What is tool steel

Tool steels: AISI classification

According to the standardization of the American Iron and Steel Institute (AISI), tool steels are divided into the following main series: 1) “W” steels - carbon, water-hardened; 2) “L” steels - low-alloy; 3) “S” steels - impact-resistant; 4) steel “O” - with quenching in oil; 5) steel "A" - with quenching in air; 6) steel "D" - high-carbon, high-chromium; 7) steel "H" - with high hardness, heat-resistant;8) steel "H" - with high hardness, heat-resistant;8) steel “M” - high-speed steel alloyed with molybdenum;

9) steel “T” - high-speed steel alloyed with tungsten.

American Tool Steels (AISI)

Each of these types of tool steels is further subdivided into specific steels. In the designation of steel, a number is added to the letter, for example, W2. Each such series of steels includes up to tens, sometimes more, of different steels. For example, the W series includes steels from W1 to W7. In Table 1, for clarity of classification, 1-2 representatives of all series of tool steels with an average chemical composition are presented.

Table 1 – AISI classification of tool steels (average chemical composition)

tool steels for wear resistance, toughness and heat resistance

The most important properties of tool steels are wear resistance, toughness and heat resistance. Table 2 shows the ratings of these three basic properties for each of the steels listed in Table 1. This rating is a number from 1 to 10, with 10 being the highest rating.

Table 2 - wear resistance, toughness and heat resistance of tool steels

In general, the main “levers” for achieving a high level of the three main properties of tool steels come down to the following: 1) higher wear resistance - more carbides; 2) higher toughness - lower carbon content;

3) higher heat resistance - more alloyed carbides.

“W” series tool steels

The letter "W" denotes water quenching. These steels are similar to ordinary carbon steels and have very low hardenability. As shown in Table 2, the toughness of this steel increases when the steel is case hardened.

This means that the steel is hardened at a rate that ensures martensite forms only near the surface, allowing the core to remain unhardened and therefore tough. The low heat resistance compared to other steels is due to the fact that other steels contain alloyed carbides such as M3C rather than regular Fe3C.

Alloy carbides resist coarsening and dissolve at high temperatures, which gives steels increased heat resistance.

The last column of Table 1 indicates the total content of alloying elements in steel. This total content of alloying elements increases as you move across the table from top to bottom. This means that the volume fraction of carbides also increases.

“L” series tool steels

The letter “L” comes from the word “low” in this series - all these steels are low-alloy steels and are similar to ordinary low-alloy steels. For example, L6 steel is very similar in essence to 4340 steel, with a carbon content of 0.4 to 0.7%.

“S” series tool steels

The letter “S” for these steels comes from the word “shock” - shock, since they are all impact resistant. The high toughness required for impact resistance is achieved by reducing the carbon content of these steels to very low levels. However, this is also the reason for the low wear resistance and heat resistance characteristic of these steels.

“O” series tool steels

The letter “O” in the designation of these steels comes from the word “oil” - oil, since all of them are hardened by cooling in oil. Key alloying elements in Table 1 are highlighted in green. In steels of the “O” series these are manganese and vanadium. These elements give "O" steels increased hardenability compared to "W" series steels, allowing them to be hardened by oil cooling.

“A” series tool steels

The letter "A" stands for air hardening. The hardenability of these steels has been improved to such an extent that they are capable of hardening when cooled in air. The key alloying elements that provide high hardenability are chromium and molybdenum.

“D” series tool steels

These steels are called high-carbon and high-chromium steels. Steels can be hardened in air. As can be seen in Table 2, the combination of high carbon content with high alloying element content provides high wear resistance, fairly high heat resistance, but very low toughness.

Tool steels of the “N” series

The letter “H” here stands for “hot hardness” - maintaining hardness at elevated temperatures, heat resistance. These steels are usually used to make dies and other pressing tools for hot pressing of aluminum and its alloys. The combination of low carbon content and fairly high alloying element content gives good toughness and heat resistance, but very moderate wear resistance.

Tool steels of the “M” and “T” series

The letters "M" and "T" stand for molybdenum and tungsten (tungsten) in these high-speed steels. Both carbides of these elements are stable up to very high temperatures.

Therefore, high levels of these alloying elements give a large volume fraction of carbides in these steels. This provides them with good wear resistance and heat resistance, but low viscosity.

T15 high carbon steel provides an example of how tool steels are designed to maximize wear and heat resistance at the expense of toughness.

