Why you can’t solder copper parts with steel solder

Copper pipe soldering technology

Entire plumbing or heating systems made of copper are rarely made today, but they are still done. If you calculate the number of years during which copper can last, it turns out that it is not only inexpensive, but very cheap. However, the material itself is not the cheapest, but you can save on installation - soldering copper pipes is not the most difficult task in the world. There are certain rules and features, knowing which you can achieve a quality connection.

Types of copper pipes and their uses

There are two types of copper pipes on the market: annealed and non-annealed. After formation, annealed ones undergo additional heat treatment - they are heated to 600-700°C. This procedure returns elasticity to the material, which is lost during molding. Therefore, annealed pipes are more expensive, but also more flexible - they can even withstand freezing of water. The disadvantages of these products include lower strength - it decreases due to heating.

There are different types of copper pipes

Unannealed copper pipes are stronger, but practically do not bend. When installing plumbing or heating, they are cut into pieces, and all bends are made using appropriate fittings.

There are copper pipes with different wall thicknesses, sold annealed in coils of 25 and 50 meters, unannealed in runs of 3 meters. If we talk about the purity of the material, then according to GOST 859-2001, at least 99% copper must be present in products.

Connection methods

Most often, copper pipes are connected using soldering and a set of special shaped elements - fittings. There are also fittings for crimping. They have grooves with a rubber O-ring installed. They are crimped with special pliers. But this technology is used infrequently - soldering is considered more reliable.

Fittings for crimping

There are two technologies for soldering copper pipes using different solders:

• Low temperature - with soft solder. This is exactly our case. This type of connection is used when laying water pipes and heating systems with a working environment temperature of up to 110°C. Low temperature is a relative concept. In the soldering zone, materials are heated to 250-300°C.
• High temperature brazing. This type of connection is used in networks with high pressure and temperature of the transported medium. In household networks - rarely (although no one prohibits), more often in industrial ones.

What type of copper pipe soldering you use is your choice. Both types are suitable for both plumbing and heating. But high-temperature solder requires a professional torch, while soft solder can be melted even with a blowtorch or an inexpensive hand torch with a small disposable gas cylinder. To connect small-diameter copper pipes, no more is required.

Types of Copper Solder Fittings

In general, there are more than two dozen different shaped elements for copper pipes - fittings, but three types are most often used:

• couplings - for connecting two pipes;
• corners - for turning;
• tees - for creating branches in the pipeline.

Couplings for soldering copper pipes

The number of fittings used can be minimized - copper can be bent, which will reduce the number of angles needed. Also, if desired, you can do without couplings: one end of the pipes can be expanded (using an expander) so that the pipe goes into it and there is a gap for solder to get there (about 0.2 mm). When creating an expansion, the pipes must overlap by at least 5 mm, but more is better.

What’s hard to do without is tees. There is equipment for inserting a branch - a beading machine, but it is professional and costs a lot. So in this case it’s cheaper and easier to get by with tees.

There are fittings for soldering copper pipes with soldered solder

There are two types of fittings - conventional, with sockets, which provide the required clearance for solder to flow. Solder is supplied to the welding zone manually. There are fittings with built-in solder. Then a groove is formed on the socket, into which, during production, a piece of solder is installed, which makes the soldering process easier - you just need to heat the welding zone, but leads to an increase in the cost of fittings.

Consumables and tools

In addition to pipes and fittings, you will also need a torch, solder and flux for the soldering itself. And also a pipe bender and a few related little things to process before starting work.

Brush for cleaning fittings from the inside

Solder and flux

Soldering of copper pipes of any type occurs using flux and solder. Solder is an alloy usually based on tin with a certain melting point, but always lower than that of copper. It is fed into the soldering zone, heated to a liquid state and flows into the joint. After cooling, it provides a tight and durable connection.

For amateur soldering of copper pipes with your own hands, tin-based solders with the addition of silver, bismuth, antimony, and copper are suitable. Compositions with the addition of silver are considered the best, but they are the most expensive; the optimal ones are those with a copper additive. There are also ones with added lead, but they should not be used for plumbing. All these types of solder provide good seam quality and easy soldering.

Flux and solder - necessary consumables

Soft solder is sold in small spools, hard solder is sold in packs, cut into pieces.

Before soldering, the joint is treated with flux. Flux is a liquid or paste that allows molten solder to flow into a joint. There is nothing special to choose here: any flux for copper will do. Also, to apply the flux you will need a small brush. Better - with natural bristles.

To work with soft solder, you can buy a small hand torch with a disposable gas cylinder. These cylinders are attached to the handle and have a volume of 200 ml. Despite its miniature size, the flame temperature is 1100°C and higher, which is more than enough to melt soft solder.

What you should pay attention to is the presence of piezo ignition. This function is not superfluous - it will be easier to work with. There is a valve on the handle of the manual gas burner. It regulates the flame length (gas supply intensity). The same valve shuts off the gas if the burner needs to be extinguished. Safety is ensured by a non-return valve, which will shut off the gas supply if there is no flame.

Hand torch for soldering copper pipes

Some models have a flame deflector installed. It prevents the flame from dissipating, creating a higher temperature in the soldering area. Thanks to this, the burner with a reflector allows you to work in the most inconvenient places.

When working with household and semi-professional models, you must be careful not to overheat the unit so that the plastic does not melt. Therefore, it is not worth doing a lot of soldering at one time - it is better to let the equipment cool down and prepare the next connection at this time.

Related materials

To cut copper pipes, you need a pipe cutter or a hacksaw with a metal blade. The cut must be strictly vertical, which is ensured by a pipe cutter. And to ensure an even cut with a hacksaw, you can use a regular carpenter’s miter box.

When preparing pipes, they must be cleaned. There are special metal brushes and brushes for this (for cleaning the inner surface), but you can get by with sandpaper with medium and fine grain.

To remove burrs from cuts, there are chamfer removers. The pipe they used fits better into the fitting - its socket is only a fraction of a millimeter larger than the outer diameter. So the slightest deviations lead to difficulties. But, in principle, everything can be removed with sandpaper. It will just take more time.

It is also advisable to have safety glasses and gloves. Most home craftsmen neglect these safety measures, but burns are very unpleasant. These are all the materials and tools needed to solder copper pipes.

Step-by-step copper soldering technology

Soldering copper pipes begins with preparing the connection. The reliability of the connection depends on the quality of preparation, so devote enough time and effort to this process.

Soldering copper pipes consists of several stages

Preparing the connection

As has already been said, the cut of the pipe must be strictly vertical, without burrs, the pipe must not be wrinkled, the edge must be even and smooth. If there are even slight deviations, we take a bevel remover or sandpaper and bring the cut to perfection.

It is necessary to remove the oxidized layer

Next, take the fitting and insert the pipe into it. the part that goes into the socket requires cleaning. We take out the pipe and use sandpaper to remove the top oxidized layer from this part of the pipe. Then we carry out the same operation with the inner surface of the bell.

Flux application

Flux is applied to the entire cleaned surface - outside the pipe and inside the fitting. There are no difficulties here - the composition is evenly distributed with a brush.

The treated pipeline fragments are inserted into one another and fixed. If there is an assistant, he can hold the parts motionless. If not, you'll have to figure it out yourself. Next, the burner is ignited and the flame is directed to the connection point. The flame temperature is from a thousand degrees and above, and the joint must be heated to 250-300°C, and this takes 15-25 seconds. In this case, you can focus on the color of the flux - as soon as it darkens, it’s time to introduce solder.

