High Strength Nut

High Strength Nut — Grade 10/12 Structural Heavy Hex Nut | ASTM A563 / DIN 6914

High strength nuts are engineered for critical structural connections where maximum load capacity and safety are paramount. Manufactured to DIN 6914/6915, ASTM A563 (DH/DH3), and GB/T 1231 standards, our high strength nuts are available in Grade 10 and Grade 12 with sizes from M12 to M48. Designed to pair with high strength structural bolts (Grade 10.9/12.9), these nuts undergo rigorous heat treatment and hardness testing to ensure reliable performance in steel structures, bridges, wind towers, and heavy infrastructure projects.

Material & Specifications

Size Range	M12 to M48 / 1/2″ to 2″
Standard	DIN 6914/6915, ASTM A563 (DH, DH3), GB/T 1231, EN 14399-4
Material	Carbon Alloy Steel (Quenched & Tempered), 42CrMo / 35CrMo
Surface / Coating	Hot-Dip Galvanized, Dacromet, Multi-Element Alloy Co-Permeation, Phosphated + Oiled
Grade	Grade 10, Grade 12, ASTM A563 DH (150 ksi min tensile)
Hardness	250-353 HV (Grade 10), 290-353 HV (Grade 12)

Surface Treatment & Zinc Coating Quality

High strength fasteners require specialized coating processes that do not compromise mechanical properties through hydrogen embrittlement. We offer the following premium treatments:

• Hot-Dip Galvanizing (HDG) — Thick zinc layer (54-120μm per ASTM A153 Class C) providing exceptional corrosion protection for outdoor structural steel. Centrifuge-spun for uniform coating thickness. Salt spray resistance: 500-1,000+ hours. Compliant with ISO 1461.
• Electroplated Zinc Blue-White (Zn Blue/White) — Bright silver-blue finish with 5-8μm zinc layer. Cr3+ trivalent passivation, RoHS compliant. Suitable for grade 10.9 applications with controlled hydrogen embrittlement risk management (baked within 4 hours post-plating).
• Color Zinc / Yellow Zinc (Iridescent Passivation) — Golden-iridescent multi-layer passivation providing 150-250 hours salt spray resistance. Preferred for structural connections requiring visual inspection identification of coating type.
• Dacromet Coating — The preferred coating for high strength fasteners. Water-based zinc-chromium flake coating applied at low temperature (<300°C) with ZERO hydrogen embrittlement risk. 1,000-1,500 hours salt spray resistance. Ideal for Grade 12.9 structural bolts in coastal, industrial, and seismic applications.
• Multi-Element Alloy Co-Permeation — Zinc-aluminum-magnesium-rare earth alloy diffusion layer providing 2,000+ hours salt spray resistance. Self-healing at cut edges and scratches. Used in critical infrastructure: cross-sea bridges, wind farms, nuclear power facilities.

Key Features

• Quench and temper heat treatment ensures consistent mechanical properties
• Heavy hex pattern provides larger wrenching surface for high-torque applications
• Guaranteed hardness matching with companion high-strength structural bolts
• Charpy V-notch impact testing available for low-temperature service (-40°C)
• Full lot traceability with 3.1 material certificates per EN 10204

Applications

• Steel structure buildings and high-rise construction
• Bridge connections and highway guardrail systems
• Wind turbine tower flange connections
• Power transmission towers and substations
• Heavy machinery, mining equipment, and offshore platforms

Why Choose BoltNutsPlus?

• ISO 9001:2015 Certified Manufacturing — consistent quality you can trust
• 15+ Years of Export Experience — serving 40+ countries worldwide
• Full Traceability — material certificates (EN 10204 3.1) and test reports included
• Custom Packaging & OEM/ODM — your brand, your specifications
• Third-Party SGS / Bureau Veritas Inspection Available
• 24-Hour Quote Response — same-day reply for urgent requirements