What is carbon and alloy steel

Grades and types of tool steel: description of carbon, alloy and high-speed

Tool steel is a material that consists of more than 0.7% carbon. Its key characteristics are hardness and strength, their maximum performance is achieved during heat treatment of steel. It is mainly used in the manufacture of various instruments.

This is the name given to steel containing more than 0.7% carbon. Its main characteristics are strength and hardness, which reach maximum values ​​after heat treatment. The main use of this steel material is in the manufacture of tools.

Advantages and range

Tool steel is one of the most popular materials on the market. The alloy has high hardness and low cost. However, the material also has a drawback - its low wear resistance, so it is not used for the production of machine parts and equipment that are subject to constant loads.

The range of this material is as follows:

• hot rolled squares and circles;
• forged strips, circles and squares.

Main types

This type of material is divided into the following three main categories:

• tool carbon steels;
• alloyed tool steels;
• high-speed.

All of them are produced in accordance with established GOST.

Carbon types of material lose their strength when heated; accordingly, they are used for the production of tools that operate at low speeds or under simple cutting conditions, when the heating temperature is no more than 200 degrees.

They are mainly used for the production of:

• files;
• drill;
• scans;
• taps and more.

Since carbon tool steel has low weldability, it is not used in the manufacture of welded structures.

Depending on the percentage of carbon, manganese, silicon, sulfur and other elements in the material, it is divided into the following grades:

• U7;
• U8;
• U8G;
• U10 and others.

Alloyed materials and their markings

Alloyed materials additionally contain the following elements:

• nickel;
• copper;
• manganese, etc.

All of them improve the characteristics of the material. Alloying elements must be indicated when marking using special symbols and letters. All this allows you to see in advance what a given tool steel consists of. Material brands can also include not only letters, but also numbers. The numbers indicate how much of a particular element is contained in steel as a percentage. If a number is not given when marking, then the amount of the element is about 1 percent.

When marking alloy steel, the first place is taken by the amount of carbon, which is equal to tenths of a percent. For example, grade 6ХС contains carbon in the amount of 0.6%, as well as one percent each of silicon and chromium.

Tool alloy steels are mainly used for the production of stamping or cutting tools, these include:

• dies;
• taps;
• sweeps;
• drill;
• cutters and more.

Like carbon steels, alloy materials are also unsuitable for the production of welded structures.

High speed steels

The marking of high-speed materials consists of the letter “P”, a number indicating the mass fraction of tungsten and the letters of the elements present in the material. This can be cobalt, molybdenum and others. Next come the digital values ​​of their mass fractions. If the marking includes the letters “Ш”, then this means “electroslag remelting”.

The proportion of chromium in high-speed steel is not indicated when marking, and there is also no indication of the mass fraction of molybdenum if it does not exceed one percent.

These types of materials are optimally suited for the production of cutting tools, which, due to friction, are heated to temperatures from 600 to 6500 degrees. At the same time, they will not deform and lose their hardness. This type of product lends itself well to welding using electric butt welding with steel grades such as 45 and 40X.

All brands for production are divided into the following groups:

• heat-resistant and tough - usually these are hypereutectoid and hypoeutectoid steels, including chromium, molybdenum and tungsten. Carbon in steels should correspond to low and medium values;
• highly hard and viscous, as well as non-heat-resistant - the alloys contain a minimum of alloyed elements, as well as an average amount of carbohydrate, characterized by low hardenability;
• High-hardness and heat-resistant, as well as wear-resistant - these are high-speed alloy steels with a high content of alloyed elements, alloys with a ledeburite structure, which contain more than 3 percent carbon;
• wear-resistant, highly hard with average heat resistance - the materials have a hypereutectoid and ledeburite structure, their composition contains approximately 2-3 percent carbon and 5-12 percent chromium;
• high-quality and high-quality tool steel - differ from each other in the percentage of sulfur and phosphorus present in them;
• highly hard and non-heat resistant - these tool steels with a hypereutectoid structure do not include alloy elements at all, or they are present in minimal quantities. Their level of hardness is ensured by the large amount of carbon in the composition.

The hardness level is a very important parameter for the material in question. Typically, high-hardness steels are not used for the production of tools that are subject to heavy impact loads during operation. This is due to the fact that these alloys have low viscosity and high fragility, which is why the tool made from them can break.

In terms of hardness, these steel materials come with a high level of viscosity, where the carbon content is 0.4-0.7%, or with high wear resistance and hardness, where the amount of carbohydrate is 0.7-1.5%.

Steels also differ in the degree of their hardenability . According to this criterion they are divided into:

• products with increased hardenability, where the hardening diameter is from 80 to 100 mm;
• high - diameter from 50 to 80 mm;
• low - from 10 to 25 mm, respectively.

Areas of use

This material has a fairly wide range of applications in industry. They are used in the manufacture of:

• cutting tools;
• measuring devices;
• casting molds operating under pressure;
• working parts of dies that operate on the principle of hot and cold deformation;
• high-precision products.

Requirements for these materials depend on how exactly they will be used. But there are general requirements for them, regardless of brand:

• high level of hardness;
• high level of strength;
• wear resistance;
• good viscosity, which is especially important in the manufacture of parts that will be subject to shock during use;
• low level of sensitivity to overheating, adhesion and welding processes to parts that are subject to processing;
• good level of processing through metal cutting;
• resistance to cracks;
• susceptibility to calcination;
• hot plasticity;
• possibility of grinding;
• the ability to resist decarbonization.

Naturally, these are not all the requirements. Thus, grades that are intended for use in cold deformation conditions must additionally have a smooth working surface, retain their shape and size, and have a yield and elasticity limit. And those materials that must be used under conditions of hot deformation must have high thermal conductivity, prevent tempering and be resistant to temperature fluctuations.

So, you have examined the features of tool steel, found out what types and categories it is divided into and for what purposes this or that brand is used. More information about them can be read in other articles devoted to this material.

