What is cast iron: the composition of cast iron, what is the content of carbon and iron in it, the scope of use of the material

“Iron casting” has been known to mankind since time immemorial. Nowadays, it is widely used in many areas of the national economy and is called cast iron. And while the average person may not know about crankshafts, gear housings, wheel hubs, fittings, everyone knows about frying pans, cast iron pots, radiators, bathtubs, grates and other cast iron products.

The metallurgical industry produces various simple and special types of cast iron, each of which has its own scope of application.

What is

Cast iron is an iron-based alloy.
Belongs to the group of ferrous metals. Ferrous metals are iron, alloys based on it (steel, cast iron, ferroalloys), manganese. According to some classifications, chromium is included in the group.

In terms of composition, cast iron is a conglomerate of iron, carbon, plus other metals. The steel formula could contain the same basic components.

The difference between these alloys is the amount of carbon. If it is less than 2.14%, it is steel. More - cast iron.

Other components are alloys and impurities (sulfur, silicon, phosphorus, manganese).

Carbon in the structure of cast iron is represented by inclusions of graphite or cementite (iron carbide, formula – Fe3C).

You can distinguish cast iron from steel visually. Steel is lighter and shiny, cast iron is dark matte.

Advantages and disadvantages

Cast iron, like any material, has positive and negative sides.

The advantages of cast iron include:

• Carbon in cast iron can be in different states. Therefore, this material can be of two types (gray and white).
• Certain types of cast iron have increased strength, so cast iron is sometimes placed on the same line as steel.
• Cast iron can maintain temperature for quite a long time. That is, when heated, the heat is evenly distributed throughout the material and remains in it for a long time.
• In terms of environmental friendliness, cast iron is a clean material. Therefore, it is often used to make dishes in which food is subsequently prepared.
• Cast iron is resistant to acid-base conditions.
• Cast iron has good hygiene.
• The material has a fairly long service life. It has been noticed that the longer cast iron is used, the better its quality.
• Cast iron is a durable material.
• Cast iron is a harmless material. It is not capable of causing even slight harm to the body.

The disadvantages of cast iron include:

• Cast iron will rust if it is exposed to water for a short time.
• Cast iron is an expensive material. However, this minus is justified. Cast iron is very high quality, practical and reliable. Items made from it are also high quality and durable.
• Gray cast iron is characterized by low ductility.
• White cast iron is characterized by brittleness. It is mainly used for smelting.

Features of cast iron

Cast iron is an iron-carbon alloy, smelted using fuel from magnetic, red or brown iron ore, with the addition of special inorganic substances - fluxes.

Many people do not see the fundamental differences between steel and cast iron, mistakenly assuming that they are the same thing.

Both metallurgical products are alloys - they consist of several components, one of which is iron.

Cast iron is the raw material for steel production.

Technological properties:

• for steel – deformation (stamping, rolling, forging);
• for cast iron - foundries.

Presence of carbon:

• steel – 0.02 – 2.14%;
• cast iron - 2.14 - 6.67%.

External differences:

• cast iron is dark and matte;
• the steel is silvery and shiny.

Various physical characteristics

For cast iron:

• higher casting qualities;
• easy to cut;
• has less weight;
• lower melting point.

The disadvantages of cast iron include:

• low plasticity;
• fragility;
• weakly susceptible to forging and welding.

Cast iron has a low cost and is cheaper than steel.

Additives and impurities

All supplied cast iron is regulated by GOSTs in terms of its chemical composition and impurity content. Cast iron casting, in addition to iron, contains some “ingredients” that affect the final product and add certain features:

• carbons – increase the hardness of the alloy;
• silicon – improves casting qualities;
• manganese – gives strength;
• sulfur - “thickens” and limits the fluidity of cast iron.
• Phosphorus causes cracks to form when cold and reduces mechanical parameters.

In order to improve the starting material, cast iron is alloyed, that is, various alloying additives are introduced that change the physical and/or chemical properties.

Alloying additives:

• zirconium;
• aluminum;
• molybdenum;
• titanium;
• vanadium;
• copper;
• chromium.

Cast irons with a high content of silicon and manganese in their composition are classified as alloyed.

Story

The documented history of cast iron starts from the 1st millennium BC:

• Smelting was mastered by the Chinese and their neighbors.
• From the 5th century BC, the period of decorative iron casting began.
• 600 years later, coins appeared in China.

The appearance of the alloy in Europe dates back to the 14th century, in Russia – two hundred years later. Interest increased due to the suitability of cast iron as a material for cannons and cannonballs.

Eglinton Tournament Bridge (completed c. 1845), North Ayrshire, Scotland, built of cast iron

Since the time of Queen Victoria, fireplaces have become the most popular product in the “civil segment” among the British.

Cast iron coal iron
The heyday of the cast iron industry in Russia dates back to the 18th century:

• Bridges and rails appeared.
• Cast iron pots were invented in the Urals - the number one cookware for the Russian stove. Later they were supplemented with frying pans.
• By the end of the century, Russia had become the world leader in the production of cast iron.

The original bridge across the Tey from the north (finished in 1878)
The openwork products of Kasli craftsmen have gained world fame.

The method of molding for casting artistic castings of complex shapes, invented by the Kasli people, is still in demand by machine builders today.

Structure and composition

If we consider cast iron as a structural material, then it is a metal cavity with graphite inclusions. The structure of cast iron is mainly pearlite, ledeburite and ductile graphite. Moreover, for each type of cast iron these elements predominate in different proportions or are absent altogether.

According to the structure of cast iron there are:

• perlite,
• ferritic and
• ferritic-pearlitic.

Graphite is present in this material in one of the forms:

• Globular. Graphite takes on this shape when magnesium is added. The spherical shape of graphite is characteristic of high-strength cast irons.
• Plastic. Graphite is similar to the shape of petals. In this form, graphite is present in ordinary cast iron. This cast iron has increased ductility properties.
• Flaky. Graphite acquires this shape by annealing white cast iron. Graphite is found in flake form in malleable cast iron.
• Vermicular. The named form of graphite is found in gray cast iron. It was developed specifically to improve ductility and other properties.

