Classification of metal and alloys

In modern industry, a huge amount of materials are used. Plastic and composites, graphite and other substances ... But metal always remains relevant. It makes giant building structures, 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 this or that purpose. This article is devoted to this article.

General Definition

Metals are simple substances, which under ordinary conditions are characterized by the presence of several distinctive features: high thermal conductivity and conductivity of electric current, and also ductility. They are plastic. In the solid state, they are characterized by a crystalline structure at the atomic level, and therefore have high strength parameters. 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. Please note that alloys are metal and non-metallic. 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 matter of the article. So, what is the classification of metal? In general, it is quite easy to divide it:

1. Black metals.
2. Non-ferrous metals.

The first category includes iron and alloys based on it. All other metals are colored, however, like 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, too, are different. However, the classification of precious metals is even simpler. In total there are eight of them: gold and silver, platinum, palladium, ruthenium, osmium, and rhodium and iridium. The most valuable are the platinoids.

Actually, the classification of precious metals is even more boring. So called (in the jewelry business) are all the same silver, gold and platinum. However, it is enough about the "high matter". It's time to talk about more common and running materials.

We'll start with a review of different grades of steel, which is just the derivative of the most running black metal - iron.

What is steel?

It is an alloy of iron and some additives, which contains no more than 2.14% of atomic carbon. The classification of these materials is extremely extensive, and it takes into account: the chemical composition and production methods, 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 brand and name of the steel.

Carbon species

In these materials there are no alloying additives at all, but the technology of their manufacture allows a certain amount of other impurities (usually manganese). Since the content of these substances varies within the range of 0.8-1%, they have no effect on the strength, mechanical and chemical properties of the steel. This category is used in the construction and production of various tools. Of course, the classification of metal is far from over.

Structural carbon steel

Most often used for the erection of various designs of industrial, military or domestic use, but often they are used to produce tools and mechanisms. In this case, the carbon content should in no case exceed 0.5-0.6%. They must have an 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 it is easy to guess, the first go to the construction of various engineering structures. Qualitative structural steel is used exclusively for the production of reliable tools used in engineering and other industries and production.

As for these materials, corrosion of the metal is allowed on their surface. Classification of other types of steel provides for much more stringent requirements to them.

Tool carbon steel

Their sphere is the exact engineering, the manufacture of tools for the scientific field and medicine, as well as other industrial sectors in which increased strength and precision are required. In them, the carbon content can range from 0.7 to 1.5%. Such material must have a very high strength, be resistant to wear factors and extremely high temperatures.

Alloy Steel

So called materials in which, in addition to natural impurities, contains 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 usually does not exceed 0.8-1.2%.

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

• Steel with a low content of additives. In total they are no more than 2.5%.
• Alloyed. In them, the 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, are actively used in engineering, the erection of buildings and other structures, as well as in industry. If we compare them with carbon varieties, then such materials benefit from the ratio of strength characteristics, ductility and viscosity. In addition, they have high resistance to extremely low temperatures. Of these, bridges, airplanes, missiles, tools for high-precision industry are made.

Alloyed 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 produced from this material, the classification of which directly depends on steel: its brand is necessarily printed on the product.
• They also make stamps for cold and hot rolled products.

Alloyed special steels

As can be understood from the title, these materials have some specific characteristics. For example, there are heat-resistant and heat-resistant types, as well as all 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 smelting metals, etc.

Structural steel

Steels with an average carbon content. They are used for the production of the widest range of different building materials. In particular, profiles (shaped and sheet), pipes, corners, etc., are made of them. 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 the construction, all the characteristics are repeatedly calculated on the example of mathematical models, so that in most cases this or that type of rolled metal can be manufactured according to the individual requirements of the customer.

Reinforcing steel

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

• Hot rolled.
• Thermally and mechanically strengthened.

Boiler steels

Used for the production of boilers and cylinders, as well as other vessels and fittings, which will work under high pressure conditions under different temperature conditions. The thickness of the parts in this case can vary from 4 to 160 mm.

Automatic steel

The so-called materials that are well amenable to processing by cutting them. Also have high machinability. All this makes this steel an ideal material for automated production lines, which every year becomes more and more.

Bearing steel

These species are of their type refer to structural varieties, but their composition makes them related to the instrumental. They have high strength characteristics and great resistance to wear (abrasion).

We have considered the main properties and classification of metals of this class. Next in turn is an even more common and famous cast iron.

Cast iron: 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 varies from 2.14 to 6.67%. Cast iron, like steel, is distinguished in terms of chemical composition, production methods and the quantitative volume of carbon contained therein, as well as in applications in daily life and industry. If there are no additives in cast iron, it is called undoped. Otherwise - doped.

