TIG welding magnesium properly is a skill only a very few welders possess. And, understandably so since the metal itself is super tricky and full of surprises. So, how to TIG weld magnesium properly in a way that does justice to both the material and welding process?
Certain tips and tricks go into tig welding magnesium perfectly. For instance – you need to start by determining whether the base metal is actually magnesium. In addition to the metal detection and the welding procedure itself, aftercare is also important.
However, there’s no use in knowing all the facts if you fail to carry on the actual procedure. Because that is how you’ll find out whether you’re doing anything wrong or not. So, let’s take a look into the proper instructions for TIG welding magnesium and the related inquiries.
How To TIG Weld Magnesium In 6 Steps
Before we get on to the more intricate matters, let’s settle down on the procedure first. Here are the step-by-step instructions on how to TIG weld magnesium properly.
Step 1: Identifying The Base Metal
It’s often hard to figure out what metal you’re working on because they all more or less look the same. And it’s even harder to separate magnesium from aluminum as they are both structurally and visually, similar to each other.
So, that’s a big problem. The methods for tig welding magnesium and tig welding aluminum are completely different. As a result, proceeding to apply the wrong method on one of them might result in catastrophic results.
Okay, okay, maybe thinking of it as a ‘catastrophe’ is too much of a stretch. But considering how valuable both of these metals are, it’s a shame to see them go to waste. They have unique properties and that’s why they are an integral part of most aerospace designs.
In fact, all those helicopters and airplanes that you see from time to time, integral parts of the inner gears and frameworks of such structures are made from aluminum and magnesium alloy. And why? Because they have a light build but strong structural integrity.
So, it doesn’t make sense to let such precious metals go to waste for no reason, does it? Precisely. That is the primary reason why you should always check out the base metal before proceeding to weld it.
And don’t worry. You can easily figure out which metal is which by some super simple tricks. And we will elaborate on that bit fully with separate instructions in just a while. Let’s find out about the actual welding mechanism first.
Step 2: Alloyed Composite Identification
Only identifying whether the metal is aluminum or magnesium isn’t enough when it comes to TIG welding. You have to thoroughly check the metal’s alloy composition as well.
Since magnesium is a highly reactive metal in nature, it’s rarely found in free form. As a result, it always comes mixed with some other metals like aluminum, zinc, zirconium, thorium, etc. And these special combinations are what are known as magnesium alloys.
Out in nature, you’ll find several types of magnesium alloys like these. Again, the base piece that you’re working with could also end up being pure magnesium. It’s indeed a rare occurrence but it’s not impossible.
Thus, after identifying the welding piece as magnesium, your next job is to identify the correct alloy of the metal. This is a highly important step as identifying the right alloy will directly determine your next step.
Remember how you can’t use the same welding method for aluminum and magnesium? The same stands true for the alloys as well. Because with alloy composites, you’ll need to use filler metals in later stages.
And depending on the combined metal, the choice of filler metal will continue to change as well. Not all of these filler metals can withstand the same temperature. As a result, it’s super important to know what alloy composite to work with before preheating the mixture.
Actually, not the heating temperature, you’ll realize the appropriate voltage settings and electrode type too. Needless to say how important these two factors are for matters like welding and cutting down metals and minerals.
But how can you figure out or identify the right type of alloy composite? Well, contacting the original manufacturer should give you an appropriate idea. Since they are the ones who provided you with the composite, they should have all kinds of history about it alongside.
And that history will help you to not only figure out the alloy type but also the proper equipment. All welding material comes with guidelines that specify what to use and what not to use. So, you need to thoroughly read such instructions before starting.
However, it’s not always possible to get in touch with the manufacturer due to unavoidable reasons. It becomes much harder to identify the alloy composition properly when that happens. But that being said, it’s not impossible to do so if you have the skills.
The main hindrance in identifying a magnesium alloy that comes without proper instructions is to find accessible pieces. If you carry out the experiments on a large scale, you might end up destroying most of the welding piece itself.
That’s why it’s important to look for expendable pieces that you can work on with ease. It’s best if you have some scraps i.e. bits and pieces alongside the main boulder. But, if you don’t, you’ll most likely have to break out a small part to continue with the experiment.
