## Common ground
All options are bolts made from different metallic materials, used for fastening or structural applications.
## Options at a glance
**7318.15 – Iron/steel**
- **Defining trait:** Most common material; offers high strength and durability.
- **Typical examples:** Car engine bolts, construction fasteners.
- **Best fit when:** High tensile strength and cost-effectiveness are needed.
**7415.33 – Copper**
- **Defining trait:** Excellent electrical conductivity and corrosion resistance.
- **Typical examples:** Electrical connectors, marine hardware.
- **Best fit when:** Conductivity or resistance to saltwater corrosion is essential.
**7508.90 – Nickel**
- **Defining trait:** High heat and corrosion resistance; used in extreme environments.
- **Typical examples:** Aerospace fasteners, chemical processing equipment.
- **Best fit when:** Exposure to high temperatures or corrosive chemicals.
**7616.10 – Aluminium**
- **Defining trait:** Lightweight with good corrosion resistance.
- **Typical examples:** Aircraft components, consumer electronics.
- **Best fit when:** Weight reduction is critical and strength demands are moderate.
**7907.00 – Zinc**
- **Defining trait:** Often used as a coating (galvanizing), not typically for structural bolts.
- **Typical examples:** Galvanized fasteners, decorative hardware.
- **Best fit when:** Corrosion protection via coating is the primary purpose.
**8101.99 – Tungsten**
- **Defining trait:** Extremely high melting point and hardness; rare for standard bolts.
- **Typical examples:** High-temperature industrial tools, specialized equipment.
- **Best fit when:** Extreme heat resistance required (e.g., furnace parts).
**8102.99 – Molybdenum**
- **Defining trait:** High strength at elevated temperatures; used in specialized alloys.
- **Typical examples:** Turbine blades, high-performance engines.
- **Best fit when:** Operating under extreme thermal stress.
**8104.90 – Magnesium**
- **Defining trait:** Very lightweight but prone to corrosion and flammability.
- **Typical examples:** Racing car parts, aerospace components.
- **Best fit when:** Weight savings outweigh material limitations.
**8108.90 – Titanium**
- **Defining trait:** High strength-to-weight ratio and excellent corrosion resistance.
- **Typical examples:** Aircraft, medical implants, high-end sports equipment.
- **Best fit when:** Need for lightweight, strong, and corrosion-resistant fasteners.
## Key differences
| Material | Strength | Weight | Corrosion Resistance | Heat Resistance | Common Use Case |
|---------------|----------|--------|------------------------|------------------|----------------------------|
| Iron/Steel | High | Medium | Moderate | Low | General construction |
| Copper | Medium | Medium | High | Low | Electrical, marine |
| Nickel | High | Medium | Very High | Very High | Aerospace, chemical plants |
| Aluminium | Medium | Low | High | Moderate | Aviation, electronics |
| Zinc | Low | Medium | High (as coating) | Low | Coated fasteners |
| Tungsten | Very High| Medium | Moderate | Extremely High | High-temp industrial |
| Molybdenum | High | Medium | Good | Extremely High | Turbines, engines |
| Magnesium | Low | Very Low| Low | Low | Racing, lightweight apps |
| Titanium | High | Low | Very High | High | Aerospace, medical |
## How to choose
- Is the bolt used in high-temperature or corrosive environments? → 7508.90, 8102.99, 8108.90
- Is weight a critical factor? → 7616.10, 8104.90, 8108.90
- Does it need to conduct electricity? → 7415.33
- Is it primarily for general-purpose fastening? → 7318.15
## Overlaps & pitfalls
- Zinc (7907.00) is often a coating, not the base material—confusion may arise if bolt is galvanized but made of steel.
- Titanium and nickel bolts can both be used in aerospace; priority should be based on strength-to-weight ratio vs. heat resistance.
- No single option dominates—choose based on **main function** (e.g., strength, weight, environment)