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DIN 6798J Zinc Internal Serrated Lock

DIN 6798J Internal Serrated Lock Washer — 65Mn Spring Steel, Zinc Plated CR3

FULLERKREG DIN 6798J internal serrated lock washers are manufactured to DIN 6798 Form J standard in 65Mn high-manganese spring steel (per GB/T 1222) with zinc electroplating and trivalent chromium (CR3) passivation. DIN 6798 Form J features internal serrations (teeth on the inner diameter) that bite into the fastener shank or bolt head bearing surface, providing positive anti-loosening performance through mechanical engagement while preserving the outer substrate surface. 65Mn spring steel achieves 430–510 HV hardness after quench and temper, delivering superior tooth sharpness retention and fatigue resistance. The zinc CR3 finish provides ≥72h salt spray resistance with full RoHS compliance.

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.

Product Highlights

  • Standard: DIN 6798 Form J (Internal Serrated Lock Washer)
  • 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
  • Serration type: Internal (teeth on inner diameter — bite into fastener shank)
  • Outer surface preserved — no marking on substrate outer surface
  • RoHS Compliant — CR3, no Cr6+
  • Post-plate baking — hydrogen embrittlement relief per ISO 9587

Dimensional Specifications — DIN 6798 Form J (Internal Serrated), 65Mn Steel Zinc CR3

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

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 J. d1 = inner diameter; d2 = outer diameter; d3 = serration root diameter; s = thickness.

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+

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

DIN 6798 Form J vs. Form A — Key Differences

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

Application Scenarios

  • Visible or finished surfaces — internal teeth preserve outer substrate appearance
  • Heavy machinery & industrial equipment — high hardness teeth, outdoor corrosion protection
  • Automotive manufacturing — chassis and body assemblies exposed to moisture
  • Construction & steel structures — sheltered outdoor environments
  • Agricultural & mining equipment — high-vibration, humid conditions
  • Electrical enclosures & control panels — reliable anti-loosening with corrosion protection
  • General bolted assemblies — where RoHS-compliant zinc finish is required

Product Photo Gallery

FULLERKREG DIN 6798J Internal Serrated Lock Washer, 65Mn Spring Steel, Zinc CR3:

[ Photo 1 ] [ Photo 2 ] [ Photo 3 ] [ Photo 4 ]

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

Frequently Asked Questions

Q: What is DIN 6798 Form J?
A: DIN 6798 Form J is an internal serrated lock washer. The teeth are on the inner diameter and bite into the fastener shank or bolt head underside when tightened, providing mechanical anti-loosening without marking the outer substrate surface.

Q: Why 65Mn spring steel for serrated lock washers?
A: 65Mn achieves 430–510 HV after quench and temper, providing sharp, durable teeth that maintain their bite-in performance under repeated loading. Higher hardness than standard carbon steel ensures the 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 and spring properties.

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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