What flux to solder with brass. Soldering metals with brass

Soldering brass with a gas torch, tin, tin-lead and other similar solders is very common, although many do not dare to pick up the appropriate tool. Below we will discuss all the intricacies of this process, areas of application, as well as ways to carry it out yourself at home.

1

Soldering is one of the ways to obtain a permanent connection. It is carried out by introducing molten solder between two elements. This means that the melting temperature of the latter should be slightly lower than that of the materials of the main parts. Using this process, dissimilar metals can be joined together, and in some situations this may be the only possible method of fastening.

Many people equate this combination of metals with welding, but what they have in common is only the end result. The essence is completely different. Their most important difference is that during welding the base material melts. In soldering, only the metal bond melts, so that the integrity of the processed parts is completely preserved. Thanks to this, it becomes possible to work with fairly small elements without worrying that they are deformed, and the structure and properties of the materials being soldered will remain the same.

However, it is worth considering that compared to the same welding, the connection will be less strong. This is due to the softness of the solder, but if we are talking about brass products, then this material releases zinc when exposed to high temperatures, and the seam becomes more porous, which also negatively affects the adhesion strength. Moreover, the location of the elements also plays a role, so butt soldering is quite unreliable, it is better to do it with an overlap.

Today, it is soldering that occupies one of the leading positions in the creation of permanent connections, second only to . Thus, it is very difficult for electronics engineers who are forced to work with rather fragile microcircuits to imagine their profession without the participation of this process. In addition, solder joints are also very relevant in electrical applications, if you need to extend or simply connect wires.

This method is also used to make connections in refrigerators, heat exchangers and other installations. Very often it is used to fasten plates made of hard alloys to cutting tools. You can also attach thin-walled parts to a thick sheet. In addition, sometimes anti-corrosion treatment is carried out using tinning. In general, the scope of application is quite wide.

Soldering can be high or low temperature. In the first case, the connection is more reliable, plus it has increased thermal stability (this is due to the fact that solders for this type of processing have a higher melting point). Thus, parts after such exposure can operate at much higher temperatures compared to parts connected in the second way. However, this type also has its drawbacks, since we are talking about excessively high temperatures, it will not be possible to carry out this process with a simple soldering iron. It requires special equipment, which greatly complicates the work.

2

Most often, you have to work with a soldering iron on an alloy of copper and zinc called brass. This material is mainly found in industry and households; radiators, pipes and many other products are made from this material. Therefore, let's look at the features of working with it. Firstly, it is very important to choose the right flux for soldering brass. After all, ordinary rosin-alcohol is unable to remove the oxide film from its surface well, so it is necessary to use more active components, the basis of which can be zinc chloride.

For soldering elements in salt baths, fluxes containing borax or potassium fluoroborate have been used. Typically their content in the solution is about five percent. They promote better flow of the binder component into the gaps.

Secondly, special attention should be paid to selecting the solder for soldering brass. Silver and copper-phosphorus components are ideal for gas environments. They are also applicable for working with brass, where there is a high copper content. In the latter case, even brass can be used as solder, but its melting point must be significantly lower than that of the main alloy from which the parts are made. Brass brazing is very common. So, for example, L-CuP6 is used to connect radiators, copper pipes and other elements of heating systems. In general, hard solders are superior to soft ones, since the joint strength will be greater.

It is also important to consider the situation when the material of the parts being connected is different, for example, how copper is soldered to brass. At home, this process is quite feasible, the main thing is to know some of its features and what kind of solder should be used. When heated, an oxide film forms on the surface of brass, and excessive heat also contributes to the evaporation of zinc from this alloy, which enters the liquid metal binder. In this regard, the seams become more porous, which contributes to the deterioration of adhesion strength.

In addition, because of this property, high-temperature soldering in special furnaces is very rarely used. What about soldering in gas environments, it is better to do this using flux, but if this is not possible, then a layer of nickel or copper should be applied to the surface of brass parts. Such a solution will avoid the release of zinc and, accordingly, the connections will be more reliable. Some solders contain substances that also act as flux, which makes the job easier because you don’t have to juggle a lot of components while working.. An example is copper-phosphorus solder.