Source: https://tokar.guru/metally/stal/instrumentalnye-stali-uglerodistye-i-legirovannye-marki.html

Carbon and alloy steel difference

Alloy steel is steel containing special alloying additives that can significantly change a number of its mechanical and physical properties. In this article we will understand what the classification of alloy steels is, and also consider their markings.

Alloy steel round bars

Classification of alloy steels

Based on the carbon content of steel, it is divided into:

Depending on the total amount of alloying elements that alloy steel contains, it can belong to one of three categories:

1. low alloy (no more than 2.5%);
2. medium alloyed (no more than 10%);
3. highly alloyed (from 10% to 50%).

The properties of alloy steels are determined by their internal structure. Therefore, the classification of alloy steels implies division into the following classes:

1. hypoeutectoid - the composition contains excess ferrite;
2. eutectoid - steel has a pearlite structure;
3. hypereutectoid - their structure contains secondary carbides;
4. ledeburite - the structure contains primary carbides.

According to their practical application, alloyed structural steels can be: structural (divided into machine-building or construction), tool, and also steels with special properties.

Purpose of structural alloy steels:

• Mechanical engineering - used for the production of parts for various mechanisms, body structures, and the like. They differ in that in the vast majority of cases they undergo heat treatment.
• Construction - most often used in the manufacture of welded metal structures and are subjected to heat treatment in rare cases.

The classification of engineering alloy steels is as follows.

• Heat-resistant steels are actively used for the production of parts intended for work in the energy sector (for example, components for steam turbines), and they are also used to make especially important fasteners. Chromium, molybdenum, and vanadium are used as alloying additives. Heat-resistant steels refer to medium-carbon, medium-alloy, pearlitic steels.
• Improved steels (from the categories of medium-carbon, low- and medium-alloyed) steels, in the production of which hardening is used, are used for the manufacture of heavily loaded parts that experience variable loads. They differ in sensitivity to stress concentration in the workpiece.
• Case-hardened steels (from the categories of low-carbon, low- and medium-alloyed) steels, as the name suggests, are subject to carburization followed by hardening. They are used for the manufacture of all kinds of gears, shafts and other parts similar in purpose.

Dependence of the thickness of the cemented layer on temperature and processing time

The classification of construction alloy steels implies their division into the following types:

• Bulk - low-alloy steel in the form of pipes, shaped and sheet products.
• Bridge construction - for road and railway bridges.
• Shipbuilding cold-resistant, normal and high-strength - well resistant to brittle fracture.
• Shipbuilding cold-resistant high strength - for welded structures that will operate in low temperature conditions.
• For hot water and steam - operating temperatures up to 600 degrees are allowed.
• Low-cut, high-strength - used in aviation, sensitive to stress concentration.
• Increased strength using carbonitrite hardening, creating a fine-grained steel structure.
• High strength using carbonitrite hardening.
• Strengthened by rolling at a temperature of 700-850 degrees.

Application of tool alloy steels

Tool alloy steel is widely used in the production of various tools. But in addition to its obvious superiority over carbon steel in terms of hardness and strength, alloy steel also has a weak side - higher fragility.

Therefore, such steels are not always suitable for tools that are actively exposed to shock loads.

Nevertheless, in the production of a huge range of cutting, impact-stamping, measuring and other tools, alloy tool steels remain indispensable.

Separately, we can note high-speed steel, the distinctive features of which are extremely high hardness and red resistance up to a temperature of 600 degrees. Such steel is able to withstand heat at high cutting speeds, which allows you to increase the speed of metalworking equipment and extend its service life.

A separate category includes alloyed structural steels, endowed with special properties: stainless, with improved electrical and magnetic characteristics. Depending on what elements, as well as in what quantities, are predominantly contained in them, they can be chromium, nickel, chromium-nickel-molybdenum. They are also divided into three-, four- and more-component ones according to the number of alloying additives they contain.

Alloying elements and their influence on the properties of steels

The marking of alloy steels indicates what additives it contains, as well as their quantitative value. But it is also important to know exactly what effect each of these elements has on the properties of the metal separately.

Chromium

The addition of chromium increases corrosion resistance, increases strength and hardness, and is the main component in the creation of stainless steel.

Nickel

The addition of nickel increases the ductility, toughness and corrosion resistance of steel.

Titanium

Titanium reduces the graininess of the internal structure, increasing strength and density, improving machinability and corrosion resistance.

Vanadium

The presence of vanadium reduces the graininess of the internal structure, which increases fluidity and tensile strength.

Molybdenum

The addition of molybdenum makes it possible to improve hardenability, increase corrosion resistance and reduce brittleness.

Tungsten

Tungsten increases hardness, prevents grains from expanding when heated, and reduces brittleness when tempered.

Silicon

At contents of up to 1-15%, silicon increases strength while maintaining toughness. As the percentage of silicon increases, magnetic permeability and electrical resistance increase. This element also increases elasticity, corrosion resistance and oxidation resistance, but also increases fragility.

Cobalt

The introduction of cobalt increases impact resistance and heat resistance.

Aluminum

The addition of aluminum improves scale resistance.

Table of purpose of some types of steel

Separately, it is worth mentioning impurities and their effect on the properties of steels. Any steel always contains technological impurities, since it is extremely difficult to completely remove them from the steel composition. These types of impurities include carbon, sulfur, manganese, silicon, phosphorus, nitrogen and oxygen.

Carbon

It has a very significant effect on the properties of steel. If it is contained up to 1.2%, then carbon helps to increase the hardness, strength, and yield strength of the metal.

Exceeding the specified value contributes to the fact that not only strength, but also ductility begins to deteriorate significantly.

Manganese

If the amount of manganese does not exceed 0.8%, then it is considered a technological impurity. It is designed to increase the degree of deoxidation and also counter the negative effects of sulfur on steel.

Sulfur

When the sulfur content exceeds 0.65%, the mechanical properties of steel are significantly reduced, we are talking about a decrease in the level of ductility, corrosion resistance, and impact strength. Also, high sulfur content negatively affects the weldability of steel.

