What are the thickness of electrodes?

Electrodes for arc welding

Electrode coatings consist of slag-forming, gas-forming, deoxidizing, alloying, stabilizing and binding (adhesive) components.

Slag-forming components protect the molten metal from exposure to oxygen and nitrogen in the air and partially refine (purify) it. They form slag shells around drops of electrode metal passing through the arc gap, and a slag coating on the surface of the weld metal.

Slag-forming components reduce the cooling rate of the metal and contribute to the release of non-metallic inclusions from it.

Slag-forming components may include titanium concentrate, manganese ore, feldspar, kaolin, chalk, marble, quartz sand, dolomite, as well as substances that increase the stability of the arc.

During combustion, gas-forming components create a gas protection that protects the molten metal from oxygen and nitrogen in the air. Gas-forming components consist of wood flour, cotton yarn, starch, food flour, dextrin and cellulose.

Deoxidizing components are necessary to deoxidize the molten metal of the weld pool. These include elements that have a greater affinity for oxygen than iron, for example manganese, silicon, titanium, aluminum, etc. Most deoxidizers are introduced into the electrode coating in the form of ferroalloys.

Alloying components are necessary in the coating to give the weld metal special properties: heat resistance, wear resistance, corrosion resistance and increased mechanical properties. Alloying elements are manganese, chromium, titanium, vanadium, molybdenum, nickel, tungsten and some other elements.

Stabilizing constituents are those elements that have a low ionization potential, such as potassium, sodium and calcium.

Binding (adhesive) components are used to bind the components of the coating to each other and to the electrode rod. They use potassium or sodium liquid glass, dextrin, gelatin and others. The main binder is liquid glass.

All coatings must meet the following requirements:

• ensure stable arc burning;
• the physical properties of the slag formed during melting of the electrode should ensure normal formation of the seam and convenient manipulation of the electrode;
• there should be no reactions between slags, gases and metal that could cause the formation of pores in welds;
• coating materials must be well crushed and not react with liquid glass or with each other in a batch;
• the composition of the coatings must ensure acceptable sanitary and hygienic working conditions during the manufacture of electrodes and during their combustion.

An electrode, consisting of an electrode rod and a coating, when melted, forms molten metal and slag. The slag must have certain physical and chemical properties.

The physical properties of slag include melting point, solidification temperature range, heat capacity, heat content, viscosity, ability to dissolve oxides, sulfides, etc., density, gas permeability and coefficients of linear and volumetric expansion.

Chemical properties include the ability of slag to deoxidize the molten metal of the weld pool, bind oxides into low-melting compounds, and also alloy the molten metal of the weld pool.

The physical properties of the resulting slags have a significant impact on the welding process and the formation of the weld.

In all electrode coatings, when melting, the density of the slag should be lower than the density of the weld pool metal, which will ensure its floating out of the weld pool.

The temperature range of slag solidification must be lower than the crystallization temperature of the metal of the weld pool, otherwise the slag layer will not allow the gases released from the weld pool to pass through. The slag should cover the entire surface of the weld in an even layer.

The slags formed during the melting of electrode coatings are “long” and “short”. “Long” slags are those that contain a significant amount of silica. Their viscosity increases slowly with decreasing temperature.

Electrodes with coatings that form “long” slags during melting are not suitable for welding in vertical and ceiling planes, since the weld pool remains in a liquid state for a long time.

For welding in all spatial positions, electrodes are used, the coatings of which produce “short” slags when melted; The viscosity of molten slag increases quickly with decreasing temperature, so crystallized slag prevents the weld metal, which is still in liquid form, from draining. “Short” slags produce electrodes with rutile and basic coatings.

Quite good separation of the slag crust from the metal surface is obtained by using slags having a linear expansion coefficient that differs from the linear expansion coefficient of the metal.

Properties of weld metal and technological characteristics of electrodes

Electrodes are characterized by the properties of the metal they deposit, which include: strength, ductility, elongation, impact strength, hardness, corrosion resistance, aging resistance, and during surfacing operations, wear resistance.

Along with the quality of the weld metal obtained by welding with this electrode, its technological properties are also important. The main technological properties of the electrode include its productivity, suitability for welding in various spatial positions, arc stability at direct and alternating current, permissible maximum and minimum arc length, weld shape, deposition, melting and loss coefficients.  

Source: http://build.novosibdom.ru/book/export/html/246

Detailed classification of electrodes, description of markings and areas of application

To form a high-quality weld, it is necessary to choose the right brand of electrodes. This is possible only after familiarization with the main regulatory documents - GOSTs. They describe in detail the characteristics of the electrodes, their operational and technical parameters.

Marking

The electrodes are designed to supply current to the workpiece to form a connecting or repair seam. They differ in material of manufacture, scope of application and specifics of work.

First, you should first understand the features of the classification and labeling of electrodes. If you are able to correctly recognize characters, you can choose the optimal brand.

The marking consists of several sections:

• Strength characteristics, MPa.
• A unique brand is a numerical and letter designation.
• Diameter, mm.
• Scope of application – indication of content types of steels or other metals.
• Coating thickness.
• A special index by which the characteristics of metals can be determined. This is indicated in GOST 10051-75, 10052-75 and 9467-75.
• Operating parameters. Type of coating, spatial position during welding and operating mode of the device - current (direct or alternating), its polarity.

Each of these characteristics indicates the scope of application of the electrode and its performance. Therefore, we need to consider them in more detail.

Purpose

The most important characteristic is the scope of application of the electrodes relative to the welding materials. Some models can successfully form connecting and repair seams in various types of metals. But most often there are restrictions on a certain type.

