How to solder brass at home. Brass soldering technology

Brass is a widely used alloy for creating various products, so the question of how to work with it is relevant for many craftsmen. The process has certain features and difficulties; it can be performed both at home and using industrial methods. If you follow the rules, brass soldering can be done by anyone.

Nuances of technology

Brass is an alloy in which the main components are copper and zinc, and the additional elements are tin and aluminum. Metal products are always used in everyday life. When you need to connect two different objects, you resort to soldering. The method has some nuances that you should be aware of before starting the work.

The main feature of the process is the active evaporation of zinc due to exposure to very high temperatures. As a result, a dense film quickly forms, especially if the percentage of zinc in the alloy is more than 15%. It is not possible to destroy it even with the help of rosin and alcohol. Therefore, when soldering brass, it is important to use special fluxes.

It is also necessary to carefully study all stages of the process, since this is the only possible option to firmly connect two different objects into one. The essence of soldering is that molten solder is introduced between the two parts being connected, which holds them together. The main condition of the process is this: the heating temperature of the connecting element must be less than the melting temperature of the objects being connected.

Hard soldering produces stronger, heat-resistant seams. The technology is carried out according to standard rules. The advantage of the method is that you can connect objects from different materials. At the same time, their surface, structure and properties do not change, as happens during welding.

Preparatory process

Before connecting brass products, it is necessary to prepare them. To achieve the most effective result, you need to use special equipment - a gas burner. Then the soldering will be reliable, and the joint will not be noticeable.

To treat brass parts, use oxalic acid or various household products. When working with acid, you should wear gloves and do not breathe over the solution, which is obtained in the following proportion: 20 grams per liter of hot or cold water. The solution is prepared in a plastic container to avoid exposure to other metals. It is needed to clean the alloy; after processing, the product is wiped and left to dry.

To solder two different objects, you will need solder and flux, which you make yourself. For example, to obtain solder from brass, you need to stock up on 20 grams of copper and silver, which are mixed and fused with a gas burner and a graphite crucible. After which the substance is placed in cold water and pulled out when the solder has cooled.

Flux is created from borax and boric acid, taking 20 grams of each powder and diluting them with 250 ml of water.

Tools used

To connect two dissimilar products, either a gas torch or soldering irons are used. As the latter, conventional electric tools are most often used. How powerful it should be depends on the nature of the work. If, for example, parts up to 1 mm thick are connected, then a tool with a power of 80-100 W is suitable.

When soldering is done with brass, the result is a porous seam due to the evaporation of zinc. This degrades the reliability and quality of the connection. Therefore, it is recommended to overlap the products. Using a soldering iron, preparation is carried out in several stages:

Plug in for the first time and wait until the instrument stops smoking. That is, until all the substances used during the last time of use burn out.
After waiting until the tool cools down, sharpen the tip.
If the tip does not have a protective coating, then a thin layer of tin is applied to the tip.
During connection, the tool must have a temperature of at least 500 degrees Celsius.

Solders and fluxes

For high-quality bonding, you need to be smart about the choice of flux and solder. This matters when the work is performed either with a gas torch or a soldering iron. Experienced craftsmen argue that it is necessary to use a more active solder, which contains zinc chloride. It is he who is able to clean the surface of objects from the appearing films of zinc oxide during heating.

Therefore, it is better to purchase a special flux, which can be borax. If you have to work with an alloy containing a large amount of copper, then it is better to use silver or copper-phosphorus components.

When the objects being joined differ in the material of manufacture, it is especially important to know which solder is suitable. Solder for soldering brass must be compatible with the surfaces of the products and have a temperature significantly lower. If there are no strict requirements for strength and appearance, the connection is possible with tin.

How to do soldering at home

You should proceed to the direct implementation of soldering after the features of the technology have been studied. First you need to prepare the following equipment and materials:

• gas burner or soldering iron;
• flux and solder;
• borax.

The task can be accomplished without flux borax, but then the seams will be visible and the joint will not be particularly strong.

