What alloy is called bronze - Metals and their processing

Bronze - composition, properties, application

Bronze is a double or multi-component alloy consisting of copper and other elements that improve the basic properties of the metal, except zinc. Such elements are called alloying elements. Bronze contains more than 2.5% by weight.

Manganese, tin, beryllium, lead, silicon, chromium, phosphorus, iron, aluminum and other elements are used as alloying components. Alloys are marked with the combination “Br”, letters that indicate the main alloying components and numbers indicating their content. For example: BrO5 - tin bronze, BrA5 - aluminum bronze.

The chemical composition of bronze alloys and their grades are determined by the corresponding GOSTs. You can buy bronze on our website.

Bronze, based on copper and tin, is one of the oldest alloys produced by man. In the 3rd millennium BC, bronze products appeared in Mesopotamia and Southern Iran. Everything necessary for human life was made from this alloy in ancient times. Archaeologists discovered weapons (daggers, axes, arrowheads, swords), furniture and interior items (mirrors), as well as dishes (jugs, vases, plates).

In addition, coins and all kinds of jewelry were made from bronze. Around the 5th-4th centuries BC, ancient Greek sculptors learned to cast large bronze statues; by the way, this technology is still relevant today. In the Middle Ages, bronze was used to make cannons and artillery shells. Bells have long been cast from this alloy.

By changing the composition and size of the casting, craftsmen created bells with an amazing sound.

Bronze classification

According to their chemical composition they are distinguished:

Tin bronzes are alloys with the main alloying component tin. In addition to tin, lead, phosphorus and zinc may be present as additional components. With the addition of tin, copper acquires greater fusibility, elasticity, and hardness. Consequently, the alloy is more amenable to polishing. Additional components improve mechanical, casting, and anti-friction properties.
Tin-free (special) bronzes are alloys that do not contain tin as an alloying element. They are not inferior in properties to tin bronzes, and in some they even surpass them.

According to technological characteristics, bronzes are divided into:

Deformable – well amenable to mechanical processing: stamping, corrugation, forging. their tin content is no more than 6%, which ensures the necessary ductility. Sheets, bronze wire, bronze rod, and bronze tape are made from deformable tin bronzes.

Foundry - intended for shaped castings. Various parts for machines operating in salt sea water, bearing shells, and gears are made from cast tin bronzes.

Properties of bronze

If we compare it with brass, bronze is characterized by higher corrosion resistance, strength and anti-friction properties. It is quite stable in air, salt water, carbon dioxide solutions and solutions of many organic acids. Most types of bronze can be welded and soldered with hard and soft solders.

Depending on the amount of additives, the color of bronze can be from red to white. Let's look at how alloying elements affect the properties of bronze. Tin, nickel, silicon and aluminum increase the strength, corrosion resistance, and elastic properties of bronzes.

In combination with lead, zinc and phosphorus, anti-friction properties also increase. Nickel and iron significantly refine the grain and increase the recrystallization temperature. Silicon and manganese increase heat resistance.

Chromium, zirconium and beryllium increase the heat resistance of alloys and slightly reduce electrical conductivity.

Let's take a quick look at the most commonly used types of bronze.

Beryllium bronze is the leader in hardness among other copper alloys. In the hardened state it has good ductility and manufacturability, and in the aged state it has high mechanical properties. The level of mechanical properties can be further increased by plastic deformation before aging. Beryllium bronze is used to make springs, membranes and tools.
Aluminum bronze is characterized by high density, resistance to aggressive environmental factors and chemical elements, and good resistance to sea water. This type of bronze can be processed with cutting tools. Tapes and strips of pipes are made from it.
Silica-zinc bronze makes it possible to produce products of complex shapes due to its increased fluidity in the molten state. Such bronze has a high degree of compression resistance and does not spark under mechanical stress.
Lead bronze has excellent anti-friction properties, resists shock loads well, and is also characterized by high strength and refractoriness. It is used for heavily loaded bearings.
Tin bronze has all the above properties and is the most widely used in modern industry.

Receipt

Bronze is produced by fusing copper and alloying components. The process takes place in electric induction furnaces or crucible furnaces. The smelting charge can consist of fresh metals, as well as production waste and secondary metals. Melting is carried out under a layer of flux or charcoal.

The required amount of coal or flux is placed in a heated furnace, and then copper is loaded. After melting and heating the copper to the appropriate temperature, the melt is deoxidized with copper phosphate. Next, heated alloying elements are introduced into the melt. Refractory alloying elements are introduced in the form of alloys. The melt is stirred until the components dissolve and heated to the required temperature. Before casting, the melt is again deoxidized with phosphorous copper to eliminate its oxides.

Bronze melts well and fills ingot molds evenly. The alloys are produced in the form of flat and round ingots. Ingots are processed by rolling or pressing.

The result is a wide range of rolled metal:

Application of bronze

Bronze is used in modern mechanical engineering, rocketry, aviation, shipbuilding and other industries.

Due to their resistance to mechanical abrasion and high corrosion resistance, bronze products are used for the manufacture of machine parts and devices involved in moving units in the friction process. Bronze parts require periodic replacement, that is, they are consumable.

Tin-free bronze alloys are used to make rolled products for components of chemical devices, control valves for heating systems and pipelines for other purposes.

Bronze is used for casting sculptures and monuments, as the material is durable, not exposed to atmospheric influences and is resistant to mechanical damage. Products of highly artistic forms in theaters, palaces, and halls (chandeliers, floor lamps, candelabra) are also made of bronze.

how bronze figurines are made

Source: https://cu-prum.ru/bronza.html

What bronze is made of: composition of bronze alloy, main properties and types, areas of application and marking - Machine

The chemical composition of bronze alloys and their grades are determined by the corresponding GOSTs. You can buy bronze on our website.

Archaeologists discovered weapons (daggers, axes, arrowheads, swords), furniture and interior items (mirrors), as well as dishes (jugs, vases, plates). In addition, coins and all kinds of jewelry were made from bronze.

Around the 5th-4th centuries BC, ancient Greek sculptors learned to cast large bronze statues; by the way, this technology is still relevant today. In the Middle Ages, bronze was used to make cannons and artillery shells. Bells have long been cast from this alloy.

By changing the composition and size of the casting, craftsmen created bells with an amazing sound.