Welding diagram

The main criterion is the grade of metal and the types of work with it. According to this parameter, there are 5 classes of electrodes, each of which has several types:

• “U” - work with carbon and low-carbon steel grades, which are characterized by a tensile strength of more than 600 MPa.
• “L” - welding work with high-alloy metals and tensile strength over 600 MPa.
• "T" - for heat-resistant steel grades.
• “B” - work with metals with special properties.
• “N” - for surfacing surface layers.

The table shows some brands of electrodes by area of ​​application.

The exact purpose is indicated by the manufacturer on the packaging. But besides this, it is necessary to choose the right model depending on the type of work performed.

This way you can select the optimal brand of consumables for welding.

Coating characteristics

The coating of the electrodes determines the parameters of the future weld. It is applied during the production process and in most cases is necessary to create an optimal gas environment in the bathroom.

There are 5 types of coverage:

1. Rutile.
2. Sour.
3. Basics.
4. Pulp.
5. Mixed type.

Each of them is designed to perform a specific job. They also directly influence the possible welding directions.

In addition, you should pay attention to the thickness of the coating. The volume of the gaseous medium will depend on this. The main characteristic is the ratio of the diameters of the steel rod and the coating.

Electrode position

Before carrying out welding work, it is necessary to correctly select the location of the electrode relative to the part. Not all models can work in a downward or vertical position. This is especially important when welding in hard-to-reach places on steel structures.

You can find out the possible positions from the marking data. They can be either digital or in the form of a graphic image. The latter is convenient, since you can clearly see the recommended position of the electrode relative to the plane of the part.

Welding position

It is worth noting that the labor intensity of the work depends on the welding position. The fewer options there are for a particular brand of electrode, the more difficult it will be to make a weld.

Operating modes of the welding machine

It is important to consider the permissible operating modes of the welding machine. These include the idle value and polarity. It is also necessary to know the permissible deviations of these characteristics.

Knowing the parameters described above, you can select the optimal brand of electrodes, thereby ensuring a high-quality weld. But we must remember that this largely depends on the qualifications and experience of the worker.

Source: https://ismith.ru/welding-equip/klassifikaciya-elektrodov/

Welding electrode coatings for manual arc welding: types, composition, designations

An electrode for manual arc welding is a metal rod with a protective coating. The components of the coating provide protection of the welding zone from oxidation by air and contribute to increased ionization. Coated rods are used for both ferrous and non-ferrous metals, as well as alloys.

Purpose of electrode coating

The main task that manufacturers assign to coating electrodes for manual arc welding is to protect the melting metal . They protect the melting metal from interaction with air, preventing oxidation, and make the finished seam high-quality and durable.

When working with a welding machine, the protective coating creates a shell of slag on droplets of electrode metal moving along the arc gap, as well as on the melting surface of the parts being welded to each other.

A protective layer of slag reduces the speed at which the metal cools and the speed of its hardening , due to which gas and other inclusions have time to escape from it, which negatively affect the strength of the structure. As a rule, protective spraying consists of a whole complex of slag-forming elements, such as kaolin or titanium concentrate.

What functions does high-quality coating provide?

The coating covering the metal rods performs a number of primary and secondary tasks. The most important ones include:

• Protection of the arc itself and the metal in the area of ​​the weld pool from interaction with nitrogen, oxygen, and hydrogen contained in water vapor present in the atmosphere. Coating the rod creates a two-stage protection: vapors of carbon dioxide and carbon oxides enveloping the working area, and a slag film on the surface layer of the molten metal;
• ensuring high-quality crystallization of the seam without the formation of pores, slagging and cracks.

Secondary, but no less important tasks:

• ensuring uninterrupted arc burning in a wide range of operating modes, simplifying the ignition process. Arc stability is achieved due to the presence in the surface layer of the rod of components that are not prone to ionization in a large volume. This helps to increase the number of combustion-stabilizing ions in the arc space;
• removal of oxygen dissolved in it from the metal of the weld pool. To do this, ferroalloys are added to the coating composition, which are lighter and faster than the metal itself and react with oxygen;
• cleaning the weld metal from impurities (refining).

Coating diameter

On sale you can find many brands of electrodes designed for different types of metal and the strength of the expected loads on the future structure. Coated rods have two diameters: the diameter of the electrode itself and the total diameter of the rod and coating. When choosing a suitable option, the diameter is one of the determining factors: the larger it is, the greater the thickness of the metal that can be connected using a rod .

Important! The operating mode of the welding machine is set based on the thickness of the parts being connected and the diameter of the rods. It is important to correctly calculate the current strength, since if the current is too strong, you can simply burn through the metal, and if the current is too weak, it will not be possible to form an arc.

The diameter of the coated rod not only affects the ease of working with the material during welding, but also provides the necessary characteristics of the completed connection and affects the strength of the resulting structure.

So, for example, electrodes marked E42A and E46 are used for welding parts made of low-alloy steels.

The letter “E” in the marking means a piece electrode, widely used for manual arc welding at home.

The number following the letter is the minimum value of the guaranteed tensile strength of the seam. The higher this number, the greater the load the welded part will withstand.

For example, products of the E42 type provide a resistance of at least 42 kgf/mm2, and rods marked E46 provide a resistance of at least 46 kgf/mm2. E42A electrodes are used for metal with similar quality tensile properties, but in conditions where higher parameters of impact strength and relative elongation of the resulting weld are required. The improved characteristics are indicated by the letter “A” in the marking, which indicates the acidic type of coating of the rod.

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Coating thickness

Blue coating of electrode brand MR-3S

In addition to the characteristics of the coating applied to the electrode rod and the diameter of the electrode itself, when selecting materials for welding, they also focus on the thickness of the protective coating.