Phosphorus

Even a slight excess of phosphorus content above the required level is fraught with an increase in brittleness and fluidity, as well as a decrease in the toughness and ductility of steel.

Nitrogen and oxygen

When certain quantitative values ​​in the steel composition are exceeded, inclusions of these gases increase brittleness and also contribute to a decrease in its endurance and toughness.

Hydrogen

Too much hydrogen content in steel leads to increased brittleness.

Marking of alloy steels

The category of alloyed steels includes a wide variety of steels, which necessitated the need to systematize their alphanumeric designations. The requirements for their marking are specified by GOST 4543-71, according to which alloys endowed with special properties are indicated by markings with a letter in the first position. By this letter it is possible to determine that the steel, by its properties, belongs to a certain group.

An example of deciphering alloy steel markings

So, if the marking of alloy steels begins with the letters “F”, “X” or “E” - we have an alloy of the stainless, chromium or magnetic group. Steel, which belongs to the stainless chromium-nickel group, is designated by the letter “I” in its marking. Alloys belonging to the category of ball bearing and high-speed tool alloys are designated by the letters “Ш” and “Р”.

  The best steel for an ax

Steels classified as alloyed may belong to the category of high-quality, as well as especially high-quality. In such cases, the letter “A” or “W” is placed at the end of their mark, respectively.

Steels of ordinary quality do not have such designations in their markings. Alloys that are produced by the rolling method also have a special designation.

In this case, the marking contains the letter “N” (hard-worked rolled steel) or “TO” (heat-treated rolled steel).

The exact chemical composition of any alloy steel can be found in regulatory documents and reference literature, but the ability to understand its markings also allows one to obtain such information. The first figure allows you to understand how much carbon (in hundredths of a percent) alloy steel contains. After this number, the brand lists the letter designations of alloying elements that are additionally contained.

Designation of alloying elements in steel markings

After each such letter the quantitative content of the specified element is indicated. This content is expressed in whole fractions. There may not be any number after the letter indicating the element. This means that its content in steel does not exceed 1.5%.

State standard 4543-71 regulates the designation of alloying additives included in alloy steel: A - Nitrogen, B - Niobium, C - Tungsten, G - Manganese, D - Copper, K - Cobalt, M - Molybdenum, N - Nickel, P - Phosphorus, P - Boron, S - Silicon, T - Titanium, C - Zirconium, F - Vanadium, X - Chrome, Yu - Aluminum.

Use of alloy steels

Today it is difficult to find an area of ​​life and activity in which alloy steel would not be used.

Almost any tool is made from tool and structural steels: cutters, milling cutters, dies, measuring devices, gears, springs, pendants, braces and much more.

Stainless alloy steels are actively used in everyday life; they are used to make dishes, cases and other elements of many types of household appliances.

Due to their high cost, alloy steels are used only for the production of the most critical structures and parts, where products made from other metals simply cannot perform the tasks assigned to them.

Source: https://varimtutru.com/uglerodistaya-i-legirovannaya-stal-raznitsa/

Carbon steel - properties, grades, classification and application of steels

Any specialist who deals with metal is familiar with the concept of “steel grade”. Deciphering the markings of steel alloys makes it possible to get an idea of ​​their chemical composition and physical characteristics. Understanding this marking, despite its apparent complexity, is quite simple - it is only important to know on what principle it is compiled.

Rarely does production operate without steel, so understanding its grades is extremely important

The alloy is designated by letters and numbers, which can be used to accurately determine which chemical elements it contains and in what quantity. Knowing this, as well as how each of these elements can affect the finished alloy, it is possible to determine with a high degree of probability exactly what technical characteristics are characteristic of a particular grade of steel.

What is steel and its difference from cast iron

Iron-carbon alloy is the well-known steel. Typically, the proportion of carbon in the alloy varies from 0.1 to 2.14%. Increasing carbon concentration makes steel brittle. In addition to the main components, the alloy also contains small amounts of magnesium, manganese and silicon, as well as harmful sulfur and phosphorus impurities. The basic properties of steel and cast iron are very similar. Despite this, there are significant differences between them:

• steel is a stronger and harder material than cast iron;
• cast iron, despite the deceptive massiveness of cast iron products, is a lighter material;
• Since steel contains a negligible percentage of carbon, it is easier to process. For cast iron, casting is preferable;
• products made of cast iron retain heat better due to the fact that its thermal conductivity is significantly lower than that of steel;
• hardening of the metal, which increases the strength of the material, is impossible with cast iron.

Advantages and disadvantages of steel alloys

Since there are a huge number of steel brands, and even more products made from it, it is pointless to talk about the pros and cons. Moreover, the properties of the metal largely depend on manufacturing and processing technologies.

As a result, we can only highlight a few general advantageous features of steel, such as:

• strength and hardness;
• viscosity and elasticity, that is, the ability not to deform and withstand shock, static and dynamic loads;
• accessibility for different processing methods;
• durability and increased wear resistance compared to other metals;
• availability of raw materials, cost-effectiveness of production technologies.

Unfortunately, there are also some disadvantages:

• instability to corrosion, including a high level of electrochemical corrosion;
• steel is a heavy metal;
• The manufacture of steel products is carried out in several stages; violation of technology at any of them leads to a decrease in quality.

Material cost

The cost of the material is no less varied than the number of brands. Standard steel on the London Metal Exchange in December 2020 costs $325 per ton. Stainless steel costs are noticeably higher, with cold-rolled 304 grade stainless steel priced between $1,890 and $1,925 per ton in December.

Steel is the most popular and most widespread metal alloy in the world. When talking about the role of iron in the national economy, we mean specifically various steel alloys.

To see how steel melts, watch the video below:

Types and classifications of steel alloys

Today it is difficult to determine the number of steel alloys produced and used. It is also not easy to classify them, since their properties depend on many parameters, such as composition, nature and amount of additives, manufacturing and processing methods, purpose and many others.