Fastening of products is carried out in the following way:

• the surface of the parts is treated with flux and sprinkled with solder shavings;
• then they are brought to a gas burner and heated to 700 degrees.

Very large products must be heated gradually.

Soldering with a gas torch

When you need to solder brass of any brand, a gas torch will help out. First, the parts are placed on an asbestos base and connected. The seam is wiped with borax-based flux, and solder is sprinkled on top.

The flame of the gas burner should fall exactly on this place. When soldering copper to brass, you should prepare a special agent in advance to remove the oxide film.

Soldering with a soldering iron

A soldering iron can also be used to achieve a strong connection between two products. In this case, a flux such as soldering or phosphoric acid is used.

Having pre-treated the surface of the products, then bring a soldering iron with solder. In soldered products, defects can be hidden in this way. Soldering is performed with a well-heated tool.

At home, you can often encounter the need to connect brass products. For example, elements of plumbing and heating systems.

You will be able to do what is required with your own hands when you have two soldering irons at home - a low-power one - 40-60 W and a powerful one - from 100 W.

Mistakes to Avoid

Due to lack of experience working with a soldering iron, some craftsmen do not heat it to the required temperature. To successfully solder brass, it is necessary to clean the tool and the surface of the parts to be joined.

Quality control

When soldering brass at home, you should take the matter responsibly and prepare the materials in advance. If you don’t have a gas burner, you can get by with a soldering iron. But in both cases, it is important to thoroughly understand the operating instructions.

How well we managed to solder brass products can be understood by the appearance of the seam, structure and mechanical strength.

Safety precautions

The torch and soldering iron are dangerous tools, so during operation you should monitor the angle of the tool or flame. It doesn't hurt to check the integrity of the wiring and plug. While soldering, do not be distracted or leave a hot soldering iron within the reach of children. Some fluxes emit harmful substances during melting, so you need to either work in a respirator or ventilate the room more often.

Advantages and disadvantages of doing it yourself

When it comes to connecting brass products, soldering is the best solution. It is necessary to study how the process is carried out, since calling a specialist every time will be expensive for the family budget. But it is the master who can perform work of any complexity efficiently and for a long time. When soldering of water supply pipes or electrical wires is required, it is better to entrust the soldering to a specialist. Therefore, due to inexperience, you can be left without light or cause a mini-flood.

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 everyone.

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.

Soldering Basics
Soldering is the process of joining several parts made of hard metals using solder, heated to the melting temperature of the solder or slightly above it. In this case, the metal of the parts being connected does not melt. Mutual dissolution, growth of crystals across the interface between two phases, or diffusion of solder and base metal, if the soldering process is carried out correctly, ensures a reliable connection. All grades of brass used in shipbuilding can be joined by soldering.

Based on the properties of the solders used, this joining method is divided into soldering with soft and hard solders. Soft solders are understood as those whose melting point does not exceed 400-450 ° C; hard solders melt at a temperature of at least 500° C.

There are several methods of hard soldering, of which gas is the most widespread. Electrical contact soldering, performed using the resistance method or the “hot contact” method, is also of practical interest. The essence of contact soldering using the resistance method is that the parts to be joined, between the surfaces of which flux and solder are placed, are clamped by the electrodes of the contact machine, through which a high current is passed. Due to the contact (transition) resistance, the base metal is heated and the solder, which has a lower melting point, is melted; soldering is carried out.

Contact soldering

The essence of electrical contact soldering using the hot contact method is that carbon or graphite is used as electrodes, which quickly heat up and melt the solder with their heat. The connection diagram of the machine for electric contact soldering is shown in Fig. 6.

The process of brazing using an oxyacetylene flame is close in nature to gas welding. The same can be said about brass soldering with some hard solders whose melting point is close to the melting point of the base metal. For example, when gas soldering brass grade JI62, which has a crystallization range within 898-905 ° C with solder grade L (Zh59-1-0.3 (melting point 860-890 ° C), a process close to the welding process actually occurs , since the base metal will be close to melting or will melt due to the small difference in its melting temperature from the melting temperature of the solder. When soldering with soft solders, heating is most often performed with soldering irons or gas torches.

