Classification of aluminum alloys. Simultaneously with the reduction of iron, silicon, phosphorus, manganese and other impurities are reduced.

Classification of properties of metals and alloys

The properties of metals and alloys are divided into 4 main groups:

physical,
chemical,
mechanical,
technological.

Physical properties of metals and alloys.

The physical properties of metals and alloys include color, density (specific gravity), fusibility, thermal expansion, thermal conductivity, heat capacity, electrical conductivity, and their ability to be magnetized. These properties are called physical because they are found in phenomena that are not accompanied by a change in the chemical composition of the substance, i.e., metals and alloys remain unchanged in composition when heated, when current and heat pass through them, as well as when they are magnetized and melted. Many of these physical properties have established units of measurement by which the properties of the metal are judged.

Color.

Metals and alloys are not transparent. Even thin layers of metals and alloys are not capable of transmitting rays, but they have an external brilliance in reflected light, and each of the metals and alloys has its own special shade of brilliance or, as they say, color. For example, copper is rose red, zinc is grey, tin is brilliant white, and so on.

Specific gravity is the weight 1 cm 3 metal, alloy or any other substance in grams. For example, the specific gravity of pure iron is 7.88 g/cm3 .

Melting- the ability of metals and alloys to pass from a solid to a liquid state, characterized by a melting point. Metals with a high melting point are called refractory (tungsten, platinum, chromium, etc.). Metals with a low melting point are called fusible (tin, lead, etc.).

thermal expansion - the property of metals and alloys to increase in volume when heated, characterized by the coefficients of linear and volumetric expansion. Coefficient of linear expansion - the ratio of the increment in the length of a metal sample when heated to 1° to the original sample length. Coefficient of volumetric expansion - the ratio of the increment in the volume of the metal when heated to 1° to the original volume. The volumetric coefficient is taken equal to three times the coefficient of linear expansion. Different metals have different coefficients of linear expansion. For example, the coefficient of linear expansion of steel is equal to 0,000012 , copper - 0,000017 , aluminum- 0,000023 . Knowing the coefficient of linear expansion of the metal, it is possible to determine its elongation value:

determine how much the steel pipeline will lengthen 5000 m when heated to 20°С :

5000 0.000012 20 = 1.2 m

determine how long the copper pipeline will lengthen 5000 m when heated to 20°С :

5000 0.000017 20= 1.7 m

determine how long the aluminum pipeline will lengthen 5000 m when heated to 20°С :

5000 0.000023 20=2.3 m

(In all three cases, the coefficient of friction due to self-weight was not taken into account.) Based on the above calculations, non-ferrous metals expand more when heated than steel, which must be taken into account in the welding process.

Thermal conductivity - the ability of metals and alloys to conduct heat. The greater the thermal conductivity, the faster the heat spreads through the metal or alloy when heated. When cooled, metals and alloys with high thermal conductivity release heat faster. Thermal conductivity of red copper in 6 times higher than the thermal conductivity of iron. When welding metals and alloys with high thermal conductivity, preliminary and sometimes concomitant heating is required.

Heat capacity is the amount of heat required to raise the temperature of a unit of weight 1°. Specific heat capacity - the amount of heat in kcal(kilocalories) needed to heat 1 kg substances on 1°. Platinum and lead have a low specific heat capacity. The specific heat capacity of steel and cast iron is approximately 4 times higher than the specific heat capacity of lead.

Electrical conductivity - the ability of metals and alloys to conduct electric current. Copper, aluminum and their alloys have good electrical conductivity.

Magnetic properties - the ability of metals to be magnetized, which manifests itself in the fact that a magnetized metal attracts metals with magnetic properties.

Chemical properties of metals and alloys.

The chemical properties of metals and alloys are understood as their ability to enter into compounds with various substances, primarily with oxygen. The chemical properties of metals and alloys include:

resistance to corrosion in air,
acid resistance,
alkali resistance,
heat resistance.

Resistance of metals and alloys in air called the ability of the latter to withstand the destructive action of oxygen in the air.

acid resistance called the ability of metals and alloys to resist the destructive action of acids. For example, hydrochloric acid destroys aluminum and zinc, but lead does not; sulfuric acid destroys zinc and iron, but has almost no effect on lead, aluminum and copper.

alkali resistance metals and alloys is called the ability to withstand the destructive action of alkalis. Alkalis are especially strong destroy aluminum, tin and lead.

heat resistance called the ability of metals and alloys to resist destruction by oxygen when heated. To increase heat resistance, special impurities are introduced into the metal, such as chromium, vanadium, tungsten, etc.

Aging of metals - change in the properties of metals over time due to internal processes, usually proceeding slowly at room temperature and more intensively at elevated temperatures. The aging of steel is due to the release of carbides and nitrides along the grain boundaries, which leads to an increase in strength and a decrease in steel ductility. The elements that reduce the tendency to aging of steel are aluminum and silicon, and those that promote aging are nitrogen and carbon.

Mechanical properties of metals and alloys.

Rice. 1

The main mechanical properties of metals and alloys are

strength,
hardness,
elasticity,
plastic,
impact strength,
creep,
fatigue.

strength called the resistance of a metal or alloy to deformation and destruction under the action of mechanical loads. Loads can be compressive, tensile, twisting, shearing and bending ( rice. 1 ).

hardness called the ability of a metal or alloy to resist the penetration of another more solid body into it.