Based on quality, it is customary to distinguish between ordinary, high-quality, high-quality and especially high-quality steels. The proportion of harmful impurities is the main criterion for determining the quality of the alloy. Ordinary steels are characterized by higher values ​​of the proportion of impurities than especially high-quality alloys.

Chemical composition of steel . The production of iron alloys is based on its ability to form different structural phases at different temperatures, the so-called polymorphism. Thanks to this ability, impurities dissolved in iron form alloys of various compositions.

It is customary to divide steel alloys into carbon and alloy .

Steel, by definition, is an alloy of iron and carbon, the concentration of which determines its properties: hardness, strength, ductility, toughness. Carbon steel contains practically no additional additives.

Basic impurities - manganese, magnesium, and silicon are contained in minimal quantities and do not impair its properties and qualities. Silicon and manganese have a deoxidizing effect on the alloy, increasing elasticity, wear resistance, and heat resistance. But, in case of increasing the proportion, they are alloying elements. Steels with a high manganese content lose their magnetic properties.

Sulfur and phosphorus impurities are much more harmful for both types of steel. Sulfur, when combined with iron, increases brittleness when processed at high temperatures (rolling, forging), increases fatigue, and reduces corrosion resistance.

Phosphorus, especially with a large proportion of carbon in the alloy, increases its brittleness under normal temperature conditions. In addition, there is a whole group of hidden harmful impurities that cannot be removed during smelting. These non-metallic inclusions in the form of nitrogen, hydrogen and oxygen make the metal more friable during hot processing.

Types of Carbon Steel

Carbon steels are divided into types, which are characterized by the proportion of carbon content:

Source: https://instanko.ru/drugoe/stal-eto.html

Difference between alloy steel and carbon steel

The steel industry is one of the largest industries in the world. Steel is produced primarily by mixing iron with other metallic or non-metallic elements. The purpose of steel production is to obtain various properties by mixing iron with other elements.

Alloy steel and carbon steel are two types of steel that differ from each other in their composition.

The main difference between alloy steel and carbon steel is that alloy steel has large amounts of elements other than iron and carbon while carbon steel has trace amounts of elements other than iron and carbon.

Key areas covered

1. What is alloy steel - Definition, properties, uses

2. What is carbon steel

— Definition, properties, use

3. What is the difference between alloy steel and carbon steel

— Comparison of the main differences

Key terms: alloy steel, carbon, carbon steel, iron, steel

What is alloy steel

Alloy steel is a metal alloy of iron, carbon and a large number of other elements. Other elements present in it typically include manganese, silicon, nickel, titanium, copper and chromium. These elements are called alloy elements because these elements are mixed together to form an alloy. The purpose of adding these elements is to improve the properties of the steel. Alloy steel can be divided into two categories as follows.

• Low alloy steel
• High alloy steel

Low alloy steels contain small amounts of alloying elements, while high alloy steels contain large amounts of alloying elements. Alloying elements are usually added to improve the hardness and durability of steel. Alloy steel is also resistant to corrosion due to the presence of significant amounts of other elements such as chromium.

For example, stainless steel is an alloy steel. It contains about 10% chromium along with iron and carbon in the mixture of elements. Due to its anti-corrosion resistance, stainless steel is used to make kitchen items.

Figure 1: Stainless steel (alloy steel) check valve.  

What is carbon steel

Carbon steel is made up of iron and carbon. Alloying elements are present in trace amounts. Some of these elements are silicon, manganese, sulfur and phosphorus. Carbon steel is also divided into two groups as shown below.

• High carbon steel
• Low carbon steel

Due to the high amount of carbon present in carbon steel, it exhibits properties such as hardness, less ductility, reduced weldability and low melting point.

Mild steel refers to low carbon steel with a carbon content of 0.05 to 0.25%. Due to its high iron content, it is corrosive in humid environments. High carbon steels contain between 0.6% and 1.0% carbon. These high carbon steels are very strong.

Therefore, carbon steels are used as building materials.

Figure 2: Carbon steel used as a building material

Definition

Alloy Steel: Alloy steel is a type of steel with a high percentage of elements other than iron and carbon.

Carbon Steel: Carbon steel is a type of steel that is high in carbon and low in other elements.

Corrosion resistance

Alloy Steel: Alloy steels are resistant to corrosion.

Carbon Steel: Carbon steels are less resistant to corrosion.

Strength

Alloy Steel: The strength of alloy steel is low compared to carbon steel.

Carbon Steel: Carbon steel has high strength.

weldability

Alloy steel: The weldability of alloy steel is high.

Carbon Steel: The weldability of carbon steel is low.

Melting temperature

Alloy Steel: Alloy steels have high melting points.

Carbon Steel: Carbon steels have low melting points.

stringiness

Alloy steel: The ductility of alloy steel is high.

Carbon Steel: The ductility of carbon steel is low.

Conclusion

The composition of the elements in steel differs from one type of steel to another. Therefore, steels are classified mainly according to their composition. Alloy steel and carbon steel are such two types of steel. The main difference between alloy steel and carbon steel is that alloy steel has large amounts of elements other than iron and carbon, whereas carbon steel has trace amounts of elements other than iron and carbon.

Recommendations:

1. “Information on carbon steels and alloy steels.” Information on Carbon Steels and Alloy Steels | Engineering360. N.p., n.d. Web.

Source: https://ru.strephonsays.com/difference-between-alloy-steel-and-carbon-steel

Carbon steel

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Carbon steel Carbon steel ( 1 vote, average: 4 out of 5)

Carbon steel is a tool steel containing 0.04-2% carbon and always present impurities, and does not contain alloying alloy elements. Carbon steel, depending on the percentage of carbon, is divided into three main types:

• low carbon;
• medium carbon;
• high carbon.

This material requires heat treatment, after which it becomes hard and durable enough to withstand sufficient loads in critical components. Spav is used in tool production. Carbon steel is classified as:

• high-quality, contains up to 0.035% phosphorus and sulfur;
• high quality, contains up to 0.025% phosphorus and sulfur.