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2. MARKING OF STEEL ACCORDING TO RUSSIAN STANDARDS 2.1. Marking of structural steelsStructural carbon steels. In terms of application, carbon structural steels are classified as general purpose steels. They are produced in ordinary quality and high quality, the markings of which vary. Carbon structural steels of ordinary quality are marked with a combination of the letters “St” and a number (from O to 6): StO, St1, St2, St6. The degree of deoxidation is indicated by adding the letters “sp” to calm steels, “PS” to semi-quiet steels, and “kp” to boiling steels. For example, StZsp, St4ps, St1kp. Calm and semi-calm produce St1-St6, boiling St1-St4. STO steel is not classified according to the degree of deoxidation. The number in the steel grade indicates a conditional number. With an increase in the standard number of the steel grade, the carbon content increases (from 0.06% to 0.49%), the concentration of manganese (from 0.25% to 0.8%), and the tensile strength (Ov), yield strength (ao.) increases accordingly. 2) and plasticity decreases (5,f). Steels with a high manganese content (up to 1.1%) are also produced, for example, StZGps. For ordinary quality steels, the chemical composition and degree of deoxidation during smelting are regulated by GOST 380-94, mechanical properties - GOST 535-88. High-quality carbon steels are produced with guaranteed chemical composition and mechanical properties (GOST 1050-88). They are marked with two-digit numbers; 08, 10, 15, 20,,85, 5 indicating the average carbon content in hundredths of a percent. For example, steel 10 contains -0.1% C, steel 45 - on average 0.45% C. As a rule, these steels contain no more than 0.8-0.85% C. Quiet steels are marked without an index, semi-quiet and boiling steels with the index “PS” or “kp”, respectively. They produce boiling steels 08kp, 10kp, 15kp, 20kp, semi-calm steels - 08ps, Jups, 15ps, 20ps. Unlike calm steels, boiling steels practically do not contain silicon (no more than 0.03%), in semi-quiet steels its amount is limited to 0.05-0.17%. Structural alloy steels. Alloy steels are produced and supplied in quality and high quality. By application, alloy steels can be for both general and special purposes. This group of steels is the most numerous; their marking is regulated in accordance with GOST 4543-88. An alphanumeric system has been adopted for marking alloy steels, by which their chemical composition can be determined. The number at the beginning of the stamp shows the carbon content in hundredths of a percent. The letter designations correspond to one or another alloying element (Table 1), and the number after the letter indicates the approximate content of the alloying element as a percentage. If there is no number after the letter, then the concentration of this alloying element is less or about 1-1.5%. For example, steel 20KhNZ contains on average 0.2% C, up to 1.5% Cr, 3% M|, steel 08Kh18T contains 0.08% C, 18% Cr and less than 1.5% T|. It should be remembered that elements such as manganese and silicon can be both useful impurities and alloying elements in steel. If the Mn content does not exceed 0.8%, and 31 - 0.37%, then they are impurities and are not indicated in the steel grade. To designate high-quality steels containing a reduced amount of harmful impurities compared to high-quality ones, the letter “A” is used, placed at the end of the steel grade, for example, 12Х2Н4А.2.2. Marking of tool steelsCarbon steels. Carbon tool steels (GOST 1435-90) are produced in high-quality U7, U8, U9, U13 and high-quality U7A, UZA, U9A, U13A. The letter “U” in the brand indicates that the steel is carbon, and the number indicates the average carbon content in tenths of a percent. For example, UZ steel contains 0.8% C, and U12 steel contains 1.2% C. Tool steels are usually high-carbon (carbon >0.7%). Tool alloy steels. The marking of tool alloy steels, like structural steels, consists of a combination of numbers and letters indicating the chemical composition of the steel. The first figure shows the average carbon content in tenths of a percent, if its content is less than 1%. If the carbon content is greater than or equal to 1%, then the figure is missing. The letters indicate alloying elements (see Table 1), and the numbers following them indicate the content of the corresponding alloying element in whole percentages. For example, 9ХС steel contains 0.9% C, up to 1.5% Cr and up to 1.5%3|, KhVG steel contains 1-1.5% C, 1-1.5% each of chromium, tungsten and manganese . The grade of high-speed steel begins with the letter “P”, which means the presence of an average of 0.8% carbon, 4.2% chromium and 1-2% vanadium. The number following the letter indicates the average content of the main alloying element of high-speed steel - tungsten (in percent). The average content of molybdenum (in percent) in steel is indicated by the number after the letter “M”, cobalt - by the number after the letter “K”, vanadium - by the number after the letter “F”, etc. For example P18, P6M5, P9M4K8. So, in addition to C, Cr and V, the latter steel contains 9% \L/, 4% Mo, 8% Co. 2. Theoretical and real strength of crystalline materials. Ticket No. 7. 

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Topic 6. Structural and tool steels