Rice. 2

In technology, the following methods for testing the hardness of metals and alloys have received the greatest use:

2,5 ; 5 And 10 mm- hardness test according to Brinell (rice. 2,a );
indentation into the material of a steel ball with a diameter 1.588 mm or diamond cone - hardness test according to Rockwell (rice. 2b )
indentation into the material of a regular tetrahedral diamond pyramid - test according to Vickers (rice. 2,in ).

Rice. 3

elasticity called the ability of a metal or alloy to change its original shape under the influence of an external load and restore it after the termination of the load ( rice. 3 ).

Plasticity called the ability of a metal or alloy, without collapsing, to change shape under the influence of a load and retain this shape after its removal. Plasticity is characterized by relative elongation and relative contraction.

Where Δ l \u003d l 1 -l 0 - absolute elongation of the sample at break;

δ - relative extension;

l 1 - the length of the sample at the time of rupture;

l 0 - the initial length of the sample;

Where Ψ -relative narrowing at break;

F0- initial cross-sectional area of the sample;

F- sample area after rupture

Fig 4

impact strength called the ability of a metal or alloy to resist the action of shock loads. Tests are carried out on a pendulum fire ( rice. 4). Before testing the pendulum 1 take to the angle of elevation α , in this position is fixed with a latch. Arrow 2 , fixed on the swing axis of the pendulum, is retracted to the stop 3 , located at the zero division of the scale 4 . The pendulum, released from the latch, falls, destroying the sample 5 and, (continuing to move then inertia, rises to the other side of the bed, at a certain angle β . When the pendulum moves back, the arrow 2 deviates from zero division and, with the pendulum in a vertical position, indicates the value β - the largest angle of elevation of the pendulum after the destruction of the sample. Angle difference α-β characterizes the work of the sample fracture.

To determine the impact strength, first calculate the work A, which is spent by the weight of the pendulum on the destruction of the sample

A \u003d P (H - h) kgf m

Where H - the height of the pendulum before it hits m

h - the height of the pendulum after impact in m

R - impact force.

Then the impact strength is determined

Where a n - impact strength in kgf m / cm 2

F - cross-sectional area of the sample in cm 2 .

Creep called the property of a metal or alloy to slowly and continuously plastically deform under a constant load (especially at elevated temperatures).

Fatigue called the gradual destruction of a metal or alloy with a large number of repetitively variable loads, and the ability to withstand these loads is called endurance.

Tensile testing of samples of metals and alloys carried out at low, normal and elevated temperatures. Tests at low temperatures are carried out in accordance with GOST 11150-65 0 -100°С and at the boiling point of technical liquid nitrogen. Tests at normal temperatures are carried out according to G OST 1497-61 at a temperature 20±10°С .

Tests at elevated temperatures are carried out according to GOST 9651-61 at temperatures up to 1200°C .

When testing specimens for tension, the ultimate strength is determined - σ in , yield strength (physical) - σ t , conditional yield strength (technical) - σ o,2 , true tear resistance - S to and elongation - δ .

Rice. 5

To assimilate the above values, consider the diagram presented in Fig. rice. 5. vertical axis 0-R calculate the applied load R in kilograms (the higher the point along the axis, the greater the load), and on the horizontal axis, the absolute elongation is Δ l .

Consider sections of the diagram:

initial straight section 0-R pc, which preserves the proportionality between the elongation of the material and the load ( R pc- load at the limit of proportionality)
kink point R't called the load at the upper yield point
plot R' t - R t, parallel to the horizontal axis 0-Δ l (yield area), within which elongation of the sample occurs at a constant load R t, which is called the load at the yield strength
dot R in, indicating the greatest tensile force - load at tensile strength
dot R to is the force at the moment of destruction of the sample.

Tensile strength in tension (temporary resistance) σ in- stress corresponding to the greatest load that preceded the destruction of the sample:

Where F0- the cross-sectional area of the sample before testing in mm 2

P in- the greatest tensile force in kgf .

Yield strength (physical) σ t- the smallest stress at which the deformation of the test sample occurs without increasing the load (the load does not increase, but the sample elongates),

Conditional yield strength (technical) σ o,2- stress at which the residual deformation of the sample reaches 0,2% :

proportional limit σ pts- conditional stress, at which the deviation from the linear relationship between stresses and strains reaches a certain degree, established by the technical conditions:

True tear resistance S to- stress in the neck of a stretched sample, defined as the ratio of the tensile force acting on the sample immediately before it breaks, to the cross-sectional area of the shape in the neck ( F ):

Technological properties of metals and alloys.

The technological properties of metals and alloys include:

machinability,
ductility,
fluidity,
shrinkage,
weldability,
hardenability, etc. .

Machinability called the ability of metals and alloys to be machined by a cutting tool.

Malleability called the ability of metals and alloys to take the necessary shape under the influence of external forces, both in a cold and in a hot state.

fluidity called the ability of metals and alloys to fill molds. Phosphorous cast iron has a high fluidity.

shrinkage called the ability of metals and alloys to reduce their volume during cooling when solidifying from a liquid state, cooling, sintering compressed powders or drying.

Non-ferrous metals include all metals, except for iron and alloys based on it - steels and cast irons, which are called ferrous. Alloys based on non-ferrous metals are mainly used as structural materials with special properties: corrosion-resistant, bearing (having a low coefficient of friction), heat- and heat-resistant, etc.

