To account for all the possible, the American Welding Society (AWS), American Society of Mechanical Engineers (ASME), and other industry associations have developed classification systems for consumeables. Manufacturers still design and produce their own proprietary brands, of course, but just to keep everyone on the same page, all product names are cross-referenced to the applicable AWS and ASME classifications. For instance, a rod sold under the proprietary name "Pipemaster 60" will conform to the requirements of an "E-6010" classification. For more examples, check out this sales list posted by Hobart Brothers .
Due to the multitude of product choices out there, an experienced welder, weld technician or welding engineer will maintain a binder containing the latest order charts from multiple manufacturers or suppliers. The binder will likewise include product spec sheets that state compliance with particular AWS and ASME codes, as well as related construction code requirements. That way he or she can quickly identify what will work for a particular assignment or project.
Entry-level welders should learn the classification of common filler rods, wire and electrodes used by their companies or industry in general. They all should know a little bit about the classification vernacular. For example, you may be asked to fetch supplies from the storeroom, or order consumeables from a local welding supplier. For DIY welders, this tutorial will expedite the process of making everyday repairs and fabrications.
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If you're new to the profession, you might be a little confused about the difference between an electrode and a filler rod. In stick welding, the filler rod and the electrode are one and the same. Electricity supplied by a welding machine energizes the rod, which is attached to a metal clamp. The tip of the rod proceeds to melt into the molten pool generated in the joint the base metal. In oxy-fuel or TIG welding, however, the welder holds the filler rod in a separate hand. In this process, a gas torch produces a hot fire that melts the rod tip as both intersect at the joint of the object. In MIG welding, a spool of wire is fed by a gun. In this process the wire is heated by the electricity and melts at the tip into the molten pool. The wirefeed continues feeding more wire until the welder releases the trigger.
Stick welding on a pipe is one of the more difficult processes to learn.
(If you're still confused, take a moment to read about welding processes in the Skills to Learn section.)
Stick Electrode Classification
Stick electrodes are sold for the following metals:
AWS classifies stick electrodes according to several codes, depending on the metal type. One of the most common is AWS A5.1/A5.1M: Specification for Carbon Steel Electrodes for Shielded Metal Arc Welding. E-7018 and E-6010 are examples of rods used by pipe welders. Here's what the numbers indicate:
E - Electrode
70 - Tensile strength of the weld metal, measured in Pounds per Square Inch (PSI). Note: some countries substitute a metric unit for PSI.
1 - This single digit number tells you the most difficult welding position you can use the electrode in (1 = any position 2 = horizontal and flat; 3 = flat only; 4 = overhead, horizontal, vertical down and flat)
8 - Since this last digit is sometimes combined with the third number to derive information about an electrode, it can cause some confusion. The goal here is to communicate the flux/deoxiders and other ingredients used in the electrode coating. Coatings are designed for both the polarity of the power source and the welding position. Thus, you have to read the two digits together to know what's in the coating. The chart below gives you the recipe for all- position (1) and horizontal/flat (2) welding, along with the current types/polarties available for each rod designation.
On occasion, you'll also come across numbers like E-8018-C1. The suffix at the end usually indicates alloys added to the weld metal. The most common are molybdenum, chromium (combined to form "chomoly"), and nickel. Here are a few examples:
A1 - Carbon Moly
B1 - 1/2 CR, 1/2 MO
B2 - 1-1/4 CR, 1/2 MO
B3 - 1-1/4 CR, 1 MO
C1 - 2-1/2 Nickel
C2 - 3-1/2 Nickel
C3 - 1 Nickel
D1 - 1-1/2 MN, 1/4 MO
D2 - 1 MN, 1/4MO
M - conforms to military specs.
Here's another chart that describes six standard electrodes used for welding mild steel:
Notice how the ingredients in the coating of the rod affect how the filler metal gets deposited in the weld, as well as the polarity required from the power source. (The weld metal in the center of the rod is the same for all these products.)
The welding trade also divides stick electrodes into four general groups, based on chemical additives that have a desired effect on the weld pool:
Fast Freeze (0,1) - Good for overhead welding
Fill Freeze (2,3,4)
Fast Fill (21-27) - Limited to flat and horizontal position
Low Hydrogen (18, 28) - Limits porosity
These four categories are not easy for welding students to grasp at first, due perhaps to the lack of creativity in the naming convention. Yet it helps to become familiar with the terminology, and to remember that not all stick rods work for every situation.
