If you take an interest in welding or you are a professional welder, you must have knowledge about welding electrodes and everything associated with it. So, this guide might be a help for you as here we will find out all the potential answers to your questions.
- What Do You Mean By Welding Electrodes?
- What Are Covered Welding Electrodes?
- Understanding The Classification
- Classification System For Submerged Arc Electrodes
- What Are The Types Of Coatings?
- How To Store?
- What Are The Different Types Of Electrodes?
- What Are The Electrode Defects & Their Effects?
- Understanding Deposition Rates
- Non-consumable Electrodes
What Do You Mean By Welding Electrodes?
Electrodes are coated metal wires. These are generally made of materials that have the same composition as welded metals. There are a range of factors that you require to keep in mind while choosing the correct electrode for every project.
These are the lengths of wires which are connected to the welding machine for creating electric arcs. Current generally passes through the wire to produce an arc that generates heat for melting and fusing metal required in the welding process.
- SMAW or the stick electrodes are generally consumable. This means that they are a huge part of welding and can be referred to as welding rods or filler electrodes.
- TIG filler rod is another popular option which is the optional filler material. This is generally used for fusing two different pieces of stock as composites.
- TIG tungsten electrodes do not melt, so they are a non-consumable option. They take part in the welding when there is a need for a welding rod.
- MIG welding electrodes are another, which is the Fed wire. It is also referred to as the MIG wire.
Proper selection of electrodes is essential for the welding strength, easy cleanup, minimizing spatter and beat quality. There is a need for the electrodes to store carefully and in an area that is moisture free. After removing the package, make sure to follow the direction provided by the manufacturer to avoid any kind of external damage.
What Are Covered Welding Electrodes?
When you expose the molten metal to the air, it has the tendency to absorb nitrogen and oxygen and become brittle. It is adversely affected when exposed to air. So, a thin layer of slag cover is required to protect the molten metal or solidify the welded metal from changes when coming into contact with the atmosphere. Using electrode coating, you can easily obtain this cover.
The welded electrode coating composition plays a massive role in determining the specifications of an electrode, the composition of welded metal, and its usability. The coating formulation is strongly dependent on the basic principles of physics, chemistry, and metallurgy. The coating is essential as it provides a protective layer to the metal. It prevents stabilizing the arc, damage, and improving the weld in different ways.
Here Are Some Of The Most Common Ways How It Improves Welding.
- Stable welding arc
- Tough and strong coating
- Increase the disposition rate
- Easy slag removal
- Smooth metal surface and even edges
- Control over penetration
It is easy to classify and group the metal arc electrodes as thinly coated or bare electrodes and heavily coated or shielded arc electrodes. Covered electrons are a popular filler metal that is generally used for arc welding. It has the composition to cover electrodes that determines its usability, specifications, and the deposited weld metal.
The electrode type that you have used is based on particular properties needed for weld deposition. Some of these properties include high tensile strength, ductility, corrosion resistance, base metal type for welding, position, polarity, and current requirements for the process.
Understanding The Classification
For welding electrodes, most of the welding societies in America have adopted the classification number series of the American Welding Society. This is commonly followed by most of the welding industries.
Check out the following setup for the steel electrode identification system.
- E Denotes that the electrode is specifically for arc welding.
- The initial two or three digits denote its tensile strength. This is the Material’s resistance to the forces that try to pull it apart. It is made of thousand pounds of deposited metal per square inch.
- The third or fourth digit denotes the welding position. 0 is an indication of the classification not being used, 1 denotes all positions, 2 is for horizontal or flat positions, and 3 is only for flat positions.
- The fourth and fifth digit denotes the electrode type used for electrode coating. It is also an indication of the type of power supply used, whether it is reverse or straight polarity or direct or alternating current.
- The coating type, polarity position, and welding current are designated with the classification’s fourth digit.
For example, if you take the number E6010, it will denote that it is an arc welding electrode that has 60,000 psi tensile strength and minimum stress. It can be used in different positions, and the power supply is direct current and reverse polarity.
Classification System For Submerged Arc Electrodes
Understanding the identity system for the solid bare carbon steel can be done through the following ways.