Bronze as an alloy of two metals: types, composition and properties of the material

Bronze is an alloy of copper with tin, aluminum, lead, silicon and beryllium. The composition of the alloy can include a variety of metals, the names of which give the name: tin bronze, aluminum. The percentage of impurities should not exceed 2.5%.

The exceptions are nickel and zinc - copper alloys with these elements are called cupronickel and brass, respectively.

However, a small amount of zinc may still be present in the composition - its amount must be lower than the sum of all other impurities, otherwise the alloy will be considered brass.

The name itself comes from the Italian “bronzo”. The alloy was first used in the 35-33rd century BC . (exact dates have not been established) when the Bronze Age began, which replaced the Copper Age.

Thanks to improved processing of copper and tin, it was possible to obtain a fairly durable and beautiful alloy, which lasted almost until the 11th century BC.

It was used for the production of arrow and spear tips, daggers, knives, swords and other bladed weapons, for the production of furniture parts, mirrors, dishes, vases, jugs, jewelry, statues and coins.

In the Middle Ages, bronze was used to make church bells and cannons; the latter were made from special gun bronze until the 19th century.

Physical properties

The physical properties of an alloy depend on its composition and can vary significantly. Unlike brass, bronze has higher anti-corrosion resistance and anti-friction properties. It is more durable and has strong resistance to air, water, salt, and organic acids. Bronze is also easy to solder and weld .

Density: 7800-8700 kg/m3.
Melting point: 930С – 1140С.
Color ranges from red to white.
It has increased wear resistance and a low friction coefficient, copes even at low temperatures down to -250С.
Some types of bronze have high vapor resistance, thermal conductivity and electrical conductivity and are used in equipment operating in harsh conditions.

Types of bronze

Tin

Tin bronze is most widely used in modern industry. This is an alloy of copper and tin (in the classic ratio of 80% to 20%), which has good strength and hardness, is easier to melt and has high anti-corrosion resistance and anti-friction properties.

Tin bronze is difficult to forge, roll, cut, sharpen, and stamp and is generally only suitable for solid casting. A small draft (no more than 1%) allows the material to be used when creating particularly precise products in artistic casting.

Other metals can be added to the alloy if desired .

Zinc (no more than 10%) increases the corrosion resistance of the alloy and is used to create elements of ships and vessels that will often come into contact with sea water.
Thanks to the addition of lead and phosphorus, the antifriction properties of bronze can be significantly improved, and the alloy is also easier to process by pressure and cutting.

Tinless

In some cases, the use of tin is unacceptable. In this case, other metals come to the rescue, the addition of which allows you to obtain the necessary characteristics. And although tin bronze is the standard and most in demand, tin-free bronzes are not inferior to it.

Leaded or leaded

Lead bronze is an excellent anti-friction alloy, it resists pressure well, has increased strength and refractoriness. It is used for the manufacture of bearings that are subject to the greatest pressure during operation.

Kremnetzinc

Silica-zinc bronze consists of copper (97.12%), silicon (0.05%) and tin (1.14%). It is quite fluid and plastic, which allows it to be used as a material for products of complex shapes. It has increased resistance to compression, is not magnetic and does not produce sparks during processing. It is distinguished by elasticity and anti-friction properties, does not lose plasticity at low temperatures, and is well soldered. Often contains nickel or manganese.

Bronze is used in the manufacture of springs, bearings, grilles, guide bushings, evaporators and networks.

Beryllium

Beryllium bronze is the hardest of all types. It has increased anti-corrosion properties and heat resistance, is stable at low temperatures, does not produce sparks on impacts and is not magnetic. The metal is hardened at 750Co - 790Co, aged at 300Co - 325Co. Nickel, iron or cobalt are sometimes added to beryllium bronze to facilitate the hardening technology. In addition, beryllium can be replaced with nickel.

The material is used to create springs and spring parts, membranes, and for watch parts.

Aluminum

Aluminum bronze consists of copper (95%) and aluminum (5%). It has a pleasant golden color and shine, and can withstand prolonged exposure to aggressive environments, such as acids. The alloy has a higher casting density, heat resistance and increased strength, and tolerates low temperatures well. Among the disadvantages, it is worth noting weaker corrosion resistance, stronger shrinkage, as well as strong gas absorption in the liquid state.

Bronze is used to make car parts and in gunpowder production; gears, bushings, coins and medals are smelted.

Other metals

In addition to those mentioned above, bronze may also contain other elements. Nickel and iron increase the recrystallization temperature and promote grain refinement. Chromium and zirconium reduce electrical conductivity and increase the heat resistance of bronze.

Marking

To choose the right metal option, just look carefully at its markings. This will help to accurately determine the features and characteristics of the selected species.

The letters “Br” come first - this means “Bronze”. Then one or more letters are located in a row, behind which additives are hidden: O - Tin, A - Aluminum, K - Silicon, N - Nickel, Mts - Manganese, F - Iron, S - Lead, F - Phosphorus, C - Zinc, B - Beryllium. Next, numbers are written through a hyphen - this is the percentage of each additive in turn.

For example, the designation Br A ZH N -10 -4 -5 can be deciphered as follows: Bronze containing Aluminum (10%), Iron (4%) and Nickel (4%).

Application

Bronze is actively used in industry and in a variety of fields. First of all, bronze is used in rolled products of the same name: it is produced in the form of pipes, wire, sheets and rods.

The metal can also be found in the automotive, chemical, food, construction and fuel industries. It is used to produce gears, bearings, bushings, springs and other parts that are exposed to aggressive environments and often operate under high pressure.

Unlike brass, bronze tolerates mechanical loads and is more ductile.

Metal is used to produce art objects, sculptures, forged items, jewelry, dishes and artistic objects.

Source: https://stanok.guru/cvetnye-metally-i-splavy/bronza/chto-takoe-bronza-vidy-splava-sostav-i-svoystva.html

Classification, brands, characteristics of bronze compositions

The number of types of bronzes is huge. The metal, invented thousands of years ago, is used today in various fields of production. Some brands combine unique qualities and are sometimes simply irreplaceable. What kind of material this is will be discussed in the article.

What is bronze

This is an alloy whose main component is copper. Alloying components include tin, aluminum, silicon, beryllium, lead and others. It should not be confused with brass - it is an alloy of copper and zinc, and with cupronickel - copper with nickel.

