The main methods and types of soldering. Soldering equipment, materials and soldering technology. Technology of welding-brazing of metal structures made of galvanized steel Soldering welds in a short time

Soldering is one of the most well-known methods for joining metals. However, the soldering methods used until recently due to low productivity, insufficient connection reliability, complexity technological process and other shortcomings were used relatively rarely.

AT recent times new soldering methods have emerged that use different kinds electric heating: t.v. hours, electron beam, heating in thermal furnaces, ultrasonic soldering, etc. These heating methods, in combination with protective media such as vacuum, inert and reducing gases (hydrogen, CO, etc.), special solders that do not require fluxes, allowed to significantly improve the quality of brazed products and increase the productivity of the soldering process.

New soldering methods make it possible to use the part in products without subsequent machining.

Using new soldering methods, it is possible to join refractory metals and metals with special properties.

Thin-walled structures exposed to high temperatures can be fabricated from such metals under vacuum conditions. soldering in state of the art meets all the requirements of production in terms of economics, since the use of solder joints helps to reduce labor intensity and reduce the cost of the product.

Soldering has become one of the most important technological processes for joining metals in many branches of the metalworking industry. Soldered joints work reliably in critical products in aviation, radio engineering, automotive, instrumentation and other industries.

Soldering is the process of obtaining a permanent connection of materials with heating below the temperature of their autonomous melting by wetting, spreading and filling the gap between them with molten solder and their adhesion during the crystallization of the seam.

Soldering of metals should be carried out at a certain temperature and in environments that ensure good wetting of the metal with solder and mutual diffusion of the liquid solder and the metal of the product to be joined. In this case, conditions must be created for the occurrence of capillary phenomena. The latter ensure the penetration of liquid solder into the gaps between the connected products. The solder penetrates into the gaps between the parts to be joined, crystallizes upon cooling and forms a strong bond. You can heat the product and melt the solder with an arc, heat released in electrical contact, in resistance furnaces, by induction, by an electron beam, by a gas flame, by immersion in salt baths or liquid solders, etc.

Soldering has a number of advantages over welding. In many cases, soldering uses less heat. Soldering does not cause significant changes chemical composition and mechanical properties base metal. As a rule, residual deformations in brazed joints are much less than in welded ones. Therefore, it is possible to maintain the exact dimensions of brazed structures without additional processing. Soldering connects carbon and alloy steels, cast iron, non-ferrous metals and alloys, noble metals, etc., as well as dissimilar materials. The soldering process is easily mechanized and automated.

Most soldering methods are carried out using various solders, and only in cases where fusible eutectics can form between metals during soldering, soldering is possible without special solder.

Solders are subject to a number of general requirements. The solder should spread well over the surface of the base metal, wet and dissolve it, easily fill the gaps between parts, provide the necessary joint strength, etc.

Solders are used in the form of tapes, pastes, rods. Solders are especially common in the form of wire loops and foil spacers, stamped in accordance with the surface of the parts to be joined.

Widely used as solders are high-temperature solders - alloys based on silver, aluminum, copper, etc., which, as a rule, have a melting point above 450-500 ° C (723-773 K). Copper-zinc solders PMC 36, PMC 48, PMC 54 have a tensile strength σ in = 21 35 kgf / mm 2 (206.0 - 343.2 MN / m 2), elongation up to 26%, recommended for soldering copper products , tombac, brass, bronze. Silver solders have a melting point of 740-830° C (413-1103 K). According to GOST 8190-56, solder grades are divided depending on the content of silver in alloys, which varies from 10 (PSr 10) to 72% (PSr 72). They also contain zinc, copper and a small amount of lead. These solders are used for soldering thin parts, joining copper wires and in cases where the solder point should not drastically reduce the electrical conductivity of the butt joints.

Low-temperature solders have a melting point below 450-400°C (723-673 K). They have little strength. They are used for soldering almost all metals and alloys in their various combinations. In most cases low temperature solders contain a significant percentage of tin.

Low-temperature tin-lead solders (GOST 1499-70) have an upper critical melting point of 209-327 ° C (482-600 K). Tin has a melting point of 232°C (505 K). Its tensile strength is 1.9 kgf / mm 2 (18.6 MN / m 2), relative elongation is 49%, HB is 6.2 kgf / mm 2 (60.8 MN / m 2). Tin-lead solders POS-90, POS-61, POS-40, etc. are used for soldering copper devices, aircraft radiators, brass and iron products, copper wires, etc.

