Selecting the right filler: GTAW overview

The ordinary person welding TIG may find a lot of confusion over which filler metal to use, since there are so many alloys and types of metal that can be joined with the GTAW process. For steel, many different types of rods can be used, for sure. One of the factors that cause confusion is that filler rods for Oxy fuel welding appear identical. However, these are easily weeded out by the identifying prefix of "RG" that identifies them as a gas rod. Gas rods when used accidentally for TIG can make for a very aggravating experience.

For steel there are three common filler rods that are generally used. These are the ER 70S-6, ER 70S-2, and ER 70S-3. ER 70-S2 is an exceptionally well flowing rod, used a lot with chrome moly applications. ER70S-6 is a great all around rod, with excellent wet in, because of the high level of deoxidizers. ER 70S-3, is perhaps the least desirable with very little deoxidizers. Metal has to be exceptionally clean for good results. Dull looking, gray welds will still likely result in the hands of a beginner.

Aluminum filler is generally available in many welding supply stores in two common forms. The most common perhaps is ER 4053. It works well with many common types of aluminum. It's fairly soft, and makes a great puddle. As far as the most commonly encountered aluminum, it's quite possible that 4053 will weld it. However, ER5356 is also is a very common rod with good strength. It's a good choice that gives a good appearance, particularly on anodized aluminum. It's a little more expensive, but usually the results are quite impressive, with a good flow and bead profile.

Stainless filler rod offers several choices. However, two rods are usually all you'll need. 308 or 308L is a great general purpose stainless rod that flows smoothly without much effort. It can be used to join most stainless to other stainless steels. 316L is another great rod to have around, particularly for maximum corrosion protection and use in the restaurant industry. It flows well, and makes a shiny, long lasting joint.

All of these filler rods cost money and are typically sold by the pound. Some exotic alloys may go as high as 30, even 50 dollars/lb. It's quite clear that it's not economically feasible to buy every single category of filler rods for every application. Even if you wanted to, the sheer storage space and requirements would be difficult to maintain. What is generally the best thing to do is to buy a rod or two (sometimes they have free samples) from the local welding supply and test them out in various applications. Then buy the rod, a pound or two at a time, that best fits you that works across the broadest range of materials. Whatever you buy, at some point you will have to buy something you didn't think you'd need. Regardless, though, start slow, buy buying what you'll need most commonly first, then add to your supply as you can afford it.