Influence of impurities on material properties

The components that make up cast iron affect the quality of the alloy:

• sulfur helps reduce the refractoriness and fluidity of cast iron;
• phosphorus reduces strength, but makes it possible to vary the shape of finished products;
• silicon reduces the melting point of the metal and enhances its casting properties. In addition, this element makes it possible to obtain alloys of different colors: from pure white to ferritic;
• manganese gives cast iron strength and hardness, but reduces the casting and technological properties of the finished material;
• the introduction of titanium, aluminum, chromium, nickel or copper into the composition allows the production of alloyed alloys. They have high casting qualities and have proven good machinability. Production technology

Cast iron cast in the form of pigs
The source of raw materials for metallurgists is iron ores (rocks with a predominance of iron in the composition).

The ore is sent to processing plants, where part of the “empty” material is removed from the raw material.

The resulting material is transported to the metallurgical plant.

Here they are loaded into blast furnaces:

• Fuel is added - coke (a product of processing coal), limestone, briquetted coal dust.
• Melts at high temperatures.
• During the reduction process, iron with carbon embedded in its structure is obtained from oxides.

As a result of smelting, cast iron and slag are formed (a mixture of fuel ash, unused fluxes, and other products).

Ligatures are added if necessary. They determine the physical and chemical properties of the material.

Production is simple, but environmentally dirty.

The use of cast iron and products made from it in construction and other areas

Cast iron is the main metal of ferrous metallurgy. It is an alloy of iron and carbon. Cast iron may contain special additives that make its properties special. This cast iron has the characteristics of wear resistance, corrosion resistance, heat resistance, non-magneticity and others. We will talk about the properties, composition and areas of application of gray, white, malleable cast iron, as well as high-strength and granular cast iron below.

Classification

Cast iron is classified on several grounds:

• According to the dimensions and shape of graphite inclusions. Layered, spheroidal, vermicular, flakes.
• By type of carbon. Graphite, cementite.
• According to production technology. Grey, white, reworked.
• Based on the presence of additives. Ordinary and alloyed. Alloyed are alloys of cast iron with metals (molybdenum, nickel, chromium, titanium, etc.). Alloys with such metals give products ductility, resistance to wear, destruction, and corrosion.

Microstructure of white cast iron
Product characteristics are established at the production stage.

Varieties

There are white and gray cast iron.

• The carbon in white cast iron is in the form of iron carbide. If you break it, you can see a white tint. White cast iron is not used in its pure form. It is added to the process of producing malleable iron.
• At a fracture, gray cast iron has a silvery tint. This type of cast iron has a wide range of uses. It lends itself well to processing with cutters.

In addition, cast irons are high-strength, malleable and with special properties.

• High-strength cast iron is used to increase the strength of the product. The mechanical properties of such cast iron allow this to be done perfectly. High-strength cast iron is obtained from gray cast iron by adding magnesium to the mass.
• Ductile iron is a type of gray iron. The name does not mean that this cast iron is easily forged. It has increased plasticity properties. It is obtained by annealing white cast iron.
• There is also a distinction between half cast iron. Some of the carbon in it is in the form of graphite, and the remaining part is in the form of cementite.

Composition and types of white cast iron

White cast iron consists of the so-called cementite eutectic. In this regard, it is divided into three categories:

• Hypoeutectic. These are alloys in which carbon does not exceed 4.3% of the total composition. It is obtained after complete cooling. As a result, it acquires the characteristic structure of such elements as pearlite, secondary cementite and ledeburite.
• Eutectic. Their carbon content is 4.3%.
• Hypereutectic white cast iron. The content exceeds 4.35% and can reach 6.67%.

In addition to the above classification, it is divided into ordinary, bleached and alloyed.

The internal structure of white cast iron is an alloy of two elements: iron and carbon. Despite high-temperature production, it retains a fine-grained structure. Therefore, if you break a part made of such metal, a characteristic white color will be observed. In addition, in the structure of a hypoeutectic alloy, for example, hard grades, in addition to pearlite and secondary cementite, cementite is always present. Its percentage can approach 100%. This is typical for a eutectic metal. For the third type, the structure is a composition of eutectic (Ep) and primary cementite.

One of the varieties of such alloys is the so-called bleached cast iron. Its basis, that is, the core, is gray or high-strength cast iron. The surface layer contains a high percentage of elements such as ledeburite and perlite. The whitening effect up to 30 mm deep is achieved using the rapid cooling method. As a result, the surface layer is white, and then the casting consists of an ordinary gray alloy.

White cast iron structure

Depending on the percentage of alloyed additives, the following types of metal are distinguished:

• low-alloyed (they contain no more than 2.5% alloying elements);
• moderately alloyed (the percentage of such elements reaches 10%);
• highly alloyed (in them the amount of alloying additives exceeds 10%).

Quite common elements are used as alloying additives. The alloyed white cast iron obtained in this way acquires new, predetermined properties.

Properties of white cast iron

Any cast iron alloy, on the one hand, is very strong, but at the same time it is quite brittle. Therefore, the main positive properties of white cast iron include:

• High hardness. This greatly complicates the processing of parts, in particular cutting.
• Very high resistivity.
• Excellent wear resistance.
• Good resistance to increased heat.
• Sufficient corrosion resistance, including to various acids.

White cast irons, with a reduced percentage of carbon, are more resistant to high temperatures. This property is used to reduce the number of cracks in castings.

Appearance of white cast iron

The disadvantages include:

• Low casting properties. It has poor mold filling. During pouring, internal cracks may form.
• Increased fragility.
• Poor machinability of castings and parts made of white cast iron.
• Large shrinkage, which can reach 2%.
• Low impact resistance.

Another disadvantage is poor weldability. Problems in welding parts made of this material are caused by the fact that during welding, cracks form, both during heating and cooling.

Marking of white cast iron

To mark white cast iron, letters of the Russian alphabet and numbers are used. If it contains impurities, then the marking begins with the letter “H”. The composition of the available alloying additives can be determined by the following letters P, PL, PF, PVK. They indicate the presence of silicon. If the resulting metal has increased wear resistance, then its marking will begin with the letter “I”, for example ICHH, ICH. For example, the presence of the designation “Ш” in the marking means that the alloy structure contains spherical graphite.

The numbers indicate the amount of additional substances present in white cast iron.

Brand CHN20D2ХШ is deciphered as follows. This is a heat-resistant high-alloy metal. It contains the following elements: nickel - 20%, copper - 2%, chromium - 1%. The remaining elements are iron, carbon, and spherical graphite.

Main characteristics of steels

To determine the differences between cast iron and steel, you should consider each of these metals in more detail. Carbon is added to each of these alloys to obtain certain physical properties. It reduces the ductility and toughness of iron alloys, making them harder and stronger.

