Where is carbon tool steel used - Metals and their processing

What is the difference between carbon and alloy tool steels and ordinary steels?

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.

Read also: What are structural alloy steels

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.

Read also: Passivation of stainless steel to combat rust

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: http://solidiron.ru/steel/chem-otlichayutsya-instrumentalnye-uglerodistye-stali.html

Tool steels

Divided into:

Instrumental carbon;
Tool alloyed;
Tool high-speed.

The range of tool steel must correspond to:

hot-rolled round - GOST 2590-88;
hot-rolled square - GOST 2591-88;
forged round and square - GOST 1133-88;
forged strip - GOST 4405-75.

Manufactured in accordance with GOST 1435-74.

Tool carbon steel is marked with the letter U, which means “carbon,” and a number indicating the carbon content in tenths of a percent. If the steel is of high quality, then the letter A is placed at the end of the mark. For example: U12A contains 1.2% C and is a high quality steel.

Brands: U7, U8A, U9, U10A, U11, U12 and U13.

Purpose: intended for the manufacture of tools (drills, taps, reamers, files, etc.) operating under relatively light cutting conditions (low speeds, tool heating temperature not higher than 200°C). The disadvantage of carbon tool steels is their low heat resistance, i.e. rapid softening when heated.

Weldability: tool carbon steel is not used for welded structures.

Tool alloy steel (including die steel)

Manufactured in accordance with GOST 5950-2000.

Brands: 9ХС, ХВГ, Х12МФ, Х12Ф1, 4Х5МФС, 5ХНМ, etc.

Steels Kh12MF, Kh12F1, 4Kh5MFS belong to the category of die steels. Letters and numbers in the designation of brands mean: number - average carbon content in tenths of a percent, X - alloyed with chromium, B - alloyed with tungsten, G - alloyed with manganese. The amount of chromium, tungsten, manganese in steel is determined by GOST.

Steels 9ХС and ХВГ are interchangeable. Steel 9ХС is a substitute for grade 65G.

Purpose: used for the manufacture of cutting tools (taps, drills, dies, reamers, cutters, broaches), as well as stamping tools for more critical purposes than those made from carbon tool steels.

Weldability: tool alloy steel is not used for welded structures.

Tool high speed steel

Manufactured in accordance with GOST 19265-73.
Brands: R18, R6M5, R9K5, etc. The letters and numbers in the designation of brands mean: P - high-speed, number - tungsten content in tenths of a percent, M, K - alloyed with molybdenum or cobalt, respectively, their quantity is determined by GOST.

Purpose: high-speed steels are most typical for cutting tools. They combine high heat resistance (600-6500C depending on composition and processing), high hardness and wear resistance at elevated temperatures and increased resistance to plastic deformation.

Weldability: when electric butt welding with steel 45 and 40X, weldability is good.

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Source: http://uraltermo.ru/sortament/instrumentalnye-stali/

Tool steel grades

The issue of increasing the processing efficiency of structural steels remains always relevant. Research in this direction at one time led to the emergence of new grades of steel alloys intended exclusively for the manufacture of tools and accessories for them. They received the appropriate name - tool steels and alloys. What distinguished them from ordinary structural ones? What properties did they have?

General information

Steel, the percentage of carbon in which is more than 0.7%, is called tool steel. The phase structure is based on martensite and only in some cases ladyburite.

It is used mainly in mechanical engineering as a material for the production of tools for processing ferrous and non-ferrous alloys.

Tool steel has a number of features compared to structural steel. Among them, the most important are:

Increased hardness, which is 60-65 units on the Rockwell scale.
Extra strength. The tensile strength should not be lower than 900 MPa.
Ability to resist abrasive wear.
High hardenability is the property of steels to be thermally hardened.
Red resistance, which characterizes a metal in terms of its ability to maintain its strength characteristics with increasing temperature exposure to it.

