High carbon steel. What are LED strips? What is a boiler room? Who manufactures metal structures

Carbon steel is an alloy of iron and carbon. Carbon increases the rigidity of the alloy structure, steel becomes hard and durable, but loses its ductility. By changing the amount of carbon, the properties necessary for the application of the metal are obtained. The minimum carbon content in the alloy is 0.05–0.25%; based on their qualitative composition, such alloys are classified as low-carbon.

Low-carbon steels are not hardened; due to their softness and plasticity, the seams are well welded by all types of welding, the workpieces are easily processed by forging and rolling.

Variety of low carbon steels

Low-carbon alloys contain impurities of various types. Increased sulfur and phosphorus content directly affect the properties of the metal and can lead to cracking during processing. Manganese and silicon do not reduce characteristics; they participate in the process of deoxidation and oxygen removal. Oxygen is removed to increase the strength of the material during hot deformation.

According to the degree of oxygen removal and deoxidation, steel is classified into:

• boiling;
• calm;
• semi-calm.

Low-alloy steels are an alloy with a low carbon content and small amounts of alloying additives, a total ratio of up to 4%. Alloying elements are needed to increase any performance properties while maintaining good welding characteristics. Increased metal resistance to corrosion, the ability to work at extremely low and high temperatures without deformation is achieved.

The quality of low-carbon steel is determined by the content of impurities and phosphorus in the alloy.

Based on the type of properties, they are distinguished:

• Usual quality. Sulfur in the composition - up to 0.06%, phosphorus - up to 0.07%.
• High quality steel. Mass fraction of sulfur - up to 0.04%, phosphorus - up to 0.035%.
• High quality steel. Sulfur content - up to 0.025%, phosphorus - up to 0.025%.
• Special quality. Minimum presence of impurities: permissible values ​​of sulfur - up to 0.015%, phosphorus - up to 0.025%.

Classification of regular quality steel

Within the quality group, low-carbon steel of ordinary quality is divided into three more categories, designated by capital letters A, B, C.

Low-carbon steel of ordinary quality of group “A” contains alloys that differ in mechanical properties, and is found in industry in the form of sheet, profile low-carbon rolled products.

Group "B" is classified according to chemical qualities, processed under pressure under high heat, blanks are stamped and forged.

Low-carbon steels of group "B" are defined physical properties, chemical composition.

The main methods for producing low-carbon alloys

When produced, all alloys undergo the same technological stages and additional processing. The melting furnace is loaded with raw materials, charge, heated until melted, and excess impurities are removed. Additional processing depends on the specific composition of the product, the desired chemical and physical properties.

According to production technology and equipment, alloys are obtained:

• oxygen-converter smelting method;
• open-hearth method of production;
• electrothermal production method.

Oxygen-converter method

This method of producing a low-carbon alloy is named after two components of the technology. Oxygen in the air oxidizes excess carbon and impurities in the converter furnace. The converter furnace has a volume of 50–60 tons. The molten raw materials, the charge, are blown with heated oxygen under pressure. The convector walls are pear-shaped and made of metal with additional lining. The lining material chemically participates in the smelting process, reacting with the molten raw material.

Open hearth furnaces are different large size melting baths with a capacity of up to 500 tons of products. The burning of carbon and impurities also occurs with oxygen, but oxygen is obtained not only from the air. Additionally, the charge is enriched with iron ore and scrap covered with rust.

Iron oxides, participating in the process, release oxygen. Regenerator chambers preheat the combustible gas and air and alternately release the contents through the melting bath. The process takes place over 6–7 hours; upon completion, heating is stopped and deoxidizing agents are added.

Electrothermal method

This method allows you to obtain precisely specified physical and chemical properties; it is used only for the production of high-quality alloys. Large energy consumption at up to 800 kW per 1 ton of steel must be economically justified. The oven temperature reaches 1650 degrees, the bath capacity is 0.5–180 tons.

At high temperatures, sulfur and phosphorus are removed almost completely, and refractory raw materials are melted. Chemical reactions in production are similar.

The main properties of low-carbon steels

Low-carbon steel is characterized by low strength with significant toughness and ductility. The alloy is easily processed by hot deformation and welds well.

An increase in strength characteristics is achieved by carburization - saturation of the surface layers with carbon, after which the surface layers of the alloy are hardened, acquiring the necessary strength. Induction and electric furnaces are used for surface hardening of low-alloy steel. The inner, not enriched, layers remain soft, viscous, and do not lose plasticity due to the unchanged amount of carbon.

