ISO 7380 Button Head Socket Cap Screw Grade 10.9 Zinc CR3

FULLERKREG ISO 7380-1 / GB70.2 Grade 10.9 Zinc CR3 Button Head Socket Cap Screws

FULLERKREG ISO 7380-1 / GB70.2 Grade 10.9 Zinc CR3 Button Head Socket Cap Screws are high-strength fasteners featuring a low-profile dome-shaped button head with a hexagon socket drive. Manufactured from 10B21 boron-alloyed steel with an electroplated zinc coating using CR3 trivalent chromate passivation, these screws combine Grade 10.9 tensile strength (min. 1,040 MPa) with superior corrosion resistance and full RoHS environmental compliance. The bright silver zinc finish provides a professional appearance while protecting against corrosion in demanding environments.

Product Specifications

• Standards: ISO 7380-1 / GB 70.2
• Strength Grade: 10.9 (heat treated)
• Material: 10B21 boron-alloyed steel
• Tensile Strength: Min. 1,040 MPa
• Yield Strength: Min. 940 MPa
• Hardness: HRC 32–39
• Head Type: Button head (low-profile dome)
• Surface Treatment: Zinc electroplating with CR3 trivalent chromate passivation
• Plating Thickness: Typically 5–12 μm zinc
• RoHS Compliance: ✅ Fully compliant — CR3 trivalent chromate contains no hexavalent chromium (Cr6+)
• Thread Type: Metric coarse, full thread
• Thread Tolerance: 6g
• Drive Type: Hexagon socket (Allen key / hex key)
• Sizes Available: M3 – M16

RoHS Compliance — CR3 Trivalent Chromate Zinc Plating

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

Surface Finish Comparison — Zinc CR3 vs Black Oxide

Property	Zinc CR3 (This Page)	Black Oxide
Appearance	Bright silver	Matte black
Coating thickness	5–12 μm	1–2 μm
Corrosion resistance	Good (72–120 hrs salt spray)	Moderate (with oil)
RoHS compliance	✅ Compliant (CR3)	✅ Compliant
Best for	Outdoor, humid, RoHS-regulated applications	Indoor, precision, aesthetic applications
Price	🔵 Slightly higher	🟢 Economy

Material — 10B21 Boron Steel Chemical Composition (%)

FULLERKREG ISO 7380-1 Grade 10.9 Zinc CR3 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

Mechanical Properties — Grade 10.9 (ISO 898-1)

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)	—

Key Features

• ✅ RoHS & REACH Compliant — CR3 trivalent chromate zinc plating contains no hexavalent chromium (Cr6+), meeting EU RoHS, REACH, ELV, and China RoHS requirements
• Grade 10.9 high strength — 1,040 MPa tensile strength in a compact button head profile
• Low-profile button head — smooth dome design, approximately 50% lower than standard socket cap screws (DIN 912)
• Zinc CR3 coating — bright silver appearance with 72–120 hours salt spray resistance, superior to black oxide
• Wide bearing surface — larger head diameter distributes clamping load over a greater area
• 10B21 boron steel — excellent hardenability and consistent mechanical properties through heat treatment
• ISO 7380-1 / GB 70.2 dual standard — suitable for both international and Chinese domestic supply chains
• ISO/TS16949 quality management — hardness test, tensile test, salt spray test, and PPAP report available on request

Applications

FULLERKREG ISO 7380-1 Grade 10.9 Zinc CR3 button head socket cap screws are widely used in high-strength, RoHS-regulated, and corrosion-exposed applications:

• Electronics and electrical equipment (EU RoHS regulated)
• Automotive components and EV (electric vehicle) assemblies (ELV compliant)
• Robotics and automation equipment in humid or outdoor environments
• Consumer electronics and home appliances
• Outdoor machinery and equipment requiring corrosion-resistant fasteners
• Bicycle frames, motorcycle components, and sporting equipment
• Industrial fixtures requiring high strength and corrosion protection
• Any application requiring Grade 10.9 button head screws with RoHS-compliant zinc plating

Dimensional Specifications — ISO 7380-1 (Unit: mm)

Thread (d)	Pitch (p)	Head Dia. dk Max.	Head Dia. dk Min.	Head Height k Max.	Head Height k Min.	Key Size s	Key Depth t Min.	Body Dia. ds Max.	Body Dia. ds Min.
M3	0.5	5.70	5.50	1.65	1.35	2.0	0.74	3.00	2.86
M4	0.7	7.60	7.36	2.20	1.80	2.5	1.05	4.00	3.82
M5	0.8	9.50	9.22	2.75	2.25	3.0	1.35	5.00	4.82
M6	1.0	10.50	10.22	3.30	2.70	4.0	1.60	6.00	5.82
M8	1.25	14.00	13.57	4.40	3.60	5.0	2.20	8.00	7.78
M10	1.5	17.50	17.05	5.50	4.50	6.0	2.75	10.00	9.78
M12	1.75	21.00	20.48	6.60	5.40	8.0	3.30	12.00	11.73
M16	2.0	28.00	27.48	8.80	7.20	10.0	4.40	16.00	15.73

Frequently Asked Questions

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 or better corrosion protection without any restricted substances. CR3 is the environmentally compliant replacement.

Q: Can Grade 10.9 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 7380-1 specific torque values.

Q: What is GB 70.2?
GB 70.2 is the Chinese national standard for button head socket cap screws, equivalent to ISO 7380-1. These screws comply with both standards and are interchangeable in most applications.

Q: Can I get RoHS compliance documentation?
Yes. FULLERKREG provides RoHS compliance declarations, material certificates, and test reports upon request for all zinc CR3 plated products.

Q: What corrosion resistance does Zinc CR3 provide?
Zinc CR3 plating typically provides 72–120 hours of salt spray resistance (per ISO 9227) before red rust appears, depending on plating thickness. This is significantly better than black oxide.

Packaging & Availability

• Standard sizes M3 – M16 available in stock
• Bulk carton packaging; small box and custom packaging available
• RoHS compliance documentation and material certificates available on request
• PPAP report and test reports available on request
• Custom lengths accepted for large orders

Download Specification

• ISO 7380-1 — Full Dimensional Specification (PDF)
• ISO 898-1 — Mechanical Properties of Fasteners (PDF)

Quality Assurance

All FULLERKREG ISO 7380-1 Grade 10.9 Zinc CR3 button head socket cap screws are manufactured under strict quality control procedures including:

• Rockwell hardness test (HRC 32–39)
• Tensile strength test (min. 1,040 MPa)
• Salt spray corrosion test (zinc CR3 plating)
• RoHS substance verification — no hexavalent chromium (Cr6+)
• Dimensional inspection per ISO 7380-1
• Chemical composition analysis (10B21, B content verified)
• PPAP documentation available upon request

For wholesale pricing, bulk orders, RoHS documentation, or technical inquiries, please contact our sales team.