Classifying popular stick electrodes helps welders with decision making

The electrode numbering system helps welders make decisions on when, why, and how to use three commonly used stick electrodes: E6010, E6011, and E7018.

When you pick up a shielded metal arc welding (SMAW) holder, you face a wide choice of electrodes. But not all SMAW consumables, also known as stick, work for every material or job.

Deciding which to use and avoiding any weld defects or failures as a result of your decision comes down to multiple factors. When choosing a welding rod for a job, you should ensure it matches the base metal's composition, thickness, and tensile strength. You also need to consider joint fit-up, weld length, travel direction, and weld position.

The American Welding Society (AWS) simplified the process with a numbering system that can tell you about specific electrodes, what applications work best for them, and how they should be used to maximize performance. Let's take a look at how this works and what it means for three commonly used welding rods: E6010, E6011, and E7018.

The AWS numbering system has all stick welding electrode classifications start with the letter "E." That letter designates that it's an arc welding electrode.

The first two numbers following the "E" indicate the electrode's tensile strength. The next-to-last digit indicates position. The number "1" means it's an all-position electrode; a "2" indicates you should use the electrode for flat and horizontal positions; and a "4" means it would work best for flat, horizontal, vertical down, and overhead. The last digit covers the type of electrode flux coating, whether it's direct current (DC) or alternating current (AC), and the penetration level required to get a quality weld.

That "E" and the following four or five digits tell quite a bit about the electrode. As a welder, you’ll find yourself using certain electrodes repeatedly, most notably the popular E6010, E6011, and E7018 stick electrodes.

E6010 versus E6011 Electrodes. The first two electrodes are similar in that they both are all-purpose consumables ideal for piping, fabrication, construction, repairs, and maintenance. They are E60XX electrodes, which means they have a tensile strength of 60,000 PSI under standard welding conditions.

Both also are cellulose-coated stick welding consumables; about 30% of these cellulosic electrodes’ coating weight comes from this organic compound. The gas shield created when you burn these electrodes contains carbon monoxide, carbon dioxide, and hydrogen. The hydrogen gives both E6010 and E6011 electrodes a stiff arc, a high deposition rate, and deeper penetration into the base metal, cutting through dirty, rusty, painted, and greasy or oily surfaces.

Novice welders tend to shy away from the fast-freezing E6010 and E6011 electrodes. The slag resulting from the electrodes’ use solidifies rapidly and restrains the molten metal when you move away from the molten metal puddle, which enables you to weld overhead with minimal metal flowing out of the weld. This makes these consumables challenging for less-experienced welders to produce quality results, as one needs to get it right when the bead is laid in the joint.

Conversely, it gives experts the advantage by preventing the weld pool from shifting significantly before it solidifies, which is particularly advantageous in all-position welding scenarios. Both electrodes also produce flat weld beads that have a light slag formation that's easily removed and cleaned.

Choosing the right stick electrode goes beyond cost and preference. You also must account for the base metal you’re welding, the condition of that metal, the type of welding, and the available power source.

As similar as these two stick electrodes are, they do have differences. Along with the cellulose, the E6010 has sodium in its coating, while the E0611 has potassium. The E6010 is suitable only for DC power sources and has a tighter arc and deeper penetration than the E6011 electrode, which is rated for both DC and AC machines. That brings budget into consideration because DC-only welding requires a more powerful (and more expensive) power source.

Many welders report that the E6010 tends to run smoother than the E6011, particularly on exceptionally dirty or rusty surfaces. It can effortlessly strike through rust, grease, or other grime while the 6011 might require some light cleaning before striking an arc.

Pipe welders love using E6010 electrodes for putting a root bead on the inside of a piece of pipe, for root and hot passes, and filling and capping up to X52-grade pipe. E6010 electrodes work well for welding large-diameter pipelines in the vertical-down position ("stove-piping"). These electrodes also are capable of X-ray-quality welds out of position.

Something to keep in mind, however, is if the pipe strength is higher, you’ll also need higher-strength cellulosic electrodes that have the same welding characteristics as an E6010, such as E7010 or E8010.

E6011 electrodes produce a forceful, spray-type arc with excellent mechanical properties when used with either AC or direct current electrode positive (DCEP) power sources. They tend to be a first-choice stick consumable for repair and maintenance work when DC equipment is unavailable, and they work well with sheet metal welding and low-silicon-deposit applications.

E6011 electrodes can be used with medium- and high-carbon and low-alloy steel in such applications as general fabrication, shipbuilding and repair, rail cars, pressure vessel fittings, and galvanized steel.

Because it can cut through dirt, grease, and rust almost as well as the E6010 and run on more affordable AC machines, E6011 electrodes are popular with traveling welders, farmers, and others who need cost-effective solutions for maintenance and repair welding jobs.

E7018 Electrodes. Arguably the most popular stick electrode today is the low-hydrogen E7018, which produces quality welds with excellent toughness and high ductility. It's used for welding metals with an increased risk of weld bead cracking under certain conditions, like vibratory stress. This electrode reduces the risk of hydrogen embrittlement cracking that can occur when you’re welding thick sections of the base material.

The "70" in its nomenclature means the electrode has a tensile strength of 70,000 PSI, while the "1" in the third-digit slot again means this welding consumable has a smooth arc and a clear puddle in nearly all positions. The only direction the E7018 doesn't work in is vertical down.

The E7018 can run on any DC or AC power source, although it runs best on a DC source. Low-power equipment might not be able to run the larger diameters (3/16 in. or higher).

While there is a wide selection of E7018 electrode options on the market, all are not created equal. Typically, E7018 is followed by an "H" number (H8, H4, H4R). The number following the "H" describes the amount of hydrogen present in the weld when the electrode is stored and welded in standard conditions.

For example, an H4 means less than 4 mL of hydrogen per 100 g of weld metal. When it comes to the H number: the lower it is, the better.

An "R" following the H number (i.e., H4R) means that the electrode meets the AWS moisture absorption requirements. The electrode can be used for nine hours after the hermetically sealed package is open before it must be redried in conditions specified by the manufacturer.

While E7018 is ideal for a lot of weld types, most applications require specifically E7018 H4R electrodes: structural steel, power generation, petrochemical, pressure vessels, piping, and mild steel. It can produce more uniform weld metal, which has better impact properties at temperatures below zero.

Finally, if you have specific requirements for low-temperature applications, make sure you use an E7018-1 H4R electrode. The "-1" at the end indicates better mechanical performance at low temperatures (-40 degrees F in the case of an E7018-1).

Choosing the right stick electrode has many factors for you to consider besides cost and preference. You also must account for the type of base metal you’re welding, the condition of that metal, the type of welding you’re doing, and the available power source.

Understanding how each of these three stick electrodes work and where they excel will ultimately help you choose. And remember, not all stick electrodes are manufactured to strict standards, so you’ll also want to keep quality in mind. It's possible to get a name-brand, high-performance consumable at a price that won't break your budget.