There is no single system for marking non-ferrous metals and alloys based on them. In all cases, an alphanumeric system is adopted. The letters indicate that the alloys belong to a certain group, and the numbers in different groups of materials have different meanings. In one case, they indicate the degree of purity of the metal (for pure metals), in the other, the number of alloying elements, and in the third, they indicate the number of the alloy, which according to the state. the standard must comply with a certain composition or properties.
Copper and its alloys
Technical copper is marked with the letter M, after which there are numbers associated with the amount of impurities (show the degree of purity of the material). Copper grade M3 contains more impurities than M000. The letters at the end of the brand mean: k - cathodic, b - oxygen-free, p - deoxidized. The high electrical conductivity of copper determines its predominant use in electrical engineering as a conductor material. Copper is well deformed, well welded and soldered. Its disadvantage is poor machinability.
The main copper-based alloys are brass and bronze. In alloys based on copper, an alphanumeric system is adopted that characterizes the chemical composition of the alloy. Alloying elements are designated by the Russian letter corresponding to the initial letter of the element name. Moreover, often these letters do not coincide with the designation of the same alloying elements when marking steel. Aluminum - A; Silicon - K; Manganese - Mts; Copper - M; Nickel - H; Titanium -T; Phosphorus - F; Chrome -X; Beryllium - B; Iron - F; Magnesium - Mg; Tin - O; Lead - C; Zinc - C.
The procedure for marking cast and wrought brass is different.
Brass is an alloy of copper and zinc (Zn from 5 to 45%). Brass with a content of 5 to 20% zinc is called red (tompac), with a content of 20-36% Zn - yellow. In practice, brasses are rarely used, in which the zinc concentration exceeds 45%. Usually brass is divided into:
- two-component brass or simple, consisting only of copper, zinc and, in small quantities, impurities;
- multi-component brass or special - in addition to copper and zinc, there are additional alloying elements.
Deformable brass are marked according to GOST 15527-70.
The brand of simple brass consists of the letter "L", indicating the type of alloy - brass, and a two-digit number characterizing the average copper content. For example, grade L80 is brass containing 80% Cu and 20% Zn. All two-component brasses work well with pressure. They are supplied in the form of pipes and tubes of various section shapes, sheets, strips, tapes, wires and bars of various profiles. Brass products with high internal stress (for example, hard-worked) are prone to cracking. During long-term storage in air, longitudinal and transverse cracks form on them. To avoid this, before long-term storage, it is necessary to remove the internal stress by low-temperature annealing at 200-300 C.
In multicomponent brasses, after the letter L, a number of letters are written indicating which alloying elements, in addition to zinc, are included in this brass. Then numbers follow through hyphens, the first of which characterizes the average copper content in percent, and the subsequent ones characterize each of the alloying elements in the same sequence as in the letter part of the brand. The order of letters and numbers is established according to the content of the corresponding element: first comes the element, which is more, and then descending. The zinc content is determined by the difference from 100%.
Brass is mainly used as a deformable corrosion-resistant material. Sheets, pipes, rods, strips and some parts are made from them: nuts, screws, bushings, etc.
Cast brass are marked in accordance with GOST 1711-30. At the beginning of the brand, they also write the letter L (brass), after which they write the letter C, which means zinc, and a number indicating its content as a percentage. In alloyed brass, letters are additionally written corresponding to the introduced alloying elements, and the numbers following them indicate the percentage of these elements. The rest, missing up to 100%, corresponds to the content of copper. Cast brass is used for the manufacture of fittings and parts for shipbuilding, bushings, liners and bearings.
Bronzes (copper alloys with various elements, where zinc is not the main one). They, like brass, are divided into foundry and wrought. Marking of all bronzes begins with the letters Br, which means bronze for short.
In foundry bronzes, after Br, letters are written followed by numbers, which symbolically designate the elements introduced into the alloy (in accordance with Table 1), and the following numbers indicate the percentage of these elements. The rest (up to 100%) is copper. Sometimes, in some brands of foundry bronzes, the letter “L” is written at the end, which means foundry.
Most bronzes have good casting properties. They are used for various shaped castings. Most often they are used as a corrosion-resistant and anti-friction material: fittings, rims, bushings, gears, valve seats, worm wheels, etc. All copper-based alloys have high cold resistance.
Aluminum and alloys based on it
Aluminum is produced in the form of ingots, ingots, wire rod, etc. (primary aluminum) in accordance with GOST 11069-74 and in the form of a deformable semi-finished product (sheets, profiles, rods, etc.) in accordance with GOST 4784-74. According to the degree of contamination, both aluminum is divided into aluminum of special purity, high purity and technical purity. Primary aluminum according to GOST 11069-74 is marked with the letter A and a number by which the content of impurities in aluminum can be determined. Aluminum is well deformed, but poorly processed by cutting. It can be rolled into foil.