The formation of a high-quality brazed joint largely depends on the possibility of the most complete removal of oxide, adsorbed gas and liquid films from the metal surface. In the practice of soldering, various kinds of fluxes, a reducing atmosphere or vacuum are used to remove surface films. Recently, mechanical destruction of films using ultrasonic elastic vibrations has been successfully used for this purpose.

Soldering fluxes have several purposes. They protect the base metal and solder from oxidation, dissolve or reduce the formed oxides, improve wetting of surfaces, promote the spreading of solders. Fluxes can be used in solid, liquid and gaseous form (in the form of powders, pastes, gas solutions). The role of the flux is performed by some special gas atmospheres and vacuum, which can also contribute to the reduction of oxides and improve wetting conditions. In some cases, the fluxing effect is exerted by the individual components that make up the solders. For example, phosphorous solders do not require fluxes when soldering copper alloys.

Soldering can be carried out with general or local heating of the structure. With general heating, the product is placed in an oven or immersed in a salt or metal bath. Under these conditions, the product warms up evenly. This process is suitable for soldering products of relatively small sizes. With local heating, only a part of the structure in the weld zone is heated.

Soldering with a soldering iron. The most well-known and widely used low-temperature soldering method is soldering with soldering irons. In improved designs of soldering irons, a mechanized supply of solder and its dosage are provided.

Soldering with a gas flame. Gas flames are soldered manually and mechanized. The source of heating is the flame of conventional burners using a relatively low-calorie gas, such as propane, as a fuel. The gas flame only partially protects the junction from oxidation, so the use of fluxes and pastes is recommended.

In some cases, fluxes are fed in the gaseous state directly into the flame. With gas soldering, it is possible to use high-temperature and low-melting solders.

For large parts, a soldering process called "bronze welding" is sometimes used. In this case, brass rods serve as solder, the product is heated with an oxygen-acetylene torch. First, the edges are heated with it, flux is poured, they are tinned with a thin layer of solder, and then the entire volume of cutting is filled with solder. Bronze welding is used in the repair of cast iron and steel parts.

Soldering operations are quite common not only in professional fields in production and construction, but also in everyday life. They are used to obtain interatomic between small parts and elements. Exist different types soldering, differing in technological nuances, used consumables, blanks, etc.

General information about technology

This is a joining method that uses a bonding melt (solder) with characteristics suitable for specific conditions. Both the active soldering element and the workpieces are subjected to preheating, which forms a structure of materials that is malleable for joining. The temperature regime must exceed the peak heating point, bypassing which the metal parts soften and begin to transition to a liquid state. An important characteristic any kind of soldering is the thermal exposure time under the melt. This is the interval from the start of heating to the hardening of the solder after the connection is made. On average, the operation takes 5-7 minutes, but there may be deviations from this range - it depends on the characteristics of the workpiece and the area of ​​the processed unit.

Soldering lamps

The most common tool for soldering various workpieces, which allows you to get high-temperature heating by burning alcohol, kerosene and other types of liquid fuels. In the process of operation, a flare fuse escapes from the nozzle of the apparatus, which is subsequently directed to the target area of ​​the melt. Such devices can be used not only for joining parts, but also for heating structures and mechanisms. Also, soldering machines are used before removing paintwork. The average heating temperature of a lamp soldering iron is 1000 - 1100 ° C, so it can also be used in welding. The most productive models include gasoline lamps. They quickly reach optimum operating temperature and handle most standard soldering operations. The design of the devices provides for a cartridge for fuel, as well as a flame regulator that allows you to vary the power of thermal exposure.

Soldering torches

wide group gas soldering irons, which can be connected to a fuel canister or to a central source of fuel. The first supply option has the advantage of autonomy. A burner with a spray can, as well as can be used regardless of external communications. When choosing such a device, one should take into account the power, operating temperature, type of gas used, ready-to-work time, etc. For example, a standard gas soldering torch runs on propane-butane and reaches a heating temperature of up to 1300°C. The period of continuous thermal exposure can reach 3 hours, but this time will also depend on the volume of the connected cartridge. Burners are also distinguished by the type of ignition system. The simplest models are switched on mechanically, and in more modern modifications, piezo ignition is used.