Solders

There are a number of requirements for hard solders used for brass soldering, the main ones of which are given below:

1. The melting point of the solder should be 50-100° C lower than the melting point of the base metal.

Moreover, the greater the difference between the melting temperatures of the solder and the base metal, the more favorable the conditions for conducting the soldering process will be.

1. The solder must have sufficient fluidity and the ability to flow or be drawn in due to capillarity into very narrow gaps (sometimes several hundredths of a millimeter) and wet the base metal well.
2. Solder seam metal formed by melting solder| gas flame, must be dense (not have pores or slag inclusions).
3. Solder melting should be carried out at a minimum; nom release of zinc vapors.
4. The solder must provide sufficient strength, pla*| tightness and tightness of the solder joint.
5. The coefficient of thermal expansion of the solder must be equal to or close to the coefficient of thermal expansion; base metal, otherwise cracks may form in the soldered seam.

The following solders are used for hard soldering of brass:

Silver. Silver solders of standard grades are supplied in accordance with GOST 8190-56. The composition and purpose of silver solders used for soldering brass are shown in Table. 5.

In addition, silver solder of the PSrMts12-52-36 (PSr12M) brand can be used for soldering brass (Table 6).

Silver solders should be used if good spreadability, fluidity, low melting point, high strength and density of solder joints are required. Solders are usually supplied in the form of strips, cut into narrow strips before soldering. Silver solders are widely used in industry.

There is also information in the literature about the use of silver solders, which additionally contain phosphorus or cadmium (about 5%) as alloying additives.

Chemical composition and purpose of copper-zinc solders

; Brand	Chemical composition, %		Permissible impurities no more than %		Crystallization temperature range, °C	Approximate
	copper	zinc	lead	iron		appointment
PMC36	34-38	Rest	0,5	0,1	825-800	Soldering high-zinc
PMC48	46-50 ‘	Same	0,5	0,1	865-850	brasses Soldering brass with high copper content
PMC54	52-56		0,5	0,1	880-876

GOST 1534-42. Copper-zinc solders are supplied in the form of grains ranging in size from 0.2 to 3 mm(class A) and from 3 to 5 mm(class B).

For a number of reasons (significant evaporation of zinc during the soldering process and reduced quality of joints compared to joints soldered with other solders), the use of copper-zinc solders of the PMTs36, PMTs48 and PMTs54 brands has become less widespread.

Copper-zinc with additives of tin and silicon. This group of solders are copper-zinc alloys, into which tin and silicon or only silicon are additionally introduced. Silicon is introduced to prevent evaporation and burnout of zinc during the soldering process. Being a good deoxidizer, silicon forms a protective film of Si02 on the surface of liquid solder, preventing the evaporation and oxidation of zinc. In addition, with the introduction of silicon, the melting temperature of the solder is significantly reduced.

JIOK59-1-0.3 solder is widely used in a number of industries for soldering metals such as copper, steel, brass, nickel, aluminum bronze, etc., due to its good fluidity and spreadability, the absence of zinc evaporation during the soldering process with this solder , as well as high strength properties of soldered joints.

The indication in the literature that LOK59-1-0.3 solder is not suitable for soldering brass, in our opinion, is not justified, since when the brass contains more than 62% copper, the difference between the melting temperatures of the solder and the metal being joined (brass) is quite sufficient for the soldering process.

Phosphorous. The introduction of 3.5-4.0% phosphorus into copper-zinc solder sharply reduces its melting point and facilitates the soldering process. Recently, copper-phosphorus self-fluxing solders have become widespread (Table I).

The disadvantage of copper-phosphorus solders, as well as LFOK59-4-1-0.3 solder, is the increased fragility of solder joints.

