How to Answer “Magnesium Corrodes” in Your Next Design Review
You proposed magnesium. The mass numbers are on the slide. And then, from the end of the table: “Doesn't magnesium corrode?”
This is not an attack — it's the question the room is supposed to ask. The proposals that die here die because the presenter either overclaims (“no, that's a myth”) or under-prepares (“I'll check”). Here is the answer that does neither.
First, concede the true part
“Untreated magnesium in salt spray? Yes, it corrodes — fast.” Say it plainly. Conceding the premise costs you nothing, because no one ships untreated magnesium, and it buys you the credibility for everything that follows. The room stops probing the moment it hears you're not selling.
Then the three-beat answer
Beat 1: alloy purity — Modern AZ91D holds iron, nickel and copper to tight limits. Tramp-element corrosion — the source of magnesium's reputation from decades ago — is a spec line now, certified per lot.
Beat 2: the coating stack — Chromate-free conversion coat plus e-coat, validated to the program's salt-spray hours. Specified as a system, because the layers are designed to work together.
Beat 3: galvanic design — The real-world failure mode is a steel fastener seated directly in a magnesium boss — a galvanic cell, not a material property. Isolation washers, coated inserts, drainage paths. Designed in, it costs nothing.
The question behind the question
If someone pushes further, they're really asking: has anyone qualified this before us? The answer is yes — magnesium ships today in automotive, drone and EV structures under standard salt-spray requirements — and the correct move is to offer the evidence, not more chemistry: coating validation data, the fastener design detail, and field precedent in your product category.
Walk in with the slide already made
This entire answer fits on one page — the numbers, the three beats, and the qualification checklist a review board expects. We've formatted it to paste straight into your deck.
Reach out and we can share a design-review one-pager (PDF) — the corrosion answer, the flammability answer, and the qualification checklist on a single page. https://www.exclusivemagnesium.com/contact-us
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