The coating thickness of the electrode rod is the ratio of the overall diameter (D) and the diameter of the internal rod (d). That is, a thicker electrode may have less coating thickness if it has a lower D/d ratio.

Each diameter of the inner rod has its own coating thickness. There are 4 categories of electrodes, differing in coating thickness:

1. thin or stabilizing electrodes (the letter M is used to designate them) with a ratio of 1.2 or more;
2. middle electrodes (designated C) with a ratio of 1.45 or greater;
3. thick , having a ratio less than or equal to 1.8, which are also called high-quality (marked with the letter D);
4. especially thick electrodes are also included in the quality category and have a diameter ratio of over 1.8 (can be recognized by the letter G in the marking).

The thickness of the coating of high-quality electrodes ranges from 0.5 to 2.5 mm, which is 20-40% of the mass of the internal rod. If we take iron powder into account, the diameter will be 3.5 mm and the mass fraction will be 50%. Such electrodes are used when a high-quality seam that can withstand heavy loads is needed.

Thin or stabilizing electrodes, the coating thickness of which is approximately 0.1-0.3 mm, make the arc burning smooth and continuous, but do not in any way affect the quality characteristics of the deposited steel.

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Types of electrode coating for manual welding

Let's consider what types of electrode coatings there are, their components and how which one is designated. There are four main types of coatings used in the production of welding electrodes:

1. acid coating , designated by the letter A;
2. main (B) coating;
3. cellulose coating (C);
4. rutile (R).

The coating of welding electrodes is selected based on what type of steel is planned to be welded, the load on the structure and other factors.

Sour

The main advantage of acid-type coating is that during welding work, the likelihood of pores forming in the seam area tends to zero , even if the places where the elements are welded to each other are covered with traces of rust or scale. The acidic coating promotes uniform arc burning and easy ignition. This type of electrode is used when the requirements for the finished structure are minimal .

Acid-protected rods work well in both direct and alternating current. The most noticeable disadvantages are welding spatter, toxic fumes, and the risk of hot cracks during welding.

CAREFULLY! Acid coating is toxic when heated!

More information about acid coating >>>
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Basics

Due to the weak oxidation of such a coating, it facilitates easy removal of oxygen from the melting metal. A seam made using an electrode with a basic coating is protected from hot cracks .

An electrode of this type must be calcined before work to eliminate the possibility of pores appearing in the seam.

Due to the difficulty of maintaining an arc, welding with basic-coated electrodes should only be done using a direct current source of reverse polarity (this does not apply to all, but to most brands) .

Electrodes with a basic type of coating are used for welding metal parts made of hardening types of steel that are at risk of cold cracks, as well as for welding elements made of metal with a high percentage of sulfur and phosphorus. “Main” electrodes show high efficiency when welding several layers of structures that require high rigidity.

Read more about this coating and electrodes.

Pulp

The use of products coated with cellulose (marked “C” on the packaging) when working with a welding machine gives good high-quality arc burning, mainly at direct current . This variety is used when welding root seams on main pipelines made of low-carbon steel.

Also, cellulose-coated rods are excellent for single-sided welding with high-quality penetration in the root weld area. The use of rods gives good results when welding is carried out in a vertical position.

It is not recommended to use steel containing a high percentage of carbon and other alloying components for welding. Another disadvantage is the high degree of susceptibility to high temperatures and the likelihood of splashes of molten metal during operation.

More about cellulose electrodes here.

Rutile

This type of coating is designated by the letter “P”. Rods coated with a rutile compound show good results even when working with metals that have rusty areas or traces of scale on the surface at the welding sites; hot cracks do not form during the process of joining parts.

Do not use electrodes with chipped coating

Using electrodes with rutile coating, it is easy to connect primed elements, while the characteristics of the seam do not deteriorate. Rutile coating promotes stable arc burning regardless of the type of current. There are virtually no splashes of hot metal. Rutile rods are also characterized by a low percentage of defects in the form of pores: when used, the likelihood of “starting porosity” is negated.

When welding with electrodes of medium and large thickness, work in all permissible positions is possible. If the thickness of the coating on which welding is performed is particularly thick, then it is most effective to weld in the lower position. Electrodes with rutile coating should not be used for welding elements that will be operated at high temperatures.

Here is more information about rutile electrodes.

Source: https://WeldElec.com/pokrytie-elektrodov/

Classification of electrodes by type of coating

Do you need to carry out welding work in production manually or semi-automatically? Do you want to buy materials for your personal welding machine?

Understanding the variety of welding materials is not an easy task: which one to choose, what to pay special attention to? Technical literature gives standardized designations. To compare electrodes and choose the right one, consider their types.

Let us immediately make a reservation that uncoated metal electrodes were used in the early stages of the development of welding technologies. Later they were transformed into a continuous metal wire, welding with it is carried out in a protective gas environment.

For welding steels and their alloys, the most common are metal consumable electrodes with a coating, which is applied by dipping or coating and is a combination of components that provides certain properties to the weld. They are classified according to the type of coating by GOST 9466-75.

