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, current or heat passing 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 shine in reflected light, and each of the metals and alloys has its own special shade of shine or, as they say, color. For example, copper is pink-red, zinc is gray, tin is shiny white, etc.

Specific gravity - this 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/cm 3 .

Melting- the ability of metals and alloys to transform from solid to liquid is characterized by their melting point. Metals that have 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 linear and volumetric expansion coefficients. Linear expansion coefficient - the ratio of the increment in the length of a metal sample when heated to 1° to the original sample length. Volume expansion coefficient - the ratio of the increase in metal volume when heated to 1° to the original volume. The volumetric coefficient is taken equal to triple the coefficient of linear expansion. Different metals have different coefficients of linear expansion. For example, the linear expansion coefficient of steel is equal to 0,000012 , copper - 0,000017 , aluminum- 0,000023 . Knowing the coefficient of linear expansion of the metal, you can determine its elongation value:

Let's determine how much the steel pipeline length will be extended 5000 m when heated to 20°C :

5000 0.000012 20 = 1.2 m

Let's determine how much the copper pipeline length will extend 5000 m when heated to 20°C :

5000·0.000017·20= 1.7 m

Let's determine how much the aluminum pipeline length will extend 5000 m when heated to 20°C :

5000·0.000023·20=2.3 m

(In all three calculations, the coefficient of friction due to its own weight was not taken into account.) Based on the above calculations, non-ferrous metals expand to a greater extent when heated than steel, which must be taken into account during the welding process.

Thermal conductivity -the ability of metals and alloys to conduct heat. The greater the thermal conductivity, the faster heat spreads through the metal or alloy when heated. When cooled, metals and alloys with high thermal conductivity give off 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 accompanying heating is required.

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

Chemical properties of metals and alloys.

The chemical properties of metals and alloys mean their ability to combine with various substances, primarily 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 to air called the ability of the latter to resist the destructive effects of oxygen in the air.

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

Alkali resistance metals and alloys are called the ability to resist the destructive effects of alkalis. Alkalis are particularly destructive to 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 - a change in the properties of metals over time due to internal processes, usually occurring more slowly at room temperature and more intensely at elevated temperatures. The aging of steel is caused by the precipitation of carbides and nitrides along the grain boundaries, which leads to an increase in strength and a decrease in the ductility of steel. Elements that reduce the tendency of steel to age include aluminum and silicon, while elements that promote aging include nitrogen and carbon.

Mechanical properties of metals and alloys.

Rice. 1

The main mechanical properties of metals and alloys include

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

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

Hardness is the ability of a metal or alloy to resist the penetration of another harder body into it.

Rice. 2

In technology, the following methods for testing the hardness of metals and alloys are most widely used:

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

Rice. 3

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

Plasticity is the ability of a metal or alloy, without breaking, to change shape under load and to retain this shape after it is removed. Plasticity is characterized by relative elongation and relative contraction.

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

δ - relative elongation;

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

l 0 - initial length of the sample;

Where Ψ -relative narrowing at rupture;

F 0- 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 impact loads. Tests are carried out on a pendulum fire ( rice. 4). Before testing the pendulum 1 retracted to the angle of elevation α , in this position they are secured with a latch. Arrow 2 , mounted on the swing axis of the pendulum, is retracted until it stops 3 located at the zero scale division 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 backwards, the arrow 2 deviates from the zero division and, with the pendulum in a vertical position, indicates the value β - the largest angle of elevation of the pendulum after destruction of the sample. Angle difference α-β characterizes the work of a sample fracture.

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

A = P (N - h) kgf m

Where N - height of the pendulum before impact m

h -height of the pendulum after impact 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 deform plastically under the influence of a constant load (especially at elevated temperatures).

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

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

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

When testing samples for tensile strength, the ultimate strength is determined - σ in , yield strength (physical) - σ t , conventional (technical) yield strength - σ о,2 , true tensile strength - S to and relative elongation - δ .

Rice. 5

To understand the above values, consider the diagram presented in rice. 5. Vertical axis 0-P count the applied load R in kilograms (the higher the point along the axis, the greater the load), and along the horizontal axis the absolute elongation is Δ l .

Let's look at the sections of the diagram:

initial straight section 0-P pc, on which the proportionality between the elongation of the material and the load is maintained ( R pc-load at proportional limit)
sharp inflection point R't called load at upper yield strength
plot R' t - R t, parallel to the horizontal axis 0-Δ l (yield plateau), within which elongation of the sample occurs under constant load R t, called the load at the yield point
dot R in, indicating the greatest tensile force - load at ultimate strength
dot R k-force at the moment of sample destruction.