Marking of low-carbon steels and its meaning

Low-carbon steel of ordinary quality is marked with the letter value “St”, which varies according to the qualities:

• The digital value shows the amount of carbon in the alloy. Dividing the value by 100 gives the carbon content as a percentage.
• The initial letter symbols of the marking “B” or “C” indicate membership in the quality group.
• The absence of a letter designation indicates that it belongs to category “A”.
• The combination “KP” indicates a boiling composition due to deoxidation.
• The combination “PS” indicates a semi-quiet alloy; the absence of a designation indicates a calm steel.
• The letter and number combination written last on the stamp indicates the presence of impurities in the composition and their percentage.
• High-quality low-carbon alloys are not marked with the letter combination “St”.

Additionally, there is a classification by color, letter marking of alloys special purpose. For example, the marking “STZ bridge” indicates an alloy intended for use in the manufacture of bridge structures.

Scope of application

Low-carbon alloys are widely used in various areas of industry and production.

Classified by profile type the following groups manufactured products:

• Flat sheet metal. Corrugated, thick-sheet, thin-sheet, wide-strip, strip products.
• Equal and unequal corner profiles.
• Pipes, round, square, rectangular section.
• Taurus, . I-beams, wide flange, ordinary.
• Profiled metal sheet of various thicknesses.

The largest product segment is flat rolled sheets and strips. get high-strength wire, springs, springs for. Parts and workpieces are easily welded, received widespread in the construction industry, automotive industry. Body parts, axles, fuel tanks, agricultural machine frames and many other parts that are constantly encountered in everyday life.

High-carbon steel grades 55 and 60 are distinguished by high strength and hardness and are intended for the manufacture of rolling mill shafts, rods, and cable wires.

High-carbon steel grades 55, 60, 65 and 70 are characterized by high strength and hardness and are used for the manufacture of rolling mill rolls, rods, and cable wires.

High-carbon steels grades 50, 55 and 60 have low hardenability.

High-carbon steel grades 55, 60, 65, 70 are distinguished by high strength and hardness; they are used for the manufacture of rolls of rolling mills, rods, for cable wires, etc. Steel with a high manganese content is characterized by higher hardenability and higher wear resistance. Its purpose is approximately the same as steel with normal manganese content.

High-carbon steel grades 55, 60, 65, 70 are characterized by high strength and hardness and are used for the manufacture of rolling mill rolls, rods, and cable wires.

High-carbon steel grades 55, 60, 65, 70, 75, 80, 85 are distinguished by high strength and hardness and are intended for the manufacture of rolling mill shafts, rods, and cable wires.

High-carbon steel grades 55, 60 65 70 are characterized by high strength and hardness and are used for the manufacture of rolling mill rolls, rods, and cable wires.

High-carbon steel grades 55, 60, 65, 70 are distinguished by high strength and hardness and are used for the manufacture of rolls of rolling machines, rods, and for cable wires.

Welding of high-carbon steels grades VStb. 45, 50 and 60 and cast carbon steels with a carbon content of up to 0 7% is even more difficult. These steels are mainly used in castings and tool making. Their welding is possible only with preliminary and concomitant heating to a temperature of 350 - 400 C and subsequent heat treatment in heating furnaces. When welding, the rules specified for medium carbon steel must be followed. Good results are achieved by welding with narrow beads and small areas with cooling of each layer. After welding is completed, heat treatment is required.

The matrices should be made from high-carbon tool steels grades U10A, U12A or alloyed tool steels. In this case, the wear of the matrix is ​​insignificant, and its durability is high. Additional chrome plating or boriding of the working surface of the matrix has a positive effect on the stamping process.

The simplest in composition and cheapest is high-carbon steel grades U8 - U10, used for the manufacture of small non-critical magnets. Chromium steels containing from 1 5 to 3 2% Cr are of higher quality. Additions of cobalt significantly increase the magnetic properties of steel. When using these steels, their high cost should be taken into account and, if possible, replaced with cheaper steels.

The simplest in composition and cheapest is high-carbon steel grades U8 - U10, used for the manufacture of small non-critical magnets. Chromium steels containing from 1 5 to 3 2% Og are of higher quality. Additions of cobalt significantly increase the magnetic properties of steel. When using these steels, their high cost should be taken into account and, if possible, replaced with cheaper steels.

Driven disks are made of steel sheet with a thickness of 1 3 to 2 mm. Typically, medium and high carbon steel grades 50, 65, 85 are used, which allows the disk to be given the necessary spring properties.

