Hex Bolt 10.9 Size M8 with Class 10 Hex Nut

Dimensions (DIN 931 / DIN 933 Standard)
Note: The "Full Thread" specification corresponds to the DIN 933 standard, whereas DIN 931 is for half-thread bolts.

Thread Diameter (d): 8 mm (M8)

• Thread Pitch (P): 1.25 mm (Standard Metric Coarse)
  
• Width Across Flats (S): 13 mm (Requires a 13mm wrench/spanner)
  
• Head Thickness (k): 5.3 mm
  
• Nut Thickness (m): 6.5 mm (Based on DIN 934 / ISO 4032 standards for nuts)

Mechanical Properties

• These fasteners are manufactured from medium carbon alloy steel that has undergone a quenching and tempering process.
  
• Bolt Grade 10.9:
  
• Tensile Strength: Minimum 1,040 MPa (N/mm²)
  
• Yield Strength: Minimum 940 MPa (N/mm²)
  
• Hardness: 32 - 39 HRC

• Proof Load Stress: Approximately 1,040 MPa (Class 10 nuts are specifically designed to match the tensile strength of Grade 10.9 bolts to prevent thread stripping).

Suitable Applications

Grade 10.9 bolts are classified as High-Strength Fasteners, making them ideal for:

• Automotive Components: Chassis, suspension systems, and parts subjected to high impact, shock, or heavy vibrations.
  
• Heavy Machinery: Motor mounting points and machine frames that must withstand dynamic loads and high shear forces.
  
• Engineering Structures: Steel structure joints that require high structural integrity and safety.
  Precautions
  
• Corrosion Resistance Limitations: The black oxide finish only provides a very thin protective film for basic indoor rust prevention. It does not withstand high moisture or corrosive environments. For outdoor or wet applications, use Hot Dip Galvanized or Zinc Plated alternatives, or apply a protective coating of grease/oil.
  
• Tightening Torque: To ensure optimal performance and prevent the bolt from stretching or snapping, always use a torque wrench. The recommended tightening torque for an M8 Grade 10.9 bolt is approximately 35 - 40 Nm (depending on thread lubrication conditions).
  
• Grade Matching: Must be exclusively paired with Class 10 (or higher) nuts and high-strength flat or spring washers. Never use lower-grade nuts (such as Class 8 or standard mild steel) with high-strength bolts, as the internal threads of the nut will strip under high tension.