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FULLERKREG DIN 7349 thick flat washers are manufactured to DIN 7349 standard in A4 marine-grade stainless steel (SUS316 / 1.4401) with a natural cleaned and passivated finish. DIN 7349 washers are specifically designed for use with bolts that have heavy-type spring pins (DIN 7346 / ISO 8752), featuring a larger outer diameter and greater thickness than standard DIN 125 flat washers for superior load distribution. A4 stainless steel adds 2–3% molybdenum to the A2 (SUS304) composition, delivering significantly enhanced resistance to chloride corrosion, seawater, and aggressive chemical environments — the preferred choice for marine, offshore, and coastal applications.
All dimensions in millimeters (mm). Tolerances per DIN 7349.
| Nominal Size (d) | Inner Dia. d1 | Outer Dia. d2 | Thickness h | Weight (g/100 pcs) |
|---|---|---|---|---|
| M5 | 5.3 | 15 | 2.0 | 114 |
| M6 | 6.4 | 18 | 2.5 | 214 |
| M8 | 8.4 | 24 | 3.0 | 495 |
| M10 | 10.5 | 30 | 3.5 | 1,040 |
| M12 | 13.0 | 37 | 4.0 | 2,100 |
| M16 | 17.0 | 50 | 5.0 | 5,800 |
| M20 | 21.0 | 60 | 6.0 | 12,400 |
| M24 | 25.0 | 72 | 6.0 | 20,600 |
* All dimensions conform to DIN 7349. Please verify with your engineering team for critical applications.
| Property | Value |
|---|---|
| Material Grade | A4 / SUS316 / 1.4401 |
| Steel Group | Austenitic |
| Property Strength Class | 50, 70, 80 |
| Tensile Strength (Rm) | ≥ 500 MPa (Class 50) / ≥ 700 MPa (Class 70) / ≥ 800 MPa (Class 80) |
| Hardness (HV) | ≤ 250 HV (Class 50/70) / ≤ 330 HV (Class 80) |
| Density | 7.98 g/cm³ |
| Molybdenum (Mo) Content | 2.0 – 3.0% — key differentiator vs. A2 |
| Magnetic | Non-magnetic (austenitic) |
| Operating Temperature | -196°C to +400°C |
| RoHS / REACH | Compliant |
Per DIN EN ISO 3506-1. Strength class marking: A4-50, A4-70, or A4-80.
| Element | C (max) | Cr | Ni | Mo | Mn (max) | Si (max) | P (max) | S (max) |
|---|---|---|---|---|---|---|---|---|
| Content (%) | 0.07 | 16.5 – 18.5 | 10.5 – 13.5 | 2.0 – 3.0 | 2.0 | 1.0 | 0.045 | 0.030 |
Per DIN EN ISO 3506-1, A4 stainless steel washers are available in the following strength classes:
| Steel Group | Grade | Strength Class | Made From | Characteristics |
|---|---|---|---|---|
| Austenitic | A4 | 50 | A3, A4 | Soft annealed; tensile strength ≥ 500 MPa; dia. ≤ M39 |
| A4 | 70 | A3, A4 | Cold worked, normal strength; tensile strength ≥ 700 MPa; dia. ≤ M39 | |
| A4 | 80 | AC, AF | Extreme cold worked, high strength; tensile strength ≥ 800 MPa; dia. ≤ M20 |
| Property | A4 (SUS316) | A2 (SUS304) |
|---|---|---|
| Molybdenum (Mo) | 2.0 – 3.0% | None |
| Chloride resistance | Excellent — seawater & coastal | Good — atmospheric only |
| Acid resistance | Superior (sulfuric, phosphoric) | Moderate |
| Pitting resistance | High (Mo inhibits pitting) | Standard |
| Max strength class | A4-80 | A2-70 |
| Recommended environment | Marine, offshore, chemical, food | General outdoor, fresh water |
| Cost | Higher (Mo premium) | Standard |
| Feature | DIN 7349 | DIN 125 |
|---|---|---|
| Type | Thick flat washer (heavy type) | Standard flat washer |
| Outer Diameter | Larger (extra-wide bearing surface) | Standard |
| Thickness | Greater (heavy duty) | Standard |
| Designed for | Bolts with heavy spring pins (DIN 7346) | General-purpose bolts & screws |
| Load Distribution | Superior — wider bearing area | Standard |
| Application | Heavy machinery, structural, high-vibration | General assembly |
Real product images — FULLERKREG DIN 7349 Thick Flat Washer, A4 Marine Stainless Steel:
| [ Photo 1 ] | [ Photo 2 ] | [ Photo 3 ] | [ Photo 4 ] |
| Size | Standard Pack (pcs) | Bulk Carton (pcs) | Weight per 100 pcs (approx.) |
|---|---|---|---|
| M5 | 100 | 5,000 | ~114 g |
| M6 | 100 | 3,000 | ~214 g |
| M8 | 50 | 2,000 | ~495 g |
| M10 | 50 | 1,000 | ~1,040 g |
| M12 | 25 | 500 | ~2,100 g |
| M16 | 25 | 200 | ~5,800 g |
| M20 | 10 | 100 | ~12,400 g |
| M24 | 10 | 50 | ~20,600 g |
Custom packaging and labeling available for OEM / wholesale orders. Contact FULLERKREG for bulk pricing.
Q: What is the main advantage of A4 over A2 stainless steel?
A: A4 (SUS316) contains 2–3% molybdenum, which significantly enhances resistance to chloride pitting, seawater corrosion, and aggressive acids. A2 (SUS304) is suitable for general atmospheric and freshwater use, but A4 is required wherever chloride exposure is a concern.
Q: What is DIN 7349 and how does it differ from DIN 125?
A: DIN 7349 is a thick flat washer designed for bolts with heavy-type spring pins (DIN 7346). Compared to DIN 125, DIN 7349 washers have a larger outer diameter and greater thickness, providing a wider bearing surface and better load distribution in heavy-duty applications.
Q: Is A4 stainless suitable for full seawater immersion?
A: A4 (SUS316) performs well in seawater splash zones and salt-air environments. For continuous full immersion in seawater, super duplex or higher-grade alloys may be considered for critical structural applications. Contact FULLERKREG for application-specific guidance.
Q: What strength class are these washers supplied in?
A: Standard supply is A4-70. A4-50 and A4-80 are available upon request. Please specify your required strength class when ordering.
Q: Are these washers RoHS compliant?
A: Yes. FULLERKREG A4 stainless steel washers are fully RoHS and REACH compliant. Compliance documentation is available upon request.
Q: Do you provide material test certificates?
A: Yes. Mill certificates, chemical composition reports, and dimensional inspection reports are available for all orders upon request.
FULLERKREG Fasteners — Precision DIN Standard Fasteners, Direct from Manufacturer.
For wholesale inquiries, technical questions, or custom orders, please contact our sales team.
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