Aug 2025
Carriage Bolts: Technical Information
| Low Carbon & Hot Dipped Galvanized Carriage Bolts – Pankaj International |
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Low Carbon Steel
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Hot Dipped Galvanized Steel
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| Description |
Round head bolt with a square neck, manufactured from low carbon steel. Designed for general-purpose fastening. |
Round head bolt with a square neck, made from low carbon steel and finished with hot dip galvanizing for superior corrosion resistance. |
| Typical Applications |
The square neck prevents bolt rotation during tightening, ideal for wood structures and non-metallic materials. |
Recommended for outdoor, marine, or moist environments due to its durable zinc coating. |
| Material |
AISI 1006–1050 or equivalent carbon steel |
AISI 1006–1050 or equivalent carbon steel with galvanized coating |
| Core Hardness |
Rockwell B70–B100 |
Rockwell B70–B100 |
| Proof Load |
33,000 psi |
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| Yield Strength |
Minimum 36,000 psi |
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| Tensile Strength |
Minimum 60,000 psi |
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| Elongation |
18% minimum |
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| Reduction of Area |
35% minimum |
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| Minimum Thread Length |
For bolts up to 6", thread length = 2 × bolt diameter + 0.025". For bolts over 6", thread length = 2 × bolt diameter + 0.50". |
Grade 5 & Grade 8 Carriage Bolts – Pankaj International |
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Grade 5
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Grade 8
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| Description |
Medium carbon steel carriage bolts, heat-treated for strength and reliability. |
Alloy steel carriage bolts, heat-treated for high strength and durability in critical applications. |
| Applications |
Used in structural assemblies, automotive frames, and general engineering where moderate strength is required. |
Ideal for heavy-duty construction, earth-moving equipment, and high-load structural joints. |
| Material |
AISI 1030–1050 grade steel or equivalent (medium carbon) |
Medium carbon alloy steel (typically 4140 or equivalent) |
| Heat Treatment |
Oil or water quenched and tempered at a minimum of 800°F to enhance mechanical properties. |
Oil quenched and tempered above 800°F to ensure superior strength and hardness. |
| Core Hardness |
Rockwell C25–C34 (For diameters 1/4" to 1") |
Rockwell C33–C39 (For diameters 1/4" to 1") |
| Surface Hardness |
Max Rockwell 30N54 |
Max Rockwell 30N58.6 |
| Proof Load |
85,000 psi (For diameters 1/4" to 1") |
120,000 psi (For diameters 1/4" to 1") |
| Yield Strength |
Minimum 92,000 psi |
Minimum 130,000 psi |
| Tensile Strength |
120,000 psi (Minimum) |
150,000 psi (Minimum) |
| Elongation |
Minimum 14% |
Minimum 12% |
| Reduction of Area |
Minimum 35% |
Minimum 35% |
| Minimum Thread Length |
Thread length is at least 2x the nominal diameter + 0.025" for bolts under 6", and 2x diameter + 0.50" for bolts over 6".
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| Finish / Coating |
Available with Zinc, Black Oxide, or Plain finish upon request. |
Usually supplied with Yellow Zinc plating for corrosion resistance. |