Frequently used in household products of the metallurgical industry are cast iron and steel. Both materials are a unique alloy of iron and carbon. But the use of identical components in production does not give materials similar properties. Cast iron and steel - two various material. What are their differences?

Steel

To get steel, it is necessary to rush iron, carbon and impurities. In this case, the carbon content in the mixture should not exceed 2%, and it is at least 45% iron. The rest of the percentage in the mixture can be alloying elements (binding a mixture of substance, for example, molybdenum, nickel, chromium and others). Thanks to carbon, iron acquires strength and limiting hardness. Without his participation, a viscous and plastic substance would be obtained.

Cast iron

In the production of cast iron, iron and carbon are also fused. Only the content of the latter in the mixture is more than 2%. In addition to the listed components, the mixture contains constant impurities: silicon, manganese, phosphorus, sulfur and alloying additives.

Difference

In metallurgy distinguish a fairly large number of types of steel. Their classification depends on the number of one or another component in the mixture. For example, a large content of binding elements gives high-alloy (more than 11%) steel. In addition, there are:

• low alloy - up to 4% of binding components;
• the totalized - up to 11% of the binding elements.

• low carbon metal - up to 0.25% C;
• mid-carbon metal - up to 0.55% C;
• high carbon - up to 2% s.

And finally, depending on the content of non-metallic inclusions, which are formed as a result of reactions (for example, oxides, phosphides, sulphides), a classification of physical properties is carried out:

• especially high quality;
• high quality;
• high-quality;
• ordinary steel.

This is not a complete classification of steel. Still distinguish views on the structure of the material, the production method and so on. But in no matter how much the main components were fused, it is ultimately solid, durable, wear-resistant and strain-resistant material with a specific weighing of 7.75 (up to 7.9) g / cm 3. The melting point of steel - from 1450 to 1520 ° C.

In contrast, the cast iron became more fragile, it distinguishes the ability to collapse without noticeable residual deformations. At the same time, the carbon itself in the alloy is represented in the form of graphite and / or cementite, their form and, accordingly, the amount determines the varieties of cast iron:

• white - all the necessary carbon is contained in the form of cementite. Material white on a break. Very firm, but fragile. It is processed and mainly used to obtain a forging of varieties;
• gray - carbon in the form of graphite (plastic form). Soft, perfectly processed (can be cut) and has a low melting point;
• dusty - it turns out after a long annealing of a white view, as a result of which graphite is formed. Heating (over 900 ° C) and graphite cooling rate negatively affect the properties of the material. It makes it difficult for welding and processing;
• high-strength - contains spherical graphite formed as a result of crystallization.

Conclusions Site

1. Steel is more durable and firm than cast iron.
2. Cast iron is easier than steel, and has a lower melting point.
3. Thanks to the lower carbon content, the steel is better to be processed (welding, cutting, rolling, forging), rather than cast iron.
4. For the same reason, the product from the cast iron is made only by casting.
5. Cast iron products are more porous (due to casting) than steel, and therefore their thermal conductivity is significantly lower.
6. Usually artistic products from iron black and matte, and from steel - light and brilliant.
7. Cast iron has low thermal conductivity, and steel is higher.
8. Cast iron is a primary product of ferrous metallurgy, and steel - finite.
9. The cast iron is not hardened, and some types of steel must be subjected to the ordering procedure.
10. Products made of cast iron are only litas, and from steel - forged and welded.

Cast iron and steel - two varieties of iron compounds with carbon - find labor application in various industries. But sometimes it becomes necessary to distinguish cast iron from steel, for example, when repairing, because these alloys possess different properties And, accordingly, require different circulation.

Ways to define cast iron

You can define cast iron by product density. Weigh the subject, and then determine how much water it displaces. So you will calculate its density and make a conclusion about the material. The fact is that the density of the main steel grades lies in the range of 7.7 - 7.9 grams / cm ^ 3, the density of the most common gray cast iron does not exceed 7.2 grams / cm ^ 3. But this is a way unreliable, since there is still white cast iron, the density of which ranges between 7.6 and 7.8 grams / cm ^ 3. Therefore, it can be used only being firmly confident: the product is made either of steel or from gray cast iron.

