Classification of metal and alloys

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

General definition

Metals are called simple substances, which under ordinary conditions are characterized by the presence of several distinctive features: high thermal conductivity and electrical current conductivity, as well as ductility. 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. Please note that there are metal and nonmetallic alloys. In the first case, at least 50% of the metal should 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, sharing it is quite simple:

1. Black metals.
2. Non-ferrous 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 recall that there are still precious metals ... And they are also different. However, the classification of precious metals is even simpler. There are eight in total: gold and silver, platinum, palladium, ruthenium, osmium, as well as rhodium and iridium. The most valuable are platinoids.

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

We begin with a review of different grades of steel, which is just the same as a derivative of the most common ferrous metal - iron.

What is steel?

This 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 sign is the chemical composition, since it affects the grade and name of the steel.

Carbon varieties

In these materials there are no alloying additives at all, but the technology of their manufacture allows for 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 manufacture of various tools. Of course, the classification of the metal is far from complete.

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 should have extremely high strength, which is determined by a whole cohort of tests certified by international agencies (σ, σ0,2, δ, ψ, KCU, HB, HRC). There are two types:

• Ordinary.
• Qualitative.

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

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 area is precision engineering, the manufacture of tools for the scientific field and medicine, as well as other industrial sectors that require increased strength and accuracy. In them, the 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

So called materials, which, in addition to natural impurities, contain a significant amount of artificially added alloying additives. These include chromium, nickel, molybdenum. In addition, in alloy steels there can also be 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:

• Low alloy steels. In total, there 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 engineering, construction of buildings and other structures, as well as in industry. If we compare them with carbon varieties, then such materials benefit in the ratio of strength characteristics, ductility and viscosity. In addition, they are highly resistant to extremely low temperatures. They make bridges, planes, rockets, tools for the high-precision industry.

Alloy Tool Steels

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

• Production of cutting, as well as high-precision measuring instruments and tools. In particular, metal turning tools 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 alloy steels

As the name implies, 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, 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 metal, etc.

Construction steels

Steel with an average carbon content. They are used to produce the widest range of various building materials. In particular, it is from them that profiles (shaped and sheet), pipes, angles, etc. are made. Obviously, 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 using mathematical models as an example, so in most cases this or that type of rental can be made according to individual customer requirements.

Reinforcing Steel

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

• Hot rolled.
• Thermally and mechanically hardened.

Boiler steel

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

Automatic steel

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

Bearing steel

These types by their type belong to structural varieties, but their composition is related to instrumental ones. They are distinguished by high strength characteristics and enormous resistance to wear (abrasion).

We have considered the basic properties and classification of metals of this class. Next in line is even more common and well-known 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 ranges from 2.14 to 6.67%. Cast iron, like steel, is distinguished by chemical composition, production methods and the quantitative volume of carbon contained in it, 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 - alloyed.

Intended classification

1. They are extreme, which are almost always used for subsequent processing into steel.
2. Foundry varieties used for casting products of various configurations and complexity.
3. Special, similar to steels.

Classification by type of chemical additives

Since the carbon content in various types of this material varies greatly, several of its varieties are also distinguished at once:

• 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, characterized by the highest hardness, but it is extremely fragile, it 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.
• Gray. It contains a lot of graphite. Durable, quite durable, lends itself well to processing.

We do not accidentally 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.

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”, then it refers to the plate variety.
• If the material has inclusions that in their appearance resemble worms, then we are talking about vermicular graphite.
• Accordingly, various flat, uneven inclusions indicate that you have a flaky variety in front of you.
• Spherical, hemispherical elements characterize a spherical shape.

But 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 inclusions, cast irons are divided into the following categories:

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

A brief classification and properties of metals that belong to the "black" category were presented to your attention. As you can see, despite the widespread misconception, they are very diverse, vary 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 just not similar to each other, like cast iron itself and sheet steel!

Waste - to income!

Is there any classification of ferrous scrap? Indeed, millions of tons of a wide variety of materials go to the dump every year. Are they really going to re-melting together without going through any sorting and sorting? Of course no. There are nine categories:

• 3A. Standard waste of ferrous metal, including overall, 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 involves a mixture of the two varieties described above.
• 17A. Scrap cast 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 is allowed in the material.
• 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 much the same.
• 22A. And again oversized cast iron scrap. The difference lies in the fact that in this case, the category of waste includes old and decommissioned plumbing equipment.
• Mix Mixed scrap. Important! Content of the following type is not allowed: steel ropes and metal wire, as well as galvanized parts.
• Galvanizing. As the name implies, this includes all the scrap, which includes galvanized fragments.

Such 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 metal atomic structure, but do not apply to iron and its derivatives. In English 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 separation of which is immediately 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 devices that must operate in an aggressive environment, friction, or, if necessary (sensors, for example), have a high degree of thermal conductivity or electrical current conductivity. In addition, they are in demand in the military, space and aviation sectors, where maximum strength is required with a relatively small mass.

Note that the classification of heavy metals stands apart. However, as such it does not exist, 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, "winged metal." There are three types of it (depending on the degree of chemical purity):

• Highest test (high purity) (99.999%).
• High purity.
• Technical sample.

The latter type is present on the market in the form of sheets, various profiles and wires with different cross sections. It is indicated in the trade as AD0 and AD1. Note that even in high-grade aluminum, interspersed 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 called alloys in 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 material science. The classification of metals on aluminum and its types does not end there.

Copper

To date, oxygen-free copper is distinguished (the content of the pure substance is 97.97%) and especially pure, vacuum (99.99%). Unlike other non-ferrous metals, even the smallest impurities of some additives influence the mechanical and chemical qualities of copper.

Alloys

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

• Brass. The so-called compound of copper and zinc.
• Bronze. , , . , , .

Titanium

. , , . , : 1-00 ( ≤ 0,10 %), 1-0 ( ≤ 0,30 %). ≤ 0,093 %, .

: . , : , . ( ).

Actually, we fully considered the classification of non-ferrous metals and alloys. We hope you find this article useful.