Low-carbon steel grades 08, 10, 15, 20, 25 are used for lightly loaded parts, the manufacture of which involves welding and stamping. Medium carbon steel grades 25, 30, 40, 45, 50 are used for the manufacture of axles, shafts, gears and other parts. High-carbon steel grades 55 and 60 are used for the manufacture of spiral springs, cables and other critical parts.

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It does not contain alloying elements, including chromium, vanadium and nickel. It is worth noting that this type steel contains more than 0.6% carbon. Content carbon determines the properties of steels. Thus, with an increase in the percentage of carbon in the composition of steel, its tensile strength increases and its hardness increases, but at the same time its plastic properties decrease.

Carbon steel is more resistant to high temperatures and retains its properties when heated to 450 degrees Celsius. It perfectly withstands dynamic loads of varying severity and is able to resist corrosion. In this case, carbon steel is very light and wear-resistant. For example, carbon steel is cast iron and its products.

Different types of carbon steels are used for the production of tools, parts for boilers, pipes, turbines and other products that are used for operation under high loads.

Medium and high carbon steels have characteristic feature– form hardening structures in the weld seam and heat-affected zone, which can create a risk of brittle fracture. To obtain reliable welding seams, the steel grade is selected in accordance with the possibility of obtaining the required stable mechanical properties of welding joints.

High-carbon steels are prone to brittleness after exposure to the thermal cycle of welding and this is much more pronounced than in medium-carbon steels. This type of steel is sensitive to hot and cold cracks. Because of this, it is imperative to heat the metal being welded to a temperature of 350 - 400 degrees Celsius. After heating, it requires annealing and continues until the product being welded cools to a temperature of 20 degrees Celsius.

The production of reliable welding joints can be difficult due to the imminent danger of cold cracking and the increased sensitivity of this type of steel to stress concentrators under static and dynamic loads.

Welded structures are designed with the lowest stress concentration. The radii of transition from one section in the part being welded to another should be maximum based on permissible design considerations.

In order to increase the strength of high-carbon steel welds, smooth transitions from one metal to another should be created. For butt welding joints, it is worth removing the weld reinforcement.

In this case, special attention should be paid to the penetration of the weld seam, which has a steeper transition from the seam to the metal of the product. In cases where mechanical processing of the inner surface of the part for stripping and penetration is impossible, then combined welding should be carried out without a remaining lining.

In this case, the first weld is made by automatic argon arc welding using a non-consumable electrode without additive along the entire length of the weld, ensuring 100% uniform penetration of the metal.

Purpose and production

Their main purpose is to produce rope wire. In production they use patenting. quickly cooled until a fine-grained F+P structure (ferrite + pearlite) is obtained and immediately subjected to cold deformation - drawing. The combination of ultra-fine structure and hardening makes it possible to obtain a mechanical stress in the wire σ B > = 3000 - 5000 MPa. Due to its low toughness, structural parts made from this steel do not do. For the manufacture of bearings, chromium-alloyed (from 0.35 to 1.70% (mass) Cr) ​​steel grades ШХ4, ШХ15, ШХ15СГ, ШХ20СГ, containing 0.95-1.05% (mass) carbon (GOST 801- 78. Bearing steel. Technical conditions). Steel shot DSL (cast), DSC (chipped) and DSR (chopped) are made from high-carbon steel for shot blasting of surfaces - abrasive cleaning or hardening (GOST 11964-81. Cast iron and steel technical shot. General technical conditions). For the manufacture of springs, wire from steels KT-2 (0.86-0.91% (mass.) C) and 3K-7 (0.68-0.76% (mass.) C) is used.

Steels containing more than 0.6% carbon. weld significantly worse than medium-carbon ones, which contain from 0.25 to 0.6% carbon. High carbon steels are very prone to hardening And crack formation in the transition zone and thermally affected zone. Therefore, when welding them, a tip with a lower thermal power is used, equal to 75 l/hour per 1 mm of metal thickness. The flame should be reducing or with a slight excess of acetylene. With an oxidizing flame, increased carbon burnout occurs and the seam becomes porous. Prevention of the appearance of hardened zones and cracks is carried out by preliminary and concomitant heating to 200-250°.

The filler material is wire Sv-15, containing carbon from 0.11 to 0.18%, or Sv-15G according to GOST 2246-54. The left-hand welding method is preferred. After welding, normalization is necessary.

It is also possible to obtain deposited metal with high mechanical properties when welding these steels by using filler wire with a normal carbon content. but alloyed with chromium (0.5 - 1%), nickel (2 - 4%) and manganese (0.5 - 0.8%). When welding metal with a thickness of less than 3 mm, preheating is not performed.