Alloys based on aluminum are divided into cast and wrought.
Aluminum-based casting alloys are marked according to GOST 1583-93. The brand reflects the main composition of the alloy. Most grades of foundry alloys begin with the letter A, which stands for aluminum alloy. Then letters and numbers are written, reflecting the composition of the alloy. In some cases, aluminum alloys are marked with the letters AL (which means cast aluminum alloy) and a number indicating the number of the alloy. The letter B at the beginning of the grade indicates that the alloy is high-strength.
The use of aluminum and alloys based on it is very diverse. Technical aluminum is mainly used in electrical engineering as a conductor of electric current, as a substitute for copper. Aluminum-based casting alloys are widely used in the refrigeration and food industries in the manufacture of complex-shaped parts (by various casting methods) that require increased corrosion resistance in combination with low density, for example, some compressor pistons, levers and other parts.
Wrought aluminum-based alloys are also widely used in food and refrigeration technology for the manufacture of various parts by pressure treatment, which are also subject to increased requirements for corrosion resistance and density: various containers, rivets, etc. An important advantage of all aluminum-based alloys is their high cold resistance.
Titanium and alloys based on it
Titanium and alloys based on it are marked in accordance with GOST 19807-74 according to the alphanumeric system. However, there is no pattern in the labeling. The only feature is the presence of the letter T in all brands, which indicates belonging to titanium. The numbers in the grade indicate the conditional number of the alloy.
Technical titanium is marked: VT1-00; VT1-0. All other grades refer to titanium-based alloys (VT16, AT4, OT4, PT21, etc.). The main advantage of titanium and its alloys is a good combination of properties: relatively low density, high mechanical strength and very high corrosion resistance (in many aggressive environments). The main disadvantage is the high cost and scarcity. These shortcomings hinder their use in food and refrigeration engineering.

Titanium alloys are used in rocket, aviation, chemical engineering, shipbuilding and transport engineering. They can be used at elevated temperatures up to 500-550 degrees. Products from titanium alloys are made by pressure treatment, but can also be made by casting. The composition of cast alloys usually corresponds to the composition of the wrought alloys. At the end of the cast alloy brand is the letter L.
Magnesium and alloys based on it
Due to its unsatisfactory properties, technical magnesium is not used as a structural material. Alloys based on magnesium in accordance with the state. The standard is divided into foundry and deformable.
Cast magnesium alloys in accordance with GOST 2856-79 are marked with the letters ML and a number that indicates the conditional number of the alloy. Sometimes lowercase letters are written after the number: pch - high purity; it is general purpose. Wrought magnesium alloys are marked in accordance with GOST 14957-76 with the letters MA and a number indicating the conditional number of the alloy. Sometimes after the number there may be lowercase letters pch, which means high purity.

Magnesium-based alloys, like aluminum-based alloys, have a good combination of properties: low density, increased corrosion resistance, relatively high strength (especially specific) with good technological properties. Therefore, both simple and complex parts are made from magnesium alloys, which require increased corrosion resistance: necks, gasoline tanks, fittings, pump housings, brake wheel drums, trusses, steering wheels and many other products.
Tin, lead and alloys based on them
Lead in its pure form is practically not used in food and refrigeration engineering. Tin is used in the food industry as a coating for food packaging (for example, tinning of cans). Tin is marked in accordance with GOST 860-75. There are grades O1pch; O1; O2; O3; O4. The letter O stands for tin, and the numbers - a conditional number. As the number increases, the amount of impurities increases. The letters pch at the end of the brand mean - high purity. In the food industry, tin is most often used for tinning canning sheets of grades O1 and O2.
Alloys based on tin and lead, depending on the purpose, are divided into two large groups: babbits and solders.
Babbits are complex alloys based on tin and lead, which additionally contain antimony, copper and other additives. They are marked according to GOST 1320-74 with the letter B, which means babbit, and a number that shows the tin content as a percentage. Sometimes, in addition to the letter B, there may be another letter that indicates special additives. For example, the letter H denotes the addition of nickel (nickel babbit), the letter C denotes lead babbit, etc. It should be borne in mind that it is impossible to determine its complete chemical composition by the brand of babbit. In some cases, the tin content is not even indicated, for example, in the BN grade, although it contains about 10% here. There are also tinless babbits (for example, lead-calcium), which are marked according to GOST 1209-78 and are not studied in this work.

Babbits are the best antifriction material and are mainly used in plain bearings.
Solders in accordance with GOST 19248-73 are divided into groups according to many criteria: according to the method of melting, according to the melting temperature, according to the main component, etc. According to the melting temperature, they are divided into 5 groups:

1. Particularly fusible (melting point tmelt ≤ 145 °C);

2. Low-melting (melting point tmelt > 145 °С ≤ 450 °С);

3. Medium-melting (melting point tmelt > 450 °С ≤ 1100 °С);

4. High-melting (melting point tmelt > 1100 °С ≤ 1850 °С);

5. Refractory (melting point tmelt > 1850 °C).

The first two groups are used for low-temperature (soft) soldering, the rest - for high-temperature (hard) soldering. According to the main component, solders are divided into: gallium, bismuth, tin-lead, tin, cadmium, lead, zinc, aluminum, germanium, magnesium, silver, copper-zinc, copper, cobalt, nickel, manganese, gold, palladium, platinum, titanium , iron, zirconium, niobium, molybdenum, vanadium.

In modern industry, a huge amount of materials is used. Plastic and composites, graphite and other substances... But metal always remains relevant. Giant building structures are made from it, it is used to create a variety of machines and other equipment.

Therefore, the classification of metal plays an important role in industry and science, because, knowing it, you can choose the most suitable type of material for a particular purpose. This article is devoted to this topic.

General definition

Metals are called simple substances, which under normal conditions are characterized by the presence of several distinctive features: high thermal conductivity and conductivity of electric current, as well as malleability. Plastic. In the solid state, they are characterized by a crystalline structure at the atomic level, and therefore have high strength characteristics. But there are also alloys that are their derivatives. What it is?

So called materials obtained from two or more substances by heating them above the melting point. Note that there are metal and non-metal alloys. In the first case, at least 50% of the metal must be present in the composition.

However, we will not be distracted from the subject of the article. So, what is the classification of metal? In general, dividing it is quite simple:

Black metals.
Nonferrous metals.