3

Having studied all the features of the process and become familiar with all possible components, you should pay attention directly to the question of how to solder brass. After all, it occurs very often in our everyday lives, and the budget does not always allow for hiring specialists, so we have to cope on our own. Moreover, all we need is:

gas burner (sometimes you can get by with a simple soldering iron),
solder,
flux,
borax.

Without the last two elements, the seam, of course, will work, but it will be quite weak, white, and the folds, if any, can come apart very quickly.

So, let's start collecting everything you need. This list includes: gas torch, asbestos base, graphite crucible, borax, solder and boric acid. Solder is prepared as follows: take one part copper and two silver, then put them in a crucible and melt them, heating them on a gas burner, not forgetting to stir. Once the mixture is homogeneous, place the container in cold water to allow the contents to cool. Then it can either be cut or used in the form of shavings.

To make flux, you will need a drill for brass soldering and boric acid, which are taken in a 1:1 ratio and filled with water. So, taking 20 grams of each component, you will need 250 ml of liquid. Now let's proceed directly to the process. We take the parts, treat their surface with flux and sprinkle with solder shavings. Then we bring it to a gas burner and heat it up to about 700 °C. Beware of overheating, because thin brass parts heat up very quickly and can become deformed. Massive elements must be heated gradually. Soldering can be considered complete. Of course, this procedure is much easier to do with a soldering iron, but it is more reliable with a torch.

When repairing them, owners have to resort to soldering technology. Since this method of joining metals has specific features, beginners may have difficulties during the work. Therefore, they are interested in how to solder brass. If you know the technology and follow the recommendations of specialists, anyone can cope with this procedure. You will find information on how to solder brass at home in this article.

About the composition of alloys

In everyday life there are many different parts containing brass and bronze. Despite the external similarity of these copper alloys, they have different compositions. Brass is one that has tin, aluminum and other metals added during production. Bronze is a compound of tin, aluminum, lead and other substances with copper. The composition of brass with the addition of tin is close to bronze, but the metal base is dominated by zinc.

What are the features of using copper alloys?

Many beginners ask the question of how to solder bronze and brass. The interest is due to the fact that soldering is associated with some difficulties. During thermal exposure, active evaporation of zinc alloy occurs, resulting in the formation of a dense film of zinc and copper oxides. It is quite difficult to destroy it. According to experts, rosin will not cope with this task.

The master will have to use special fluxes. If you use tin-lead solder, there is a risk that the joint will have low mechanical strength. Unlike copper soldering, in this case the strength indicator will be one and a half times lower. The reason for this is evaporating zinc. The choice of soldering method for bronze parts will depend on its composition. Bronze with a high content of tin and nickel should be soldered using tin-lead solders. Bronze containing aluminum and beryllium is best joined with special solders and fluxes.

About fluxes

Their task is to remove the resulting film from the surface of the metals being joined and prevent its further appearance. According to expert reviews, rosin is suitable for soldering copper products. The situation is different with brass. How to solder this alloy correctly? Which flux should I choose? Beginners often ask such questions. Experienced craftsmen advise using a more “aggressive” flux than rosin. Since metals are used as additives in the production of brass, fluxes with different compositions should be used for soldering. To work with the most common brands of brass L63 and LS59, a flux containing zinc chloride and boric acid is intended. For LKS80 with lead and silicon, the best option would be a borax-based flux containing boron, potassium and fluorine. Ready-made formulations are available on the shelves of specialized stores. Experts recommend paying attention to PV-209, PV-209X and Bura fluxes. Anyone who wants to save money can prepare flux at home.

About artisanal flux

According to numerous consumer reviews, this composition can work with different brands of brass. Preparing flux is not very difficult. You need to take 20 g of borax powder and mix it with boric acid, which will also require no more than 20 g. The dry composition of the substances is thoroughly mixed. Then the mixture must be filled with water (200 ml). Before use, the mixture should be boiled and cooled.

About solder

With the help of this molten metal soldering is carried out. In a liquid state, it penetrates into the metals being soldered and then cools, resulting in a connection. The melting temperature of the solder must be lower than the melting temperature of the metals themselves. For those who are wondering whether it is possible to solder brass with tin, experienced craftsmen recommend using solder with good adhesion. Conventional alloys containing tin and lead are best used in cases where high mechanical strength is not required. Solder is also suitable when the appearance of the joint is not important.

