reference
| Product Name | Hex Flange Bolt, Hexagon Head with Integrated Flange |
|---|---|
| Standard | DIN 6921 / ISO 4162 |
| Material | 304 stainless steel (A2-70), minimum tensile strength 700 MPa |
| Thread Range | M5, M6, M8, M10, M12, M16, M20 - metric coarse pitch |
| Length Range | 8 mm – 350 mm; custom lengths on request |
| Flange Option | Standard flat flange / serrated (anti-vibration) flange |
| Salt Spray Test | 72 hours+ neutral salt spray (NSS), no red rust |
| Surface | Natural passivated finish - no plating required |
| Customization | OEM/ODM per customer drawings and technical parameters |
| MOQ | Negotiable, trial orders and samples supported |
| Packaging | Standard export packaging |
| Quote Turnaround | Within 24 hours |
Core Advantages
Why engineers specify SUS304 flange bolts for corrosive installations
Built-In Flange Locking
The integrated flange face spreads load and resists slip, replacing a separate washer and keeping joints tight under vibration.
72h+ Salt Spray Proven
Passes 72-hour+ neutral salt spray testing with no red rust - threads stay clean and removable after years outdoors.
No Coating to Fail
Corrosion resistance comes from the 304 material itself, not a zinc layer - scratches and edge wear never become rust points.
One-Piece, Faster Install
Head and flange in a single part: fewer components to stock, quicker assembly on site, lower total installed cost.
SUS304 Hex Flange Bolt vs Ordinary Hex Bolt
What changes when corrosion protection is built into the material
| Comparison Dimension | SUS304 Hex Flange Bolt | Ordinary Zinc-Plated Hex Bolt |
|---|---|---|
| Corrosion Protection | Inherent to the material, cannot wear off | Zinc layer only, wears and scratches off |
| 72h Salt Spray Test | Pass, no red rust | Red rust within months outdoors |
| Anti-Loosening | Integrated flange face, anti-slip by design | Plain bearing face, needs separate washer |
| Components per Joint | One piece | Bolt + flat washer + spring washer |
| Removal After Years Outdoors | Threads clean, reusable | Seized, often cut off |
| Lifecycle Cost | Lower - no replacement or downtime | Higher - repeated maintenance |
Professional Production Process
Standardized fastener manufacturing for consistent strength and precision
SUS304 Wire Rod Inspection
Cold Heading
Flange Forming
Thread Rolling
Passivation Treatment
72h Salt Spray Test & Final Inspection
Every batch is checked for thread accuracy, flange concentricity, and surface finish before shipment, and material certificates are available on request.
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SUS304 · A2-70
304 Stainless Steel (Standard)
Minimum tensile strength 700 MPa
72h+ neutral salt spray, no red rust
Natural passivated finish, no plating
Ideal for outdoor, coastal, and washdown use
Food-contact friendly austenitic surface
Optional Upgrades
316 Steel & Serrated Flange
316 (A4) stainless steel for splash zones
Serrated flange for high-vibration joints
Custom lengths and flange diameters
Non-standard thread pitches on request
Marking and packaging customization
Application Scenarios
Where a 304 stainless steel hex flange bolt outlasts plated fasteners
Outdoor PV Mounting Systems
Module clamps, rail splice joints, and grounding connections exposed to rain, UV, and daily temperature swings - installed once, serviced without seizure for the life of the plant.
Marine & Coastal Electrical
Enclosures, cabinets, and busbar supports in salt-fog atmospheres where plated bolts rust through in months and compromise both access and grounding continuity.
Food & Packaging Machinery
Frames and guards subject to daily washdown and cleaning chemicals - the passivated 304 surface stays bright and hygienic, with no coating flakes near product lines.
Frequently Asked Questions
Q:Will a 304 stainless steel hex flange bolt rust in coastal environments?
A:No. The A2-70 austenitic 304 body passes 72 hours or more of neutral salt spray testing without red rust. Because protection comes from the material rather than a coating, scratches do not turn into rust points. For permanent splash zones or heavy salt fog, a 316 (A4) upgrade is available.
Q：Does the flange face replace a separate washer or lock washer?
A:Yes. The integrated flange distributes clamping load over a wider bearing surface, so no separate flat washer is needed. For high-vibration joints, the optional serrated flange bites into the mating surface and mechanically resists loosening.
Q:What sizes are available and what is the MOQ?
A:Standard threads run M5 to M20 in metric coarse pitch, with lengths from 8 mm to 350 mm. Custom lengths and non-standard flange dimensions are produced to drawings. Trial orders and sample quantities are negotiable, and free samples are available for standard fasteners with freight collect.
Q:What is the delivery time and quality guarantee?
A:Quotes are returned within 24 hours. Standard sizes ship in export packaging with material certificates available on request. Every batch is inspected for thread accuracy and surface finish, and confirmed manufacturing defects are resolved through replacement or credit agreed directly with the customer.
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