Therefore, it is more reliable to use one of the following methods: to determine the cast iron using the type of sawdust or chips formed, as well as with a grinding machine. Take a file with a shallow notch, spend several times on the surface of the product. Try to assemble the smallest sawdust on the paper sheet. Fold twice the paper and vigorously. If it is cast iron, the paper will be noticeably fan, if it is steel, traces almost will not remain.

You can also screw a little to the product with a thin drill (of course, not from the front side, but in a place that does not rush into the eyes). This forms a small amount of chips. By her appearance and properties can be unmistakable to determine which material is made of the part. If it is cast iron - the chips literally crushes in your fingers, turning into dust. If it is steel - the chips will look like a twisted spring and may even scratch your fingers if you try to break it.

If there are doubts - it is better to use slices of iron and steel as the standards and to compare the form and properties of sawdust (chips), as well as the type of claims formed with what is obtained during the processing of these samples.

Cookware for induction surface

There is China and China. In Ikea, the whole stainless steel of Chinese production, but brand holders (Swedes, and now - seems to be the Dutch) tightly control the production. As a result, it seems to me, the ratio of price / quality in a very unpretentious Ikeevian pancro pans is one of the best in our market. Everything works on the induction panel - if stated.

Most of the global brand electronics is done in China. From another "household" garbage, I can call some knife manufacturers. Worse, when the brand is Chinese, but also there is a quick progress: there are things
(for example, in electronics, in the production of buses), which the Chinese under the control of the state began to be made very well. But when our business sharks are included in the game, creating "German" brands and insertive laid-up labels on the products of Chinese unknown and uncontrolled artisans - here the current hold on.

I heard that in the times of perestroika cooperatives in Odessa, the top shik was considered not to fake sneakers under the company "Addidas", but their handicrafts for the Chinese fake "Addidas". This style has all the knees and preserved - everywhere. Swal and cattle, crushing their own.

Hospadi! Yes, when this notorious "magnet" disappears from culinary communities. The classic "food stainless steel" - steel "18/10" - it does not attract any "permanent magnets", but it is a great way suitable for induction plates.

how to distinguish cast iron from steel.

Members.

1967 messages

• City: Ukraine
• Name: Sergey Savelyevich

how to distinguish cast iron from steel.

Look carefully on the crankshaft, cast iron - cast, steel commonly forged from the whole piece of steel. It is possible to almost accurately determine in appearance. By the way, what kind of engine crankshaft? And once again, by the way, the overwhelming majority of cast iron cast-iron crankshafts. Obviously cast cheaper and easier than to kill.

# 16 Sergey19

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84 messages

• City: Barnaul
• Name: Sergey

how to distinguish cast iron from steel.

How? They are equally lipped.

# 17 vladimir_v

Members.

2163 messages

• Voronezh city

how to distinguish cast iron from steel.

Magnet is much worse lipot to the cast iron than to steel.

No, to durable cast irons as well.
You can leave in a secluded place with a small knife. Miligram remove. The cast iron does not form chips - in general, it will be drilled at all like steel. To pack the chamorer, it is enough to sew any knowing cast iron.

# 18 khatru

Members.

4432 messages

• Moscow city
• Name: Dmitry.

how to distinguish cast iron from steel.

Cast iron does not form chips

i thought so too. And recently drilled the building of the old Soviet hydromotor. Taki spiral chips, though short - 20-30. Although cast iron is definitely. apparently depends on the brand and so

# 19 vladimir_v

Members.

2163 messages

• Voronezh city

how to distinguish cast iron from steel.

taki spiral chips,

Maybe the chips - but it turns his fingers into the dug. And the steel drain as a wire, you can not be broken.

# 20 khatru

Members.

4432 messages

• Moscow city
• Name: Dmitry.

how to distinguish cast iron from steel.

Maybe the chips - but it turns his fingers into the dug

may be. Because short. I have not tried my fingers. Yes, and out of the milligram you will not understand - it is very less cube mm 🙂

You can define cast iron by product density. Weigh the subject, and then determine how much water it displaces. So you will calculate its density and make a conclusion about the material. The fact is that the density of the main steel grades lies in the range of 7.7 - 7.9 grams / cm ^ 3, the density of the most common gray cast iron does not exceed 7.2 grams / cm ^ 3. But this is a way unreliable, since there is still white cast iron, the density of which ranges between 7.6 and 7.8 grams / cm ^ 3. Therefore, it can only be used by being firmly confident: the product is made either of steel or from gray cast iron.