Classification and purpose of structural steels. Carbon quality and ordinary quality steel. Alloyed structural steels. Cementable and temperable steels, their properties and applications. Spring and ball bearing steels. Steels with increased machinability. Steels for gears, shafts, chassis parts and brake systems. High-alloy corrosion-resistant, heat-resistant and scale-resistant steels. Classification and marking of tool steels. Steels for cutting, stamping, medical and measuring instruments. Hard alloys, their properties and purpose. Heat treatment of tools. Selection of steel grades for tools, taking into account operating conditions. Methodological instructions. Structural steels are alloys intended for the manufacture of machine parts and products of the construction industry. In addition, this group also includes steels with special properties - wear-resistant, corrosion-resistant, heat-resistant, spring, etc. Carbon steels of ordinary quality are produced in grades St.0, St.1,¸ St.6. in accordance with GOST 380-71. Such steels are mainly used in construction, as they have good weldability and sufficient strength. High-quality carbon (GOST 1050-74) and alloy (GOST 4543-71) steels are used in mechanical engineering and other types of industry. Steels of this class are subjected to thermal and chemical-thermal treatment to impart the required physical and mechanical properties to products. The presence of alloying elements (up to 10%) in steel provides high strength and ductility and makes it possible to use them for highly loaded machine parts. High-alloy steels (alloying element content more than 10%) have a special purpose - corrosion-resistant, scale-resistant, non-magnetic, etc. To improve machinability by cutting, sulfur, selenium, lead and calcium are additionally introduced into the steel. sulfur and lead up to 0.3%, selenium and calcium up to 0.05% can increase the durability of the cutting tool by 2 times, but their presence reduces the properties of steel. Therefore, the use of such steels is not recommended for parts operating in a complexly stressed state. Increasing the resistance of steel against corrosion is achieved by introducing chromium into it, which forms a dense oxide film on the surface of the Cr2O3 type. This group includes steels with a chromium content of more than 12%. Tool steels have high hardness, wear resistance and strength. They are used for cutting tools, cold and hot forming dies, measuring tools of various sizes and shapes. Steels for cutting and stamping tools must have heat resistance, that is, maintain high hardness and strength when heated to high temperatures. In this regard, non-heat-resistant, semi-heat-resistant and heat-resistant steels are distinguished. For tools subject to heating up to 200°C in operation, carbon and low-alloy steel grades are used - U8, U10, U13, 9ХС, 11Х, etc. Semi-heat-resistant steels are mainly used for hot deformation dies, the working edge of which is heated to 400-500°С. These are steels alloyed with chromium, molybdenum, tungsten and vanadium, such as 4Х5МФС, 3Х3ВМФ, 5ХНМ, 5ХНВ, etc. When the tool is heated during operation to 600-800°C, high-speed steels of type R9, R18, R6M5K5, etc. are recommended for its manufacture. Main alloying the element of such steels is tungsten, which forms a stable carbide. The properties of tool steels are achieved through heat treatment, quenching and tempering. Literature: [1, 252-313; 3, 364-508; 6, 73-135; 6, 143-174].Questions for self-test.1. Is it possible to use boiling steel for products operating at temperatures below –40°C?2. How to explain the good machinability of steel alloyed with S, Pb, Ca?3. What requirements must steel have for cold forming?4. What heat treatment does steel 40KhN, 40Kh, 38KhMYuA, 42KhMFA undergo?5. What steels are used for work in oxidizing and other aggressive environments?6. What are the steel grades for springs, springs and bearings? What types of heat treatment are they subjected to?7. What are the advantages and disadvantages of carbon steels for cutting tools?8. Specify steels for cold and hot deformation dies. Consider the heat treatment and resulting properties of these steels.9. What are the requirements for steels for measuring instruments and indicate ways to achieve stability of structure and properties during operation? infopedia.su

Structural and tool carbon steels. Marking, application

Source: https://pellete.ru/stal/instrumentalnye-i-konstrukcionnaye-stali.html

Characteristics and grades of tool steels

Wear-resistant tools and parts, the strength of which is subject to increased demands, require the use of tool steels, which have a number of important differences from structural steels.

Round tool steel blanks

Areas of application of tool steels

Tool steel is an alloy with a carbon content of at least 0.7%. Its structure can be hypoeutectoid, ledeburite or hypereutectoid.

Tool steels with different structures are distinguished by the presence of secondary carbides. There are no secondary carbides in alloys with a hypoeutectoid structure.

Meanwhile, in each of these structures, carbides are necessarily present: they are formed during eutectoid modifications or are the result of the decomposition of martensite.

Scheme-classification of instrumental materials

In modern industry, tool steels are widely used. They are used to produce:

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

Depending on the area of ​​application of tool steels, certain requirements are imposed on them. However, there are compliance criteria common to all brands:

• a sufficient level of viscosity (this characteristic is especially relevant for parts subject to shock during operation);
• high strength;
• wear resistance;
• high level of hardness.

Options for using tool steels (using carbon as an example)

Name Steel grade Application

Carbon instrumental	У7У7А	Hammers, cores, screwdrivers, chisels, blacksmith tools, scythes
Carbon instrumental	У8У8А	Scissors, chipper knives, hand carpentry tools, frame saws
Carbon tool, high hardness	У10У10А	Drills, small diameter cutters, band saws, reamers
Carbon tool, increased hardness	У12У13	Wood turning tools, metal hacksaw blades, needle files, files, engraving tools

Brands of alloys intended for use in cold deformation conditions must, in addition, have a smooth working part, the ability to retain size and shape, and also have different yield and elasticity strengths. And tool steel, suitable for work under conditions of hot deformation, must have high thermal conductivity, resist tempering and be resistant to temperature fluctuations. The grades of steel used for the production of cutting tools must also meet special requirements.

Requirements for tool steels

All carbon tool steels are subject to the following requirements:

• good machinability by metal cutting;
• low sensitivity to overheating;
• low susceptibility to the processes of adhesion and welding to workpieces;
• good grindability;
• susceptibility to calcination;
• hot plasticity;
• ability to resist decarbonization;
• resistance to cracking.

Types of tool steels

All grades of steel for the production of tools are divided into 5 main groups.

Heat resistant and viscous

As a rule, these are hyper- and hypoeutectoid steels, which contain molybdenum, tungsten and chromium. carbon in such alloyed tool steels corresponds to medium and low values.

Highly hard and viscous, non-heat resistant

Such alloys are distinguished by a low content of alloyed elements and a medium content of carbon. They are also characterized by low hardenability.

High hardness, heat resistant and wear resistant

These grades include high-speed alloy steels (the content of alloying elements in them is very high), as well as alloys with a ledeburite structure containing more than 3% carbon.

Wear resistant, high hardness and medium heat resistance

These are steels with a hypereutectoid and ledeburite structure, which contain 2-3% carbon and 5 to 12% chromium.