Correct position of the torch when soldering copper pipes with your own hands

To ensure uniform heating, direct the burner flame in the middle of the joint. Then the entire welding zone heats up more evenly.

Soldering copper pipes with soft solder

Solder is injected into the joint - where the fitting and pipe connect. As it heats up, it begins to melt, spreads and fills the gap between the elements. You can only apply it to half the length - once it melts, it will flow into the rest of the joint. Actually, that's all - the soldering of the copper pipes is finished. All other connections are made the same way.

When using hard solder, everything is almost the same, only other burners are used - gas-flame ones, and during the soldering process you need to turn the pipe, winding the softened solder onto the pipe.

Source: https://otoplenie-doma54.ru/stroitelstvo/pajka-mednyh-trub-tehnologiya-oborudovanie-osobennosti.html

How to solder copper and steel

Soldering brass, which allows you to obtain high-quality and reliable connections, is a technological process that involves the use of a gas torch, as well as special solder.

The latter is wire, the material of which can be tin or an alloy of this metal with lead.

If you thoroughly study the features of such a process, as well as prepare all the necessary equipment and consumables, then you can successfully perform it even at home.

Brazing process for brass parts

Conditions and scope of soldering

Before understanding the question of how to solder brass, you should thoroughly study all the features of such a technological process. When performing soldering, which is one of the methods for producing permanent connections, molten solder is introduced into the gap located between the parts being connected, which acts as a fastening element.

An important condition for soldering is that the solder, which is melted using a gas burner, must melt at a lower temperature than the material used to make the parts being joined. This technology (in some cases it is the only possible way to obtain a permanent connection) allows even dissimilar metals to be reliably soldered together.

Brass soldering diagram using a gas torch

It is completely wrong to compare soldering with a technological process such as welding, which assumes that not only the special solder wire will melt, but also the metal of the parts being connected.

It is precisely due to the fact that when performing soldering, the solder is exposed to the main temperature effect, the characteristics of the parts being connected and their integrity remain unchanged.

This feature allows this technique to be successfully used for joining metal parts that are even very small in size.

Meanwhile, it should be borne in mind that for soldering, softer materials are used as solder when compared with those used to form the weld. This leads to the fact that connections created by soldering are initially less strong and reliable than welded seams.

And in cases where brass is soldered, zinc evaporates from the solder during intense heating, which leads to porosity of the formed seam. Such metal porosity significantly impairs the quality and reliability of the connection. When soldering parts made of brass, their relative position is also of great importance.

It is better to connect such parts not end-to-end, but overlapping.

For soldering at home, you can get by with a manual gas torch with a 1.8 kW cylinder

Metal soldering as a technology that makes it possible to obtain permanent connections occupies one of the leading positions, second only to welding in popularity.

This technology is practically indispensable in the electronics industry, where it is used to create electrically conductive connections between elements of various instruments and devices.

It is with the help of soldering that wires are most often connected and extended, through which electric current will subsequently pass.

If we talk about the most common areas of application of soldering, then these include:

• formation of hermetic connections of pipes made of copper and its alloys, including brass (such pipes are used primarily for completing refrigeration and heat exchange units);
• fastening carbide inserts to the bearing part of the cutting tool;
• connection between parts that differ significantly in thickness.

The photo shows the result of soldering a brass tube and a jet. We used P14 fluxed solder and an imported pure propane burner.

Using soldering equipment and solder, they also perform a technological operation such as tinning, which allows you to create a reliable anti-corrosion coating on metal surfaces.

Depending on the type of solder used for soldering, it can be high or low temperature. The use of a more refractory material when soldering allows you to create connections that can be operated at higher temperatures.

The use of such an alloy, in particular, is quite problematic at home, where a conventional blowtorch is most often used for soldering.

Features of the technology

Both in industrial and at home conditions, one has to face the need to connect products made of brass by soldering. This is due to the fact that this alloy of copper and zinc is actively used for the production of elements of plumbing and heating systems, as well as many other products.

The correct choice of flux is of great importance for obtaining a high-quality and reliable connection of brass products using soldering. To successfully carry out this process, ordinary flux, which contains alcohol and rosin, is not suitable.

Due to the rather low activity of its constituent components, such a flux is not capable of dissolving the oxide film that is necessarily present on the surface of a brass product.

That is why for soldering brass products it is necessary to use a more active flux, which is often used as zinc chloride.

Composition and use of acidic active pluses

Quite popular fluxes that are used for soldering brass in salt baths are borax and potassium fluoroborate. Such fluxes, the amount of which in the bath solution, as a rule, does not exceed 5%, ensure good flow of molten solder into the gap between the parts being connected.

The correct choice of solder wire is another important task that must be solved in order to obtain a high-quality connection of brass parts.

For soldering brass products that will later be used in a gas environment, you can use popular types of solders based on silver and phosphorus copper alloys.

Such solders are also ideal for joining brass products containing a significant amount of copper.

Brands and applications of solders

Brass itself is often used as solder, but it is necessary to ensure that the melting temperature of the filler wire does not exceed the same parameter of the parts being connected. In cases where it is necessary to form a connection of increased reliability using soldering, hard solders are used, which, when compared with soft-type filler materials, have higher strength.

Particular attention should be paid to the selection of solder and the soldering technology itself in cases where dissimilar materials need to be soldered together.

It should be taken into account that such materials have different melting points and can also behave completely differently when heated.

In particular, when intensely heated, zinc begins to evaporate from brass, which negatively affects both the decorative and strength characteristics of the joint being formed (it acquires a porous structure).

You can use a bucket of small pebbles as a fireproof substrate.

Certain technological methods allow one to avoid active evaporation of zinc from brass that is heated during soldering.

The most effective of these techniques is the use of flux, which will perform a protective function, preventing the evaporation of zinc from the brass structure.

The use of combined solder for soldering, which includes not only filler material, but also flux, is another effective way to avoid the evaporation of zinc from brass.

By choosing the right solder and soldering technology, you can even connect parts made of such a complex material as stainless steel at home. It should be borne in mind that brass solder is not suitable for soldering stainless steel parts; completely different materials are intended for this.

Brief instructions

In order to perform high-quality brass soldering at home, it is not enough to simply study the theoretical basis; it is also advisable to watch a video on this topic.

The need to independently carry out such a process often arises, because almost every home has brass products that are not insured against breakdowns.

  The influence of copper on the properties of steel

Considering the fact that the services of qualified specialists are not cheap, it makes sense to study this process using both the recommendations presented below and videos that are easy to find on the Internet.

Of course, parts should be cleaned before soldering.

So, the algorithm for soldering brass is as follows.

• A thoroughly cleaned area of ​​the future connection must be treated with a flux containing borax and boric acid (1:1) mixed with water.
• After this, the treated joint should be sprinkled with solder shavings.
• Then you can begin heating the seam being formed using a gas burner or blowtorch. Care should be taken not to overheat the parts, which could lead to their deformation.
• After the solder melts under the influence of the flame of a gas burner, it will fill the gap between the parts, ensuring their reliable connection.

Thus, soldering brass is not so difficult; the main thing is to choose the right consumables and strictly follow the above recommendations.

Source: https://steelfactoryrus.com/kak-spayat-med-i-stal/

How to solder copper to brass - Metals, equipment, instructions

Taps, hardware, pipes, decorative interior items and many other products are made from brass. This material is obtained by fusing copper, zinc (in different proportions) and various additives.

Soldering brass ensures a reliable and high-quality connection of parts. Soldering involves the use of a special tool in the form of a gas torch, as well as solder made from a mixture of tin and lead. In some cases, tin alone is used to make brass solder.