Electric soldering irons

It is also a common type of soldering equipment in the domestic environment, which is safe (compared to gas appliances) and compact in size. But it is worth emphasizing the shortcomings as well. Firstly, such devices are dependent on the mains, which limits their scope. Secondly, electric soldering equipment maintains a low heating temperature in the range of 400 - 450°C. This is due to the fact that part of the energy is lost in the process of converting electricity into heat.

When choosing a device, the maximum voltage must be taken into account. So, in workshops and industries, standard 220 V models are used. In domestic conditions, devices operating from 12 and 24 V transformers are often used. Tasks that can be solved with electric soldering irons are mainly limited to repairing small equipment, restoring microcircuit contacts, connecting plastic parts, etc.

Soldering stations

To perform batch or in-line soldering operations, multifunctional equipment is used. The soldering station has a wide range of adjustment options for operating parameters, as well as higher heating temperatures. Suffice it to say that devices of this type operate at a power of 750 - 1000 W, connected to networks with a voltage of 220 V. As a rule, these are professional soldering equipment, but there are also household counterparts. For example, devices for group operations at home may include several interchangeable tips of different sizes, stands, desolderers, wire cutters, and other auxiliary accessories. Now it is worth getting acquainted with different technological approaches to soldering processes.

The main types of soldering

There are techniques for performing operations on the joint and clearance. So, if the gap between the connected elements is less than 0.5 mm, then the soldering will be with a gap. Exceeding this interval means that the connection is made end-to-end. Moreover, the joints can have different configurations - for example, X- and V-shaped. Gap soldering is performed only with liquid solder, which is sent to the intermediate zone during operation. butt soldering involves filling free space with solder under the influence of gravity.

Classification of soldering by temperature conditions

To date, soft, hard and high-temperature soldering is used, which is used mainly in manufacturing and construction. The first two techniques are similar in many ways - for example, in both cases, the operating temperature is 450 ° C and below. For comparison, high-temperature connections are made in the mode of at least 600°C, and more often - above 900°C.

At the same time, low-temperature processing can provide a high-quality connection. The most advantageous will be the use of hard solder, due to which high strength and refractoriness of parts are achieved. Adding copper to the gap or joint will also increase the ductility of the workpiece. If it is required to obtain a flexible and elastic structure, then soft soldering is used.

Solder classification

It is conditionally possible to divide modern solders into two groups:

• melting at low temperatures.
• Melting at high temperatures.

As already noted, low temperature soldering is performed at 450°C and below. The solder itself for this kind of operation should already soften at 300°C. Such materials include a wide group of tin alloys with the addition of zinc, lead and cadmium.

High temperature melt media are used for soldering at temperatures in the order of 500°C. These are mainly copper compounds, which also include nickel, phosphorus and zinc. It is important to note that, for example, in addition to a lower melting point, it will differ from copper alloys in mechanical strength. The ratio of resistance to physical pressure can be represented as follows: 20 - 100 MPa versus 100 - 500 MPa.

Types of fluxes

When exposed to heat, an oxide coating is formed on the surface of the metal workpiece, which prevents the formation of a high-quality connection with the solder. Various types of soldering fluxes are used to eliminate such obstacles, some of which also eliminate traces of rust and scale.

Fluxes can be classified just by compatibility with solders (hard and soft) or by temperature resistance. For example, for soft soldering heavy metals use products marked F-SW11 and F-SW32. For solid connection of heavy alloys, soldering fluxes of the F-SH1 and F-SH4 types are used. Light metals like aluminum are recommended to be pre-treated with compounds of groups F-LH1 and F-LH2.

Induction soldering method

This soldering technology has several advantages over the classical hot melt joining method. Among them, one can single out the minimum degree of oxidation of the workpiece, which in some cases eliminates the need to use fluxes, as well as a low warping effect. As for the target materials, they include both soft and hard alloys, as well as ceramics with plastics. For example, the optimal solder for copper in this case will be marked L-SN (modifications SB5 or AG5). As a source of thermal energy during induction exposure, both hand-held lamp devices and machine units of the appropriate power can act. In production, generator sets are also used when it is necessary to obtain a long-term soldering of large-area nodes. Also, a multi-place inductor is included in the work, which can take workpieces in turn. According to this technology, in particular, hand cutting tools are made.

