What types of welding are classified as fusion welding

Classification of types of metal welding

In fusion welding, the metal in the weld zone is heated until it melts. The liquid metal of the parts being connected merges into a common “weld pool”, which upon solidification turns into a strong “weld seam”.

Main types of metal fusion welding

• Gas welding,
• Gas-electric welding,
• Electric arc welding,
• Thermite welding,
• Electroslag welding.

Welding of dissimilar metals is also possible.

Fusion fusion does not require particularly thorough cleaning of the surfaces being joined; contaminants are removed from the metal, floating to the surface of the weld pool.

The disadvantages of fusion welding include possible overheating of the metal and a sharp local change in its structure and composition.

When pressure welding metals with heating, the metal is brought to “welding heat,” i.e., a temperature range within which it remains solid, but is already welded well as a result of the application of pressure. (Gas press welding, Contact electric welding, Forge welding).

When welding with pressure without heating (cold), the parts being connected are compressed, simultaneously forcing the metal to flow along the interface, which is necessary for some cleansing of oxides and bringing the metals closer together in order to enhance atomic interaction. In this way, parts made of aluminum, lead, tin, copper, silver and other non-ferrous metals and alloys are welded in not very critical joints.

Another type is friction welding.

Gas welding

Acetylene is usually used as fuel. For welding cast iron and non-ferrous metals, methane, propane-butane mixture, oil gas, etc. can be used.

Gas welding is often performed by introducing a filler rod into the molten base metal.

Depending on the location of the burner flame and filler rod in relation to the weld, “left” and “right” welding are distinguished.

• In “left-handed” welding, the torch and filler rod move from right to left; the welded seam remains behind the burner.
• In “right” welding, the torch and filler metal move from left to right, the flame is directed towards the already welded part of the seam.

With “right” welding, the quality of the welded joint and labor productivity are higher, however, due to the danger of burnout, it is usually applied only to metal with a thickness of more than 3-5 mm.

Gas welding is used for permanent connection of thin-walled steel parts, products made of cast iron, non-ferrous metals and alloys, as well as for surfacing hard alloys.

Gas-electric welding

Depending on the protective environment and implementation techniques, a number of varieties are distinguished. In gas-electric welding with a consumable electrode, the arc is located between the product being welded and the electrode supplied to the welding zone, which, melting, drops into the seam (Fig. a).

Scheme of gas-electric welding: a - consumable electrode; b - non-consumable electrode; 1 - current supply mouthpiece; 2 - gas nozzle; 3 — jet of protective gas; 4 - welding arc; 5 - weld pool; c - seam; 7 - metal to be welded; 8—added metal.

When gas-electric welding with a non-consumable tungsten or carbon electrode (Fig., b), the seam is formed as a result of melting the metal of the welded products; in some cases, filler metal in the form of a rod is additionally introduced into the electric arc.

Argon arc welding (in the protective environment of argon) has become most widespread due to the versatility of its application and the high quality of welding of various metals and alloys. For argon-arc welding with a consumable electrode, mixtures of argon and oxygen (1-5%) are also used, which provides a finer-droplet transfer of the electrode metal.

In order to reduce the consumption of scarce argon, combined gas protection of the welding zone is sometimes used: argon in the center, and other protective gases, such as carbon dioxide, along the periphery. To join parts made of carbon and stainless steels, welding in an environment of cheap carbon dioxide is increasingly used.

To increase productivity and quality, gas-slag protection is also used, for example, using a special wire as a filler metal, or flux is introduced into the welding zone.

In atomic hydrogen welding, a stream of hydrogen H2 is fed into the arc between tungsten electrodes, which is partially dissociated, turning into atomic hydrogen H2. Hydrogen effectively protects the metal from oxidation during the welding process. In contact with the relatively cold surface of the metal being welded, atomic hydrogen again transforms into molecular hydrogen, releasing heat previously spent on dissociation.

Moreover, hydrogen burns, which provides additional heat. As a result, a high temperature develops at the surface of the metal being welded (about 3700 °), due to which welding occurs. Atomic hydrogen is used in the manufacture of particularly critical thin-walled structures from high-carbon and alloy steels, as well as from aluminum alloys (in the latter case, special fluxes are used).

Gas press welding

Acetylene is usually used as fuel. Mostly parts made of steel, brass, copper, and aluminum alloys are welded. Gas press welding is used both in workshop and in construction, installation and field conditions.

Forge welding

Low-carbon steel (up to 0.25-0.3% C) is welded well; steel with 0.45% C or more is almost impossible to forge weld and can only be welded onto mild steel.

To dissolve scale and liquefy welding slags formed during heating of steel and preventing the connection of non-oxidized metal at the welding site, it is usually sprinkled with flux (sand) before compression; during compression, all these liquid non-metallic components are squeezed out of the seam.

Thermite welding

There are two types of thermite welding: pressure and fusion.

When pressure welding, only the heat of slag and thermite metal is used to heat the parts being joined. An example of a successful application of pressure is the welding of iron communication wires on a line using magnesium thermite, the duration of such welding is several seconds.

In fusion welding, the thermite metal between the surfaces being joined together with the molten metal of the parts forms a cast seam. To alloy the thermite metal with Mn, Si, Cr, Mo and other elements, oxides of these metals or ferroalloys are introduced into the thermite. This way you can obtain steel of various compositions and properties, for example when welding rails. The fusion welded ends are enclosed in a fireproof mold. Thermite welding in some cases is successfully replaced by electroslag welding.

Contact electric welding

Electric current is supplied to the parts through electrodes made of copper or copper alloys.

Based on the type of welded joints, there are three main types of contact electric welding:

• point,
• suture
• butt.

With electric spot welding (Fig. 1), the connection between parts is carried out over a relatively small area (“point”).

Fig. 1 Spot welding diagram.

The strongest joints are obtained by melting metal in contact between parts, forming a cast core in the shape of a lentil. Spot resistance electric welding is used to connect parts with a thickness from hundredths of a millimeter to 4-5 mm, less often - thicker ones.