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Alloying elements have different effects on the characteristics of the material:

Classification

Most often they are divided into categories according to three criteria - chemical composition, processing method and structure.

By chemical composition, depending on the presence of tin:

The second ones, in turn, are:

Aluminum;
Siliceous;
Manganese.

There are also brands of beryllium bronze, lead bronze and others. This depends on the presence of alloying elements.

By technological properties (processing method):

Pressure-processed (deformable);
Foundry.

By structure:

Single-phase - consist of solid solution crystals of one type;
Biphasic - there are crystals of two different phases.

Where is it used?

The qualities of alloys depend on alloying components. Accordingly, the areas of use of the material are very different:

High precision castings. Some materials exhibit low casting shrinkage.
Anti-friction elements. Those that work with constant friction. Including in steel-bronze friction pairs. The “wearlessness effect” is associated with these same properties.
Critical structural elements operating under variable loads.
Gears, cogwheels.
Parts of mechanisms operating in aggressive or wet environments. For example, in salt water.
Springs, membranes - due to good elastic properties.
Electrical products, watch mechanisms, parts of aircraft navigation devices.
Household use – accessories, fittings, plumbing products.
Jewelry production.
And of course – sculptures, decorative items, household items.

How to produce

Metal is cast from pure components or from alloys in the form of pigs.

First of all, copper is mined in deposits. It occurs quite often. It is mined from native copper and minerals. Metal is obtained from the latter in several ways. The most common are oxidative annealing and fire refining.
Then the composition of the charge is determined. This depends on the composition of the brand and on the available raw materials.
Copper smelting is carried out in special furnaces. The process takes place in several stages:

. Raw materials are loaded into dry heated crucibles.
Melting. Melting is carried out with the addition of charcoal (flux) so that the metal is less oxidized.
Phosphorous copper is introduced into the well-heated metal, playing the role of an acid catalyst.
After exposure at high temperature, preheated alloying and binding components (ligatures) are introduced.
Liquid metal is cast into sand or metal molds.

BraZh9-4

This is tin-free aluminum bronze. Deformable. Has anti-friction qualities. Aluminum gives it resistance to corrosion, and iron improves its structure, wear resistance, and strength qualities.

This alloy is one of the inexpensive ones. There's no tin. At the same time, BraZh9-4 is well processed, works in friction pairs, and resists corrosion. It often replaces expensive types of metal with tin.

An important quality - it works even at high temperatures. It is hardened at a temperature of 950 degrees, then released at 250-300 degrees for 2-3 hours. After heat treatment, the hardness and ductility of the parts increase.

BrAZh9-4 is made from copper with aluminum additives and up to 2-4% iron impurities. According to GOST 18175-78 it also contains other elements:

Physical properties of BrAZh9-4

T – temperature

E 10– 5 – Modulus of elasticity of the first kind

a 106 – Coefficient of thermal (linear) expansion

l – Thermal conductivity (heat capacity)

r – Density

C – Specific heat capacity

R 109 – Electrical resistivity

Patina on bronze items

In general, patina is a coating or film on copper alloys and copper. It is because of this that some bronze items have a noble greenish-white color.

Patina can be natural or artificial.

Natural patina is an oxide-carbonate deposit on the surface of products that appears under the influence of the environment. The film is formed with different intensity. This depends on the environment in which the product is located (air, vapors, gases, the content of chlorine salts in water and air). The natural layer protects the item from further corrosion.

Artificial patina is the same film, but it was formed after applying special compounds to the object. Usually these are acids and sulfur.

Patination of products is done to give the product a noble, vintage, and decorative look. Before this, the natural layer of patina is carefully removed. Apply the patination mixture and heat the product. Patination compounds are usually very toxic.

Standardization of alloys

There are several thousand standards regulating the production of bronzes. For example, these are groups of standards:

Containing grades of alloys;
Containing technical specifications for the assortment (rods, ingots, pipes and others);
Regulatory methods of control and analysis of composition.

Here are the main current standards. Update date 08/10/2017:

Classification, grades, characteristics of bronze compositions Link to main publication

Source: https://oxmetall.ru/metalli/bronza/klassifikatsiya-bronzovyh-sostavov

BronzeMania

The main component of bronze is copper, to which other metals (usually tin) are added. At the same time, the share of other substances is no more than 2.5%, which makes it possible to improve the performance of the resulting alloy.

If copper is combined with zinc, brass is obtained; when zinc is replaced with nickel, a cupronickel composition is obtained. There are other options. For example, BrA5 is a type of bronze obtained by adding aluminum.

We work with the BrO5 brand, made on the basis of tin, since this material fully complies with state requirements.

A little about history

The first bronze products appeared in the 3rd century BC. The Middle East is considered the birthplace of this amazing metal - the oldest finds of a compound of copper and tin were found in Iran, as well as Syria, Turkey and Iraq. Most often, household and work items were made from bronze. The most common surviving items are household, military and jewelry items.

Then came a period when this metal became the main source of the monetary industry - coins of various denominations were made from it. Around the 5th century AD. The production of bronze sculptures began in Hellas. This is where the tradition of making bronze miniatures and figurines originates, which is still relevant today.

With the onset of the Middle Ages, bronze became part of weapons and became the main resource for casting cannons, cannonballs, and shells. Bell casters also paid attention to this metal - bronze makes beautiful products that give a deep and pleasant sound.

Bronze spear tip (7th-4th century BC).

How do the species differ?

Alloys are classified depending on the selected components. Bronze made with the addition of tin often also contains lead or phosphorus - this provides an alloying effect. Due to tin, the alloy becomes harder and more durable, withstands melting better and retains its shape well. The resulting material is easy to grind, and the presence of special components allows you to achieve higher performance and visual performance.

There is also bronze, which does not contain tin. Such options have a new structure that differs from the traditional one, but in terms of their properties they are almost equal to the classic alloy.

The technical properties of a metal can affect its performance.

Casting material is formed by the method of making decorative and stylish products (for example, our products). It is also widely used in the production of bearings, parts of complex mechanisms, as well as components for devices designed to operate in sea water.

Deformable materials are designed to be formed mechanically. In this case, the metal is cut, forged, and covered with corrugation. As a rule, this option is flexible and relatively soft - cables, tapes, rods and sheet products are produced from it.

Bronze rod.