About solder compositions

The choice of solder depends on the brand of brass. PSr12-PSr72, brass PMC36-PMC54 and copper-phosphorus are recommended for brass with a predominance of copper in its composition. If there is more zinc in the metal, then you need to work with silver solders from PSr40 no lower. With phosphorous compounds, weak zinc phosphorus compounds are formed, which reduces the mechanical strength of the solder. For parts that are not subject to shock and vibration during operation, MPC brass solders are suitable. Note that brass can easily dissolve, so craftsmen using silver and phosphorus solders should reduce the heating and soldering time.

To work with permanently fixed parts (radiators and pipes), experienced craftsmen recommend using special hard solders with complex compositions. According to numerous consumer reviews, L-CuP6, which melts at a temperature of 730 degrees, is very popular. You can also prepare solder at home.

How to do it

When soldering brass, it is best to use silver solder. It is desirable that the melting site be a special crucible adapted for significant thermal effects. Contact carbon elements for trolleybuses can be used as a material for crucibles. When heated, they are of no value, and a home craftsman can use them to make solder. In this product, a recess of 20 x 20 mm should be made. Next, a groove should be made to it. It will be easier to remove the solder if its width is 0.5 cm.

Solder is made from silver and copper (2:1). After taking the required amount of metals, they should be placed in a crucible. Their heat treatment is carried out with a gas burner. Some craftsmen pre-crumb the consumables. In this case, the melting procedure is much simpler. Next, a steel or ceramic (porcelain) rod is added to the composition. You can solder brass when the homemade solder has completely hardened.

How to perform soldering with a gas torch

How to solder brass? The procedure is as follows:

Before starting the process, the metals must be heated. This work is performed on heat-resistant materials. Experts advise using an asbestos plate.
The parts to be soldered must be aligned with each other.
Wipe the surfaces at the soldering site thoroughly with flux.
Cut silver solder. Ultimately, it should be in the form of shavings that should be poured onto the junction of the metals.
Adjust the flame in the gas burner. To set the solder to metal surfaces, the joint is first heated with low heat.
Set the gas burner to 750 degrees for main heating. A red tint should form on the brass surface. Solder fills all the gaps, then it spreads throughout the entire joint.
Turn off the burner and allow the product to cool down. The procedure is considered completed correctly if the result is a seam that differs little from metal.
Wash the joint to remove any remaining flux.

How to solder brass with a soldering iron

This method is the most common because it is the easiest to perform. For those who do not know how to solder brass with a soldering iron at home, experts recommend following the following algorithm of actions:

At the very beginning, you need to clean the parts to be connected. Metal surfaces must be free of various foreign deposits and contamination.
Place the parts on a special fireproof stand. You can make it at home using improvised materials.
To remove all defects in the brass surface, treat the joint with flux.
Sprinkle crumbs of solder on top.
Warm up with a soldering iron.

Very often, beginners ask the question of how to solder copper to brass with hard solder. Experts advise using low-temperature soldering, which can provide a high-quality connection. For this purpose, you will need a soldering iron with a power of no more than 100 W and phosphoric acid. Before work, the surface of the product is thoroughly degreased and the oxide film is removed from it. It is better to connect metals using POS60 tin-lead solder. To start soldering brass, the tool should be warmed up well.

To work with silver solders, you will need a soldering iron, the power of which varies from 0.5 to 1 kW. Degreasing is carried out with flux - concentrated orthophosphoric acid. Borax-based flux is also considered quite effective. In the soldering zone, a temperature of at least 500 degrees is formed.

Works with stainless steel

According to numerous reviews, home craftsmen often have the opportunity to solder stainless steel with brass. Since the presence of nickel and chromium in the compositions of steel alloys does not exceed 25%, working with such materials is less labor-intensive. In addition, this composition ensures reliable connection of stainless steel parts with other metals.

The exceptions are magnesium and aluminum. If the stainless steel has a significant nickel content, then as a result of its heating to 700 degrees, carbide compounds are formed. The longer the heating, the more intensely they form. For this reason, soldering should be done as quickly as possible. The risk of formation of these compounds will be minimal if titanium is added to the alloy during soldering. According to experienced craftsmen, you should be especially careful with riveted stainless steel. This is due to the fact that cracks may appear on the surface of the metal. To prevent their formation, soldering is performed after preliminary annealing of the parts.