In steel, the C content does not exceed 2.14%. In addition to this, alloying components are added in the form of nickel, chromium, molybdenum, etc. Their amount should not exceed 53%.

This compound is plastic, making it easy to process. The quality improves during the hardening process. In addition, it has high thermal conductivity. The melting point varies between 1450°-1520°C.

Varieties

Before considering the difference between cast iron and steel and their differences, you should study their characteristics. Depending on the scope of application, steel connections are divided into the following types:

The structural type of connections has certain mechanical, physical and chemical properties. Depending on the amount of harmful impurities, the following subtypes are distinguished:

• ordinary (fluorine and sulfur content does not exceed 0.05%);
• high-quality (less than 0.035%);
• high quality (less than 0.025%);
• especially high quality (less than 0.015%).

Structural connections are used in construction and mechanical engineering. They are used to make various parts, mechanisms, and structures for mass use.

How to distinguish cast iron from steel

At scrap metal collection points, cast iron is accepted at a low price, since it is fragile, difficult to process, and removing harmful impurities from it is not an easy task. Experts shared with us tips on how to independently distinguish cast iron from other metals:

• by sound (if you hit steel with any object, the sound comes out very loud);
• by strength;
• on magnetic properties.

Cast iron can be easily distinguished from iron. Iron rusts quickly, it is light silver in color and ductile. But it is more difficult to distinguish cast iron from steel, due to their similar composition; they are externally similar to each other, but the characteristics of the alloys are different from each other.

Steel is easier to process and is not afraid of impacts. There is an opinion that a magnet will help distinguish cast iron from steel. This is correct to some extent, because the magnetic properties of the alloy depend on its composition.

What is cast iron?

The top 5 countries in terms of pig iron production include China, Japan, Russia, India and Korea. The high demand for the material is not only due to its domestic use. Cast iron is often used as a basis for the manufacture of steel alloys, which means that an extremely large volume of material is required.

There are 2 main types of cast iron - white and gray. The first is a material for the manufacture of malleable cast iron, and the second has wider areas of application both in industry and in everyday life.

You can see the features of alloy mining in the figure above. In the process of creating an alloy, the alloying additive plays an important role (as in the case of steel). There are hundreds of impurities, but the most popular are 4 elements.

Popular admixtures in the production of cast iron:

• sulfur. Reduces the level of refractoriness of a substance + reduces its fluidity in a liquid state;
• phosphorus. Reduces strength, but in return makes it possible to develop a product of a more complex shape;
• silicon. Reduces foundry temperature. The proportion of impurity changes the type of cast iron;
• manganese. Increases the strength of cast iron, but negatively affects the casting and technological properties of the alloy.

In addition to the above list, titanium, nickel, copper and aluminum are often added. Impurities affect both the chemical properties of cast iron and its physics and structure. In the latter case, there is a special classification - pearlitic, ferritic and pearlitic-ferritic varieties of cast iron.

The difference lies in the microstructure of graphite - spherical, plastic, flake or vermicular. The latter form was created specifically to improve the quality characteristics of gray cast iron.

Areas of application of cast iron:

• basis for crankshafts and engine blocks. It has also proven itself in the production of brake pads;
• one of the positive properties of cast iron is its resistance to temperatures, which allows the material to be used in the manufacture of equipment that is aimed at harsh climates with low temperatures;
• products in metallurgy are valued for adequate strength with high wear resistance;
• The household uses of cast iron are known to everyone - sinks, radiators, sinks, and so on. More expensive than regular steel, but much higher quality.

The material has even found its place among lovers of beauty. Cast iron is a classic material for works of art related in any way to metals in general. And forged gates are a sign of wealth to this day.

Differences from aluminum

A magnet can be used to distinguish cast iron not only from steel, but also from aluminum - a silvery-white light metal. This substance is paramagnetic, therefore it has external magnetic susceptibility (in the absence of an external magnetic field, the magnetic moments of atoms are non-zero).

The relative magnetic permeability of the metal is slightly greater than unity, and the magnetic field in it increases insignificantly. Accordingly, aluminum is magnetic, but very weakly. This is not visible visually, so it is generally accepted that it is not magnetic.

In addition to magnetic properties, metals have other differences: color, mass, density, hardness and flexibility. Therefore, you can distinguish them from each other in other ways.

Marking

In industry, types of cast iron are labeled as follows:

• pig iron
  - P1, P2;
• pig iron for castings
  - PL1, PL2,
• pig iron
  - PF1, PF2, PF3,
• conversion high-quality cast iron
  - PVK1, PVK2, PVK3;
• cast iron with lamellar graphite (gray cast iron
  - SCh (the numbers after the letters “SCh” indicate the value of tensile strength in kgf/mm2, 1 kgf/mm2 = 10 MPa);
• malleable cast iron
  - KCh (the numbers after the letters “KCh” indicate the value of tensile strength in kgf/mm2 and relative elongation in%);
• cast iron with nodular graphite for castings (high-strength cast iron)
  - HF (the numbers after the letters “HF” indicate the value of tensile strength in kgf/mm2 and relative elongation in %);
• anti-friction cast iron
  (gray - AChS, high-strength - AChV, malleable - AChK);
• alloyed cast iron with special properties
  - Ch (the letters after the letter "C" indicate alloying elements: X - chromium, C - silicon, G - manganese, N - nickel, D - copper, M - molybdenum, T - titanium, P - phosphorus, Yu - aluminum).

Areas of use

Cast iron is common in many areas.

• It is used for the production of parts in mechanical engineering. Engine blocks and crankshafts are mainly made from cast iron. The latter require advanced cast iron, to which special graphite additives are added. Due to the resistance of cast iron to friction, it is used to make excellent quality brake pads.
• Cast iron can operate smoothly even at extremely low temperatures. Therefore, it is often used in the production of machine parts that will have to work in harsh climatic conditions.
• Cast iron has proven itself well in the metallurgical field. It is valued for its relatively low price and excellent casting properties. Products made from cast iron are characterized by excellent strength and wear resistance.
• A large variety of plumbing products are made from cast iron. These include sinks, radiators, sinks and various pipes. Cast iron bathtubs and heating radiators are especially famous. Some of them still serve in apartments today, although they were purchased many years ago. Cast iron products retain their original appearance and do not require restoration.
• Thanks to its good casting properties, cast iron produces real works of art. It is often used in the manufacture of artistic products. For example, such as beautiful openwork gates or architectural monuments.