A type of spot welding is relief welding: due to the presence on one of the parts of several protrusions - reliefs (Fig. 2), welding occurs simultaneously at several points, the relief can take the form of a closed figure.

Fig. 2 Scheme of relief welding.

During seam resistance electric welding, a continuous row of points is formed, partially overlapping one another. The easiest way to obtain such a seam is on a machine with electrodes in the form of rotating rollers (Fig. 3).

Fig.2 Seam welding diagram.

In butt contact electric welding (Fig. 4), parts are joined that have identical cross sections at the junction.

Welding can be done using one of two methods.

1. The resistance method boils down to the fact that the parts are compressed and, moreover, heated by current.
2. When welding by fusion welding, parts to which voltage is applied slowly approach each other and local contacts arise between them, in the area of ​​which the metal quickly heats up to melting. Gradually, the ends of the parts are uniformly heated to a high temperature, after which the parts are compressed and the current is turned off.

Rice. 4. Butt welding diagram.

Contact electric welding is one of the most productive and easily automated welding methods.

It is widely used in many industries and construction, in particular in conditions of mechanization and automation of production.

Source: https://www.masterovoi.ru/vidy-svarki-metallov

What types of welding are there (description and advantages)

So, inverter welding - what is it? Essentially, inverter welding is a process that uses a circuit, system, or device whose job is to create an alternating voltage using a direct current source.

Inverter welding

The general circuit of such a welding machine includes a mains filter, mains rectifier, frequency converter, high-frequency transformer, power rectifier and control system.

Naturally, in order to weld metal structures, it is not enough just a welding machine; you will also need to use various accessories - a mask, holders and, of course, electrodes. Welding without electrodes is simply impossible. In the process of inverter welding, three types of electrodes are used - carbon, alloyed and high-alloyed.

The main advantages of welding work using an inverter machine are as follows:

• ignition is easy and quick, the arc burns steadily and has good elasticity;
• high quality weld;
• low energy costs during operation;
• fairly good efficiency;
• supply voltage fluctuations do not affect the quality parameters of welding joints;
• These devices are lightweight and mobile.

Naturally, like any process, inverter welding also has its disadvantages: inverter-type welding machines, like any complex electronic devices, are highly susceptible to the influence of water, dust and frost. For this reason, devices of this type must be stored in a room that provides the required parameters of dryness and warmth.

Another important point is the care of the welding machine; periodically it will be necessary to open the housing and blow through the components of the device with compressed air.

Argon welding

Argon welding is one of the types of welding work that allows welding complex and refractory metals. Using this welding method, aluminum and other metals that undergo an oxidation process when exposed to air are often welded.

Argon welding is most often used in industries such as the automotive industry, during the repair of various vehicle components made of aluminum. In addition, argon welding is used in the metallurgical industry, for example, to carry out hot processing of titanium, tantalum, niobium, beryllium, zirconium, hafnium, tungsten, uranium, thorium and to process alkali metals.

The use of argon as a gas is a fairly common practice; for example, light bulbs also contain it.

Argon welding is a rather complex process that requires high qualifications and modern equipment. However, the result of this process is at the same level - the seams are smooth, sometimes almost invisible, and at the same time very durable.

Argon-arc welding is carried out using tungsten electrodes and a ceramic nozzle. It is through this nozzle that argon is supplied to the welding site, which prevents the metal from coming into contact with the atmosphere. This, in turn, prevents oxidation of the metal and ensures a strong weld.

Argon welding can be divided into two types: manual welding and automatic

So what is good about argon arc cutting and welding of metal structures? To begin with, it is worth noting that due to the fact that this process uses modern equipment, the operating time is significantly reduced. In addition to this, the argon jet during welding work, in addition to protecting the metal from the influence of air, also blows away everything unnecessary and unnecessary.

Lastly, but most importantly, this type of welding work is very economical. This is due to the fact that with the help of argon, the electric arc is compressed and concentrated in a narrow area. For this reason, with relatively low energy costs, it is possible to reach a temperature of the cutting zone of the order of 40006000°C.

Argon arc welding

If you need to weld a steel structure, then, without thinking twice, you will pick up a welding machine and easily cope with this task. But what to do if welding work needs to be done, for example, for an aluminum structure? This is where argon arc welding can help you.

Argon arc welding is welding using an electric arc in an inert argon environment. Consumable or non-consumable electrodes can be used for this welding. A tungsten electrode is most often used as a non-consumable electrode.

The arc burns from the workpiece being welded to a non-consumable electrode (as already mentioned, most likely tungsten). The electrode is fastened to the burner, through the nozzle of which protective gas is supplied. The filler material is supplied to the arc zone from outside and is not included in the electrical circuit.

Argon welding can be performed in manual mode, when the welder controls the torch and filler rod, and in automatic mode, when the movement of the torch and filler wire is carried out without the help of a worker.

When welding with a non-consumable electrode, unlike welding with a consumable electrode, during ignition of the arc the electrode does not touch the product for such reasons. To begin with, argon has a high ionization potential, for this reason ionization of the arc gap using a spark from the electrode to the product is a rather difficult task.

In the case of argon welding using a consumable electrode, after the wire touches the part, the arc zone is saturated with metal vapors, which have an ionization potential almost three times lower than that of argon, as a result of which the arc is ignited.

In addition, if the part touches the tungsten electrode, things such as contamination and intense melting will occur. For this reason, during argon welding using a non-consumable electrode, a device called an “oscillator” is connected in parallel to the power supply network to ignite the arc.

Using an oscillator, to ignite the arc, high-frequency high-voltage pulses are supplied to the electrode, ionizing the arc space and ensuring ignition of the arc when the welding current is turned on. If argon welding is performed with alternating current, when the arc is ignited, the oscillator begins to work as a stabilizer, supplying pulses to the arc when the polarity changes.

This is necessary to prevent deionization of the arc space and ensure stable arc combustion.