Progress

Soldering stainless steel is performed as follows:

First, the surface is thoroughly cleaned with sandpaper or a file.
Next, the soldering area is treated with flux, namely soldering acid.
Then the surfaces need to be tinned - apply a thin layer of solder containing tin and lead to them. It happens that it is not possible to apply solder the first time. In this case, you will have to use a brush containing metal strands. They will be much more convenient to remove the oxide film that prevents tinning.
Using a soldering iron and solder, solder the parts.

Finally

The soldering process may seem complicated only at first glance. There will be no problems if you master the technology and work with properly selected consumables.

In our practice we often have to deal with brass parts. They are well processed, soldered and then blackened. Most people solder brass with a soldering iron using regular tin solder. This method, along with its simplicity, has three serious drawbacks: the seam turns out white, noticeable, and few people manage to immediately make this seam thin; the seam turns out to be relatively weak; when bent, it can easily come apart; When blackened, tin may behave differently than brass and the weld will turn out to be a completely different color or shade. This article will tell you about the method of soldering brass using a gas torch with special solder and flux. The resulting weld is practically indistinguishable in color from the main parts, very durable and chemically much closer to brass than tin.

For soldering you need:
- gas-burner;
- asbestos base;
- graphite crucible (bath);
- silver;
- copper;
- borax;
- boric acid.

First you need to make solder. It will consist of 2 parts silver and 1 part copper. You need to fuse silver and copper (where can you get silver? - Do you know silver spoons? They are ideal). This can be done using the same gas burner. We weigh out the amount of silver and copper we need, place them in a graphite crucible and heat it with a burner. The crucible can be made from trolleybus contacts; there are a lot of them lying around at the final stops. The crucible size is approximately 20x50mm. A 5x40mm semicircular groove is selected to make it easier to remove the resulting bead of solder; to do this, lower the still hot crucible into water. When both metals melt, mix them with a steel wire - a hook. In principle, you can first melt copper (as a more refractory metal), and then add silver to the melt. Or vice versa - whoever likes it more.

The arrow shows the graphite bath. It is located in a brick "furnace".

That's it, the solder is ready. Let it cool, roll it out in a roller or flatten it on an anvil, then cut it into small pieces. You can simply grind the casting into shavings with a coarse file.

Now the flux. Take about 20 grams of borax (powder), the same amount of boric acid (powder), mix and pour a glass of water. Boil (to better dissolve the ingredients). That's it, the flux is ready. This amount of flux will last for the rest of your life. There is no need to worry about it being chemically hazardous. Boric acid is quite passive and does not harm your fingers or tools. In principle, you can evaporate the water, calcinate the already solid flux, crush it into powder and mix it with solder. The result is a dry mixture of solder and flux. But this is not for everybody.

Soldering process. You need to solder on something heat-resistant. Plates from the Buran's skin are best suited for this. But if Buran doesn’t fly over you, then you can get by with an asbestos plate. We place our parts to be soldered on it, moisten it with flux, sprinkle it with solder shavings (you only need a little bit of it) and begin to slowly heat it up. First, a little bit, so that the solder grabs the parts being soldered a little, then until red (approximately 700 degrees for this type of solder). Solder easily flows into the cracks between the parts and solders them tightly. At this stage, there are the following dangers: since the difference in the melting temperature of solder and brass parts is only about 50 degrees, you must be careful not to overheat them. Otherwise you will just get one big ingot. We must remember that small parts (for example, brass wire) heat up much faster than massive ones. Therefore, be careful. In this case, it is necessary to heat the entire structure slowly so that the large part has time to warm up.

The parts became red hot.

The resulting seam has almost the same color as the parts being soldered. This is due to the diffusion of the base metal into the solder as a result of soldering. Therefore, the same solder can be used when soldering silver - the seam will be white.

