Hex Nut
Nuts · hexagon nut · finished hex nut
Definition: A hex nut is a six-sided, internally threaded fastener that mates with a bolt or threaded rod to clamp parts together.
Anatomy & Schematic
■ Body■ Internal thread
Governing standards: ASME B18.2.2 · ISO 4032 · DIN 934
Common Sizes
| Inch | Metric | Head width | Head height |
|---|---|---|---|
| 1/4-20 | M6 x 1.0 | — | — |
| 3/8-16 | M10 x 1.5 | — | — |
| 1/2-13 | M12 x 1.75 | — | — |
Representative sizes. Full dimensional data lives in the standards listed below.
Grades & Strength
| Grade | Material | Tensile (psi) | Marking |
|---|---|---|---|
| Grade 2 | low carbon steel | — | No marking |
| Grade 5 | medium carbon steel, Q&T | — | 3 radial lines |
| Grade 8 | medium carbon alloy steel, Q&T | — | 6 radial lines |
Materials
- Zinc-plated steel
- Stainless steel
- Brass
- Nylon (non-metallic)
Pros & Cons
Pros
- Universal and cheap
- Six flats give good wrench access in tight spots
- Available in every size and grade
Cons
- Can vibrate loose without a lock mechanism
- Requires a wrench on the nut side
Typical Uses
- Universal nut for bolted joints
- Mating with threaded rod
- General assembly and repair
Alternatives & Related
- Lock Nut — Resists vibration loosening
- Flange Nut — Built-in washer face distributes load
Where to Buy
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FAQ
How do I choose the right nut for a bolt?
Match the thread size and pitch exactly, and match or exceed the bolt grade. A Grade 5 bolt needs at least a Grade 5 nut.
What torque for a hex nut?
Torque depends on the bolt size, grade, and lubrication. See the torque table on the bolt page and always use a calibrated torque wrench for critical joints.