Types of electrode coating

The designation of electrodes according to state standards determines their main characteristics. Depending on the welding characteristics and types of coating, they can be divided into:

Type of coating Characteristics GOST 9466‐75/ISO (international designation) Electrode grades (example) Note

Basic	The seam is high quality; the arc is short; Welding current is constant, reverse polarity; weld pool protection is good.	B/B	UONI 13/45 UONI 13/55SM-11	Used for welding vessels/pipelines operating under excess pressure (Rostechnadzor control)
Rutile	Arc burning is stable; DC/AC current; high-quality seam; satisfactory protection of the weld pool.	Р/R	MR-3 OZS-12OZS-4	Structures under the authority of Rostechnadzor
Sour	The arc is unstable; high toxicity of the process; tendency to pore formation; metal splashing; direct/alternating current.	A/A	TsM-7 SM-5OMM-5	Steels with low carbon content, small thicknesses
Pulp	DC/AC current in all spatial positions of the seam; welding without overheating; Spattering (large losses).	C/S	CC-1 VSC-4AOMA-2	Recommended for field welding

The ratio of the diameter of the electrode to the diameter of its rod determines the thickness of the coating. There are products with thin (M), medium (C), thick (D), and extra thick (G) coatings. The last three groups provide the best seam quality.

The diameter of the electrodes varies from 1.6 to 12 mm. Moreover, 6 - 12 mm are used for surfacing, less than 6 mm - for welding.

Let's take a closer look at the types of coatings.

Basic coating

The main type of coating has a slag base containing Ca and Mg carbonates and fluorspar. This coating composition ensures a low presence of hydrogen in the weld. This is an indispensable quality for welding high-carbon steels subjected to improvement and hardening. In other cases, hydrogen released during the welding process penetrates into the heat-affected space and can cause cracks.

The electrodes have a core made of low carbon wire Sv-08 (or Sv-08A). In terms of its physical properties, this welding material corresponds to type E42A - E50A (classification that determines the characteristics of the seam: 42 - 50 kgf/mm² - min. temporary tensile strength). Welding can be carried out at any location of the seam.

Suitable for high-carbon and alloy steels. It performs satisfactorily with significant seam sizes. If there is scale, rust, or moisture on the metal surface, then there is a high probability of pores forming at the welding site. Arc stability is less than with all other types of coating (direct current, reverse polarity).

Before welding, it is recommended to calcinate the electrodes (t=345 – 405°C).

Rutile coating

The basis of these welding materials is Sv-08 wire; the coating of rutile electrodes contains mainly titanium oxide. It provides high arc stability and is used for vertical and ceiling joints.

The fact of high-quality welding on primed surfaces up to 25 microns thick has been recorded. When welding with rutile electrodes, the toxicity is low, and there is no large spattering of metal.

The joints welded by them have increased strength fatigue. Electrodes correspond to grades E42 - E46. Rutile electrodes are resistant to the formation of cracks and pores in the weld metal, however, they are not suitable for making T-welds at increased gap values. They are not recommended for welding thin metal and increasing the welding current values.

If the electrodes are damp, they must be dried at t=200°C; the welding process can only be carried out the next day.

Acid coating

The base is low carbon wire Sv-08. Chemical elements included in the coating are manganese ore, silica, iron oxides.

The advantages include the absence of pores when carrying out the welding process against rust and scale, the arc is stable, easy ignition at 60 - 70 V on the transformer, significant productivity at any position of the seam in space.

Disadvantages: metal spattering, toxicity, tendency to cause pores and cracks. Acid coating of electrodes is applicable only for welding low-carbon unalloyed steels and corresponds to grades E38 - E42.

Cellulose coating

The basis of such coatings is organic substances, which, when burned, release protective gases for the weld pool. Such electrodes do not contribute to the formation of pores, produce a stable arc, and allow welding in any position of the seam.

The disadvantages include: increased hydrogen content in the weld zone, which contributes to the occurrence of hot and cold cracks in the metal being welded; significant splashing.

The scope of application of this welding material is the installation of main pipelines. Root weld penetration. Brands of electrodes are regulated by in-plant standards or technical specifications.

Source: https://ngsgroup.ru/blog/welding-materials/classification-type-coating-electrode/

Classification of coated steel electrodes

In welding, an electrode means a metal or non-metallic rod made of electrically conductive materials that supplies current to the metal being welded. Without this product, welding work is impossible. Modern classification of electrodes helps you figure out where to use which. Today, there are different types of electrodes for welding, depending on the characteristics of their parameters.

Electrode welding process

Electrodes for welding

Products intended for welding are made of materials that conduct electric current. Thanks to its supply to the welding site, the melting of materials is ensured with the subsequent formation of a welding seam. The product consists of wire, which is its base, and a special coating.

The coating is an important part of the product and provides a number of functions that are necessary for the welding process. The length of the rods varies from two hundred and fifty to seven hundred millimeters. They are mounted in a special holder, so the last twenty to thirty millimeters of the rod are not coated.

Regardless of what kind of welding electrodes there are, they all must provide:

• stable arc burning with uniform melting of metal and its transfer to the weld pool;
• protection of metal from oxygen;
• formation of a seam with optimal chemical characteristics and mechanical properties;
• high welding performance;
• minimal losses associated with splashing and waste;
• minimal toxicity of gases released during the welding process.

Similar properties are provided by the coating of the rods. Their composition plays an important role in this. You can learn about the properties of a particular rod, its chemical, physical and other characteristics by looking at the markings.

Features of product labeling

The rods differ in their purpose, diameter, and type. Classification of electrodes involves dividing them according to certain properties and designating specific types using letters and numbers. Each type has its own marking, with which you can learn about its characteristics.

"Important!

The labeling indicates the type of product, its dimensions, brand, coating features and other important parameters.”