Properties of bronze

When considering this alloy in comparison with other metal mixtures (for example, zinc composition), it is worth noting that real bronze is impervious to natural processes of destruction, lasts a long time and is resistant to aggressive influences (vibration, friction). It also remains durable and beautiful even with prolonged contact with water, air, acidic environments or salt solutions. Most types of bronze can be soldered or welded.

The color of the alloy depends on the components included in its composition. The lightest type is white. Dark classes have a reddish tint.

The following additives affect the tone and quality of bronze:

zinc and lead reduce susceptibility to friction;
aluminum and silicon extend service life, protect against corrosion and deformation;
nickel and iron increase the ability of the alloy to recrystallize, making the substance smooth and homogeneous;
silicon or manganese is added to increase resistance to rust, oxide deposits and intense heat;
a material not intended to conduct electricity is made with the addition of chromium or beryllium.

The most popular classes of bronze alloy used in industry are:

Beryllium (due to hardness). Can be hardened and is elastic. With the natural or artificial aging of a metal, its increased resistance to mechanical processes is manifested. This indicator is often enhanced by preliminary deformation. Serves for the manufacture of large and small machine parts, as well as for the production of equipment.
Aluminum (due to high density). It is resistant to chemicals, does not change under the influence of natural factors, and is suitable for use in sea water. Easy to process and cut, popular in the production of flat and strip products.
Silicon-zinc (advantage: excellent fluidity). Does not create sparks during machining (turning, milling). Suitable for casting complex or decorative shapes.
Lead – resistant to friction and shock. Due to these indicators, it is more often used for parts that carry a large load.
Tin - combines all the above advantages, and therefore is in greatest demand.

How to get bronze

Bronze making is a demanding and rather difficult process in which auxiliary metals are introduced into molten copper. Smelting is carried out in forges or induction furnaces. For heating, natural fuel (coal) or flux is used.

The first stage is placing copper in the furnace and heating it until it reaches a liquid state. After this, phosphorous copper is introduced into the substance, to which alloying components are later added. The resulting alloy is mixed, and a new processing temperature is set. At the final stage, copper phosphorous is again used, which allows you to get rid of any oxidation.

Melting bronze is simple, and therefore this metal is often used for casting art objects and miniatures. Using special forms and filling them out correctly, the specialists of the Bronzamania workshop produce products of ideal appearance. Blanks intended for artistic casting are made in round or flattened format.

Bronze in a molten state.

Application of bronze

Impeccable performance qualities have made bronze one of the most common materials in mechanical engineering, aviation, shipbuilding and large industry. This metal is not susceptible to moisture, does not wear out, and is almost impossible to deform. Therefore, bronze is used in the production of rolled products intended for use in aggressive chemical environments, as well as for the production of parts and pipes of various profiles.

Reliability and long service life are additional characteristics due to which bronze has become widely known in the field of sculpture and art. Interior parts are made from it - candlesticks, chandelier bodies, decor. Therefore, the specialists of the Bronzamania workshop can guarantee the long service life of all products available for sale - our products retain their beautiful appearance and functionality for decades, without reacting to weather conditions and other adverse factors.

Ready product.

Source: https://bronzamania.ru/blogs/blog/vidy-bronzy

Composition of bronze: alloy of copper with other metals, explanation

Bronze is a metal obtained by mixing molten copper and some other metals and non-metals.

As a rule, the amount of copper additive components does not exceed three percent, but there are exceptions to this rule - zinc and nickel can be added in large quantities. Such alloys are called brass and cupronickel (cupronickel), respectively.

In other alloys, zinc may also be present, but with a limitation: its amount should not exceed the sum of the other added metals. If this happens, the alloy will be brass.

Manufacturing methods and characteristics
Physical data
How to make bronze
Varieties
Tin bronze
Tin-free
Marking

This metal alloy appeared about five and a half thousand years ago . It was then that the Bronze Age began. Until that time, only copper was smelted - this metal was the basis of all tools.

When the melts of copper and tin happened to be combined, another metal was obtained, which was called bronze - an alloy of copper and tin, harder than the original metals.

It immediately found wide application in all spheres of human life: it was used to make bladed weapons and kitchen utensils, mirrors and jewelry, coins and sculptors’ creations.

Medieval bronze craftsmen cast bells for the needs of the church and cannons for the army. Specially made bronze was used to cast the cannons. This technology existed until the nineteenth century. Below are some interesting facts about bronze.

Physical data

The characteristics of the alloy are determined by its chemical composition and can vary within certain limits. Bronze is less susceptible to corrosion and provides better metal-to-metal glide than brass. It has higher strength and is less susceptible to atmospheric influences (water and air) and better resists salts and organic acids. It is easy to machine, it can be soldered and fastened by welding. Some physical characteristics of bronze:

specific gravity from 7.8 to 8.7 tons/cu.m. meter;
melting point of bronze – melts when heated from 930 to 1140 degrees;
color changes from red - the color of copper, to white - the color of tin;
wear resistance and good sliding on metal determine the scope of application as sliding bearings; they work well in any temperature conditions;
There is high electrical conductivity and heat transfer, resistance to steam, which contributes to the manufacture of parts for equipment operating in extreme situations.

How to make bronze

Melting and mixing copper melts and additives of different metals, which make it possible to give the alloy certain required characteristics, leads to the production of an alloy metal such as bronze. The manufacturing process involves electric induction furnaces and crucible forges; with their help, any alloys with copper can be produced.

Melting is carried out with flux additives, and the initial raw material for smelting can be either copper ore or copper scrap. Typically, scrap copper is added to the melt along with the filler metal during the smelting process. When smelting only copper ore, the following operations are performed:

the furnace is heated, copper ore with flux additives is placed in it, and melted at a temperature of about 1200 degrees;
a chemical oxidizer is added - phosphorous copper, half could be loaded as part of the flux, and the rest is additionally loaded with a ladle;
during melting, filler metals are added to the deoxidized molten copper, preheated to one hundred degrees;
After settling the melt for half an hour, the floating slag is removed from its surface, and the resulting alloy is distributed into molds.

When using scrap copper, the procedure for making bronze is the same.

Varieties

Based on the ratio of the content of the main components of bronze - copper and tin, two main types are known: tin, when the main filler material is tin, and tin-free, if tin is present in very small quantities.