- The letter E in the prefix is mostly used for an indication of an electrode. It is then followed by the letter that denotes the manganese level. This will have H for high manganese, M for medium, and L for low. Followed by this, it will find a number that indicates the average carbon amount, which is either denoted in points or percent. Some of the wire composition is completely identical to the wires in the gas metal specifications.
- American welding society specifications have named the electrode wire that has been used for submerged arc welding. It is “Bare Mild Steel Electrodes and Fluxes for Submerged Arc Welding.” The specifications will provide weld deposit chemistry and wire composition depending on the flux used. Its specifications provide electrode wire composition. When you use specific submerged arc fluxes on these electrodes and are welded in different procedures, it can meet mechanical properties for the deposited weld metal.
- Reds are generally used for welding oxy fuel gas and filler. You will find its prefix letter R and then G, which denotes the rod that is most commonly used for gas welding. After these letters, you will find two digits which might be 65, 60, or 45. This denotes the approx tensile strength required in 1000 PSI.
- In the case of non-ferrous filler metals, most commonly, you will find the prefixes RB, R, or E. After these letters, you can find chemical symbols of the metals. Most commonly, the initials of the elements will be provided. In case more than a single alloy is used, and similar elements are included, you will find the suffix letter or any number added to it.
- The specifications of the American Welding Society are mostly used for identifying electrode wires and bare welding rods. You will also find military specifications like MIL – E or – R types. Federal specifications are AMS and QQ – R type. Specific identification is required for particular filler metals.
One of the vital aspects of solid welding electrode rods and wires is the composition provided by specifications. All the specifications will provide knowledge about the composition limits for different wires and the need for mechanical properties.
You might find copper flaking off with the copper-plated wires in the feed role mechanism. It can be a huge problem. This might plug the contact tapes or liners. Using light copper coating is hence a desirable approach. There is a need for the electrode wire surface to be free from dust and other compounds. You can simply use white cleaning tissue to check and pull throughout the length of the wire. Remember, too much dust can’t log liners, create erratic operation, and can reduce the ability to pick up current from the tip.
The strength or temperature of the wire can be easily checked by using a testing machine. Higher-strength wires will feed through cables and guns in a much better way. However, wires with minimum tensile strength must have the specifications of 140, 000PSI.
You can find different packages of electrode wires. They generally range from small spools that are used on the spool guns to medium spools for metal arc welding. You can place the electrode coils on reels that take part in welding equipment. The range of reels you can find is hundreds of pounds. You can find the electrode wire and pay-off packs or drum packs where most of these wires are properly laid in round containers and are pulled using an automatic wire feeder.
Check The Following Table.
|CHARACTERISTICS OF ELECTRODES
|Tensile Strength (PSI)
|High Cellulose Sodium
|High Cellulose Potassium
|High Titania Sodium
|High Titania Potassium
|DCEP DCEN AC
|Iron Powder Low Hydrogen
|Shallow – Medium
|Iron Powder Low Hydrogen
|Shallow – Medium
What Are The Types Of Coatings?
There are almost 6 to 12 ingredients used for coating the welding electrodes. These are generally used on welding low and mild alloy steels.
- Titanium dioxide is used as it helps to create quick freezing but highly fluid slag to encourage arc ionization.
- Cellulose provides a gaseous shield combined with the reducing agent, whereas Celulose disintegration produces a shield of gas around the arc.
- Ferrosilicon and ferromanganese can be beneficial for oxidizing molten weld metal and also supplementing manganese and silicon content.
- Metal carbonate helps to adjust slag basicity and provides the reducing atmosphere required.
- Calcium fluoride produces gas shielding for arc protection and fluidity, adjusting the slag basicity and metal oxide solubility.
- Gums and clays offer elasticity to the plastic-coated material. It also gives strength to the entire coating.
- Mineral silicate provides strength and slag to the cover of electrodes.
- Manganese or iron oxide helps to adjust the fluidity and properties of slag along with stabilizing the arc.
- Alloy metals like chromium, molybdenum, and nickel offer more alloy content deposition on the welded metal.
There are several other coating types other than the above-mentioned ones. Most of them are a combination of the mentioned types. However, professionals must make the combination for any special application, like nonferrous metals, cast iron welding, and hard surfaces.
How To Store?