During DC welding, the anode and cathode produce different heat. When currents are less than 300 A, the anode generates more heat than the cathode, 70 to 30 percentage, for this reason straight polarity is usually used to ensure maximum penetration of the part and minimal heating of the electrode.

When welding all steels, titanium and other materials except aluminum, straight polarity is used. When welding aluminum, alternating current is used to improve the destruction of the oxide film.

Argon is sometimes mixed with 3–5% oxygen to reduce porosity. This causes more active protection of the metal. Argon in its pure form protects the metal from phenomena such as moisture or other inclusions that enter the welding zone. And with the help of oxygen, harmful impurities are burned out, or released outside. And this helps fight porosity.

Semi-automatic welding machine without gas

If you decide to buy a semi-automatic welding machine without gas, then most likely you are already faced with a huge variety of different options on the market. Let's try to figure out what this device should look like in general.

The welding machine must be inexpensive and powerful. It is best for it to work semi-automatically, from direct current using a melting wire. It is desirable that in the machine, in addition to the mode of operation without gas on flux-cored wire, there is also the possibility of operating on gas (carbon dioxide and argon).

An important factor is the choice of the manufacturer. The manufacturer of the device you choose should be among the leaders in such areas as industrial and household production of equipment for welding work. This company must be officially represented on the market of your country, and have all quality and safety certificates, as well as have service centers.

The wire feed should be adjusted smoothly. It should be possible to implement stepwise power adjustment of welding currents from 50 to 140 A. Even a 5-kilogram spool of wire should be placed in the machine. The device must be equipped with thermal protection and forced air cooling. The machine must be able to operate with power from weak networks.

The winding in the device transformer must be made of copper. The device must be multifunctional; in addition to being used at home, the device must also cope with industrial needs (for example, a repair shop and service station). It would be good if the device is equipped with wheels for ease of transportation.

Well, lastly, and most importantly, when choosing a semi-automatic welding machine without gas, go to the Internet and carefully study the reviews of this device from people who have used it and who have something to compare with.

Source: http://postroyka-dom.com/kakie-vidy-svarki-byvayut-opisanie-i-preimushhestva/

Fusion welding and pressure welding: equipment, types and methods

Metal welding has long been used in industry, and the most popular is fusion welding using an electric arc. This manual method of joining metals was invented in the 80s of the last century, and over the past time new welding equipment and other types of electrodes have appeared. The process itself has changed: now for high-alloy alloys special electrodes are used and the weld area is protected with inert gases.

Nowadays, more than 20 types of electric welding are available to the welder, for example, in electrolyte, plasma jet, under argon protection. Even the classic method, in which an electric arc contacts metal through an electrode, has been modified to connect dielectric materials or metallize parts. This fusion welding technology is called indirect arc welding.

Technological process of indirect arc welding

During it, an arc occurs between two electrodes attached to a holder. Electricity does not go into the metal, and deposition occurs due to a closely located burning arc. You can regulate the level of metal deposition by moving the electric arc closer or further away.

Indirect welding is in demand for low-carbon steels, non-ferrous metals, and in the manufacture of small parts.

When it comes to smelting a small and very precise tool from metal, very slow heating is required in the melting zone. This effect can be achieved by atomic-hydrogen welding with indirect heating of the metal.

The principle is that hydrogen is supplied between two tungsten electrodes with a diameter of 1.5 to 4 mm when fusion welding of metals occurs. The gas entering the arc transforms from diatomic hydrogen into an atomic form.

This process requires the expenditure of energy, which hydrogen takes from the arc. Then touching the metal, the hydrogen turns into its normal form and releases energy. Thus, a weld pool is formed at the joint, in which the metals are joined.

Atomic-hydrogen welding is similar in quality to plasma welding.

The types and methods of fusion welding are so diverse that scientists have learned to use plasma to fuse and cut metals. The proposed method is based on blowing a jet of inert gas through two electrodes, creating a large arc discharge. Gas from the neutral channel enters the arc, as a result of which the gas molecules are ionized, creating a high-temperature plasma jet. The power of the jet is regulated by variations in gas composition or pressure changes.

The advantage of plasma is that it can cut stainless and aluminum alloys, which is impossible using the usual oxygen gas method.

Not only new welding methods appeared, but technology also developed. The industry demanded the rapid production of hundreds of template parts, and so automatic arc welding was born.

To solve the technological problem and increase productivity, automatic submerged arc welding was invented. The principle was that the welding wire was closed under a special substance - flux - which protected the welding site from exposure to the atmosphere and formed the welding seam. Fusion welding and pressure welding have their own characteristics.

And automatic welding allows:

• Increase work productivity through the use of high current and large diameter electrodes. The flux protects the welding area and also prevents metal from spattering. This allows you to save on material and create an even seam.
• Due to the fact that there are no losses from cinders and spattering, not only metal, but also electrically conductive wire is saved.
• The arc heat is used more efficiently, resulting in energy savings.

Semi-automatic welding

As a further development of the automatic method, semi-automatic welding was developed. In it, the arc is moved along the seam manually, and the wire is fed automatically. Electric fusion welding equipment has become popular in every enterprise. Especially where welding of hull structures containing a large number of corner joints is required.

Developments have appeared that allow welding even in the upper position. To keep the weld pool in place, it is held in place by a copper disk.

Electroslag welding

Gradually, automatic arc welding was transformed into electroslag welding. This method results in low power consumption, and thanks to the high current strength, it is possible to weld metals of large thickness.

The main advantage of electroslag welding is that there is no need to prepare the edges of the parts.

This welding is also divided into several types; the weld area is protected with flux or a gaseous environment. The most popular protection is made from argon, which does not allow the metal at the weld to oxidize. Later, more modern types of welding appeared, for example, vibrating arc surfacing. It allows you to apply a thin layer of metal to a part.

Source: https://steelguide.ru/svarka/vidy-svarki/svarka-metallov-plavleniem-texnologiya.html

What are the types of welding materials, their description and classification

When welding products, welding materials are used. They allow for stable arc burning and pore-free welds that are resistant to damage. Their classification and purpose will be presented below.

