High carbon steel. Carbon steels: features, classification, processing and scope

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

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

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

High-carbon steel of grades 55, 60, 65, 70 is distinguished by high strength and hardness, it is used for the manufacture of rolls of rolling mills, rods, for wire cables, etc. high content manganese is characterized by higher hardenability, higher wear resistance. Its purpose is approximately the same as steel with a 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 rolls of rolling mills, rods, for wire ropes.

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

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

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 wire ropes.

Welding of high-carbon steel 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 cast parts and in the manufacture of tools. 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 for medium carbon steel must be observed. Good results are achieved when welding with narrow beads and small areas with cooling of each layer. After welding is completed, heat treatment is required.

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

The simplest in composition and the cheapest is high-carbon steel grades U8 - U10, used for the manufacture of small irresponsible magnets. Chromium steels containing from 15 to 32% Cr are of higher quality. Additions of cobalt significantly increase magnetic properties become. When using these steels, one should take into account their high cost and, if possible, replace them with cheaper steels.

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

Driven discs are made from steel sheet thickness from 1 3 to 2 mm. Usually medium and high carbon steel grades 50, 65, 85 are used, which makes it possible to give the disk the necessary spring properties.

Mild steel grades 08, 10, 15, 20, 25 are used for lightly loaded parts, the manufacture of which is associated with 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, 60 are used for the manufacture of coil springs, cables and other critical parts.

Pages: 9ensp;9ensp;1

It does not contain alloying elements, among which are chromium, vanadium and nickel. It is worth noting that this species steel contains carbon over 0.6%. 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 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 perceives dynamic loads of varying severity and is able to resist corrosion. In this case, carbon steel is very light and resistant to wear. An example of 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 to operate under high loads.

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

High carbon steels are prone to brittleness after exposure to the thermal cycle of welding and is much more pronounced than in medium carbon steels. Steels of this type are 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 carry it out until the workpiece to be welded cools down to a temperature of 20 degrees Celsius.

The manufacture of reliable welded joints can be difficult due to the impending danger of cold cracking and the increased sensitivity of steels of this type to stress concentrators under static and dynamic loads.

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

In order to increase the strength of high-carbon steel welds, it is necessary to create smooth transitions from one to another weld metal. For a butt weld, it is worth removing the reinforcement welding seam.

In this case, special attention should be paid to the penetration of the weld, which has a steeper transition from the weld to the metal of the product. When machining inner surface parts for cleaning and penetration is not possible, then combined welding should be carried out without the remaining backing.

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

Purpose and production

Their main purpose is to obtain rope wire. Used in the manufacture patenting. quickly cooled to obtain a fine-grained structure F + P (ferrite + perlite) and immediately subjected to cold deformation - drawing. The combination of ultrafine structure and work hardening makes it possible to obtain a mechanical stress in the wire σ B > = 3000 - 5000 MPa. Due to the low viscosity, structural parts made of this steel do not do. For the manufacture of bearings, chromium-alloyed (from 0.35 to 1.70% (wt.) Cr) steel grades ShKh4, ShKh15, ShKh15SG, ShKh20SG containing 0.95-1.05% (wt.) carbon (GOST 801- 78. Bearing steel. Specifications). High-carbon steel is used to make steel shot DSL (cast), DSK (chopped) and DSR (chopped) for shot blasting of surfaces - abrasive cleaning or hardening (GOST 11964-81. Cast iron and technical steel shot. General specifications). For the manufacture of springs, wire from steels KT-2 (0.86-0.91% (wt.) C) and 3K-7 (0.68-0.76% (wt.) C) is used.

Steels containing more than 0.6% carbon. are welded much worse than medium-carbon ones, in which carbon contains from 0.25 to 0.6%. High carbon steels are very prone to hardening and cracking in the transition zone and the heat affected zone. Therefore, when welding them, a tip with a lower thermal power is used, equal to 75 l / h 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 is porous. Prevention of the appearance of hardened zones and cracks is carried out by preliminary and concomitant heating up to 200-250 °.

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

It is also possible to obtain a weld metal with high mechanical properties when welding these steels by using a 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 ubiquitous. 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% ). So, mild steel contains no more than 0.25% carbon. As for other additives, manganese and silicon serve to deoxidize (remove 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, phosphorus - during cold treatment.

How to get

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

Three methods are used to execute such processes:

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

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%.
quality. The composition contains: sulfur up to 0.04%, phosphorus up to 0.035%.
High quality. Sulfur content up to 0.025%, phosphorus content up to 0.025%
Special quality. Low content of impurities: sulfur up to 0.015%, phosphorus - up to 0.025%.