Another modern high-tech soldering method, the development of which was caused by the need to eliminate a number of characteristic shortcomings electrochemical methods connections. Key Feature This technique can be called the possibility of replacing conventional flux as a means of eliminating oxides. The stripping function is performed by the energy of ultrasonic waves, which causes the process of cavitation in the liquid solder. At the same time, the tasks of thermal binding action from the melt are fully preserved.

The superiority of technology in terms of connection speed is also noted. If we compare ultrasonic radiation with the effect that tin-lead solder gives, then the intensity of the collapse of the cavities of the processed node will be several times higher. As observations show, ultrasonic waves with a frequency of 22.8 kHz provide a solder closing speed of 0.2 m/s.

There are also economic benefits this method. They are also associated with a change in approaches to the use of fluxes and solders. In the production of electrical appliances, when assembling monolithic capacitors, current converters and other devices, metallization with palladium, silver and platinum pastes is widely used. The ultrasonic soldering process makes it possible to replace precious metals to cheaper analogues without loss in performance of the future product.

Features of soldering-welding

Soldering as such has many similarities with traditional welding technologies. Also used is the heating of the workpieces and third-party material that affects the formation of the seam. But, compared to welding techniques, brazing does not provide for an internal melt of the workpiece structure. The edges of the parts, as a rule, remain solid, although they are heated. And yet, a complete melt of the workpiece gives a stronger connection. Another thing is that to achieve such a result, more powerful equipment may be required. When using liquid solder for copper, non-capillary soldering with dense filling of the seam is quite feasible. This connection method is partly related to welding, since it increases the adhesion of the structures of two or more workpieces. It is recommended to perform non-capillary soldering with electric arc devices or an oxy-acetylene torch.

Conclusion

Obtaining a high-quality joint in the soldering process is influenced not only by the correct choice of technology, solder with flux and equipment. Often, small organizational procedures associated with the preparation of materials and subsequent processing are of decisive importance. In particular, the use of hard solder requires multi-stage cleaning of the target surface using abrasive grinding and chemical attack with carbon tetrachloride. The finished part should be clean, smooth and as level as possible. Directly during soldering, it is also recommended Special attention pay attention to the method of fixing the workpieces. It is desirable to fix them in a clamping tool, but in such a way that the latter is protected from chemical and thermal effects.

Do not forget about safety precautions. Active consumables - flux and solder - require special care. For the most part, these are chemically unsafe elements that, under high temperature exposure, can release toxic substances. Therefore, at a minimum, one should protect skin and respiratory organs during work.

Soldering methods are classified depending on the heat sources used. The most common soldering in the industry is radiation heating, exoflux, soldering irons, flame, immersion, electric arc, induction, electrical resistance, soldering in furnaces.

Soldering by radiation heating. Soldering is performed by radiation from quartz lamps, a defocused electron beam or a powerful light flux from a quantum generator (laser). The structure to be soldered is placed in a special container in which a vacuum is created. After evacuation, the container is filled with argon and placed in a fixture, on both sides of which quartz lamps are installed for heating. After the heating is completed, the quartz lamps are removed, and the fixture, together with the parts, is cooled. When applying laser heating, concentrated in a narrow beam thermal energy provides evaporation and spraying of the oxide film from the surface of the base metal and solder, which makes it possible to obtain junctions in an air atmosphere without the use of artificial gaseous media. With the radiation method of soldering, radiant energy is converted into thermal energy directly in the material of the solder and the soldered parts. This method of soldering is short.

Exoflux soldering. Basically, corrosion-resistant steels are soldered in this way. A thin powdery layer of flux is applied to the cleaned joint. The surfaces to be joined are aligned, and an exothermic mixture is placed on opposite sides of the workpieces. The mixture consists of different components, which are laid in the form of a paste or briquettes several millimeters thick. The assembled structure is installed in the fixture
and placed in a special furnace in which the exothermic mixture is ignited at 500°C. As a result of the exothermic reactions of the mixture, the temperature on the metal surface rises and the solder melts. This method is used to solder lap joints and ready-made blocks of small structures.