Welding materials perform the following functions:

• ensure stability of the welding process;
• remove harmful impurities from the weld metal;
• ensure the correct geometric dimensions of the seams;
• provide a weld material with a certain chemical composition and properties;
• help protect the molten metal from exposure to air.

Classification of welding materials

So , what categories are these materials divided into:

• electrodes and filler rods - these include electrodes with acidic, cellulose, mixed, rutile, basic and other coatings, as well as non-consumable electrodes;
• wire - can be activated, powdered or solid;
• fluxes - divided into electrically conductive and protective;
• gases - to support combustion, protective, which are active and inert, and flammable;
• ceramic pads - used to connect butt, fillet and T-joints; they can be all-position, round, etc.

Electrodes and wires

Wires and electrodes are needed to provide power to the welding zone for heating. Coated consumable electrodes, some types of wire and protective flux for arc welding include special components that can protect the metal from exposure to air, maintain process stability and help obtain a certain chemical composition of the weld metal and more. And the filler rod is introduced into the seam during welding.

Melting wires are used in the following situations:

• submerged;
• in protective gases;
• during electroslag welding.

There are three types of steel wires:

• alloyed;
• highly alloyed;
• low carbon.

In total there are 77 varieties in the assortment.

When choosing one brand or another, the chemical composition of the weld changes. Most often, wire is used whose composition resembles the metal that is being processed. The material must comply with GOST and be indicated on the product packaging.

In turn, low-carbon and alloy steel for wire production can be copper-plated or non-copper-plated. For manual welding, wire is used, which is cut into pieces 360-400 mm in length. You can buy it in skeins weighing 20−85 kg. Each skein has a label indicating the manufacturer and technical parameters of the product.

For work, you cannot use wire of questionable manufacture of an unknown brand. The surface of the filler wire must be smooth and free of grease, rust or scale. It must be selected according to its melting index; it must be lower than the similar characteristics of the materials being joined.

One of the quality properties of wire is its ability to melt gradually, without a sudden emission of splashes. If there is no special wire for connecting products made of stainless steel, brass, lead or copper, then use strips of cut metal from the same material that is being welded.

Plates and rods

The plates are used for electroslag welding, while arc welding is carried out using an electrode metal rod coated with an electrode base. There are three types of electrode thickness:

• thick;
• average;
• thin.

The type of welding material with different coatings is indicated by letters as follows:

• A - the coating has acid additives;
• B - classic version;
• C - the coating contains cellulose;
• P - mixed materials are present in the surface layer.

Gases

When cutting and gas welding, flammable gases and those that support combustion are used. These include:

• oxygen;
• acetylene;
• hydrogen;
• propane-butane mixture;
• methylacetylene allene fraction.

Shielding gases are designed to provide gas protection of the molten material from air. Shielding gases are:

• inert (helium, argon and mixtures based on them);
• active (carbon dioxide and mixtures based on it).

An inert gas cannot enter into a chemical reaction with a metal and is almost insoluble in it, but active gases are capable of entering into such a reaction and dissolving in metals.

As for oxygen , it is heavier than air and helps gases and vapors burn as quickly as possible, while heat can be released, and the melting point is maximum.

At the same time, compressed oxygen when interacting with lubricants and fatty oils can lead to an explosion and spontaneous ignition; accordingly, you should work with oxygen cylinders only in clean conditions, where this is excluded.

Oxygen-type welding materials must be stored only in compliance with fire safety standards.

Welding oxygen is technical, obtained from the atmosphere. And the air is processed in a separation apparatus, ultimately carbon dioxide impurities are removed, and the finished product is dried. In liquid form, oxygen for storage and transportation is contained in special containers with high thermal insulation.

Another gas, acetylene , is oxygen combined with hydrogen. At normal temperature, acetylene is in a gaseous state. It is colorless and contains impurities of hydrogen sulfide and ammonia. The danger is posed by the flammable components of such a material; welding pressure from 1.5 kgf/cm2 or accelerated heating to a temperature of 400 degrees can also lead to an explosion.

The gas is produced through an electric arc that separates liquid flammable components, or through the decomposition of calcium carbide under the influence of a liquid.

There are also substitutes for acetylene . According to the requirements for materials for welding work, it is possible to use liquid vapors and other materials. They are used if the heating temperature is twice the melting index of the metal.

In order for a particular type of gas to burn, a certain amount of oxygen is needed in the burner. Some flammable substances are used instead of acetylene because they are inexpensive and easy to obtain. They can be used in various industrial fields, but the use of such substances is limited due to their relatively low heating limit.

Welding fluxes and other materials

Flux has different purposes in the welding process. Thanks to it, it is possible to dissolve oxides on the metal surface, which facilitates the process of wetting the workpiece with molten metal. Flux also acts as a barrier to oxygen, acting as a coating on the hot surface of the workpiece, and prevents oxidation of the metal. The flux melt can also act as a heat exchange medium, facilitating heating of the joint.

Fluxes differ from each other in the following parameters:

• production method;
• purpose;
• its chemical composition and other parameters.

For example, depending on the production method, they are either fused or unfused. Fused fluxes are produced by fusing parts of a charge in furnaces. But the unfused parts of the flux charge can be held together without fusion.

Flux consists of a powder or paste of a certain composition; it is produced on the basis of boric acid or calcined borax. Fluxes are not used for joining alloy steels.

And another type of material for welding, a ceramic lining, is used to create a high-quality seam and form a reverse bead.

All of the listed welding materials can also be divided according to the type of metals and steels being welded. For example, some are intended for joining carbon steels, others for stainless or low-alloy steels or cast iron, copper and other materials.