You must keep the electrodes dry. Remember that moisture can deteriorate the characteristics of the coating and can cause splattering, cracks, and porosity in the welded area. When you expose electrodes to damp air for over three hours, make sure that you dry them by heating them at 500°F for at least two hours.
After properly drying the electrodes, choose a proper container that is moisture-proof to store them. If you bend them, it can lead to getting lose or breaking the core wire. You must not use electrodes if its core wire has been exposed.
However, if you check the classification and you find the suffix R, it means that the electrode has improved moisture resistance.
What Are The Different Types Of Electrodes?
1. Bare Electrodes
Wire compositions are used to create bare welding electrodes for particular applications. These specific electrodes do not have any coatings unless needed for wire drawing. These coatings provide a slight stabilizing effect, but apart from this, there are no such consequences. These are mostly used for welding manganese steel and several other purposes where coated electrodes are undesirable.
2. Light Coated Electrodes
There is a certain composition in light-coated electrodes. A light coating is generally applied on its surface by spraying, dipping, washing, brushing, wiping, or tumbling. Such coatings increase the arc steam characteristics.
The following are the functions served by this coating:
- It reduces or dissolves the impurities like phosphorus, sulfur, and oxides.
- It alters the surface tension of molten metal to make sure that the end of the metal is frequent and smaller. This enables improved and uniform flow of molten metals.
- It improves the stability of the arc by introducing readily ionized metal into the arc stream.
- Some light coatings might produce slag. It is thin slag and would not act similarly to a shielded electrode.
- Shielded Arc or Heavy Coated Electrodes
Heavy-coated or shielded arc electron has a certain composition. This needs to be maintained for the coating, which is applied through extrusion or dipping.
There are three common types followed in manufacturing electrodes:
- Mineral coating
- Cellulose coating
- Combination of Cellulose and mineral coating
Cellulose coatings consist of soluble cotton or different other forms of Cellulose that have a tiny amount of sodium, titanium, potassium, and other materials in some cases. It has the ability to produce gaseous zones across the arc and welded zone to protect the molten metal.
The mineral coating is generally composed of metallic oxide, sodium silicate, clay, and several other inorganic substances. It can form slag deposition.
3. Functions of Shielded Arc or Heavy Coated Electrodes
The welded electrons have the ability to produce reducing gases that shield the arc. It can be helpful as it prevents metal contamination by getting exposed to nitrogen or atmospheric oxygen. As oxygen combines with molten metal, it generally removes the elements and results in porosity. Nitrogen can cause low ductility, brittleness, and poor corrosion resistance with low strength.
It can reduce impurities like phosphorus, sulfur, and oxide so that the impurities do not make any impairment to the welding deposit. The use of certain substances increases stability. It eliminates fluctuation, and hence the arc is maintained correctly without splattering.
It has a coating that has silicate, which forms a slag on the base metal and molten weld. As the slag starts cooling at a very slow rate, it allows the cooling of metal and slows solidifying by holding heat. The slow solidification process in metal eliminates any chances of gas entrapment and permits the floating of impurities on the surface.
By incorporating the alloy materials, you can modify physical characteristics. It offers improved quality of welded metal and enhances the speed.
4. Tungsten Electrodes
There are three different types of TIG welding for non-consumable electrodes. You can easily identify tungsten electrons through the mark or paint. The following can help in the identification process.
Brown: Contains 0.3 – 0.5% zirconium.
Red: Contains 2% thorium.
Green: Pure tungsten.
Yellow: Contains 1% thorium.
Pure tungsten electrodes are mostly used on lesser welding operations compared to alloyed tungsten. These electrodes have a lesser capacity to carry current and less resistance to contamination.
Tungsten electrodes have 0.3 to 0.5% of zirconium. It is commonly in between thoriated tungsten and Pure tungsten electrodes when it comes to performance.
Thoriated tungsten is considered way superior to pure electrodes as they have improved arc stability, higher electron output, longer life, better capacity to carry current and improved resistance to contamination.
5. Direct Current Arc Welding Electrodes
You must follow the manufacturer’s recommendation when you choose a particular kind of welding electrode. In common, the direct shielded electrodes are mostly designed for straight or reverse polarity or even both. Even where not all, most of the direct current electrodes use alternating current.
