In nearly all commercial-level welding jobs that require structural steel construction or pipe welding, in either the industrial or energy sector, the welding electrodes used are specified in the contract documents and designated welding codes. But what if you are working on a repair job or a construction project not governed by welding codes or the engineer’s explicit instructions?
Now it falls to you, the welder, to select the proper welding electrode for the task at hand. This guide will assist with this responsibility by helping you narrow down your selection and pick the welding electrode (commonly referred to as “rods” in shops and on job sites) best suited to your application.
Let’s begin by looking at the two main types of welding rods.
Types Of Welding Rods
A consumable electrode is effective when the electrode and the filler metal are the same. When the electrode is brought into contact with the workpiece and becomes part of the molten weld puddle where the electrode, flux, i.e., protective coating, and the base metal all are joined together in the weld joint, you are using a “consumable” electrode. All the welding electrodes that are used with shielded metal arc welding (SMAW) are considered consumable.
Non-consumable electrodes, by contrast, are most generally associated with Gas Tungsten Arc Welding (TIG welding). In TIG welding the non-consumable electrode is secured in the TIG torch and is used to initiate and hold the arc, but at no point is to be consumed into the molten weld puddle. A separate bare metal filler is added to the molten weld metal puddle to complete the weld joint. The common electrodes of such type include Tungsten electrodes.
Welding Rod Numbers
Welding electrodes are classified based on the numbers printed on the end of each welding rod contained in the package. The numbers will tell the welder at a glance the tensile strength rating, the position the rod can be used to weld in, and the distinguishing characteristics of each welding rod.
The American Welding Society (AWS) put a system for classifying the welding electrodes based on strength, welding positions to be used, flux covering type, and alloying elements if the electrodes are alloyed.
WHAT DO WELDING ROD NUMBERS MEAN?
The numerical designations printed on each welding rod available on the market assist us in making an informed decision. For the purposes of this article, we will limit the electrode selection to the shielded-metal arc welding process (SMAW), more commonly known as “stick” welding. The criteria for selecting welding wires for GMAW (MIG) welding, FCAW (Flux-core) welding, and GTAW (TIG) welding share many of the same fundamental principles.
THE FIRST 2 NUMBERS
As per AWS designation, the first two, and in some cases three numbers on the welding rod refer to the tensile strength, i.e., the ability to resist being pulled apart, X 1,000. For example, in the designation 7018, the number “70” means that a well-made weld made with 7018 can withstand 70,000 pounds per square inch (psi) of tensile stress.
A weld using a rod classified as 11018 can withstand 110,000 pounds per square inch (psi) of tensile stress. The commonly used welding rod 6010 is only rated for 60,000 psi.
THE THIRD NUMBER
The third number refers to the position in which you can use the rod. A “1” means that the rod can be used in all positions. A “2” typically means the rod can be used flat and horizontally. Number “4” is restricted to the flat position only.
THE LAST NUMBER
The last number in the sequence refers to the class of rod or any particular distinguishing characteristic, especially the flux coverings. For example, on a 7018 welding rod, the “8” means that it is a low-hydrogen rod with basic flux covering.
The “0” in 6010, 7010, and 8010, are a class of “fast freeze” with cellulosic flux covering (meaning the molten weld puddle solidifies very quickly), making it well suited to out-of-position welding jobs. The “1” in the last number of 6011 is very similar in characteristics to 6010 but is used on AC power sources.
For the low alloyed welding electrodes, the designation may also include the alloy content in the last digit like in the case of E7018-A1 which means that the electrode contains 0.5% Molybdenum and so on.
So now that we have a baseline understanding of what the numbers mean and how to read the numerical designations of various welding rods on the market, let’s discuss how to pick the best one for your specific job requirements by understanding the rod characteristics and pros and cons of the more commonly used welding electrodes on the market.
Common Welding Rods
E6010 is a very popular and commonly used rod, and with good reason. It is easy to initiate the arc, deep penetrating, and given its spray-arc characteristics, allows for high travel speeds. It welds very well in all positions.
