Magnesium Alloy Fasteners: The Lightest Structural Metal in the Bill of Materials
At 1.8 g/cm³, magnesium alloys are the lightest structural metals in commercial use — 35% lighter than aluminum. In weight-critical housings, magnesium fasteners close the loop.
Bottom line: for most Anti-Galvanic Corrosion applications the decision comes down to load, environment and assembly method — the Anti-Galvanic Corrosion guide walks through the selection.
Where magnesium hardware makes sense
AZ91-family cast or machined fasteners serve camera and drone structures, portable equipment frames and interior automotive parts — joints where the parent metal is magnesium and the fastener must not become a galvanic spear. Matching fastener alloy to parent alloy eliminates the worst couple.
The galvanic reality
Magnesium is the most active structural metal: coupled with steel or aluminum in an electrolyte, it corrodes preferentially — and fast. Managing this defines magnesium engineering:
- Isolate dissimilar fasteners with coated steel (zinc-nickel), nylon washers or sealed joints.
- Prefer magnesium or compatible-aluminum fasteners for through-wall joints.
- Seal faying surfaces; keep electrolytes out and the couple stays theoretical.
Strength and cost position
AZ91 delivers ~230–260 MPa — between cast aluminum grades and 6061-T6 — at the lowest density. Topprecision supports magnesium-structure programs with compatible fastener sets, galvanic-compatibility test data, and coating recommendations validated in salt-spray joint testing.
Fastener material comparison
| Material | Tensile (MPa) | Density (g/cm³) | Best for |
|---|---|---|---|
| Steel 8.8 | 800 | 7.85 | General structural, machinery |
| Steel 12.9 | 1220 | 7.85 | Weight-critical, tooling |
| Stainless 304 (A2-70) | 700 | 7.93 | Indoor, food, corrosion-resistant |
| Stainless 316 (A4-80) | 800 | 7.98 | Marine, coastal, chloride |
| Aluminum 7075-T6 | 570 | 2.81 | Weight-critical aerospace |
| Titanium Grade 5 | 900 | 4.43 | Aerospace, medical, high cost |
Need help selecting the right fastener material?
Toprecision cold-heads and CNC-turns fasteners in steel (4.6–12.9), stainless 304/316/410, aluminum 6061/7075, titanium Grade 5 and engineering plastics. Send the service environment and load requirement — we will recommend the material and grade with tensile test data. Request material selection support.