Such experiments include – figuring out the strength to weight ratio, differences in molecular weight of the compounds, etc. Again, you can also carry out several reactions to see how each of the alloys reacts with a certain compound.
All in all, it’s pretty basic level knowledge for a welder to have in their arsenal. But if you need some help remembering them correctly, you can contact the American Welding Society.
They own the entire library of Welding Handbooks to help welders with every possible situation that they may face. So, feel free to take the help of these handbooks if you suddenly get stuck during the welding process.
Step 3: Confirming The Welding Area
Now that all matters of metal and alloy are finally resolved, time to carry on with the actual welding! And the first step in preparing the magnesium for welding is to confirm the specific welding area.
This helps to clean and properly prepare the piece of the welding metal. That way, you can have a clear-cut idea on which part to work on and how to systematically progress. In short, it’s like this little map that later directs you in the subsequent processing period.
You can either create a mind map for the specific area if you’re experienced enough. Or, you can take a metal marker and just draw around the edges you’ll work on later. You can also use random board markers since it’s a temporary map.
Just don’t use any permanent marker or anything like that. Those can cause unwanted chemical reactions including passive corrosion and stuff. Plus, it’s another hassle if you can’t simply wipe off the marking. So, it’s just best, in general, to refrain from using such markers.
Step 4: Grinding The Welding Area
After you have chosen which area you’ll work on, time to bring in the big guns. Now you can start grinding the area which is an important step of the welding procedure. It will help you to fill down the area or lay beads throughout the base.
However, instead of grinding, some welders prefer to boldly crack up the surface. And then they proceed to fill or cover up the crack with the filler metal or magnesium beads. But, we would highly recommend not to go down that road as it’s not as full-proof as simply grinding.
Many may disagree but grinding is actually better than cracking up the surface. Because while you’re boldly cracking, you can’t guarantee equal force on all points of the surface. As a result, some parts get smashed a little too deep while the others, not so much.
On the other hand, you have a better chance of equal pressure distribution during grinding. That way, all surface points are more or less equally hit and there are no visible irregularities.
Furthermore, it’s easier to fill the base when you start by grinding. As mentioned above, cracking results in improper openings. And since magnesium is the lightest structural metal, it can’t fill up the huge gaps properly.
Only the upper surface is kind of filled and the rest not so much as the metal is too lightweight. So, as you can understand already, it kind of creates a structural imbalance of some sort. And that’s not good for the welding piece in the long run as it becomes vulnerable.
Meanwhile, since all the gaps are more or less equal in dimension after grinding, the filling becomes easier. The filler metal can easily reach all the nooks and crannies with no extra effort that way. As a result, it can properly bind to the base and becomes structurally sound.
Step 5: Utilizing Time Properly
Welding indeed takes a lot of concentration and with that, loads of time. So, everyone looks for ways to not make the procedure so tedious and time-consuming. And that’s where they make a huge mistake. While trying to do the work more quickly, they end up compromising on the quality of the work.
Again, some may end up skipping certain steps altogether which results in a complete failure. That way, not only are the welding pieces destroyed in the process but they also have to start the whole process anew. As a result, they actually end up having to do double the work.
The moral of the story – don’t use cheats that you aren’t 100% sure will work out. Also, do not under any circumstances, compromise on the work itself. You may make a few mistakes on your first few tries, which is completely okay.
But purposely using shortcuts that reduce the welding quality is completely advised against. Because how structurally sound a framework is directly correlated to the quality of welding. Now, do you see why we recommend grinding instead of simply cracking the surface?
Precisely. Cracking may take less time and effort but it’s not a reliable method in the long run. That’s why even though grinding may take much longer and a higher level of concentration, it’s the only way to go.
However, there are indeed some tried and tested methods for lowering down the time with the grinding procedure. Professional welders over ages have intricately tried out these methods and slowly perfected the application to reduce the grinding period.
For instance – you can use a coarse carbide burr while grinding the metal. That way, you’ll cover sufficient space in one go while grinding. Using a smaller burr will increase your grind to space ratio and thus, will end up taking way longer.