Soldering with soldering irons. The base metal is heated and the solder is melted due to the heat accumulated in the metal mass of the soldering iron, which is heated before soldering or during the process. For low-temperature soldering, soldering irons with periodic heating, continuous heating, ultrasonic and abrasive soldering irons are used. The working part of the soldering iron is made of red copper. A soldering iron with periodic heating during operation is sometimes heated from an external source of heat. Soldering irons with constant heating are made electric. The heating element consists of a nichrome wire wound on a layer of asbestos, mica or on a ceramic bushing mounted on a copper rod of a soldering iron. Soldering irons with periodic and continuous heating are more often used for flux soldering of ferrous and non-ferrous metals with soft solders with a melting point below 300–350°C. Ultrasonic soldering irons are used for flux-free low-temperature soldering in air and for soldering aluminum with fusible solders. Oxide films are destroyed by ultrasonic frequency oscillations. Abrasive soldering irons can solder aluminum alloys without flux. The oxide film is removed as a result of the friction of the soldering iron on the metal.

Importance has an assembly of units for soldering. The assembly must ensure fixation of the relative position of the parts with the required gap and the flow of solder into the gap. In those cases where the solder is pre-laid into the joint in the form of a foil and then the assembly is heated (for example, in a vacuum furnace), it is necessary to ensure that the parts are compressed at the soldering temperature with a certain force. If this force is insufficient, then a too thick seam with unsatisfactory strength will be obtained. Excessive compression can damage the solder assembly.

Special devices are used to compress parts during soldering. The necessary clamping force is provided by mechanical clamps or the difference between thermal expansion product material and fixture material. The latter method is often the only one when oven soldering is carried out at high temperatures.

Gas soldering. When soldering, heating is carried out
the flame of a gas burner. As a combustible gas, mixtures of various gaseous or liquid hydrocarbons (acetylene, methane, kerosene vapor, etc.) and hydrogen are used, which, when burned in a mixture with oxygen, give a high-temperature flame. When soldering large parts, combustible gases and liquids are used in a mixture with oxygen, when soldering small parts - in a mixture with air. Soldering can be done both with special type burners, giving a wide flame, and with normal, welding blowtorches.

Soldering by immersion in molten solder. The molten solder in the bath is covered with a layer of flux. The part prepared for soldering is immersed in molten solder (metal bath), which is also a heat source. For metal baths, copper-zinc and silver solders are usually used.

Soldering by immersion in molten salt. The composition of the bath is selected depending on the soldering temperature, which should correspond to the recommended bath temperature of 700–800°C when working with a mixture of a certain composition. The bath consists of chlorides of sodium, potassium, barium, etc. This method does not require the use of fluxes and a protective atmosphere, since the composition of the bath is selected in such a way that it fully ensures the dissolution of oxides, cleans the soldered surfaces and protects them from oxidation when heated, i.e. . is a flux.

Parts are prepared for soldering, solder is placed on the seam in the right places, after which it is lowered into a bath with molten layers, which are a flux and a heat source, where the solder melts and fills the seam.

Electric arc soldering. In arc soldering, heating is carried out by a direct arc burning between the parts and the electrode, or an indirect arc burning between two carbon electrodes. When using a direct arc, a carbon electrode (carbon arc) is usually used, less often a metal electrode (metal arc), which is the solder rod itself. The carbon arc is directed to the end of the solder rod touching the base metal so as not to melt the edges of the part. A metal arc is used at currents sufficient to melt the solder and very slightly melt the edges of the base metal. Zinc-free high-temperature solders are suitable for direct arc soldering. With the help of an indirect carbon arc, it is possible to carry out the process of soldering with high-temperature solders of all types. For heating in this way, a special coal burner is used. Current is applied to the electrodes
from an arc welding machine.

Induction soldering ( current soldering high frequency ). During induction brazing, parts are heated by eddy currents induced in them. Inductors are made of copper tubes, mostly rectangular or square, depending on the configuration of the parts to be soldered.

In induction brazing, the part is quickly heated to the soldering temperature using high concentration energy. Water cooling is used to protect the inductor from overheating and melting.

Electrical resistance soldering. With this method of soldering, an electric current of low voltage (4–12 V), but of relatively high strength (2000–3000 A) is passed through the electrodes and a short time heat them up high temperature; parts are heated both due to thermal conductivity from heated electrodes, and due to the heat generated by the current when it passes through the parts themselves.

When an electric current is passed, the solder joint is heated to the melting temperature of the solder, and the molten solder fills the seam. Contact soldering is carried out either on special installations that provide power with high current and low voltage, or on conventional resistance welding machines.

Soldering in ovens. For soldering, electric furnaces and less often flame furnaces are used. Heating of parts for soldering is carried out in ordinary, reducing or protective environments. Soldering with high-temperature solders is carried out using fluxes. When brazing in controlled environment furnaces, the cast iron, copper or copper alloy parts to be soldered are assembled into assemblies.

