DIN6914 HEAVY HEX Bolts

 

DIN 6914 is metric high-tensile large hexagon head bolt for HV prestressed steel structure connections, superseded by EN 14399-4 now, still widely adopted in European construction market. Matched assembly: DIN 6914 Bolt + DIN 6915 Nut + DIN 6916 Washer..

 

Strength Class: 10.9 (standard requirement)

Precision Grade: Grade C

Thread: Metric coarse thread, tolerance 6g, partially threaded shank

Available Sizes: M12 ~ M48

Material: Alloy / Carbon steel, quenched & tempered

Surface Finish: Black oxide, Hot-dip galvanized(HDG), Zinc plated

 

 

 

 

 

 

Mechanical Property	Class 8.8	Class 10.9
Tensile Strength Rm (min)	800 MPa	1000 MPa
Yield Strength Re (min)	640 MPa	900 MPa
Proof Stress Sp (min)	580 MPa	830 MPa
Hardness (min)	250 HV / 23 HRC	320 HV / 32 HRC
Hardness (max)	320 HV / 32 HRC	390 HV / 39 HRC
Elongation A (min)	12%	9%
Reduction of Area Z (min)	52%	48%
Impact Energy KV (min)	27 J (room temp)	27 J (room temp)
Typical Material	Medium carbon steel (C35 / 45#)	Alloy steel (40Cr / 35CrMo / 42CrMo)
Heat Treatment	Quenched & tempered	Quenched & tempered
Preload Capacity	Standard	~25% higher than 8.8
Typical Application	General machinery, automotive, M&E	Steel structure, bridge, heavy load, HV bolts

 

Matching Assembly Requirement Must be used as a complete set: DIN 6914 bolt + DIN 6915 nut + DIN 6916 washer. Do not mix with standard DIN934 nuts or ordinary washers.

Strength Class Restriction DIN 6914 is designed only for Class 10.9. Do not replace with 8.8 grade bolts for friction-type structural connections. Match with 10HV nuts.

Installation Rule Two DIN 6916 washers required: one under bolt head, one under nut. Washer chamfer side faces the contact surface.

Tightening Control Use calibrated torque wrench; strictly follow specified preload torque. Avoid over-tightening (thread stripping / bolt breakage) or under-tightening (slip failure). Two-stage tightening (pre-tightening + final tightening) recommended for steel structures.

Thread Condition Keep threads clean, dry, free of sand, rust, oil or grease. Do not apply lubricant unless approved by design; lubrication changes torque coefficient.

Thread Exposure After tightening, 2~3 full threads shall protrude beyond the nut. Zero exposure or excessive protruding threads are not allowed.

Storage & Handling Protect surfaces from rust, impact and thread damage before installation. Damaged bolts / nuts cannot be reused.

Once tightened to specified preload, HV bolts must not be reused.

Standard Reminder DIN 6914 is withdrawn old German standard; the current European equivalent is EN 14399-4. Confirm specification acceptance with EU clients in advance.

Application Scope Suitable for friction-grip steel structural joints. Not recommended for rotating hinge connections.

 

 

 

• Conduct regular visual inspections of bolt connections; check for corrosion, loosening, or damage to the bolt head/fracture surface.
• For critical structural nodes, perform periodic preload testing with professional equipment; replace bolts immediately if preload loss or material fatigue is detected.
• Do not perform any secondary processing (grinding, welding, drilling) on the bolts after installation, as this will damage their mechanical properties.

 

 

Packaging Options

Small packaging: Sealed plastic bags (with anti-rust oil) + cardboard small boxes (marked with specification/grade/quantity).

• Bulk packaging: Corrugated cartons + wooden pallets, iron drums (for high-corrosion protection requirements).
• Customized packaging: Labeled packaging with project numbers, anti-rust vacuum packaging, and fixed-quantity packaging for on-site construction efficiency.All packaging is designed to prevent bolt thread/spline damage and corrosion during transportation and storage.

Order Flexibility

• Support bulk and project-based customized ordering; flexible MOQ (minimum order quantity) for small-batch project needs.
• Negotiable transportation terms (FOB, CIF, EXW, DDP) and delivery schedules to align with customer construction project timelines.
• Provide door-to-door delivery service for large-scale engineering projects to ensure on-site material supply.

Certification and Quality Assurance

• Our DIN6914 HEAVY HEX bolts are certified to international quality management system standards: ISO9001:2015 and IATF16949:2016, and fully comply with EN14399 standard requirements.
• All products undergo 100% factory testing: tensile strength, yield strength, hardness, fracture groove torque accuracy, and thread precision testing; provide a complete quality inspection report for each batch.
• We offer long-term product quality guarantees and comprehensive after-sales technical services, including pre-sales installation scheme design, in-sales on-site technical guidance, and after-sales quality tracking throughout the project lifecycle.
• Provide customized non-standard tension control bolt solutions for special steel structure engineering requirements (e.g., extended shank, special surface treatment).

 

 

 

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