Silver solders, LFOK59-4-1-OD LK80-3 and copper-phosphorus solders can be used for all soldering methods, while solders such as LOK and PMC can be used mainly for gas soldering of brass.

Fluxes

Fluxes used for soldering must meet the following requirements:

1. Have a melting temperature no less than 50° C below the melting temperature of the solder (below the solidus line).
2. Ensure protection of the heated base metal and solder from oxidation by atmospheric oxygen (in the soldering zone).
3. Dissolve and bind the resulting oxides and reduce the surface tension of the solder.
4. Have sufficient fluidity to ensure proper cleaning of the metal (especially in deep grooves) and create conditions for the spreading (penetration) of solder and connecting it to the base metal.
5. Have a relatively low specific gravity (otherwise the flux will not float to the surface and will remain in the weld metal).

The basis of most fluxes for brazing is fused borax (Na 2 B 4 07; GOST 8429-57), sp. weight 2.367 or a mixture of fused borax with boric acid (H3BO3; GOST 2629-44).

Many gas welders tend to use unfused borax (specific gravity 1.73) because it is not blown away by the burner flame. But this choice cannot be considered correct, since unmelted borax, giving up its water of crystallization during the melting process (during soldering), sharply swells, which is why it partially “slides” from the base metal. To completely remove crystallization water, a relatively long time is required, during which the borax, however, will not effectively protect the heated metal and solder from oxidation by air oxygen in the soldering zone.

When using fused borax as a flux, such phenomena are not observed. As one of the main disadvantages of fused borax as a flux, the literature sometimes notes that it is blown away by the burner flame. However, the experience of using borax when soldering brass with hard solders shows that proper preliminary (before adding borax) heating of the base metal ensures rapid melting of borax and it is not carried away by mechanical action. flame pressure. The volatilization of fused borax during the soldering process can be completely eliminated by properly regulating the direction and movement of the burner flame, for example, gradually (not abruptly) bringing the flame up.

1. a) t Ua 2 03В 2 0 3 Ka g 0-4В g 0 3

By changing the amount of borax and boric acid in the mixture, you can significantly change the properties of the flux, in particular its melting point (Fig. 7, A). As can be seen from the fusibility diagram of the Na 2 B 4 07--B 2 0 3 system, it is possible, by changing the composition of the flux relatively little, to significantly change its melting temperature.

This property of a mixture of borax and boric acid can be used when choosing a flux for soldering with hard solders that have different melting points. It is obvious that when soldering, for example, with PSr25 brand solder or, especially, PSr45 (GOST 8190-56), which is sometimes also used for soldering brass, you should not use pure borax, which has a melting point (741°C), close or higher, than the temperature of the solder itself, since there may be inclusions of unmelted flux in the soldered seam. A small addition of boric acid (10-12%) reduces the melting point of the mixture, making it possible to use this fluxing mixture when soldering with PSr25 solder. At the same time, it should be taken into account that the addition of boric acid somewhat impairs the ability of borax to dissolve and bind oxides formed during soldering.

When soldering with LOK59-1-0.3 solder, you can use pure fused borax as a flux.

It should be noted that the instructions about the supposedly required increase in the working temperature of soldering when using a mixture of borax and boric acid as a flux compared to pure borax are erroneous. As can be seen from Fig. 7, with the introduction of boric acid, at almost all ratios in the mixture, the melting point of the mixture decreases. This indicates that there is no need to increase the working temperature of soldering, especially since the latter, with a correctly selected flux composition, is determined by the melting temperature of the solder, not the flux.

The preparation of flux (a mixture of borax and boric acid) is usually carried out as described below. Crystalline borax is poured at 73 heights into a metal tray and loaded into an oven, where it is heated to a temperature of 750 ° C, i.e. above the melting point. During the melting process, the borax, giving up its water of crystallization, swells greatly. After keeping the borax in a molten state for 10-15 minutes, it is poured onto a non-metallic surface and, after cooling, it is crushed and mixed in the required proportion with boric acid.