Tin bronze

Classic or tin bronze is a universal material not only in industry, but also in other spheres of human activity. In this alloy, there are 80 parts of copper to 20 parts of tin; it melts well, has high strength, is quite hard, does not corrode, is wear-resistant and helps reduce friction between metals.

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These advantages of tin bronze lead to difficulties in some other respects: the alloy is difficult to forge and cut, sharpen sharp edges and stamp, but it is easy to make castings from it. The settlement when cooling the pour does not exceed one percent, which allows the material to be used in artistic products of particular precision.

additives of other metals and non-metals may be included in its composition

zinc in an amount of up to 10% improves anti-corrosion properties; parts made from this alloy are used in shipbuilding, where the aggressive environment is salt water;
Lead and phosphorus contribute to better sliding of bronze products over other metals; such an alloy is easier to cut and stamp.

Tin-free

Bronze without tin - sometimes the use of tin in the alloy is not allowed, and the required characteristics are obtained by adding other metals. Modern technologies make it possible to select additives in such a way that products made from tin-free bronze completely replace products made from classical bronze.

Lead bronze is an alloy that glides well over metal, can withstand high pressure, is very durable and does not melt easily. Its scope of application is bearings operating under high pressure.

Silicon - 97% copper, a little tin and five hundredths of a percent silicon, it is added to increase electrical conductivity and such bronze is used as cores of telephone cables. It is non-magnetic, easily soldered, elastic and resistant to low temperatures. Additionally, it may contain manganese.

Beryllium is the hardest. This alloy is very resistant to corrosion and extreme temperatures, both positive and negative. It is a non-magnetic metal and does not produce sparks during collisions. Additionally, nickel or cobalt can be added to it. Elastic products are made from the alloy - springs, membranes, plates.

Aluminum - the composition is simple, five percent aluminum, the rest is copper. The color of bronze is shiny golden, it is resistant to chemicals - acids. It is strong in hardness and heat-resistant, retaining its properties even at extremely low temperatures.

It resists corrosion poorly and exhibits significant shrinkage during casting. For its beautiful color it is used in jewelry production, making coins and medals.

Physical properties predetermine the use of the alloy in parts of automotive products, gunpowder and pyrotechnic production.

Bronze is an alloy. Characteristics of bronze

Bronze is an alloy based on copper. Auxiliary metals can be nickel, zinc, tin, aluminum and others. In this article we will look at the types, technological characteristics, chemicals. composition of bronze, as well as methods of its production.

Lead bronzes

This subtype of cast tin alloys is used in the manufacture of bearings, oil seals and shaped castings. Such bronzes are characterized by low mechanical properties, as a result of which, in the process of manufacturing bearings and bushings, they are simply applied to a steel base in the form of a very thin layer. Alloys with a higher tin content have higher mechanical properties. Therefore they can be used without a steel base.

Alloys processed by pressure are usually divided into the following groups: tin-phosphorus, tin-zinc and tin-zinc-lead. They have found their application in the pulp and paper industry (they are used to make meshes) and mechanical engineering (the production of springs, bearings and machine parts).

In addition, these materials are used in the manufacture of bimetallic products, rods, strips, strips, gears, gears, bushings and gaskets of highly loaded machines, instrument tubes, and pressure springs. In electrical engineering, the widespread use of bronze (deformable) is explained by its excellent mechanical properties (along with high electrical characteristics). It is used in the manufacture of current-carrying springs, plug connectors, and contacts.

In the chemical industry, tin bronzes are used to produce spring wire, in precision mechanics - fittings, in the paper industry - scrapers, in the automotive and autotractor industries - bushings and bearings.

These alloys can be supplied in extra-hard, hard, semi-hard and soft (annealed) states. Tin bronzes are usually processed cold (by rolling or drawing). Hot metal is only subjected to pressing. Under pressure, bronze is perfectly processed both cold and hot.

Beryllium bronze

This is an alloy belonging to the group of dispersion-hardening metals. It has high mechanical, physical and elastic properties. Beryllium bronze has a high level of heat resistance, corrosion resistance and cyclic strength. It is resistant to low temperatures, does not magnetize and does not produce sparks upon impact. Hardening of beryllium bronzes is carried out at temperatures of 750-790 degrees Celsius.

The addition of cobalt, iron and nickel helps slow down the rate of phase transformations during heat treatment, which significantly facilitates the aging and hardening technology. In addition, the addition of nickel helps to increase the recrystallization temperature, and manganese can replace, albeit not fully, expensive beryllium.

The above characteristics of bronze allow this alloy to be used in the manufacture of springs, spring parts, and membranes in the watch industry.

Copper-manganese alloy

This bronze is distinguished by its special high mechanical qualities. It is processed by pressure, both cold and hot. This metal is characterized by increased heat resistance and corrosion resistance. An alloy of copper with the addition of manganese has found wide application in furnace fittings.

Silicon Bronze

This is an alloy that contains nickel and, less commonly, manganese. This metal is distinguished by ultra-high mechanical, antifriction and elastic properties. At the same time, silicon bronze does not lose its ductility at low temperatures.

The alloy is easily soldered and can be processed under pressure at both high and low temperatures. The metal in question is not magnetic and does not spark upon impact.

This explains the widespread use of bronze (silicon) in marine shipbuilding in the manufacture of antifriction parts, bearings, springs, grilles, evaporators, grids and guide bushings.

Casting tin-free alloys

This type of bronze is characterized by good corrosion and anti-friction properties, as well as high strength. They are used for the manufacture of parts that are used in particularly difficult conditions. These are, for example, gears, valves, bushings, gears for powerful turbines and cranes, worms that work in tandem with hardened steel parts, bearings that operate under high pressure and shock loads.

How to make bronze?

The production of this metal must be carried out in special furnaces used for smelting copper alloys. The charge for bronze can be made from fresh metals or with the addition of secondary waste. The smelting process is usually carried out under a layer of flux or charcoal.

The process using a charge of fresh metals occurs in a certain sequence. First, the required amount of flux or charcoal is loaded into a very hot furnace. Then copper is placed there. After waiting for it to melt, increase the heating temperature to 1170 degrees.

After this, the melt must be deoxidized, for which phosphorous copper is added. This process can be carried out in two stages: directly in the furnace and then in the ladle. In this case, the additive is introduced in equal proportions. Next, the necessary alloying elements heated to 120 degrees are added to the melt.