Low carbon steel: composition and properties

September 15, 2016

Low carbon steel is found everywhere. Its popularity is based on physical, chemical properties oh and low cost. This alloy is widely used in industry and construction. Let's take a closer look at this type of steel.

Steel is iron enriched with carbon during the smelting process. Carbon smelting is characterized by the presence of carbon, which determines the basic properties of the metal, and impurities: phosphorus (up to 0.07%), silicon (up to 0.35%), sulfur (up to 0.06%), manganese (up to 0.8% ). Thus, low-carbon steel contains no more than 0.25% carbon. As for other additives, manganese and silicon serve deoxidation (removal of oxygen from the liquid metal, which reduces brittleness during hot deformation). But an increased percentage of sulfur can lead to cracking of the alloy during heat treatment, and phosphorus - during cold treatment.

Methods of obtaining

The production of a low-carbon alloy can be divided into several stages: loading cast iron and scrap (charge) into the furnace, thermal exposure to a state of melting, and removal of impurities from the mass. Next, steel casting or additional processing can occur: with slag or vacuum and inert gases.

To carry out such processes, three methods are used:

• Open hearth furnaces. The most common equipment. The melting process takes place over several hours, which allows laboratories to monitor the quality of the resulting composition.
• Convector ovens. Produced by purging with oxygen. It should be noted that alloys obtained in this way are not of high quality, since they contain large quantity impurities.
• Induction and electric furnaces. The production process uses slag. In this way, high-quality and specialized alloys are obtained.

Let's consider the features of the classification of alloys.

Low carbon steel can be of three types:

• Regular quality. In such alloys the sulfur content does not exceed 0.06%, phosphorus 0.07%.
• High quality. Contains: sulfur up to 0.04%, phosphorus up to 0.035%.
• High quality. Sulfur content up to 0.025%, phosphorus up to 0.025%
• Special quality. Low impurity content: sulfur up to 0.015%, phosphorus up to 0.025%.

As mentioned earlier, the fewer impurities, the better quality alloy
Low-carbon steel GOST 380-94 of ordinary quality is divided into three more groups:

• A. Determined by its mechanical properties. The form of delivery to the consumer is most often found in the form of multi-profile and sheet products.
• B. The main indicators are the chemical composition and properties. Optimal for mechanical pressure under thermal factors (forging, stamping).
• IN. For these types of alloys, the following properties are important: technical, technological, physical, chemical and, accordingly, composition.

According to the deoxidation process, steel is divided into:

• Calm. The hardening process occurs calmly. Gases are not released during this process. Shrinkage occurs in the middle of the ingot.
• Semi-calm. An intermediate type of steel between calm and boiling compositions.
• Boiling. Solidification occurs with the release of gas. Concealed type shrinkage cavity.

Basic properties

Low-carbon steel is characterized by high ductility and is easily deformed when cold or hot. Distinctive feature This alloy has good weldability. Depending on the additional elements, the properties of steel may change.
Most often, low-carbon alloys are used in construction and industry. This is due to the low price and good strength properties. This alloy is also called structural alloy. The properties of low-carbon steel are encrypted in the marking. Below we will look at its features.

Marking features

Regular low carbon steel has letter designation ST and digital. The number should be divided by 100, then the percentage of carbon will be clear. For example, ST15 (carbon 0.15%).

Let's look at the markings and decipher the notation:

• The first letters or their absence indicate belonging to one or another quality group. It can be B or C. If there is no letter, then the alloy belongs to category A.
• St stands for the word “steel”.
• The digital designation is an encrypted percentage of carbon content.
• kp, ps - denotes a boiling or semi-quiet alloy. The absence of a designation indicates that the steel is calm (sp).
• The letter designation and the number after it reveal what impurities are included in the composition and their percentage. For example, G - manganese, U - aluminum, F - vanadium.

For high-quality low-carbon steels, the marking does not include the letter designation “St9raquo;.
Color coding is also used. For example, grade 10 mild steel has White color. Become special purpose may be indicated by additional letters. For example, “К9raquo; - used in boiler making; OSV - used for the manufacture of carriage axles, etc.

Manufactured products

There are several groups of steel products:

• Sheet steel. Subtypes: thick-sheet (GOST 19903-74), thin-sheet (GOST 19904-74), wide-sheet (GOST 8200-70), strip (GOST 103-76), corrugated (GOST 8568-78)
• Angle profiles. Equal flanges (GOST 8509-93), unequal flanges (GOST 8510-86).
• Channels(GOST 8240-93).
• I-beams. Ordinary I-beams (GOST 8239-89), wide-flange I-beams (GOST 26020-83, STO ASChM 20-93).
• Pipes.
• Profiled flooring.

