Dynamic Fabrication is a custom metal fabrication company based in Orange County, California. We have extensive background in magnesium welding. We are a custom fabrication facility specializing in prototype and short production runs with quick turn around. Here is a link to a video on magnesium welding a casting.
Magnesium Welding Overview
Magnesium is used in aircraft. It is used by the materials moving industry for parts of machinery and for hand power tools due to its strength to weight ratio. Magnesium can be welded by arc, resistance, oxyfuel gas, and it can be brazed. Magnesium alloys (formed with Aluminum, Manganese, Rare Earths, Thorium, Zinc or Zirconium) have a high strength to weight ratio. Magnesium is the material of choice where weight reduction is important. Magnesium is roughly 20 percent the weight of steel. It is 67 percent the weight of aluminum. Magnesium castings are strong and light. Magnesium exhibits remarkable damping capacity.
Magnesium welding employs both arc and resistance processes. It can be brazed with oxy-fuel processes. Magnesium is produced with different tempers based on heat treatment and work hardening. The strength of a magnesium weld is lower in base metal. This is minimized with gas metal arc welding because of higher welding speeds. This is not a factor in the base metals that are welded in the soft condition.
Gas Tungsten Arc Welding of Magnesium
Inert gas tungsten arc welding (TIG) is where an arc is generated between a non-consumable tungsten electrode and the welded metal. The electrode and welded metal are shielded with an inert gas, typically argon. Magnesium welding can be done with or without filler. When filler is used it has a form of wire provided to the weld. For magnesium welding filler rods may be of the same material as welded part or a lower melting range. The latter allows the weld to remain liquid until other parts of the weld are solid thus reducing the probability of cracking. During an inert gas metal arc welding (MIG) process, the arc is formed between the consumable electrode and the part to be welded. The electrode is continuously provided from the spool. The gas shield protects the welded zone and arc zone.
All precautions for welding aluminum should be observed with magnesium welding. A short arc should be used and the torch should have a slight leading travel angle. The cold wire filler metal should be brought in as near to horizontal as possible. The filler wire is added to the leading edge of the weld puddle.
High frequency current should be used for starting the direct current. Runoff tabs are recommended except the thinner materials. Uniform travel speed and weld beads are recommended. Gas metal arc welding process is used for the medium to thicker sections because it is considerably faster than gas tungsten arc welding. High speed wire feed rates may be required since the magnesium electrode wire has an extremely high melt-off rate. The normal wire feeder and power supply used for aluminum welding is usually suitable for welding magnesium.
Magnesium welding can be dangerous because the material is highly oxidizable. When magnesium is welded or machined it can burn. If ignited magnesium will burn with dangerous intensity.