Welding magnesium is very similar to welding aluminum, but it’s more “temperamental” because it reacts more intensely to heat and oxygen. It is common in high-performance car parts, chainsaws, and aerospace components.

1. The Primary Method: TIG (GTAW)

TIG is the standard for magnesium because it offers the precision needed for such a reactive metal.

• AC Current: Just like aluminum, you need Alternating Current (AC) to “scrub” the oxide layer off the surface while welding.
• Shielding Gas: 100% Pure Argon is standard, but pros often add Helium to the mix for thicker parts because magnesium pulls heat away from the weld area very fast.
• Filler Rod: You must match the alloy (commonly AZ61A or AZ92A). Using aluminum filler rod on magnesium will cause the weld to fail immediately.

2. The Safety Factor (Critical)

This is the biggest difference between magnesium and other metals:

• Fire Hazard: Magnesium shavings, dust, or fine wire are highly flammable. A magnesium fire is extremely bright and hot.
• No Water: Never use water on a magnesium fire; it causes a hydrogen explosion. You must have a Class D fire extinguisher (dry powder) nearby.
• Cleanliness: You must use a dedicated stainless steel brush. If that brush has touched any other metal, it will contaminate the weld.

3. Technical Challenges

• Identification: Magnesium looks exactly like aluminum. A quick test is to put a drop of white vinegar on a hidden spot; if it fizzes/bubbles immediately, it’s magnesium.
• Cracking: Magnesium is prone to “stress corrosion cracking.” Often, parts need to be preheated (to about 300°F / 150°C) and cooled down very slowly to prevent the weld from snapping.
• Oxidation: It oxidizes even faster than aluminum. If you don’t clean it right before you strike the arc, the weld will look like “black soot.”

Comparison: Magnesium vs. Aluminum