Socket Head Cap Screws

Socket Head Cap Screws DIN 912 — Allen Head Screws | M3–M24 | High Strength Precision Fasteners

Socket head cap screws manufactured to DIN 912 (ISO 4762) feature a cylindrical head with an internal hex (Allen) drive socket. These precision fasteners are designed for applications requiring high clamping force in restricted-access spaces where external hex heads cannot be used. Available in M3 to M24 sizes with Grade 12.9 strength as standard, our socket head cap screws are the preferred choice for machinery, tooling, and precision equipment assembly.

Material & Specifications

Size Range	M3 to M24 / #4 to 1″
Standard	DIN 912, ISO 4762, ANSI B18.3
Material	Alloy Steel (Grade 12.9 standard), 304 SS (A2-70), 316 SS (A4-80)
Surface / Coating	Black Oxide (standard), Dacromet, Zinc Plated, Phosphating, Plain
Tensile Strength	≥ 1220 MPa (Grade 12.9)
Head Diameter	1.5x thread diameter (nominal)

Surface Treatment & Zinc Coating Quality

At BoltNutsPlus, we understand that surface treatment is critical to fastener longevity and performance. Our products undergo rigorous coating processes to ensure maximum corrosion resistance and durability. We offer five premium coating options, each tested to international standards:

• Hot-Dip Galvanizing (HDG) — Thick zinc layer (50-120μm) providing superior long-term corrosion protection for outdoor, marine, and industrial environments. Compliant with ISO 1461 / ASTM A153 standards. Salt spray resistance: 500-1,000+ hours. Ideal for structural steel assemblies exposed to harsh weather.
• Electroplated Zinc Blue-White (Zn Blue/White) — Bright, clean silver-blue appearance with 5-15μm zinc layer. Cr3+ passivation technology, fully RoHS compliant. Ideal for indoor machinery, electronics, and general-purpose applications requiring aesthetic appeal and moderate corrosion resistance.
• Color Zinc / Yellow Zinc (Iridescent Passivation) — Multi-colored iridescent passivation film offering enhanced corrosion resistance (100-200 hours salt spray) with a distinctive golden finish. Widely preferred in automotive, agricultural equipment, and construction machinery sectors for its balanced protection and visual appeal.
• Dacromet Coating — Advanced water-based zinc-chromium coating technology with NO hydrogen embrittlement risk. Provides 1,000+ hours salt spray resistance, making it the preferred choice for high-strength fasteners in extreme environments. Environmentally friendly (no heavy metal discharge), RoHS/ELV compliant, ideal for automotive and wind energy applications.
• Multi-Element Alloy Co-Permeation — Zinc-aluminum-rare earth alloy layer offering 2-3x the corrosion resistance of traditional galvanizing. Features self-healing properties at scratch points, ensuring long-term protection even in damaged areas. Ideal for critical infrastructure, power transmission towers, coastal projects, and marine installations.

Key Features

• Cylindrical head design allows access in tight spaces with Allen wrench
• Grade 12.9 alloy steel provides maximum clamping force per size
• Precision-rolled threads for consistent torque-tension relationship
• Black oxide finish provides mild corrosion resistance and professional appearance
• Full and partial thread options available for different grip lengths
• Full traceability with material certificates (EN 10204 3.1)

Applications

• Machinery and equipment assembly requiring precision fastening
• Mold, die, and tooling applications
• Hydraulic and pneumatic cylinder end cap connections
• Automotive engine and transmission components
• Aerospace and defense equipment (with special certification)
• Robotics and automation system assembly

Why Choose BoltNutsPlus?

• ISO 9001:2015 Certified Manufacturing — consistent quality you can trust on every batch
• 15+ Years of Export Experience — serving 40+ countries across 6 continents
• Full Traceability — material certificates (EN 10204 3.1) and comprehensive test reports included
• Custom Packaging & OEM/ODM — your brand identity, your specifications, our precision manufacturing
• Third-Party SGS / Bureau Veritas Inspection Available upon request
• 24-Hour Quote Response — same-day reply for urgent requirements; standard 24-hour turnaround