Advantages and disadvantages

If you have the necessary tools and materials, and after learning the basic techniques for handling brass, you can solder this material yourself.

Soldering brass products has several features. This technology involves the use of specially prepared solder, which is introduced into the gap between the parts and plays the role of a “grasping” element. In addition, the equipment through which the solder material is melted is essential.

Typically, a gas torch is used for soldering, which ensures that the solder wire melts at temperatures lower than the melting point of the brass itself. Using this technology, it is possible to reliably solder individual workpieces of similar or dissimilar materials in structure.

In some cases, the use of brass soldering is the only possible way to obtain permanent contacts.

It is unacceptable to compare soldering with welding procedures in which each of the metals being fused is subject to melting. In this case, only hard solder with tin is exposed to thermal effects, and the condition of the parts being connected remains unchanged.

This feature allows you to process brass products of very small size and weight without causing any damage to them.

When carrying out soldering, it must be taken into account that this process involves the use of softer consumables than when welding. As a result, the joints obtained by soldering are considered less strong compared to welded seams.

In cases of working with brass, zinc completely evaporates from the solder body (due to its strong heating), as a result of which the seam becomes porous, which significantly reduces the quality of the joint formed.

In addition, when soldering brass parts, it is important to correctly select their relative position (in this case, preference is given to “overlapping” joints).

Application

Modern technologies for processing copper and zinc alloys are widely in demand in such industries as:

• electronics and electrical engineering;
• instrument making and tool production;
• production of refrigeration and ventilation equipment.

If you have everything you need (solder of the required quality, flux and soldering torch), you can tin the brass surfaces in order to protect them from corrosive destruction. The tinning procedure is also in demand when repairing heating and plumbing systems made on a brass basis.

Depending on the type of solder used for soldering, connections are divided into high- and low-temperature. This division allows the use of more refractory joints for soldering workpieces operated at high temperatures.

Using high-temperature soldering is impossible at home, since this situation requires special equipment.

Features of soldering homogeneous workpieces

In everyday life, there is often a need to solder two brass blanks that are identical in structure. In this case, the correct choice of flux composition, which differs from the traditional combination of rosin and alcohol, becomes of paramount importance.

Due to the low activity of the components, a conventional composition will not be able to dissolve the oxide film that forms on the surface of brass. So for the soldering option under consideration, a more active flux based on chlorine and zinc will be required.

All the details of its preparation can be found in the table, which shows several types of zinc chloride mixtures.

In addition to the types of flux considered, when soldering brass, compositions based on borax and potassium fluoride-boron salt can be used. Mixtures prepared from them occupy no more than 5% of the total volume of the solder bath and have excellent activity indicators.

Activity refers to the ability to create ideal conditions for the penetration of molten solder into the gaps between parts during soldering.

Along with the problem considered, we should not forget about a competent approach to the selection of solder supplied to the joint in the form of calibrated wire of one composition or another.

In the case where soldered brass products are intended to be used in a gas environment, it is advisable to use special types of solders made on the basis of copper phosphate and silver alloys. They are also suitable for soldering red brass with a high percentage of copper content.

Sometimes wire made from brass itself is used as solder. However, in this case, it is possible to solder a brass part only if the melting point of the brass wire is lower than the same indicator for the workpieces being processed.

General procedure

Before you start soldering brass parts yourself, you should thoroughly clean them of foreign deposits and contaminants. Next, you need to place them on a fire-resistant substrate, the function of which can be performed by river pebbles poured into an old bucket.

The general procedure for soldering brass can be represented as follows.

• first, the place of the intended connection of two parts is treated with a flux of suitable composition, after which finely planed crumbs of solder material are poured onto it;
• after this, you can start heating the brass (only at the joint!) using a previously prepared burner;
• After melting the solder material and filling the gaps between the parts with liquid composition, turn off the burner and wait for the joint to cool down.

During the soldering process, overheating of the workpieces is unacceptable, which can cause their deformation. In general, independent brass soldering is not something completely inaccessible.

To master this technology, it is enough to correctly select all the necessary consumables and strictly follow the recommendations given.

Source: https://spb-metalloobrabotka.com/kak-pripayat-med-k-latuni/

How to solder copper with hard and soft solder

Copper products are found everywhere in different areas of life. For example, it is used to create strong and durable heating and water supply systems. But to connect the two elements, experts resort to a special technology - soldering copper pipes. The procedure requires suitable tools and materials, as well as knowledge. Since it has certain features that a beginner may not know about.

To solder copper, the master needs to have with him a composition such as solder. This thermoplastic substance seals the surface of the product and, under the influence of high temperature, melts, spreading over the entire joint. But as soon as it cools, it hardens and securely holds the products together.

The result is one item that has a long service life, withstands high loads, pressure and temperature changes, and is not afraid of ultraviolet radiation.

What tools and materials are needed

Soldering is carried out not only at industrial facilities, but also at home. To do this, you need to prepare the following tools and materials:

• electric soldering iron or gas burner;
• pipe cutter;
• solder;
• flux;
• brush and steel brush.

How exactly to connect the products depends on the convenience and preference of the master. But the power of the device is selected in accordance with the melting temperature of the solder.

Flux can be liquid or solid; each type has individual differences that should be taken into account. If the material is used in the form of a thickened mixture, then it is applied to the joint, both before and after the connection.

Flux is needed to protect the surface from oxidation, promote solder flow and improve adhesion.

Types of fluxes and solders, features of working with them

Craftsmen know a variety of hard and soft substances that ensure high-quality soldering of metal products. 95% use tin, which is a low-temperature composition with slightly worse technical parameters. But it is valued for the fact that work can be carried out at any temperature without reducing the strength of the products being joined.

Connecting elements also include silver, which has excellent technological properties. Craftsmen often use three-component compositions of silver, tin and copper. Often, materials used in low-temperature soldering contain zinc chloride.

The advantage of soft solders is that they cover a larger area when applied to the surface of the part. They provide high strength and reliability.

Soft solders

Soft solder is used in the installation of water supply and heating networks, where the pipe diameter reaches 10 cm and the water temperature does not exceed 130 degrees. These types include:

• lead-tin type;
• with low tin content;
• special and fusible.

Lead-free flux is most often chosen as solder. The tin-copper type is the most common due to its affordable price. But its advantage lies elsewhere. All mixtures containing tin in the composition are economical in consumption.

It is enough to apply a little solder to half the surface being treated and it will spread over the entire area. This property is explained by the fact that tin easily penetrates and spreads throughout any structure.

Brazing alloys

When it comes to considering the environmental conditions in which soldering is performed, it is better to use hard solders. The use of such substances ensures high strength of the seam. The most common compounds are the following compounds:

• copper and zinc;
• phosphorus and copper;
• pure copper;
• no-clean flux.

Solid compounds are classified as refractory and low-melting. Each type is characterized by certain properties. For example, copper-phosphorus replaces expensive silver flux. It is moderately expensive, but has one drawback - it cannot be used at low temperatures.

The strongest of the solid compounds are copper-zinc and multicomponent ones. They are expensive, but the price is justified by the reliability of the connection. When soldering is performed with copper itself, it is necessary to use flux. In this case, it will be possible to firmly connect the two parts.

Why do you need solder paste?

Solder paste is a pasty mass consisting of small particles of solder, flux and special additives. Flux paste is used in industry when soldering elements on printed circuit boards. The paste is selected according to certain conditions:

• after application there should be easily removable particles;
• the substance must maintain viscosity and stickiness;
• do not have a negative impact on the surface being treated;
• do not leak onto clothing during melting.