The first category includes iron and all alloys based on it. All other metals are non-ferrous, however, as are their compounds. It is necessary to consider each category in more detail: despite the extremely boring general classification, in fact, everything is much more complicated. And if you remember that there are still precious metals ... And they are also different. However, the classification of precious metals is even simpler. There are eight of them in total: gold and silver, platinum, palladium, ruthenium, osmium, as well as rhodium and iridium. The most valuable are platinoids.

Actually, the classification is even more boring. So called (in jewelry) all the same silver, gold and platinum. However, enough about the "high matters". It's time to talk about more common and popular materials.

We will start with an overview of different grades of steel, which is just the same derivative of the most popular ferrous metal - iron.

What is steel?

Iron and some additives, which contains no more than 2.14% atomic carbon. The classification of these materials is extremely extensive, and it takes into account: the chemical composition and methods of production, the presence or absence of harmful impurities, as well as the structure. However, the most important feature is the chemical composition, as it affects the grade and name of the steel.

Carbon varieties

There are no alloying additives in these materials at all, but at the same time, their manufacturing technology allows a certain amount of other impurities (usually manganese). Since the content of these substances varies between 0.8-1%, they do not have any effect on the strength, mechanical and chemical properties of steel. This category is used in the construction and production of various tools. Of course, the classification of the metal is far from over.

Structural carbon steels

Most often used for the construction of various structures for industrial, military or domestic purposes, but they are often used to produce tools and mechanisms. In this case, the carbon content should in no case exceed 0.5-0.6%. They must have extremely high strength, which is determined by a whole cohort of tests certified by international agencies (σВ, σ0.2, δ, ψ, KCU, HB, HRC). There are two types:

Ordinary.
Quality.

As you might guess, the first go to the construction of various engineering structures. High-quality is used exclusively for the production of reliable tools used in mechanical engineering and others and production.

As for these materials, metal corrosion is allowed on their surface. The classification of steels of other types provides for much more stringent requirements for them.

Tool carbon steels

Their field is precision engineering, the manufacture of tools for the scientific and medical fields, as well as other industrial sectors that require increased strength and accuracy. In them, the carbon content can vary from 0.7 to 1.5%. Such a material must have very high strength, be resistant to wear factors and extremely high temperatures.

Alloy steels

This is the name of materials that, in addition to natural impurities, contain a significant amount of artificially added alloying additives. These include chromium, nickel, molybdenum. In addition, alloyed steels can also contain manganese and silicon, the content of which most often does not exceed 0.8-1.2%.

In this case, the classification of the metal implies their division into two types:

Steels with a low content of additives. In total, they are no more than 2.5%.
alloyed. In them, additives can be from 2.5 to 10%.
Materials with a high content of additives (more than 10%).

These types are also subdivided into subspecies, as in the previous case.

Alloy structural steel

Like all other varieties, they are actively used in mechanical engineering, the construction of buildings and other structures, as well as in industry. If we compare them with carbon varieties, then such materials win in terms of the ratio of strength characteristics, ductility and toughness. In addition, they are highly resistant to extreme low temperatures. Bridges, planes, rockets, tools for high-precision industry are made of them.

Alloy tool steels

In principle, the characteristics are very similar to the type discussed above. Can be used for the following purposes:

Production of cutting, as well as high-precision measuring instruments and tools. In particular, turning tools for metal are made from this material, the classification of which directly depends on steel: its brand is necessarily imprinted on the product.
They also make stamps for cold and hot rolling.

special purpose

As the name implies, these materials have some specific characteristics. For example, there are heat-resistant and heat-resistant types, as well as well-known stainless steel. Accordingly, the scope of their application includes the production of machines and tools that will work in particularly difficult conditions: turbines for engines, furnaces for metal smelting, etc.

Construction steels

Steel with medium carbon content. They are used for the production of the widest range of various building materials. In particular, it is from them that profiles (shaped and sheet), pipes, corners, etc. are made. It is obvious that when choosing a certain category of metal, special attention is paid to the strength characteristics of steel.

In addition, long before construction, all characteristics are repeatedly calculated using mathematical models, so that in most cases one or another type of rolled metal can be manufactured according to individual customer requirements.

Reinforcing steels

As you probably guessed, their scope is the reinforcement of blocks and finished structures made of reinforced concrete. They are produced in the form of rods or wire with a large diameter. The material is either carbon steel or low alloy steel. There are two types:

Hot rolled.
Thermally and mechanically hardened.

Boiler steels

They are used for the production of boilers and cylinders, as well as other vessels and fittings that have to work under conditions of high pressure at various temperature conditions. The thickness of the parts in this case can vary from 4 to 160 mm.

Automatic steels

So called materials that lend themselves well to processing by cutting them. They also have high machinability. All this makes such steel an ideal material for automated production lines, which are becoming more and more every year.

Bearing steels

By their type, these species belong to structural varieties, but their composition makes them related to the instrumental one. They are distinguished by high strength characteristics and great resistance to wear (abrasion).

We have considered the main properties and classification of metals of this class. Next in line is even more common and well-known cast iron.

Cast irons: classification and properties

This is the name of the material, which is an alloy of iron and carbon (as well as some other additives), and the content of C ranges from 2.14 to 6.67%. Cast iron, like steel, is distinguished by its chemical composition, production methods and the amount of carbon it contains, as well as by areas of application in everyday life and industry. If there are no additives in cast iron, it is called unalloyed. Otherwise, doped.