Carbon steel grade

of carbon steel grades . According to GOST 1435-99, the metallurgical industry produces the following grades of carbon tool steel:

• U7;
• U7A;
• U8;
• U8A;
• U9A;
• U10;
• U11;
• UNA;
• U12;
• U12A;
• U13;
• U13A.

The letter U draws attention to the fact that the steel is carbon. The designation of the letter A, at the end of the brand, means a group of high-quality steel with a purer presence of sulfur and phosphorus. The numbers in the designation indicate the percentage of carbon in the alloy, the numerical expression of which is multiplied by 10 for convenience. The absence of the letter A means high-quality steel. The number indicates the carbon content, average, G- indicates the high presence of manganese.

Carbon steel grades have low cost and high hardness and this distinguishes them from other tool steels. The wear resistance of these brands and heat resistance are low. Carbon steel grades U7, U7A are successfully used for woodworking tools - axes, chisels, chisels, as well as metal tools - chisels, forging dies, metalworking tools, hammers, sledgehammers, screwdrivers, wire cutters, etc.

Grades U8, U8A, U8G, U8GA are used for the manufacture of tools that are very resistant to heating during operation and can withstand rotational loads - wood cutters, countersinks, longitudinal saws, circular saws, knurling rollers, etc. Carbon steel grades U10, U10A are used for making needle wire, also a tool that does not cause heating of the cutting edge.

U13, U13A are used for tools where increased wear resistance is required, razor blades, surgical instruments, tools for engraving metal and stone.

Properties of carbon steel

The properties of carbon steel are greatly improved when it is heat treated. After this process, the alloy acquires high hardness, strength, the ability to respond to heavy loads, and withstand high temperatures during operation of the cutting edge.

The properties of carbon steel allow it to be one of the most popular types of steel. The characteristics and properties of the material are regulated during smelting, observing the necessary standards for the percentage of alloy elements.

The properties of carbon steel allow it to be successfully welded and processed by cutting; alloying elements introduced into it change the properties, mechanical abilities increase, and cold brittleness decreases.

Types of Carbon Steel

Types of carbon steel are divided into:

• A - supplied according to its mechanical properties, which can be changed;
• B- by its chemical properties, while the mechanical properties change, and the level is determined by the chemical composition;
• B- are supplied according to the chemical content and their mechanical properties for parts.

Types of carbon steel according to the type of processing are distinguished:

• hot rolled;
• forged;
• calibrated;
• round with special surface finishing.

According to the degree of deoxidation:

• semi-calm;
• calm;
• boiling.

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Source: https://metallsmaster.ru/uglerodistaya-stal/

Carbon or alloy steel: comparison and which is better

There are about 700 grades of steel , each of which has specific qualities, but new ones are developed every year. The variety of properties of alloys is determined by: the presence of alloying elements, the amount of carbon (C), and the percentage of harmful impurities. Depending on the content of the latter, primarily sulfur and phosphorus, alloys are divided into high-quality and ordinary quality.

According to the degree of oxygen content, steels are classified as: boiling (kp), semi-calm (ps), calm (sp). The former are fragile, susceptible to corrosion, and have poor weldability. Semi-calm has intermediate characteristics between the SP and KP brands. Alloys marked cn are more homogeneous, weld well, and have increased resistance to impact loads. The most significant substance that changes the characteristics of steel is carbon.

Carbon steels

Carbon, while increasing hardness, also makes the alloy more brittle. The percentage content of the element is reflected in the marking - you can use it to determine what material is in front of you. Please note that the first two digits reflect the presence of hundredths of a percent of the element, one – tenths.

If the carbon content is up to 0.25% , then the steel is low-carbon, and therefore inexpensive, easy to weld. If from 0.3 to 0.55% , then the alloy is medium-carbon; these are actively used in mechanical engineering.

The amount of an element in the range of 0.6-2% shows that the material is high-carbon, therefore its weldability and fluidity are low, but its hardness is high.

The structure of low-carbon alloys provides plasticity, but relatively low strength of the material. An increase in carbon content leads to a loss of ductility, but significantly increases strength. Thus, high-carbon steel is a very hard, durable alloy, for which they try to avoid the use of welding whenever possible. Wire, bearings, springs, and stamped parts are produced from it.

Alloy steels

By adding certain substances to the composition of steel alloys, the necessary properties can be achieved; this operation is called alloying. For example:

1. Chromium - increases hardness, strength, corrosion resistance, but impairs ductility.
2. Nickel - increases ductility and corrosion resistance, but can reduce hardness; it is often used together with manganese.
3. Tungsten , molybdenum - impart hardness, enhance heat resistance, reduce brittleness during tempering.
4. Manganese - optimizes impact resistance and hardness without compromising ductility.
5. Aluminum – improves heat resistance, as well as scale resistance and corrosion resistance.
6. Silicon – makes the metal strong while maintaining its toughness. Improves electrical resistance, elasticity, acid resistance. Compared to other alloying elements, it is less expensive.

Alloy steels, having unique qualities, are used for the production of products where they cannot be replaced by other materials. They are classified according to purpose, structure, percentage of alloying elements, and chemical composition.

Areas of use

Any steel consists of iron, carbon, impurities - but each grade is designed to solve certain, sometimes specific problems. The characteristics of the materials are specialized, and the choice of brand should be approached responsibly. It is worth considering that:

1. The inclusion of alloying additives expands the range of possible uses of the metal, but significantly increases the price. Therefore, when choosing a brand, they are guided not only by improving the characteristics of the metal, but also by economic feasibility, the cost of production, and the scarcity of alloying elements.
2. The weldability of low-carbon steels is high, but for alloy and high-carbon steels this is a labor-intensive operation that requires the qualification of the performer.
3. Tool carbon steel has a serious disadvantage - when heated, it loses hardness and cutting ability . Therefore, if the cutting tool heats up, then alloy metal is preferable. Many alloy steels are exceptional in their properties ; there are steel grades: magnetic, hard magnetic, with increased electrical resistance, heat-resistant, stainless, and scale-resistant. They are indispensable in the aviation, chemical, and military industries.