General requirements for welding materials

Regardless of what type of welding is used, materials should be used in accordance with existing standards, which specify all the requirements for them. All factory products must have a certificate indicating the technical characteristics:

• manufacturer's trademark;
• alphanumeric symbols indicating the type and brand of the product;
• serial number of the shift and batch of heat;
• indicator of the surface condition of a wire or electrode;
• chemical composition of the material and the percentage of its components;
• mechanical features of a directional seam;
• net weight.

For all electrodes, an important requirement is a well-formed seam and an arc with stable combustion. The metal of the resulting guide must correspond to a predetermined chemical composition; during operation, the rod must uniformly melt, without splashing or releasing toxic components. The wire allows for high-quality work. Electrodes can retain their technical parameters for a very long time.

To produce quality work , it is important to take into account every detail. To ensure a strong and durable connection, use only high-quality materials and do everything according to the requirements.

Source: https://tokar.guru/svarka/svarochnye-materialy-klassifikaciya-i-harakteristiki.html

Welding classification

Fusion welding - (thermal class of welding) welding carried out by local fusion of joined parts without applying pressure. The classification of fusion welding is shown in Fig. 1.

Fig.1. Fusion welding classification

Arc welding is fusion welding in which heating is carried out by an electric arc. Has a large number of varieties.

Electroslag welding is a fusion welding process that uses the heat generated when an electric current passes through molten slag for heating. It is classified by the type and number of electrodes and by the vibrations of the electrode.

Electron beam welding is fusion welding in which the energy of accelerated electrons (electron beam) is used for heating. Classified by the presence and direction of beam oscillations.

Plasma welding is fusion welding in which heating is carried out by a compressed arc.

Light welding is fusion welding in which heating is carried out by a powerful light beam. Classified by type of light source (solar, laser, artificial light sources).

Gas welding is fusion welding in which the heat of the flame of a mixture of gases burned with a torch is used for heating. Classified by type of flammable gas.

Thermite fusion welding is a fusion welding in which the metal is heated by liquid thermite metal, which melts the metal of the parts being joined at the site of the welded joint formed over the entire cross-section and simultaneously serves as a filler metal.

Foundry welding is fusion welding, in which the prepared area is filled with liquid superheated metal, prepared in a container separate from the product.

 Combined welding

Combined welding - (thermomechanical welding class) welding carried out using thermal energy and pressure. The classification of combined welding is shown in Fig. 2.

Fig.2. Classification of combined welding

Resistance welding is welding using pressure, which uses the heat generated in the contact of the parts being welded when an electric current passes. It is classified according to a number of characteristics.

Diffusion welding is pressure welding, carried out due to the mutual diffusion of atoms in thin surface layers of contacting parts, achieved by heating (below the melting point) and prolonged exposure at this temperature, followed by compression. Basic classification by type of heating source.

Press welding is pressure welding with uniform heating of the metal (below the melting point) and subsequent compression with dies.

Furnace welding is pressure welding in which heating is carried out in furnaces or highlanders. It is divided into forge welding, rolling welding and extrusion welding.

HDF welding (high-frequency welding) is welding using pressure, in which heating is carried out by high-frequency currents. Heating can be induction or condenser.

Thermite pressure welding is pressure welding performed with heating of the metal at the site of the welded joint to a temperature close to the melting point, the products of thermite combustion reactions and subsequent precipitation on the press.

 Pressure welding

Pressure welding - (mechanical welding class) welding performed using mechanical energy and pressure. The classification of pressure welding is shown in Fig. 3.

Fig.3. Classification of pressure welding

Cold welding is pressure welding with significant plastic deformation (free or constrained) without heating the parts being welded by external heat sources. Classified according to the shape of the welded joint and the nature of the deformation.

Explosion welding is welding using pressure, in which the connection is made as a result of the collision of the parts being welded caused by an explosion. Explosion welding is close to cold welding, but differs in that in the joint zone the metal is heated uncontrollably as a result of rapid plastic deformation.

Ultrasonic welding is pressure welding, similar to friction welding, but carried out under the influence of ultrasonic vibrations. Classified according to the shape of the welded joint.

Magnetic-pulse welding is welding using pressure, in which the connection is made as a result of the collision of the welded parts caused by the influence of a pulsed magnetic field.

Source: http://weldworld.ru/theory/svarka/klassifikaciya-svarki.html

Methods, types and technologies of metal welding

Welding is used to obtain permanent joints of materials. It uses the principle of melting the edges of the surfaces being welded by thermal action. In addition to metal products, it is also used for other materials, including plastic. A welded joint is obtained by melting or using pressure.

Welding is performed by many methods, but only a few of them are most widely used. Numerous types of welding are used in general industrial production, in the repair of metal structures, in shipbuilding, aircraft construction, in a wide variety of areas of the national economy, in the space and military-industrial complex.

To familiarize yourself with the different types of welding processes, watch the corresponding videos provided.

Physico-chemical processes occurring during welding

When welding metal products in the working seam zone, a joint is obtained that is structurally different from the metal being processed. This occurs due to very complex chemical and physical processes.

During welding, an electric current passes through the joint, and the crystalline structure of the material begins to vibrate with the release of thermal energy. The transition of the electrode substance and the welded mass from solid to liquid occurs, mixing and crystallizing. During the welding process, deformations and internal stresses arise in the crystalline structure of the seam, as well as the adjacent area.

Chemical-type processes with various welding methods change the characteristics of the material, in which new compounds with different parameters arise. These include chemical reactions that appear in the liquid or gas phase, as well as at their periphery. In this case, slags, oxides and other compounds are formed that differ from the main material in the chemical composition.

Melting of the filler and welded product is performed using directed concentrated energy. For this purpose, a gas burner flame, a welding arc, or other methods of influence are used. The weld pool can be created by additional metal, as well as by the main material being joined.

It is mainly formed by mixing the filler element with the main element. In this case, additional material is fed into the welded area using a special wire, an electrode or another method.

By fusing and mixing, these elements create a common weld pool, limited by the melted boundaries.