Classification by purpose

There are limiting, which are almost always used for subsequent processing into steel.
Foundry varieties used for casting products of various configurations and complexity.
Special, by analogy with steels.

Classification by types of chemical additives

White cast iron. It is characterized by the fact that carbon in its structure is almost completely bound, being there in the composition of various carbides. It is very easy to distinguish: at the break it is white and shiny, it is characterized by the highest hardness, but at the same time it is extremely fragile, with great difficulty it can be machined.
Half bleached. In the upper layers of the casting, it is indistinguishable from white cast iron, while its core is gray, containing a large amount of free graphite in its structure. In general, it combines the features of both types. It is quite durable, but at the same time it is much easier to process, and things are much better with fragility.
Grey. Contains a lot of graphite. Durable, fairly wear-resistant, well machined.

It is no coincidence that we focus on graphite. The fact is that the classification of metals and alloys in a particular case depends on its content and spatial structure. Depending on these characteristics, they are divided into pearlite, ferrite-pearlitic and ferritic.

The graphite itself in each of these can be present in four different forms:

If it is represented by plates and "petals", then it refers to the lamellar variety.
If the material contains inclusions that resemble worms in their appearance, then we are talking about vermicular graphite.
Accordingly, various flat, uneven inclusions indicate that in front of you is a flaky variety.
Spherical, hemispherical elements characterize the spherical shape.

But even in this case, the classification of metals and alloys is still incomplete! The fact is that these impurities, no matter how strange it may seem, directly affect the strength of the material. So, depending on the shape and spatial position of the inclusions, cast irons are divided into the following categories:

If the material contains inclusions of lamellar graphite, then this is ordinary gray cast iron (SC).
By analogy with the name "additives", the presence of vermicular particles characterizes the vermicular material (CVG).
Flaky inclusions contain ductile iron (CH).
Spherical "filler" characterizes high-strength cast iron (HF).

Your attention was presented with a brief classification and properties of metals that belong to the "black" category. As you can see, despite the widespread misconception, they are very diverse, varying greatly in their structure and physical properties. It would seem that cast iron is an ordinary and common material, but ... Even it has several completely different types, and some of them are as different from each other as cast iron itself and sheet steel!

Waste turns into income!

Is there any classification After all, millions of tons of a wide variety of materials go to the dump every year. Are they sent in droves to be melted down without going through any sorting and sorting? Of course no. There are nine categories in total:

3A. Standard waste of ferrous metal, including overall, especially large pieces. The weight of each fragment is not less than a kilogram. As a rule, the thickness of the pieces does not exceed six millimeters.
5A. In this case, the scrap is oversized. The thickness of the pieces is more than six millimeters.
12A. This category implies a mixture of the two varieties described above.
17A. Scrap iron, overall. The weight of each piece is not less than half a kilogram, but not more than 20 kg.
19A. Similar to the previous class, but oversized waste. In addition, some phosphorus content in the material is allowed.
20A. Cast iron scrap, the most oversized category. Pieces of five tons in weight are allowed. As a rule, this includes dismantled, decommissioned industrial and military equipment. As you can see, the classification and properties of metals in this category are pretty similar.
22A. And again, oversized cast iron scrap. The difference lies in the fact that in this case, the category of waste includes used and decommissioned plumbing equipment.
Mix. Mixed scrap. Important! The following types of content are not allowed: and metal wire, as well as galvanized parts.
Galvanized. As the name implies, this includes all scrap, which includes galvanized fragments.

This was the classification of ferrous metals. And now we will discuss their colored "colleagues", who play a huge role in all modern industry and production.

Non-ferrous metals

This is the name of all other elements that have a metallic atomic structure, but do not belong to iron and its derivatives. In the English-language literature, you can find the term "non-ferrous metal", which is a synonymous concept. What is the classification of non-ferrous metals?

There are the following groups, the division of which goes on several grounds at once: light and heavy, noble, scattered and refractory, radioactive and rare earth varieties. Many of the non-ferrous metals are generally classified as rare, since their total number on our planet is relatively small.

They are used for the production of parts and devices that must operate in an aggressive environment, friction, or, if necessary (sensors, for example), have a high degree of thermal conductivity or conductivity of electric current. In addition, they are in demand in the military, space and aviation industries, where maximum strength is required with a relatively small mass.

Note that the classification of heavy metals stands apart. However, it does not exist as such, but this group includes copper, nickel, cobalt, as well as zinc, cadmium, mercury and lead. Of these, only Cu and Zn are used on an industrial scale, which we will mention below.

Aluminum and alloys based on it

Aluminium, "winged metal". There are three types of it (depending on the degree of chemical purity):

The highest standard (special purity) (99.999%).
High purity.
Technical test.

The latter type is present on the market in the form of sheets, various profiles and wires with different sections. It is designated in trade as AD0 and AD1. Please note that even in high-grade aluminum, inclusions of Fe, Si, Gu, Mn, Zn are often present.

Alloys

What is the classification of non-ferrous metals in this case? In principle, nothing complicated. Exist:

Duralumin.
Avialy.

Duralumins are alloys to which copper and magnesium are added. In addition, there are materials where copper and magnesium are used as additives. Avials are also called alloys, but they contain many more additives. The main ones are magnesium and silicon, as well as iron, copper and even titanium.

In principle, this issue is considered in more detail by materials science. The classification of metals does not end with aluminum and its types.