You can use a magnet. To the cast iron, he sticks worse than the steel. But this way is impossible to call this way, since some types of alloyed steels with a high nickel content almost do not attract a magnet.

Therefore, it is more reliable to use one of the following methods: to determine the cast iron using the type of sawdust or chips, as well as with a grinding machine. Take a file with a shallow notch, spend several times on the surface of the product. Try to assemble the smallest sawdust on the paper sheet. Fold twice the paper and vigorously. If it is cast iron, the paper will be noticeably fan, if it is steel, traces almost will not remain.

You can also screw a little to the product with a thin drill (of course, not from the front side, but in a place that does not rush into the eyes). This forms a small amount of chips. According to her appearance and properties, it is possible to unmistakably determine from what material the item is made. If it is cast iron - the chips literally crushes in your fingers, turning into dust. If it is steel - the chips will look like a twisted spring and can even scratch your fingers if you try to break it.

Finally, it is possible to judge the material in magnitude, form and color of the sparks, which are formed when the product is carried out on the edge of the product with a grinding machine. The greater the carbon content, the brighter and the sheaf of light yellow sparks will be stronger. And carbon content in cast iron is much higher than in steel.

If there are doubts - it is better to use slices of iron and steel as the standards and to compare the form and properties of sawdust (chips), as well as the type of claims formed with what is obtained during the processing of these samples.

In his life, we often have to deal with various products from cast iron. Which in its structure is a rather fragile alloy, but with good thermal conductivity. In accordance with this, the question often arises, and how to cook it, because the cast iron is due to the high content of carbon, sulfur and phosphorus in it relates to a group of poorly welded metals?

Having lowered the subtlety of the chemical composition of cast iron, chemical and other processes occurring during welding, let's still figure out: how to cook cast iron? The industry of our country produces gray and white cast iron, which are very different in their composition and characteristics. Accordingly, there are different welding methods for them. It must be remembered here that cook products from cast iron, which for a long time We were exposed to high temperatures from 300 degrees and above, as well as products, worked in direct contact with various oils for a long time, almost not possible.

The most acceptable method of welding cast iron in our household conditions is welding using the electric welding machine. So, with the electrical welding, you spend the V-shaped cutting of the welded edges and thoroughly clean them from oil, rust and dirt brushed.

Purchase electrodes coated Woney-13/45 (welding with these electrodes is carried out at a constant current of reverse polarity).

Welding seam superimpose (broken down), it will help you avoid uneven warming up the part (separately directional sections welding seam There must be no more than 10 cm). When welding products with a thickness of more than 5 mm Do not forget to reinforce the seam to the length equal to the thickness of the welded part.

During welding, do not forget to make it cool separately by the flooded plots up to 60-80 degrees. When welding cast iron using studs, do the following: With the help of a drill (in a checker order), drill in the prepared edges of the holes (not through!), Cut the threads and screw them into them. Stiles from low carbon steel (the angle of the edges of the welded parts should be 90 degrees).

Insert the strips of the larger diameter. The welder is made by electrodes with a protective-alloying coating of the E42 brand (42a) or e50 (50a) on a constant or alternating current, while the thickness of the electrode is selected depending on the thickness of the product.
Welding itself, follow the wardring of the spree of the ring seam and only after that with short areas fill the space between the fed lines and the cut itself. There is also other ways to welding the cast iron, but we will talk about them later.

Information, calculations, calculators,
GOST

Magnetic properties of cast iron

In accordance with the requirements for items and details, cast iron can be used as a ferromagnetic (magnetic-soft) or a ferrynetic material.

Magnetic properties are more than any other, depend on the structure of the metal, which determines the separation of magnetic properties to primary and secondary. Primary include induction, saturation (4πi). Permeability in strengths and temperature of magnetic transformation. These properties depend on the number and composition of ferromagnetic phases and do not depend on their shape and distribution. The secondary properties include hysteresis characteristics: induction, saturation and permeability in weak and medium, fields, coercive force, residual magnetism. Secondary properties are little dependent on the composition of the phases and are mainly determined by the shape and distribution of structural components.