High hardness and non-heat resistant

The composition of such tool steels with a hypereutectoid structure either does not contain alloyed elements at all, or contains them in insignificant quantities. The level of hardness of such alloys is ensured by the large amount of carbon in their composition.

Classification of tool steel in the form of a diagram

An important parameter of tool steels is their level of hardness. As a rule, it is undesirable to use high-hardness steels for the production of tools that are subject to shock loads during operation. This is explained by the fact that such alloys have low viscosity and significant fragility, which can lead to breakage of the tool that is made from them.

Based on the level of hardness, two categories of tool steels can be distinguished:

• with a high level of viscosity (carbon content in the range of 0.4-0.7%);
• with high wear resistance and hardness (they contain more carbon: 0.7-1.5%).

High hard steel hydraulic hammer part

Steel grades are also classified according to the degree of their hardenability. According to this criterion, alloy steels with increased (possible hardening diameter 80-100 mm), high (50-80 mm) and low (10-25 mm) hardenability are distinguished.

About marking of tool steels

To determine the type of tool steel, knowledge of the markings is required, which includes both alphabetic and numerical designations. It's not difficult to figure this out. Very often the letter “U” is found in the marking of alloys.

It means that this is carbon steel. The numbers following this letter indicate the carbon content in the alloy, calculated in tenths of a percent.

The letter “A” is also found in the marking of carbon tool steels, indicating that the alloy is high-quality.

Marking of tool steel (using carbon as an example) indicating the content of additional elements

A large category of tool steels consists of high-speed alloys, which are designated by the letter “P”. This letter is followed by numbers that can be used to determine the content of the main alloying element for steels of this category - tungsten.

the remaining elements in the composition of high-speed alloy steels (molybdenum, vanadium and cobalt) are determined by the numbers following the corresponding letters in their markings - “M”, “F” and “K”. The composition of high-speed alloys must include chromium, but its amount is determined by default - no more than 4%.

Very often, the marking of tool steels begins with a number (for example, 9ХС, 9Х, 6ХГВ), which indicates the content (in tenths) of carbon in their composition, if it does not exceed 1%. If the alloy contains about 1% carbon, then the number at the beginning of their marking is not placed at all. The content of the remaining elements (in whole fractions) is indicated by the numbers that appear in the markings behind the letters indicating the corresponding alloying element.

Quenching and tempering of carbon tool steels

GOST 1435 specifies both the composition of carbon steels and their main characteristics. carbon in such alloys (which can be determined by their grade) ranges from 0.65 to 1.35%.

In order to obtain the optimal structure and required hardness, these alloys are annealed before tool production begins. In this case, for tool steels with a hypereffectoid structure, spherodizing type annealing is performed.

Heat treatment carried out using this technology leads to the appearance of granular cementite. And the cooling rate, which can be easily adjusted, allows you to obtain grains of the required size.

Steel hardening production process

After the tool is manufactured, the tool steel is subjected to hardening and subsequent tempering. This makes it possible to obtain a material of the required hardness. It is also quite easy to regulate the hardness of the finished tool; this is achieved by selecting a certain temperature for the tempering operation.

Thus, for tools that are subjected to systematic shock loads during operation, the optimal hardness is from 56 to 58 HRC, which is obtained by tempering at a temperature of 290 degrees Celsius. The most stringent requirements are imposed on the hardness of dies, engraving devices, and files (62-64 units on the HRC scale). It is achieved by tempering at a temperature of 150 to 200 degrees Celsius.

Hardening increases the hardness of carbon steels for the reason that it is with its help that it is possible to obtain the optimal structure of the alloy of iron and carbon. Variants of this structure:

• carbides with martensite;
• only martensite.

Tool die steel

Metal products produced by deformation can be processed in a heated or cold state. Accordingly, the dies with which such parts are processed can be cold- or hot-deformed. Naturally, the production of different types of dies requires the use of different grades of tool steel.

Thus, for dies of cold-deformed type and small thickness (up to 25 mm), carbon steels U10, U11 and U12 are used.

The hardness of alloys of these grades ranges from 57 to 59 HRC units; they are distinguished by sufficient toughness, a good level of resistance to plastic deformation, and the ability to withstand wear during operation.

For larger tools (thickness greater than 25 mm), which experience greater loads during operation, steels with a high chromium content (X9, X, X6VF) are used.

Tool die steel in stock

Products that regularly experience shock loads during their operation must have high viscosity (for example, 4ХС4 and 5ХНМ). To ensure that this requirement is met, alloy steels are used in production, the composition of which is enriched with special elements, and the level of carbon content is significantly reduced. In addition, special heat treatment of such tool steels is necessary.

During their operation, hot-deformed dies are subjected not only to significant mechanical but also thermal loads. Naturally, special requirements are imposed on tool steels for the production of these dies (for example, 5ХНМ and 4ХСМФ), such as:

• increased resistance to cracking under conditions of constant heating and cooling of the tool;
• high level of thermal conductivity and hardenability;
• resistance to scale formation.

Source: http://met-all.org/stal/harakteristiki-i-marki-instrumentalnyh-stalej.html

D2 steel for knives, pros and cons, characteristics, processing

Various alloys are used to make cutting tools. The most popular steel for knives is D2, the pros and cons of which cause a lot of controversy. Some experts argue that this is the best option, others do not see anything special in it and believe that its cost is artificially inflated. That is why, when choosing the ideal product, you should understand all the nuances.