The last stage is washing the product from flux residues, which remains on the product in the form of glassy drops and sagging. To get rid of them, you need to wash the finished product in hot 3 percent sulfuric acid (or 15 percent when soldering gold). You can do this on a gas stove by placing a quartz glass test tube with dilute acid on it. The product is simply lowered into it for a short time (it must first be tied to something that does not interact with the acid) and then washed with running water.

I foresee the question: “Why can’t I use a soldering iron?” The answer is very simple: the melting temperature of solder is about 700 degrees, and a soldering iron can only give 200-250 degrees.
Those who have not used a gas burner before may ask, how long does a gas cylinder last? For normal use, consumption can be calculated at 1 liter per year.

In previous materials, we looked at electric soldering irons and gas burners used in soldering, and also became familiar with solders and fluxes.

Important!!! For all work on food equipment, ONLY LEAD FREE solder should be used.

Do not forget that when soldering, hot objects, aggressive liquids, and a voltage of 220 V are used. Be extremely vigilant and exercise caution.

In this material, let's move on to practice and solder copper. Along the way, let's look at the features of its soldering.

Soldering copper and brass are not very different from each other. The main difference is thermal conductivity, which is several times higher for copper. Therefore, brass is even a little easier to solder.

Copper and brass are soldered with tin solder; rosin, orthophosphoric and soldering acid are used as flux. You can solder with aspirin, but this is a last resort.

I prefer to solder copper with phosphoric acid, and it does not have to be stripped mechanically.

Let's look at the example of soldering two copper tubes together.

First, you need to widen one of the ends. I used thin-nose pliers for this purpose.

On the contrary, we sharpen the second end a little so that it fits into the widened part.

Before soldering, the contacting parts of the tubes must be tinned, that is, covered with a layer of tin. Yes, not just to cover, but to cover with high quality, so that the metals do not peel off from each other. To do this, the surface to be tinned must be heated no lower than the melting temperature of the solder. And since copper has a very high thermal conductivity, it will be very difficult to heat even a not very thick tube with one soldering iron.

I use a gas torch to preheat, and then quickly apply flux and use the soldering iron tip to apply and spread the solder.

At the same time, overheating a part is just as bad as not heating it up. I go by the color of copper; as soon as it starts to darken a little, that’s enough.

A well-tinned surface has a uniform shine and does not lag behind the tube even with strong scratching.

Soldering brass is a popular technology characterized by its universality of approach. As a working tool, you can use either a soldering iron or a gas torch. The process is not particularly complicated or has strict requirements. Having studied the features of the technology, the connection of brass products can be done even at home.

First of all, you need to familiarize yourself with the features of the procedure. This technology, as a method of creating permanent connections, is not as popular as soldering, since the strength of soldering is somewhat lower.

The formation of a weld occurs when a filler material called solder melts. After crystallization, the frozen composition reliably connects the workpieces.

A distinctive feature of soldering is the approach of impact on the working surface. When choosing solder, the main indicator is the melting temperature, which should be lower than that of the base metal. It does not change its state of aggregation, the properties remain unchanged. This allows you to connect workpieces with heterogeneous composition.

This is the difference between welding and soldering. When carrying out work, the weld pool includes the base metal and filler material. Together they form a seam, which invariably affects the quality of the metal that has been exposed to temperature. It is not without reason that when building a strip foundation, the frame is secured using wire rather than welding. Soldering does not affect the parameters of the base metal, which distinguishes it favorably from other joining technologies.

Let us highlight the main features of soldering:

used as filler material;
the products being connected do not melt;
materials do not interact with each other;
Suitable for connecting miniature elements.

The method is widely in demand in the field of high technology, due to the low temperature effect on the surface, which is the main indicator for temperature-sensitive components of boards and electronic circuits. Requirements for the quality of work are set out in GOST 17325-79.

Types of brass

There are two types of brass, differing in chemical composition:

Double. As the name suggests, the alloy consists of two elements - zinc and copper in varying proportions. Moreover, zinc plays the role of an alloying element. According to technical requirements, such compositions have special markings indicating the type of alloy and the percentage of elements. For example, L 63 is a two-component composition, with a copper mass fraction of 63%. The zinc content does not exceed 37%.
Multicomponent. Special formulations containing many impurities, the composition of which depends on the application. It is very difficult to select the optimal brass solder for such alloys, especially without knowing the exact ratio of the chemical elements in the composition.