As an example for a clear decoding, we can take the following marking “E46-ANO-21-2,5-U DE 43 0/3/ -P-11” under which the “ANO-21” rods are distributed. It is deciphered as follows:

• “E46” - product type;
• “ANO-21” is his brand;
• “2.5” is an indicator of the diameter of the rod (in this case 2.5 millimeters);
• “U” - purpose of the product (rods with the index “U” are used for processing low-alloy or carbon steel);
• “D” is a coefficient indicating the thickness of the wire coating. In this case there is a thick coating. Other options: M – thin; C – average; G – extra thick;
• “E” - this index is the international designation of the coating of the rod (consumable);
• “43” - designation of ultimate strength (430 MPa);
• “0” – relative elongation (less than twenty percent);
• “3” - the index indicates the temperature under which the impact strength of the metal does not exceed thirty-four J/cm2 (-20 degrees Celsius);
• “P” - type of coating (rutile);
• “1”—possible spatial positions (all are acceptable);
• “1” is the permissible welding current and the open-circuit voltage indicator (in this case, it is possible to work with direct/alternating current, the open-circuit voltage parameter is about fifty watts).

Source: https://steelfactoryrus.com/klassifikatsiya-stalnyh-pokrytyh-elektrodov/

Selection of electrodes for welding: inverter, for manual welding, taking into account the material, marking of electrodes

One of the main conditions for obtaining a high-quality and correct welding seam is high-quality, correctly selected electrodes for welding with an inverter machine.
The modern market has a very large assortment for electric welding. They all differ in type, coating material and other characteristics. Below we invite you to familiarize yourself with the available options and choose the most suitable one.

All existing electrodes for electric welding are divided into consumable and non-consumable. The consumable electrode is based on a wire rod made of metal wire, coated on the outside with a special coating. Thanks to the coating, the welding arc can burn stably, and the coating also provides good protection of the seam from gas and slag.

Electrodes, the purpose of which is to weld steel of unknown composition, as well as copper, stainless steel, cast iron and other metals, are made from a specific alloy. Non-consumable types of electrodes are most often used when working with argon welding.

Working welding elements are available in different lengths and diameters.
The length of the electrode depends on the alloying characteristics of the steel wire rod of the product, and can range from 30 to 45 centimeters. Regardless of the diameter, all types of electrodes find the widest application. The only exception is the diameter of 1.6 mm. This type of electrodes is available upon request only. They are practically not used by Russian welders.

The most commonly used classification of all existing electrodes is according to their purpose. Based on this parameter, electrodes are divided into:

• Designed for working with elements made of carbon and low-alloy steels. • For working with high-strength heat-resistant steels. • “Electrodes for stainless steel” - for working with high-alloy steel. • “Electrodes for aluminum”.

• Electrodes for welding copper parts and products based on it. • Electrodes for cast iron. • For repairs and surfacing. • For welding work on metals whose composition is not determined.

Classification according to the type of electrode coating is also quite often used.

There are four main types of coatings, but only two are widely used.

Basic type electrodes.

They got their name because the electrode rod has a so-called base coating. The most popular among the main electrodes is the UONI 13/55 model. The use of this product allows you to obtain high-quality seams with high impact resistance, strength and ductility. In addition, crystalline cracks rarely appear on such seams, and they are poorly prone to “aging.”

UONI electrodes are typically used for high-responsibility welding work and products that will operate in harsh conditions. The disadvantages of this type of electrode include arc elongation, instability of the coating to moisture and rust, and the appearance of scale or oil in the weld area. Taken together, all this can lead to the appearance of micropores.

In addition, the main electrodes can only operate on reverse direct current.

The second type of electrodes has a rutile coating.

These products are used when welding parts made of metal with a low carbon content. The most commonly used grade is MP-3. These electrodes have good technological qualities, namely:

• The electric arc burns stably on both direct and alternating current. • The red-hot metal practically does not spatter.

• High quality seams in any position of the parts being welded.

• Slag is separated very well. • Electrodes can be used for working on dirty and rusty surfaces. • Finished welds have a very good appearance, without pores or cavities.

• Well suited for welding steel parts with low carbon content.

The correct choice of electrode for work, of course, plays a big role, however, in addition to this, you still need to know what polarity and current you need to work with in each specific case. Almost all inverters use direct current. When working with direct current, the electrode part can be connected in several ways, namely:

If the polarity is straight, the electrode is connected to “minus” and the part to “plus”.

When working with reverse polarity, on the contrary, the electrode is connected to “plus” and the workpiece to “minus”.

During operation with direct polarity, a higher temperature is generated when compared with the same values ​​when operating with reverse polarity. Therefore, working with reverse polarity makes sense in the following cases:

• If it is necessary to weld thin sheet metal. Since the temperature at reverse polarity is lower, the workpiece will not burn.

• When working with high-alloy steel grades. “Return” in this case significantly reduces the likelihood of the part overheating.

It is better to work with direct polarity with massive workpieces that need to be well heated for high-quality welding.

In welding, there are three main characteristics on which the quality of work directly depends:

• Welding current. • Diameter of the workpiece.

• Thickness of working material.

First, you need to decide on the relationship between the diameter of the working element and the thickness of the part to be worked with. For example, steel up to 1.5 mm thick. It is almost always cooked using a semi-automatic machine or argon welding.

Electric arc welding is practically not used for this. Steel 2mm thick is welded with electrodes with a diameter of 2.5mm. To qualitatively weld steel 3 mm thick, you will need electrodes with a diameter of 2.5-3 mm.

For steel with a thickness of 5 mm - an electrode of 3.2-4 mm. When working with products with a thickness of 6 to 12 mm. working elements with a diameter of 4-5 mm are used.

For steel thicker than 13 mm. use a 5 mm electrode.

An important point: the larger the electrode diameter, the lower the operating current density. As a result, the arc begins to oscillate, “wander,” change length and behave unstable. Because of this, the depth of the seam decreases, and the width, on the contrary, increases. In most cases, manufacturers of such electrodes indicate the required welding current indicators on the packaging. If the manufacturer has not provided the necessary information, you need to focus on the following indicators:

• For an electrode with a diameter of 2 mm, a current of 55-65 A is required. • For an electrode with a width of 2.5 mm - 65-80 A. • For 3 mm - 70-130 A. • For 4 mm - 130-160 A. • For 5 mm - 180 -210 A.