The most commonly used steel is low-carbon steel of ordinary quality, marked Art. It is needed in construction, mechanical engineering, and production. From it they produce:

• Fasteners (St1)
• Sheet iron (St3, St2)
• Rails, cams (St6)
• Shafts, axles, wedges (St5)
• Gears, flanges (St3)
• Wire (St2)

In general, carbon steels are inferior in most respects to alloy steels, but they are quite reliable, high-quality, cheap, and therefore in demand. When choosing a brand of material, it is worth studying the reference literature, the advantages and disadvantages of a particular brand, taking into account many other parameters, including the operating conditions required: rigidity, malleability, ductility, price, availability. It is impossible to choose one steel and say that it is ideal - each of them is good for its own case.

Source: https://vchemraznica.ru/uglerodistaya-ili-legirovannaya-stal-sravnenie-i-chto-luchshe/

Carbon steels: features, classification, processing

Carbon steel is a metallurgical composition with a low content of additives and a high iron content - up to 99 ½%. This material is in high demand in various industries, which explains its high share in production - up to 80%.

Today, about 2 thousand brands have been developed. The structure of a material depends on its carbon content. By changing the percentage you can influence characteristics such as hardness, fluidity, ductility and density.

The carbon content of the material is critical at 0.8%.

Regarding this indicator, the US is distinguished:

• if C is less than 0.8%, ferrite and pearlite are present in the structure of the material;
• at a C (carbon) content of 0.8%, the material is characterized by a pearlite structure;
• when the C content is more than 0.8%, cementite appears in the structure.

The general trend with increasing C content is expressed in an increase in strength, impact strength and cold brittleness threshold, but the ductility of rolled products decreases.

Classification of carbon steels

In addition to classification by structural parameters, they are usually distinguished by production technology:

• electric control systems;
• open hearth;
• oxygen converter.

The material is divided according to the level of deoxidation:

• calm;
• boiling;
• semi-calm.

In terms of quality, in accordance with the presence and volume of harmful impurities, the iron alloy is:

• normal quality;
• quality steel.

According to the scope of use of the control system there are:

• ordinary;
• instrumental;
• structural.

Based on the presence and volume of C in the carbon iron alloy, the material is classified:

• high-carbon steel grades with a C content of more than 0.65%;
• medium carbon - from 0.25 to 0.6%;
• low-carbon steel grades with a C content of up to 0.25%.

The higher the carbon indicators, the harder and stronger the material, but also the higher its fragility. The marking of a material is directly related to its purpose:

• Ordinary quality is designated by the conventional letter designation Art. This is followed by numbers from 1 to 7, which show the C (carbon) content, a multiple of 10. The production of iron alloys of this group is regulated by GOST 380-85. Additionally, these materials are usually distinguished by supply group: A, B and C. This designation is indicated before the brand (group A is not indicated). For A - the mechanical properties are stable, for B the mechanical composition is stable, for C the properties and composition are stable.
• Structural control systems are regulated by GOST 380-88, marking is carried out with numbers: from 08 to 85. These numbers inform about the C (carbon) content in the material in hundredths of a percent. If an iron alloy is characterized by an increased manganese content, G is indicated at the end of the marking.
• Instrumental control systems are regulated by GOST 1435-54 and 5952-51. This iron alloy is of high quality and is marked with the letter U. This is followed by numbers that show the volume of carbon in tenths of a percent. There is a subgroup of the highest quality, in this case the designation ends with the letter A. They are characterized by a high carbon content.

Read also: Main grades of heat-resistant steels and alloys, their application

It is customary to indicate the degree of deoxidation in the brand designation: ps or ks.

The percentage of C in the composition of tool steel is determined by its use. U7 - for the production of forging hammers, dies and chisels, U8 is used for the production of tools for working with stone and metal, U9 is optimal for the production of stamps and punches. Subsequent modifications are used to produce blades of hacksaws, drills, dies, and cutters.

The difference between carbon steels and alloy steels

US grades distinguish between technological processes and the use of various additives. So what is the difference between carbon steels and alloy steels if elements are also added to these iron alloys that change the mechanical, operational and technological parameters:

• Carbon iron alloys contain iron, carbon and normal impurities, which can be beneficial or harmful. The first include manganese and silicon. Harmful impurities are sulfur and phosphorus.
• The material does not contain alloying additives that change properties, such as molybdenum, titanium, tungsten and others.
• CS are not intended for special use; it is a general industrial material.
• Compared to alloyed materials, carbon alloys have lower technological and operational parameters, including hardness and heat resistance.

Read also: Grades of medical steel: GOST USSR and its classification

Scope of application of carbon steels

The scope of application of the control system is determined by the type. Thus, low-carbon steel is used for cold deformation and hot forging; its grades are characterized by high ductility. Iron alloys with an average carbon content differ slightly in terms of fluidity and ductility, but its strength is already higher.

They are relevant for the production of structural elements and mechanisms that will be used under normal conditions. CWs with a high carbon content have high strength; various tools and measuring instruments are made from them. Standard quality control is used in the production of sheet material, channels, rods, beams and other products.

  Machine elements and metal structures are made from it.

Carbon steel processing

The main types of carbon processing are: annealing, hardening, normalization, aging and tempering.

• Carbon steels of ordinary quality. Group A alloy is supplied for products that are not processed. Group B - these are materials that are intended for stamping, forging, and sometimes heat treatment. Group B is alloys that can be processed by welding.
• High quality carbon steel. This material can be subjected to thermal processing, normalization, cold machining, upset, stamping and pressure processing. Features of the technological process depend on the specific brand.

One of the main advantages of this iron alloy is its low cost. It is this factor that determines the wide applicability of the material.