The metal mass, molten under the influence of directed energy, goes through the crystallization stage and a strong connecting seam is obtained. Crystallization is the solidification phase of molten material. During the welding process, the base metal and the electrode metal are completely mixed under the influence of high temperature and form a single crystalline structure when cooled. This allows you to obtain a monolithic connection with very high strength.

Metal welding classification

Welding of various products is carried out using a huge number of methods. Their number reaches 200, which is far from the limit given the constant development of technology. Types of welding and classification of welding methods are very diverse. Their difference lies in physical, technological, and technical characteristics. The classification of welding methods according to physical properties is represented by three main groups:

• thermal;
• mechanical;
• thermomechanical.

The thermal processing method uses thermal energy. This group includes arc, gas, laser and other welding. Mechanical connections use the appropriate type of energy. The most commonly used methods include friction, explosion, and cold welding.

Each of these types differs in energy costs, special equipment used, and environmental friendliness. The thermomechanical group uses both thermal energy and additional pressure.

This welded type includes forge connection, diffusion, contact.

Main types

Various types of welding of metal objects consist of about twenty methods. They are united by a single physical process, which consists in heating and melting the metal in the connected zone. You can see the numerous welding equipment in the corresponding photos.

Electric arc

When using this type of influence, a welding arc is formed under a layer of flux between the electrode element and the material being welded. The metal mass begins to melt from the heat generated and turns into a liquid state. High temperature is generated in the welding arc at a small gap between the electrode rod and the material being processed. The temperature value can reach 6000 °C, which is quite enough to melt the product at the joint.

Upon completion of cooling, a seam is obtained that is almost as strong as the material being processed. A variety of this type includes the contact method, in which welding is carried out by creating intermittent fusion.

The electrodes used are specially marked for each type of material. The most convenient devices for this technology include inverters. A special type of electric arc welding is plasma.

Welding methods and types of welded joints using the electric arc method can be viewed in the video.

Electroslag

This type of process uses a slag bath heated by an electric current to create a melting region. In this case, the crystallization site is protected from hydrogen saturation, as well as oxidation. Melting heat is generated when welding electric current passes through molten slag (flux), which has good electrical conductivity.

After immersing the electrode in the slag bath, the electric arc goes out and the current begins to flow through the liquid slag mass. The connection is made by moving from bottom to top on vertical seams with a small gap along the edges of the parts. This type of welding is used for products with thicknesses from 15 mm to as much as 600 mm. In addition, this technology is used to produce castings, as well as to remelt steel from various wastes.

Gas-flame

The main heat source for this type of processing is the burner flame. To form it, a gas mixture with oxygen is used. The most commonly used gases include butane, acetylene, propane, and MAF. The treated surfaces melt simultaneously with the filler element. The flame power is regulated by the operator and depends on the amount of oxygen in the gas mixture. It can be reducing, neutral or oxidizing in nature.

Increased welding speed, as well as excellent quality of seam joints, are obtained when using MAF. This name refers to the methyl acetylene fraction. However, it requires special wire with a large amount of silicon and manganese, which significantly increases the cost of the process. Types of welding and their brief characteristics using the gas-flame method are shown in the corresponding video.

Plasma

The energy for this type of processing is obtained from ionized gas - plasma. This is a non-standard form of welding work. Plasma technology uses special devices - high-frequency and arc-type plasmatrons.

For metal and steel alloys, direct action units are used, and semiconductors and dielectrics are welded with indirect action devices. In a special chamber of the plasmatron unit, the working gas is heated by special eddy currents, which are created by a high-frequency inductor.

The absence of electrodes makes it possible to use a high-purity plasma torch.

Electron beam

In electron beam welding, heat is created by a powerful flow, which can be either electron or photon. It has energy of enormous significance. At high speed, the particles hit the product and transfer their energy power to its atoms.

In this case, intensive heating of the joint of the welded elements is performed. The procedure is performed in a vacuum area, which improves the quality of the welded joint. An electron beam can be formed to microscopic sizes, reaching several microns.

Welding of micro parts is possible using exclusively this technology.

Laser

Processes using laser equipment are characterized by ease of control, ease of implementation, complete control over the localized processing area, and the absence of mechanical impact.

A small laser beam makes it possible to carry out many operations on parts made of easily deformable materials, as well as near elements with high sensitivity to thermal effects. The connection with this method is obtained by local melting of sections of the products.

The disadvantages of this process include the need to use a special control system and technological features, which greatly reduces the efficiency, as well as the cleanliness of welding when processing energy-intensive products.

Process automation

Some types of work where welding is carried out on a large scale require an automatic installation. It supplies clean electrode wire, as well as granular flux, to the area to be welded.

In this case, the arc moves along the length of the welded joint, and stable arc combustion is maintained in automatic mode. Submerged arc welding in automatic mode is used for metals of critical components with a thickness of up to 10 mm.

In addition, automatic devices are used in production when producing similar elements in large quantities.

The productivity of this process is much higher than the use of manual welding. This technology makes it possible to process metal objects with a joint size of joined elements up to 20 mm without preliminary cutting of the edges. At the same time, there is also a drawback, which consists in the limited maneuverability of the units, in which welded surface treatment is carried out in the lower position.

The use of semi-automatic submerged arc welding machines is optimal for products with a small radius of curvature, short joint lengths, as well as for hard-to-reach areas. In this process, the device solely performs the feeding of the electrode welding wire into the work area. The arc is moved along the connecting seam by the welder himself, using a special electrode holder. Semi-automatic machines are used in small-scale production and individual production of parts.

Requirements for welding seams

Connections of materials that are obtained using welding are required to ensure reliability as well as operability of the structure. Strength and endurance should not decrease over time and guarantee the safe use of parts and structures. For these reasons, requirements are imposed on the quality of welded joints that directly depend on the purpose of the parts. In addition to general provisions, special standards are used that establish specific parameters for welding joints.

Increased demands are placed on seams that are constantly under the influence of high tensile stresses (beams, walls, trusses). Average level indicators apply to butt joints that resist shear, tension, and corner joints when welding main structural parts. Low requirements are placed on corner and butt seams of auxiliary structural elements.