How to work with the paste depends on the type and size of solder contained in its composition. The material also differs in the type of flux (rosin, water-washable, no-clean). It is necessary to hold small parts in place and facilitate the joining process.

Soldering technology

The process is quite simple, therefore, when it is necessary to connect something at home, the owner does the soldering with his own hands and without the involvement of specialists. But still, you can’t do without the preparatory stage.

It determines how high-quality and reliable the connection will be. First of all, you should pay attention to the cut of the part, which should be strictly vertical, without burrs, with even and smooth edges. If you find the slightest defects, you should take sandpaper and rub it over the surface until the defects disappear.

If two copper pipes are connected, then, having brought the cut to an ideal state, it is necessary to insert it into the fitting and then remove it. The part that came into contact with the fitting must be cleaned of oxidation. The next step is applying flux. There is nothing complicated about this, you just need to run the brush over the entire part, paying special attention to the joint.

Then the elements are connected to each other and firmly fixed. Further actions depend on what is being used for soldering - a gas torch or a soldering iron. Considering that the parts must be stationary, an assistant will be required. He will be the one to hold them, but if one is not found, you need to manage and do it yourself.

When something needs to be soldered at home, a solid compound is most often used. But the master can purchase special pastes. With the correct choice of compositions, it is possible to connect two pipelines or radio components as accurately and firmly as possible.

Soldering is performed at either high or low temperature. In the first case, the process is distinguished by high strength of the seam, and the connected area also gains heat resistance. Which is very important if it later serves as part of various communications. But high-temperature soldering is not allowed on threaded connections. Most often this process is performed with a propane-filled torch.

When low-temperature soldering is used, a soft compound, paste or gel is used. It is most suitable for a beginner master because it is simple and easy. In this type of process, the temperature does not rise above 425 degrees, so it is even possible to use a soldering iron, which is found in almost every home.

Working with a soldering iron

Every person has seen a soldering iron at least once in their life, and many constantly work with it. Therefore, they will not see anything complicated in soldering copper products with this tool. The whole essence of the process is that the solder located between the two parts is heated with a soldering iron until it begins to melt.

When it hardens, the two parts will be securely fastened into one. To solder efficiently, it is necessary to distribute the substance evenly over the entire surface, filling every gap. It is important to choose exactly the material that can withstand the high temperature of the soldering iron.

Working with the burner

The tool is turned on when the two parts are already connected to each other. You should not hold it near the joint for too long, since the combustion temperature is several thousand degrees. While you only need to heat a certain place to 250-300 degrees.

This will take 20-30 seconds. As soon as the flux changes color to dark, the compound to be joined is introduced. Important! The burner or hair dryer should be placed in the middle to cover the entire joint area.

Is it possible to solder copper with tin?

Many novice craftsmen are interested in whether it is possible to solder copper with tin. In fact, it’s not just possible, but necessary. Because this composition provides good bonding. Most often, tin is used when holding food items together.

There is only one thing to remember - this metal requires a higher temperature than other solders. It is better to use a powerful electric soldering iron as a tool.

Soldering with silver solder

When you need to solder parts at home, silver solder is often used. It is beneficial because you can create it yourself. But it should not be used alone, in combination with zinc and copper.

Treated with this solder, the seam will be very strong and neat. The percentage of components is controlled by GOST 19746 74. But you can find out exactly what types of substances to use from the instructions of experienced craftsmen or those included with the products being connected.

How to solder copper and stainless steel

If you need to solder copper to another metal, such as steel, you will have to work hard. This process is not easy, but it is quite feasible. This is explained by the fact that stainless steel interacts poorly with other metals and is difficult to heat treat.

When two different products are combined, you need to find an average composition that suits both at the same time. In such cases, you have to sacrifice quality and it is not even necessary to use flux. But it is important to carry out preparation, tinning and other soldering steps.

The need for a connection often arises at home. Joining stainless steel and copper requires little time and a conventional gas torch is sufficient. Therefore, having decided on the tool and solder, you should clean the surface of both joints and prepare flux. Then tinning the bonding area and applying flux. After which the two parts are connected, and the resulting seam is coated with solder.

The next stage is its uniform heating with a burner. Once the solder has spread, the product is left to cool naturally.

How to solder copper to iron

Soldering copper products to iron ones or vice versa is also a common task, for which the connecting compound is selected correctly. The instructions in this matter will be of significant help.

Useful information can be found in the thematic video, where the entire soldering process is shown in detail. If all conditions are met, it is possible to obtain an even and durable seam.

Basic mistakes when soldering yourself

Most often, it is haste that leads to the fact that the connection of two elements is unsuccessful. Because they forget to inspect the surface of the parts being connected. The first action aimed at correcting an error is checking for the absence of defects. They could appear when cutting parts.

How reliable the seam will be depends on the cleanliness of the surface. Therefore, it is still worth brushing off even invisible specks of dust. One of the most basic mistakes is made when applying flux. The master may forget to process a small area of ​​the product. And it will cause the proper connection to fail.

It is also important to monitor the temperature of the torch or soldering iron, since overheating of the element being processed leads to combustion of the flux. But insufficient melting point is also harmful. In this case, the connecting compounds do not soften or stick.

Safety precautions

Soldering copper products is a rather dangerous process, so it is very important to comply with all standards and regulations for safety. The process involves open flames and hazardous substances, so DIYers and professionals alike must wear protective equipment. We are talking about mittens, glasses and special clothing.

Before you take up the tool, you need to carefully study the rules of technology.

Source: https://oxmetall.ru/pajka/medi-tverdym-i-myagkim-pripoem

How to solder steel at home?

> Electrician's tips > How to properly solder with a soldering iron with acid

Most often, for soldering printed circuit boards in radio engineering products and household appliances, they prefer to use ordinary pine resin rosin, but it can be replaced with other components. When molten, it promotes the spreading of tin solder along the copper traces of the board.

This allows you to reliably solder the legs of radio components and the ends of connecting wires. Rosin allows you to effectively solder copper, tin and silver products.

In order to solder galvanized and stainless iron, radiators, buckets, pans, various alloys, brass and other metals, you can use acid solutions.

Bottle with acid solution for soldering metals

Acidic solutions

It is important to choose the right acid solution. It depends on the type of metal from which the parts are made. This could be an aluminum or copper radiator, a kettle that needs to be soldered, copper, brass or roofing iron:

1. Galvanized iron. Places where it is necessary to solder are treated with an acid solution, correctly called (zinc chlorate). This composition can be bought in specialized stores; the easiest way is to prepare it yourself.

To do this, it is enough to throw pieces of zinc into 100 ml of hydrochloric acid, which can be removed from the body of AA batteries. After the chemical reaction is completed, the zinc will dissolve, releasing a large amount of hydrogen.

It is correct to carry out the process in a well-ventilated area, in the absence of open flame.

After the solution has cooled and settled, the upper transparent yellow part is poured into a clean glass container. The sediment is poured into the ground; it is not recommended to drain into sewers with metal pipes. Acid can damage pipes and seals. The remaining part of the solution is ready for processing galvanized iron roofing.

How to solder sheets of roofing iron

1. Stainless steel. Before soldering, the surface is cleaned and treated with phosphoric acid, which contains the following elements:
   

• up to 50% zinc chloride;
• ammonia up to 0.5%;
• dissolves in water with a pH concentration of 2.9%.

Phosphoric acid is used for soldering as a flux and for cleaning metal from rust.

