Types of metal welding

Today, various types of metal joining are used, the main differences and characteristics are divided into technical, physical, and technological varieties. The technological process of joining involves the interaction of materials at the interatomic level through the influence of temperatures. Fixed fasteners are used for a variety of materials, the main ones are metal parts, glass, plastic and ceramics are also welded. The process takes place in the main ways manual, semi-automatic or automatic, depending on the characteristics of the mechanisms.

Types of welding

Content

The concept of the welding process

Physical signs of welding

Manufacturability is the main property of welding works

The importance of technological properties

Classification of welding methods

Thermal welding class

Arc welding

Gas welding

Beam welding

Thermite welding

Electroslag welding

Thermomechanical welding class

Forging welding

Contact welding

Diffusion welding

Mechanical welding class

Friction welding

Cold welding

Explosion welding

Ultrasonic welding

The concept of the welding process

The energy is supplied to the electrode, the welding material, by amplification through an inverter. The definition of welding begins with the fact that the impact of an electric arc leads to the melting of the metal of the electrode, which leads to the formation of a welding bath. During the formation of the bath, mixing with the base material occurs, the slags float to the surface and serve as a protective film. The solidification of the metal after the processes is called the welding process.

Welding process

To determine what welding is, it is important to know that there are two types of electrodes – non-melting and melting. A non-melting electrode implies the use of a filler wire, which is introduced into the welding bath separately. The second option melts the electrode rod directly. Protection against oxidation during the docking process is produced by gases supplied during the gorenje head. There are variable and constant aggregates, when working with DC aggregates, a better, uniform seam occurs.

Physical signs of welding

The interaction of metals or other materials occurs through the interatomic action of elements. At normal temperature values, the materials do not interact with each other regardless of the conditions, due to the solid structure of the metals. Contamination of surfaces during the connection in the form of fat formations or oxides has a significant impact during the metal bonding process.

Under the influence of compression, a physical connection on the surface or plastic deformation is possible. Atomic-metal bonds occur through the interactions of electronic compounds during the welding of metals, as well as the docking of covalent metals. The type and type of welding is determined by several parameters of interpenetration, for example, compression, desoldering and thermomechanical action.

The melting of the material occurs without the influence of external mechanical forces, the necessary temperature is provided by welding shackles, gas flame, and other energy sources. Types of welding operations under pressure imply the deformation of the metal, which gives fluidity to liquid compounds. The process of joining materials occurs due to the influx of fresh layers of material on top of each other.

Manufacturability is the main property of portable welding machine works

There are many varieties of methods, types of welding work. The classification is directly dependent on the type of material and equipment. Common types of welding work:

electroslag;

arc;

plasma and electron beam;

light, gas;

ultrasonic;

cold, stove, contact types.

Plasma welding

Electroslag welding

The importance of technological properties

Technological properties ensure the continuity of the process and its mechanization. The metal component in the weld remains protected if the requirements and technologies are met. Types of welding are divided into:

vacuum pumps
air
protective-gas
by flux
foamy

under the flux types.

The degree of the molten medium of the material is divided into atmospheric and jet varieties. The molten substance on the arc of the weld characterizes the jet technology. The nature of the substitutability contributes to the possible replacement of the gas with a more or less active one. There is a set of active or inert gas compounds. The degree of mechanization is divided into manual, mechanized and fully automatic process.

Classification of welding methods

The main ways of creating welding seams are three main types of welding. The melting of elements without applied force or pressure is applied to equipment capable of operating with an electric arc or a gas flame. The molten metals are combined in the welding bath, forming a protective layer on top of the parts to prevent oxides and interaction with oxygen.

Electric arc welding

The thermomechanical type of connection implies the use of pressure and thermal energy. Heating of the workpieces of the elements is carried out at the expense of thermal energy, mechanical force gives the desired connection to the plastic metal. The classification of welding has a third type, in which pressure is applied to parts of materials. As a result of the actions, the material is liquefied, becomes fluid, which makes it possible to connect the materials in hard-to-reach places. The contaminated layer is removed to the surface of the fluid, resulting in an updated layer, a clean seam.