The main ferromagnetic components of the cast iron are ferrite and cementite, characterized by the following data (Table 1).

Table 1. Characteristics of structural components of cast iron

T magnetic transformation, ° C

Cementite is a more rigid magnetic component, therefore gray, not white cast iron, is always used as a magnetic and soft material. Graphitization leads to a sharp decrease N S. and intensive increase μ MAX In particular, during the decay of the last remnants of carbides. In this case, the effect of graphite, as well as other non-magnetic phases, also depends on the shape and size of inclusions. The most favorable in this regard is a globular form. Therefore, dowy and high-strength cast iron are characterized by greater induction and magnetic permeability and less coercive force than gray cast iron with the same matrix (see Table 1 in the electrical properties of the cast iron).

In the same way, the enlargement of eutectic and ferritic is true and a decrease, the number of perlite. Therefore, leave after hardening contributes to the improvement of magnetic and soft properties.

Non-magnetic (paramagnetic) cast irons are used in cases where it is required to minimize power loss (oil switch covers, transformer end box, pressure rings on electromashins, etc.) or when minimal distortion is required magnetic field (Racks for magnets, etc.). In the first case, along with low magnetic permeability, highly required electrical resistance; This requirement of cast iron satisfies even to a greater extent than colored alloys. In the second case, a particularly low magnetic permeability is necessary. Therefore, in some cases, it is not possible to replace the colored alloys with austenitic castlers for the second group of castings.

Depending on the composition, austenitic non-magnetic cast iron distinguishes:

• nickel type lorester with one or another chrome;
• nickel Martensal-type NOMAG with one or another content of copper and aluminum, superior cast iron of the first group of non-magneticity, but inferior to them on heat resistance, heat resistance and corrosion resistance;
• manganese with one or another content of copper and aluminum, which are the cheapest, but possess lower strength and physical properties.

Ferritic high-alloyed aluminum cast iron, characterized by particularly low magnetic permeability, are of interest.

The products of ferrous metallurgy are widely used in many sectors of the national economy, and the black metal is always in demand in construction and mechanical engineering. Metallurgy has long been successfully developed, due to its high technical potential. The most commonly used in the production and in everyday life cast iron and steel products.

Cast iron and steel both belong to the group of ferrous metals, these materials are unique in their properties of iron alloys with carbon. What are the differences of steel and cast iron, their main properties and characteristics?

Steel and its main characteristics

Steel is deformed Iron Alloy with Carbonwhich is always a maximum of up to 2%, as well as other elements. Carbon is an important component, because it gives strength to iron alloys, as well as hardness, due to this decreases softness and plasticity. Alloying elements are often added to the alloy, which ultimately gives alloyed and high-alloy steel, when the composition of at least 45% of iron and no more than 2% of carbon, the remaining 53% are additives.

Steel is the most important material in many industries, it is used in construction and as the technical and economic level of the country grows, and the scale of steel production is growing. In the old times, a crucible melting was used to obtain cast steel and such a process was low-performance and time consuming, but the steel was distinguished by high qualities.

Over time, the processes of obtaining became changed, Besmorerorsky came to replace the crank martenovsky method obtaining steel, which made it possible to establish mass production of cast steel. Then steel began to sell in electrical furnaces, after which an oxygen-converter process was introduced, it allowed to obtain a particularly clean metal. From the quantity and types of binding components, steel can be:

• Low alloyed
• Mession
• High-alloyed

Depending on the carbon content It happens:

• Low carbon
• Medium carbon union
• High carbon.

Metal often includes non-metallic compounds - oxides, phosphides, sulphides, their content is different on quality steel, there is a certain classification of quality.

Steel density is 7700-7900 kg / m3, but general characteristics steel fold from such indicators as - strength, hardness, wear resistance and suitability for processing of various types. Compared to the cast iron, steel has a greater plasticity, durability and hardness. Thanks to the plasticity, it is easily processed, the steel is characterized by a higher thermal conductivity, and its quality is increased by hardening.