When soldering, flux is usually used in the form of a powder, poured onto the heated surface and introduced into the liquid solder bath at the end of the filler rod. It is also known that flux can be used in the form of a paste applied to the edges of parts to be joined and<на пруток. Паста образуется разведением флюса в спирте или (что несколько хуже) в воде. Известны также случаи применения флюсов в виде пара или газа, вводимых в пламя горелки. Так в СССР предложен парообразный флюс марки БМ-1.

Flux, as is known, should mainly protect the molten solder metal from oxidation, bind the formed oxides into slags and protect the part of the base metal adjacent to the soldering area and heated to a relatively high temperature. The action of borax will cause the following reaction:

N336407 2NaB0 2 + B2O3"

2NaB0 2 + B 2 0 3 + CuO 2NaB0 2 Cu0B 2 0 3, The resulting alloy of borax, boric anhydride and cuprous oxide. These solders are easily separated in the form of slag.

Zinc chloride, an aqueous solution of zinc chloride (up to 50%) and ammonium chloride (up to 20%) or rosin are recommended as fluxes for soft soldering. According to some data, orthophosphoric acid (specific gravity 1.2-1.3) can be used.

However, all acid fluxes cause corrosion of the soldering area, so when using them immediately after soldering, it is necessary to thoroughly rinse the soldered joint. Rosin and acid-free fluxes have relatively low activity, as a result of which, when using such fluxes, careful cleaning and sometimes preliminary tinning of soldering areas is necessary. At the same time, according to some data, fluxes from LTI (Leningrad Technological Institute) according to; Their activity is superior to acid fluxes and at the same time does not cause corrosion of the soldering area. When using them, there is no need for preliminary thorough cleaning and tinning of the soldering area (which is mandatory with acid-free fluxes) and for washing the part after soldering, which is mandatory when using acidic fluxes.

According to the data, the use of LTI fluxes by eliminating tinning and using solder with a lower tin content provides tin savings of 8 to 15°/o while reducing labor intensity by 15-30% and improving the quality of the solder joint.

The disadvantage of fluxes LTI-1 and LTI-115 is the need to use intensive ventilation when soldering. 1VTUMHP1931-491-21-21-2

In some cases, beveled connections can be used (Fig. 8), providing greater strength than connections I,

1. 3 (see Table 15), however, their implementation is more labor-intensive, and therefore they are rarely used.

Connections 1, 2, 3 and 5v can be carried out using hard and soft solders, connection 4 is typical only for

soft solders, and connections 5a And 56 - only for hard solders.

Gas soldering is used for the manufacture of structures with wall thicknesses up to 5-6 mm, which, as stated above, in most cases should be considered irrational.

Considering the level of development of electric arc welding, it is currently advisable to use brass soldering with a thickness of up to 2 mm, and for small parts that exclude the possibility of using arc welding, and for somewhat larger thicknesses,

In some cases, the use of butt solder joints may be acceptable; in this case, soldering should be done with hard solders of type LOK59-1-0.3 or with silver solders, ensuring a strong solder joint.

Before butt soldering, the edges of the parts are beveled at an angle of 20-30° so that the total opening angle is 40-60° (Fig. 9).

When soldering overlapping joints with silver solders, the gaps between the elements being connected should be no more than 0.08 mm, and when soldering with LOK59-1-0.3 solder - no more than 0.5 mm. This ensures reliable flow of solder into the gap without the formation of leaks inside the products and high strength of the soldered joint, which, as is known, is higher the thinner the solder layer.

PREPARATION OF CONNECTIONS FOR SOLDERING

When hard soldering by any method, the areas to be soldered must be cleaned of fats and contaminants.

When soldering with heating with a gas flame, parts are assembled with a given gap, clamped with devices (presses, clamps, etc.) or assembled using tacks so as to eliminate the possibility of displacement of the edges of the parts. The brand of solder used for tack welding should, as a rule, be the same as for soldering.