Copper

To date, they distinguish (content of pure substance 97.97%) and extra pure, vacuum (99.99%). Unlike other non-ferrous metals, the mechanical and chemical properties of copper are extremely strongly affected by even the smallest impurities of some additives.

Alloys

They are divided into two large groups. These materials, by the way, have been known to mankind for more than one thousand years:

Brass. This is the name of the combination of copper and zinc.
Bronze. Copper alloy, which is no longer zinc, but tin. However, there are also bronzes in which there are up to ten additives.

Titanium

This metal is rare and very expensive. Differs in low weight, improbable durability, low viscosity. Note that it is divided into several types: VT1-00 (in this material, the amount of impurities ≤ 0.10%), VT1-0 (the amount of additives ≤ 0.30%). If the total amount of foreign impurities is ≤ 0.093%, then such material is called titanium iodide in production.

titanium alloys

Alloys of this material are divided into two types: deformable and linear. In addition, their special subspecies are distinguished: heat-resistant, increased plasticity. There are also hardened and non-hardened varieties (depending on heat treatment).

Actually, we have fully considered the classification of non-ferrous metals and alloys. We hope that the article was useful to you.

The concept of alloy, their classification and properties.

In engineering, all metallic materials are called metals. These include simple metals and complex metals - alloys.

Simple metals consist of one basic element and a small amount of impurities of other elements. For example, commercially pure copper contains from 0.1 to 1% impurities of lead, bismuth, antimony, iron and other elements.

Alloys- these are complex metals, representing a combination of a simple metal (alloy base) with other metals or non-metals. For example, brass is an alloy of copper and zinc. Here the basis of the alloy is copper.

A chemical element that is part of a metal or alloy is called a component. In addition to the main component that prevails in the alloy, there are also alloying components introduced into the composition of the alloy to obtain the required properties. So, to improve the mechanical properties and corrosion resistance of brass, aluminum, silicon, iron, manganese, tin, lead and other alloying components are added to it.

According to the number of components, alloys are divided into two-component (double), three-component (triple), etc. In addition to the main and alloying components, the alloy contains impurities of other elements.

Most alloys are obtained by fusing components in a liquid state. Other ways of preparing alloys: sintering, electrolysis, sublimation. In this case, the substances are called pseudoalloys.

The ability of metals to mutually dissolve creates good conditions for obtaining a large number of alloys with a wide variety of combinations of useful properties that simple metals do not have.

Alloys are superior to simple metals in strength, hardness, machinability, etc. That is why they are used in technology much more widely than simple metals. For example, iron is a soft metal, almost never used in its pure form. But the most widely used in technology are iron-carbon alloys - steels and cast irons.

At the present stage of development of technology, along with an increase in the number of alloys and the complication of their composition, metals of special purity are of great importance. The content of the main component in such metals ranges from 99.999 to 99.999999999%
and more. Metals of high purity are needed by rocket science, nuclear, electronic and other new branches of technology.

Depending on the nature of the interaction of the components, alloys are distinguished:

1) mechanical mixtures;

2) chemical compounds;

3) solid solutions.

1) mechanical mixture two components is formed when they in the solid state do not dissolve in each other and do not enter into chemical interaction. Alloys - mechanical mixtures (for example, lead - antimony, tin - zinc) are heterogeneous in structure and represent a mixture of crystals of these components. In this case, the crystals of each component in the alloy completely retain their individual properties. That is why the properties of such alloys (for example, electrical resistance, hardness, etc.) are defined as the arithmetic mean of the magnitude of the properties of both components.

2) Solid solutions are characterized by the formation of a common spatial crystal lattice by the atoms of the base metal-solvent and the atoms of the soluble element.
The structure of such alloys consists of homogeneous crystalline grains, like a pure metal. There are substitution solid solutions and interstitial solid solutions.

Such alloys include brass, copper-nickel, iron-chromium, etc.

Alloys - solid solutions are the most common. Their properties differ from those of the constituent components. For example, the hardness and electrical resistance of solid solutions are much higher than those of pure components. Due to their high ductility, they lend themselves well to forging and other types of pressure treatment. The casting properties and machinability of solid solutions are low.

3) Chemical compounds, like solid solutions, are homogeneous alloys. When they solidify, a completely new crystal lattice is formed, which is different from the lattices of the components that make up the alloy. Therefore, the properties of a chemical compound are independent and do not depend on the properties of the components. Chemical compounds are formed at a strictly defined quantitative ratio of the alloyed components. The alloy composition of a chemical compound is expressed by a chemical formula. These alloys usually have high electrical resistance, high hardness, and low ductility. So, the chemical compound of iron with carbon - cementite (Fe 3 C) is 10 times harder than pure iron.

Metals have been used by man for thousands of years. By the names of metals, the defining epochs of the development of mankind are named: the Bronze Age, the Iron Age, the Age of Cast Iron, etc. No metal product around us is 100% iron, copper, gold or any other metal. In any there are additives deliberately introduced by a person and harmful impurities that have fallen against the will of a person.

Absolutely pure metal can only be obtained in a space laboratory. All other metals in real life are alloys - solid compounds of two or more metals (and non-metals), obtained purposefully in the process of metallurgical production.

Classification

Metallurgists classify metal alloys according to several criteria:

Metals and alloys based on them have different physical and chemical characteristics.

The metal with the largest mass fraction is called the base.

Alloy properties

The properties that metal alloys possess are divided into:

To quantify these properties, special physical quantities and constants are introduced, such as the elastic limit, Hooke's modulus, viscosity coefficient, and others.