Advantages and disadvantages of the material

The D2 marking is used to designate very high quality tool steel. Its composition and production technology were developed in America. According to its characteristics, the material is close to the Russian brand X12MF.

D2 steel, used for making knives, has both advantages and disadvantages. Among its positive qualities it should be noted:

1. A high degree of hardness is the main advantage of the raw material. That is why it holds an edge for a very long time.
2. Excellent resistance to deformation even when exposed to high temperatures.
3. Very sharp cutting edge. This quality is ensured by the carbon contained in the alloy.
4. Affordable price. Knives made from it have an attractive price, which makes them popular among a wide range of consumers.

The main disadvantage of D2 steel is its inability to withstand lateral loads. Disadvantages also include susceptibility to pitting corrosion. But this problem, unlike the first one, can be solved very simply - the knife must be properly and promptly cared for.

You should also know that sharpening tools requires special tools and materials. It is almost impossible to perform it efficiently in field conditions. In addition, the blade cannot be polished completely, so it will always be matte.

Despite all of the above, after a detailed consideration of the pros and cons of steel for d2 knives, it becomes clear that the material still has much more advantages than disadvantages.

The material has a high degree of hardness

Knives made of D2 steel have a very sharp cutting edge.

Disadvantages include the inability to withstand lateral loads

For what types of knives is it used?

Brand D2 is one of the most popular. It is used to make various types of knives:

1. Hunting. The hardness and sharpness of the cutting edge are indispensable when cutting carcasses, skinning, and cutting meat into pieces.
2. Tourist. Knives made of this alloy can easily cope with cutting pegs, branches, opening canned food, chopping bushes, and cutting ropes.
3. Household. A good cut allows them to cope with all tasks. This knife does not need sharpening. To maintain the original thickness of the cutting edge, it is only occasionally corrected.

In addition, D2 steel is used to make razor blades. The characteristics of this brand allow it to be used for industrial purposes.

Due to its high hardness and ability to withstand deformation, it is excellent for creating dies for cold stamping, threading tools, wear-resistant parts, woodworking tools, and molds for casting ceramic products. In the metalworking industry it is used for the manufacture of high-strength metal cutters.

Kitchen

Hunting

Tourist

Chemical composition and processing

D2 steel belongs to the high-carbon alloy group. It includes the following elements:

1. Carbon. Gives strength. The higher its content, the stronger the steel.
2. Manganese. Increases strength characteristics. Used at the smelting stage. Rails and high-strength safes are made from alloys with manganese.
3. Chromium. They are classified as alloying components. Increases corrosion resistance.
4. Molybdenum. Used at the hardening stage. Increases heat resistance and reduces fragility.
5. Vanadium. High hard metal. Increases resistance to aggressive chemical influences.
6. Silicon. Improves strength characteristics.
7. Nickel. It is an alloying additive. It has anti-corrosion properties.
8. Phosphorus. Referred to as technological impurities. When the maximum concentration is exceeded, it makes the alloy brittle and brittle.
9. Sulfur. Included in the group of technological impurities. Reduces strength and toughness.

High-quality alloys contain no more than 0.03–0.06% technological impurities. Exceeding these indicators leads to a significant deterioration in the physical and mechanical properties of the material.

In the production of D2 Steel, the electroslag remelting method is used. Its essence lies in the use of a slag layer. The molten metal is first passed through it, and only then sent for molding. Slag absorbs all impurities and unnecessary elements, including phosphorus and sulfur.

To give steel greater strength, it is hardened. It is very important to ensure maximum uniform heating. Compliance with this condition will avoid warping and create a uniform structure.

Heat treatment consists of several mandatory steps:

1. Forging. During the process, the metal is given the desired shape using heat and pressure.
2. Annealing. The hot part is slowly cooled.
3. Shaping processing.
4. Hardening. The alloy is heated to a critical point and then cooled very quickly. At this stage, the most important characteristic – strength – improves. The steel becomes harder and more wear-resistant.
5. Vacation. The final stage of heat treatment. Improves ductility, reduces brittleness without reducing strength.

For hardening, steel can be heated in several ways. To heat D2, salt baths at a temperature of 850° C are used. The workpieces are completely heated within just a few minutes. After this they are cooled in air. Heat treatment improves the strength characteristics of steel. After this, the knife blanks are subjected to finishing processing. During this process they are polished and sharpened.

To improve the properties of workpieces, experienced craftsmen use the aging procedure. Its essence is heating to a temperature of 100–110°. The blank is kept in this state for several hours, after which it is cooled. Heating is repeated about 10 times. The knife is then polished.

D2 steel combines excellent physical and mechanical properties and affordable cost. With careful use and timely care, knives made from it will last for many years, while maintaining their original strength and sharpness. That is why the brand has become so popular all over the world.

Source: https://posuda-expert.ru/nozhi/populyarnye/243-stal-d2-plyusy-i-minusy

Tool alloy steels

Alloy steels are intended for the manufacture of cutting and measuring tools and, compared to carbon tool steels, have greater hardenability, wear resistance and heat resistance.

Steels for measuring instruments

Measuring tools (tiles, gauges, templates) must retain their shape and dimensions over a long period of time. They should not undergo spontaneous structural transformations that cause changes in the dimensions of the tool during operation.

The linear expansion coefficient should be minimal. Steels with a martensitic structure have these properties. For the manufacture of measuring instruments, steel grades X, X9, XG, X12F1 are used. Quenching is carried out at temperatures of 850870 0C in oil. To eliminate residual austenite after hardening, cold treatment is carried out at minus 70 0C, and then low tempering at 120-140 0C. The hardness after heat treatment is 6364 HRC.

