Here we offer information on joining magnesium, from fusion methods such as welding, bonding, Flash butt welding, and soldering to mechanical joining such as riveting, bolting or hemming magnesium alloys.
It is critical to note that although many welding vendors claim magnesium welding requires highly specialized skills and special aerospace technology. In actual fact the weldability of most magnesium alloys is far superior to most common aluminum alloys. It is has been a common process requiring no equipment different than that which is used for welding aluminum alloys, and in most cases was producing superior welds when compared to Aluminum welding at the time.
Above is a photograph from early 1933. It shows a gondola made of Dowmetal and that was flown into the stratosphere in 1933. Although this is arc welding without protective gas, this produced a welded structure sound enough for widespread use. Even safety-critical aircraft structural parts at the time used this technique. Protective gas arc welding of a magnesium wing tips is shown in the photo below.
GTAW (TIG welding) was invented by a man named Russell Meredith working for Northrop Aircraft in 1941. Northrop patented this welding process in US Patent No. 2274631 issued on January 4, 1941. This welding process has since been employed in many hundreds of thousands of safety critical welded magnesium structures.
Although argon is perfectly suitable for magnesium welding, both magnesium and aluminum welding can, at times, be improved by the use of small percentages of helium. It should be noted that gas density influence greatly the penetration of the weld and the form of the pool and therefore when fully considered in the part design and fabrication, it can improve fatigue performance as much as any single change in alloy.
One of the most crucial elements of helium welding is the dramatic improvements in strength in and around the HAZ. As can be seen above helium and or helium and argon mixes offer better weld pool edge conditions, Allowing less perfection in the execution of the welding and much better results in the same said welded structures.