In this article, we will guide you on how you can choose the best rod for corroded metal but before we touch on the technical part, it is necessary for you to first know the effects of rust on welding. This is to know why certain welding rods are best to use when working with corroded metals and why other welding electrodes are simply not a good fit.
When choosing the best rod for very rusty metal, or any metal for that matter that is not cleaned properly, or for something that is impossible to clean, your best bet would be to use High Cellulose Potassium rods like 6010 and 6011. These rods have a more digging and violent arc due to the flux composition mentioned earlier so they would be the best option. The rods alone are not enough though, you also need to use DCEP and crank up your amperage a bit more to make sure you cut through the contaminants properly.
How rust affects welding?
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As a rule of thumb, steel surfaces should be cleaned of any contaminants such as oil, rust, and grease before you start. This is because surface contaminants will affect the quality of your weld. This is also the reason why rust or oxide must be removed from the surfaces beforehand.
In some cases, however, complete cleaning of the steel surface could be impossible. Sometimes, complete cleaning cannot even be performed. That is why the recommended consumables, or in other words welding rods suitable, are those that have deeper penetration and/or have a slower freezing puddle to minimize the rust affecting the quality of the weld.
In short, the effect of rust on the weld quality is the main reason why rusty metals require specific welding rods with deeper penetration, DCEP settings, and higher amperage than normal. Contaminated surfaces make the welding pool less liquid and stops it from fusing with the base metal. By product of inadequate penetration would be a weld that does not fill its purpose – hold metal together.
How to Choose the Best Rod for Rusty Metal?
A variety of factors affect the process of picking a rod best-suited for your job. A few of those factors may include the need for welding out of position, multiple pass welding, or even machine capabilities. As such, to make things simple, we would focus only on factors that would allow you to choose the best rod for regular low carbon steels.
Since rust is a surface contaminant that affects the welding puddle by slowing it down and lessens the penetration a lot, you must choose a welding rod that offers deeper penetration and preferably has a fluid welding puddle. I know that choosing the appropriate rod for metals is critical for weld strength, bead quality, and spatter minimization (when welding on rust there’s going to be plenty anyway) but you can’t be picky when you are trying to weld rusty metal.
To sum it up, in theory, a welding rod that offers deep penetration, a decent amount of slag, a slower freezing puddle, and higher levels of silicon and manganese (they help to reduce the porosity) are the best type of rod suited for rusty or dirty metals.
What is the Best Welding Rod for Rusty Metals?
I keep dancing around the penetration and whatnot, but you want answers right? Here it is. You can use 6010 and 6011 when you have to get through heavy rust because they are easier to handle in such conditions. 7018 can also work if you need more strength. Due to a fluid puddle E7018 is great, but only with a medium amount of rust on the surface. The thick slag coverage of 7018 and fluidity helps to carry out a lot of the contaminants to the surface of the weld pool.
The 6011 welding rod still seems to be the best welding rod suited for these types of metals. The 6011 welding rod is generally used for general repairs, fabrication, and pipe welding. In other words, the 6011 welding rod is best for dirty metals. This is because the 6011 welding rod offers a deep weld penetration and has a strong arc, as a downside, it produces very little slag and has a fast-freeze puddle.
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For another option, you could also use the 6010 welding rod. The 6010 and 6011 are almost identical electrodes, in fact, many people can not tell the difference between them. Like 6011, 6010 offers a deep weld penetration and also leaves a very little slag after you weld.
Despite knowing which electrode to use, the preparation for your welding process does not end there. So the following are some answers to common questions asked about the topic.
| 6010 | 6011 | |
| Tensile Strength | 60000 PSI | 60000 PSI |
| Position | All positions | All Positions |
| Polarity | DCEP | DCEP,DCEN, AC |
| Arc Characteristics | Violent | Violent |
| Flux composition | cellulose sodium (Fast Freeze) | cellulose potassium (Fast Freeze) |
| Slag Type | Thin, Flaky, does not peel | Thin, flaky, does not peel |
| Motion | Slight drag / Can whip (stich) | Slight drag / Can whip (stich) |
| Penetration | High | High |
I have a whole article comparing 6011 and 6010 here if you are interested.
Frequently asked questions:
Definitely. Rusty metal can be welded although, the welding process can be difficult and is not preferred by professionals. To ease the process, it is advised that you first clean your metal from any dirty contaminants such as rust, dirt, oil, and grease as much as possible.
There are different methods that you could use to clean rust off the metal you would use for welding. The most underrated of many of these methods is the use of sandpaper. Sandpaper is great for removing most of the contaminants except oil from hard to reach spots. As to the type of grit for the sandpaper, 80-100 would be perfect for cleaning rust. Of course, another way would be to use a grinding wheel, if you have one at hand.
You need to clean your base metals before welding. As a general rule, if you want a strong, clean, and quality weld, a clean base metal is necessary.
As to sheet metals, there is no absolute answer but In the case of stick welders, the thinnest is 1/8” but anything less than 3/16″ is already considered thin. Welding thin sheet metal with a stick welder is a skill on its own and needs quite a bit of practice to master.
The most common welding rods are 6010, 6011, 6013, 7018, and 7024 while the most common diameters for these rods range from 1/8” to 5/32”.
The best all-around welding rod is 6011 but beginners may find it difficult to use (6013 would be better for novices). Nonetheless, the 6011 welding rod is the best because it can be used to weld in any position with any polarity. It is also a fast-freeze rod but is still used to weld dirty steels.
Conclusion
It has to be noted that although all-around welding rods like 6010 and 6011 are great to use on rusty metals, for the best possible results, it is still best if you take your time to clean your workpieces before you start welding. Welding rods vary in properties such as strength, arc performance, and flux composition. Therefore, taking the extra time to clean the metals beforehand and welding with the appropriate rod will increase the quality of your welds as well as your experience in the welding world.
All in all, although the process of welding may sound difficult, keep in mind that constant practice makes perfect.
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