Steels for cutting tools

The main requirements for cutting tools are the following:

1. maintain high hardness and wear resistance of the cutting edge under friction conditions for a long time;
2. have high heat resistance (red resistance), i.e. the ability to maintain high hardness and cutting ability during prolonged heating (resistance to tempering when the tool is heated during operation).

Cutting tools are made from steels with reduced or increased hardenability, or from high-speed steels.

Steels of reduced hardenability include carbon steels U7U13, discussed earlier.

Steels with increased hardenability include alloy steels containing up to 5% alloying elements, grades 9ХС, ХВСГ, 9Х5С.

Like carbon steels, they have low heat resistance - up to 300 0C, but higher hardenability. They are used to make tools for cutting materials of low strength at low speed: hand drills, reamers, dies, etc.

Quenching is carried out at a temperature of 800860 0C in oil, tempering at 150200 0C. The hardness is 6166 HRC.

High speed steels

These include high-alloy steels intended for the manufacture of high-performance tools. The main property of these steels is high heat resistance (red resistance), i.e. preservation of the martensitic structure and high hardness, strength, wear resistance at elevated temperatures that occur in the cutting edge when cutting at high speed.

Heat resistance is ensured by the introduction of a large amount of tungsten together with other elements: molybdenum, chromium, vanadium.

Tungsten and molybdenum in the presence of chromium bind carbon into special carbides such as M6C and MC that are difficult to coagulate during tempering and delay the decomposition of martensite. The release of dispersed carbides, which occurs at elevated tempering temperatures (500-600 0C), causes dispersion hardening of martensite. When tempered, vanadium, released in the form of carbides, enhances dispersion hardening.

Cobalt also helps to increase heat resistance. It does not form carbides, but, by increasing the energy of interatomic bonding forces, it complicates the coagulation of carbides and increases their dispersity.

Due to complex alloying, tools made of high-speed steel retain high hardness up to 640 0C and allow 24 times more productive cutting conditions than tools made of carbon and low-alloy steels.

High-speed steels are designated by the letter P (“rapid” - speed), followed by a number indicating the tungsten content as a percentage. Alloying elements and their content in % are indicated below.

Based on their performance properties, high-speed steels are divided into two groups:

1. normal performance;
2. increased productivity.

Group 1 includes steel grades R9, R18, R12, R9F5, R6M3, R6M5.

They retain a hardness of at least 58 HRC up to a temperature of 620 0C, are better processed by pressure and cutting, and have high strength and toughness.

The 2nd group includes steels containing cobalt and an increased amount of vanadium: R6M5K5, R9M4K8, R9K5, R9K10, R10K5F5, R18K5F2. They are superior to group 1 steels in heat resistance (630640 0C), hardness (HRC ³ 64) and wear resistance, but are inferior in strength and ductility. This group of steels is used for processing high-strength steels, corrosion-resistant and heat-resistant steels with an austenitic structure, and other difficult-to-process materials.

High-speed steels belong to the carbide (ledeburide) class. The structure of cast steel contains a complex eutectic resembling ledeburite and located along the grain boundaries.

To impart heat resistance to the steel, the tool is subjected to hardening and repeated tempering (Figure 51).

a - without cold treatment; b - with cold treatment Figure 51 - Schemes of heat treatment modes for tools made of high-speed steels

The hardening temperature of steel R18 is 12201290 0C, R6M5 is 12101230 0C. High temperatures are necessary for more complete dissolution of secondary carbides and production of highly alloyed austenite.

Due to the low thermal conductivity of steel, during hardening it is heated slowly with heating at 450 and 850 0C. To reduce oxidation and decarbonization, heating is carried out in salt baths (usually BaCl2).

Holding at the quenching temperature should ensure the dissolution of part of the carbides in the austenite within the limits of their possible solubility. To obtain higher hardness of P6M5 steel (63 HRC) and heat resistance (59 HRC at 620 0C), the heating time for hardening is increased by 25%.

To reduce the deformation of tools, stepwise hardening in molten salts at a temperature of 400500 0C is used. Cooling is carried out in oil (small parts can be cooled in air).

After hardening, the maximum hardness of 6HRC steels is not achieved, since the structure, in addition to martensite and primary carbides, contains 30-40% retained austenite (Mk below 0 0C). It reduces the mechanical properties of steel, impairs grindability and dimensional stability of the tool. Residual austenite transforms into martensite when tempered or cold treated.

The tempering is carried out at a temperature of 550570 0C. During the holding process during tempering, dispersed carbides M6C and MC are released from M and Aost.

Austenite is depleted in carbon and alloying elements, becomes less stable and, when cooled below Mn, undergoes a martensitic transformation. Apply two or three times of tempering with exposure for 1 hour and cooling in air.

At the same time, Aost is reduced to 35%. Cold treatment shortens the heat treatment cycle. Structure: tempered martensite and carbides; hardness is 65 HRC.

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Source: https://dprm.ru/materialovedenie/instrumentalnye-legirovannye-stali

Forging from structural steel 180×280 mm art. 40,40A GOST 8479 – KMI Company, LLP

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Wholesale:

• 1.13 AZN/kg – from 10000 kg

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Specifications

• Country of manufactureRussia

Description

A forging made of structural steel is a semi-finished product. Produced by stamping or forging. As a rule, the forging can be either round or rectangular. Most often, its shape and size depend on the final product.