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

Where F 0- 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 lowest stress at which deformation of the test sample occurs without increasing the load (the load does not increase, but the sample elongates),

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

Proportionality limit σ pc- 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 tensile sample, defined as the ratio of the tensile force acting on the sample immediately before its rupture to the cross-sectional area of 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 refers to the ability of metals and alloys to be machined by cutting tools.

Malleability call the ability of metals and alloys to take the required shape under the influence of external forces, both in cold and hot states.

Fluidity call the ability of metals and alloys to fill foundry molds. Phosphorous cast iron has high fluidity.

Shrinkage is the ability of metals and alloys to reduce their volume upon cooling during solidification from a liquid state, cooling, sintering of compressed powders, or drying.

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

There is no unified system for marking non-ferrous metals and alloys based on them. In all cases, the alphanumeric system is adopted. Letters indicate that the alloys belong to a specific group, and 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 another - the number of alloying elements, and in the third they indicate the number of the alloy, which according to the state. the standard must meet a certain composition or properties.
Copper and its alloys
Technical copper is marked with the letter M, followed by numbers associated with the amount of impurities (indicating the degree of purity of the material). M3 grade copper contains more impurities than M000. The letters at the end of the mark mean: k - cathodic, b - oxygen-free, p - deoxidized. The high electrical conductivity of copper determines its primary use in electrical engineering as a conductor material. Copper deforms well, welds and solders well. Its disadvantage is poor machinability.
The main copper-based alloys include brass and bronze. In copper-based alloys, an alphanumeric system is adopted that characterizes the chemical composition of the alloy. Alloying elements are designated by a Russian letter corresponding to the initial letter of the element's 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 - N; Titan -T; Phosphorus - F; Chrome -X; Beryllium - B; Iron - F; Magnesium - Mg; Tin - O; Lead - C; Zinc - C.
The marking procedure for cast and wrought brasses 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 (tompak), with a content of 20-36% Zn - yellow. In practice, brasses with a zinc concentration exceeding 45% are rarely used. 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 brasses are marked according to GOST 15527-70.
The grade 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 are highly pressure-treatable. They are supplied in the form of pipes and tubes of various cross-sectional shapes, sheets, strips, tape, wire and rods of various profiles. Brass products with high internal stress (for example, cold-worked) are susceptible to cracking. When stored in air for a long time, longitudinal and transverse cracks form on them. To avoid this, before long-term storage it is necessary to relieve internal stress by performing low-temperature annealing at 200-300 C.
In multi-component brasses, after the letter L, a series of letters are written indicating which alloying elements, except zinc, are included in this brass. Then numbers follow through hyphens, the first of which characterizes the average copper content as a percentage, and the subsequent ones - each of the alloying elements in the same sequence as in the letter part of the brand. The order of letters and numbers is determined by the content of the corresponding element: first comes the element that has more, and then descending. The zinc content is determined by the difference from 100%.
Brasses are mainly used as a deformable, corrosion-resistant material. Sheets, pipes, rods, strips and some parts are made from them: nuts, screws, bushings, etc.
Casting brasses are marked in accordance with GOST 1711-30. At the beginning of the stamp they also write the letter L (brass), after which they write the letter C, which means zinc, and a number indicating its percentage content. In alloyed brasses, letters are additionally written corresponding to the entered alloying elements, and the numbers following them indicate the content of these elements as a percentage. The remainder missing up to 100% corresponds to the copper content. Casting brass is used for the manufacture of fittings and parts for shipbuilding, bushings, liners and bearings.
Bronze (alloys of copper with various elements, where zinc is not the main one). They, like brass, are divided into cast and wrought. All bronzes are marked with the letters Br, which is short for bronze.
In cast bronzes, after Br, letters are written followed by numbers, which symbolically indicate the elements introduced into the alloy (in accordance with Table 1), and the subsequent numbers indicate the content of these elements as a percentage. The rest (up to 100%) means copper. Sometimes in some brands of cast bronzes they write the letter “L” 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 pigs, ingots, wire rods, etc. (primary aluminum) according to GOST 11069-74 and in the form of a deformable semi-finished product (sheets, profiles, rods, etc.) according to 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, which can be used to determine the content of impurities in aluminum. Aluminum deforms well, but is difficult to cut. By rolling it you can make foil.

