Material Grades – High Tensile Fasteners

High tensile fasteners are specially manufactured to withstand high levels of stress and load. They are stronger than standard fasteners and are commonly used in heavy-duty industrial, structural, automotive, and engineering applications where superior strength and performance are required.

What are High Tensile Fasteners?

High tensile fasteners are made from medium carbon steel, alloy steel, or other heat-treated materials that are capable of handling heavy loads without breaking or deforming. These fasteners are typically heat-treated (quenched and tempered) to increase their hardness, strength, and fatigue resistance.

Common Material Grades for High Tensile Fasteners

1. Grade 8.8 (Metric)

  • Material: Medium carbon steel, heat-treated
  • Tensile Strength: Minimum 800 MPa
  • Yield Strength: Minimum 640 MPa
  • Applications: Automotive, machinery, construction, general engineering
  • Color Code: Usually black or plain finish

2. Grade 10.9 (Metric)

  • Material: Alloy steel, heat-treated
  • Tensile Strength: Minimum 1040 MPa
  • Yield Strength: Minimum 940 MPa
  • Applications: High-stress applications such as heavy vehicles, engine parts, and structural assemblies
  • Color Code: Usually black or zinc plated

3. Grade 12.9 (Metric)

  • Material: Alloy steel, quenched and tempered
  • Tensile Strength: Minimum 1220 MPa
  • Yield Strength: Minimum 1100 MPa
  • Applications: High-load mechanical and industrial uses, critical bolting applications
  • Color Code: Usually black oxide finish

4. SAE Grade 5 (Imperial)

  • Material: Medium carbon steel, quenched and tempered
  • Tensile Strength: Approx. 830 MPa
  • Applications: Automotive and machinery components

5. SAE Grade 8 (Imperial)

  • Material: Medium carbon alloy steel, quenched and tempered
  • Tensile Strength: Approx. 1500 MPa
  • Applications: High-stress and heavy-duty applications, such as suspension systems and engine mounts

Key Features of High Tensile Fasteners

  • High Strength: Designed to handle large mechanical loads and vibrations
  • Fatigue Resistance: Suitable for dynamic applications with repetitive stress
  • Durability: Long-lasting performance under extreme conditions
  • Versatility: Available in bolts, screws, nuts, studs, and more

Applications of High Tensile Fasteners

  • Construction and structural steelwork
  • Automotive and heavy vehicle manufacturing
  • Earthmoving and mining equipment
  • Industrial machinery
  • Bridges, railways, and tunnels
  • Aerospace and defense components

Standards and Certifications

High tensile fasteners are manufactured to meet international standards such as:

  • ISO 898-1
  • DIN EN ISO
  • ASTM A325 / A490
  • BS 3692
  • SAE J429