Secondary profiles are added to this list, which are formed through welding and machining.

Areas of application

The scope of use of low-carbon steel is quite wide and depends on the marking:

• St 0, 1, 3Gsp. Widely used in construction. For example, reinforcing wire made of low carbon steel,
• 05kp, 08, 08kp, 08yu. Good for stamping and cold drawing (high ductility). Used in the automotive industry: body parts, fuel tanks, coils, parts of welded structures.
• 10, 15. Used for parts not subject to high loads. Pipes for boilers, stampings, couplings, bolts, screws.
• 18kp. A typical application is structures that are produced using welding.
• 20, 25. Widely used for the production of fastening materials. Couplings, valve lifters, frames and other parts of agricultural machines.
• 30, 35. Lightly loaded axles, sprockets, gears, etc.
• 40, 45, 50. Parts experiencing medium loads. For example, crankshafts, friction discs.
• 60-85. Parts subject to high loads. These could be rails for railway, wheels for cranes, springs, washers.

As you can see, the product range is extensive - it’s not just low-carbon steel wire. These are also parts of complex mechanisms.

Low alloy and low carbon steel: differences

To improve any characteristics of the alloy, alloying elements are added.
Steels that contain a low amount of carbon (up to a quarter of a percent) and alloying additives (total percentage - up to 4%) are called low-alloy. Such rolled products retain high welding qualities, but at the same time strengthen different properties. For example, strength, anti-corrosion characteristics and so on. As a rule, both types are used in welded structures that must withstand temperature Range from minus 40 to plus 450 degrees Celsius.

Welding Features

Welding low-carbon steels has high performance. The type of welding, electrodes and their thickness are selected based on the following technical data:

• The connection must be firmly fastened.
• There should be no seam defects.
• The chemical composition of the seam must be carried out in accordance with the standards specified in GOST.
• Welded joints must comply with operating conditions (resistance to vibration, mechanical stress, temperature conditions).

Can be used different kinds welding from gas to medium welding carbon dioxide consumable electrode. When selecting, take into account the high fusibility of low-carbon and low-alloy alloys.

As for the specific scope of application, low-carbon rolled products are used in construction and mechanical engineering.
The steel grade is selected based on the required output physical and chemical properties. The presence of alloying elements can improve some properties (resistance to corrosion, temperature changes), but also worsen others. Good weldability is another advantage of such alloys.

So, we found out what products made from low-carbon and low-alloy steel are.

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High carbon steel - is it beneficial to have a lot of impurities in the alloy?

High carbon steel has found its application in many areas because it has a number of advantages. However, its use is not always advisable, so it is very important to know the properties and features of this alloy. These are the ones that will be discussed below.

1. What steels are called high carbon?
2. Properties and applications of high carbon steel
3. Marking for high carbon steels

1 What steels are called high-carbon?

First, you should generally understand what steel is. So, it is an alloy of carbon and iron, as well as other alloying elements. Moreover, the content of the first varies from 0.02% to 2.14%, and depending on its amount, steels are divided into low-, medium- and high-carbon. What about the latter, in this case, as is already clear from the name, in the alloy increased amount carbon, this is more than 0.6%. This composition affects performance characteristics.

High-carbon steel, the mechanical properties of which we will consider in more detail below, is quite problematic to weld, and all because of the material’s tendency to such defects as hardened zones and cracks in the heat-affected area. In this regard, it is necessary to use tips with low thermal power. What about the flame, it must be restorative, because an oxidizing one will lead to excessive burning of carbon, and this will contribute to increased porosity of the seam.

In order to prevent the above-described defects, the material should be heated to a temperature of 200–250 °C.

2 Properties and applications of high carbon steel

Let's consider how carbon content affects the properties of steels. So, with an increase in this element in the structure, the proportion of cementite increases, while the amount of ferrite, on the contrary, decreases. In this regard, the material becomes less plastic. What about characteristics such as hardness and strength, such a change has a positive effect on them. But even here, not everything is so simple, maximum strength characteristics will be achieved at a carbon value of 1%, but if its amount increases further, then a network of secondary cementite will appear in the structure, and the strength will begin to decrease.