Several kinds of covers use direct currents like non-ferrous, oil alloy steel, and bare electrodes. You will also find manufacturer recommendations, including the base metal type that is suitable for the particular electrode, specific conditions, and other corrections in case of poor fit-ups.
In most of the cases, you will get less penetration when you choose electrodes of straight polarity compared to reverse polarity. This is the reason why it offers improved welding speed. With both types, you will find excellent penetration when provided with arc manipulation and welding conditions.
6. Alternating Current Arc Welding Electrodes
Coated electrodes are great when used with alternating or direct current. Alternating current is desirable when you need to perform welding in restricted areas, or you’re using high current for the thicker section as it reduces the arc blow. It generally results in slag inclusion, less weld fusion, and blowholes.
You must use alternating-current and carbon art procedures and atomic hydrogen welding. This allows producing a uniform welding rate and proper electrode consumption.
What Are The Electrode Defects & Their Effects?
In case you find oxides or elements present in the coating of an electrode, you must know that it will directly affect the arc stability. When it comes to bare electrodes, uniformity and composition are one of the most vital factors in maintaining arc stability. Heavy or thinly coated electrodes will remove any effects from the defective wire.
Aluminum oxide or aluminum, silicon oxide, silicon, and iron sulfate are considered very unstable. Whereas calcium oxide, manganese oxide, and iron oxide have the ability to stabilize the weld.
If sulfur or phosphorus is available over 0.04%, it can affect the welded metal as they transfer from electrode to molten metal. Phosphorus can result in brittleness, grain growth, and cold shortness. Such defects can improve magnitude. Sulfur generally acts as slag and causes brittleness. Manganese can encourage the proper formation of welds.
Understanding Deposition Rates
Different electrodes have various disposition rates because of the composition of the coating. The iron powder, when used in electrodes in the coating, will have a greater deposition rate. The percentage in the coating is somewhere between 10 to 50%.
The percentage is associated with the American welding society’s requirement specifications. However, the European method is a little bit different.
- 30% of iron powder in US standard can produce 100 – 110% deposition with European formula.
- 50% iron power with US standard can produce 150% deposition with European formula.
You will find two different varieties of electrons for non-consumable welding.
- Carbon electrode is one of them, which is a non-filler metal electrode that is generally used for cutting or arc welding. It is composed of carbon graphite rods that might not or might be coated with copper or any other coatings.
- Tungsten electrode is another type that is non-filler metal. These are most commonly used for cutting or arc welding. It is principally made of tungsten.
1. Carbon Electrodes
There are no specifications provided by the American Welding Society for the carbon welding electrode. However, there are military specifications entitled “Electrodes Cutting and Welding Carbon-Graphite Uncoated and Copper Coated.”
This particular specification offers a classification system depending on three different grades like uncoated, copper-coated, and plain. You will get diameter information, needs according to size tolerance, and length information. You will also be able to understand sampling, quality assurance, and other tests. Some of the most common applications comprise twin carbon welding, carbon arc welding, air carbon cutting, and carbon cutting.
2. Stick Electrodes
- You will be able to differentiate stick welding electrodes by the following methods.
- Materials: The stick welding electrodes are mostly available in high-carbon steel, cast iron, special alloys, iron-free and mild steel.
- Size: Some of the most common sizes available are 5/6, 1/4, 7/32, 3/16, 1/8, 5/6, 1/16, and 3/32. There is a need for the core wire to be a bit narrow compared to welded materials.
- Strength: It is generally focused on tensile strength. Every welding will be stronger compared to the welded metals. Hence, the electrode material must be stronger as well.
- Iron powder mix: When present in flux, it will improve the molten metal present in the weld.
- Welding positions: You can use a range of electrodes for the different welding positions.
- Soft arc designation: It is definitely a choice for metals or thinner metals that mostly do not have a proper gap and the perfect fit.
Welding rods or welding electrodes are mostly manufactured from compositions and materials that are almost similar to welded metals. However, the welding rod choice will be completely dependent on a range of factors for every project.
The selection of electrodes strongly depends on bead quality, easy cleanup, minimal spatter, and welding strength. MIG welding or arc welding electrodes are consumable as they are a part of the process. TIG electrodes are not a part of the process and do not melt; hence they are non-consumable.