The solution can be transparent, light yellow or colorless; when heated to 213ºC, it is converted into H4P2O7 (pyrophosphoric acid), which degreases the surface of metals. The composition dissolves the oxide film on various metals and alloys:

• stainless steel;
• brass;
• Nickel alloys;
• copper alloys;
• alloys of carbon metals and low-alloy steel.

Application of acids

To solder metal products (pipes, radiators, buckets, pans), the surface of the elements is thoroughly cleaned, using a file or sandpaper. An acid solution is applied to the cleaned areas with a brush, after which solder is melted to a liquid state on the surface with a soldering iron.

How to solder correctly with a soldering iron

Liquid solder tins the cleaned areas; when boiling, the acid flux comes to the surface. When the solder hardens, the soldered elements are securely and hermetically fixed.

You can solder with a powerful soldering iron or an open flame from a gas burner. Various heat sources can be used depending on the surface area to be heated and the melting point of the solder.

Remains of acid flux are washed off with water, preferably a soapy, alkaline solution, this will prevent further corrosion of the metal.

Machined and brazed stainless steel elements

Acid can damage skin and muscle tissue, and inhaling vapors can damage the respiratory organs. When contacting air, hydrochloric acid enters into a chemical reaction, and smoke is visible above the open container. To work correctly in these conditions, wear safety glasses, rubber gloves, a gas mask, or a respirator.

If the solution gets on the skin, wash this area of ​​the body with a 6% alkaline solution or plain soap. It is not recommended to solder radio circuit boards with fluxes containing acid. The acidic components are difficult to wash off and contribute to the breakdown of copper tracks. It is better to replace them; there is a special paste for this.

Soldering acid solutions should be stored correctly in containers made of the following materials:

• glass;
• ceramics;
• porcelain;
• fluoroplastic

Such dishes do not react with acid; the prepared composition can be stored in it for a long time.

Soldering without a soldering iron

At home, if you don’t have a soldering iron, you can solder copper wires with a diameter of up to 2 mm. For soldering radiators and utensils, special solder, blowtorches, and gas torches are used, since the copper rod of the soldering iron is not able to heat a large surface area. There are several ways:

1. Tinning and soldering wires in molten solder . The wire is first heated, applied to a piece of rosin, it melts and spreads evenly over the surface of the connection. The wire is twisted and lowered into molten solder in a tin can over a fire; it can be heated with a blowtorch. In order to solder the twist, it is advisable to hold it in boiling tin for up to 1 minute. The copper wires will heat up and the alloy will fill all the gaps between the twisted wires. In this way you can solder small parts made of copper, brass and other alloys.

Tinned and soldered copper wire

1. Soldering wires in the trench . The stripped and twisted wires are laid in a 2-3 cm piece of aluminum tube, 0.5-1 cm in diameter, sawn lengthwise. The top is filled with a mixture of fine shavings of solder and rosin dust, and from the bottom this structure is heated with a lighter, candle or small blowtorch.

Heating the solder with a blowtorch (torch)

The mixture melts and thoroughly envelops all wire connections. After hardening, the aluminum gutter is removed and the joint is insulated.

Solder shavings can be sharpened with a coarse file.

1. A thin copper wire up to 0.75 mm can be laid on aluminum foil, sprinkled with a mixture of rosin and tin shavings, wrapped tightly and heated for 3-4 minutes. The solder will evenly fill all the elements at the soldering site; after cooling, the foil can be removed and discarded.

How to prepare solder paste

Soldering paste is sold in radio parts stores, but you can prepare it yourself. To 32 ml of hydrochloric acid add 12 ml of ordinary water, then pieces of zinc - 8.1 g. For this, enamel dishes are used.

How to tin a soldering iron: preparation and care of the soldering iron

After the dissolution reaction is completed, tin – 8.7 g is added to the composition. When the second dissolution reaction is completed, the water is evaporated to a paste-like consistency of the solution. The paste is transferred to a porcelain container, where powder is poured, which contains:

• lead – 7.4 g;
• tin – 14.8 g;
• dry ammonia – 7.5 g;
• zinc – 29.6 g;
• rosin – 9.4 g.

This paste is mixed with 10 ml of glycerin, heated and stirred.

How to solder correctly, sequence of actions:

• The parts at the soldering site are cleaned, the wires are twisted;
• the paste is applied with a brush in a thin layer;
• the surface for soldering is heated with a plasma lighter, torch, candle or alcohol tablet, or even with matches or over a fire until the paste melts;
• After melting, the soldering elements are removed from the heat source, and the solder hardens.

The paste is very effective when it is necessary to solder copper wire, small parts made of alloys based on copper, brass, such as radiators, samovars and other products.

Soldering utensils

How to install a socket with your own hands correctly

Buckets and pans with holes no more than 5-7 mm in diameter are recommended to be soldered without using a soldering iron with POS-60 solder. Leaky places on the dishes can be reliably soldered. To do this, the holes are carefully cleaned with sandpaper from the inside of the container. The hole along the edges is given a conical shape, the cleaned areas are treated with a solution of soldering acid with a brush.

  Steel x46cr13 characteristics

In order to prevent solder leakage from the outside, all bottoms or individual places where holes need to be soldered are covered with thin tin plates. Powdered solder and rosin are poured into the cleaned holes from the inside. The soldering areas are heated over an open fire until the solder melts and fills all the cracks.

For radiators, stripping and soldering are carried out from the outside. To prevent solder from leaking inside, the hole is covered with a plate of tin, galvanized iron, or can be replaced with copper or brass. The choice depends on the material from which the radiator is made. Homogeneous metals and alloys that are similar in composition are easier to solder.

After completing the soldering process of radiators, the internal and external surfaces are thoroughly washed with an alkaline, soapy solution in order to prevent the effect of acidic components on the metal.

Bottle with flux for soldering aluminum

When it is necessary to solder aluminum parts, special solders are used:

• 4:1 mixture of tin and zinc;
• 30:1 mixture of tin and bismuth;
• 99:1 tin and aluminum powder.

The sequence of surface treatment is the same as for preparing iron utensils. In order to properly solder aluminum, rosin is added to the powder, but the melting point must be above 500ºC. It is recommended to stir the solder in the hole, using a thin copper soldering iron tip.

PCB soldering paste

The composition is not much different from the paste that is used to solder without a soldering iron; the powder includes the following components:

• tin – 14.8 g;
• rosin – 4 g;
• zinc dust – 738 g;
• lead powder – 7.4 g.

For a paste-like consistency, add diethyl ether - 10 ml, it can be replaced, use glycerin - 14 ml.

Soldering sequence:

• the legs and tracks of the printed circuit board are cleaned;
• in order to solder, the legs of the parts are inserted into the holes of the board;
• places where it is necessary to solder on the board are lubricated with paste;
• the paste is heated with a soldering iron until it melts;
• The solder spreads and hardens, providing reliable electrical contact between the parts and the traces of the printed circuit boards.

Soldering lessons.

You can learn how to solder correctly by watching this video.

From the above information it follows that, if desired, and if certain materials are available at home, you can solder in various ways, achieving high-quality fastening of parts and tightness of containers.

Soldering copper pipes using a torch

You can solder with or without a soldering iron almost all metals, alloys, aluminum, brass, copper, electrical circuit wires for various purposes, metal utensils, radiator housings and other pieces of equipment.

Source: https://varimtutru.com/kak-payat-stal-v-domashnih-usloviyah/

How to solder steel parts

Often there is a need to fasten steel parts without drilling and without welding. Soldering steel will help. But how to do it correctly, because there are special nuances here. A few recommendations from experts.