USES AND APPLICATIONS
6010 is commonly used in pipeline construction, refineries, gas plants, and utility piping along with its variants, 7010 and 8010. E6010 is also very forgiving of joint imperfections and surface impurities. Its “fast freeze” classification (meaning the molten weld puddle solidifies very quickly) allows the skilled welder to fill gaps in joints, within reasonable allowances. Of course, that might prove difficult, if not impossible with other kinds of electrodes. However, because of its “fast-freeze” characteristics, 6010 welds do not have the same ductility as you might get from a 7018 electrode, so it would not be a good choice for something under cyclical stress or anywhere ductility is a consideration.
E6010 digs very deep into the base metal, and running it too hot and fast can result in undercut and trapped slag inclusions. 6010 is in the cellulose family of welding electrodes and so there is a certain amount of moisture inherent in the rod. If it is allowed to dry out by sitting out too long in a dry, dusty climate, the rod can “fingernail,” where the flux tends to burn off to one side of the rod, causing the arc to favor one side of the joist over the other. When this happens, it is usually best to dispose of the rod and grab another. 6010 is best used on pipes, especially for root passes, railings, and sheet-metal applications. Because of its arc characteristics, it can result in more splatter, cleaning time, and higher costs.
The primary distinction between 6010 and 6011 is that 6011 runs on an AC power source. 6011 has long been referred to as “farmer rod.”
USES AND APPLICATIONS
In 1916, James Lincoln made the electric arc welder commercially available and started selling welding machines to farmers throughout the Midwest. The story goes that $100 got you the machine, a box of 6011 rods, and a day’s lesson in welding.
6013 is an old standby in some light-duty sheet metal applications due to its shallow penetration, high travel speed, and the fact that it is very forgiving of surface impurities.
USES AND APPLICATIONS
If one were to repair an old tractor fender or the like, this rod would be well suited to the task. Very forgiving of irregular weld joints and surface impurities like paint and rust, this rod can make quick and easy work out of minor repairs with visually pleasing welds with minimal clean-up. This rod also runs on AC power source machines. These electrodes are known for their easy use and smooth weld profiles but with limited penetration and susceptibility to cracking.
This is another very commonly used welding electrode and falls under the “low-hydrogen” classification of welding rods.
USES AND APPLICATIONS
Decades ago, structural engineers faced issues with sub-surface cracking in steel buildings, bridges, and other structures. After extensive investigation, hydrogen, a key component in moisture, was identified as the culprit and so the “low-hydrogen” (often referred to in the field as “lo-hi) series of rods came into being and has long been a staple in the structural steel welding world.
E7018 will not travel as fast as E6010 but given its “fill freeze” classification (molten weld puddle solidifies more slowly than fast freeze rods) the welds made by E7018 have greater ductility and should be considered for use in welds where ductility in cyclical stress situations may be a concern. Some examples of this might be structural steel buildings, bridges, and even construction and farm equipment. E7018, when properly used, can produce some very beautiful welds with very tight, symmetrical ripples and a smooth contour to the finished weld with minimal splatter. One potential drawback is that, if not stored properly in a sealed container or a rod oven, 7018 rods can absorb moisture in the atmosphere which can result in porosity in the welds.
E7018 can be turned down to fill in an open root situation or where there is a gap in the fit-up, again, within reasonable tolerances. Careful joint cleaning is essential though because E7018 is susceptible to porosity, often caused by surface contaminants like grease, paints, oils, or dirt. E7018 typically requires DC power sources, although AC versions of this rod can be found in any welding supply distributor.
Commonly known as “jet rod” in the field due to its high deposition rates, E7024 is a great choice of rod when you need to lay down a lot of metal in a hurry.
USES AND APPLICATIONS
Large structural beams, baseplates, columns, and large portions of heavy equipment can be welded very quickly and efficiently with 7024.
As we now know, the “2” in 7024 means that this particular rod is limited to flat and horizontal applications. But if you are on a heavy section of plate with a relatively uniform joint then this rod can be a great choice. It allows the operator to weld with a high travel speed and is very forgiving in travel angle and work angle. Similar to E7018, the slag will break off rather easily with minimal spatter in a properly completed weld.
One thing that the beginner and intermediate skill level welder should be acutely aware of is that although 7024 is very forgiving in work angle and travel angle it is still important to stay focused on the molten weld puddle. E7024 can leave small fusion voids in the weld that you may have to go back and fix, especially in fillet weld joint configurations. DC power source is required with a high amperage range capacity to run this rod, especially larger-sized electrodes.