When performing contact soldering using the resistance method (in which heating and melting of the solder occurs due to the heat generated in the joint), surfaces cleaned of dirt and grease are first coated with a thin layer of flux. Moreover, if dry powdered flux is used, only part of the surface to be joined should be covered with it, otherwise electrical contact in the joint will not be achieved and, therefore, the soldering process cannot be carried out. After applying the flux, solder is placed between the surfaces to be joined, the parts are fixed with fixtures or clamps and compressed between the machine's electrodes (portable pliers).

During contact soldering using the hot electrode method 1 * (in which heating and melting of the solder occurs due to the heat released in carbon, graphite or tungsten

electrodes between which parts are clamped) preparation of connections can be done in the same way as with resistance soldering, i.e. solder must be placed between the surfaces to be soldered. However, it is also possible that solder is added manually during the soldering process as the product heats up.

With induction soldering (where, as is known, the connection and solder are heated by currents created by a high-frequency alternating magnetic field), preparation of the connection consists of preliminary cleaning of the parts and assembling them for soldering. After assembly, the places to be soldered can be covered with flux, on which the solder is placed, which is also covered with flux on top. Then the product is ficoated in fixtures, and this is where the preparation for soldering ends. It is also possible to supply a solder rod to the soldering site after the parts have been heated.

When soldering with soft solders, the surfaces of the parts are thoroughly cleaned by any mechanical method or etching, after which they are maintained. When using LTI flux, etching of brass is not necessary, and cleaning can be done with sandpaper. The resulting roughness improves wettability.

Brass as a material has been known for quite a long time. Good physical and chemical properties have allowed it to become widespread. Brass parts also periodically develop defects (cracks, holes, breaks). These problems can be solved by soldering. In order for the result to be of high quality, it is necessary to have a good knowledge of the composition of brass, its physical and chemical characteristics, how to carry out soldering, what solders and fluxes are used for such work.

Basic information about brass

Brass can be double or multi-component in composition. It is always based on two metals: copper and zinc. In this alloy, zinc serves as the main alloying component. To impart different properties, various metals are added to its composition: tin, lead, manganese. Therefore, it is very important to know what composition of brass you have to work with. This is necessary to determine the conditions and specifics of soldering.

Modern brass is classified according to the following indicators:

Depending on the chemical composition:

• Two-component alloys. It contains only two metals, zinc and copper. The percentage of each may vary. This type is marked with the capital letter of the Russian alphabet “L” and a number. The number indicates what percentage of copper is contained in the alloy. For example, grade L85 - this alloy contains 85% copper and the remaining 15% is zinc.
• Multicomponent. They are also called special. Such alloys contain a large number of additives. They are marked with two capital letters and numbers. For example, brand LA77-2. She indicates that the composition includes 77% copper, 21% zinc and 2% aluminum. Therefore, very often special brasses get their name depending on the name of the alloying element with the highest percentage (aluminum, tin, nickel, manganese, and so on).

By degree and quality of processing:

• Deformable. These include brass in the form of wire, round tube, sheet and tape.
• Foundry. These are fittings, finished products made of brass.

• If the zinc content is in the range from 5 to 20%, then such an alloy is called red brass (tompak).
• If this percentage ranges from 21% to 36%, the brass is called yellow.

All brands of brass have similar properties. They are easy to process, have high anti-corrosion characteristics, and have sufficient strength. With a significant decrease in temperature, they retain their plasticity.

These properties have determined the wide range of uses of brass.

Application of brass

In addition to the listed positive properties, brass is a very durable and reliable alloy. Brass is used in the following areas:

• Manufacturing of pipeline fittings (adapters, valves, pipes).
• Plumbing fixtures (taps, mixers, washbasins)
• Furniture fittings (handles, latches, locks, decorative overlays).
• Production of electrical parts.
• Production of souvenirs.
• Production of tableware.
• Art casting.
• Jewelry production. Jewelers mainly use two-component alloys. It can be: yellow, red, green or golden brass.

