Whether you're a do-it-yourself welder who uses shielded metal arc welding (SMAW) only a few times a year or a professional welder who welds every day, one thing is certain: SMAW requires a lot of skill and electrode knowledge. Because variables such as storage techniques, electrode diameter, and flux composition all contribute to SMAW electrode selection and performance, arming yourself with basic knowledge can help you minimize confusion and ensure SMAW success.
- What are the most common SMAW electrodes?
- How do I decipher these AWS electrode classifications?
- The letter E indicates an electrode.
- The first two digits represent the resulting weld's minimum tensile strength, measured in pounds per square inch (PSI). For example, the number 70 in a E7018 electrode indicates that the electrode will produce a weld bead with a minimum tensile strength of 70,000 PSI.
- The third digit represents the welding positions for which the electrode can be used. For example, 1 means the electrode can be used in all positions and 2 means it can be used on flat and horizontal.
- The fourth digit represents the coating type and the type of welding current (AC, DC, or both) that can be used with the electrode.
- How do 6010, 6011, 6012, and 6013 electrodes differ, and when should each be used?
The 6010 electrodes can be used only with DC power sources. They deliver deep penetration and have the ability to dig through rust, oil, paint, and dirt. Many experienced pipe welders use these all-position electrodes for root welding passes that are located within a pipe. However, 6010 electrodes have an extremely tight arc, which can make them difficult for amateur welders to use.
The 6011 electrodes also can be used for all-position welding, except they require an AC welding power source. Like 6010 electrodes, 6011 electrodes produce a deep, penetrating arc that cuts through corroded or unclean metals. Many welders choose 6011 electrodes for maintenance and repair work when a DC power source is unavailable.
The 6012 electrodes work well in applications that require gap bridging between two joints. Many professional welders also choose 6012 electrodes for high-speed, high-current fillet welds in the horizontal position. These electrodes tend to produce a shallower penetration profile and dense slag that requires additional post welding cleaning.
The 6013 electrodes produce a soft arc with minimal spatter, offer moderate penetration, and have a easily removable slag. They should be used only to weld clean, new sheet metal.
6010 and 6011 Electrodes
The "60" in 6010 means 60,000 pounds' tensile strength (the ability to resist being pulled apart) per square inch. The "1" means it can be run in any position—flat, horizontal, vertical, or overhead.
The last number, 0 or 1, is some kind of technical jargon that I have never used in my 25 years as a journeyman or instructor. But for you engineer types, you know it has to do with flux composition, slag type, and power supply.
Both 6010 and 6011 are good electrodes. In my opinion, they are the only rods to tack with. They strike very easily and leave little slag to chip off. They also are very good when you need full penetration. They are a prime choice for welding decking, an application in which you must penetrate through the gauge metal into the joist or beam.
Crank up the machine to warp 10, and you have a portable torch. It doesn't cut that pretty, but it gets the job done in a pinch when you don't have access to an oxyacetylene rig and need to cut something in a hurry. Make sure the area around you is clear, especially below if you are working up high. Cutting with these electrodes produces big-time sparks and large globs of molten metal.
6011 runs on AC and direct current electrode positive (DCEP), while 6010 runs only on DCEP. This gives 6011 an advantage if you have an AC-only machine. I have found, and think most welders will agree, that 6010 runs more smoothly. The slag chips off better than 6011, and this is one reason it is used more often than 6011 in root passes on pipes.
Another advantage of these electrodes is the speed at which they burn. This makes them ideal for welding joists and bridging, especially the stiffening angle going from joist to joist for bracing. These two electrodes have enough strength to do the job and are much faster than 7018. They run great downhill passes where not a lot of penetration or structural strength is required.
- How do 7014, 7018, and 7024 electrodes differ, and when should each be used?