Refractory components should be introduced in the form of alloys. Next, the molten bronze (the photo below demonstrates the smelting process) is mixed until all added substances are completely dissolved and heated to a given temperature.

When the resulting alloy is released from the furnace, before casting, it must be finally deoxidized with the remainder (50%) of phosphorous copper. This is done to free the bronze from oxides and increase the fluidity of the melt.

Smelting based on recycled materials

To make bronze using recycled metals and waste, melting should be done in the following order. First, copper is melted and deoxidized with phosphorus additives. Then recycled materials are added to the melt.

After this, wait until the metals have completely melted and introduce alloying elements in the appropriate sequence. If the charge consists of a small amount of pure copper, the circulating metals should first be melted, and then copper and alloying elements should be added.

Melting is carried out under a layer of flux or charcoal.

After melting the charge and heating it to the required temperature, the final deoxidation of the mixture with copper phosphorus is carried out. Next, the melt is covered on top with calcined coal or dried flux. The consumption of the latter is 2-3 percent by weight of the metal.

The heated melt is kept for 20-30 minutes, stirred periodically, and then the separated slag is removed from its surface. That's it, the bronze is ready for casting. To better remove slag, you can add quartz sand to the ladle, which thickens it.

To determine whether bronze is ready for casting into molds, a special technological test is carried out. The fracture of such a sample must be uniform and clean.

Aluminum bronze

It is an alloy of copper and aluminum as an alloying element. The melting process of this metal differs significantly from those given above, which is explained by the chemical characteristics of the auxiliary component. Let's look at how to make bronze using aluminum alloying components. When producing this type of alloy using recycled materials in the charge, deoxidation with phosphorous components is not used.

This is explained by the fact that phosphorus has a lower affinity for oxygen molecules than aluminum. You should also know that this type of bronze is very sensitive to overheating, so the temperature should not exceed 1200 degrees. In an overheated state, aluminum oxidizes, and the bronze alloy is saturated with gases.

In addition, the oxide formed during the melting of this type of bronze is not reduced by adding deoxidizing agents, and is very difficult to remove from the melt. The oxide film has a very high melting point, which significantly reduces the fluidity of bronze and causes defects. Melting is carried out very intensively, at the upper limits of heating temperatures. In addition, the finished melt should not be kept in the furnace.

When melting aluminum bronze, it is recommended to use a flux as a coating layer, which consists of 50% soda ash and 50% cryolite.

Before pouring into molds, the finished melt is refined by introducing manganese chloride or zinc chloride into it (0.2-0.4% of the total mass of the charge). After this procedure, the alloy should be kept for five minutes until gas evolution completely stops. After which the mixture is brought to the required temperature and poured into molds.

In order to prevent segregation, it is recommended to add 2-2.3% nickel in the form of copper-nickel alloys to molten bronze with a high content of lead impurities (50-60%). Or, as a flux, it is necessary to use sulfate salt of alkali metals.

Nickel, silver, manganese, if they are part of bronze, should be added to the melt before the tin addition procedure. In addition, to improve the quality of the resulting alloy, it is sometimes modified with minor additives based on refractory metals.

Source: https://FB.ru/article/140126/bronza---eto-splav-harakteristiki-bronzyi

What bronze is made of: composition of bronze alloy, main properties and types, areas of application and marking

Since time immemorial, humanity has been mining bronze. Many archaeological excavations, in which the most ancient artifacts were found - bronze products, confirm the spread of this alloy in the distant past.

It was used both for military purposes - to make bladed weapons, cannons and cannonballs for them, and to create beautiful works of art - jewelry and sculptures.

One of the most famous places where bronze items were found was located in the Kuban River area. In this place, archaeologist Nikolai Veselovsky in 1897 excavated the so-called Maykop culture, which existed in the second half of the 4th millennium BC.

Bronze artifacts found in the Maikop burial mounds were made mainly from an alloy of copper and arsenic, so it is believed that historically these alloys, called arsenic bronzes, .

It was in no way inferior in its properties to alloys of copper with tin or lead, and even surpassed them in a number of characteristics . It was widely used in various areas of human activity of those times, from the manufacture of critical parts to jewelry.

Bronze composition

Bronze is an alloy of copper with metals such as tin, aluminum, lead, beryllium, and non-metals arsenic, silicon and phosphorus. In addition, such alloys can be additionally alloyed with phosphorus, zinc, manganese, iron and nickel.

The composition of bronze depends on the grade of the alloy and is indicated in its designation. For example, the composition of an alloy labeled BrAMts7−1 includes 7% aluminum, 1% manganese and 92% copper .

Thus, the main component of this metal is copper (from 35% to 90% and above). The second component can be either arsenic, or tin or beryllium, lead, aluminum, silicon and other components. To impart special properties, additional components can be added - zinc, iron, nickel, manganese, phosphorus and others.

Features of bronze and properties

The main properties of all bronze alloys are ductility and hardness. Depending on the ratio of the main and additional components, a wide variety of new properties can be obtained. In addition, the amount of copper in the alloy determines its color.

So, golden bronze will be obtained if the alloy contains about 85% copper, and if its amount is reduced to 50%, an alloy will be obtained that has a silvery color. Reducing the amount of copper to 35% and below will lead to the output of gray and even black bronze, and increasing the amount of copper to 90% and above will lead to the formation of red bronze.

One of the old brands of bronze alloys is bell bronze , which is still used today for casting bells. It contains 20% tin and 80% copper. Its disadvantage is increased fragility due to the high tin content in the alloy.

As mentioned above, the most commonly used are alloys of copper and tin with the addition of a small amount of other components. The widespread use of such alloys is due, first of all, to historical reasons that led to the displacement of arsenic bronze from production.

Such reasons are the following:

the development over many centuries of deposits of tennantite and other faded ores rich in copper and arsenic. Such ores were most convenient for the production of arsenic bronze, since they did not lie very deep, which made the production process cheaper compared to other sources of copper and arsenic;
the high toxicity of the production of such bronze, caused by the presence of arsenic in the deposits, which inevitably led to loss of health and further ability to work for experienced metallurgists and blacksmiths;
unsuitability of metallurgical defects and broken products made of arsenic bronze for further remelting into high-quality metal. At best, such products were used to make jewelry or non-essential parts.