Now let’s look at the impact toughness of such steels; it decreases, but the electrical resistance and temperature range for the transition of the material from ductile to brittle fracture becomes higher. In addition, it is worth noting a deterioration in casting properties and weldability, and operations such as cutting and pressure processing of the material will become more problematic. In this regard, these steel grades are not entirely suitable for welding, although this operation cannot be avoided, especially when we're talking about O repair work. They are much more often used for stamping parts. In addition, wire made from this particular type of material is also widely used. They are also used in the foundry industry.

3 Markings for high carbon steels

Of course, to know what the influence of certain chemical elements on the properties of alloys is very important, but how can one determine its composition? After all, it plays a significant role and affects the properties, quality, and tensile strength of the material, and if it is chosen incorrectly, then sometimes the consequences can be irreversible. So, for example, if the tensile strength of any structural element is exceeded, it collapses.

This is precisely why there is a marking that has letters and numbers and is applied with a special indelible paint. Moreover, according to this code You can not only read the amount of alloying elements, but also find out additional information, such as the quality of the metal, its degree of deoxidation, etc. This will be discussed in this paragraph.

So, in addition to carbon, the properties of steel are also affected by the presence of manganese. It promotes hardenability, improves the strength characteristics of the material and its wear resistance. In this regard, it is present in almost every type of steel, and if its content is more than 0.8%, then in the marking of such material the letter “G” will immediately follow the digital designation indicating the amount of carbon. If we are talking about tool steels with a carbon content of more than 0.75%, then their code begins with the capital letter “U”, followed by the percentage of C in tenths. So, U9 means that they are talking about carbon tool steel. which contains about 0.9% carbon.

In addition, high-carbon steels of different grades have some other designations. For example, if the alloy is High Quality, then the letter “A” must be placed at the end of the cipher, but especially high-quality ones are designated as “Ш”. According to the degree of deoxidation, these materials are divided into boiling, semi-quiet and calm, their designation is “kp”, “ps” and “sp”, respectively.

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Such products are characterized by a high content of the chemical element C. Its share in the iron + carbon alloy is at least 0.55%. What properties it gives to steel, its grade - all this will be the topic of conversation.

There is no separate standard for high-carbon steels. This metal is just one type of alloy of iron and carbon. It received its name due to the increased content of the element C (6th position in periodic table). The classification of all steels, as well as marking, is quite complex.

Detailed information on all carbon metals can be found in various GOSTs. As a rule, first of all, specialists turn to standards such as No. 1050 of 1988 and No. 380 of 2005, in which footnotes to other regulatory documents are indicated for individual positions.

Features of high-carbon steels

• Percentage content of chemical elements: C – (0.55 – 1.7); Mn – (0.3 – 0.9).
• Insufficient viscosity. For this reason, structural products (parts) are not produced from high-carbon steels.
• Increased strength and wear resistance. But this is only if the carbon content does not exceed 0.8 - 0.9%. A further increase in the fraction of C sharply reduces the numerical values ​​of these characteristics.
• Poor weldability because high temperatures initiate the formation of cracks in the metal, pores, and the appearance of hardened segments due to intense carbon burnout. Therefore, it is necessary to preheat the working area (up to 225 ± 25 ºС).
• High production costs. It is this, as well as individual properties, that limit the scope of application of such steels.

What is produced

• Steel shot used for abrasive processing of materials - DSR (chopped), DSC (chipped) and DSL (cast).
• Rope wire.
• Springs.
• various types.

Basically, all parts made of high-carbon steels are made by stamping, since pressure techniques, due to the low ductility of the material, are ineffective.

The tables below will certainly help the reader understand what grade of high-carbon steel he needs for specific purposes.

All brands often have additional symbols in their designation, which are placed at the end. There are quite a few of them, so only the most common ones.

Due to its strength characteristics and affordable price Carbon steel is a very common alloy. Its main elements are iron and carbon with a minimum of drops. Carbon steel is used to produce various engineering products, pipeline and boiler parts, and tools. Alloys are also widely used in construction.

Main characteristics

Depending on their main purpose, carbon steels are divided into instrumental and structural; there are practically no alloying elements in their composition. They also differ from ordinary steel alloys in that they contain significantly fewer basic impurities: manganese, magnesium, silicon. The content of the main element - carbon - varies quite widely. High-carbon steel contains 0.6−2% C, medium-carbon steel - 0.3−0.6%, low-carbon steel - up to 0.25%.

The main element determines the properties and structure. In the internal structure of alloys with less than 0.8% C (hypoeutectoid steel) there is predominantly pearlite and ferrite, and with an increase in the concentration of the main element, secondary cementite is formed.

