Materials

SAE J429 Grade 5

• Manufacturing Considerations:

  • Medium carbon steel, quenched & tempered.

  • Relatively easy to machine and thread.

  • Requires controlled heat treatment for consistent mechanical properties.

• Performance in Fasteners:

  • Minimum tensile strength ~120 ksi.

  • Provides a balance of strength and ductility.

  • Less brittle than higher-strength grades, making it reliable for general-purpose bolting.

• Common Applications:

  • Automotive, agricultural machinery, light industrial equipment.

  • Engineered fasteners where strength is needed but extreme loads or temperatures are not present.

SAE J429 Grade 8

• Manufacturing Considerations:

  • Medium carbon alloy steel, quenched & tempered to a higher strength than Grade 5.

  • More difficult to machine than Grade 5 due to higher hardness.

  • Requires careful processing to avoid hydrogen embrittlement during plating or coating.

• Performance in Fasteners:

  • Minimum tensile strength ~150 ksi.

  • High strength with less ductility than Grade 5.

  • Designed for heavier, more demanding applications where failure would be critical.

• Common Applications:

  • Heavy trucks, construction machinery, powertrain components, and engineered fasteners in high-load assemblies.

  • Used where maximum clamp load and resistance to shear are needed.