Thermal welding class

This class of welding works is performed by melting the edges of parts of materials. At the beginning of the process, a welding bath is formed, after which the seam is removed. The classification of types of welding by thermal method is divided into the main subcategories:

gas station
electron beam
plasma
laser
thermite
electric arc docking.

The most common is the last option because it does not require specialized tools, devices.

Arc welding

Electric arc joining of parts is most popular during the work. The electric arc between the electrodes is produced by a powerful discharge, one of the elements is the welding process.

Arc welding scheme

The work is carried out after processing, preparation of the material, consists of the main stages.

The electrode comes into contact with the metal, which causes a short circuit, after that, the tool is withdrawn to a distance of no more than 5 mm. A short circuit is used to achieve the required temperature by the electrode, by intense electron emission in the cathode structure. After reaching a stable, stable arc, work is performed.

A stable arc charge is produced by accelerating electrons in an electric field, ionization of the gas connection of the anode with the cathode occurs. The temperature of the electric arc as a heat source reaches up to 6000⁰. The welding current at an arc voltage of up to 50 V, using a special coated compound, reaches up to 3 kPa.

The purpose of this type of welding using coated electrodes is to dope the composition of the seam, protect the melt from environmental influences by the gas and slag method.

Gas welding

Electric arc method, in which the process is carried out in a gas protective environment. Gaseous substances are divided into inert and active types.

There are several types of MIG and MAG welding methods, the main purpose is to use universal materials, they differ in mechanical parameters.

Before using the equipment, it is necessary to check all the components, clean the processed metal from paint and rust.

The device of the device for gas welding

The set of gas welding equipment consists of:

oxygen hose with a nominal pressure of 0.64 MPa, used to supply acetylene;

oxygen is supplied through a third category hose with a pressure of up to 2 MPA;

two reducers for pressure adjustment;

cylinders with a volume of 40 liters or more;

a burner with an adjustment screw.

The acetylene supply pressure is adjusted by adjusting the reducer on the cylinder, a special pressure gauge indicates the exact parameter. The pressure of the combustible mixture should be about 0.2 MPa, oxygen is regulated in an identical way to the level of 0.5 MPa. The gas burner is adjusted by opening the acetylene supply until the fire is stabilized at the base, the flame power is set by oxygen.

The main components of the flame are the core, the recovery zone and the torch. The burner is located at a certain degree to the base metal, the distance between the core and the material is 1.5 mm. The metal is heated up to the melting point by translational movements, after which the degree of supply of the burner changes, the filler wire is fed.

Beam welding

High seam quality is achieved by working in a vacuum. The process is the transfer of a powerful beam of energy to the workpiece. The electrons interact with the constituent substances of the material, which leads to rapid heating, reaching the required melting point. This category of welding works is used when working with trace elements, since the beam can be adjusted to the size of a micron in diameter.

Installation for beam welding

Electric beam welding scheme

Thermite welding

Welding takes place using a special material – thermite, consisting of magnesium or aluminum compounds, iron scale. The powdered mixture will be applied to metals prepared in a heat-resistant form of the material, pre-igniting with a fuse or an electric arc. The result is a strong connection, the main purpose of this type of work is the joining of pipes, rails, surfacing of massive products.

Electroslag welding

A relatively new method of performing welding works has been developed at the Institute. Paton. The prepared parts are enveloped in slag, which is heated to temperatures exceeding the melting of wire and metal. Electroslag welding allows you to fill large gaps in one pass, the process does not differ from the arc type of metal joining. The high quality of the seam is achieved due to the formation of a protective bath, which pushes unstable metal compounds to the surface.

Diagram of the electroslag welding process

The process of electroslag welding occurs as follows:

the edges of the vertically arranged parts are inclined by 20-25⁰ in relation to the marked part;

the necessary gap for placing the powder is set;

the arc ignited between the lower plate and the electrode located on top melts the flux;

the slag bath occurs by melting the flux, copper sliders, after which the shunted arc goes out;

there is a transition from the arc type to the slag type, the bathroom of which is heated to 1700⁰;

the edges of the metal are melted by slag in the welding bath, after removing the electrode, the metal cools and crystallizes.