• For 6 mm – 210-240 A.

Based on the above, when choosing a working element of a certain diameter for welding work, you must first of all pay attention to the thickness of the workpiece. If you work on thin metal with a large-diameter electrode, or exceed the welding current, then pores will certainly remain in the weld.

Marking of welding electrodes

The most common brand among foreign electrode manufacturers is ESAB.

The name of each type of electrode of this brand begins with OK, followed by a 4-digit designation. There are many variations on sale, but the most common are the following:

• OK 46.00 – the electrode is almost similar to the properties of the MP-3 brand. Excellent for low alloy and carbon steels. Suitable for AC and DC. Provides high quality seam.

• OK 48.00. Designed for use on critical structures. They operate on direct current only.

• OK 61.30 and OK 63.20. They are used when welding stainless steel of almost all brands. Before purchasing, be sure to ask your sales consultant whether these electrodes are suitable for working with a specific grade of stainless steel.

• OK 68.81. Great model. Excellent for welding steel products of indefinite composition and difficult-to-weld parts.

• OK 92.60. Electrodes for cast iron and connections of cast iron parts with different types of steel.

• OK 96.20. Electrodes for aluminum.

Criteria for selecting suitable electrodes

Having analyzed all of the above, we can identify several main points that you must pay attention to when choosing electrodes for electric welding. First, you need to determine exactly what metal you will be working with and select an electrode based on the type of metal. If you have to work with a critical design, it is better not to save money and buy products from a well-known manufacturer.

For example, the Swedish products that we mentioned above have proven themselves very well. If you need to weld carbon steel parts, be sure to keep the surface clean. If it is coated with oil, damp or rusty, you should purchase electrodes that have a rutile coating. If you have to work on critical structures, it is recommended to use working elements with a basic coating.

However, in any situation, you need to remember that all products require preliminary surface preparation.
In addition, it is necessary to accurately determine the thickness of the workpiece, based on which to select the optimal welding current. The selection process must be approached as responsibly as possible. If the electrodes are chosen correctly, then even the cheapest inverter can cook almost any metal at the highest level.

Source: http://svouimirukami.ru/companies/elektrody-dlya-svarki-markirovka-elektrodov-kakie-elektrody-vybrat.html

Electrodes for alternating current: marking, how to distinguish, what current strength and which electrodes are better

There are a great variety of welding machines. They vary in functions, dimensions and many other criteria. But one of the most important technical indicators is the type of welding current obtained at the output during the welding process. There are only two such types: constant and variable.

Correct AC welding electrodes are the key to quality welder work. They have their own characteristics and precise technical characteristics.

What is alternating current in welding

Is it good or bad, which current is better? Variable or constant? No one will give you a definite answer.

To begin with, it is better to understand the features of processes with alternating current, they are as follows:

• The behavior of the arc leaves much to be desired: with alternating voltage it is the most unstable.
• The welding seam is not of the highest quality due to deviation from the axis of the welding arc.
• If the arc goes out, its combustion can only be resumed when the voltage increases.
• The metal is splattered to a large extent.

Despite all these complexities, the equipment required for AC welding is simple and inexpensive. These are, first of all, transformers - devices that are still very popular among welding masters.

It would seem that electrodes for alternating current should gradually lose their relevance: after all, many rectifiers have appeared on the market - inexpensive and with small dimensions convenient for use. However, these consumables are still in demand in many industries and handicraft workshops.

Most of the brands are universal, which is also extremely suitable for older generation domestic welders.

If you look at it, the best consumables for “change” have and show very serious production advantages. First of all, this concerns the resulting electric arc: its durability and easy ignition. Another feature of such electrodes is the low level of metal spattering during welding.

Welding transformer

Electrode diameter and steel thickness.

To carry out welding using a transformer, the following mandatory structural elements are required:

• Windings primary and secondary. The primary is made of a special insulated wire; there is no insulation on the secondary winding.
• Magnetic wire.
• Screw for controlling the position of two windings and changing the distance between them.
• Protective housing for the entire unit.
• Screw handle, running nut.
• Fan and other elements depending on the transformer model.

Despite the fact that many welding professionals regard transformers as equipment of the “outgoing generation,” they are presented on the market in the form of a wide range of models of very different values ​​and for wallets of any thickness.

Transformers differ according to the following criteria:

• dimensions and weight;
• output current strength;
• output voltage level at idle;
• volume of electricity consumed;

Welding generator

The generator design includes the required structural elements:

• The most important part - the converter consists of an electric generating element with an alternating voltage motor. They provide changes in current indicators.
• Drive internal combustion engine.
• Indicator for monitoring and recording current strength.
• Mode switches.
• Special circuit breaker.
• Regulators for current and arc behavior.
• Terminals for connecting cables and 230V outlets.

These types of generators are available in two versions:

1. Collector generators.
2. Valve generators.

The main advantages of a gas generator in comparison with other welding machines are:

• Compact and therefore highly mobile.
• Convenience, relative cheapness, noiselessness.
• Wide functionality and high reliability.
• Quite high technical characteristics.

AC electrodes

Electrodes for alternating current have an interesting feature: they are universal, that is, they are suitable for working with both alternating and direct voltage. Let us immediately note that electrodes for direct current do not in any way possess such versatility.

AC electrodes are used where transformers and generators are used as welding machines. Like the devices themselves, these electrodes are in great demand, since these methods can only be used during recess.

