Half Thread Hex Bolts

Half Thread Hex Bolts — DIN 931 / ISO 4014 | Partially Threaded Hexagon Head Bolts | M6–M64

Half thread hex bolts, manufactured to DIN 931 and ISO 4014 standards, feature an unthreaded shank portion (grip length) below the head, with threading only on the lower portion. This design provides superior shear strength at the shank area, reduces fatigue failure, and ensures proper alignment of connected components. Available in M6 to M64 with various grip lengths, our partially threaded hex bolts are the preferred choice for structural and high-stress applications.

Material & Specifications

Size Range	M6 to M64 / 1/4″ to 2-1/2″
Standard	DIN 931, ISO 4014, ANSI B18.2.1, GB/T 5782
Material	Carbon Steel (4.8, 8.8, 10.9, 12.9), 304 SS (A2-70), 316 SS (A4-80), Alloy Steel
Surface / Coating	Hot-Dip Galvanized (HDG), Electroplated Zinc Blue/White, Color Zinc, Dacromet, Multi-Element Alloy Co-Permeation
Tensile Strength	400-1220 MPa (varies by grade)
Grip Length	Standard per DIN 931, custom grip lengths available upon request

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

• Unthreaded shank provides superior shear strength and fatigue resistance
• Precise grip length ensures proper clamping force and component alignment
• Hexagonal head allows high-torque tightening with standard tools
• Thread-rolled for enhanced fatigue life and surface hardness
• Ideal for shear-critical applications in structural steel connections
• Full material traceability with EN 10204 3.1 certificates

Applications

• Structural steel connections in buildings and bridges
• Heavy machinery and equipment requiring shear-resistant fastening
• Automotive suspension and chassis critical connections
• Pressure vessel and boiler assembly
• Wind turbine and power generation equipment
• Mining and heavy-duty construction equipment

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