Whether you are a professional welder or a DIY enthusiast, you should know what welding electrodes are and their relative pros and cons.
So what are welding electrodes? Welding electrodes are lengths of wire that are connected with your welding machine to create an electric arc. Current passes through this wire to produce an arc, which generates a lot of heat to melt and fuse metal for welding.
The main types are:
- Consumable
- Non-consumable
This article will help you to differentiate between different kinds of welding electrodes and give you a good idea of their strengths and weaknesses so that you can determine the best choice for your welding applications. Read on to find out more.
Different welding electrodes
The rods used for MIG and stick welding are examples of consumable electrodes. They have filler material, which melts to create weld joints.
TIG welding, on the other hand, employs non-consumable electrodes. These electrodes consist mostly of tungsten, which does not melt (unlike consumable electrodes) due to its high melting point. It merely supplies an electric arc for welding. The filler material is provided using a wire that is manually fed.
Hence, the main difference between the two is that consumable electrodes melt, whereas non-consumable electrodes do not.
The two categories have several types of electrodes, as well.
Consumable electrodes
Consumable electrodes are the key to stick, MIG, and flux-cored arc welding. The consumable electrodes used for stick welding are called stick electrodes. These include heavy-coated electrodes, shielded arc, and light coated electrodes.
Light coated electrodes
As the name implies, light coated electrodes have a thin coating on their surface, which is applied by methods like spraying and brushing.
These electrodes and their coatings are made from several different materials. The filler material bears a lot of similarity to the base metal that is being welded.
The light coating also serves another vital purpose. This coating reduces impurities, such as sulfur and oxide, to give a better quality weld. It also allows more consistent melting of the filler material so that you can create a smooth looking and reliable weld bead.
Since the coating is thin, the slag produced is not too thick. Shielded arc electrodes bear some similarity to light coated electrodes. The main difference is that they have a thicker coating. These heavy-duty electrodes are suitable for more demanding welding applications, for instance, the welding of cast iron.
Bare electrodes
Using bare electrodes can be tricky because the arc is somewhat unstable and difficult to control. The light coating increases the stability of the electric arc, thereby making it easier for you to manage. Bare electrodes have limited applications. For example, they are used for welding manganese steel.
Shielded arc electrodes
Shielded arc electrodes have three different types of coatings, which serve different purposes. One kind of coating contains cellulose, and it uses a protective gas layer to protect the weld region. The second type of coating has minerals that produce slag. The third kind of coating has a combination of minerals and cellulose.
Shielded arc electrodes generate a protective gas layer, which forms an effective barrier to shield the hot weld zone from contamination and corrosion by the surrounding air. This results in stronger and more reliable welds. The heated weld zone must be kept safe from atmospheric gases like nitrogen and oxygen, which react with the high-temperature metal to produce brittle, porous, and weak welds.
Shielded arc electrodes minimize sulfur, oxides, and other types of impurities within the base metal to give regular, smooth, and clean welds. These coated electrodes also produce a more stable electric arc compared to bare electrodes, which makes welding more manageable and reduces spattering.
Shielded arc electrodes also produce slag due to the mineral coating. This slag appears to be a hassle to remove, but it serves a beneficial purpose. It cools much more slowly as compared to shielded arc electrodes. This process draws out impurities and sends them towards the surface. Consequently, you will get high-quality welds that are clean, durable, and strong.
Non-consumable electrodes
Non-consumable electrodes are simpler to understand not only because they do not melt but also because there are only two types.
Carbon electrodes
The first kind is the carbon electrode that is used for both cutting and welding. This electrode is made out of carbon graphite. It may be coated with a copper layer or left bare.
The American Welding Society has not issued any specifications for this kind of electrode. However, military specifications do exist for carbon electrodes.