What kind of steel solders well?

Some grades of steel lend themselves well to soldering, while others are soldered with great difficulty and do not want to be combined with any solder or with any flux. As a rule, soft steels "for nails" are easy to solder. At the everyday level, this can also be explained by the fact that the material is dotted with microscopic craters and irregularities. But there are also electrical grades that are especially hard and elastic, and are used for shafts and precision mechanics. It's your luck here

The question is that it is impossible for a home craftsman to determine the brand by eye. You can only find out how well a given part made of steel, or an alloy close to it, is soldered by experimentation.

How to make a tin connection - procedure

It all depends on how successfully the part can be tinned and how strong the contact of the tin solder with the steel is. In order for the contact to be satisfactory, if possible at all, the following must be done:

• steel stripping, chemical stripping under solder;
• heating the part to the melting temperature of the solder, keeping the solder on the part under flux for some time in a fluid state.

Cleaning the steel is first done mechanically, using sandpaper, to remove layers of rust and dirt. Then a composition that reacts well with iron oxides is used as a flux.

The most harmless to use, but effective in this case, is orthophosphoric acid, which can be easily purchased at a car store as a “rust cleaner.”

The required power of heating devices depends entirely on the mass of the parts.

The process of soldering two steel parts

If you need to solder two large nails, then the power of one soldering iron 100 W will not be enough. To heat up a large nail or a similar weight steel part clamped in a vice, you need to use a hair dryer. Or a gas burner.

You will also need cotton wool on a stick to supply flux to the heating zone, and a soldering iron of 50 W or more.

• The sanded steel is heated with a burner.
• Phosphoric acid is applied to the hot part and molten tin solder is immediately applied with a soldering iron.

As a rule, steel parts that can be soldered develop a very strong bond with tin, i.e. When the metal is coated, it is tinned.

The same is repeated with another detail. Then the two parts located together are heated, and additional solder is applied to the contact area with a soldering iron.

How strong is the soldering of steel, can it be made stronger?

The strength of such a connection will be determined by many factors:

• strength of bond between solder and metal,
• connection area,
• direction of the load in relation to the welded planes.

But in any case, the strength of tin soldering cannot be compared with what is commonly understood as the strength characteristic of steel or “metal welding”.

You can strengthen it by using another solder - special strong and more refractory compounds containing silver, zinc, copper, etc.

Another direction for increasing strength is to cover with solder not only the plane, but also the sidewalls of the part - covering the part with solder. Then the pull-off resistance under multidirectional loads will be greater.

Extra strong soldering, special solders

To use compounds that provide a strong connection with steel, with its own melting point of about 800 - 900 degrees, you need to use a graphite crucible.

The work should only be carried out by specialists in metal smelting. It is necessary to know the basics of metal melting, the procedure for handling melts and safety precautions. In general, soldering of steel with heavy-duty solders is performed at specialized enterprises.

Possible solder composition:

• 55% zinc, 45% copper, some silicon to increase fluidity.

The composition is melted under a layer of coal in a graphite crucible. Steel parts to be soldered are heated with a gas burner. Phosphoric acid is used as a flux. The melt is fed to the parts. As a rule, tinning and soldering are carried out during one heating of both the parts and the solder.

But such soldering of steel is more complex than simple welding.

Source: http://stroy-block.com.ua/material/623-kak-payat-stalnye-detali.html

Rules for soldering steel

Soldering, as a technology for creating permanent connections of metal products, has an ancient history. And today, despite the leading position of welding processes, soldering of steel, aluminum, copper, and many other metals and alloys continues to be successfully used in various branches of technology.

The process of soldering metal alloys of different compositions has its own characteristics. This is due to the different melting points and chemical composition of the alloys. Soldering does not apply to some grades of steel.

The essence of soldering technology

Soldering is the joining of metal parts using solder, which is a lower-melting metal that, when molten, wets the surfaces being connected.

Thus, the soldering process is associated with heating and occurs at a temperature exceeding the melting point of the solder, but not reaching the melting temperature of the metal being connected.

During the soldering process, the joined parts of the base metal do not change shape, since they themselves are not subject to melting.

The strength of the joint created is determined by the mechanical properties of the solder solder. When steel parts are soldered to each other, the connection is always inferior in strength to the base material.

The main obstacle to creating solder joints is the oxide that forms on the surface of any metal. The oxide layer does not allow the molten solder to evenly wet the surface of the part, so the metal must first be cleaned.

To protect surfaces from oxidation during the soldering process, special substances are used - fluxes. Different fluxes are used to join different materials. For example, in order to solder stainless steel, borax is used. Rosin and soldering acid can be used as fluxes for steel.

The main process that accompanies the creation of a solder joint is the heating of the workpieces. Depending on the mass of the parts being soldered and the type of solder used, heating can be carried out in the following ways:

• soldering iron;
• gas burner;
• high-frequency inductor;
• in special ovens.

For example, small-diameter wire can be easily heated with a regular soldering iron; when soldering steel pipes, you will need a gas torch, but a massive workpiece will have to be placed in a furnace.

Low alloy

Low alloy carbon steel is one of the iron alloys that is most easily soldered.

This is explained by the fact that a relatively weak film of oxides forms on the surface of steels of this type, which is easily removed by using conventional fluxes.

The process of soldering ferrous metals can take place at a relatively low temperature, not exceeding 450 ℃ in the case of using soft and low-melting lead-tin solders.

To obtain a solder joint with greater hardness and mechanical strength, harder refractory solders, for example copper-based, should be used. This soldering is carried out at temperatures up to 750 ℃.

Constructive

This type of steel is characterized by the presence of chromium, used as an alloying additive. Thanks to chromium, steel acquires the necessary mechanical characteristics.

However, the presence of this alloying component significantly complicates the soldering process, since a fairly strong and difficult to destroy oxide film is formed on the surface of structural steels.

You can solder steel with the addition of chromium using an active flux containing acids. In addition, to obtain a high-quality result, special devices are used that create a protective atmosphere in the soldering area.

In addition, the steel surface prepared for soldering is coated with a layer of powder containing metal components. This protective layer prevents oxidation of the steel surface and burnout of alloying elements during heating.

Brazed joints on alloy steels are made using hard solders containing copper, silver or nickel.

Instrumental

Tool steel has very high hardness. However, types of tool steel that do not contain tungsten change their mechanical properties when heated to 200 ℃ or more, significantly losing strength.

These types of steel cannot be soldered. To eliminate this drawback, tool steels that are subject to heating during operation are produced with tungsten additives. Such steel can be heated up to 600 ℃ without losing valuable mechanical properties.

Tool steel can be soldered using nickel-based or ferroalloy solder. Heating of workpieces is usually carried out using the induction method. In this case, fluxes containing boron and fluorine are used.

Sequence of operations

The process of soldering steel parts begins with thoroughly cleaning the workpieces from dirt, rust and traces of oil. To do this, use sandpaper, a file, or a steel brush. Rusty parts can be treated with a rust converter based on phosphoric acid. Fatty stains are removed with a solvent or alkaline solution.

After cleaning and degreasing, a layer of flux is applied to the surface of the parts. If tin is used as solder, the parts are pre-tinned. Tinning is the uniform wetting of a surface with molten tin.

After this, the parts are assembled and securely fixed in the position in which they should be after connection.

Next, the parts are heated in a suitable manner. Heating is carried out to a temperature slightly higher than the melting point of the solder used, which must be placed in the joint area.

