Welding electrodes, diameters, types and brands

Welding electrodes are metal rods that have a special coating that protects the rod from heating along its entire length and the combustion of which contributes to a higher-quality weld.

The history of welding electrodes goes back to the distant 19th century.

Welding electrodes were first used by Professor Petrov in 1802.

In the early 20th century, welding electrodes for manual welding were developed. This was followed by the development of welding coatings and materials. Today, as technology improves, craftsmen strive to ensure the quality of their work, so the development of welding electrodes continues to evolve. As a result, today we have a huge variety of electrodes designed specifically for specific tasks and for working with specific alloys/metals under specific conditions.

Welding electrodes are made of conductive material to ensure good electrical conductivity between the electrode and the workpiece. This is necessary to create a uniform and powerful electric arc, which heats the metal, enabling welding. Electrodes are typically made from special welding wire, which can vary in alloy composition, to ensure high-quality welding of parts made of various steels and alloys.

The most important and most popular material for which welding electrodes are used is carbon steel.

Welding electrodes: types and coatings

There are certain coatings used in the creation of the electrode:

Stabilizing coatings. These coatings are applied in a thin layer. Typically, these electrodes are intended for manual welding;
Protective. These coatings are applied in a thick layer and typically consist of several elements;
Magnetic. These coatings are applied through electromagnetic interaction, typically during the welding process itself. However, electrode coatings can vary.

The most popular coatings are presented below:

Rutile. These coatings appeared when rutile began to be mined. However, along with rutile, certain other elements are added, such as calcium or magnesium carbonate;
Calcium fluoride. These coatings contain calcium carbonate;
Organic coatings. Typically, the main component is organic matter. Coatings can be applied in either thin or thick layers, depending on the material.

Welding electrode diameters

High-quality metal welding with electrodes requires selecting the right electrodes for the specific task at hand. Key factors that influence electrode selection include:

thickness of the metal of the parts being welded;
composition of the alloys from which the parts are made;
conditions in which work must be carried out (under water, etc.).

Although there are a number of other factors, these three are generally the only ones used in practice.

So, when determining which welding electrodes to use for welding, it's important to understand that the main differentiating factors are the diameter and material (the metal the electrodes are made of). We'll discuss the electrode metal below, but for now, we'd like to focus on the choice of diameters.

Electrode diameters play a key role in selecting the welding current. It's worth noting that the electrode diameter is the diameter of the metal wire itself, excluding the coating. This approach is regulated by GOST 9466-75.

Overall, the electrode range includes diameters from 1 mm to 12 mm, with individual offerings spaced at 1 mm or 0.5 mm increments. Accordingly, electrodes are available in the following diameters: 1 mm, 1.6 mm, 2 mm, 2.5 mm, and then in 1 mm increments, i.e., 3, 4, 5, 7, and 12 mm.

Electrode diameter and welding current

It's logical to conclude that as the electrode diameter increases, the welding current must also increase. However, this increase isn't proportional, and operating currents are most often selected individually, directly on-site, with nominal values selected to begin with. This approach is driven by the need to vary the current based on factors such as:

contamination of the metal (in practice, it is not always possible to work with well-cleaned workpieces);
welding conditions (humidity, ambient temperature, etc.);
alloys that have to be worked with (most electrodes for alloy steels are “universal” in the sense that they can be used to work with alloys of different compositions (different percentages of inclusion of alloying elements));
thickness of metal.

There are approximate values that should be used as a guide when determining the operating current:

Welding electrodes 1 mm – workpiece metal 1-1.5 mm, at a current of 20-25 A;
Welding electrodes 1.6 mm - in accordance with GOST 9466-75 for low-carbon and alloy steel, are produced in two sizes 200 or 250 mm, used for working with metals with a thickness of 1 to 2 mm with a current of 25-50 A;
Welding electrodes 2 mm - according to GOST 9466-75 for low-carbon and alloy steel are manufactured in a length of 250 mm, a length of 300 mm is also allowed, the thickness of the metals being welded is from 1 to 2 mm, current strength is 50-70 A;
Welding electrodes 2.5 mm - according to GOST 9466-75 for low-carbon and alloy steel are produced in lengths of 250-300 mm, a length of 350 mm is also allowed, the thickness of the metals being welded is from 1 to 3 mm, current strength is 70-100 A;
Welding electrodes 3 mm - the most widely used electrode diameter, in accordance with GOST 9466-75 for low-carbon and alloy steel, are produced in three sizes 300, 350 and 450 mm, designed for working with metals with a thickness of 2 to 5 mm with a current of 70-140 A;
4 mm welding electrodes are a widely used diameter, suitable for both professional and household welding equipment. Manufactured in accordance with GOST 9466-75 in two sizes: 350 and 450 mm, for all types of steel and metals 2 to 10 mm thick, with a current rating of 100-220 A.
5 mm welding electrodes – electrodes of this diameter require sufficiently powerful welding equipment. In accordance with GOST 9466-75, they are manufactured in lengths of 450 mm for low-carbon and alloy steel, while a length of 350 mm is also permitted for high-alloy steel. They are designed for working with metals 4 to 15 mm thick with a current of 150-280 A.
6 mm welding electrodes – designed for use with professional welding equipment. According to GOST 9466-75, they are available in 450 mm lengths for low-carbon and alloy steel, while 350 mm is also acceptable for high-alloy steel. They are designed for working with metals 4 to 15 mm thick and with a current of 230-370 A.
Welding electrodes, 8-12 mm, for use on high-performance industrial equipment. In accordance with GOST 9466-75, they are available in 450 mm lengths for low-carbon and alloy steel, while a 350 mm length is also acceptable for high-alloy steel. They are designed for working with metals thicker than 8 mm and with a current of 450 A.

It's important to note that the values provided are approximate, and a more precise current determination is made on-site. Moreover, current at a given diameter can vary significantly for different brands of electrodes. For example, for 3mm UONI 13/55 electrodes, the current ranges from 70-100 A, while for MR electrodes of the same diameter, it ranges from 80-140 A. Therefore, the manufacturer usually specifies the current value on the packaging. If the packaging is unavailable or you can't even determine the manufacturer's product, you can confidently use the average values described above and adjust them as needed for the best results.

Welding electrodes and wires