Multicomponent alloys may include the following metals: aluminum, nickel, tin, manganese and others. Such compositions are often named by the name of the element with the highest content, for example, “aluminum brass”.

Fluxes

A competent choice of flux is the key to a quality connection. It cleans the surface of traces of oil, dirt and oxides and prepares it for soldering. Due to the characteristics of the material in question, it is not advisable to use neutral compounds based on alcohol and rosin. Experts recommend using active flux to effectively remove the oxide film.

An important factor is the chemical composition of the alloy. For the classic two-component material L 63, it is enough to use a solution of zinc chloride in boric acid. For multi-component alloys, it is better to purchase a universal flux for working with brass - PV 209 and PV 209X. When choosing a ready-made composition, you should carefully study the instructions with recommendations for use.

Solder

Beginning craftsmen do not know which brass solder to choose to achieve the best results.

Let's look at the main brands:

For soldering brass and copper, experts recommend using solders of the copper-zinc group. When choosing, you should pay attention to the melting point. For example, for PMC-48 it is 880 Cº.
Copper-phosphorus solders of the MF group are distinguished by their affordable price. Performance characteristics are slightly lower than those of compositions with the addition of silver.
The PSR group of silver solders belongs to the hard grades. The resulting connection is highly resistant to mechanical and vibration loads.

When soldering steel with brass, they use L-63 alloy, which has proven itself best. Release form: brass wire for soldering. It is used exclusively for working with hard-melting materials.

Brass solders with flux deserve attention. Their cost is higher than that of classic compositions, but the price is compensated by ease of use and a reduction in the number of defects in work.

DIY cooking

Many craftsmen prefer to prepare solder with their own hands at home. A mixture of two parts silver and one part copper has proven to work best..

After taking measurements, the metal is melted in a crucible and by stirring it is achieved to obtain a homogeneous mass. Cooling takes place in cold water.

The finished solder is given the desired shape, after which it is cleaned using a large file.

The optimal dimensions of the crucible are 20x20. Its basis can be graphite carbons from contact elements.

Soldering iron

The main difficulty in working with brass, as opposed to soldering other non-ferrous metals with a torch or soldering iron, is the oxide film that forms during the evaporation of zinc after heating the brass.

To solder this alloy using a soldering iron, you need a high-quality device with a power of at least 1000 W. This requirement is due to the high melting point of brass and the solders used. The exception is copper and brass alloys, whose melting point is much lower.

The best choice is a soldering station with a function for adjusting temperature parameters. The use of such equipment makes it easy to select optimal operating parameters without the risk of surface overheating.

Using the burner

You can use a gas torch to solder brass.. Special requirements are placed on the placement of the workpiece - it must be placed on a surface made of heat-resistant material.

The preparatory stage does not differ from a similar procedure before soldering with an electric soldering iron.

The process begins with gradual heating of the surface in order to increase the wetting properties of the solder. After this, the workpiece is heated to operating parameters, the achievement of which is characterized by the appearance of a characteristic red tint on the surface.

The use of flammable gas does not have any particular advantages over electrical power sources.

Stages of work

Step-by-step instructions for the process of soldering brass at home are as follows:

Cleaning and degreasing the joint.
Surface treatment with flux.
After completing the preparatory procedures, add solder, crushed to the state of chips, into the heating zone.
We begin gradual heating of the surface. It is important that the flame constantly moves to avoid overheating.
After forming the seam, we stop processing the workpiece and wait for it to cool under natural conditions.
Wash off the remaining flux.

The quality characteristics of a weld depend on the correct choice of consumables and filler materials, as well as compliance with the requirements for the technological process.

Conclusion

To obtain a high-quality connection, it is necessary to determine the composition of the brass. Based on the data obtained, he selects flux and solder for soldering. The work can be performed either with an electric soldering iron or with a gas torch.

Repairman of the 6th category Yaroslav Evgenievich Movchan. Experience – 13 years: « At work, I often encounter the need to carry out soldering work with simple grades of brass. I tried many formulations. As practice has shown, it is best to use fluxed silver solder with a metal content of 20%. The cost, of course, is high, but for critical work you can be sure of the reliability of the connection».