Aluminum-based alloys are divided into cast and wrought.
Casting alloys based on aluminum are marked according to GOST 1583-93. The grade reflects the main composition of the alloy. Most casting alloy grades begin with the letter A, which stands for aluminum alloy. Then letters and numbers are written that reflect 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 alloy number. The letter B at the beginning of the mark indicates that the alloy is high-strength.
The use of aluminum and alloys based on it is very diverse. Technical aluminum is used mainly 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 (using various casting methods), which require increased corrosion resistance in combination with low density, for example, some compressor pistons, levers and other parts.
Wrought alloys based on aluminum are also widely used in food and refrigeration technology for the manufacture of various parts by pressure processing, 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 using an alphanumeric system. However, there is no pattern in the labeling. The only peculiarity is the presence in all brands of the letter T, which indicates that they belong to titanium. The numbers in the brand indicate the conditional number of the alloy.
Technical titanium is marked: VT1-00; VT1-0. All other grades belong 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 disadvantages hinder their use in food and refrigeration equipment.

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

Magnesium-based alloys, like aluminum-based alloys, have a good combination of properties: low density, increased corrosion resistance, relatively high strength (especially specific strength) with good technological properties. Therefore, both simple and complex-shaped parts that require increased corrosion resistance are made from magnesium alloys: 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 equipment. Tin is used in the food industry as coatings for food containers (for example, tinning tin plates). Tin is marked in accordance with GOST 860-75. There are O1pch brands; O1; O2; O3; O4. The letter O stands for tin, and the numbers represent a conventional number. As the number increases, the amount of impurities increases. The letters pch at the end of the brand mean increased purity. In the food industry, tin of the O1 and O2 grades is most often used for tinning tin plates.
Alloys based on tin and lead, depending on their purpose, are divided into two large groups: babbits and solders.
Babbitts 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 babbitt, 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 babbitt), the letter C - lead babbitt, etc. It should be borne in mind that the brand of babbitt cannot determine its full chemical composition. In some cases, the tin content is not even indicated, for example in the BN brand, although it contains about 10%. There are also tin-free babbits (for example, lead-calcium), which are marked according to GOST 1209-78 and are not studied in this work.

Babbitts 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 characteristics: 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 low-melting (melting point tmelt ≤ 145 °C);

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

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

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

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.

Modern industry uses a huge amount of materials. Plastic and composites, graphite and other substances... But metal always remains relevant. Giant building structures are made from it, and 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, since, knowing it, you can select the most suitable type of material for a particular purpose. This article is dedicated to this topic.

General definition

Metals are simple substances that, under normal conditions, are characterized by the presence of several distinctive features: high thermal conductivity and electrical conductivity, 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 indicators. But there are also alloys that are their derivatives. What is it?

This is the name given to materials obtained from two or more substances by heating them above their melting point. Please note that there are metal and non-metal alloys. In the first case, the composition must contain at least 50% metal.

However, let’s not digress from the topic of the article. So, what is the classification of metal? In general, dividing it is quite simple:

Ferrous metals.
Non-ferrous metals.

The first category includes iron and all alloys based on it. All other metals are non-ferrous, as are their compounds. It is necessary to consider each category in more detail: despite the extremely boring general classification, in reality everything is much more complicated. And if you remember that there are also 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, classification is even more boring. This is the name (in jewelry) for the same silver, gold and platinum. However, enough about “high matters”. It's time to talk about more common and popular materials.

We will start with a review of different grades of steel, which is precisely a 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: chemical composition and production methods, the presence or absence of harmful impurities, as well as structure. However, the most important feature is the chemical composition, as it affects the grade and name of the steel.

Carbon varieties

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

Structural carbon steels

Most often they are 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 (σB, σ0.2, δ, ψ, KCU, HB, HRC). There are two types:

Ordinary.
High quality.

As you might guess, the first ones are used for the construction of various engineering structures. High-quality ones are used exclusively for the production of reliable tools used in mechanical engineering and other industries.

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

Tool carbon steels

Their field is precision engineering, the manufacture of instruments for the scientific field and medicine, as well as other industrial sectors that require increased strength and precision. Their carbon content can range 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 for materials that, in addition to natural impurities, contain a significant amount of artificially added alloying additives. These include chromium, nickel, molybdenum. In addition, alloy steels may also contain manganese and silicon, the content of which most often does not exceed 0.8-1.2%.

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

Steels with low additive content. In total there are no more than 2.5%.
Alloyed. They contain additives from 2.5 to 10%.
Materials with a high content of additives (more than 10%).