Structural steel forging. Characteristics

• Brand: Art. 40 (40A)
• Size: 180x280 mm
• Standard: GOST 8479

Structural steel forging. Purpose

These forgings are used to make:

• Cylinders.
• Shafts.
• Pipe blanks.
• Plates for stamping.
• Rolls of various rolling types.
• Balls.
• Gears.
• Fastening elements.

Industries of use.

• Mechanical engineering.
• Shipbuilding.
• Atomic industry.
• Mining industry.
• Chemical industry.
• Energy.
• Agriculture.
• Automotive industry.

You can buy forgings made of structural steel at a competitive price from stock and to order directly from KMI Company LLP

The price is determined by the volume of products, payment terms, place and method of delivery. The minimum order amount is 28,000 tenge. Please check with the sales department for the final cost.

Advantages of working with KMI Company LLP

• KAZAKHSTAN METAL INDUSTRIAL COMPANY is part of a large international holding company operating in Russia, Kazakhstan, China, Uzbekistan and Kyrgyzstan for more than 10 years.
• Thanks to our network of warehouses in different countries, we offer the most favorable conditions for purchasing rolled metal products.
• We have created an extensive system of working with the largest manufacturers of metal products and have streamlined logistics so that you save time and money.

This price list is for informational purposes only and under no circumstances is it a public offer as defined by the provisions of Art. 447 of the Civil Code of the Republic of Kazakhstan.

Contact the seller

Source: https://az.all.biz/pokovka-iz-konstrukcionnoj-stali-180x280-mm-st-40-g3117000KZ

Characteristics and classification of tool steels

Tool steel is distinguished by the fact that it contains more than 0.7% carbon. Its main difference is its increased strength and hardness, which is why it is used in the production of a variety of working tools.

Due to its low price and high hardness of the alloy, this material is most in demand. However, it has a certain drawback - it is a low level of wear resistance. Therefore, the alloy is not used in the production of automotive parts and equipment that is subject to constant load.

The division takes place into high-quality and high-quality types. The difference is that high-quality steel contains 0.03% sulfur and 0.035% phosphorus, and high-quality steel contains 0.02% sulfur and 0.03% phosphorus.

According to GOST, the following are allowed to be released:

• U7.
• U8.
• U8G.
• U9.
• H10.
• U11.
• U12.
• U13.
• U7A.
• U8A.
• U8GA.
• U9AYU
• U10A.
• U11A.
• U12A.
• U13A.

Among high-quality instrumental instruments, most often there are those that do not have the letter “A”, because this is related to a high-quality brand. The letter "U" stands for carbon content. The number following it indicates tenths of a percent of the carbon contained in this brand. When the letter “G” is located after the numbers, this means that the alloy contains manganese.

There is a classification into three types:

• Carbon.
• Alloyed.
• High-speed cutting (this also includes stamping).

Carbon

Carbon tool steel loses its strength when heated, so they are used in the manufacture of tools that operate at low speed, under simple cutting conditions. This is due to the fact that during friction the temperature does not exceed 200 °C. It is usually used to create a drill, file, tap, and reamer. Because its weldability index is low, it is not used for welded structures.

Alloyed

The alloy type of tool steel contains a slightly different composition. It contains additives of manganese, nickel, copper and other elements. Due to them, the characteristics of the metal are improved. Marking will be mandatory here, since it requires indicating the presence of elements in letters:

• When manganese is added - G.
• Chrome - X.
• Vanadium - F.
• Silicon – S.
• Wolfram - V.
• Copper - D.
• Nickel - N.
• Titan - T.
• Molybdenum - M.

Read also: Pickling stainless steel. Indications. Etching methods.

Numbers may appear after the element designation. The numbers indicate the capacity of the specified element in %. When the figure is missing, the amount will be about 1%.

When alloy tool steel is designated, the amount of carbon is indicated first, which is expressed in tenths of a percent. For example, if we take the 6ХС marking, then there will be 0.6 carbon and 1% chromium and silicon.

scope of application is cutting and stamping tools. This is also not a very suitable option for welded structures.

High-speed

High-speed steel is first marked with the letter “P”. Next comes a number that indicates the tungsten mass fraction. After this come the letter designations of the elements contained in the alloy:

• Molybdenum - M.
• Vanadium - F.
• Cobalt - K.
• Nitrogen - A.

Next come the digital designations of the mass fraction. In some cases, the marking may contain the letter “Ш”, which means “electroslag remelting”. When labeling, the proportion of chromium is not indicated. The same applies to the mass fraction of molybdenum, when it does not exceed 1%.

This type is well suited for cutting tools that experience strong heating during friction (from 600 – 6500 °C). It does not lose hardness and is not subject to deformation. In addition, high-speed tool steel has good capabilities for electric butt welding with grades 45 and 40X.

Processing of tool steels

Processing methods include the following:

Hardening

Hardening is a heat treatment of tool steels, during which the material is heated to an optimal temperature, maintained at the temperature, and then instantly cooled to obtain a nonequilibrium structure. After hardening, the product’s hardness and strength increase and the ductility of the metal decreases. The main quality parameters of hardening tool steel are the heating temperature and cooling rate.

Welding

Welding of tool steel has always been considered one of the most difficult types. For this purpose, electrodes are used that are intended for welding tool steel.