Such elements like nickel, chromium and molybdenum are alloying components, each of them gives their own characteristics. Thanks to the chromium, steel becomes more durable and solid, its wear resistance increases. Nickel also gives strength, as well as viscosity and hardness, increases its anti-corrosion properties and calcination. Silicon reduces viscosity, and manganese improves the quality of weldability and calcination.

Everything existing species Steel have melting point from 1450 to 1520 ° C And they are strong wear-resistant and resistant to deformations of metal alloys.

Cast iron and its main characteristics

The basis of the production of cast iron is also iron and carbon, but in contrast to carbon steel in it more, as well as other impurities in the form of alloying metals. It differs in fragility and destroys without visible deformation. Carbon here performs graphite or cementite and due to the content of other elements cast iron is divided into the following varieties:

The melting point of the cast iron depends on the content of carbon in it than its larger in the composition of the alloy, the less temperature, and also increases its fluidity during heating. This makes the metal of non-vigorous fluid, as well as fragile and difficult to process. Its melting point is from 1160 to 1250 ° C.

Anti-corrosion properties in cast iron is higher because it is subjected to dry rust in the process of use, it is called chemical corrosion. Wet corrosion also affects cast iron slower than steel. These qualities led to the fact that the opening of metallurgy was performed - they began to pay steel with a high chromium content. From here there appeared stainless steel.

We conclude

Based on their numerous characteristics, we can say the following about cast iron and steel, what is their difference:

It can be concluded that steel and cast iron combines the content of carbon and iron content, but their characteristics are distinguished And each of the alloys has its own characteristics.

Modernity is iron. The versification knows that under the word "Iron" refers to iron carbon alloys - steel and cast iron. It would seem that two absolutely different material and their very easy to distinguish. However, given a wide range of their species and brands, a thin face of differences in chemical composition Some of them are difficult to determine. It is important to have additional skills in order to know the answer to the question: cast iron from steel than different?

Cast iron

Characteristics:

1. Grungy, having gray matte color.
2. Melting at 1000-1600 ° C, depending on the composition (for industrial on average - 1000-1200 ° C, white and alcohol cast iron melted at higher temperatures).
3. Density: 7200-7600 kg / m 3.
4. 540 J / (kg˚С).
5. High hardness: 400-650 NV.
6. Low plasticity, very crushes when exposed to pressure; highest values Relative elongation has a ductile high-strength cast iron Δ \u003d 6-12%.
7. Low strength: 100-200 MPa, 300-370 MPa for a dweller, for some high-strength brands - 600-800 MPa.
8. It is modeled using heat treatment, but rarely and with great care, since the process of cracking is characteristic.
9. Allocated with auxiliary chemical elements, however, a significant degree of doping complicates technological processing processes.
10. It is characterized by a satisfactory weldability, good processed cutting, excellent foundry properties. Forging and stamping is not subject to.
11. Good wear resistance and corrosion resistance.

Cast iron - material for cabinet parts, blocks, nodes of machines made by casting. Is the main mixture component for

Steel

The iron-carbon alloy containing carbon in the amount of no more than 2.14% and iron is at least 45%, called steel. Its main characteristics:

1. Smooth, has a silver color with a characteristic reflections.
2. Melting within 1450 ° C.
3. The density ranges from 7700 to 7900 kg / m 3.
4. Heat capacity at room temperature: 462 J / (kg˚С).
5. Low hardness, an average of 120-250 HV.
6. Excellent plasticity: the relative elongation coefficient Δ for different brands varies within 5-35%, for most - δ≥20-40%.
7. Average strength limit for structural materials - 300-450 MPa; For particularly durable alloyed - 600-800 MPa.
8. It is well amenable to correction of properties with thermal and chemical processing.
9. Actively dumping various chemical elements In order to change properties and destination.
10. Qualitatively high rates weldability, pressureability of pressure and cutting.
11. It is characterized by low rates of corrosion resistance.

Steel is the main construction alloy in modern metallurgy, mechanical engineering, instrument making and technique.

Determine the origin of the type of details

Examined detailed features These alloys can confidently use knowledge about the cast iron from steel than different. Having a metal object, doubting its origin, is rationally immediately remember the main distinctive technological properties. So, cast iron is a casting material. It produces simple dishes, massive pipes, machine housings, engines, large objects of a simple configuration. From steel make parts of all sizes and difficulties, as for this applies forging, stamping, drawing, rolling and other methods in such a way, if there is a question about the origin of the reinforcement, there can be no doubt - this is steel. If interested in the origin of the massive cauldron is cast iron. If you need to know from which the engine or crankshaft case is made - you should resort to other variants of recognition, since both options are possible.