These types are also divided into subtypes, 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 viscosity. In addition, they are highly resistant to extremely low temperatures. They are used to make bridges, airplanes, rockets, and tools for high-precision industry.

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 and high-precision measuring instruments and tools. In particular, metal turning tools are made from this material, the classification of which directly depends on the steel: its grade is necessarily imprinted on the product.
They are also used to make dies for cold and hot rolling.

special purpose

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

Construction steels

Steels with medium carbon content. They are used to produce a wide range of various building materials. In particular, they are used to make profiles (shaped and sheet), pipes, angles, etc. Obviously, 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 this or that type of rolled product can be manufactured according to the customer’s individual requirements.

Reinforcing steels

As you probably guessed, their scope of application 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 or steel with a low content of alloying additives. There are two types:

Hot rolled.
Thermally and mechanically strengthened.

Boiler rooms steel

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

Automatic steels

This is the name for materials that can be processed well by cutting them. They also have high machinability. All this makes such steel an ideal material for automated production lines, of which there are more and more every year.

Bearing steels

These types, by their type, belong to the structural varieties, but their composition makes them similar to the instrumental ones. They are distinguished by high strength characteristics and great resistance to wear (abrasion).

We examined the basic properties and classification of metals of this class. Next in line is the 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 C content 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 cast iron has no additives, it is called unalloyed. Otherwise - doped.

Classification by purpose

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

Classification by type 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: when broken it is white and shiny, characterized by the highest hardness, but at the same time it is extremely fragile and can be machined with great difficulty.
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 characteristics 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, quite wear-resistant, easy to process.

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-pearlite and ferrite.

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

If it is represented by plates and “petals”, then it belongs to the lamellar variety.
If the material contains inclusions that resemble worms in appearance, then we are talking about vermicular graphite.
Accordingly, various flat, uneven inclusions indicate that this is a flocculent 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 it is ordinary gray cast iron (SG).
By analogy with the name “additives,” the presence of vermicular particles characterizes vermicular material (CVG).
Malleable cast iron (DC) contains flake-like inclusions.
The spherical “filler” characterizes high-strength cast iron (DC).

We have presented to your attention 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, differing greatly in their structure and physical properties. It would seem that cast iron is an ordinary and widespread 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, every year millions of tons of a wide variety of materials go into landfills. Are they really being sent en masse to be melted down without undergoing any sorting or screening? Of course not. There are nine categories in total:

3A. Standard ferrous metal waste, including large and especially large pieces. The weight of each fragment is at least 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. Cast iron scrap, dimensional. The weight of each piece is at least half a kilogram, but not more than 20 kg.
19A. Similar to the previous class, but the waste is oversized. In addition, some phosphorus content in the material is allowed.
20A. Cast iron scrap, the most oversized category. Pieces weighing five tons 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 quite similar.
22A. And again, oversized cast iron scrap. The difference is that in this case, the category of waste includes used and discarded plumbing equipment.
Mix. Mixed scrap. Important! The following types of contents are not allowed: metal wire, as well as galvanized parts.
Galvanization. As the name implies, this includes all scrap that contains 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 given to all other elements that have a metallic atomic structure, but do not belong to iron and its derivatives. In English-language literature you can find the term “non-iron metal”, which is a synonymous concept. What is the classification of non-ferrous metals?

There are the following groups, the division of which is based on several criteria at once: light and heavy, noble, scattered and refractory, radioactive and rare-earth varieties. Many of the non-ferrous metals generally belong to the category of rare, since their total quantity 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 electrical conductivity. In addition, they are in demand in the military, space and aviation industries, where maximum strength is required with a relatively low weight.

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 later.

Aluminum and alloys based on it

Aluminum, the “winged metal”. There are three types (depending on the degree of chemical purity):

Highest standard (special purity) (99.999%).
High purity.
Technical test.

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

Alloys

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

Duralumins.
Aviali.

Duralumin are alloys to which copper and magnesium are added. In addition, there are materials where copper and magnesium are used as additives. Alloys 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

Today they distinguish (pure substance content 97.97%) and especially pure, vacuum (99.99%). Unlike other non-ferrous metals, the mechanical and chemical properties of copper are extremely strongly influenced 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 thousands of years:

Brass. This is the name of the compound of copper and zinc.
Bronze. A copper alloy that no longer contains zinc, but tin. However, there are also bronzes that contain up to ten additives.