Source: https://oxmetall.ru/svarka/sposoby-svarivaniya-metallov

Features and characteristics of welding types

The life of a modern person is closely connected with things made using welding technologies. We are talking not only about joining metal, but also other materials that can be joined at the molecular level. The article will discuss the main types of welding.

Process concept

Welding is a technology for creating a permanent connection between two surfaces through intense temperature exposure.

Physical signs

Metals have a high melting point. Without additional area factors, the contact parts of the welded products will not interact with each other. To change the state of aggregation of a metal, it is necessary to increase its temperature. Upon reaching a certain level, conditions are created under which it becomes possible to join parts to obtain a strong interatomic bond between the surfaces.

Manufacturability is the main property of welding work

The types of welding used depend on the characteristics of the work parts, as well as production conditions. The most commonly used technologies are:

• Dugovaya.
• Plasma.
• Gas.
• Pressure welding.
• Butt.
• Cold.

Importance of properties

In the process of joining workpieces, it is necessary to ensure reliable protection of the temperature-affected zone from the aggressive influence of oxygen in the atmosphere . Otherwise, corrosion processes will actively develop in the processing area, deteriorating the quality of the structure. The main ways to prevent contact of the melt with air:

• flux;
• vacuum;
• protective gases;
• foam.

Classification

The classification of metal welding is carried out based on the nature of the impact on the plane:

1. Thermal class . It is characterized by a non-contact method of influencing the surface - an electric arc or a gas flame.
2. Thermomechanical class . This type of welding combines non-contact action to achieve the desired temperature, as well as mechanical pressure to complete the connection.
3. Mechanical class . The specified thermal parameters are obtained solely through mechanical action on the products being connected.

Below we will discuss the types of welding and their brief characteristics for each class.

Welding arc

A welding arc is a source of thermal energy for molten metal . It is an electrical discharge that occurs when a circuit breaks. Devices operating on direct or alternating current are used as a power supply mechanism.

Manual arc

The work is carried out using flux-coated electrodes and a welding machine . The method got its name due to the functions performed by the welder:

• Selecting the direction of movement of the rod and its speed.
• Arc length;

When exposed to high temperatures, the flux melts. Some components enter the melt zone, improving quality characteristics, while others remain on the surface, forming a protective film.

Non-consumable electrode

Refractory elements are used as electrode material: tungsten or graphite . The melting point of the base surface is lower than that of the electrode. This circumstance increases the service life of the rods. The use of filler metals is acceptable. Due to the absence of flux, work is carried out in an inert gas environment.

Mechanized with a consumable electrode in a protective gas environment

This type of work is characterized by the use of a special filler material - electrode wire, the composition of which depends on the properties of the working surface . Feeding mechanisms are used to feed material into the welding zone.

They can be either one of the units of the unit or stand-alone equipment. The wire does not have a protective coating, so the connection is made under gas protection. In its absence, a special type of additive is used - flux-cored wire, which contains flux to protect the seam.

For work, devices that operate in semi-automatic mode are used.

Submerged

In this case, a flux composition is applied to the joint zone, which, when melted, creates a gas bubble that serves as a barrier to harmful atmospheric factors . Complies with the requirements of GOST 8713-89. In serial production there are installations that perform submerged arc welding in automatic mode.

Orbital

A method for industrially joining circular surfaces such as pipes . There are two ways to implement permanent communication. In the first case, the workpieces rotate around their axis. Under the influence of friction force, the operating temperature is reached. In the second case, the products are fixed, and the movable head of the arc welding machine rotates around them. In this case, electrode wire is used.

Reflow butt method of joining plastics

As the name suggests, a Teflon-coated heating element is used to melt plastic products.

With embedded heaters

Another method of joining polymers. Heating is carried out by resistance elements that are installed on the coupling. After mounting the workpiece, an electric current is applied, melting the plastic.

Kuznechnaya

A forging hammer was used as a working tool, deforming workpieces . Is the oldest way to perform a connection. Currently practically not used.

Contact

The most popular method of this class. The work cycle includes two stages. The first is melting the surface to a plastic state. The second is pressure on the heated elements, which can be carried out either manually or using various drive mechanisms. Subtypes of contact technology are:

Spot

A popular technology that can be implemented at home. The product is placed between two rods that act as electrodes. They are supplied with a short-term pulse charge, which heats the plane. The workpiece is then compressed by electrodes, forming an interatomic compound.

Butt

The main difference between the technology is the width of the impact on the surface. The connection is made along the entire contact plane. There are two ways to create a connection:

• resistance;
• continuous reflow.

Embossed

The method is characterized by specific preparation for welding. Elevations called reliefs are pre-installed on the contact planes . After joining the points, an electric current is applied to them, which causes deformation of the reliefs.

Diffusion

The technology is based on the phenomenon of diffusion - the mutual penetration of particles into each other . As the temperature rises, the intensity of atomic movement increases, creating optimal conditions for connecting parts. The process takes place in an airless environment or in a protective gas environment.

High frequency currents

The metal melts under the influence of high frequency currents. After crystallization of the treated area, a strong weld is formed.

Friction

The main advantage of this joining method is the ability to work with dissimilar metals . According to technological requirements, one workpiece must be securely fixed in a special support. The second one is spun around its axis and connected to the first one under pressure. The thermal energy released due to friction is sufficient for the formation of new molecular bonds.

Explosion

The main method for producing bimetallic compounds. To sinter blanks, thermal energy is used, which is released during an explosion.

Ultrasonic

This method uses ultrasonic vibrations to form permanent bonds between atoms . The uniqueness of the technology lies in the ability to weld various materials, from metal to leather or glass.

Cold

A unique method of welding materials, which is characterized by a low operating temperature, below the level of recrystallization of the metal structure . Technological requirements include careful preparation of the working plane. It must be cleared of foreign elements. Immediately before the start of the cycle, the surface is degreased.