White cast iron

Carbon cementite is formed due to instantaneous cooling. Recognized by the whitish color of the fracture, hardness, and fragility. The alloy is unsuitable for machining by cutting. It is used for solid wear-resistant casting (rolling rolls, parts of mill and crushing mechanisms) and as a source of malleable types of cast iron.

Microstructure of white cast iron at 100x magnification

Grey

The basis of the structure is layered graphite, which imparts a grayish tint. It can be machined, but its strength and ductility are low.

Advantages: good anti-friction, damping properties, mini-sensitivity to voltage batteries, fluidity, minimum defects during shrinkage.

It is used as a material for castings of complex configurations with wall thicknesses up to 5 cm.

It is used to make rolling mills, flywheels, columns, frames, and sewer and water supplies (manholes, pipes, fittings).

Cast iron manhole cover

Malleable

The result of heat treatment of white cast iron with flake graphite. This structure ensures strength, ductility, good machinability of castings, and the absence of internal stress.

Thanks to this, the alloy has found application as a material for parts and elements operating under conditions of shock and vibration: pedestals for massive equipment, supports for highways, railway bridges, diesel engine crankshafts.

The Severn Bridge - the world's first cast iron bridge

Half-hearted

An intermediate material between the first two varieties is half-cast iron. The carbon it contains is presented in the form of graphite and carbide in approximately equal proportions. In addition, such an alloy may contain small amounts of lideburite (no more than 3%) and cementite (no more than 1%). The total carbon content of half cast iron ranges from 3.5 to 4.2%. This variety is used for the production of parts that are operated under conditions of constant friction. These include automobile brake pads, as well as rolls for grinding machines. To further increase wear resistance, all sorts of additives are added to the alloy.

High strength

This type of cast iron is obtained due to the formation of spherical graphite inclusions in the metal lattice. Because of this, the metal base of the crystal lattice weakens, and the alloy acquires improved mechanical properties. The formation of spherical graphite occurs due to the introduction of magnesium, yttrium, calcium and cerium into the material. High-strength cast iron is close in its parameters to high-carbon steel. It lends itself well to casting and can completely replace steel parts of mechanisms. Due to its high thermal conductivity, this material can be used for the manufacture of pipelines and heating devices.

Special

Alloys with additional characteristics obtained by alloying, annealing and cooling using special technology.

Divided into:

• ferroalloys;
• corrosion-, wear-, heat-resistant;
• antifriction;
• with electromagnetic properties;
• decorative.

The composition of alloys and technology are regulated by standards.

High-strength grades become the mechanism of turbines, crankshafts, tractor and automobile engines, gears, and rolling rolls.

Anti-friction grades are used for bearings, fuel pump bushings, valves, and piston rings for cars.

Fences, columns, fountains, and small plastic items are forged from decorative ones.

Cast iron fence

Peredelny

A semi-finished product, a source for processing into steel or creating castings. The percentage of phosphorus, silicon, sulfur, manganese components in the alloy is regulated by the industry standard.

Depending on the purpose and percentage of silicon, pig iron for steelmaking, foundry production, phosphorous, and high-strength are distinguished.

The latter type of alloy contains graphite beads and magnesium. Used for the production of parts operating under extreme loads (mechanical and thermal) in aggressive environments.

What is steel?

There is almost no tool/equipment in the world that does not contain steel. The material fits so tightly into the life of humanity that it is very problematic to imagine our existence without this alloy.

The first samples of the alloy were discovered in Turkey. The items are more than 3,700 years old, which means that steel items were popular even before our era. Wars of the past could not have happened without the use of steel weapons - cheap and durable. Industrial casting technology was developed in the early 19th century by Gentsman.

1) Structure and advantages of the alloy

China, Japan and India are considered the leaders in steel production. Russia is consistently among the top 5 countries in terms of production volumes, including. Taking into account the geography of leading producers, it is easy to guess that Asia is the leader in steel in the world.

Important: steel does not belong to pure chemical elements - it is a compound based on several.

A wide range of steel alloys with varying levels of strength, corrosion resistance and other unique characteristics is possible due to the material's "flexibility" in connection with other components.

Features of steel alloys:

• the mandatory presence of 2 components - carbon and iron. The first is responsible for viscosity, and the second is strength;
• With all the abundance of steel mining methods, completely pure variations of mining do not exist. Any alloy will have up to 1.2% silicon and up to 0.5% manganese. With minor inclusions, such impurities do not greatly affect the properties of the resulting alloy;
• To change the properties of the material, other metals are artificially introduced into the alloys in technologically specified proportions.

It is important to note that to change the characteristics of the alloy, sometimes it is enough to introduce only 5% of the alloying component. This diversity allows you to scale metal production at the owner’s discretion, based on demand or the level of competition within the local/global market.

2) Steel classification

The table below will tell you more about the distribution of steel alloys.

Thanks to adjustments to alloying inclusions + a specific manufacturing method, another 20 to 100 grades of material can be distinguished in each group.

3) Steel production + pricing

The table below will tell you about the methods for making steel.

After using one of the methods, the steel making process is not completed. The result of the work should be a material with a high margin of safety, and it will not be possible to achieve such results without additional processing methods.

The price of steel is as varied as the number of grades. For convenience, the exchanges use the term “standard steel” - from $230 per 1 ton of material. If we are talking about stainless steel grades, the cost can rise to $2,000 per 1,000 kg or more.

Manufacturing technologies

As you know, cast iron is produced in special blast furnaces. The main raw material for its production is iron ore. The manufacturing process consists of the reduction of iron ore oxides and the resulting production of another material - cast iron. For its production, fuels such as coke, thermoanthracite, and natural gas are used.

To produce one ton of pig iron, about 550 kilograms of coke and approximately a ton of water are required. The volume of ore loaded into the furnace will depend on the iron content in it. As a rule, ore is used, which contains at least 70% iron. The thing is that it is not economically feasible to use a lower concentration.

The first stage in the production of cast iron is its smelting. Ore is poured into the blast furnace, and then coking coal, which is necessary to pump and maintain the required temperature inside the furnace shaft. During combustion, these components take an active part in the ongoing chemical reactions as iron reducers.

Meanwhile, flux is immersed in the furnace, which acts as a catalyst. By accelerating the melting of rocks, it thereby supports the rapid release of iron. It is important to know that before loading into the furnace, the ore undergoes the necessary pre-treatment. It is crushed in a crushing plant because smaller particles melt faster. It is then washed to remove non-metal particles. Next, the raw material is fired, as a result of which sulfur and other foreign components are extracted from it.