Soldering compounds of metals with non-metallic materials. By soldering, metal compounds can be obtained with glass, quartz, porcelain, ceramics, graphite, semiconductors and other non-metallic materials.

Processing after soldering includes the removal of flux residues. Fluxes, partially remaining after soldering on the product, spoil it appearance, change the electrical conductivity, and some cause corrosion. Therefore, their residues after soldering must be carefully removed. The remains of rosin and alcohol-rosin fluxes usually do not cause corrosion, but if, according to the operating conditions of the products, they are required to be removed, then the product is washed with alcohol, an alcohol-gasoline mixture, and acetone. Aggressive acid fluxes containing hydrochloric acid or its salts are thoroughly washed
successively hot and cold water using hair brushes.

Typical solder joints are shown in fig. 2.1. Soldered seams differ from welded seams in their structural form and method of formation.

The type of solder joint is selected taking into account the operational requirements for the node, and the manufacturability of the node in relation to soldering. The most common type of joint is soldering.

Rice. 2.1. Typical solder joints

In units operating under significant loads, where, in addition to the strength of the seam, tightness is necessary, the parts should only be joined with an overlap. Lap seams provide a strong connection, are easy to perform and do not require fitting operations, as is the case with butt or mustache soldering.

Butt joints are usually used for parts that are irrational to manufacture from a single piece of metal, as well as in cases where it is undesirable to double the thickness of the metal. They can be used for lightly loaded nodes, where it is not required
tightness. The mechanical strength of solder (especially low-temperature solder) is usually lower than the strength of the metal being joined; in order to ensure the equal strength of the soldered product, they resort to increasing the area of ​​​​the solder by means of an oblique cut (in a mustache) or a stepped seam; Often, a combination of a butt joint with an overlap is used for this purpose.

Soldering can be used to produce complex configuration units and entire structures consisting of several parts in one production cycle (heating), which allows us to consider soldering (as opposed to welding) as a group method of joining materials and turns it into a high-performance technological process that can be easily mechanized and automation.

When soldering, the following defects are possible: displacement of soldered elements; shells in the seams; porosity in the brazed seam; flux and slag inclusions; cracks; don't drink; local and general deformities.

Tell me, what is the best method to weld galvanized parts?

Mig-soldering a car element

For joining galvanized surfaces, MIG soldering has recently been recommended instead of semi-automatic welding in argon. During welding, the destroyed zinc coating forms slag, pores, and shells with the molten metal. This means lower quality and no zinc coating in the weld zone. We have to send parts for a second galvanic operation in order to restore anti-corrosion coating, which is not always possible in a node.

Problems when welding galvanized metal

The advent of the MIG soldering method made it possible to avoid such problems. The MIG soldering method differs from the MIG welding method only in the type of wire used and the process mode.

For MIG soldering copper wire CuSi3 is used. The temperature of its solidus is low, which avoids the melting of the base metal. The zinc coating does not evaporate, but when it gets into the bath, it forms a chemical compound close to brass on the surface, which protects the weld from corrosion.

Welding mode for galvanized steels

Soldering is carried out in a protective inert gas environment, and the result is achieved through the selection of the optimal mode of the main and pulsed current, while the transition of the additive into the seam occurs without a short circuit. In the pulsed current mode, its fluctuations from the minimum to the peak value are 0.25 to 25 Hertz. Several times less heat is released on the product, and the spread of thermal influence in the volume of a solid body is sharply limited. The drop breaks away from the filler wire by impulse - as a result, the entire process is practically free from spatter.
In addition to galvanized steels, the process is applied to carbon, low-alloy and corrosion-resistant steels. Brazing is available for vertical seams in any direction (from ceiling to floor and vice versa - no problem) and ceiling. Speed ​​– up to 1000 mm/min.
With the help of MIG-brazing, very thin steel sheets are joined with minimal deformations. The MiG soldering method is used in car service, in shipbuilding, in ventilation and air conditioning systems.
Another option is that bicycle frames are perfectly connected in this way.