Tool steel differs significantly from other types of steel due to the fact that it contains a large amount of carbon. It is worth remembering that a brand that is not able to withstand high temperatures is not suitable for welding.

That is, carbon steel is not suitable for welding. Alloy metals are best suited for this.

Vacation

The next stage after hardening is tempering. This is required to relieve the stress of brittle martensite that forms during hardening, and also to reduce the content of retained austenite. Most tool steel has a fairly wide tempering temperature range.

It is recommended to use the highest tempering temperature, as this will give the tool strength. The material should cool to a temperature of 65 degrees, and then to room temperature between and after holidays.

There is also multiple tempering, which is used for most complex alloy tool steels.

Stamping

To process tool steel, stamping is used. There are 2 types of stamping:

• In which deformation of the metal occurs in a cold state.
• In which deformation of the metal occurs in a hot state.

When stamping occurs in a hot state, the metal affected by the approaching halves of the die begins to deform and fill the internal cavity of the die. Stamping improves surface quality and shape accuracy.

Each stage should be carried out only by specialists in their field. This is important, since violation of production technologies does not guarantee the declared qualities of the product, therefore it is important to carefully select a supplier.

Tool steel, in some ways, is a convenient and irreplaceable material, which is why its use is widespread throughout the world. This is due to the fact that the hardness of tool steel is suitable for the production of many working tools.

Source: http://solidiron.ru/steel/kharakteristiki-i-klassifikaciya-instrumentalnykh-stalejj.html

Tool steels

We always have a wide range of products at the best prices - in particular, tool carbon steels, which we supply to all regions of Russia.

In accordance with GOST 1435-99, carbon steels are divided according to chemical composition standards into blanks, wire, ingots, strip, sheet, and so on. This GOST is applicable to any metal products made of carbon steel (unalloyed tool steel): with special surface finishing, calibrated, forged strips and rods of various sizes, coils, strips and hot-rolled rods.

Carbon steel differs in carbon content, and, depending on its composition, can be used to manufacture different products. According to GOST 1435-99, steel marked U is produced. GOST includes steels: U7, U8, U8G, U8A, U8GA, U9, U9A, U10 and so on up to U13 - the letter “A” at the end of the name means that this product has higher quality and percentage of carbon content.

This product is not used for welding, and is used mainly for the manufacture of tools (screwdrivers, files), the operating temperature of which is not higher than 2000C.

From our warehouses in the shortest possible time you can purchase any steel from the range:

• hot-rolled strips (according to GOST 103-76),
• calibrated circles (GOST 7417-75),
• forged strips (GOST 4405-75),
• hot rolled circles (GOST 2590-88),
• calibrated hexagons (GOST 8560-78),
• hot rolled squares (GOST 2591-88),
• calibrated squares (GOST 8559-75).

Alloyed tool steels (including die steels)

According to GOST 5950-2000, alloy tool steels come in the following markings: 8Х2В2МФС2, 11Х4В2МФ3С2, 7ХГ2ВМФ, 9Х5ВФ, 3Х2МNF, 5Х2МNF, 4ХМНФС, 4Х3ВМФ, 3ХЗМ3Ф, 13Х, 8ХФ, 9ХФ, 11ХФ , 11Х, 9ХФМ, 8Х6НФТ, 85Х6НФТ, 6Х4М2ФС, Х6ВФ, steel Х12МФ, Х12Ф1, 05Х12Н6Д2МФСГТ, Х, 9Х1, 12Х1, 120Х, 5ХНВС, 7Х3, 8Х3, 6ХС, 9G2F, steel 9ХВГ, 6ХВГ, 4Х4ВМФС, 4Х5МФ1С, 4Х2В5МФ, 5Х3В3МФ S, 6ХВ2С, 5ХВ2СФ, 6Х3МФС6Х6В3МФС, Х12, 40ХСМФ, 9ХС, V2F, KhGS, 4KhS, KhVSGF, 4Kh5MFS, KhVG, Kh12MF, Kh12F1, KhVG, 5KhNM, steel 5KhNV4KhMFS, 4Kh5V2FS.

The first numbers in the designation refer to the percentage of carbon in the material, and if the percentage is close to unity, then these numbers may not be indicated. The letter composition means the alloying element, for example, X - chromium, F - vanadium, and so on.

GOST 5950-2000 in terms of standardization of chemical composition applies to the following metal products: sheets, pipes, blooms, strips, ingots, forgings, slabs, billets, steel grades 9KhFM, 3Kh2MNF, 4KhMNFS and the like.

The document standardizes compliance with the characteristics (including tungsten, chromium, manganese content) of products: calibrated and hot-rolled rods and coils, rods coated with alloy tool steel , hot-rolled strips, forged rods and strips.

Die steels according to GOST include the following grades: 4Х5МФС, Х12МФ, Х12Ф1, as well as 9ХС, 4Х5МФС and the like. Interchangeable steels: 9ХС and ХВГ, 9ХС and 65Г.

Application of alloy tool steels

This type of steel is not intended for welded structures. It is used in the production of cutting tools: cutters, broaches, taps, dies, drills and the like. Alloy steel is also used to create more critical tools for which a carbon tool alloy is not suitable.

The range includes:

Source: http://gkstal.ru/katalog_metalloprokata/specstali_splavy/instrumentalnye_stali

What is tool steel?

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.

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://varimtutru.com/instrumentalnaya-stal-chto-eto-takoe/