At the second stage of production, natural gas is supplied through special burners into the filled and ready-to-use furnace. Coke is involved in heating the raw materials. Carbon is released, which combines with oxygen to form an oxide. It, in turn, promotes the recovery of iron from ore.

As the volume of gas in the furnace increases, the rate of the chemical reaction decreases. It may even stop completely when a certain gas ratio is reached. Carbon penetrates the alloy and combines with iron to form cast iron. Unmelted elements remain on the surface and are soon removed. Such waste is called slag. It is used to make other materials.

First stage of production

Iron smelting occurs as follows. First of all, ore is poured into the furnace, as well as coking coal grades, which serve to pump and maintain the required temperature inside the furnace shaft. In addition, during the combustion process, these products actively take part in the ongoing chemical reactions as iron reducers.

At the same time, flux is loaded into the furnace, serving as a catalyst. It helps the rocks melt faster, which promotes the rapid release of iron.

It is important to note that the ore undergoes special pre-treatment before loading into the furnace. It is crushed in a crushing plant (small particles melt faster). Afterwards it is washed to remove particles that do not contain metal. After which the raw material is fired, due to this, sulfur and other foreign elements are removed from it.

Second stage of production

Natural gas is supplied to the loaded and ready-to-use furnace through special burners. Coke heats the raw material. This releases carbon, which combines with oxygen to form an oxide. This oxide subsequently takes part in the reduction of iron from the ore. Note that as the amount of gas in the furnace increases, the rate of the chemical reaction decreases, and when a certain ratio is reached, it stops altogether.

Excess carbon penetrates the melt and combines with iron, ultimately forming cast iron. All those elements that have not melted end up on the surface and are eventually removed. This waste is called slag. It can also be used to produce other materials. The types of cast iron obtained in this way are called foundry and conversion.

What are the similarities and differences between steel and cast iron?

It is useful to know what the difference between materials is for housewives, because cast iron products are much more expensive than their steel counterparts. It will be a shame to overpay 3-5 times, and in the end, to get deceived by a persistent market trader.

1) Similarity/difference of basic characteristics

What cast iron and steel have in common is the material category. Both the first and second contain carbon and iron. This is where the common features of the alloys end. Even when adding the same amount of alloying elements, the resulting result in terms of characteristics will not be 100% or even 80% similar.

Now for the differences. To make it easier to understand, we will present the data in table form.

Already based on the information presented above, you can draw certain conclusions, even just by holding two samples of materials in your hands. The most important distinguishing feature at the composition level is the proportion of carbon. If the alloy contains 2.5% of this element, the alloy is considered cast iron, not steel.

Methods for determining steel and cast iron at home:

Industry challenges

Today, cast iron casting has dubious prospects. The fact is that due to high costs and large amounts of waste, industrialists are increasingly abandoning cast iron in favor of cheap substitutes. Thanks to the rapid development of science, it has long been possible to obtain higher quality materials at lower costs. Environmental protection plays a major role in this issue and does not accept the use of blast furnaces. It will take years, if not decades, to completely convert iron smelting to electric furnaces. Why so long? Because it is very expensive, and not every state can afford it. Therefore, all that remains is to wait until mass production of new alloys is established. Of course, it will not be possible to completely stop the industrial use of cast iron in the near future. But it is obvious that the scale of its production will fall every year. This trend began 5-7 years ago.

Advantages and disadvantages

At the household level, the main advantages of cast iron alloys are: non-toxicity, biocompatibility, hygiene, and heat resistance. Thanks to this, cast iron and other cookware are not destroyed by acid-base compounds (for example, when cooking borscht), are easy to clean, and remain warm for a long time.

For industrialists, other advantages come to the fore:

• A simple, economical way to obtain.
• Durability, preservation of consumer characteristics of products for decades.
• Possibility of producing a wide range.

Plus affordable prices for all products - from ingots to frying pans or a decorative bench.

Cast-iron pan

Disadvantages of the material:

• Fragility.
• Difficulty in welding.
• Vulnerability to corrosion.
• Heaviness of products.

Often, special conditions are required for transportation, assembly, and maintenance of products.

When welding, for example, the parts are heated in advance, the material and mode are selected. That is, they use gas installations, coated or carbon electrodes, and powdered wire.

Methods of welding cast iron products

To weld the material, specialists resort to the use of coated or carbon electrodes. In addition, flux-cored wire is used, as well as equipment for gas welding. If we consider the process of welding high-density cast iron products from a technological point of view, then we need to highlight three main areas:

1. Obtaining a high-quality weld in the material.
2. Producing a low-carbon weld.
3. Preparation of a weld consisting of alloys of non-ferrous metals.

When welding high-density cast iron products, an important task is to prevent the occurrence of hardened areas. To avoid this, preheat the parts that will be welded. Depending on the degree of heating, the following types of welding are distinguished:

• hot - with this welding mode, the products are preheated to a temperature of 600–650 degrees Celsius;
• semi-hot - a high-density product prepared for welding is heated to a temperature of 450 degrees Celsius;
• cold welding - performed without preheating.

The use of the first two modes of welding high-density cast iron should be resorted to in cases where the task is to obtain a high-density alloy in the weld material, which is close to the base material.

Hot welding. When this mode is performed, the cold part prepared for welding is heated to 650 degrees Celsius. This allows you to create conditions for uniform heating and slow cooling of parts after completion of work.

Semi-hot welding. When the connection of cast iron products is made by semi-hot welding, then to solve the problem of increasing graphitization, they resort to using the method of introducing graphitizing substances. They are aluminum, titanium or silicon. They are introduced into the welding area, and the parts themselves are heated to a temperature lower than during hot welding.

Proper preparation of cast iron for welding

Preparation of cast iron for welding must be carried out without fail; the quality of the finished seam, its strength, and wear resistance depend on it. If this process is performed correctly, it will prevent fragility and porosity of the material structure, as well as eliminate possible defects.