Classification according to purpose

1. There are limiting, which are almost always used for subsequent processing into steel.
2. Foundry varieties used for casting products of very different configuration and complexity.
3. Special, by analogy with steels.

Classification by types of chemical additives

Since the carbon content in various types of this material varies greatly, several types of it are also distinguished:

• White cast iron. Characterized by the fact that carbon in its structure is connected almost completely, being there in the composition of various carbides. It is very easy to distinguish: on the fracture it is white and shiny, characterized by the highest hardness, but at the same time extremely fragile, with great difficulty 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 in its structure a large amount of free graphite. In general, it combines the signs of both types. It is quite durable, but at the same time much easier to process, and with the fragility of things are much better.
• Gray. Contains a lot of graphite. Strong, sufficiently wear-resistant, it is easy to process.

We do not accidentally place emphasis 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 pearlitic, ferrite-pearlite and ferritic.

Graphite itself in each of these types of cast iron can be present in four different forms:

• If it is represented by plates and "petals", it refers to the lamellar variety.
• If the material has inclusions, which in their appearance resemble worms, then we are talking about vermicular graphite.
• Accordingly, various flat, uneven inclusions indicate that before you - a flaky variety.
• Spherical, hemispherical elements characterize a 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 iron is divided into the following categories:

• If there are inclusions of lamellar graphite in the material, then this is ordinary gray cast iron (MF).
• By analogy with the name of "additive", the presence of vermicular particles characterizes vermicular material (CVG).
• Flake-like inclusions contain malleable cast iron (CF).
• Spherical "filler" characterizes high-strength cast iron (HF).

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

Waste - in income!

Is there any classification of ferrous scrap? After all, millions of tons of the most diverse materials go to the dump every year. Are they going to the melting point in an inferior manner without going through any sorting and sorting? Of course no. Nine categories are distinguished:

• 3A. Standard waste of black metal, including oversized, extra-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 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 waste is oversized. In addition, some phosphorus content is allowed in the material.
• 20A. Cast iron scrap, the most oversized category. Allowed to pieces of five tons of weight. Typically, 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 an oversized cast-iron scrap. The difference lies in the fact that in this case, the waste category includes the old and decommissioned plumbing equipment.
• Mix Mixed scrap. Important! The following types of contents are not allowed: steel ropes and metal wire, as well as galvanized parts.
• Zinc coating. As is clear from the title, this includes all scrap, which contains galvanized fragments.

This was the classification of ferrous metals. And now we will discuss their color "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 refer to the iron and its derivatives. In the English-language literature one can find the term "non-ferrous metal", which is synonymous with the term. What is the classification of non-ferrous metals?

There are the following groups, the division of which goes right on several grounds: light and heavy, noble, scattered and refractory, radioactive and rare-earth species. 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 instruments that must operate under conditions of 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, aerospace and aviation industries, where maximum strength is required with a relatively small mass.

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

Aluminum and its alloys

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

• Higher sample (special purity) (99.999%).
• High purity.
• Technical test.

The latter type is present on the market in the form of sheets, a diverse profile and wire with a different cross-section. It is indicated in the trade as AD0 and AD1. 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.
• Airways.

Duralumin are alloys, in which copper and magnesium are added. In addition, there are materials where copper and magnesium are used as additives. Aviai also called alloys, but they contain much more additives. The main ones are magnesium and silicon, as well as iron, copper and even titanium.

In principle, this question takes material science in more detail. The classification of metals on aluminum and its types does not end there.

Copper

For today, copper is distinguished from anoxic (97.97% pure substance content) and especially clean, vacuum (99.99%). Unlike other non-ferrous metals, even the smallest admixtures of some additives influence the mechanical and chemical properties of copper very much.

Alloys

They are divided into two large groups. These materials, by the way, are 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 includes not zinc, but tin. However, there are also such bronzes, in which there are up to ten additives.

Titanium

This metal is rare and very expensive. It features low weight, incredible strength, low viscosity. Note that it is divided into several types: ВТ1-00 (in this material the amount of impurities is ≤ 0.10%), ВТ1-0 (additive volume ≤ 0.30%). If the total amount of foreign impurities is ≤ 0.093%, then such material in production is called iodide titanium.

Titanium alloys

Alloys of this material are divided into two types: deformable and linear. In addition, they distinguish between their specific subspecies: heat-resistant, increased plasticity. There are still hardened and not hardened varieties (depends on heat treatment).

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