Grade 5

Grade 5 fasteners are medium-strength fasteners made from medium carbon steel that has been heat-treated to improve their mechanical properties. They are commonly used in automotive, construction, and industrial applications where a balance of strength and toughness is required.

Key Characteristics of Grade 5 Fasteners:

1. Material Composition: Made from medium carbon steel, often with added elements like manganese, which enhance the material's hardening capability.

2. Mechanical Properties:

   • Tensile Strength: Approximately 120,000 psi (827 MPa), making them suitable for medium-duty applications.
   • Yield Strength: Around 92,000 psi (634 MPa), providing a good balance of strength and ductility.
   • Hardness: Typically in the range of Rockwell C25 to C34, indicating a moderately hard fastener.

3. Heat Treatment: Grade 5 fasteners are quenched and tempered to achieve their desired mechanical properties, providing improved strength and resistance to wear and deformation under load.

4. Corrosion Resistance: While Grade 5 fasteners have limited inherent corrosion resistance due to their carbon steel composition, they are often zinc-plated or otherwise coated to provide a basic level of rust protection. They are not ideal for highly corrosive environments without additional coatings.

5. Applications:

   • Commonly used in automotive assembly, machinery, and agricultural equipment.
   • Suitable for bolting together parts of engines, frames, and other components where moderate strength is necessary.
   • Used in structural applications where strength is important but not as critical as in high-strength (e.g., Grade 8) applications.

6. Identification: Grade 5 fasteners can be identified by three radial lines on the head of the bolt, which distinguish them from Grade 2 and Grade 8 fasteners.

7. Standards Compliance: Conforms to SAE J429 and other relevant standards, ensuring consistency in material quality and mechanical properties.

8. Magnetic Properties: Magnetic due to their steel composition, which is typical for carbon and alloy steel fasteners.

Grade 5 fasteners are valued for their moderate strength, affordability, and versatility, making them a popular choice in various medium-stress applications where a reliable yet not overly robust fastener is required.