When melted, it flows into the gap between the parts, forming a connection. After the solder has cooled and crystallized, the seam is cleaned and traces of flux are removed.

Source: https://svaring.com/soldering/tehnologii/pajka-stali

Is it possible to solder copper with tin?

Most often, at home, there is a need to solder copper pipes when installing water pipes or heating systems. Copper is a good material for water pipes. It does not corrode, has a smooth surface that ensures good water flow, does not become overgrown with deposits, and not only does not contain harmful substances, but even has bactericidal properties. Copper plumbing can last a very long time, 50 years or more.

A little theory

When soldering in general and copper tubes in particular, lap joints are usually used. They make it possible to ensure sufficient structural strength even if soft solders with relatively low strength are used. It is believed that to ensure satisfactory solder joint strength, the overlap should be at least 5 mm. In practice, much higher values ​​are usually used, which provides a good margin of safety.

Mutual overlap of elements in the pipeline is ensured through the use of fittings or pipe expansion and flanging operations. Parts of pipes and fittings are inserted into each other.

In this case, between the elements being connected, just such a gap is provided (0.1-0.2 mm) that is necessary for the action of capillary forces, which are a prerequisite for most types of soldering.

Under their action, the molten solder is spontaneously drawn into the gap, distributed evenly over the entire contact surface and tightly seals the connection. Capillary forces allow solder to be fed from below.

Copper pipes

Copper pipes come in annealed (soft) and unannealed (hard) varieties. The first are obtained as a result of annealing - heating to 600-700°C with gradual cooling. This operation returns copper to its natural ductility, lost during machining (stamping or rolling) during manufacturing.

Annealed pipe has some technological advantages over unannealed pipe. While inferior to it in strength, it is much superior to it in ductility. The value of its elongation at break can reach 40-60%. This means that the annealed pipe can be bent if necessary without fear of rupture.

Observing, of course, certain relationships between the diameter of the pipe and the bending radius (R = 3d-8d, depending on the bending method). Annealed copper pipes can prevent a water pipe from bursting when it accidentally freezes - thanks to the plastic deformation of the metal, which prevents the pipe from rupturing.

Anyone who has at least once encountered the replacement of steel “frozen” pipes is able to fully appreciate this advantage.

Annealed pipes are supplied in coils of 50 and 25 m, unannealed pipes are supplied in the form of measured pieces (rods) 3 and 5 m long.

Pipe connection methods

If you wish, you can do without fittings at all, or, in any case, with a minimal amount of them. True, for this you need to have a special, expensive tool that allows you to perform certain operations with pipes, namely bending, expanding and flanging. Using bending, you can do without corner fittings.

Expansion (increasing the diameter of the pipe end) allows you to do without couplings when soldering pipes. By using flanging, you can avoid purchasing tees (or corners, if you cut the pipe and install a plug at its end).

You just need to keep in mind that when using flanging, the outlet pipe must be smaller in diameter than the main one.

To perform all these operations with pipes, you must have manual or electric tools: a pipe bender, a beading machine and an expander.

When using pipe benders , the bending radius must be no less than 3.5d (d is the diameter of the pipe) for a diameter of up to 15 mm, and 4d for a diameter of 18 mm. When using a bending spring - no less than 6d.

Branded pipe benders are not cheap, so information about homemade pipe benders may be useful.

An excessively small radius may cause the pipe to rupture or collapse. Annealed pipes can be bent to a smaller radius, but a tight bend (less than 3d) is unfavorable from a flow point of view. Annealed pipes can also be carefully bent by hand. In this case, to avoid flattening, the bending radius must be no less than 8d.

Poorly executed bends, in which the pipe has flattened and the cross-section has lost its round shape or the inner surface of the bend has gathered like an accordion, cause turbulent flows in the pipe bend, which leads to erosion-corrosion damage.

Unannealed (solid) pipe, up to a diameter of 18 mm, can be cold bent with a pipe bender. Larger diameter pipes should be softened at a temperature of 500-600°C before bending.

The operation of the expander is based on the radial expansion of the segments of the cam mechanism inserted inside the pipe. The expandable copper pipe must be annealed (soft).

Thanks to the lever system, pressing on the tool handles creates the necessary force required for plastic deformation of the metal. Everything is very simple - insert the cam tip into the pipe, squeeze the handles and get a socket into which you can insert a pipe of the same diameter.

You can make a coupling from a piece of pipe by expanding both ends of the workpiece. If necessary, the end of the unannealed (solid) pipe can be annealed yourself.

flanging operation is somewhat more complicated than the expansion operation. It consists of two stages: drilling a hole with a special calibration drill and the flanging itself.

After the hole is drilled, it is necessary to insert into it a mandrel with sliding antennae lubricated with grease, and attach the outer part of the device to it, which serves as a stop when drawing. After that, a power tool is connected to the outer part.

Rotation of the spindle pulls the mandrel out of the hole. In this case, by spreading the antennae, flanging is carried out - bending the edge of the drilled hole outwards.

Now you can insert a bend into the pipe, which is a piece of pipe with a smaller diameter. To prevent it from protruding too much from the inside and preventing the movement of water, two protrusions are formed on its walls using a special tool. The latter rest against the socket, ensuring that the outlet is immersed in the hole to a strictly defined depth.

The described beading method involves the use of power tools, but there are also manual models.

Solders and fluxes

The use of low-temperature solders allows soldering to be performed at a temperature that has little effect on the strength of copper, but they produce a seam with worse mechanical characteristics. Solders for high-temperature soldering provide greater strength to the seam and allow high operating temperatures of the system, but in this case the copper is annealed and more skill is required, since it is easy to burn out the metal.

Low-temperature soldering is most in demand in water supply and heating. There are many low temperature lead-free solders that provide fairly good quality copper soldering. These are alloys of tin with antimony, copper, silver, bismuth, and selenium. The main part (up to 95-97%) of them is tin, the rest is other elements.

Silver-containing solders, for example, S-Sn97Ag3, containing 97% tin and 3% silver, have the best technological properties. Copper-containing solders, in particular S-Sn97Cu3 (97% tin and 3% copper), have somewhat worse, but quite good qualities. There are three-part solders containing tin, silver and copper (for example, a composition with 95.5% tin, 3.8% silver and 0.7% copper).

The most versatile and widely used is tin-copper solder. The disadvantage of tin-silver alloys is their higher cost compared to tin-copper alloys.

These solder compositions provide good seam quality and meet all the requirements for strength, durability and reliability of water supply and heating systems. Solders of other compositions are practically not used.

In fact, lead-tin solders are also suitable for low-temperature soldering of copper, but if a pipeline for drinking water is being soldered, they must be abandoned due to the harmfulness of lead.

Compositions containing zinc chloride are mainly used as fluxes for low-temperature soldering. However, it is hardly worth paying special attention to its composition when purchasing flux. There are many effective fluxes for soldering copper; you just need to purchase any composition designed for this. For example, F-SW 21 or rosin-vaseline paste, consisting of rosin, zinc chloride and technical petroleum jelly. The paste form is the most convenient for applying to parts.

Source: https://crast.ru/instrumenty/mozhno-li-pajat-med-olovom

Physical properties and technical characteristics of solder for copper soldering

Traditionally, the most common method of joining copper pipes is soldering. To create a strong and durable seam, you need to choose the right copper solder and flux, carefully prepare the surface and follow the technology.

Which solder should I choose?

When soldering copper pipes, two main types are used:

• soft, with a melting point of up to 425°C;
• solid, with a temperature range of 460-560°C.

