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FULLERKREG ISO 7380-2 Grade 10.9 Zinc CR3 Flanged Button Head Socket Cap Screws are high-strength fasteners featuring a low-profile dome-shaped button head with an integrated flange and a hexagon socket drive. Manufactured from 10B21 boron-alloyed steel with an electroplated zinc CR3 (trivalent chromate) surface treatment, these screws combine Grade 10.9 tensile strength (min. 1,040 MPa) with the engineering advantages of an integrated flange, reliable corrosion resistance, and full RoHS environmental compliance. The bright silver zinc finish provides a professional appearance while the flange eliminates the need for a separate washer in most applications.
| Property | ISO 7380-2 Flanged (This Page) | ISO 7380-1 Plain Button Head |
|---|---|---|
| Head profile | Low dome + integrated flange | Low dome only |
| Bearing surface area | Significantly larger (flange) | Standard button head |
| Washer required? | No — flange acts as integrated washer | Sometimes yes |
| Pull-through resistance | Superior | Standard |
| Load distribution | Excellent on thin/soft materials | Good |
| Assembly efficiency | Faster — one fewer component | Standard |
| Best for | Thin panels, soft materials, high pull-through risk | General low-profile applications |
The zinc CR3 coating uses trivalent chromium (Cr3+) passivation, replacing the traditional hexavalent chromium (Cr6+) process. This is essential for compliance with international environmental regulations:
| Regulation | Requirement | CR3 Zinc Compliance |
|---|---|---|
| EU RoHS Directive (2011/65/EU) | No hexavalent chromium (Cr6+) | ✅ Compliant |
| EU REACH Regulation | No SVHC restricted substances | ✅ Compliant |
| ELV Directive (2000/53/EC) | No Cr6+ in vehicle components | ✅ Compliant |
| China RoHS (GB/T 26572) | No restricted hazardous substances | ✅ Compliant |
| Property | Zinc CR3 (This Page) | Black Oxide |
|---|---|---|
| Appearance | Bright silver | Matte black |
| Coating thickness | 5–12 μm | 1–2 μm |
| Salt spray resistance | 24–48 hrs | Low (without oil) |
| RoHS compliance | ✅ Compliant (CR3) | ✅ Compliant |
| Best for | Outdoor, humid, RoHS-regulated applications | Indoor, general industrial |
| Price | 🔵 Slightly higher | 🟢 Economy |
FULLERKREG ISO 7380-2 Grade 10.9 Zinc CR3 flanged button head screws are manufactured from 10B21 boron-alloyed steel. The addition of boron (B) significantly improves hardenability, enabling Grade 10.9 mechanical properties with a leaner alloy composition. All values are maximum unless a range is indicated.
| Grade | C | Si (max) | Mn | P (max) | S (max) | B |
|---|---|---|---|---|---|---|
| 10B21 | 0.18–0.23 | ≤0.30 | 0.80–1.10 | ≤0.030 | ≤0.030 | 0.0005–0.003 |
| Property | Requirement | Unit |
|---|---|---|
| Tensile Strength (Rm) | Min. 1,040 | MPa |
| Yield Strength / Proof Load Stress (Rp0.2) | Min. 940 | MPa |
| Core Hardness | 32–39 | HRC |
| Surface Hardness (max) | ≤44 | HRC |
| Elongation after fracture (A) | Min. 9 | % |
| Reduction of area (Z) | Min. 48 | % |
| Impact energy (KV) at room temp. | Min. 37 | J |
| Thread Tolerance Class | 6g | — |
| Surface Treatment | Zinc CR3 (trivalent chromate) | — |
FULLERKREG ISO 7380-2 Grade 10.9 Zinc CR3 flanged button head socket cap screws are widely used in high-strength, RoHS-regulated, and corrosion-exposed applications:
Key dimensions per ISO 7380-2 (2022). The flange diameter (dc) is the critical additional dimension vs. ISO 7380-1.
| Thread (d) | Pitch (p) | Head Dia. dk Max. | Head Dia. dk Min. | Flange Dia. dc Max. | Flange Dia. dc Min. | Head Height k Max. | Head Height k Min. | Key Size s | Key Depth t Min. |
|---|---|---|---|---|---|---|---|---|---|
| M4 | 0.7 | 7.60 | 7.36 | 9.40 | 9.00 | 2.20 | 1.80 | 2.5 | 1.05 |
| M5 | 0.8 | 9.50 | 9.22 | 11.80 | 11.40 | 2.75 | 2.25 | 3.0 | 1.35 |
| M6 | 1.0 | 10.50 | 10.22 | 13.60 | 13.20 | 3.30 | 2.70 | 4.0 | 1.60 |
| M8 | 1.25 | 14.00 | 13.57 | 17.90 | 17.50 | 4.40 | 3.60 | 5.0 | 2.20 |
| M10 | 1.5 | 17.50 | 17.05 | 22.30 | 21.80 | 5.50 | 4.50 | 6.0 | 2.75 |
| M12 | 1.75 | 21.00 | 20.48 | 26.70 | 26.20 | 6.60 | 5.40 | 8.0 | 3.30 |
| M16 | 2.0 | 28.00 | 27.48 | 35.70 | 35.20 | 8.80 | 7.20 | 10.0 | 4.40 |
Q: What is the difference between ISO 7380-1 and ISO 7380-2?
ISO 7380-1 is the plain button head socket cap screw with no flange. ISO 7380-2 adds an integrated flange under the button head, which significantly increases the bearing surface area, acts as a built-in washer, and provides superior pull-through resistance.
Q: What is the difference between Zinc CR3 and traditional yellow zinc (Cr6+)?
Traditional yellow zinc chromate uses hexavalent chromium (Cr6+), which is restricted under EU RoHS and REACH regulations. Zinc CR3 uses trivalent chromium (Cr3+), providing equivalent corrosion protection without any restricted substances. CR3 is the environmentally compliant replacement.
Q: Do I still need a washer with ISO 7380-2 flanged button head screws?
In most applications, no. The integrated flange provides sufficient bearing area to replace a standard flat washer, reducing part count and assembly time.
Q: Can Grade 10.9 flanged button head screws handle the same torque as Grade 10.9 socket cap screws?
No. Due to the shallower socket depth in the button head design, the maximum recommended tightening torque is lower than for standard socket cap screws (DIN 912) of the same grade. Always use ISO 7380-2 specific torque values.
Q: Can I get RoHS compliance documentation and material certificates?
Yes. FULLERKREG provides RoHS compliance declarations, PPAP reports, material certificates, hardness test reports, and tensile test reports upon request.
All FULLERKREG ISO 7380-2 Grade 10.9 Zinc CR3 flanged button head socket cap screws are manufactured under strict quality control procedures including:
For wholesale pricing, bulk orders, RoHS documentation, or technical inquiries, please contact our sales team.
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