DIN 7349 Thick Flat Washer — Low Carbon Steel, Zinc CR3

FULLERKREG DIN 7349 thick flat washers are manufactured to DIN 7349 standard in low carbon steel with a Zinc CR3 (trivalent chromium) electroplated 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 and bearing surface. The Zinc CR3 finish delivers reliable corrosion protection with full RoHS compliance — the modern, environmentally safe alternative to hexavalent chromium coatings.

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Product Highlights

• Standard: DIN 7349
• Material: Low Carbon Steel (C ≤ 0.20%)
• Surface Treatment: Zinc Electroplated, Trivalent Chromium Passivation (CR3 / Blue-White)
• Corrosion Resistance: ≥ 72 hours salt spray (neutral, NSS) per ISO 9227
• Size Range: M5 – M24
• Designed for: Bolts with heavy-type spring pins (DIN 7346 / ISO 8752)
• Feature: Extra-large OD and increased thickness vs. DIN 125 — superior load distribution
• RoHS & REACH Compliant — no hexavalent chromium (Cr6+)

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Dimensional Specifications — DIN 7349 Thick Flat Washers (Steel, Zinc CR3)

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	107
M6	6.4	18	2.5	201
M8	8.4	24	3.0	465
M10	10.5	30	3.5	977
M12	13.0	37	4.0	1,974
M16	17.0	50	5.0	5,452
M20	21.0	60	6.0	11,660
M24	25.0	72	6.0	19,370

* All dimensions conform to DIN 7349. Weight values based on steel density ≈7.85 g/cm³. Please verify with your engineering team for critical applications.

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Material & Mechanical Properties — Low Carbon Steel

Property	Value
Material	Low Carbon Steel (C ≤ 0.20%)
Hardness (HV)	100 – 200 HV
Tensile Strength	≥ 300 MPa
Surface Treatment	Zinc Electroplating + CR3 Trivalent Chromium Passivation
Coating Thickness	5 – 12 μm (typical)
Salt Spray Resistance	≥ 72 hours (ISO 9227 NSS)
Operating Temperature	-40°C to +120°C
RoHS / REACH	Compliant — No hexavalent chromium (Cr6+)

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Chemical Composition — Low Carbon Steel

Element	C	Mn	P (max)	S (max)	Si
Content (%)	≤ 0.20	0.30 – 0.60	0.045	0.045	≤ 0.35

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Surface Treatment — Zinc CR3 Explained

CR3 (trivalent chromium) passivation is the modern, environmentally compliant alternative to traditional hexavalent chromium (CR6) coatings. FULLERKREG Zinc CR3 washers offer:

• ✅ RoHS & ELV compliant — no Cr6+ hazardous substances
• ✅ Blue-white bright appearance — clean, professional finish
• ✅ ≥ 72 hours neutral salt spray resistance (ISO 9227)
• ✅ Uniform coating — consistent 5–12 μm thickness across all surfaces
• ✅ Suitable for indoor and light outdoor applications
• ✅ No hydrogen embrittlement risk at standard hardness levels

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DIN 7349 vs. DIN 125 — Key Differences

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

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Application Scenarios

• Heavy machinery & structural assemblies with bolts using heavy-type spring pins (DIN 7346)
• Industrial equipment requiring large bearing surface to prevent pull-through under high loads
• Automotive manufacturing — body panels, chassis, and suspension assemblies
• Construction & steel structures — indoor and sheltered outdoor environments
• HVAC & mechanical systems — ductwork, equipment mounting, vibration-prone assemblies
• Electronics enclosures & control panels — where RoHS compliance is mandatory
• General light industrial — wherever a heavy-type washer with corrosion protection is required

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Product Photo Gallery

Real product images — FULLERKREG DIN 7349 Thick Flat Washer, Steel Zinc CR3:

[ Photo 1 ]

[ Photo 2 ]

[ Photo 3 ]

[ Photo 4 ]

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Packaging & Supply

Size	Standard Pack (pcs)	Bulk Carton (pcs)	Weight per 100 pcs (approx.)
M5	100	5,000	~107 g
M6	100	3,000	~201 g
M8	50	2,000	~465 g
M10	50	1,000	~977 g
M12	25	500	~1,974 g
M16	25	200	~5,452 g
M20	10	100	~11,660 g
M24	10	50	~19,370 g

Custom packaging and labeling available for OEM / wholesale orders. Contact FULLERKREG for bulk pricing.

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Why Choose FULLERKREG?

• 🏭 Direct manufacturer — factory in China, no middlemen
• 📐 Strict DIN dimensional control — 100% inspection on critical dimensions
• 🌍 Global export experience — serving distributors in Europe, North America, Southeast Asia
• 📦 Flexible MOQ — small trial orders and large bulk shipments both welcome
• 📋 Full documentation — material certs, RoHS declarations, test reports available
• ⚡ Fast lead times — standard sizes in stock, ready to ship

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Frequently Asked Questions

Q: What is DIN 7349 and how does it differ from DIN 125?
A: DIN 7349 is a thick flat washer standard 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: What is Zinc CR3 and why is it preferred over traditional zinc plating?
A: Zinc CR3 uses trivalent chromium (Cr3+) passivation instead of the traditional hexavalent chromium (Cr6+). It is fully RoHS and ELV compliant, provides equivalent or better corrosion protection (≥72h salt spray), and eliminates the environmental and health risks associated with Cr6+ coatings.

Q: Is Zinc CR3 suitable for outdoor use?
A: Zinc CR3 is suitable for indoor and light outdoor (sheltered) environments. For prolonged outdoor exposure, coastal, or high-humidity environments, stainless steel grades (A2 or A4) are recommended.

Q: Are these washers RoHS compliant?
A: Yes. FULLERKREG Zinc CR3 washers use trivalent chromium passivation only — no hexavalent chromium (Cr6+). Full RoHS and REACH compliance documentation is available upon request.

Q: Can I order mixed sizes in one shipment?
A: Yes. FULLERKREG supports mixed-size wholesale orders. Please contact us with your size breakdown and quantities for a custom quotation.

Q: Do you provide material test certificates?
A: Yes. Mill certificates, dimensional inspection reports, and surface treatment test reports are available for all orders upon request.

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For wholesale inquiries, technical questions, or custom orders, please contact our sales team.