Solders and fluxes: classification and selection methods

To obtain good soldering results, additives in the form of fluxes and various solders must be used.

Solder is a specific metal that, after melting, penetrates into metals prepared for soldering.

To achieve reliable contact, the brand of solder must have a melting point that will be significantly lower than the melting point of the brass itself. At the same time, it must have good adhesion to brass. Therefore, special solders are used for soldering brass.

Only as a last resort, if parts are soldered that do not bear much responsibility for the entire unit, and there are no high requirements for strength, ordinary tin-lead alloys are used.

Modern solders are classified as follows:

• By melting point. They are soft with a melting point reaching 400°C; semi-solid with the melting point of tin and solid. The melting point of hard solders exceeds 500 °C.
• By type of melting. Solders that melt completely or partially during the soldering process.
• According to the method of obtaining solder. We produce ready-made solders, and solders that are formed during the soldering process. This type of soldering is called contact reactive soldering.
• According to the list of chemical elements added to the composition. A fairly large number of such elements are used. From common metals zinc, tin, aluminum, to rare earth metals gallium, indium, palladium.
• According to solder manufacturing technology. They are: wire, stamped, rolled, cast crushed.
• By type of solder. They are produced in the form of wire, ready-made powder, in the form of tape and individual sheets, in the form of tablets and ready-to-use embedded parts.
• According to the method of flux formation. Solders are divided into two large categories: fluxed and so-called self-fluxing.

Solders, like brass, are marked with capital letters and numbers. By the marking you can determine which brass a particular solder is intended for. For example, if it is necessary to solder a part made of brass, in which there is a large percentage of copper, then it is proposed to use solder of the PSr12 or PSr72 brand. This solder contains a large percentage of silver. If there is a large percentage of zinc in brass, then it is advisable to use PSr40 solder. Therefore, in order to obtain a reliable connection after soldering, it is necessary to understand what loads are placed on the part being repaired. If the part is stationary and does not bear large vibration loads (for example, plumbing elements), you can safely use PMC solder. If it is necessary to ensure a strong connection, special hard solders are used, such as L-CuP6. This solder has a very high melting point - 730 ° C.

To choose the right brand of solder, you can use the following method:

• Determine the melting temperature of the parts that are planned to be soldered.
• Determine the coefficient of thermal expansion. For brass that you plan to solder and the solder it should be very close.
• After soldering, the solder should not reduce the mechanical characteristics of the repaired part.
• The solder must form a galvanic couple with the main brass part. If this is not ensured, the corrosion process will quickly occur.
• The properties of the solder must comply with all technical and operational characteristics.
• The solder must ensure good wettability of the main part during the soldering process.

Flux is a special substance that allows you to prepare the surface of the metal, that is, remove the resulting oxide deposits, grease and water stains from it. Without the use of flux, it is impossible to qualitatively solder a brass part. Fluxes are selected depending on the chemical composition of brass.

Experience shows that in order to qualitatively solder parts made from common brands of brass LS59 and L63, it is enough to have a flux consisting of zinc chloride dissolved in boric acid. If you need to solder brass, which contains lead and silicon (for example, LKS80 brand), then you need a flux containing fluorine and potassium compounds. They are also dissolved in boric acid, or borax. A similar one can be prepared at home, using the appropriate elements in the required percentage.

Today, the industry offers ready-made fluxes for brass soldering. These include: Borax flux; fluxes PV-209 and PV-209X.

Soldering methods

The brass soldering process has certain specifics. The brass heats up and the hot zinc elements evaporate. At this moment, an oxide film is formed, which is quite difficult to remove from the surface of the part and thereby deteriorates the quality of soldering. Usually brass is soldered in two ways: using a soldering iron and using a special torch.