Source: http://solidiron.ru/steel/uglerodistye-stali-osobennosti-klassifikaciya-obrabotka-i-oblast-primeneniya.html

Compound

Depending on the amount of carbon, carbon and alloy steel are divided. The presence of carbon gives the material strength and hardness, and also reduces viscosity and ductility. Its content in the alloy is up to 2.14%, and the minimum amount of impurities due to the manufacturing process allows the bulk to consist of iron up to 99.5%.

High strength and hardness are what characterize carbon steel.

Impurities that are constantly included in the structure of carbon steel have a small content. Manganese and silicon do not exceed 1%, and sulfur and phosphorus are within 0.1%. An increase in the amount of impurities is characteristic of another type of steel, which is called alloyed.

The lack of technical ability to completely remove impurities from the finished alloy allows the following elements to be included in carbon steel:

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

The presence of these substances is determined by the steel melting method: converter, open-hearth or other. And carbon is added on purpose. If the amount of impurities is difficult to regulate, then adjusting the level of carbon in the composition of the future alloy affects the properties of the finished product. When the material is filled with carbon up to 2.4%, steel is classified as carbon.

Characteristic

The characteristics and structure of the metal are changed using heat treatment, through which the required surface hardness or other requirements for the use of the steel structure are achieved.

However, not all structural properties can be adjusted using thermal methods. Such structurally insensitive characteristics include rigidity, expressed by the elastic modulus or shear modulus.

This is taken into account when designing critical components and mechanisms in various fields of mechanical engineering.

In cases where the calculation of the strength of an assembly requires the use of small-sized parts that can withstand the required load, heat treatment is used. This effect on “raw” steel makes it possible to increase the rigidity of the material by 2-3 times. The metal that is subjected to this process is subject to requirements regarding the amount of carbon and other impurities. This steel is called high quality.

Marking

When designating carbon steels of ordinary quality, the letters St are used, which are accompanied by numbers characterizing the carbon content. One digit shows the quantity multiplied by 10, and two digits by 100. When guaranteeing the mechanical composition of the alloy, B is added before the designation, and compliance with the chemical constituents is B.

At the end of the marking, two letters indicate the degree of deoxidation: ps - semi-quiet, kp - boiling state of the alloys. For calm metals this indicator is not indicated. An increased amount of manganese in the structure of the product is designated by the letter G.

When designating high-quality carbon steels used in the manufacture of tools, the letter U is used, next to which a number is written confirming the percentage of carbon in a 10-fold amount, regardless of whether it is two-digit or single-digit. To highlight higher quality alloys, the letter A is added to the designation of tool steels.

Examples of designation of carbon steels: U8, U12A, St4kp, VSt3, St2G, BSt5ps.

Production

The metallurgical industry produces metal alloys. The specificity of the process for producing carbon steel is the processing of cast iron billets with the reduction of suspended matter such as sulfur and phosphorus, as well as carbon, to the required concentration. The differences in the oxidation technique by which carbon is removed allows us to distinguish different types of smelting.

Oxygen converter method

The basis of the technique was the Bessemer method, which involves blowing air through liquid cast iron. During this process, carbon is oxidized and removed from the alloy, after which the iron ingots gradually turn into steel.

The productivity of this technique is high, but sulfur and phosphorus remained in the metal. In addition, carbon steel is saturated with gases, including nitrogen.

This improves strength but reduces ductility, making the steel more prone to aging and high in non-metallic elements.

Given the low quality of steel produced by the Bessemer method, it was no longer used. It was replaced by the oxygen-converter method, the difference of which is the use of pure oxygen, instead of air, when purging liquid cast iron.

The use of certain technical conditions during purging significantly reduced the amount of nitrogen and other harmful impurities.

As a result, carbon steel produced by the oxygen-converter method is close in quality to alloys melted in open-hearth furnaces.

The technical and economic indicators of the converter method confirm the feasibility of such smelting and make it possible to replace outdated methods of steel production.

Open hearth method

A feature of the method for producing carbon steel is the burning of carbon from cast iron alloys not only with the help of air, but also by adding iron ores and rusty metal products. This process usually takes place inside furnaces, to which heated air and combustible gas are supplied.

The size of such melting baths is very large; they can hold up to 500 tons of molten metal. The temperature in such containers is maintained at 1700 ºC, and carbon burning occurs in several stages. First, due to excess oxygen in flammable gases, and when slag forms above the molten metal, through iron oxides. When they interact, slags of phosphates and silicates are formed, which are subsequently removed and the steel acquires the required quality properties.

Steel melting in open hearth furnaces takes about 7 hours. This allows you to adjust the desired composition of the alloy when adding different ores or scrap. Carbon steel has long been manufactured using this method. Such stoves, in our time, can be found in the countries of the former Soviet Union, as well as in India.

Electrothermal method

It is possible to produce high-quality steel with a minimum content of harmful impurities by melting it in vacuum furnaces of electric arc or induction furnaces. Thanks to the improved properties of electric steel, it is possible to produce heat-resistant and tool alloys. The process of converting raw materials into carbon steel occurs in a vacuum, due to which the quality of the resulting workpieces will be higher than the previously discussed methods.

The cost of such metal processing is more expensive, so this method is used when there is a technological need for a high-quality product. To reduce the cost of the technological process, a special ladle is used, which is heated inside a vacuum container.

Application

Carbon steel, due to its properties, has found wide application in various sectors of the national economy, especially in mechanical engineering.

The use of metal’s ability to resist loads and have high fatigue limits in design calculations makes it possible to manufacture from carbon steel such critical machine parts as: flywheels, gear drives, connecting rod housings, crankshafts, plunger pump pistons, and technological equipment for woodworking and light industry.

High-carbon steels with an increased amount of manganese are used for the manufacture of parts such as springs, leaf springs, torsion bars and similar components that require the elasticity of the alloy. Tool alloys of improved quality are widely used in the production of tools used to process metals: cutters, drills, countersinks.

The use of carbon steel with low and medium carbon content has found application in the construction of metal structures and communications. Special rolling mills of metallurgical plants produce various profiles that are constantly in demand:

• corners;
• channels;
• pipes;
• I-beams;
• other, including custom, types of profiles.