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

BUT. determined by its mechanical properties. The form of delivery to the consumer is most often found in the form of multi-section and sheet metal.
B. Basic indicators - chemical composition and properties. Optimal for mechanical action by pressure under a thermal factor (forging, stamping).
AT. For these types of alloys, the following properties are important: technical, technological, physical, chemical and, accordingly, composition.

According to the process of deoxidation, steel is divided into:

Calm. The curing process is going smoothly. No gases are released during this process. Shrinkage occurs in the middle of the ingot.
Semi-calm. An intermediate view of steel between calm and boiling compositions.
Boiling. Solidification occurs with the release of gas. Shrinkage shell of hidden type.

Basic properties

Low-carbon steel is highly ductile, easily deformed in a cold state and in a hot state. hallmark such an alloy is a good weldability. Depending on the additional elements, the properties of the steel may vary.
Most often, low-carbon alloys are used in construction and industry. This is due to the low price and good strength properties. Such an alloy is also called structural. The properties of low carbon steel are encrypted in the marking. Below we will consider its features.

Marking features

Ordinary mild steel has the letter designation CT and digital. The number should be divided by 100, then the percentage of carbon will be clear. For example, CT15 (carbon 0.15%).

Consider the marking and decipher the notation:

The first letters or their absence indicates belonging to a particular quality group. It can be B or C. If there is no letter, then the alloy belongs to category A.
St means the word "steel9raquo;.
The digital designation is the encrypted percentage of carbon.
kp, ps - denotes a boiling or semi-calm alloy. The absence of a designation indicates that the steel is calm (cn).
The letter designation and the number after it reveal which impurities are included in the composition, and their percentage. For example, G - manganese, Yu - aluminum, F - vanadium.

For high-quality low-carbon steels, the lettering “St9raquo;” is not put in the marking.
Also applies color designation. For example, grade 10 mild steel has White color. Become special purpose may be denoted by additional letters. For example, "K9raquo; - used in boiler building; OSV - used for the manufacture of wagon axles, etc.

Manufactured products

There are several groups of steel products:

Sheet steel. Subspecies: thick sheet (GOST 19903-74), thin sheet (GOST 19904-74), broadband (GOST 8200-70), strip (GOST 103-76), corrugated (GOST 8568-78)
Corner profiles. Equal-shelf (GOST 8509-93), unequal-shelf (GOST 8510-86).
Channels(GOST 8240-93).
I-beams. Ordinary I-beams (GOST 8239-89), Wide-shelf I-beams (GOST 26020-83, STO ASCHM 20-93).
Pipes.
Profiled flooring.

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

Applications

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

St 0, 1, 3Gsp. Wide application in construction. For example, low carbon steel reinforcing wire,
05kp, 08, 08kp, 08y. Good for stamping and cold drawing (high plasticity). Used in the automotive industry: body parts, fuel tanks, coils, parts of welded structures.
10, 15. They are used for parts that are not subjected to high loads. Boiler pipes, stampings, couplings, bolts, screws.
18kp. A typical application is structures that are produced by welding.
20, 25. Widely used for the production of fasteners. Couplings, valve tappets, 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 subjected to high stress. It could be rails for railway, wheels for cranes, springs, washers.

As you can see, the product range is extensive - it is not only low-carbon steel wire. It is also the details 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 (a total percentage of up to 4%) in the cheba are called low-alloyed. Such rolled products retain high weldability, but at the same time, different properties are enhanced. For example, strength, anti-corrosion performance and so on. As a rule, both types are used in welded structures, which must withstand a temperature range from minus 40 to plus 450 degrees Celsius.

Welding Features

Welding of 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 the operating conditions (resistance to vibrations, mechanical stress, temperature conditions).

Can be used different kinds welding from gas to welding in 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 steel is used in construction and engineering.
The steel grade is selected on the basis of the required physical and chemical properties at the output. The presence of alloying elements can improve some properties (resistance to corrosion, temperature extremes), but also worsen others. Good weldability is another advantage of such alloys.

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

Our ancestors slept differently than we do. What are we doing wrong? It's hard to believe, but scientists and many historians are inclined to believe that modern man sleeps quite differently from his ancient ancestors. Initially.

These 10 little things a man always notices in a woman Do you think your man knows nothing about female psychology? This is not true. Not a single trifle will hide from the gaze of a partner who loves you. And here are 10 things.