The 7018 electrodes are easy to use and contain a thick flux with high powder content. They produce a smooth, quiet arc with minimal spatter and medium arc penetration. Many welders use 7018 electrodes to weld thick metals such as structural steel. They also produce strong welds with high impact properties (even in cold weather) and can be used on carbon steel, high-carbon, low-alloy, high-strength steel base metals.
The 7024 electrodes contain a high amount of iron powder content that helps increase deposition rates and are often used for high-speed horizontal or flat fillet welds. These electrodes perform well on steel plate that is at least 1/4 inch thick. They also can be used on metals thicker than 1/2 in.
The 7018 is the backbone of structural welding. This rod runs completely different from the 6010 and 6011 rods—it is much smoother and easier. More of a "drag" rod, the 7018 is also referred to as a low-hydrogen, or "low-high," rod in the field. The flux contains almost no hydrogen, and the rod produces smooth, strong welds that are very ductile.
For this reason, these rods are used extensively in structural welding. I've used them on shopping centers, factories, powerhouses, nuclear weapons assembly plants, high-rise office towers, dams, and bridges. I've also used them on about a billion "neighbor-friend" projects.
The key word for the 7018 is versatility.
A 7018 rod literally should be dragged across the metal when welding. Along with dragging, a welder can weave it back and forth or oscillate it to feather it in on both sides. In vertical welding, some welders will count repetitions on each side of the weld pool, but this is a really bad habit to get into. As my old instructor used to scream into my ear, "Relax your hand and watch the puddle!" As long as you watch the puddle and relax your hand, you should be able to see and feel it tie into the steel. Counting doesn't guarantee a good tie-in; seeing and feeling do.
Shops, field welders, and home hobbyists often do not store 7018 rods properly. Being a low-hydrogen rod, 7018 requires an environment in which no moisture is allowed to get into the flux.
This is achieved by using a rod oven. I have seen all sorts of ovens used. I once saw a refrigerator that was converted into a makeshift oven by placing a high-wattage light bulb inside. This is done all too often and is in no way acceptable—7018 rods should be kept at 250 degrees F. If they are out in the open for less than four hours, they can be rebaked at 700 to 800 degrees F for an hour.
It all depends on the code (for instance, AWS D1.1 92 Steel Structural Welding Code) and what you are welding. I've seen only a few jobs in which the rods were stored correctly, if at all.
Another common mistake is opening the wrong end of the box. Another is throwing the boxes around during storage. Both break the flux off the rods. These damaged rods usually end up being wasted. If the flux is broken only off the tip, they can be long-arced and used. But if the flux is broken in other areas, the rod is useless. It's bad enough tossing away rods only halfway burned, but it is worse to throw away rods that have never been used at all.
If you were to ask a Ford fan, Chevy fan, or Dodge fan which truck is the best, you'd be there for hours. All three are good trucks with different pros and cons.
The same can be said of the different brands of rod. When it comes down to it, almost all are good. Some seem to run more smoothly; like most welders, I do have a preference, but can make do with any of them.
The 6010 and 6011 rods intimidate many first-time welders. Because they require more manipulation, they are a bit harder to run than 7018.
Many instructors teach only the "whip method," while others believe only in "circles" for rod manipulation. I don't care if you stand on your head gargling peanut butter, as long as your weld is sound.
- What is the best way to choose a SMAW electrode?
Next, match the electrode type to your welding position and consider your available power source. Remember, certain electrodes can be used only with DC or AC, while others can be used with either.
Assess the joint design and fit-up that you need and select an electrode that will provide the best penetration characteristics (digging, medium, or light). If you're working on a joint with tight fit-up or one that is not beveled, E6010 or E6011 will provide digging arcs to ensure sufficient penetration. For thin materials or joints with wide root openings, select an electrode with a light or soft arc, such as an E6013.
To avoid weld cracking on thick, heavy material or complicated joint designs, select an electrode with maximum ductility. Also consider the service condition the component will encounter and the specifications it must meet. Will it be used in a low-temperature, high-temperature, or shock-loading environment? For these applications, a low-hydrogen E7018 electrode works well.