This is a very versatile welding rod suitable for the welding of more common types of Stainless Steel found on the market. (L refers to low carbon. Too much carbon in a stainless weld can greatly diminish corrosion resistance, a defining characteristic of stainless steel).
USES AND APPLICATIONS
Because of its versatility, this rod is commonly used in maintenance and repair situations.
A good choice of electrode if the specific grade of stainless is not known with absolute certainty, E309L offers a very high deposition rate and good crack resistance. Another point worth mentioning here is that if you are ever in a situation of welding carbon steel to stainless steel, 309 has long been the choice of many a welder. Many welders and repair shops keep a small tube of 309 on the shelf for this very reason. E309L makes beautiful welds but can be tricky to run in out-of-position applications.
This is an aluminum welding rod that is highly versatile and can be used with most grades of aluminum you are likely to encounter in minor repair welding jobs. Welding aluminum can be tricky and even tougher out of position. Because of aluminum’s ability to conduct heat so rapidly, it might take a little more trial and error in practice than is required with many of the carbon steel electrodes mentioned but it can certainly be done. Since aluminum is a very soft and porous metal, it tends to absorb anything and everything it comes in contact with, especially things like grease and oils. Clean-up and joint prep are therefore particularly important when welding on aluminum. Muriatic acid, a rosebud torch, and a wire brush can all be especially useful tools for this purpose. Very similar to E7018, aluminum electrodes can attract moisture, so it is important to store them in a warm and dry place.
There are welding size and electrode charts available online that the beginner welder may find very useful when trying to select the proper rod size, but I would emphasize that these should only be used as guides, not hard and fast rules. There are many factors to take into consideration when selecting the right size welding electrode - material thickness, joint design, strength requirements, position to be welded in, etc. - that this topic warrants its own separate discussion. That being said, no guide will ever replace your eye as the judge of a properly made weld. Your completed weld should have reasonable uniformity, with no cracks, lack of fusion to base metal or other weld passes, and have minimal imperfections, like undercut, slag, or porosity.
This all comes with time and practice. Burn rods until you’re sick of it, then burn a few more. That is how good welders attain the necessary level of consistency to make the quality welds the customer depends on.
How To Store Welding Rods
Welding rods should be stored somewhere in a warm and dry environment where the flux or the outer protective coating will not come into contact with moisture or other contaminants that could be detrimental to the ability of the rod to produce sound welds, free from defects.
The E7018, which is particularly sensitive to moisture contamination, should be stored in a rod-drying oven for some time prior to use as per supplier recommendations. It is a good practice to examine the end of each rod prior to starting the weld. If there is any flux broken off the welding electrode there is the possibility of porosity at the start of the weld pass.
Welding Rods FAQ
IS 6010 SUPPOSED TO BE STORED IN A ROD OVEN?
6019 or any of the 10 series rods should never be stored in a rod oven. The 10 series rods are cellulose rods so there is a certain amount of moisture in the flux when they are new and fresh out of the package. A rod oven will dry the rods out so that the flux might fall off and peel away during welding and cause the arc to favor one side of the weld joint. When you encounter this dynamic, it is usually best to throw the rod away and get some new ones.
CAN YOU USE A WELDING ROD MORE THAN ONCE?
You absolutely can. There is no standard procedure prohibiting this. If there is enough left of the rod to make the next weld or even a few simple tack welds, and the electrode is still in good condition then there is no reason to waste it.
DOES E7018 HAVE TO BE STORED IN A ROD OVEN?
This depends greatly on several different factors.
If you are on a job working under a welding code, a rod oven will usually be either required or, at least, strongly recommended.
If you are in a cold and damp climate where the rod might come into contact with moisture in the atmosphere then a rod oven is strongly recommended.
If you are in a drier climate where moisture is not a chronic issue and you are not on a job requiring rod ovens, then it may be sufficient to keep the E7018 in a sealed container. Keep a close eye on your welds though.
If you are seeing porosity issues and if the flux on a rod looks cracked, then it may be time to dispose of it and get some new rods.