7 Body Parts You Shouldn't Touch Think of your body as a temple: you can use it, but there are some sacred places that you shouldn't touch. Display research.

Top 10 Broken Stars It turns out that sometimes even the loudest glory ends in failure, as is the case with these celebrities.

What is it like to be a virgin at 30? What, I wonder, women who did not have sex until almost reaching middle age.

How to look younger: the best haircuts for those over 30, 40, 50, 60 Girls in their 20s don't worry about the shape and length of their hair. It seems that youth was created for experiments on appearance and bold curls. However, already

High carbon steel - is it good 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 far from always expedient, so it is very important to know the properties and features of this alloy. It is about them that will be discussed below.

What are high carbon steels?
Properties and scope of high carbon steel
Marking for high carbon steels

1 What are high carbon steels?

The first thing to do is to understand what steel is. So, it is an alloy of carbon and iron, as well as other alloying elements. Moreover, the content of the former ranges from 0.02% to 2.14%, and depending on its amount, steels are divided into low-, medium- and high-carbon steels. As for the latter, in this case, as it already becomes clear from the name, there is an increased amount of carbon in the alloy, this is more than 0.6%. This composition affects performance.

High-carbon steel, the mechanical properties of which we will discuss in more detail below, is rather problematic to weld, and all because of the tendency of the material to such defects as hardened zones and cracks in the heat-affected region. In this regard, it is necessary to use tips with low thermal power. As for the flame, it should be reducing, because the oxidizing one will lead to excessive carbon burnout, and this will contribute to the 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 scope of high carbon steel

Consider how the carbon content affects the properties of steels. So, with an increase in this element, the proportion of cementite in the structure increases, while the amount of ferrite, on the contrary, decreases. As a result, the material becomes less ductile. As for such characteristics as hardness and strength, such a change affects them in a positive way. But even here everything is not so simple, the 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 dwell on the impact strength of such steels, it decreases, but the electrical resistance and the temperature interval for the transition of the material from ductile to brittle fracture becomes higher. In addition, it is worth noting the deterioration of the casting properties, weldability, and operations such as cutting and forming 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 are talking about repair work. They are much more often used for stamping parts. Besides, wide use I also found a wire made of this type of material. They are also used in the foundry industry.

3 Marking for high carbon steels

Of course, to know what the impact of certain chemical elements on the properties of alloys is very important, but how to determine its composition? After all, it is he who plays a significant role and affects the property, quality, as well as the tensile strength of the material, and if it is not properly selected, then sometimes the consequences can be irreversible. So, for example, if the tensile strength of any structural element is exceeded, it collapses.

It is for this that there is a marking that has letter and number designations and is applied with a special indelible paint. Moreover, using this code, you can not only read the number of alloying elements, but also find out more 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 presence of manganese also affects the properties of steel. 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 a material, immediately after the digital designation indicating the amount of carbon, the letter “G” will follow. If we are talking about tool steels with a carbon content of more than 0.75%, then their code begins with a capital letter "U", followed by a percentage of C in tenths. So, U9 means that they are talking about carbon tool steel. in which 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” is necessarily put 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-calm and calm, their designation in the marking "kp", "ps" and "sp", respectively.

Pipe bender manual TR and other brands - we consider the types of this device

In this article, we will look at various mechanical pipe benders that can be used by hand, using only muscle.

Kinds welding machines– overview of popular models

The article will tell you what special equipment it makes sense to purchase if you plan to work on.

Low carbon steel -- Carbon steel with up to 0.25% carbon (C). Low-carbon steel grades 20, VMStZsp, S75, APS 10M4, 18X1PMF have good resistance to static hydrogen fatigue.

Low-carbon steel grades 08, 08kp, 08ps are soft steels, most often used in the annealed state for the manufacture of parts by cold stamping - deep drawing. Steel grades 10, 15, 20, 25 are usually used as carburizing, and high-carbon steels 60, 65, 70, 75, 80 and 85 are mainly used for the manufacture of springs, springs, high-strength wire and other products with high elasticity and wear resistance. Medium carbon steels 30 35 40 45 50 and similar steels with a high content of manganese ZOG, 40G, 50G are used for the manufacture of a wide variety of machine parts.

Medium carbon steel - carbon steel with a carbon content of 0.25 ... 0.6%. Medium carbon structural steel grades 30 - 55 are used after normalization, improvement, hardening with low tempering, surface hardening for the manufacture of a wide range of machine building parts. Carbon structural steel of high strength, wear resistance, with high elastic properties of grades 60, 60G, 65, 65G, 70, 70G, 80 and 85 is used after hardening and tempering, normalization and tempering, surface hardening for the manufacture of parts operating in friction conditions at high static and vibration loads.