The presented steels with a predominant ferritic structure are highly ductile and have low strength. If the structure is dominated by cementite, the metal is characterized by high strength, but also great fragility. When the C content increases to 0.8−1%, strength and hardness increase, but viscosity and ductility greatly deteriorate.

The quantitative carbon content affects the technological characteristics, in particular, weldability, ease of cutting and pressure.

• Low-carbon steels are used to make parts and structures that are not intended for significant loads.
• The characteristics of medium-carbon steels make them the main structural material used in the production of structures and parts for transport and general engineering.
• High-carbon alloys are optimal for the manufacture of parts that must have increased wear resistance in the production of measuring and impact tools.

The metal, like other steel alloys, contains impurities:

• silicon;
• phosphorus;
• manganese;
• nitrogen;
• sulfur;
• hydrogen;
• oxygen.

Silicon and manganese are useful impurities that are introduced into the composition at the smelting stage for deoxidation. Phosphorus and sulfur are harmful impurities, worsening the quality characteristics of the alloy.

It is believed that alloying and carbonaceous species are incompatible, however, in order to improve their technological and physical-mechanical characteristics, microalloying can be performed by adding various additives:

• boron;
• titanium;
• zirconium;
• rare earth elements.

With their help, it will not be possible to turn metal into stainless steel, but it will significantly improve the properties.

Classification by degree of deoxidation

The division into types is influenced, in particular, by the degree of deoxidation. Depending on this parameter, our alloys are divided into semi-calm, calm and boiling.

Quiet steels have a more uniform internal structure, whose deoxidation is achieved by adding to the molten aluminum, ferrosilicon and ferromanganese metal. Due to the fact that the alloys of our category are completely deoxidized in the furnace, they do not contain ferrous oxide. Residual aluminum, which inhibits grain growth, provides a fine-grained structure. This and the almost absolute absence of dissolved gases makes it possible to obtain high-quality metal for the manufacture of the most critical parts and structures. Along with the advantages, quiet alloys have a big disadvantage - rather expensive smelting.

There are cheaper, although lower quality, carbon alloys, the smelting of which uses a minimum of special additives. In the structure of such a metal due to the fact that the deoxidation process in the oven was not completed, there are dissolved gases that negatively affect the characteristics. Nitrogen, for example, has a bad effect on weldability and provokes the formation of cracks in the weld area. Developed segregation in the structure of alloys leads to the fact that rolled metal products made from them are characterized by heterogeneity in structure and mechanical characteristics.

Semi-quiet steels have an intermediate position in properties and degree of deoxidation. Before pouring into molds, a small amount of deoxidizers is introduced into their composition, thanks to which solidification of the metal occurs practically without boiling, but the release of gases in it continues. The result is a casting whose structure contains fewer gas bubbles than boiling steels. These internal pores are welded almost completely during subsequent rolling of the metal.

Most semi-mild carbon steels are used as structural materials.

Production and division by quality

Carbon steels are produced using different technologies. There are:

• high-quality carbon steels;
• high quality steel alloys;
• carbon steel alloys of ordinary quality.

Alloys of ordinary quality are obtained in open-hearth furnaces, and large ingots are formed from them. Melting equipment used to produce such steels includes, in particular, oxygen converters. Compared to high-quality steel alloys, the metal may contain many harmful impurities, which affects the characteristics and cost of production.

Formed and frozen ingots are rolled hot or cold. Hot rolling produces long and shaped products, thin and thick sheet metal, and wide metal strips. Cold rolling produces thin sheet metal.

To produce high-quality and high-quality steel, open hearth furnaces and converters are used, as well as melting furnaces that run on electricity.

GOST imposes strict requirements on the composition, namely the presence of harmful and non-metallic impurities in the structure. High quality steels should have no more than 0.04% sulfur and no more than 0.035% phosphorus. High-quality and high-quality steel alloys, due to strict requirements for the smelting method and characteristics, have increased structural purity.

Application and labeling

Tool alloys containing 0.65−1.32% C are used to make various tools. To improve the mechanical properties of tools, the manufacturing material is hardened.

Structural alloys are used to make parts for various equipment, structural elements for construction and engineering purposes, fasteners, etc. Made from structural steel carbon wire, which is used in everyday life, in the production of fasteners, in construction, for the manufacture of springs. After cementation structural alloys They are successfully used in the production of parts that are subject to severe surface wear during operation and experience high dynamic loads.