This pressure welding is used to work with materials that are sensitive to temperature changes.

International designations

When performing work in Russia, in construction and other industries, all welding processes are subject to the requirements of GOST R ISO 4063-2010. This is a domestic analogue of the international standard ISO 4063:2009.

In art

Artistic welding is a recently emerging art direction . A master who creates sculptural compositions is called an art welder. In Moscow and other large cities, numerous exhibitions are held that introduce connoisseurs to new works.

It is safe to say that every year more and more people are interested in artistic metal welding.

Conclusion

The article explained what types of welding there are: from electric welding to ultrasonic joining.

Source: https://svarka.guru/vidy/osobennosti-i-harakteristiki.html

We study the main types of welding

Welding is called a technological process for creating unity between two connected welded parts using interatomic interaction that occurs through a heating operation (general and local), plastic formation or the unification of these two components. Today there are many types of welding (the number of types is close to 100), the characteristics of which can be classified into physical, technical and technological varieties. Let's look at each in more detail.

The importance of technological properties

Technicality is provided by:

• security of the metal component in the weld;
• uninterrupted processes;
• mechanization of the welding process.

The main types of welding are:

• air;
• vacuum;
• protective gas;
• under flux;
• by flux;
• foam;
• combined - protective.

Depending on the nature of replaceability. What types of welding can help us? It is possible to replace the protective gas with active gases (carbon dioxide, nitrogen, hydrogen, water vapor and a mixture of active gases) - mig, inert gases (argon, helium and their mixture) - mag and a combination of active and inert gases.

Melting of a metal object is divided into jet and controlled-atmospheric. Jets promote a protective reaction of the molten substance on the welding shank. They are characterized by one-sided actions, which is why they are named as such. If the protection from the welding bow is with the root of the seam, then it is double-sided with the same name.

Continuity nature of operations. Includes types of fusion welding, consisting of continuity and discontinuity.

Advantages of the Arc Welding Process

The arc operation is considered the most used type of welding. Such types of welding are necessary for both industrial and domestic areas.

The purpose is to melt the substances being welded using heat generated by electric arcs. Following the act of solidification comes the unity of the elements.

There is a need for high current power supply operating at reduced voltage. An electrode wire is attached to its clamping mechanisms for touching the part to be welded.

Let us dwell on the subtypes of electric arc welding work. They are:

1. Manual . The advantage is to carry out work with a spatial position of any degree of complexity. Using a special electrode coated with flux. The coating is necessary to protect metal seams from the influence of external factors. The welding process is carried out using direct current with direct or reverse polarity, as well as alternating current (MMA welding). This facilitates the use of short and curved seams in places that are difficult to access.
2. Under the influence of a non-melting electrode element . A graphite or tungsten rod is taken in the form of an electrode. The welding operation is carried out with the participation of inert (mig) and active (mag) gases;
3. When exposed to a melting electrode . A wire made of steel, copper or aluminum is used as an electrode substitute to supply current through a conductive tip. An electric arc melts the wire, activating the mechanism (MMA melting);
4. Submerged . The process is almost similar to the previous one, but the action is carried out by flux;
5. Electroslag . The heat source is considered to be slag through which current moves. This method is acceptable for thick-walled structures.

Welding is also affected by the flame, which varies depending on the oxygen pressure. If it is large, then welding does not occur, but the materials roll off from the weld pools. The types of welding flame are also varied. They are divided according to the principle:

1. Reduction that occurs when oxygen reacts with acetylene.
2. Oxidation that occurs during the interaction of large oxygen volumes.
3. Carburization, which occurs at a low ratio of oxygen to acetylene.

Gas shielded welding

Let us dwell in more detail on a type of electric arc welding process in which melting is carried out in a protective gas environment. Gaseous substances are divided into inert and active. And methodologically, welding work is divided into instant and magic varieties.

The main significance of the method is the versatility of the use of the material, which is taken from a combination of mechanization degrees and welding positions.

The nature of welding under the influence of shielding gases allows a similar operation to be performed for welding all materials that can be welded (MMA welding).

The unalloyed and alloyed nature of the steel raw material facilitates welding in an active shielding gas, for example, carbon dioxide. This process is called "active gas welding" or mag for short (metal chemical welding process under the influence of active gases).

High-alloy steel and materials like aluminum, magnesium, nickel alloys, and titanium undergo melting under the influence of inert gases (for example, argon). This process was called "inert gas welding" (mig).

Methods for reducing stress and strain

The stress and strain need to be reduced somewhat. This is possible using thermal, mechanical and thermomechanical methods.

The parts are machined with processing, which also reduces the properties of the crystal lattice.

Metal rolling - the effectiveness of the method. But we can only implement it at the enterprise. Available and simple - the forging method, where the hot seam is subjected to impact treatment, removing the residual stress of MMA.

The third includes a combination of thermal and mechanical species categories. By taking the most advantageous properties, they achieve maximum efficiency.

Types of welding seams

Welding seams come in several types, depending on the following parameters.

Method of holding molten metals

• underlays made of copper, ceramics, asbestos, flux, gas, etc.;
• unlined.

Overlay side

• one-sided;
• bilateral.

Weld joint material

• for carbon and alloy steel;
• non-ferrous metal;
• bimetal;
• vinyl plastic;
• polyethylene.

Arrangement of parts one to another

• acute-angled;
• obtuse-angled;
• rectangular;
• single-plane.

Metal volume

• normal;
• weakened;
• strengthened.

Welding connections

Welded – a permanently connected part, divided into:

• butt;
• corner;
• overlap;
• T-bar;
• end

Butt joints are a combination of single-plane or single-surface end parts. The size may be similar or different. Application: for welding pipes and tanks.

Corner – a combination of corner elements. Widely used in construction.

Overlapping – providing for the overlap of two components of a partially overlapped type, located in the same planes.

T-joints are called connections with the arrangement of two end parts in a certain melting manner.

Source: https://electrod.biz/vidy/osnovnyie-vidyi-svarki.html