4.8 grade bolts

When it comes to high-strength fastening solutions, few options match the reliability and durability of 4.8 grade bolts. These bolts are engineered for general-purpose applications where moderate strength and excellent corrosion resistance are required. A key advantage is their versatility; they can be used in construction, machinery assembly, automotive repairs, and various DIY projects. For enhanced protection against rust and environmental factors, many users opt for our Zinc Plated Hexagon Bolt. The zinc plating provides a protective layer that significantly extends the bolt’s lifespan, making it ideal for outdoor or humid conditions. Similarly, our standard Hexagon Bolt offers a cost-effective solution for indoor applications where additional coating is not necessary. Both types are designed with a hexagonal head for easy installation using common wrenches or sockets, ensuring a secure and tight fit every time.


The 4.8 grade bolt is characterized by its mechanical properties and precise dimensions, which adhere to international standards such as ISO 898-1 and ASTM A307. Below is a detailed breakdown of the key parameters and specifications for the 4.8 grade bolt product line. This information helps engineers, procurement specialists, and DIY enthusiasts select the right fastener for their specific needs.

Key Mechanical Properties

  • Tensile Strength: 400 MPa minimum
  • Yield Strength: 320 MPa minimum
  • Elongation: 22% minimum
  • Hardness: 70-95 HRB (Rockwell B Scale)
  • Proof Load: 225 MPa

Material and Coating Specifications

Property Specification
Material Low Carbon Steel (Grade 4.8)
Coating Options Zinc Plated, Plain (Uncoated), Hot-Dip Galvanized
Coating Thickness (Zinc) 5-8 µm
Corrosion Resistance Salt Spray Test: 72-120 hours (Zinc Plated)
Finish Bright, Electroplated Finish

Standard Dimensions (Hexagon Head Bolts)

Diameter (mm) Pitch (mm) Head Width Across Flats (mm) Head Height (mm) Common Lengths (mm)
M6 1.0 10 4 10, 12, 16, 20, 25, 30
M8 1.25 13 5.3 16, 20, 25, 30, 35, 40
M10 1.5 17 6.4 20, 25, 30, 35, 40, 45, 50
M12 1.75 19 7.5 25, 30, 35, 40, 45, 50, 60
M16 2.0 24 10 30, 35, 40, 45, 50, 60, 70, 80

Applications and Usage Guidelines

  • General Construction: Suitable for light to medium structural connections, framing, and scaffolding.
  • Machinery and Equipment: Ideal for assembling machinery parts, motor mounts, and conveyor systems.
  • Automotive: Used in non-critical automotive components, brackets, and accessories.
  • DIY and Home Improvement: Perfect for furniture assembly, fence building, and general repairs.
  • Installation Torque: Recommended torque values range from 10 Nm for M6 bolts to 150 Nm for M16 bolts, depending on lubrication and thread condition.

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