Preparation should consist of the following:

• sawing cracks. Often cracks in cast iron have a thin and deep structure. If the thickness of the workpiece is 4 mm, then the seam applied on top will not significantly melt the surface of the crack. This will leave a fragmented structure within the alloy base. In this case, the degree of resistance to tearing and fracture will be weak. In order for there to be good brewing in these places, it is necessary to saw the crack with a grinder using a thin disk. At the same time, the greater the thickness of the material, the deeper the sawing should be;
• drilling the edges. When visually inspecting a cast iron part, it is impossible to see the exact end of the crack depth. For this reason, before you start welding a crack, it is worth drilling small holes along its edges. A distance of 5 mm is required from the visible end of the fault. If you drill through the edges, this will ensure that the internal space is well filled with metal, as well as protect against continued splitting;
• performing edge cutting. The degree of weldability of cast iron may differ due to overheating in the area of ​​the connecting seam, which can lead to increased fragility of this area. To prevent this process, uniform heating is required over the entire length of the connection. The area of ​​the connecting seam is diluted with metal, for this purpose the correct cutting of the edges is used. When connecting thick plates, the edges are beveled at an angle of 45 degrees, while a small bluntness of 3-4 mm should be left at the base. This separation will ensure good filling of the separation area, and it will also increase the strength and wear resistance of this area;
• carrying out preforming. When welding a thin cast iron alloy product, the likelihood of liquid metal leakage increases. For this reason, in these cases it is necessary to place a graphite lining under the product; this will support the heated area and preserve the original shape of the element.

Gas welding

Gas welding of cast iron is mainly used in cases where it is required to obtain a high-strength weld, but subject to a small penetration of the surface of the base metal. At the same time, the technology of gas welding of cast iron is accompanied by the use of several welding modes, on which the quality of the final joint will depend.

The quality indicator of a welded joint is influenced by the following components:

• types of supply voltage modes;
• type of technique of the superimposed welded joint;
• current indicator;
• passing speed.

How to weld cast iron and steel using gas arc welding in order to ultimately obtain a connection with high strength without cracks, pores and other defects? To do this, you need to comply with some requirements during the workflow:

• the arc voltage indicator should be from 18 to 21 V;
• current strength - 100-120 A;
• travel speed no more than 12 m per hour;
• Welding work must be carried out using special welding wires 09G2SA or PANCH 11 with a diameter of 1 mm.

Argon welding

Welding cast iron with argon is used by many novice welders on the advice of experienced comrades, and they often resort to semi-automatic welding in an argon environment. This method is not justified for products made of cast iron alloys. The connection is obtained as in heated air, but the costs increase greatly.

The technology for welding cast iron and steel with argon usually requires the presence of a neutral environment. Of course, a seam can be obtained in an atmospheric environment, but its quality will greatly deteriorate. When welding in this environment, microcracks may form in the joint, and uneven hardening will also be observed.

If, in addition to welding, the inert gas argon is supplied, the chemical composition in the weld pool will not change in any way. If argon is used, the welding method does not matter at all. The quality of the welds is equally good for any connection of parts - butt, overlap, patch.

TIG welding of cast iron using argon is considered the most optimal option, which allows you to make a strong seam. Using gas you can cook almost any combination. If there are some difficulties in purchasing argon, then it is better to leave it for joining cast iron and steel.

Properties of cast iron

Cast iron is an alloy of iron with carbon, as well as other elements.

Characteristics of cast iron

An important factor in the production of cast iron is that the minimum amount of carbon in the alloy is 2.14% or more. If the carbon content in the alloy is below the specified amount, then this alloy is not cast iron, but is called steel. The production process for steel and cast iron is approximately the same. The main difference between these two alloys is the quantitative carbon content in their composition. Since cast iron contains more carbon than steel, cast iron is a very strong but brittle material. While steel is very flexible. It is the high carbon content in cast iron that gives this material its exceptional hardness, which is as much as 7.5 on the Mohs scale. This indicator is significantly higher than that of quartz, however, less than that of diamond, but only by 2.5 points.

The carbon in cast iron can be cementite and graphite. It is the shape of graphite and the quantitative content of cementite in the alloy that determines the type of cast iron. Thus, cast iron is divided into white, gray, malleable and high-strength. The chemical composition of cast iron, which contains impurities such as silicon, manganese, sulfur and phosphorus, is almost always constant. However, in some cases, cast iron may also contain the following alloying elements: chromium, nickel, aluminum, vanadium and others. These components are introduced into the alloy in order to give it greater strength, wear resistance, heat resistance, corrosion resistance, and non-magneticity. Cast iron containing these impurities is called alloy cast iron. The quantitative content of these impurities in the alloy determines the degree of alloying. Depending on this, there are:

• low alloy cast iron. It contains less than 2.5% of all alloying impurities;
• medium alloy cast iron. Here the impurities are about 2.5 - 10%;
• highly alloyed, containing more than 10% alloying elements.

The chemical characteristics of alloy cast irons are the main factor for their classification. Thus, among alloyed cast irons there are:

• aluminum cast iron. It contains aluminum in amounts from 0.6 to 31%. This cast iron is stronger, more heat-resistant, corrosion-resistant, and also has high wear resistance. The use of this alloy is appropriate where work is carried out in an aggressive environment and at high temperatures - thermal furnaces, chemical equipment, gas engines.
• nickel cast iron. It contains nickel in amounts ranging from 0.3-0.7% to 19-21%. Nickel content directly affects the shape of graphite precipitates in the structure of nickel cast iron. This alloy has such properties as high resistance to corrosion, high resistance to the effects of both high and fairly low temperatures on the material (heat resistance and cold resistance), and is also able to withstand exposure to such an aggressive environment as sea water. The latter property of nickel cast iron determines the high demand for this material in shipbuilding, as it is used for the manufacture of parts operating in sea water.
• chromium cast iron. This alloy contains about 32% chromium. This type of alloy cast iron has the following properties: heat resistance, corrosion resistance, wear resistance.

It is worth noting that in general the cost of alloy cast iron is significantly lower than the cost of stainless steel. In addition, they have good casting properties. In this regard, products made from this alloy are very durable, high quality, and at the same time economical.

Pig iron is extracted through the process of smelting iron ore in blast furnaces at temperatures ranging from 1150 to 12000C.

History of cast iron

Cast iron has been known to mankind since ancient times, which go back to the era BC. This is evidenced by numerous archaeological finds, among which there are both cast iron objects and the cheese furnaces themselves, in which, in fact, people received this material. However, iron is far from the first historical metal with which humanity became acquainted. Initially, people used native copper, which was mined in shallow mines. However, despite the appearance of metal in people's lives, stone remained very popular for quite a long time. Later, people learned to make bronze, and only in VI-V BC iron appeared in people's lives, and with it steel and cast iron.

The birthplace of cast iron products is China. It was there that the technology of cast iron was first mastered and this term was born, which later came to Russia through Tatar-Mongol mediation. Thus, the first cast iron products also appeared in China. It was a wide variety of everyday items, kitchen utensils, as well as coins. The wok frying pan, quite popular today, was one of the first to be made in China from cast iron. In those distant times, it was a vessel whose diameter reached one meter. This frying pan also had very thin walls. Its cost was quite high, however, despite this, this kitchen equipment was extremely popular and in demand in large Chinese families.