The alloys of copper and tin that replaced arsenic bronzes, although they were more expensive to produce, were economically preferable , since the development of horse-drawn transport and the resulting establishment of trade relations between cities and countries led to an increase in the import of non-arsenic bronze.

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Types of bronze and characteristics

The development of large-scale industrial production generally led to the fact that tin bronzes became almost the most widespread type of bronze. And only in the last hundred years this type began to be replaced by copper alloys with tin substitutes, such as aluminum, silicon and, especially, beryllium bronzes.

Thus, the following types exist:

tin-free. It includes bronze, in which the second components are aluminum, silicon, beryllium and other metals and non-metals. Each of these components gives it special properties. For example, aluminum gives the alloy increased anti-friction properties and high corrosion resistance, beryllium increases strength and hardness, and silicon and zinc improve its fluidity and abrasion resistance;
tin. A copper-tin alloy in which copper predominates. It is one of the first to be mastered by man. It has high hardness and strength compared to pure copper, and is also more fusible. In such alloys, tin is always the second most abundant after copper and the main alloying component.

The third in quantity are additional components such as arsenic, zinc and lead . Due to its very low shrinkage, this metal is mainly intended for casting, as it is difficult to work with pressure, cutting and sharpening. Even the tendency to segregation and low fluidity do not prevent the use of this alloy for the manufacture of configurationally complex castings, including in artistic casting.

Bronze with the addition of zinc is called “Admiralty ” and is used for the manufacture of parts that have frequent or constant contact with sea water (shipbuilding). This feature is due to the fact that zinc gives the alloy increased corrosion resistance in the specified environment.

However, to make bronze resistant to corrosion in salty seawater, it is increasingly being enriched with aluminum and nickel . Such alloys, often called “marine”, are used to manufacture elements of oil platforms operating on sea and ocean shelves.

To give bronze additional characteristics, of phosphorus, silver, zinc, arsenic, manganese and other components are alloyed into it Thus, adding a small amount of silver increases the electrical conductivity of bronze and makes it comparable to the electrical conductivity of copper.

There are special tables that provide markings and descriptions of all bronze alloys produced by industry. However, even without referring to such tables, you can determine the type and chemical composition if you know how its labeling is deciphered.

By simple labeling you can find out their composition. Its characteristic feature in the designation is the letters “Br”, which means “Bronze ”.

They are then followed by letters indicating, in addition to copper, the presence of the corresponding components. These letter designations established by regulatory documents are as follows: A - aluminum, B - beryllium, K - silicon, F - iron, N - nickel, Mts - manganese, Mg - magnesium, C - lead, O - tin, T - titanium, F - phosphorus, C - zinc.

After the letter designations, there are numbers separated by hyphens indicating the percentage of each component (after copper). Designations are also used in which after each letter the percentage of a particular component is indicated. To find out the copper content, you need to subtract the percentage of all components from 100%.

Here are examples of markings and their interpretations: BrO5Ts6S5 - a bronze alloy in which the tin content is 5%, zinc - 6%, lead - 5%, copper - 84%; BrO3Ts8S4N1 - tin content - 3%, zinc - 8%, lead - 4%, nickel - 1%, copper - 84%; BrO10F1 - tin content - 10%, phosphorus - 1%, copper - 89%; BrB2 - beryllium content - 2%, copper - 98%; BrAZhMts10−3−1.5 - aluminum content - 10%, iron - 3%, manganese - 1.5%, copper - 85.5%; BrAZHN10−4−4 - aluminum content - 10%, iron - 4%, nickel - 4%, copper - 82%.

Due to its diverse properties, this metal finds wide application in various fields. The following products are made from it:

decorative elements (lamps, figurines, candlesticks, ashtrays, grilles, railing decorations and others);
various accessories (locks, handles, overhead hinges, taps, mixers and other plumbing fixtures);
parts of machines and mechanisms (bushings, seals, gears, bearings, parts of equipment operating under water);
parts for high-precision equipment, navigation devices, car circuits;
numerous fittings (bends, angles, adapters, couplings, tees, etc.);
a small amount of jewelry.

Bronze is widely used in rocketry and mechanical engineering, aviation and shipbuilding . Highly artistic objects for theaters, halls and palaces are made from it, monuments and sculptures are cast.

Thanks to the development of metallurgy, this metal is acquiring new and unusual properties that were inaccessible to blacksmiths and metallurgists of the past. Invented by the ancients, the alloy continues to faithfully serve humanity and progress for many, many centuries.

Source: https://tokar.guru/metally/splavy/bronza-sostav-splava-svoystva-i-primenenie.html

Bronze - composition, properties and characteristics of the alloy

Bronze owes its high popularity not only to its decorative characteristics, but also to a number of other properties. Meanwhile, few of those who use this metal can name the composition of bronze, but it is this that determines the characteristics of this copper alloy.

Foundry bronze BrZTs8S4N1 in ingots is used for the production of anti-friction parts

Main alloying additives

Bronze is a non-ferrous alloy based on copper, which determines most of its characteristics. Man began to produce and use bronze for various purposes since ancient times, as evidenced by the results of archaeological excavations. Initially, bronze was used, the composition of which was enriched with tin. Alloys of this type include, in particular, the so-called bell bronze (bells have been cast from it for many centuries).

In addition to bronzes containing tin, copper alloys that do not contain this chemical element are also actively used today. Instead of tin, the following are used as the main alloying additive in such copper alloys:

beryllium, which gives bronze increased strength;
silicon and zinc are elements that make the surface of a bronze product very resistant to abrasion and improve the fluidity of bronze, which is especially important for foundry operations;
lead, which gives bronze resistance to corrosion;
aluminum, which gives bronze decent anti-friction properties and high corrosion resistance.

The question about what metal is necessarily present in any bronze can be answered unequivocally: it is copper.

Chemical composition of various grades of bronze (click to enlarge)

In addition to division by chemical composition, there is a classification of bronze alloys according to processing technology:

deformable (used for the production of products that are processed by plastic deformation);
foundry (products from them are produced by casting).

Modern industry produces many grades of bronze, differing in their chemical composition and, accordingly, characteristics and scope of application. Many experienced craftsmen can even determine by the color of bronze what type it belongs to.

However, not everyone can do this.

The surest and easiest way to obtain information about what is contained in a certain brand of bronze and what type it is is to decipher the marking, which includes both alphabetic and digital designations.