Main types of alloys

The most numerous types of metal alloys are made on the basis of iron. These are steels, cast irons and ferrites.

Steel is an iron-based substance containing no more than 2.4% carbon, used for the manufacture of parts and housings for industrial installations and household appliances, water, land and air transport, tools and fixtures. Steels have a wide range of properties. The common ones are strength and resilience. Individual characteristics of individual steel grades are determined by the composition of alloying additives introduced during smelting. Half of the periodic table is used as additives, both metals and non-metals. The most common of them are chromium, vanadium, nickel, boron, manganese, phosphorus.

If the carbon content is more than 2.4%, such a substance is called cast iron. Cast iron is more brittle than steel. They are used where it is necessary to withstand large static loads with small dynamic ones. Cast iron is used in the manufacture of frames for large machine tools and technological equipment, bases for work tables, in the casting of fences, gratings and decor items. In the 19th and early 20th centuries, cast iron was widely used in building structures. Cast iron bridges have survived to this day in England.

Substances with a high carbon content, having pronounced magnetic properties, are called ferrites. They are used in the manufacture of transformers and inductors.

Copper-based metal alloys containing from 5 to 45% zinc are commonly called brasses. Brass is not very susceptible to corrosion and is widely used as a structural material in mechanical engineering.

If you add tin to copper instead of zinc, you get bronze. This is perhaps the first alloy consciously obtained by our ancestors several millennia ago. Bronze is much stronger than both tin and copper and is inferior in strength only to well-forged steel.

Lead-based substances are widely used for soldering wires and pipes, as well as in electrochemical products, primarily batteries and accumulators.

Two-component materials based on aluminium, in which silicon, magnesium or copper are introduced, are characterized by low specific gravity and high machinability. They are used in the engine building, aerospace industry and the production of electrical components and household appliances.

zinc alloys

Zinc-based alloys feature low melting points, corrosion resistance and excellent machinability. They are used in mechanical engineering, the production of computers and household appliances, and in publishing. Good anti-friction properties allow the use of zinc alloys for bearing shells.

titanium alloys

Titanium is not the most accessible metal, it is difficult to manufacture and hard to process. These shortcomings are redeemed by its unique properties of titanium alloys: high strength, low specific gravity, resistance to high temperatures and aggressive environments. These materials are difficult to machine, but their properties can be improved by heat treatment.

Alloying with aluminum and small amounts of other metals improves strength and heat resistance. To improve wear resistance, nitrogen is added to the material or it is cemented.

Titanium-based metal alloys are used in the following areas:

1. - aerospace;
  - chemical;
  - atomic;
  - cryogenic;
  - shipbuilding;
  - prosthetics.

Aluminum alloys

If the first half of the 20th century was the century of steel, then the second half was rightfully called the century of aluminum.

It is difficult to name a branch of human activity in which products or parts made of this light metal would not be found.

Aluminum alloys are divided into:

1. - Foundry (with silicon). They are used to obtain ordinary castings.
  - For injection molding (with manganese).
  - Increased strength, having the ability to self-hardening (with copper).

The main advantages of aluminum compounds:

1. - Availability.
  - Small specific weight.
  - Durability.
  - Cold resistance.
  - Good machinability.
  - Electrical conductivity.

The main disadvantage of alloy materials is low heat resistance. Upon reaching 175°C, there is a sharp deterioration in mechanical properties.

Another area of application is the production of weapons. Aluminum-based substances do not spark when subjected to strong friction and impacts. They are used to produce lightweight armor for wheeled and flying military equipment.

Aluminum alloy materials are widely used in electrical engineering and electronics. High conductivity and very low magnetization make them ideal for the production of housings for various radio and communication devices, computers and smartphones.

The presence of even a small fraction of iron significantly increases the strength of the material, but also reduces its corrosion resistance and ductility. A compromise on the iron content is found depending on the requirements for the material. The negative effect of iron is compensated by adding metals such as cobalt, manganese or chromium to the ligature.

Magnesium-based materials compete with aluminum alloys, but due to their higher price they are used only in the most critical products.

copper alloys

Usually, copper alloys are understood to mean various grades of brass. With a zinc content of 5-45%, brass is considered red (tompac), and with a content of 20-35% - yellow.

Due to its excellent machinability by cutting, casting and stamping, brass is an ideal material for the manufacture of small parts that require high precision. The gears of many famous Swiss chronometers are made of brass.

Brass - a mixture of copper and zinc

A little-known alloy of copper and silicon is called silicon bronze. It is highly durable. According to some sources, the legendary Spartans forged their swords from silicon bronze. If we add phosphorus instead of silicon, we get an excellent material for the production of membranes and leaf springs.

Carbide

These are wear-resistant and high-hardness iron-based materials, which also retain their properties at high temperatures up to 1100 ° C.

Chromium, titanium, tungsten carbides are used as the main additive, nickel, cobalt, rubidium, ruthenium or molybdenum are auxiliary.

The main areas of application are:

1. - Cutting tools (milling cutters, drills, taps, dies, cutters, etc.).
  - Measuring tools and equipment (rulers, squares, calipers working surfaces of special evenness and stability).
  - Stamps, matrices and punches.
  - Rolls of rolling mills and paper machines.
  - Mining equipment (crushers, cutters, excavator buckets).
  - Details and components of nuclear and chemical reactors.
  - Highly loaded parts of vehicles, industrial equipment and unique building structures, such as, for example, the Burj-Dubai tower.

There are other areas of application of carbide materials.