In addition, archaeologists find unique things cast from cast iron, among which we should note a cast iron lion, which is 6 meters high and 5 meters long. According to scientists, this statue was cast in one go. This indicates that in those distant prehistoric times, in the absence of modern high-quality technologies, Chinese metallurgists achieved enormous skill in working with metals, in particular with cast iron.

A rather interesting and somewhat unusual fact is that it is believed that malleable cast iron began to be produced only in the 19th century AD, despite the fact that archaeologists have found cast iron swords made in the pre-Christian era.

Russia and Europe became acquainted with cast iron more than a century later, namely only in the 14th – 16th centuries. At this time, cast iron was the main material for the production of artillery shells and weapons. And only in the 17th century the use of cast iron expanded significantly. This was facilitated by the development of the metallurgical industry. Gradually, the era of artillery use of cast iron ended and the era of artistic casting began - the new capital of the Russian Empire was decorated everywhere with cast fences, benches, and other elements of fine cast iron. Cast iron also caused changes in the stove business, as cast iron valves and stove doors were replaced, which had the significant advantage of resistance to high temperatures, as well as tightness, which did not allow stove smoke to escape from the stove and fill the room with smoke.

Russian metallurgists were considered the best in those days. They mastered many cast iron processing technologies, which were constantly adopted by English, French and German craftsmen.

Today, in the era of nanotechnology and technological progress, when new materials appear every year, the development of metallurgy does not stop and continues to move forward. And after more than two thousand years, humanity has not been able to find a material that could replace cast iron. It continues to be used to make various objects that surround people.

Use of cast iron

The properties of cast iron are so unique that to date no more suitable material has been found that could replace this alloy. In addition, cast iron is a fairly cheap material. In this regard, the use of cast iron remains wide and varied. The use of cast iron is especially appropriate where parts with complex shapes and high strength must be manufactured. In this regard, cast iron has found its wide application in the following areas of human activity:

• Automotive industry. In this case, cast iron with vermicular graphite is used. It is the main material for the manufacture of crankshafts of diesel engines, as well as cylinder blocks of internal combustion engines. Due to the graphite content, the strength of the alloy increases significantly, which is the main reason for the popularity of cast iron in this industry.
• plumbing equipment. As with the automotive industry, graphite cast iron is also used. This material is perfect for the production of pipes used for both drainage and water supply. It is also actively used in the production of bathtubs, sinks, washstands, fittings and much more. In this case, the products are highly reliable, do not require any specific care, and retain their original appearance for a long period.
• Oil and gas industry. Not only water pipes are made from cast iron, but also pipes for transporting, injecting and pumping out oil and gas. The main reason for using cast iron in this industry is that cast iron products have fairly high performance qualities.
• heating. Pipes and heating radiators are made from cast iron. The use of the material in this case is due to its high heat transfer, as well as good heat-storing properties, which is very important and beneficial. After turning off the heating, after an hour, cast iron pipes are able to continue to radiate heat at a third of their original power. And here cast iron completely prevails over steel, which cannot boast of such qualities, because steel pipes cool twice as fast.
• kitchen tools. The material has large pores, due to which it has the ability to absorb fat during cooking. In this regard, pots, cauldrons and frying pans are made from cast iron, the non-stick properties of which become better and better over the years. In addition, scientists have proven that when cooking in cast iron cookware, food is enriched with beneficial nutritional properties. In addition, cast iron cookware can prevent carcinogens during further storage of food.

Fences and gratings, spiral staircases, balconies, gazebos, fireplaces, lamps, pillars, lanterns, sculptures, etc. are made from cast iron.

How to identify cast iron

Knowing the material from which certain objects are made is very important. For example, it is necessary to carry out repair work on certain automotive components, individual parts or other items. This is due, first of all, to the fact that different materials lend themselves to different types and methods of processing (for example, welding, drilling, etc.).

So, cast iron can in some cases be determined visually. However, this method is suitable if there are any cracks, chips or tears in the material. If any such defects are present, it should be carefully inspected. A cast iron part that is broken or cracked will be painted dark gray and have a matte surface. While steel will have a light gray, closer to white, color and glossy shine. If you look closely at the surface defects, cast iron will have characteristic hemispherical small grains. Unfortunately, this method is not an accurate determination of the material, since it is possible to determine “by eye” whether it is cast iron or not only if the alloy (in this case cast iron) was poured into the mold at a low temperature, was not further processed and was not coated no paints and varnishes. It is the characteristic small hemispherical grains that indicate the pouring of the alloy at high temperatures.

The mechanical method can provide more information in determining cast iron. To do this, it is necessary to obtain alloy shavings. This can be done by drilling to a shallow depth in some area of ​​the non-working part. For high-strength cast iron, the shavings will be characteristic - they will crumble, grinding into dust in the hands and leaving a mark on the fingers, similar to the lead of a simple pencil. Cast iron shavings are not able to wrap themselves in a twisted rope. This is due to one of the properties of cast iron - fragility.

If you try to cut a cast iron product with a grinder, then short sparks will fly from it, having a reddish tint on the star at the end of the track.

All of these options are valid for determining cast iron at home. However, they cannot give a 100% determination. To more accurately determine the alloy, spectral analysis, microscopic analysis, as well as weighing and volume determination are used.

Features of caring for cast iron cookware

After any type of cleaning, measures must be taken to create a protective layer on the cast iron to prevent corrosion in the future:

• turn on the oven at 180 degrees, warm it up;
• grease the frying pan with oil (any oil except olive oil), applying a thin layer;
• place the product in the oven, bottom up, leave for 60 minutes;
• turn off the cabinet, do not take out utensils for another hour;
• Remove the pan, rinse, wipe dry, and put away for storage.

Cast iron should always remain a little greasy - this will allow it to maintain protection against corrosion for a long time. In the future, you should follow these care tips:

• Always wait for the product to cool down and only then start washing it;
• after each wash, lubricate the item with vegetable oil and heat for 1-2 minutes;
• do not leave the pan with ready-made liquid food for a long time - after cooking, pour it into another container;
• do not use aggressive detergents, brushes, or abrasives on a regular basis, they wash off the protective layer and the cast iron rusts faster;
• to remove burnt food, soak the dishes in warm water, then easily remove the remains with a washcloth;
• do not forget to use the dishes regularly so that they do not stand idle;
• do not wash in the dishwasher;
• Do not cook acidic food, which corrodes the protective layer.