Tungsten electrodes and their different kinds
The second kind of non-consumable electrode is the tungsten electrode, which is used for TIG welding. These electrodes consist of pure tungsten (which have green markings), tungsten-containing 0.3 to 0.5 percent zirconium (these have brown markings), tungsten with 2 percent thorium (which have red markings) and tungsten-containing 1 percent thorium (which has yellow markings).
Non-consumable electrodes made from pure tungsten, have limited use, and are suitable for light welding jobs. There are two reasons for this. First, pure tungsten does not possess the durability and strength of tungsten alloys. Second, pure tungsten can suffer problems with high current.
Tungsten electrodes with 0.3 to 0.5 percent zirconium offer excellent results with alternating current. They are an improvement over pure tungsten, but not as good as tungsten electrode with thorium content.
Tungsten electrodes with 1-2% thorium content are some of the most widely used non-consumable electrodes since they last longer and have a higher resistance than other kinds of tungsten electrodes. They can be used for higher currents compared to pure tungsten electrodes. These electrodes also provide greater arc control and are easier to start.
While using a tungsten electrode, it is better to use the maximum allowable current if they have a plain cylindrical or else it becomes difficult to control the arc and sustain it.
For better arc control and stability, you should grind the tips of these electrodes to a point, that is, you need to make the tips conical. If you do this, you will have to select touch-starting instead of DC welding machines. Remember that tungsten electrodes with thorium and zirconium will have improved durability than pure tungsten electrodes if you opt for tapered electrodes using touch-start.
How to read the code on stick electrodes
Now that you have a good understanding of the basics, it is time to delve deeper into welding rod classification.
This classification for stick electrodes considers different factors like iron powder percentage, most suitable welding position, tensile strength, coating material, and diameter.
Do not use consumable electrodes that are thicker than the metal section that you are welding. The most commonly used electrode diameter is 3/32 in. However, some applications require electrode diameters that can be as much as five times larger or just 1/16 in.
The tensile strength is the maximum force that the weld can tolerate. To make a durable and secure weld, you need to use an electrode that has stronger filler material than the base metal. If the filler material is weaker than the base metal, then the weld joint will become a weak point that can break easily.
The electrode’s iron powder percentage also matters since it will be converted to steel when molten by the welding heat. A higher iron powder percentage means that each electrode can provide you with more filler material to weld more parts. However, you should bear in mind that the iron percentage is unlikely to exceed 60 percent.
Having understood these properties, you can now consider the classification code for these electrodes.
For instance, you may come across E6010. The ‘E’ refers to the fact that this is an electrode. The first two digits that follow ‘E’ indicate the tensile strength. ‘60’ here means that the tensile strength is 60,000 pounds per square inch.
So you have to add four zeros to these two digits to determine the tensile strength of the electrode. The number 70, therefore, implies a tensile strength of 70,000 pounds per square inch.
If there are five digits, then the first three digits following ‘E’ refer to the tensile strength.
The second last digit indicates the position for which you can utilize the electrode. ‘1’ means that you can use the electrode for all positions – overhead, horizontal, vertical, and flat. ‘2’ means that the electrode is suitable for horizontal and flat positions only.
The last digit, in conjunction with the penultimate digit, tells you about the coating. This information will help you to decide the welding current. The electrode manufacturer will provide a table listing the current settings for different coatings according to the last two digits.
What are welding electrodes made of?
A welding electrode is created from two components: the true metal and also the flux coating. The alloy may differ from mild-steel, cast iron, stainless steel, high-tensile steel, bronze, aluminum, aluminum, or aluminum.
What do the numbers mean on a 7018 welding rod?
Within this classification procedure, the very first 2 or 3 numbers suggest the tensile toughness of the bonded product, which can be measured in kpi or kilo-pounds per square inch. In E7018, 70 symbolizes 70,000 psi or 70 kpi. 1: the 3rd figure suggests the welding position.
What is a 6012 welding rod used for?
Utilize 6012 welding sticks to join an open connection between two joints. Professional welders utilize 6012 electrodes at the flat position because of its own rapid, high-current fillet welds.