Both units and consumables are significantly cheaper than welding technologies based on the use of constant voltage. So the popularity and demand for “change” is not going to decrease.

Electrode markings for different types of coatings.

Advantages of AC electrodes:

• The use of alternating consumables does not require rectifiers in addition to the transformer.
• The weld pool is not exposed to the harmful effects of nitrogen and oxygen from the air.
• The versatility of this type of consumables.

Disadvantages of variable consumables:

• The main disadvantage is that the quality of the welds is lower than when using constant voltage.
• Spattering of metal during welding.
• Low viscosity is under attack.

Four types of electrode coating:

1. An acidic coating with the marking letter A, containing a high proportion of oxygen. This is a typical “station wagon”; such consumables can also be used on direct current.
2. “Basic” coating marked with the letter B. They have a high ionization potential, which is why it is better not to work with them on alternating current.
3. Rutile coating usually consists of half a special rutile concentrate, and it is very loyal to alternating current.
4. Cellulose electrodes are suitable for direct current operation.

AC electrodes

Types of electrodes for welding with alternating and direct current.

The type of current is indicated in all markings of consumables - this is always the last digit. The main thing is to remember that if the last place in the marking is 0, then the electrode is not suitable for welding with alternating current.

• OZS – 12 with rutile coating. The most common type of electrodes for welding with alternating current, which is used on almost all Russian-made machines. Excellent welding of carbon steel parts, suitable for connections of critical structures. Significant advantages of these electrodes are the ability to work in any position in space, the absence of pores in the seam, a stable arc, and a completely acceptable dose of toxic gases released during the welding process.
• MP – 3 are designed for welding low-carbon steels. The advantages are similar: excellent arc stability, acceptable metal spatter. The slag crust comes off very easily. With these consumables you can cook even rusty, damp and poorly cleaned workpieces.
• ANO – 4 are also used for carbon steels. Excellent arc that ignites quickly and easily. You can cook wet and rusty products. There are no pores or cracks during seam formation. Easy separation of slag crust. There is virtually no metal spattering.
• MP-3C are distinguished by their high versatility: they are suitable for both low-alloy and carbon steels. The arc is ignited easily and instantly, the seam is protected from slag and oxides due to the rutile coating. The seams are smooth and durable, they can withstand significant loads. You can work with them in any position in space.
• ANO – 6 are used for connecting parts made of low-carbon steels. They are not afraid of rust, scale and dirt. The arc is stable and easily ignited, the seam is formed correctly.
• OZS – 4 for carbon steels, can be welded in any spatial position. The arc ignites easily. You can weld metal workpieces with edges of medium and large thickness at high temperatures. Attention! Doesn't like dirt on the surfaces being welded - they stop working.
• ANO – 21 are also intended for steels with carbon additives and low-alloy alloys. They are very easy to handle, can be worked in any position, and are also used in conjunction with an inverter and a semi-automatic transformer. The metal hardly splashes during operation, and the slag in the form of a crust is easily separated. An arc with excellent qualities - stable and soft.
• OZS – 6 are intended for carbon steels. They are characterized by a high throughput speed, which gives high labor productivity with a welding seam of excellent quality. Capable of welding oxidized surfaces.

electrodes for direct current

Differences in welding with different current polarities.

Types of electrodes used for DC welding:

• UONI - 13/55 - famous electrodes of their kind for direct current, applicable for steel alloys - with low doses of alloying elements and with the addition of carbon. They have significant advantages: the welding seam is very plastic and tough for mechanical stress, very durable. Almost no impurities and gases are formed. The arc is easily ignited. A wire of parameters Sv-08 or Sv-08A is placed in the rod.
• UONI - 13/45 are also used for joining workpieces made of carbon and low-alloy steels. The seam is not inclined to form cracks - neither hot nor cold. It is very ductile and tough, with ideal tightness, which makes it a suitable option for welding containers that will subsequently be subject to high pressure. Seams made with these electrodes do not age much longer.
• OZL – 6 are distinguished by their narrow focus: they are used in working with heat-resistant steels. Pores and cracks do not form in the seams, they are not subject to further corrosion and have the same heat resistance as the base metal. Suitable for metals with different structures.
• OZS-12 are intended for steel alloys with a low proportion of alloying additives and carbon. It is possible to work in any spatial position and is tolerant of surfaces with rust. The weld is formed with excellent characteristics: strength and durability. Stable arc. There are no releases of toxic substances during operation.
• TsL - 11 are also highly specialized electrodes, which are intended for steel alloys with additions of chromium and nickel, as well as corrosion-resistant steels. Welded seams are resistant to corrosion. The metal hardly spatters, the arc is stable, and the slag in the form of a crust is easily separated.
• ANO - 21, despite the fact that they are also intended for carbon and low-alloy steel alloys, like previous brands of electrodes, these consumables are extremely popular among craftsmen of various levels of professional training. Their features are a fine-scale structure of the weld metal, excellent arc ignition, softness, slight metal spattering, and so on.
• LB – 52U are distinguished by the high productivity of the welding process with their help. The arc is stable, the metal hardly spatters, work is possible in any position in space, and almost no cracks form in the seam.
• MR - 3 typical universal electrodes, which are rightfully present in both lists - for both alternating and direct current. Pores and hot cracks practically do not form in the weld, the arc is powerful and stable, there is little spattering of metal, and easy separation of slag in the form of a crust.
• OZCH – 2 are intended for welding cast iron. Despite their seemingly narrow functional focus, they have solid advantages in the form of versatility, ease of use, an excellent arc with excellent characteristics, ductility of the weld without cracks, and a well-separated crust with slag at the end of the process.