Soldering with a soldering iron

To successfully solder brass, a soldering iron must have a power of at least 1000 W. Such a soldering iron will provide the required heating temperature for the parts themselves and the solder. It should be 500ºС and above. Low temperature soldering of brass is only possible if it has a high percentage of copper content.

The most convenient way is to solder using a soldering station, which has an adjustable soldering iron tip temperature. This adjustment allows you to set the optimal heating mode. The point is that during soldering it is necessary to avoid unnecessary overheating of the soldering area. The optimal temperature for heating the soldering iron tip is up to 350°C.

Soldering using a gas torch

The task of soldering brass can be solved using a small torch. The brass part is placed on any heat-resistant material; it must withstand high temperatures. Asbestos plates are used for these purposes.

The parts that need to be soldered are placed on this plate and aligned with each other. Preparation for soldering is the same as when soldering with a soldering iron. Next, the solder is cut into small metal chips or shavings and sprinkled on the joint of the parts. Then adjust the size of the burner flame and bring it to the soldering zone.

First, it is necessary to slightly heat the soldering area so that the solder sticks to the surface of the brass. After this, complete heating is started until a characteristic red color appears on the surface of the brass. With a correctly adjusted burner, the temperature in the soldering zone reaches 700 °C. After cooling, it is necessary to remove sagging and flux residues.

So, in order to get good results when soldering brass parts, you need to choose the right solder. Monitor the cleanliness of the soldering iron rod and the degree of its heating. You should never start soldering if the soldering iron has not reached the required temperature. Carefully prepare the surfaces of the brass part that you plan to solder (wipe off dirt and dust and degrease). Carefully monitor the degree of heating of the working area of ​​the parts being soldered.

Soldering brass has its own characteristics due to the evaporation of hot zinc, as well as the formation of an oxide film on the surface of the metal. Brasses containing up to 15% zinc are oxidized by a film, which consists of interlocked particles of CuO and ZnO. In copper alloys containing a fairly large amount of zinc, the oxide film consists mainly of ZnO, which is much more problematic to remove than in the case of a copper oxide film.

The following tools and materials are useful for soldering:

• Asbestos base;
• Gas-burner;
• Graphite crucible;
• Copper, silver, borax, boric acid.

Preparing solder

First you will need to make tinol at home, which will consist of silver and copper in a ratio of 2:1, respectively. To do this, you need to fuse silver and copper using a gas burner. Next, you need to weigh out the required amount of silver and copper, after which they must be placed in a crucible and heated with a gas burner.

A graphite crucible can be produced from graphite coals (contact trolleybus elements), which are not difficult to find at the final stops of electric transport. Regarding the size of the crucible, it should be approximately 20x20 millimeters.

Then we select a 5x40 millimeter semicircular groove to make it easier to remove the solder bead (the hot crucible is lowered into the water). Once the copper and silver are melted, you can begin mixing the tinol components using a wire.

Preparing gumboil

Thus, the solder is ready for use, but it still needs to be cooled, rolled out in a roller, and also cut into small pieces. Now you need to start preparing the flux. To do this, take 20 grams of borax (powder), as well as an equal proportion of boric acid (powder), then thoroughly mix the ingredients and pour a glass of water. Next, boil and cool the finished flux.

We work as follows:

1. You need to solder on some heat-resistant material. If you are soldering radiators, do the work thoroughly. For this purpose, we stocked up with asbestos plate. Thus, we place it on non-soldered parts, then moisten it with flux and sprinkle it with solder. Next, we begin to warm it up little by little.
2. First, we heat it a little so that the solder adheres to the parts, after which we complete the procedure until a red tint appears.
3. The solder quite simply flows into the gap between the parts, soldering them together very tightly. It is worth paying attention to the fact that the difference between the melting point of brass and solder is about 50 degrees. C, and therefore the material should not be overheated.
4. The resulting seam has one distinct color with the part being soldered.
5. This is followed by washing the product from flux: we wash the product in hot sulfur acid (3%).

Thus, we get excellent adhesion of brass products that will last for many years.