DIN 6798A External Serrated Lock Washer — A4 Marine Stainless Steel (SUS316), Whitened & Passivated

FULLERKREG DIN 6798A external serrated lock washers are manufactured to DIN 6798 Form A standard in A4 marine stainless steel (SUS316 / 1.4401 / 06Cr17Ni12Mo2) with a whitened and passivated surface finish. DIN 6798 Form A features external serrations (teeth on the outer diameter) that bite into the substrate surface under the bolt head or nut, providing positive anti-loosening performance through mechanical engagement. A4 stainless steel contains 2–3% molybdenum, providing superior resistance to chloride corrosion, seawater, and acidic environments — the correct choice for marine, offshore, and coastal applications where A2 (SUS304) may suffer pitting corrosion.

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Product Highlights

• Standard: DIN 6798 Form A (External Serrated Lock Washer)
• Material: A4 Marine Stainless Steel (SUS316 / 1.4401 / 06Cr17Ni12Mo2)
• Surface Treatment: Whitened & Passivated
• Size Range: M3 – M30
• Serration type: External (teeth on outer diameter — bite into substrate surface)
• Molybdenum content: 2–3% — superior chloride & seawater resistance vs. A2
• Anti-loosening mechanism: Mechanical tooth engagement — resists rotation under vibration
• Non-magnetic, non-sparking
• RoHS & REACH Compliant

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Dimensional Specifications — DIN 6798 Form A (External Serrated), A4 Stainless

All dimensions in millimeters (mm). Per DIN 6798 Form A.

For Thread	Nominal Size	d1 min	d1 max	d2 Nominal	d3 approx.	Min. No. of Teeth	s min	s max	kg/1000pcs
M3	3	3.2	3.5	6.5	5.3	9	0.3	0.4	0.025
M3.5	3.5	3.7	4.0	7.5	6.0	9	0.3	0.4	0.04
M4	4	4.3	4.6	8.0	6.5	11	0.4	0.5	0.06
M5	5	5.3	5.6	9.5	7.7	11	0.5	0.6	0.1
M6	6	6.4	6.8	11.5	9.3	14	0.5	0.6	0.17
M7	7	7.4	7.8	13.0	10.5	14	0.5	0.6	0.24
M8	8	8.4	8.8	15.0	12.1	14	0.6	0.8	0.38
M10	10	10.5	11.0	18.0	14.6	16	0.8	1.0	0.7
M12	12	13.0	13.5	21.0	17.0	18	0.8	1.0	0.9
M14	14	15.0	15.5	24.0	19.5	18	0.8	1.0	1.2
M16	16	17.0	17.5	27.0	21.9	18	1.0	1.2	1.9
M18	18	19.0	19.5	30.0	24.4	18	1.0	1.2	2.3
M20	20	21.0	21.5	33.0	26.8	20	1.0	1.2	3.0
M22	22	23.0	23.5	36.0	29.3	20	1.0	1.2	3.7
M24	24	25.0	25.5	39.0	31.7	20	1.2	1.5	5.5
M27	27	28.0	28.5	44.0	35.8	20	1.2	1.5	7.0
M30	30	31.0	31.5	47.0	38.2	20	1.2	1.5	8.0

All dimensions in mm per DIN 6798 Form A. d1 = inner diameter; d2 = outer diameter; d3 = serration root diameter; s = thickness. Same dimensions as A2 grade — material and corrosion resistance differ.

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A4 vs. A2 Stainless Steel — Key Differences

Property	A4 (SUS316) — This Product	A2 (SUS304)
Molybdenum (Mo)	2.0 – 3.0%	None
Chloride resistance	Superior — marine grade	Good — general use
Seawater resistance	Excellent	Limited
Acid resistance	Better (Mo addition)	Standard
Typical use	Marine, offshore, coastal, chemical	General outdoor, food, fresh water

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DIN 6798 Form A vs. Form J vs. Form V — Key Differences

Feature	Form A (External)	Form J (Internal)	Form V (Countersunk)
Serration location	Outer diameter	Inner diameter	Outer diameter, countersunk
Bites into	Substrate surface	Fastener shank / bolt	Substrate surface (countersunk)
Contact area	Maximum — larger tooth radius	Standard	Standard
Typical use	General anti-loosening, most common	Outer appearance must be preserved	Countersunk screw assemblies

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Material & Mechanical Properties — A4 Marine Stainless Steel (SUS316)

Property	Value
Material Grade	A4 / SUS316 / 1.4401 / 06Cr17Ni12Mo2
Cr Content	16.0 – 18.0%
Ni Content	10.0 – 14.0%
Mo Content	2.0 – 3.0%
Surface Treatment	Whitened & Passivated
Magnetic	Non-magnetic (austenitic)
Operating Temperature	-196°C to +300°C
Corrosion Resistance	Excellent — seawater, chlorides, acids, marine environments
RoHS / REACH	Compliant

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Application Scenarios

• Marine & offshore structures — seawater splash zones, boat fittings, dock hardware
• Coastal construction — salt air environments, bridges, coastal infrastructure
• Chemical processing equipment — resistance to acids and chloride-containing media
• Food & beverage processing — hygienic, easy to clean, non-toxic
• Swimming pools & water treatment — chlorinated water resistance
• Automotive & transportation — vibration resistance in harsh corrosive environments
• General industrial bolted assemblies — where marine-grade corrosion resistance is required

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Product Photo Gallery

FULLERKREG DIN 6798A External Serrated Lock Washer, A4 Marine Stainless Steel:

[ Photo 1 ]

[ Photo 2 ]

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[ Photo 4 ]

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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: Why choose A4 over A2 for serrated lock washers?
A: A4 (SUS316) contains 2–3% molybdenum which significantly improves resistance to chloride pitting and crevice corrosion. In marine, coastal, or chloride-rich environments where A2 (SUS304) may suffer pitting, A4 is the correct choice.

Q: What is DIN 6798 Form A?
A: DIN 6798 Form A is an external serrated lock washer. The teeth are on the outer diameter and bite into the substrate surface under the bolt head or nut, providing mechanical anti-loosening. It is the most common type for general industrial use.

Q: Form A vs. Form J — which to choose?
A: Form A (external) maximizes anti-loosening torque by acting at the largest radius. Form J (internal) preserves the outer substrate surface. Choose Form A for maximum performance; Form J when outer appearance must be maintained.

Q: Do you provide material test certificates?
A: Yes. Mill certificates, chemical composition reports, and dimensional inspection reports are available upon request.

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