Again, you can take a few minutes to thoroughly clean the metal before starting to grind. Because magnesium is actually quite porous due to its lightweight structure. So, if you don’t clean it in advance, you might find it troublesome to navigate while grinding.
You can use a chromic acid solution to thoroughly clean the metal quickly. Here are the components that you can include in the cleaning solution:
- Chromic acid (24 oz)
- Sodium Nitrate (40 oz)
- Calcium Fluoride (⅛ oz)
- Water (50/60 oz)
Basically, use enough water to make a gallon of this special cleaning solution. That much amount is enough to completely soak and clean the metal thoroughly. You can let the concoction soak the metal for about an hour to make sure it takes effect.
And if you want the reaction to happen faster, here’s a great tip. Heat up the welding metal in advance in an appropriate oven for a few minutes. The high temperature will highly accelerate the rate of the overall reaction.
As a result, when you apply the concoction to a preheated magnesium piece, it will get cleaned much faster. However, make sure to wear protective hand and eye gloves while doing this and the concoction is quite corrosive. And don’t handle the heated magnesium directly.
Step 6: Filling The Gaps
At last, you need to fill up the gap caused by grinding with the filler metal. You can use multiple filler metals for this part. But you’ll find most welders using the AG 92 A filler rod for this purpose.
The reason why this rod is used is that it’s generally an all-purpose filler. So you can’t really go wrong with it while welding. And they are quite reasonably priced as well.
Anyway, while heating the welding area, it’s important to remember that magnesium heats up easily. It starts to melt around 800-830 degrees Fahrenheit and goes all the way up to 1200-1300 degrees Fahrenheit.
So, remember to set the temperature properly before starting to weld. And use inert gases, preferably Argon as a buffer because reactive gases or metals will catch fire at this temperature. And of course, don’t forget to use alternating current for magnesium welding.
Factors To Consider Before Tig Welding Magnesium
Tig welding is already a pretty complex procedure. And magnesium’s tricky appearance makes it even more complex. Here is why it’s comparatively harder to tig weld magnesium:
Magnesium Is Quite The Flammable Substance
Even though it’s metal by nature, magnesium is one of the highly flammable metals. The lattice structure is pretty lightweight and thus, it’s super reactive compared to other solid metals.
And no, unlike sodium, it doesn’t catch fire instantly whenever it finds its way to oxygen. But, if the temperature goes over the limit, it can continue to burn at a level of 4000° F.
In fact, since it’s an alkaline earth metal, it instantly produces oxygen after burning in presence of water vapor. This oxygen again acts as the corresponding fuel for more burning. Like this, it becomes a consecutive cycle until all the metal is finally converted.
And it’s not that easy to put out the fire once magnesium starts burning. You have to completely remove oxygen from the equation to stop the reaction from progressive further. And needless to say, sucking all the oxygen out of the room isn’t exactly a viable occurrence.
Well, thankfully, you can just temporarily remove the oxygen from around the metal by covering it with sand. Cement dust and fire extinguishers also work just as fine. Just make sure to wear face masks since both the C02 and dust particles are pretty harmful to humans.
Magnesium Has A Lightweight Structure
How lightweight a substance will depend on the intermolecular distance between the particles in the lattice structure. And the more densely these particles are surrounded, the heavier that metal is i.e. weighs.
And with magnesium, the intermolecular distance is comparatively more compared to other metals. Thus, resulting in the lack of weight. Furthermore, the greater distance leads to a fragile lattice, which means the metal is full of microscopic pores in it.
While in circulation, slippery substances like oil, dust particles, etc. get stuck in these pores. And that’s why it’s hard to fully insert the filler material into them while welding. That results in a weak structure later on which is why you have to keep cleaning as you keep welding.
Magnesium Easily Gets Oxidized
Magnesium is one of the metals that easily gets oxidized. And in contact with oxygen, it creates magnesium oxide which develops a layer of this oxidized substance on the surface.
Just like the porous structure, this oxidized layer makes the material too troublesome to work with as well. That’s why you have to prepare several cleaning solutions like the chromic acid one before welding magnesium.
Again, using acetone works just as fine if you are working with smaller pieces. You can use this concoction to clean the filler rods easily with just a soft cloth. However, don’t handle acetone or the chromic acid mixture directly as they are pretty corrosive.