The use of silver-containing alloys is recommended as solders . They provide high quality connections, but are expensive. Copper-phosphorus compounds are more accessible and suitable for soldering less critical connections.

Copper-phosphorus

The melting point of copper-phosphorus solder is low. Copper solder allows you to do without flux compounds . The phosphorus contained in the composition will protect the work area from exposure to atmospheric oxygen.

The suture material, formed on the basis of copper-phosphorus solder, is very durable and resistant to vibration. Therefore, phosphorous compounds are widely used when soldering heat exchanger components.

Why do solders sometimes use copper solder when soldering steel parts, but copper cannot be soldered with steel solder? The reason is the difference in the melting temperatures of steel and copper. The copper blanks will already melt, but the steel will still heat up.

At the same time, copper-phosphorus solder is sensitive to overheating , so measures must be taken to cool the joint. The product is produced in the form of a rod. Copper soldering tape is also available . Copper-zinc low-temperature solders are also used for soldering.

Silver

Pure silver composition is not suitable for soldering copper products. They mainly use silver with the addition of iron, bismuth and other elements.

Silver-based copper solder has high wettability towards workpieces and penetrates perfectly into the narrowest gaps between them. The connections do not corrode and withstand large static and periodic dynamic loads.

Ag

The chemical composition of solders for soldering copper and silver workpieces is described in GOST 19738-74. They are designated by the letters PSR XX, where the numbers determine the percentage of silver

Practical use

Compositions with a high percentage of silver (50-72) have high electrical and thermal conductivity . They are used in electrical engineering and electronics.

Alloys with a medium percentage are cheaper and are used for soldering joints that are not subject to temperature stress.

Features of tinoles

A characteristic feature of silver-containing compounds is their low operating temperature. High fluidity allows the melt to penetrate into gaps and pores and create high-quality seams.

Brazing

Brazing alloys are used for joints of larger diameter tubes and pipelines. In this case, a paste-like flux, a gas burner for heating and the necessary auxiliary equipment and tools are used.

Low temperature

Low-temperature solders melt at temperatures up to 450°C . The low temperature avoids annealing of the base material of the pipe and preserves its physical and chemical properties. Solders are prepared on the basis of tin or zinc alloys. Lead is also used as a component.

High temperature

High-temperature solder for soldering copper is prepared on the basis of silver or copper, which has a high melting point. At temperatures above 450°C, the workpieces are annealed, leading to a decrease in their strength.

Physicochemical characteristics

Properties depend on the chemical composition of the alloy. Thus, low-temperature ones have less strength, but do not reduce the strength and elastic characteristics of the material of the parts.

High-temperature ones, on the contrary, create high-strength joints that can withstand static and dynamic loads. But when using them, great care is required so as not to burn or weaken the base material.

Specifications

temperature compositions lies in the range of 645-815 ° C. The seam can withstand tensile loads up to 250 MPa. The operating temperature of the compound, depending on the composition, is 150-250°C. In addition to copper itself, such solders allow you to join brass, red bronze, cast iron, steel and nickel. They also solder aluminum. In addition, they are used to connect copper and stainless steel parts.

Methods

There are two main methods of soldering copper blanks:

• High temperature . Silver or copper based refractory solder creates a rigid and durable connection. The seam is called solid and can withstand mechanical and temperature loads. To prevent annealing from leading to a deterioration in the strength of the main parts, the finished soldering should be cooled exclusively naturally, without blowing with cold air or immersing it in liquid.

• Low temperature . This type of soldering is called soft soldering. Solders are prepared on the basis of metals with low melting points. The low temperature avoids annealing and there is no reduction in the strength of the pipes. The method forms seams with a width of 7 to 50 mm, on pipes from 6 to 100 mm in diameter.

Soft connections cannot be used when installing gas pipelines.

What will be needed in the process?

For soldering you will need:

• flux for surface treatment of the workpiece;
• solder corresponding to the selected soldering method;
• device for chamfering the end of a pipe;
• wire brush and brush for cleaning workpieces;
• pipe expander;
• measuring instrument: tape measure, measuring gauge, square, spirit level;
• burner.

A portable propane torch makes it possible to heat a joint in a few seconds . In places where the use of an open flame is unacceptable, the joints are heated with an electric soldering iron with replaceable clamps and electrodes for different pipe diameters

Technology

After the accessories and tools are prepared, proceed to the soldering itself:

Cut the part to the required length

To cut pipe blanks, pipe cutters with manual or electric drive are used. To ensure an even cut, after each revolution the pressure-regulating flywheel should be tightened by a third of the stroke. The edge should be treated with a chamfer remover and cleaned with a brush. If the connection is butt, one of the pipes should be expanded. Next, the surfaces are degreased and the quality of their mating is checked.

Apply flux to the surface of the pipe

Flux paste is applied to the inner surface with a brush built into the lid of the jar. It should be completely covered with flux, but at the same time no excess should accumulate on it.

Connecting

The parts are inserted into each other with a slight twist in both directions . This helps distribute the flux evenly.

Excess flux must be wiped off with a clean rag.

When low-temperature soldering, the turned on torch is directed towards the joint . The joint must be heated evenly, smoothly moving the torch . The coil of solder is taken in the left hand. The wire touches the gap, the solder melts and fills it.

At this point, the flame is pulled slightly to the side, allowing the solder to flow into the gap.

The soldered joint must be cooled in the usual way, by blowing or wetting with liquid. This will avoid the annealing effect.

High temperature requires a hotter flame. It is obtained by burning a mixture of propane with oxygen or acetylene with air . The joint should be heated evenly and quickly, avoiding overburning. The required temperature of the workpiece (750°C) can be determined by the dark cherry color. The soldering compound, heated but not melted by the torch, is fed into the joint area.

Experienced craftsmen immediately heat the joint exactly enough to melt and flow the soldering compound. Beginning shareholders will have to practice on training blanks. Excess melt is removed with copper tape designed for removing solder. The soldered seam should cool naturally, without blowing cold air.

After cooling, use a clean, dry rag to remove any remaining flux paste.

Basic mistakes

Beginner shareholders often make mistakes. The most typical of them are:

1. Uncorrected surface defects after cutting: scoring, chips, out-of-roundness. Soldering over defects weakens the connection, reducing its durability and tightness.
2. Poor quality degreasing.
3. Narrowing of the installation gap. A narrow solder joint will also be unreliable.
4. Underheating of workpieces. Cold parts will not be able to melt the solder with their heat and ensure its flow into the mounting gap. Cold solder joints can fall apart with a simple touch.
5. Lack of flux paste. The part of the seam surface that is not covered with flux is not cleaned of the oxide film and is not soldered.
6. Burnt joint. In this case, the flux burns out, the oxide film is not completely destroyed, and scale appears on the surface. Solder strength is significantly reduced.
7. An attempt to test the strength of a hot joint. Leads to deformation of the solder layer in the mounting gap and its detachment from the parts.

Neglecting safety requirements is also a common mistake. High temperatures, harmful fumes, and chemically active fluxes require the use of personal protective equipment. These include:

• protective glasses;
• shoes, clothing and headwear made of non-flammable fabric;
• thick split leather gloves
• respirator.

There should be no flammable materials near the soldering area; it should be well ventilated. You cannot solder in the top position.

Correctly selected soldering composition allows you to obtain reliable and durable solder joints. It is equally important to use the appropriate flux and strictly adhere to the requirements of soldering technology and safety precautions.

It is better to solder the first few seams under the supervision of an experienced solder.

Source: https://svarka.guru/payka/oborudovaniya/pripoy-dlya-medi.html