You should also consider the production efficiency. When working in the flat position, electrodes with a high-iron powder content, as such E7014 or E7024, offer higher deposition rates. For critical applications, always check the welding specification and procedures for the electrode type.
- What function does the flux surrounding a SMAW electrode serve?
When you strike an arc, the flux burns and produces a series of complex chemical reactions. As the flux ingredients burn in the welding arc, they release shielding gas to protect the molten weld pool from atmospheric impurities. When the weld pool cools, the flux forms slag to protect the weld metal from oxidation and prevent porosity in the weld bead.
Flux also contains ionizing elements that make the arc more stable (especially when welding with an AC power source), along with alloys that give the weld its ductility and tensile strength. Some electrodes use flux with a higher concentration of iron powder to help increase deposition rates, while others contain added deoxidizers that act as cleaning agents and have the ability to penetrate corroded or dirty work pieces or mill scale.
- When is a high-deposition SMAW electrode appropriate?
They also cannot be used for critical or code-required applications, such as pressure vessel or boiler fabrication, where weld beads are subject to high stresses.
High-deposition electrodes, however, are an excellent choice for noncritical applications such as welding a simple liquid storage tank or two pieces of nonstructural metal.
- What is the proper way to store and re-dry SMAW electrodes?
Generally, electrodes' reconditioning temperatures are higher than the storage temperature to help eliminate excess moisture. The reconditioning environment for low-hydrogen 7018 electrodes should be from 500 to 800 degrees F for one to two hours.
Some electrodes, like 6011, only need to be stored dry at room temperature, which is defined as a humidity level not exceeding 70 percent and a temperature between 40 and 120 degrees F.
For specific storage and reconditioning times and temperatures, always refer to the manufacturer's recommendations.
Assess Your Base Metal
The first step in choosing an electrode is to determine your base metal composition. Your goal is to match (or closely match) the electrode composition to the base metal type, which will help ensure a strong weld. If you’re in doubt about the composition of your base metal, ask yourself these questions:
- What does the metal look like?
- Is the metal magnetic?
- What kind of sparks does the metal give off when touched by a grinder?
- Does a chisel “bite” into the base metal or bounce off?
To prevent cracking or other weld discontinuities, match the minimum tensile strength of the electrode to the tensile strength of the base metal. You can identify a stick electrode’s tensile strength by referring to the first two digits of the AWS classification printed on the side of the electrode. For example, the number “60” on an E6011 electrode indicates that the filler metal produces a weld bead with a minimum tensile strength of 60,000 psi and, as a result, would work well with a steel of similar tensile strength.
Some electrodes can be used with only AC or DC power sources while other electrodes are compatible with both. To determine the correct current type for a particular electrode, refer to the fourth digit of the AWS classification, which represents the type of coating and type of compatible welding current.
Specification and Service Conditions
Make sure to assess the conditions that the welded part will encounter throughout its service. If it will be used in high heat or low temperature environments, subjected to repetitive shock loading, a low hydrogen electrode with higher ductility will reduce the chance of weld cracking. Also, be certain to check for welding specifications if you’re working on critical applications such as pressure vessel or boiler fabrication. In most cases, these welding specifications will require you to use specific types of electrodes.
Environmental Job Conditions
To achieve the best results, you should always remove excessive mill scale, rust, moisture, paint and grease. Clean base metals help prevent porosity and increase travel speeds. If cleaning your base metal is not possible, E6010 or E6011 electrodes deliver a deep penetrating arc that has the ability to cut through contaminants.
Consideration of the above factors will help you overcome the challenges of selecting the correct stick electrode for your particular application. However, given the wide range of available electrodes, several solutions may exist for one application. If you need additional assistance with electrode selection, your local welding supply distributor or a company representative of a reputable filler metal manufacturer can serve as an excellent resource.