Guitar strings: on the left from ordinary tin bronze (20% tin), on the right from phosphorus (7.7% tin, 0.3% phosphorus)

All grades of bronze alloys produced by modern enterprises in strict accordance with the requirements of regulatory documents (GOSTs) are listed in special tables, from which you can obtain information not only about the chemical composition of a certain grade of alloy, but also about its areas of application and characteristics. However, even without using such tables, you can determine the type of alloy and its chemical composition if you know the principle by which its designation is formed.

Mechanical properties and applicability of tin bronzes (k - chill casting, p - sand casting)

You can understand that this is bronze, a copper alloy, by the first letters “Br” present in the marking. After them, letters are placed, by which you can find out what other metals, besides copper, are contained in the chemical composition of this alloy. The regulatory document establishes the following rules for designating the chemical elements present in bronze:

Designation of additives in bronze composition

Typically, the marking of bronze of any brand does not indicate the amount of copper contained in its chemical composition. In this case, the numbers present in the designation indicate the quantitative content (in whole fractions of a percent) of the remaining elements.

Accordingly, the amount of copper contained in bronze of a certain brand is calculated as the difference between 100% of the total composition and the amount of additives. For example, bronze grade Br AZh 9-4 contains 9% iron and 4% aluminum, the remaining 87% is copper.

Bronze metal products are produced in the form of tape, wire, pipes, bushings, plates and rods

The amount of pure copper contained in bronze affects not only the technological and operational characteristics of the product, but also the color of its surface.

Thus, products made from the most common brands of bronze alloys, which contain about 85% copper, are distinguished by a golden color. If the amount of copper is reduced to 50%, the result can be white bronze, very similar in color to silver.

If desired, gray and even black bronze can be obtained - this result can be achieved by reducing the amount of copper in the alloy to 35% or lower.

Many old bronze products, the surface of which is almost black, acquired this color not due to the use of an alloy of a certain composition for their production, but as a result of exposure to time and various external factors (fires, prolonged exposure to damp soil, etc.). In ancient times, technologies for the production of bronze simply could not exist, the composition of which is supplemented by rare earth metals, giving it a rich black color.

Brands and areas of their application

Naturally, various chemical elements are introduced into the composition of any bronze not aimlessly, but in order to improve its properties. Thus, the content of a metal such as tin in bronze affects its ductility. The more bronze contains this metal, the harder and, accordingly, more brittle the alloy becomes.

However, the most significant influence on the hardness and strength of bronze is exerted by a chemical element such as beryllium. Some brands of bronze alloys containing beryllium in their chemical composition surpass high-quality steels in their strength characteristics.

If beryllium bronze is subjected to a hardening procedure, it, along with high strength, acquires elasticity, which makes it possible to make springs, springs and membranes for various purposes from this material.

Properties and applications of beryllium bronzes (click to enlarge)

Bronze alloys, the chemical composition of which is enriched with aluminum, are used to produce products that must combine sufficiently high strength with exceptional corrosion resistance.

Due to the characteristics of bronze alloys of this type, products made from them are successfully used in the most unfavorable conditions (high humidity, exposure to sea water, etc.).

In cases where it is necessary to make a product from bronze, which during operation will be subject to significant impact and frictional loads, it is better to use alloys containing lead in their chemical composition. In particular, bearings used in mechanisms for various purposes are made from such bronze.

Features of tin-free aluminum bronzes

Bronze, which, in addition to copper, contains silicon and zinc, is characterized by increased fluidity in the molten state, so they are used primarily for the production of complex parts by casting. A distinctive property of bronzes of this type is that no sparks are formed during mechanical impact on the products that are made from them. This quality is very important in many cases.

A relatively new type of bronze, which was developed in connection with the development of the oil industry, is copper alloys, the composition of which is enriched with aluminum and nickel.

Such bronzes, characterized by exceptional corrosion resistance, are often called marine bronzes, because products made from them are able to retain all their original characteristics even after prolonged use in salty sea water.

It was possible to obtain such alloys, which are actively used for the production of elements of oil platforms installed on sea and ocean shelves, thanks to the development of the metallurgical industry.

Most brands of bronze alloys are not magnetic, which makes it possible to successfully use them for the production of electrical products.

How is bronze made?

Over the long period of existence of bronze production technology, only the tools and equipment have changed, but the essence has remained the same. As in ancient times, the raw material for producing this copper alloy can be a charge or bronze waste, and the flux, which prevents too intense oxidation of the metal in the molten state, is charcoal.

This centrifugal casting installation will allow the production of bronze blanks weighing up to 50 kg

The smelting process itself, as a result of which bronze is obtained, is performed in the following sequence.

The crucible with the feedstock is placed in a furnace preheated to the required temperature.
To prevent the metal from oxidizing too much after melting, crushed charcoal - flux - is added to it.
After the metal has completely melted and warmed up well, phosphorous copper is introduced into its composition, which plays the role of an acid catalyst.
After some exposure in a heated state, alloying and binding elements (ligatures) are added to the molten metal, after which the resulting alloy is thoroughly mixed.
Before casting the molten metal, phosphorous copper is again added to it, which in this case is necessary to reduce the activity of oxidative processes.

At all stages of production, it is necessary to carefully monitor compliance with the correct temperature conditions in the furnace and the alloy itself. The amount of alloying and binding components added to the molten metal should also be controlled.

Natural and artificial patination

Many people have probably wondered why old bronze items look not like ordinary bronze, but like green-white bronze. This color appears due to the formation of a film called patina. The factor that influences the process of formation of such a film and the intensity of its occurrence is the interaction of the surface of the bronze product with the surrounding air and the components contained in it (exhaust gases, smoke, water vapor, etc.).

Patina, which can be of oxide or carbonate origin, is a protective film. Its presence makes the product look more noble (just look at the photo of old bronze objects to understand this).

Sugar bowl made of patinated bronze

Today, technologies have been developed that make it possible not only to remove a layer of patina from the surface of a bronze item, but also to perform artificial patination in order to give the bronze item some vintage appearance. This patination is performed using preparations containing sulfur. After they are applied to the surface of the product, it is heated to a certain temperature.

In addition to artificial patina, the surface of bronze products can be covered with a layer of varnish, gilding, chrome or nickel.

Source: http://met-all.org/cvetmet-splavy/bronza/bronza-sostav-splava-svojstva-marki-primenenie.html