Steel 40G belongs to the group of medium-carbon structural steels with high manganese content and has increased strength. The presence of up to 10% Mn and up to 037% Si ensures good deoxidation and smooth casting of steel. Steel acquires high strength properties after hardening and tempering.

Steel 50G belongs to the group of medium-carbon structural steels with high manganese content, has high strength and high elastic properties. It is applied after heat treatment- hardening and tempering, in some cases - after normalization.

Steel 40 N refers to medium carbon structural steels of high strength and toughness. The presence of chromium and nickel gives the steel high strength properties, increased toughness and good technological properties. Steel has deep hardenability.

High-carbon steel - steel with a carbon content of more than 0.6% (up to 2%). Their main purpose is to obtain rope wire. In the manufacture, patenting is used, it is quickly cooled to obtain a fine-grained F + P structure (ferrite + perlite) and immediately subjected to cold deformation - drawing. The combination of ultrafine structure and work hardening makes it possible to obtain a mechanical stress in the wire = 3000 - 5000 MPa. Due to the low viscosity, structural parts are not made from this steel. For the manufacture of bearings, chromium-alloyed (from 0.35 to 1.70% (wt.) Cr) steel grades ShKh4, ShKh15, ShKh15SG, ShKh20SG containing 0.95-1.05% (wt.) carbon (GOST 801- 78. Bearing steel. Specifications). High-carbon steel is used to make steel shot DSL (cast), DSC (chopped) and DSR (chopped) for shot blasting of surfaces - abrasive cleaning or hardening (GOST 11964-81. Cast iron and technical steel shot. General specifications). For the manufacture of springs, wire from steels KT-2 (0.86-0.91% (wt.) C) and 3K-7 (0.68-0.76% (wt.) C) is used.

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

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

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

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

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

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

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 wire ropes. Welding of high-carbon steel 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 cast parts and in the manufacture of tools. 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 for medium carbon steel must be observed. Good results are achieved when welding with narrow beads and small areas with cooling of each layer. After welding is completed, heat treatment is required.

Carbon steels. Classification and marking of carbon steels. Tool and structural carbon steels

1

2

Consider how the carbon content affects the properties of steels. So, with an increase in this element, the proportion of cementite in the structure increases, while the amount of ferrite, on the contrary, decreases. As a result, the material becomes less ductile. As for such characteristics as hardness and strength, such a change affects them in a positive way. But even here, not everything is so simple, the maximum strength characteristics will be achieved at a carbon value of 1%, but if its amount still increases, then a network of secondary cementite will appear in the structure, and the strength will begin to decrease.

Now let's dwell on the impact strength of such steels, it decreases, but the electrical resistance and the temperature interval for the transition of the material from ductile to brittle fracture becomes higher. In addition, it is worth noting the deterioration of the casting properties, weldability, and operations such as cutting and forming 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 it comes to repair work. They are much more often used for. In addition, wire made from this type of material has also become widespread. They are also used in the foundry industry.

3

Of course, it is very important to know what effect certain chemical elements have on the properties of alloys, but how can one determine its composition? After all, it is he who plays a significant role and affects the property, quality, as well as the tensile strength of the material, and if it is not properly selected, then sometimes the consequences can be irreversible. So, for example, if the tensile strength of any structural element is exceeded, it collapses.

It is for this that there is a marking that has letter and number designations and is applied with a special indelible paint. Moreover, using this code, you can not only read the number of alloying elements, but also find out more 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 presence of manganese also affects the properties of steel. 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 a material, immediately after the digital designation indicating the amount of carbon, the letter "G" will follow. If we are talking about with a carbon content of more than 0.75%, then their code begins with a capital letter "Y", followed by a percentage of C in tenths. So, U9 means that they are talking about carbon tool steel, in which there is about 0.9% carbon.

In addition, high-carbon steels of different grades have some other designations. For example, if the alloy is of high quality, then the letter "A" is necessarily put 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-calm and calm, their designation in the marking "kp", "ps" and "sp", respectively.

High carbon steel

High carbon steel - steel with a carbon content over 0.6%(up to 2%).