Another confusing concept concerns polarity in welding. Notice in the two charts above that there are three choices available under "Current". AC represents the familiar alternating current, which is an acceptable option for all the electrodes listed there, except E-6010. The other two options, which pertain to DC (direct current), require a little explanation.
DCEP or DC+ "Electrode Positive" - This is also known as "reverse polarity"and is the choice for most stick welding. Although electrons inevitably flow through a circuit from its negative to positive sides, you can effectively reverse the current by switching the connections of your electrode holder and the work clamp. (On most industrial sticking welding machines nowadays, DCEP is either the default setting or accomplished by manipulating the controls to choose AC, DCEP or DCEN.
The objective for using DCEP is to put 70% of the heat (that's generated by the electric arc) at the tip of the electrode, which can melt it with a vengeance into the joint. The other 30% ends up dispersed around the work piece.
DCEN or DC- "Electrode Negative" - This is "straight polarity". Now 70% of the heat gets focussed on the work plates, and only 30% reaches the tip of the electrode. This situation is desirable when working with thin metal stock or a joint that doesn't require deep penetration. DCEN is also the choice of polarity for most TIG welding on metals other than aluminum, which prefers AC as its current polarity.
Beware, there's a lot of confusion about DCEN and DCEP. If you ever have questions, consult a reputable source, like the Miller or Lincoln Electric websites, or read a textbook on the subject. As a general rule of thumb, TIG likes DCEN, while Stick Welding likes DCEP.
Although stick welding is primarily used on carbon steel, you can purchase rods to weld some stainless steels and aluminum. The most common rod for stainless steel is 308, which works for base metals that are classified as either 304 or 308 using the AISI standard. (Stainless steels, incidentally, are classified using three-digit numbers, falling mostly in the 200, 300 and 400 range.) A common aluminum stick rod is 4043. (Aluminum classifications are identified by AISI 4000, 5000 and 6000 series numbers.)
Aluminum stick welding with an E4043 rod.
Once a welder has decided on an acceptable electrode, that leaves two more decisions. What diameter of electrode should be used? And what current range is right for this diameter?
Consumeable sellers usually provide a chart that lists allowable amperage, based on rod diameter. Here's an example:
Here's a more general range of current settings for a variety of stick welding rods. Notice that the table recommends less current when welding in the vertical or overhead position.
As for choosing the right diameter of the rod, that depends on the type of joint you're creating and the thickness of the base metal. (The coating around the electrode doesn't count as part of its diameter, just the weld metal inside.) Since larger-diameter electrodes produce larger-sized welds, you wouldn't want to use a 3/16" rod on sheet metal that's 1/8" thick. Lap joints, as you'll learn in school, require a lot less penetration and weld metal buildup than a beveled groove joint. Finally, heat is a major concern when welding metals other than carbon steel, so the allowable current range factors heavily into choosing the right rod for stainless steel, other alloyed metals and aluminum.
Check out the Lincoln Electric stick electrode guide (PDF) to learn more about brands, specifications and other characteristics.Care and Storage of Electrodes
Low-hydrogen stick electrodes (e.g. E-7018) require a special storage environment because of their coatings. Welders have to keep these rods dry, since moisture (aka H20) contains hydrogen.
So long as the rods remain sealed inside the box where they were originally packed, no special handling is required. But once the seal is broken, extra care must be taken. In a warehouse, or out in the field, it's common practice to warm batches of them in a rod oven at 250 degrees about 30 minutes to an hour before use. A welder fetches a handful of warm rods at a time, places them in an electrode pouch, then goes off to his work location. Rods shouldn't be heated more than three times in an oven, so it's good practice to estimate your needs wisely on a daily basis.
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Common Questions About Stick Electrodes
AWS Classifications Explained
Factors for Selecting the Right Stick Electrode
Intro to Consumeable Rods
Storage Requirements for Stick Electrodes
Examining the finer points of 6010, 6011, and 7018 TheFabricator.com
Stick welding aluminum