The markings indicate chemical composition alloy and its category. In the designation of carbon steel of ordinary quality there are the letters “st”. GOST stipulates seven conventional brand numbers (0−6), also indicated in the designation. The degree of deoxidation is indicated by the letters “kp”, “ps”, “sp”, placed at the end of the marking. Grades of high-quality and high-quality steels are designated by numbers that indicate the C content in the alloy in hundredths of a percent.

The fact that the alloy is instrumental can be understood by the letter “U” at the beginning of the marking. The number following this letter indicates the C content in tenths of a percent. The letter “A”, if present in the designation of tool steel, indicates improved quality characteristics of the alloy.

Steels with a higher carbon content may be less prone to forming low-ductility structures. When exposed to structural and welding stresses, a metal of low ductility can collapse. This is facilitated by the presence of diffusion hydrogen in it and its welding seam. To prevent the appearance of cold cracks, methods are used to eliminate the factors that contribute to the appearance of such defects.

In addition to carbon, ordinary carbon steels also contain other elements: up to 1.65% manganese; up to 005% sulfur; up to 0.04% phosphorus; up to 0.60% silicon and up to 0.60% copper.
Mass media
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Carbon steels can be classified from various points of view, for example, by the method of deoxidation. Of course, the method of deoxidation affects the characteristics and properties of steel. However, changes in carbon content have the greatest impact on the mechanical properties of steel - with increasing carbon content, its hardness and strength increase. Therefore, steels are usually grouped according to their carbon content. Typically, carbon steels contain up to 2% of all alloying elements in total and are in turn divided into:

• low carbon steels;
• medium carbon steels and
• high carbon steels.

Carbon steels are the main products of the ferrous metallurgy - they make up more than 80% of its output. The main metal material in the industry is carbon steel.

For carbon steels, the following standards are most often used:

• . Carbon steel of ordinary quality
• GOST 1050-88. Carbon steel, high-quality structural

Low carbon steels

Low-carbon steels contain carbon up to 0.25%. The largest category of this class of steels is flat rolled products - sheets and strips, usually in the cold-rolled or annealed state. The carbon content to enhance the hot workability and cold drawing ability of these steels is usually very low (less than 0.10%) with manganese content up to 0.40%. These low-carbon steels are used for the manufacture of car bodies, tin and wire products.

Low-carbon steels with a carbon content of 0.10 to 0.25% have increased strength and hardness, but lower plastic deformability compared to low-carbon steels with the lowest carbon content.

These steels are often used in combination with a carburization process. Typical applications for case-hardened steels are parts with high wear resistance requirements, but without the need to increase the strength of the core of the part, such as small shafts or gears.

Rolled profiles made of structural steel with a carbon content of about 0.25% and up to 1.5% manganese and aluminum are used in conditions where increased viscosity of the material is required. When steel is used for stamping, forging, seamless pipe or boiler plate, no aluminum is added.

An important category of these steels are low-alloy free-range steels with a carbon content of up to 0.15% and manganese - up to 1.2% with a minimum of silicon and a sulfur content of up to 0.35%, as well as with or without lead up to 0.30%. These steels are intended for automatic mass production of parts from them that are not subject to severe mechanical and climatic influences. If the product requires high ductility and toughness, as well as corrosion resistance, then these steels are not suitable for it.

Medium carbon steels

Medium carbon steels contain 0.30-0.55% carbon and 0.60-1.65% manganese. They are used where high mechanical properties are required. These steels are usually strengthened by heat treatment or work hardening. Steels from this group with reduced carbon and manganese content are widely used for certain types of parts produced by cold plastic deformation. This requires the prior application of annealing, normalizing or hardening and tempering. Steels with higher carbon content are often drawn to specified mechanical properties for use without heat treatment.

All these steels can be forged. The choice of steel depends on the dimensions of the product and the mechanical properties that it must provide after heat treatment. These steels are usually produced as mild steels and are widely used in mechanical engineering. Lead and sulfur are also added to these steels if mass mechanical processing is necessary, as well as aluminum to refine the grain and increase toughness. Steels with a carbon content of 0.40-0.60% are used for the manufacture of railway rails, carriage wheels and axles, and tires for locomotives.

High carbon steels

High-carbon steels containing 0.55-1.00% carbon and 0.30-0.90% manganese have more limited use than medium-carbon steels. The fact is that these steels are more expensive to produce, have low ductility and, therefore, are difficult to hot work, and are also difficult to weld. High-carbon steels are used in the production of springs, in the manufacture of various cutting tools, including components for earthmoving and agricultural machinery, as well as high-tensile wire – wherever greater wear resistance and higher strength are required than lower carbon steels can provide.