Purpose and production

Them main purpose is the receipt of a rope wire. Used in the manufacture patenting, quickly cooled to obtain a fine-grained F + P structure (ferrite + perlite) and immediately subjected to cold deformation - drawing. The combination of ultrafine structure and work hardening makes it possible to obtain a mechanical stress in the wire = 3000 - 5000 MPa. Due to the low viscosity, structural parts made of this steel do not do. For the manufacture of bearings, chromium-alloyed (from 0.35 to 1.70% (wt.) Cr) steel grades ShKh4, ShKh15, ShKh15SG, ShKh20SG containing 0.95-1.05% (wt.) carbon (GOST 801- 78. Bearing steel. Specifications). High-carbon steel is used to make steel shot DSL (cast), DSC (chopped) and DSR (chopped) for shot blasting of surfaces - abrasive cleaning or hardening (GOST 11964-81. Cast iron and technical steel shot. General specifications). For the manufacture of springs, wire from steels KT-2 (0.86-0.91% (wt.) C) and 3K-7 (0.68-0.76% (wt.) C) is used.

Welding

Wikimedia Foundation. 2010 .

See what "High carbon steel" is in other dictionaries:

HIGH CARBON STEEL- unalloyed steel containing more than 0.6% C. see Carbon steel ... Metallurgical Dictionary

High carbon steel- unalloyed steel containing more than 0.6% C ... encyclopedic Dictionary in metallurgy

Steel- (Steel) Definition of steel, production and processing of steel, properties of steels Information on the definition of steel, production and processing of steel, classification and properties of steels Contents Contents Classification Characteristics of steel Varieties ... ... Encyclopedia of the investor

This term has other meanings, see Steel (meanings). Steel Phases of iron-carbon alloys Ferrite (solid solution of interstitial C in α iron with a body-centered cubic lattice) Austenite (solid solution of interstitial C in γ ... ... Wikipedia

This term has other meanings, see Damascus (meanings). Blade (knife), imitation of Damascus steel Damascus (Damascus steel) view of steel with visible ... Wikipedia

It is a low alloy, medium or high carbon steel with a very high yield strength. This allows spring steel products to return to their original shape despite significant bending and twisting. Most ... ... Wikipedia

This article or section describes the situation in relation to only one region (USSR/Russia). You can help Wikipedia by adding information for other countries and regions... Wikipedia

Phases of iron-carbon alloys Ferrite (solid solution of interstitial C in α iron with a body-centered cubic lattice) Austenite (solid solution of interstitial C in γ iron with a face-centered cubic lattice) Cementite (iron carbide; Fe3C ... Wikipedia

Most manufacturing uses mild steel to some extent. Construction, mechanical engineering, machine tool building - this is an incomplete list of industries where it is actively used.

Composition according to GOST

Steel is an alloy of iron with carbon, the percentage of the latter should not exceed 2.14%. Anything above this value is already cast iron. Low-carbon steel is characterized by a low carbon content, which leaves its mark on both mechanical and technological properties.

There are several standards that govern the composition of carbon alloys. Among them, GOST 380-2005 and GOST 1050-90 are the most in demand. According to them, low-carbon steel can be called, which includes:

Carbon (up to 0.25%). It allows you to thermally harden steel, as a result of which the hardness and tensile strength of the metal can increase several times.
Silicon (up to 0.35%) It improves mechanical properties, especially impact strength and strength. Also, an increase in silicon in the alloy has a positive effect on weldability.
Manganese (up to 0.8%) belongs to the group of useful impurities. In its molecular structure, it is similar to oxygen and actively enters with it. chemical bond which prevents the formation of iron oxide. Steel alloyed with manganese is more homogeneous in composition, better able to cope with dynamic loads, and becomes more susceptible to thermal hardening.
Sulfur (up to 0.06%) is a harmful impurity. Makes metal red-brittle, complicates pressure treatment: forging, rolling, etc. Reduces the density of the weld. Increases temper brittleness.
Phosphorus (up to 0.08%) is responsible for the appearance of cold brittleness. Distorts the crystal structure of steel. Reduces its impact strength. Degrades the strength and endurance of the metal. But phosphorus is not always harmful impurity. In some cases, its addition is justified, because. it increases the ductility of the metal to cutting. But still, its total amount should not exceed 0.1%.
Oxygen is the most undesirable element in the composition of steel. The introduction of 0.001% oxygen can reduce the strength of the metal by 50%. Interferes with the processing of the alloy with a cutting tool.
Nitrogen. After it enters the metal, it forms iron nitrides - a very brittle compound, which reduces both the strength and technological properties of the alloy.