Titanium

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

Titanium alloys

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

Actually, we have fully reviewed 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 main element and a small amount of impurities of other elements. For example, technically 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 some simple metal (alloy base) with other metals or non-metals. For example, brass is an alloy of copper and zinc. Here the base 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 predominates in the alloy, there are also alloying components introduced into the alloy to obtain the required properties. Thus, 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 (ternary), etc. In addition to the main and alloying components, the alloy contains impurities of other elements.

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

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

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

At the present stage of technological development, along with an increase in the number of alloys and the complication of their composition, metals of special purity are becoming of great importance. The content of the main component in such metals ranges from 99.999 to 99.999999999%
and more. Metals of special purity are needed in rocket science, nuclear, electronics 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 are formed when they do not dissolve in each other in the solid state and do not enter into chemical interaction. Alloys are mechanical mixtures (for example, lead - antimony, tin - zinc) are heterogeneous in their 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 determined as the arithmetic average of the properties of both components.

2) Solid solutions characterized by the formation of a common spatial crystal lattice by atoms of the main solvent metal and atoms of the soluble element.
The structure of such alloys consists of homogeneous crystalline grains, like pure metal. There are substitutional 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 the properties of the constituent components. For example, the hardness and electrical resistance of solid solutions is much higher than that of pure components. Due to their high ductility, they lend themselves well to forging and other types of forming. 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, 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 fused components. The alloy composition of a chemical compound is expressed by its chemical formula. These alloys usually have high electrical resistance, high hardness, and low ductility. Thus, the chemical compound of iron and carbon - cementite (Fe 3 C) is 10 times harder than pure iron.

Metals have been used by humans for many millennia. The defining eras of human development are named after the names of metals: the Bronze Age, the Iron Age, the Age of Cast Iron, etc. Not a single metal product around us consists of 100% iron, copper, gold or other metal. Each contains additives deliberately introduced by a person and harmful impurities introduced 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), purposefully obtained 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 having the largest mass fraction is called the base.

Properties of alloys

The properties possessed by metal alloys are divided into:

To quantitatively express 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 from 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 devices. Steels have a wide range of properties. The common ones are strength and elasticity. The 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 production of frames for large machine tools and technological equipment, bases for work tables, and in the casting of fences, gratings, and decorative 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 and having pronounced magnetic properties are called ferrites. They are used in the production of transformers and inductors.

Copper-based metal alloys containing from 5 to 45% zinc are commonly called brasses. Brass is slightly 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 deliberately obtained by our ancestors several thousand years ago. Bronze is much stronger than both tin and copper and is second 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 aluminum-based materials, which contain silicon, magnesium or copper, are characterized by low specific gravity and high machinability. They are used in the engine, aerospace, and electrical component and appliance industries.

Zinc alloys

Zinc-based alloys have 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 affordable metal; it is difficult to produce and difficult to process. These shortcomings are compensated for by the 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 increases strength and heat resistance. To improve wear resistance, nitrogen is added to the material or 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 was rightly called the century of aluminum.

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

Aluminum alloys are divided into:

1. - Foundry (with silicon). Used to produce conventional castings.
  - For injection molding (with manganese).
  - Increased strength, with the ability to self-harden (with copper).

Main advantages of aluminum compounds:

1. - Availability.
  - Low specific gravity.
  - Durability.
  - Cold resistance.
  - Good machinability.
  - Electrical conductivity.

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

Another area of application is the production of weapons. Aluminum-based substances do not spark under strong friction and collisions. 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 magnetizability make them ideal for the production of housings for various radio and communications devices, computers and smartphones.

The presence of even a small proportion of iron significantly increases the strength of the material, but also reduces its corrosion resistance and ductility. A compromise on 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 alloy composition.

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

Copper alloys

Typically, copper alloys refer to various grades of brass. With a zinc content of 5-45%, brass is considered red (tombac), and with a zinc content of 20-35%, it is considered yellow.

Thanks 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 is 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 you add phosphorus instead of silicon, you get an excellent material for the production of membranes and leaf springs.

Hard alloys

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

Chromium, titanium, and 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 (mills, drills, taps, dies, cutters, etc.).
  - Measuring tools and equipment (rulers, squares, calipers; working surfaces of special evenness and stability).
  - Stamps, dies and punches.
  - Rolls of rolling mills and paper machines.
  - Mining equipment (crushers, cutters, excavator buckets).
  - Parts and assemblies of nuclear and chemical reactors.
  - Highly loaded parts of vehicles, industrial equipment and unique building structures, such as the Burj Tower in Dubai.

There are other areas of application of carbide substances.