Color features and analysis of fragility

In order to know how to distinguish cast iron from steel on the eye, you need to remember the main visual differences. For cast iron, a matte gray color and a scratched exterior texture is characteristic. Steel is characterized by a special silver brilliant shade and minimal roughness.

Also important knowledge about how to distinguish cast iron from steel visually is information about the plasticity of these materials. If the underlying billets or metal objects do not have a serious value, you can try their strength and plasticity by applying shock power. The fragile cast iron will turn into pieces, while the steel is only deformed. With more serious loads aimed at crushing, crumbs of cast iron are fine diverse, and the pieces of steel are large, the correct configuration.

Cut and drill

How to distinguish cast iron from steel at home? It is necessary to get fine dust or chips from it. Since steel has a high plasticity, it also has a malicious character. The cast iron will crumble, when drilled, a small chips are formed with dust together with dust.

To obtain dust, you can use the file or rashpyl and a little to appeal to the edge of interest. The resulting fine chips examine on hand or white sheet of paper. Cast iron contains carbon in large quantities In the form of graphite inclusions. Therefore, when rubbing his dust, a black graphite "mark" remains. In the stals, carbon is in the bound state, so the mechanical effect on dust does not give any visible results.

Heat and sick

How to distinguish cast iron from steel? Need to operate necessary equipment and a small margin of patience.

In the first case, you can resort to heating, for example, with a soldering lamp, having initially into special protective clothing and complying with the safety rules in operation. Temperature should be raised before the melting of metal. It has already been said that the melting point of the cast iron is higher than that of steel. However, this concerns mostly white and relatively all industrial brands - they contain carbon in the amount of not more than 4.3% and melt at 1000-1200 ° C. Thus, it can be melted much faster.

The cognitive method of obtaining information about the cast iron from steel than different is the use of an experimental sample on a grinding machine or under an acute grinding machine. The analysis is carried out according to the characteristics of the spark. The cast iron is characterized by inappropriate sparks of red, and for steel - bright blinding short rays with a white and yellow tint.

As it sounds

An interesting feature is how to distinguish cast iron from steel by sound. These two alloy sound differently. It is not necessary to produce a musical accompaniment on existing experimental objects. But you need to have both samples either possess experienced hearing in this issue. Steel is characterized by more high densityWhat is reflected on her sound. When you hit it with a metal object, the sound is much better than the call, rather than in the same situation with the cast iron.

In order to know the cast iron from steel than different, it is necessary to have some knowledge of these materials and a certain experience. After all, an experienced professional in the field of forging, grinding, milling, drilling, sharpening, heat treatment or welding, metallurgist or techniques easily distinguishes them between themselves, appreciating only visual or touch.

Cast iron and steel products of the metallurgical industry are used both in everyday life and production. Both materials are unique iron and carbon alloys. Everyone knows that iron is mined from the depths of the Earth in huge quantities. BUT B. pure form It is impossible to operate it, this element is too soft, and therefore unsuitable for the manufacture of high strength products. Therefore, in industrial, construction and forgoing purposes, it is used not iron in its pure form, but its derivatives are -chugun and steel. What is the difference between steel from cast iron?

Cast iron and steel are iron and carbon alloys.

Their difference is manifested in many qualities, and the community of elements in production does not give material identical characteristics.

Gradation of steel and cast iron

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Steel

To obtain steel steel, iron is melted with carbon and a variety of impurities. Mandatory condition is the carbon content of no more than 2% (it increases strength), and iron is at least 45%. The remaining part is allocating binding components (chromium, molybdenum, nickel, etc.). Chrome increases steel strength, its hardness and wear resistance. Nickel increases strength, viscosity and hardness, increases its anti-corrosion quality and calcination. Silicon adds strength, hardness and elasticity of steel, reduces its viscosity. Manganese improves weldability and calcination. Motlurgi allocate different types become. Classify them depending on the volume of the leaving elements. For example, the content of more than 11% of alloying metals gives high-alloy steel. There is also:

1. Low-alloy steel - up to 4%.
2. Solid-level steel - up to 11%.

By carbon number, steel is classified on:

• low carbon metal - up to 0.25% C;
• mid-carbon metal - up to 0.55% C;
• high carbon metal - up to 2% C.