Features of low carbon steels

Low carbon steel is extremely ductile compared to other steels. Their relative specific compressive strength is 23-35%, depending on the percentage of carbon in the composition. The more it is, the lower the plasticity.

All grades of low-carbon steels have the first category of weldability.

The welding process does not require complex preparatory operations: surface heating, degreasing, etc. The weld is dense, when working in compression, the strength is comparable to solid metal. Reduced carbon steel lends itself to all types of welding: from conventional electric arc to vacuum in inert gas.

Low carbon steel does not have high strength characteristics. The tensile strength for it ranges from 320-450 MPa. The same can be said about hardness. Without additional hardening, the hardness of steel is 22-23 units on the Rockwell scale.

Low-carbon grades cannot be hardened due to the low carbon content in the composition. Among the few options for improving the steels of their mechanical properties release cementation. This is a type of chemical-thermal hardening, in which the surface of the metal is forcibly saturated with carbon, which makes the metal harder and more wear-resistant. In addition, as a mechanical hardening, they have proven themselves well different kind riveting, rolling rollers and so on.

Classification and brands

There are several main criteria by which carbon grades are classified. One of the most important among them is the conditions for carrying out deoxidation. The following low-carbon steels are distinguished:

Calm. It includes a minimum content of iron oxide in the composition, which makes the smelting process "calm" - without the rapid release of carbon dioxide from the metal mirror. This became possible due to the introduction of deoxidizers: aluminum, manganese and silicon. All outgoing gases accumulate in a shrinkage cavity, which is subsequently cut off, which results in a dense and uniform metal.
Boiling. Deoxidized with one manganese. They have an increased amount of iron oxide in the composition. The melting process is accompanied by the release of carbon dioxide, which gives the impression that the metal is boiling. These steels are less strong and less homogeneous in chemical composition, but they are cheap and have a low percentage of waste in production.
Semi-calm. In addition to manganese, aluminum is additionally used to remove oxygen. In terms of characteristics, this carbon steel is somewhere between boiling and calm alloys.

In addition to the degree of deoxidation, low-carbon grades are also classified by the presence of non-metallic inclusions in their composition. Based on this, they differ in:

Ordinary quality;
Quality engineering.

Let's consider each item in more detail.

Standard quality steel. They are not subject to strict requirements both for the choice of charge, and for melting and pouring. Phosphorus in them is allowed no more than 0.08%, and sulfur no more than 0.06%. Such an alloy is poured into large-sized ingots, so they are characterized by the appearance of zonal segregation.

Steel of ordinary quality is used for the production of various types of hot-rolled metal products: bars GOST 4290-90, channels GOST 8240-97, beams GOST 8239-95, corners GOST 8509-95 and others. This rolled product serves as a material for the production of various types of bolted, riveted and welded metal structures. In the machine tool industry, low-responsibility parts are produced from it that do not require heat treatment: axles, rollers, clamps, etc.

Based on the guarantee of these properties, ordinary quality steel can be:

Group "A". Delivery takes place according to mechanical characteristics, the chemical composition is not standardized. It is marked with "St" and a number from 0 to 6. (St.6, Art.5, etc.). As the number increases, the strength of the selected alloy also increases.
Group "B". Such metals come with a normalized chemical composition. The marking additionally prescribes the method of obtaining the alloy.
Group "B". Here, strength characteristics and chemical composition are simultaneously regulated in steels. The marking additionally indicates the letter B.

Quality engineering steels produced under more stringent smelting conditions. They have fewer harmful formations in the chemical composition: sulfur up to 0.04%, phosphorus up to 0.04%. They are marked with the inscription "steel" and a number indicating the amount of carbides in hundredths of a percent.

Steel 08 and 10 are used in critical mechanical engineering units. Bushings, coils, gaskets, etc. are produced from them. Before use, all parts must be carburized or any other chemical-thermal hardening.

Steels 15, 20, 25 are used for assemblies that work for wear and do not experience increased mechanical loads: levers, gears, valve lifters, etc.

How to get

The following low-carbon steels are distinguished depending on the smelting method:

Converter furnaces. The metal melts due to the chemical heat of exothermic reactions. Excess carbon is removed by blowing oxygen through a metal mirror. The advantage of this method is high productivity. The downside is the increased concentration of nitrogen at the outlet.
Open-hearth furnaces. Liquid fuel is burned in the working chamber. The required melting temperature is achieved due to the heat of the exhaust gases. With this method, the alloy is obtained more deoxidized and with a lower content of non-metallic impurities.