In this way, it is possible to work with complex seams, large-sized parts. The increased quality, the absence of cracking, allow you to join the critical parts with slag welding.

Gas impurities and bubbles are removed without difficulty from the welding zone, this is facilitated by the vertical location of the structure.

Thermomechanical welding class

The combined method offers the effect not only of increased temperature on the metal, but also mechanical forces. In most cases, it is used when joining small-sized parts that are not possible to connect qualitatively in the usual way. The process takes place in sponge electrodes, in which two parts of the parts are fixed. The main types of welding are called contact, diffusion and forging methods.

Forging welding

A high-quality connection by the forging method of work is achieved under the conditions of the attached surfaces cleaned of deposits, oxides. The work with a hand tool is carried out on heated metal, the parts are overlapped and hammer blows are made on the surface.

Methods of forging welding

Forging welding

The forging type of welding is not applied to all materials, has low productivity, requires sufficient experience from the blacksmith.

Modern types of work have replaced blacksmithing due to the low reliability of the joined parts.

Contact welding

Heating during resistance welding is achieved by fitting the needle surface to the product. The electric current passes through the tool of the desired diameter, it is necessary to prepare the metal first by squeezing or sedimentary mechanical action. The chemical effect of metal atoms makes it possible to weld small parts, it is easy to automate and is high-performance.

Contact welding

It is divided into three main methods, point, roller and butt varieties. It is widely used in industry and mechanical engineering, in hard-to-reach places and connections.

Diffusion welding

The basis of the method is the use of atom diffusion at a high vacuum level. The surface layers of the metal are heated due to the high diffusion capacity of the atoms to temperatures close to melting. Contact and reliable docking occurs by mechanical action of high force, the minimum compression power is 20 MPa.

This type is used for poorly contacting materials.

The process begins with placing the parts in a special chamber, fixing and transferring the force. The materials are kept for a certain time, under the influence of an electric current.

Mechanical welding class

Types and methods of mechanical welding use physical impact on the materials being joined. The main methods have advantages in the absence of the possibility of reaching the melting point. The transition of energy from mechanical to kinetic allows you to heat the joined products to the melting threshold.

Friction welding

The main parts to which friction welding is applied are pipes of small diameter, rod structures. The automated process allows you to perform various types of welding operations in special machines, in the spindle of which the workpieces are attached. The machine works by moving one of the parts to a stationary part. The rotation speed is brought up to 1500 rpm, as a result of which the parts are heated and melted.

After turning off the rotation clutch, the machine performs the precipitation of the products. Cost-effectiveness, fast execution of tasks, make the type of friction work preferable to arc work, and it is also possible to cook metals from different alloys.

Cold welding

The workpieces are joined by cold welding by deforming the plastic properties of the materials. The temperature during the operation can reach minus, the surfaces must be cleaned from oxides and rust. The connection takes place at the interatomic level, so the elements must be perfectly smooth and processed.

Cold welding

A cold look is used when joining tires, wires or pipes. The pressure varies from 1 to 3 GPa, this method requires equipment prepared for high loads.

Explosion welding

The connection of parts during explosion welding occurs by synchronous plastic deformation of parts. The movable part of the part is applied in parallel to a stably fixed target, after which a controlled explosion is produced. The main application of this method was due to the possibility of joining dissimilar metals. Explosives are used from the composition of granulotol, ammonite, rdx.

Explosion welding

Ultrasonic welding

The parts are joined using energy sources that emit ultrasonic vibrations at the output. It is used for seam, spot, contour welding by mechanical action. Dry friction contributes to the destruction of oxide films, after which it is replaced by pure friction, at which the welding process takes place. The main advantages of this method is the absence of pre-cleaning of surfaces, which significantly saves time. When welding plastic parts, overheating of the attached zones is not allowed, since the temperature range of a certain area is controlled. There are no harmful vapors, gases during the process, heating occurs in a fraction of a second.

Ultrasonic welding

The disadvantages of ultrasound can be distinguished by expensive equipment, a small range of thickness of materials. It is necessary to clearly determine the thickness of the types of materials to be welded, with dimensions outside the tolerance, it is possible to use an acoustic lens, which makes it possible to focus energy on a certain part of the part.