DIN 6797A External Tooth Lock Washer (Shakeproof) — 65Mn Spring Steel, Zinc Plated CR3

FULLERKREG DIN 6797A external tooth lock washers are manufactured to DIN 6797 Form A standard in 65Mn high-manganese spring steel (per GB/T 1222) with zinc electroplating and trivalent chromium (CR3) passivation. DIN 6797 Form A features external teeth on the outer diameter with a deeper, more aggressive tooth profile than DIN 6798A, providing maximum anti-loosening performance through mechanical engagement at the largest possible tooth radius. 65Mn spring steel achieves 430–510 HV hardness after quench and temper, delivering sharp, durable teeth with superior fatigue resistance. The zinc CR3 finish provides ≥72h salt spray resistance with full RoHS compliance. This combination of deep-profile external teeth and high-hardness spring steel delivers the strongest anti-loosening performance in the DIN 6797 range.

Note on hydrogen embrittlement: At 430–510 HV, electroplating introduces hydrogen embrittlement risk. FULLERKREG applies mandatory post-plate baking (per ISO 9587 / GB/T 13912) to eliminate this risk and ensure tooth integrity.

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Product Highlights

• Standard: DIN 6797 Form A (External Tooth Lock Washer / Shakeproof)
• Material: 65Mn Spring Steel (GB/T 1222)
• Surface Treatment: Zinc Electroplating + CR3 Trivalent Chromium Passivation
• Corrosion Resistance: ≥72h neutral salt spray (NSS) per ISO 9227
• Hardness: 430–510 HV (approx. 44–50 HRC) after quench & temper
• Size Range: M3 – M30
• Tooth type: External (teeth on outer diameter — deeper profile than DIN 6798A)
• Maximum anti-loosening torque — deep teeth at largest radius + high hardness
• RoHS Compliant — CR3, no Cr6+
• Post-plate baking — hydrogen embrittlement relief per ISO 9587

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Dimensional Specifications — DIN 6797 Form A (External Tooth), 65Mn Steel Zinc CR3

All dimensions in millimeters (mm). Per DIN 6797 Form A.

For Thread	d1 min	d1 max	d2 max	No. of Teeth	s min	s max	kg/1000pcs
M3	3.2	3.5	7.0	12	0.4	0.6	0.07
M3.5	3.7	4.0	8.0	12	0.4	0.6	0.1
M4	4.3	4.6	9.0	16	0.5	0.7	0.15
M5	5.3	5.6	10.0	16	0.5	0.7	0.18
M6	6.4	6.8	12.0	20	0.6	0.8	0.28
M7	7.4	7.8	14.0	20	0.6	0.8	0.42
M8	8.4	8.8	16.0	20	0.8	1.0	0.7
M10	10.5	11.0	20.0	24	0.8	1.0	1.1
M12	13.0	13.5	24.0	24	1.0	1.3	2.0
M14	15.0	15.5	27.0	24	1.0	1.3	2.6
M16	17.0	17.5	30.0	24	1.2	1.5	3.8
M18	19.0	19.5	34.0	28	1.2	1.5	5.1
M20	21.0	21.5	37.0	28	1.2	1.5	6.1
M22	23.0	23.5	39.0	28	1.5	1.8	7.5
M24	25.0	25.5	44.0	28	1.5	1.8	10.0
M27	28.0	28.5	50.0	32	1.5	1.8	14.0
M30	31.0	31.5	56.0	32	1.5	1.8	19.0

All dimensions in mm per DIN 6797 Form A. d1 = inner diameter; d2 = outer diameter; s = thickness.

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Material Properties — 65Mn Spring Steel (GB/T 1222)

Property	Value
Material Grade	65Mn Spring Steel
GB Standard	GB/T 1222, GB/T 4354
C Content	0.62 – 0.70%
Mn Content	0.90 – 1.20%
Heat Treatment	Quench & Temper
Hardness	430–510 HV (approx. 44–50 HRC)
Tensile Strength	1275 MPa min.
Surface Treatment	Zinc Electroplating + CR3 Passivation
Salt Spray Resistance	≥72h NSS per ISO 9227
H2 Embrittlement Relief	Post-plate baking per ISO 9587 / GB/T 13912
Operating Temperature	-40°C to +120°C
RoHS / REACH	Compliant — CR3, no Cr6+

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Chemical Composition — 65Mn Spring Steel (GB/T 1222)

Element	C	Mn	Si	P max	S max	Cr max	Ni max
Content %	0.62–0.70	0.90–1.20	0.17–0.37	0.035	0.035	0.25	0.25

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DIN 6797 vs. DIN 6798 — Key Differences

Feature	DIN 6797 (Shakeproof)	DIN 6798 (Serrated)
Tooth profile	Deeper, more aggressive	Shallower, standard serration
Anti-loosening strength	Stronger — higher bite-in force	Standard
Typical use	Electrical, automotive, high-vibration	General industrial assemblies
Common name	Shakeproof washer	Serrated lock washer

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DIN 6797 Form A vs. Form J — Key Differences

Feature	Form A (External) — This Product	Form J (Internal)
Tooth location	Outer diameter	Inner diameter
Bites into	Substrate surface	Fastener shank / bolt head
Outer surface	Marked by teeth	Preserved — no marking
Anti-loosening torque	Maximum — largest tooth radius	Standard
Best for	Maximum anti-loosening performance	Visible / finished surfaces

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Application Scenarios

• Heavy machinery & industrial equipment — maximum anti-loosening + outdoor corrosion protection
• Automotive manufacturing — chassis, underbody, and engine assemblies exposed to moisture
• Electrical & electronics assemblies — shakeproof design for high-vibration electrical equipment
• Construction & steel structures — sheltered outdoor environments
• Agricultural & mining equipment — high-vibration, humid conditions
• Railway & transportation equipment — vibration resistance with corrosion protection
• General industrial bolted assemblies — RoHS-compliant zinc finish, maximum performance

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Product Photo Gallery

FULLERKREG DIN 6797A External Tooth Lock Washer, 65Mn Spring Steel, Zinc CR3:

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Why Choose FULLERKREG?

• 🏭 Direct manufacturer — factory in China, no middlemen
• 📐 Strict DIN dimensional control — 100% inspection on critical dimensions and hardness
• 🌍 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, hardness reports, salt spray reports, RoHS declarations
• ⚡ Fast lead times — standard sizes in stock, ready to ship

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Frequently Asked Questions

Q: What is DIN 6797 Form A?
A: DIN 6797 Form A is an external tooth lock washer (shakeproof washer). The teeth are on the outer diameter with a deeper, more aggressive profile than DIN 6798A. They bite into the substrate surface under the bolt head or nut, providing maximum mechanical anti-loosening at the largest possible tooth radius.

Q: Why 65Mn spring steel for shakeproof washers?
A: 65Mn achieves 430–510 HV after quench and temper, providing sharp, durable teeth that maintain bite-in performance under repeated loading and vibration. Higher hardness ensures teeth do not deform under tightening torque.

Q: What is CR3 passivation?
A: CR3 refers to trivalent chromium passivation over zinc electroplating. Provides ≥72h NSS corrosion protection without Cr6+. Fully RoHS compliant.

Q: How is hydrogen embrittlement managed?
A: Post-plate baking at 190–220°C for 4–8 hours per ISO 9587 drives off absorbed hydrogen before the zinc coating seals, restoring tooth integrity.

Q: Do you provide material test certificates?
A: Yes. Mill certificates, hardness reports, salt spray reports, and RoHS declarations available upon request.

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