High-quality care of cast iron will keep the product in excellent condition, eliminate the appearance of rust, while maintaining its non-stick properties and ability to retain heat.

Sources

• https://jgems.ru/metally/chugun
• https://stroyres.net/metallicheskie/vidyi/chyornyie/chugun/ponyatie-osobennosti.html
• https://metallicheckiy-portal.ru/articles/chermet/raznoe/chto-takoe-chugun-sostav-i-soderzhanie-ugleroda-v-splave/
• https://elton-zoloto.ru/raznoe/skolko-procentov-ugleroda-imeetsja-v-sostave-chuguna.html
• https://lux-stahl.ru/metally-i-splavy/izbytok-alyuminiya-v-chugunah-vyglyadit-kak.html
• https://ometalledo.ru/soderzhanie-ugleroda-v-chugune-i-stali.html
• https://www.syl.ru/article/304510/chto-takoe-chugun-svoystva-sostav-poluchenie-i-primenenie
• https://sakhkor.ru/materialy/vidy-chuguna.html
• https://morflot.su/procentnoe-soderzhanie-ugleroda-v-chugune/
• https://metallvsegda.ru/poleznoe/chto-takoe-chugun-sostav-i-soderzhanie-ugleroda-v.html

Malleable iron

Malleable cast iron is called cast iron obtained from white (half) cast iron by prolonged annealing (simmering). The scheme for producing malleable cast iron is shown in Fig. 3.

Rice. 3. Scheme for producing malleable cast iron by annealing (simmering) half-cast iron: 1 - curve for producing malleable ferritic cast iron; 2 - curve for producing malleable pearlitic cast iron; t—temperature; τ — time; Ac1 - critical temperature (eutectoid)

The process of producing malleable cast iron is as follows. In cupola furnaces or electric furnaces, low-grade (half-grade) white cast iron is melted, then poured into earthen or metal molds. Once cooled, the castings are removed from the molds and placed in boxes containing crushed iron ore or scale. The boxes are heated in ovens to a temperature of 900 ... 1,000 ° C and kept for 6-10 days. During this thermal operation (simmering), carbon from cementite diffuses to the surface of the part, turning into free carbon in the form of graphite (annealing carbon), and part of it burns out.

Currently, the technology of accelerated annealing of white cast iron castings onto malleable cast iron has been introduced. The essence of this technology is to carry out preliminary heat treatment of castings: normalization or hardening and tempering. These operations make it possible to obtain a larger number of crystallization centers, which leads to faster decomposition of cementite into annealing carbon and significantly reduces the duration of the process of producing malleable cast iron.

Quenching is carried out at a temperature of 820 ... 950 ° C and cooled in mineral, spindle or transformer oil. Tempering is carried out at a temperature of 400 °C. During the second stage of final annealing at a temperature of 950 °C, the duration is reduced to 5 hours.

In practice, stepwise annealing is also used: castings are cooled from 950 to 760 °C for 2 ... 3 hours, from 760 to 680 °C for 8 ... 10 hours, then cooled in air.

Modern accelerated production of malleable cast iron is carried out in two stages. The first stage is heating of castings in salt baths or molten metals at 1,050 ... 1,100 ° C and holding for 1 ... 2 hours; the second is heating to 700 °C and holding for 4 hours. The whole process also lasts 5 ... 7 hours. As a result of annealing in the castings, the structure of ledeburite and cementite transforms into the structure of flake-shaped graphite (annealing carbon). Compared to the original cast iron, the hardness of malleable cast iron castings is reduced, brittleness is eliminated, strength is increased, and the castings acquire high ductility (up to 12%) and impact strength. Due to its high ductility, this cast iron is called malleable cast iron, but this cast iron is not subject to forging, especially it cannot be forged (deformed) in a hot state, since cast iron becomes brittle along the grain boundaries in a hot state, and microcracks appear. After forging, castings become brittle. Ductile iron castings undergo slight deformation in a cold state, bend, stretch, and straighten.

The structure of malleable cast iron in the form of flake graphite has higher hardness, strength and ductility compared to gray cast iron. As practice has shown, half-cast iron castings subjected to annealing for malleable cast iron should have a diameter of no more than 40 ... 50 mm. With a cross section of more than 50 mm, a very hard and brittle structure of lamellar graphite is formed in the core.

Ductile iron castings have the following impurity content: carbon - 2.4 ... 2.9%, silicon - 1.0 ... 1.6%, manganese - 0.2 ... 1.0%, sulfur - up to 0.2% and phosphorus - up to 0.18%.

The structure of malleable iron castings, depending on the annealing conditions, can be ferritic or ferritic-pearlite (Fig. 4). The ferrite and carbon annealing structure is obtained by step annealing. Castings obtained by stepwise annealing have ductility up to 12%.

Rice. 4. Microstructures of malleable cast iron: a - ferritic (black-core); b - ferrite-pearlite (light-heart)

Malleable pearlitic iron castings are produced by prolonged annealing at a temperature of approximately 1,000 °C. After the first stage of graphitization, slow continuous cooling is carried out to normal temperature. After cooling, the castings develop a pearlite and annealed carbon structure. The structure of pearlite determines higher mechanical properties of parts, strength and hardness. During annealing, casting stresses are relieved in castings.

According to GOST 1215-79**, the following grades of malleable cast iron are produced: KCh 30-6, KCh 30-8, KCh 35-10, KCh 37-12, KCh 45-7, KCh 50-3, KCh 50-4, KCh 60 -3, KCh 65-3, KCh 70-2, KCh 80-1.5, where KCh is malleable cast iron; the first numbers indicate tensile strength, the numbers after the hyphen indicate elongation.

Malleable cast irons are used for the manufacture of parts with small cross-sections that operate under severe conditions: abrasive wear, shock and alternating loads, in the automotive, tractor and textile engineering, boiler, carriage and diesel industries.

The high strength and density of ductile iron castings makes it possible to widely use them as water supply and gas installations and equipment.

The disadvantage of malleable cast iron is the high cost of castings due to long annealing and metallurgical units with special equipment.

To change the microstructure of ductile iron castings after machining, they are subjected to various types of heat treatment: normalization, hardening and subsequent tempering. During the heat treatment process, the metal base of the castings changes, after which the hardness, wear resistance, strength and impact strength increase.