How To Determine Whether The Metal Is Magnesium Or Aluminium?
Since magnesium and aluminum have similarities in appearance, it’s often hard to differentiate them at first glance. But to carry out the welding procedure properly, you do have to figure out what you’re working with.
Thankfully, there is a super easy reaction that you can do with everyday objects like vinegar. Because after all, metals are metals and they will one way or the other react with other substances.
By observing the differences in such reactions, you can tell apart magnesium from aluminum. For argument’s sake, let’s put a few drops of vinegar on the aluminum surface. Since aluminum is an alkali metal, it will produce hydrogen as a by-product of the reaction.
And since hydrogen is a gas, it will just evaporate away leaving no physical traces. The other product, however, is a bit corrosive and will stain or blotch the surface in a few hours.
Magnesium, on the other hand, is an alkaline earth metal. Hydrogen is also produced when these types of metal react with acetic acid i.e. vinegar. But, the other by-product here is magnesium acetate, which is actually soluble in vinegar. Nice twist there, right?
Anyway, since the product itself is again soluble, the remaining vinegar starts to fizzle out. Because the temperature increases substantially due to the corresponding reaction. So, if you see it fizzle out, rest assured that you’re indeed working with magnesium.
How To Prepare Your Equipment For Welding Magnesium?
Here’s how you can properly prepare your equipment for welding magnesium:
Selecting The Electrode
You can use whatever type of electrode suits the magnesium TIG welding procedure. However, professional welders tend to use the zirconium alloyed tungsten variant of the electrode. It gets the job done quite efficiently and pretty easy to get your hands on as well.
Fixing The Electrode
If you’re used to aluminum welding, your equipment set-up will remain fixed so that the electrons jump to the electrode. You’ll need to change this part up for magnesium welding. Fix it so that the distance of the arc gets as much closer to the electrode as possible.
That way, the set-up will get fixed in such a way that magnesium gets to jump from the electrode. And not the other way around. It may seem like a slight difference but it’s literally the very soul of the mechanism.
Selecting The Filler Metal
Like the electrode type, you’ll also find a bunch of options for the filler metal. But as mentioned above, the AG 92 A is something that you can use without any extra hassle. It’s reasonably priced, easily accessible, and does the job perfectly. What more could you want?
However, you have to really check out the metal before melting the filler rod. Because magnesium is super easily oxidized. And since the rod is quite thin, it’s even more prone to instant oxidation.
That’s why you have to dip a cotton cloth in acetone and wipe off the oxidation layer right before welding. That way, you’ll get to insert intact metal while welding. Remember, the longer you let the intact rod sit in the air, the sooner it will start to get oxidized.
Selecting The Shielding Gas
You also need to use proper shielding that will keep the surrounding areas safe while you weld. And it’s especially important while TIG welding magnesium as the metal itself is quite flammable. Without proper precautions, the sparks can fly off and cause a massive fire.
So, to prevent that, inert gases act as gaseous shielding purpose. And most welders prefer to use argon as it provides the best backup against such cases. The thick fog of argon will restrict the extra oxygen from coming inside and thus, prevent an unwanted explosion.
Switch The Current
Everyone instantly switches to direct current whenever they think of welding something. But since magnesium has different properties, direct current is not going to cut it. You’ll need to switch to an alternate current so that the filler rod can thoroughly puddle during welding.
How To Properly Preserve The Magnesium After Welding?
Aftercare is just as important as the actual welding procedure. Here are a few tips on how to properly preserve the magnesium after welding:
- Check for level distortion by using a standard lever or anything that covers the circumference. If it is, use a bold object and hammer down the bumpy places to level the surface.
- Look for any additional cracks that may have occurred during welding and grinding. If you find any, fix them.
- Try to weld the inner parts first before you get to the outside surface. It helps with keeping the base area fully leveled.
- Try to apply a corrosion-resistant concoction to the entire welding piece at the very end. That will greatly help out with the unwanted oxidation and rusting.
So, how to TIG weld magnesium properly after all? Turns out, even though the procedure is quite tricky, it’s not impossible at all. With proper dedication and a little bit of experience, you, too, can become a master at welding magnesium perfectly.