Galvanized TIG welding

In TIG welding, if the “as short as possible” arc of the weld is convex, which affects the fatigue strength of the product, high-temperature soldering leads to the appearance of a leader, and MIG soldering compensates for the shortcomings of both the first and second, providing a concave seam and making small the investment of heat in the material, while the strength of the connection remains close to welding.

buy copper wire mm

Appeared long before the invention of electric welding. It was used in ancient Rome and Babylon, as evidenced by archaeological excavations.

During this time, technologies have improved, and new types of soldering have appeared, in which electric current, a gas burner flame, laser energy, or other sources of thermal energy are used to heat the metal.

Capillary type of soldering is the most common. Many, using it, are not even aware of such a name. The essence of the technology is as follows.

The solder is melted, it heats up and fills the space between the two prepared parts. The wetting of the surface of parts and the retention of solder is largely due to the effect of capillarity.

The capillary type of soldering is common in everyday life and in various industries. To carry it out, you will need a soldering iron or a burner. In fact, any type of soldering can be considered capillary to a certain extent, since each type has capillary wetting of workpiece surfaces with liquid solder.

diffusion

This type of soldering differs from the rest in the duration of the process, since diffusion takes time.

The solder inside the weld zone is kept at a certain temperature longer than, say, with conventional capillary soldering. The connection of two workpieces occurs due to the diffusion of solder and soldered metals.

The diffusion process itself consists in the penetration of molecules of one substance into the structure of another substance. Soldering occurs at the molecular level and makes it possible to obtain a stronger seam.

Diffusion type requires strict adherence to temperature and time conditions. The heating temperature in the soldering zone is always higher than the melting temperature of the solder.

Contact-reaction

The type of soldering called "contact-reaction" or "reactive" means the process of fusion when two parts from different metals come into contact.

There is a phase transition of the metal from a solid to a liquid state, followed by hardening and fusion. Often such a connection is carried out through a thin layer, which is applied to one of the blanks by galvanic or other means.

Eutectic materials are used. So you can combine silver and copper, where a copper-silver alloy will be formed between the parts. Conduct soldering of tin and bismuth, silver and beryllium, graphite and steel.

It is possible to solder aluminum with other materials through a layer of copper or silicon. The connection is strong, the soldering time takes a fraction of a second.

Reaction-flux

Reactive flux soldering is based on a chemical reaction in which solder is formed from a flux when combined with a metal. This is clearly seen when aluminum parts are connected to each other.

For their docking, a flux based on zinc chloride is used. When heated, zinc begins to interact with aluminum, turning into a metal solder.

It fills the entire gap space, making the place of the soldering zone a strong connection. In this case, it is very important to accurately observe the proportions of the applied flux. There must be a lot of it so that pure zinc in the required amount can stand out from the flux powder.

Sometimes with this type of soldering, you have to add in small quantities, as an addition to the main process. This is usually done if two workpieces are overlapped.

Soldering-welding

The technology got its name because the process itself is very much like welding metal with filler material (wire or powder).

But in this case, solder is used instead of an additive. This type is most often used to repair defects and flaws on the surfaces of metal parts (cast).

The process itself can be carried out in different ways:

• soldering in furnaces;
• dipping in;
• resistance with electric current;
• induction method;
• radiation;
• using soldering irons and gas burners.

Some species appeared relatively recently, are still being researched and refined.

In furnaces

The first option provides uniform distribution of the solder over the defective parts of the part and uniform heating, which is especially important when you have to solder large-sized workpieces with a complex configuration.

At the same time, heating in the furnace can take place by one of the many existing methods, ranging from flame heating to complex technological processes, such as induction, electrical resistance.

The design of the furnaces themselves differs from each other only in the hearths on which the soldered workpieces are placed. For large parts, furnaces are used in which the hearth does not move, and for small parts, they are movable in the form of conveyors on rollers.

The main task of this type of soldering is to create a special gaseous substance inside the furnace. Soldering in furnaces can be completely mechanized, which leads to increased productivity. And for productions with mass output finished products this is the ideal option.

Application of induction and resistance

As for the induction type, high frequency currents are used for it. Electricity is passed through the soldered parts, which is why they heat up.

Two soldering methods are implemented here: stationary and with the movement of a part or an inductor. In the case of joining large-sized workpieces, the second technology is used.

The resistance soldering method is somewhat similar to the induction type. It's just that in this technology, the current is passed through both the workpieces and the soldering element. That is, the connected parts become part of the electrical circuit.

Such a process is carried out in electrolytes or in special contact machines, the operation of which is very similar to standard electric welding. Contact machines are usually used in industries where it is necessary to solder together thin sheet metal products.

