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FULLERKREG DIN 6797J internal tooth lock washers are manufactured to DIN 6797 Form J standard in 65Mn high-manganese spring steel (per GB/T 1222) with zinc electroplating and trivalent chromium (CR3) passivation. DIN 6797 Form J features internal teeth on the inner diameter with a deeper, more aggressive tooth profile than DIN 6798J, providing strong mechanical anti-loosening engagement while preserving the outer substrate surface. 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 6797 Form J.
| 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 J. d1 = inner diameter; d2 = outer 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 | 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 |
| Feature | Form J (Internal) — This Product | Form A (External) |
|---|---|---|
| Tooth 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 — largest tooth radius |
| Best for | Visible / finished surfaces | Maximum anti-loosening performance |
FULLERKREG DIN 6797J Internal Tooth Lock Washer, 65Mn Spring Steel, Zinc CR3:
| [ Photo 1 ] | [ Photo 2 ] | [ Photo 3 ] | [ Photo 4 ] |
Q: What is DIN 6797 Form J?
A: DIN 6797 Form J is an internal tooth lock washer (shakeproof washer). The teeth are on the inner diameter with a deeper, more aggressive profile than DIN 6798J. They bite into the fastener shank or bolt head underside, providing strong mechanical anti-loosening without marking the outer substrate surface.
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: Form J vs. Form A — which to choose?
A: Form J (internal) preserves the outer substrate surface — best when outer appearance must be maintained. Form A (external) maximizes anti-loosening torque by acting at the largest radius — best for maximum performance.
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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