Electrodes for alternating current Link to main publication

Source: https://tutsvarka.ru/vidy/elektrody-dlya-peremennogo-toka

What types of electrodes are there for welding - Metalworker's Handbook

To get a good result in the form of a high-quality weld, before starting welding work, you must carefully study the materials required for production. You need to understand the types of electrodes, because universal products for welding do not yet exist. Each type is used for a specific material and under certain conditions.

Classification of welding electrodes

Electrodes are the most popular consumables for welding or cutting metal products. A welding electrode is a conductive rod through which electric current from the welding machine is transmitted to the place where the metal is melted.

Non-consumable graphite electrode

An electrode is a rod of a certain size made of metal or other material. There are various types of electrodes for welding:

• Non-consumable rods are made of graphite, and can also be thoriated, itrated and carbon.
• Consumable electrodes are made from alloyed, high-alloyed and carbon grades of steel, bronze, copper, cast iron and other metals. These products have a coating that performs several functions when melting metal. His “responsibilities” include protection from the gas phase of the weld pool and stabilization of the electric arc.

Alkaline-coated products easily form and stabilize an arc.

The welding process occurs as follows. The edges of the metal parts are melted by the heat produced by the electric arc - the flow of ions between the anode and cathode. A short circuit that occurs between two poles causes the ionization process.

Welding is performed with one electrode or several, between which an additional arc is created. This method is called three-phase arc welding.

How to choose a welding electrode by marking

Various types of electrodes are used in industry to join metals that have different melting points. For each task, a special type of welding electrode is selected. For example, one brand of welding electrodes is used for thin sheet steel 0.5 mm thick, another type connects metal profiles 5 mm thick.

There are many types of rods that are difficult to classify. Types for steel welding are determined according to GOST 9467-75. For example, in the alphanumeric designations of brands E42A, E38 and E50A:

• "E" stands for "electrode"
• the number indicates the minimum tensile strength time,
• the letter “A” determines the possibility of using weldable ductile metal of high viscosity.
• the letter “H” denotes products for fusing onto different surfaces,
• the letter “U” marks rods for connecting products made of carbon steel,
• the letter “T” is for products made of alloyed heat-resistant steels.

The chemical elements that make up the surfacing are also reflected in the marking of the electrode, for example:

• "X" - chrome,
• "M" - molybdenum,
• “B” – niobium,
• “F” is vanadium.

A large number of brands of welding electrodes belong to one class of domestic and foreign welding materials.

Wire for the production of electrodes is marked as follows:

• the letters St mean welding type,
• the number after the letters determines the percentage of carbon in the metal,
• the letter code indicates the presence of alloying substances,
• the next number indicates the percentage of these elements in the rod.

The composition of the wire and steel parts must be selected in accordance with each other.

Electrodes with different coating compositions are used for different materials, selecting a specific type for each case. Electrode coatings are marked:

• B – basic . They contain calcium fluoride and carbonate, which reacts with oxygen when the arc burns and produces carbon dioxide as a protection. Welding is performed using direct current of reverse polarity. Using alternating current produces a poor quality seam and requires additional measures to improve its quality.
• A - sour . The composition contains ferrosilicon and ferromanganese. Such rods are used to create bottom seams with direct current and melt metals at high speed.
• R – rutile . Contains liquid glass, titanium dioxide (rutile), ferromanganese, carbonate and aluminosilicates. Rutile electrodes are used for DC welding of connections in any location. The slag formed as a result of a chemical reaction protects the elements from burning out. The compounds are of high quality and non-toxic.
• C – cellulose . Such products contain cellulose, manganese, ferromanganese, talc and rutile. They are used to produce any good quality seams at high speed. Shielding gases are formed around the weld pool and arc. During operation, you need to ensure that the connection overheats. The material splashes during operation, so the method is considered uneconomical. It is used for the production of pipeline connections for various purposes.
• P – other . Rods containing alloying elements are used to improve the quality of the connection.
• S – special . They are used for underwater welding work, as they create a seam protected from moisture penetration. The composition contains liquid glass mixed with substances containing resins.

All electrodes with a certain type of coating are intended for specific cases. Rutile coating is considered universal and is the main type. The protective function of the coating is performed by oxidizing the alloy, adding alloying substances and creating a protective halo of slag or gases. In this way, solid welds of good quality are formed.

However, when choosing the type of electrode, you need to focus not on its markings, but on the characteristics of the product, which are determined by technical standards.

Basic criteria for selecting welding electrodes

Products for welding work primarily pay attention to its diameter, its appearance - melting or non-melting, the polarity and type of electric current, the type of coating and the location of the seam.

When choosing welding electrodes, it is necessary to take into account the shape of the edge of the metal sheet, its brand and electric current parameters. Such an important parameter of products as diameter is determined by the thickness of the materials being joined.

The thinnest rods with a diameter of 0.1 cm are used when welding with a current of 20 to 25 A metal sheets up to 0.015 cm thick. Products with a thickness of 0.3-0.4 cm are the most common and are used for welding metals less than 0.10 cm thick.

In this case, a current of no more than 220 A is used.

The larger the diameter, the more powerful the welding equipment used. The maximum diameter of the products is 1.2 cm. For everyday tasks, 3 mm electrodes are used. If the rod size is less than 2 mm, the electrode is used to connect thin sheets of metal.

In industry, the “four” is more often used, and electrodes thicker than 5 mm are used in construction, shipbuilding and bridge building, and in other large industries.

Stainless steel and aluminum are joined using tungsten electrodes, using alternating current to produce a better quality weld. Carbon steel products are connected by rutile-coated electrodes.

Source: https://ssk2121.com/kakie-byvayut-elektrody-dlya-svarki/