Soldering in electrolytes is not often used today due to the complexity of setting the parameters of the technological process. After all, the process takes place according to the principle of the thermal effect that occurs between the cathode (soldered parts) and the anode.

A hydrogen shell is formed around the blanks, which has a very high electrical resistance. Hence the release of large thermal energy.

bath immersion

Soldering with immersion is carried out either in a medium of molten solder or in a mass of special salts. The last type of soldering is a fast operation due to the direct heating of the workpieces from salts, which act as both a heating element and a flux. With regard to immersion in solder, the possibility of full or partial immersion should be noted.

radiation method

The radiation type of soldering is produced due to a powerful light flux, which is formed by a quartz lamp, a laser or a defocused cathode beam.

The technology appeared relatively recently, but showed that in this way it is possible to achieve high quality soldering of two metal blanks. In addition, there was a real opportunity to control the process both in terms of the degree of heating and in terms of time. At the same time, the laser removes the oxide film from the solder and from the metal, which guarantees high quality solder seam.

The gas shell in the connection zone, formed by heating the metals, makes it possible not to use fluxes when connecting. Therefore, when people talk about flux-free soldering today, they mean laser technology.

Torch and soldering iron

As for soldering with torches, two technologies are most often used, which, in fact, are no different from one another. There is simply a heating of the two parts and the solder placed between them in the gap.

In the first method - due to the combustion of gas, in the second - due to the formation of plasma (this is a combustible gas that moves in a thin jet at high speed). It should be noted that the method with gas burners is considered universal.

Torches that emit a plasma stream operate at high temperatures. And this allows you to solder together parts made of titanium, molybdenum, tungsten and other refractory materials.

The complexity of this technology lies in the fact that it is almost impossible to adjust the electric arc to a certain heating temperature (to a certain accuracy).

Soldering with a soldering iron has been used for a long time. If 5-10 years ago it was possible to talk only about electrical appliances or those heated by fire, today there are much more proposals.

I would like to note soldering irons powered by ultrasound. That is, ultrasound itself is related to the soldering process only from the standpoint of the destruction of the oxide film.

Therefore, it became possible to solder various metals in an air environment without flux materials. Direct soldering comes from heating the solder.

Vacuum

Vacuum soldering is still not always and everywhere used today. The complexity of this type lies in the fact that it is necessary to create a rarefied atmosphere without air in the soldering zone.

As you know, the oxygen present in the air is the cause of the formation of an oxide film, which covers metal workpieces and solder.

The film is very refractory; when soldering, temperature degrees are lost to heat the parts to be joined. Therefore, all scientists are still looking for ways to remove the oxide coating or carry out the process without it. Vacuum soldering is one such option.

The following factors prevent the introduction of a vacuum type into production:

• low productivity of the process, because each individual part has to be heated;
• in this way, only workpieces of small sizes can be soldered;
• the complexity of creating machines and additional equipment;
• the complexity of the soldering process.

However, if we talk about space, where there is no atmosphere, then the vacuum view is considered very promising.

Selective

It cannot be said that the selective type of soldering is fundamentally different from the capillary one. In the same way, solder and heat are used in it. But the solder is melted only in selective places (local points) on which it is planned to attach the elements.

Selective soldering is used mainly for the manufacture of boards and pins of pin components. It is similar to the wave method used for soldering smd chips.

The selective soldering unit is equipment belonging to the category of semi-automatic devices. It is not cheap, but it saves consumables by almost ten times compared to the wave, so it spreads wider and wider.

Temperature regime and materials

The classification of soldering processes is based on the methods of operation, the conditions under which the joints are obtained, and on the types Supplies. The concepts and types of soldering are described in detail by GOST 17325.

Soldering is called high-temperature or hard soldering if the solder is heated to a temperature of 450 ℃ and above. Otherwise, you have to deal with a low-temperature type (soft).

For low-temperature type, low-melting solders are used. These include alloys of tin and lead, bismuth, gallium, and indium. To refractory belong copper-silver, copper-zinc solders.

Due to the dictates of new materials and environmental safety requirements, soldering technologies are constantly changing. Lead solders are being used less and less, smoke detectors are being installed, and laser and ultrasonic equipment are being developed.

A significant role in the development of soldering is played by the introduction of robotic systems, which can significantly speed up work.