All industries widely use sheet metal, which differs in size, quality and thickness of manufactured products.

Using the specific properties of carbon steels, they are used in various fields of the national economy. Knowledge of the specific differences between certain alloys will allow you to competently and technologically apply the required material in the right place.

Source: https://prompriem.ru/stal/uglerodistaya.html

What is the difference between carbon and alloy tool steels and ordinary steels | mk-soyuz.rf

In carbon tool steels, when the melting process occurs, carbon and certain elements are used. The composition of the steel depends entirely on the product in which the steel will be used. That is, a specific type of steel is suitable for its activity.

The added elements can result in qualities such as:

• Fluidity.
• Hardness.
• Plastic.

Adjustment of each quality is obtained through the percentage of carbon in the steel composition. Its percentage of the total volume is considered the main condition for dividing steel into types. The carbon percentage indicates the hardness level of the product. The higher the carbon level, the higher the strength of the product, but the product becomes more brittle. Steel has several types:

• Low carbon. Includes up to 0.25% carbon. It has good ductility and is easily deformed not only at high temperatures, but also at cold ones.
• Medium carbon. Has 0.3-0.6% carbon. It has a sufficient level of strength, while maintaining its level of ductility and fluidity, therefore it is well processed.
• High carbon. Has 0.6-1.4%. Suitable for heavy-duty instruments and measuring instruments.

This type of steel contains almost no alloying additives. They differ in their determination of the minimum basic impurity. Of the impurities, the additions of magnesium, manganese and silicon can be called basic.

Marking of carbon tool steel

Carbon tool steels are marked as follows:

• Y7
• Y7A
• Y8
• Y8A
• Y9A
• Y10
• Y11
• YNA
• Y12
• Y12A
• Y13
• Y13A

The letter “U” means that the steel is carbon, and the numbers indicate the carbon content as a percentage, which is increased tenfold. If there is the letter “A”, it means that the steel has a high level of quality.

Steel, which contains high quality, differs in chemical composition from high-quality steel in a reduced concentration of impurities such as sulfur and phosphorus. There are certain points in carbon steels that make its use limited, these are:

• High thermal expansion coefficient.
• Low electrical properties.
• Low resistance to corrosion in aggressive environments at high temperatures.
• Decrease in strength level at higher temperatures.
• Sensitive to overheating.
• Low resistance of martensite during tempering.

Everything suggests that the tools are capable of working only at low cutting speeds.

Application of carbon tool steel

It is important to know where carbon tool steel is used so that there is an understanding of its properties. It is used in the manufacture of forging, metalworking, stamping and metal-cutting tools.

U7, U7A

• Used in woodworking. Axe, cleaver, chisel, chisel.
• Small pneumatic tools.
• Chisel, crimp, striker.
• Blacksmith stamp.
• Needle wire.
• Mechanical and installation tools.
• Hammer, sledgehammer, gouge, screwdriver, combination pliers, needle nose pliers, side cutters.

U8, U8A, U8G, U8GA, U9, U9A

• In the manufacture of tools that work in conditions where there is no heating of the cutting edge.
• Wood processing. Milling cutter, countersink, forging, axe, chisel, chisel, rip saw and circular saw.
• Knurling roller, plates and rods for lithium molds under pressure of tin and lead alloys.
• For locksmith and assembly tools. Rivet crimper, center punch, punch, screwdriver, combination pliers, needle nose pliers, side cutters.
• For calibers of simple shapes and low accuracy classes.
• Cold-rolled heat-treated tapes, 2.5-0.02 mm thick, which are needed to create flat and coiled springs and spring parts with complex configurations, valves, probes, reeds, splitting knife lamellas, small structural parts, including watches.

U10A, U12A

• Core.
• Needle wires

U10, U10A, U11, U11A

• In the production of tools that work in conditions that do not cause heating of the cutting edge.
• Woodworking. Hand cross-cut saw, carpenter's saw, machine carpenter's saw, twist drill.
• Cold forging stamp of small sizes without section transitions.
• Caliber of simple shapes and low accuracy class.
• Knurling roller, file, metal scraper, etc.
• A file, a scraper of cold-rolled heat-treated tapes with a thickness of 2.5-0.02 mm, which is used in the manufacture of flat and twisted springs, as well as spring parts with a complex configuration, valves, probes, reeds, splitting knife lamellas, structural small parts, including watches.

U12, U12A

• For tap, file, bench scraper.
• Cold forging stamps, cut and die-cutting of small size without cross-sectional transition, cold heading punch and stamp of small size, caliber of simple shapes and reduced accuracy class.

U13, U13A

• For the production of tools with reduced wear and moderate, as well as significant specific pressure (without heating the cutting edge).
• Files, razor blades and knives, sharp surgical instruments, scrapers, engraving instruments. Steel tool.

Carbon and alloy tool steels are affordable and effective materials. They do not bypass any of the industries that use manual or automatic tools. The price-quality ratio makes this material the most accessible and, in some ways, even irreplaceable.

Source: https://xn----ntbhhmr6g.xn--p1ai/metallyi/chem-otlichayutsya-instrumentalnyie-uglerodistyie-stali-ih-markirovka

How do carbon steels differ from alloy steels?

Carbon steel is a metallurgical composition with a low content of additives and a high iron content - up to 99 ½%. This material is in high demand in various industries, which explains its high share in production - up to 80%.

Today, about 2 thousand brands have been developed. The structure of a material depends on its carbon content. By changing the percentage you can influence characteristics such as hardness, fluidity, ductility and density.

The carbon content of the material is critical at 0.8%.

Regarding this indicator, the US is distinguished:

• if C is less than 0.8%, ferrite and pearlite are present in the structure of the material;
• at a C (carbon) content of 0.8%, the material is characterized by a pearlite structure;
• when the C content is more than 0.8%, cementite appears in the structure.

The general trend with increasing C content is expressed in an increase in strength, impact strength and cold brittleness threshold, but the ductility of rolled products decreases.