The composition of non-metallic elements (phosphides, sulphides) classifies the metal to:

• ordinary;
• high-quality;
• high quality;
• particularly high quality steel.

As a result, all types of steel are durable, wear-resistant and strain-resistant alloy with a melting point of 1450 to 1520 ° C.

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Cast iron

In the production of cast iron, iron and carbon is also melted. The main difference of cast iron from steel is the content of the latter in the mixture. It should be more than 2%. In addition, the mixture contains impurities: silicon, manganese, phosphorus, sulfur and alloying metals. Cast iron is more fragile than steel, and destroyed without visible deformation. Carbon in the metal is represented by graphite or cementite, while the volume and form of the element give a definition of the species of the alloy:

1. White cast iron in which the entire volume of carbon is represented by cementite. At the break, this material has white color, very solid, but at the same time fragile. It is easy to process and is used to produce forging species.
2. Gray - carbon is represented by graphite that gives material plasticity. Soft, subject to cutting, low melting point.
3. Making, which is obtained from a white cast iron with a special annealing (gravy) in singular heating ovens at a temperature of 950-1000 ° C. In this case, excessive fragility and hardness characteristic of white cast iron are much reduced. Dake cast iron does not go, and the name points only on its plasticity.
4. High-strength cast iron containing spherical graphite formed during crystallization.

The amount of carbon in the alloy is determined by the temperature of its melting (the greater the content of the element, the lower the temperature and above the fluidity during heating). Therefore, the cast iron is a liquid, non-control, fragile and difficult to process material with a melting point of 1150 to 1250 ° C.

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Resistance to corrosion

Both alloy are subject to corrosion, and improper operation contribute to the acceleration of this process.

Cast iron in the process of use is covered on top of dry rust. This is the so-called chemical corrosion. Wet (electrochemical) corrosion affects cast iron more slowly than on steel. Initially, it is suggested that the anti-corrosion characteristics of the cast iron is much higher. In fact, both of these alloy are subject to corrosion equally, simply in relation to cast-iron products due to thick walls, the process takes longer. This, for example, can be explained by the difference in the service life of the boilers: steel - from 5 to 15 years, cast-iron - from 30 years.

In 1913, Harry Breearley made a discovery in the field of metallurgy. He discovered that steel with a high chromium content has a good resistance to acid corrosion. So stainless steel appeared. She also has its graduation:

1. Corrosion-resistant steel has a resistance to corrosion in elementary industrial and living conditions (oil and gas, light, engineering industry, surgical instruments, household stainless facilities).
2. Heat resistant steel resistant to high temperatures and aggressive environments (chemical industry).
3. Heat supply steel is characterized by increased mechanical strength in high temperatures.

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Thermal shock and impact resistance

Cast iron and steel are often used in the manufacture of heating boilers. At the same time, the problem of resistance to thermal impacts becomes especially important. If an uncomfortable cast iron boiler falls cold waterHe can crack. Steel product thermoshok is not terrible. Steel is more elastic and perfectly transfers the difference in temperatures. But the large and frequent temperature differences in steel contribute to the appearance of "tired" zones and, as a result, cracks in places that are weakened by welding.

Good plasticity makes steel products resistant to mechanical damage. The fragility of the cast iron inevitably leads to the formation of cracks during blows or skews.

Gray cast iron has a more homogeneous structure, elevated plasticity and anti-corrosion properties, is able to withstand large temperature dries.

1. Cast iron is less durable and firm than steel.
2. Steel is heavier and has more high temperature melting.
3. More low content Carbon in steel as opposed to cast iron makes it more easily to process it (cook, cut, rive).
4. For a similar reason, pig-iron products are produced only by casting, the steel can be forged and welded.
5. The products made of less porous than from the cast iron, and therefore their thermal conductivity is significantly higher.
6. Products made of cast iron have, as a rule, a black color and a matte surface, and from steel - bright with a shiny surface.