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FULLERKREG DIN 6798A external serrated lock washers are manufactured to DIN 6798 Form A standard in 65Mn high-manganese spring steel (per GB/T 1222) with zinc electroplating and trivalent chromium (CR3) passivation. 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 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.
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.
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.
| 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+ |
| 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 |
| Feature | Form A (External) — This Product | Form J (Internal) |
|---|---|---|
| Serration 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 (larger radius) | Standard |
| Best for | General industrial assemblies, maximum performance | Visible / finished surfaces |
FULLERKREG DIN 6798A External Serrated Lock Washer, 65Mn Spring Steel, Zinc CR3:
| [ Photo 1 ] | [ Photo 2 ] | [ Photo 3 ] | [ Photo 4 ] |
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 maximum mechanical anti-loosening at the largest possible tooth radius. The most common type for general industrial use.
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 bite-in performance under repeated loading. Higher hardness than standard carbon steel 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: Form A vs. Form J — which to choose?
A: Form A (external) maximizes anti-loosening torque by acting at the largest radius — best for general industrial assemblies. Form J (internal) preserves the outer substrate surface — best when outer appearance must be maintained.
Q: Do you provide material test certificates?
A: Yes. Mill certificates, hardness reports, salt spray reports, and RoHS declarations available upon request.
FULLERKREG Fasteners — Precision DIN Standard Fasteners, Direct from Manufacturer.
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