According to state standards, the following types of tool grades are provided, based on their technological purpose:

Tool carbon steels GOST 1435-99. Marked with the letter “U” at the beginning of the marking. The number that follows in the designation shows the carbon component: U12, U10, etc. The dimension is taken in hundredths of a percent. The letter “A” may be placed at the end (for example, U10A), which indicates that this tool steel has a reduced number of negative inclusions. In particular, this applies to sulfur and phosphorus, elements responsible for the deterioration of the mechanical properties of the steel alloy.
Alloyed tool steels GOST 5950-2000. The number at the beginning shows one hundredth of a percent of carbides in steel. If it is absent, the value of this parameter is assumed to be 1%. This is followed by the letter designation of alloying elements with numbers indicating their content in whole fractions of a percent: X, 5ХВГ, 9ХС and so on.
High-speed tool steels GOST 19265-73. In technical documentation they are marked with the letter “P”. The number behind it indicates the approximate content of tungsten, the basic chemical component for this steel. In addition to it, high-speed cutters can contain cobalt and vanadium. They are also indicated in the marking with the corresponding letters: K and F. Chromium in all high-speed steels ranges between 3-4%. For this reason, it is not indicated in the labeling.
Stamped tool steels GOST 1265-74. This type of steel is marked similarly to alloyed steel. Depending on the nature of their application, they can be cold- and hot-formed stamped steels.

Let us now consider each point in more detail.

Tool carbon steel

This class in mechanical engineering is used as a material for the production of cutting tools with a minimum overall size of no more than 13 mm. The reason for this limitation lies in their limited hardenability. Larger overall dimensions are only possible if most of the cutting edge is on the surface (short drills, countersinks, etc.).

For most cutting tools - countersinks, hacksaws and cutters - U13, U11 and U10 steels are used. If the steel alloy operates under conditions of strong impact, it is recommended to use grades of type U8 and U7. They have a high impact strength coefficient and, accordingly, are able to withstand large dynamic loads.

The advantages of tool steels of this class are low price, acceptable cutability in the annealed state and moderate hardness. To improve their mechanical properties, various types of heat treatment are used. First of all, this is quenching in a saline solution or water at 820 ºС plus low tempering, the main purpose of which is to relieve internal stresses.

The main disadvantage of carbon tool steel is the narrow range of hardening temperatures, which increases the internal deformation of the steel during heat treatment. For this reason, the use of these alloys is limited to tools operating at low cutting speeds and heating temperatures up to 220 ºС.

Alloy tool steel

Compared to the one described above, the alloyed one has a greater thickness of the hardened layer and a lesser tendency to overheat, which can significantly reduce the risk of cracking during heat treatment of the tool. Thanks to this, the minimum overall size of the tool increases from 12 to 40 mm.

Low-alloy steel grades 11X and 13X are recommended for the manufacture of taps, knives and files with a thickness of 1-15 mm. Especially if the specified tool is long.

Steels 9ХС and ХВГС have increased red resistance with a critical temperature of 250 ºС. They are used for drills, dies, dies and other tools with a diameter of up to 80 mm. Their disadvantage is their slight fragility in the annealed state and sensitivity to cracking during grinding.

Also, alloy tool steel has proven itself excellent in the manufacture of various types of measuring instruments - calipers, rulers, staples, etc. - due to the low value of the coefficient of thermal expansion. The most suitable of them were steel types X and XG.

High speed tool steel

High-speed tool steels are distinguished from all the types of tool steel alloys presented above by their higher red resistance. These alloys do not change their mechanical characteristics at temperatures up to 650 ºС. As a result, cutting speed increases by 5 times, and tool life increases by 32 times.

This became possible due to the inclusion of tungsten or its analogue of molybdenum in their chemical composition. Also, the addition of metals such as cobalt, vanadium and chromium to steel has a positive effect on heat resistance. The most popular brands in the mechanical and machine tool industry are R18, R12, R6M4 and R10K5F5. Of this group of tool steels, it is worth noting P12, because it has better manufacturability: it is more amenable to pressure treatment.

Thermal treatment of these steel alloys includes hardening at 1250 ºС and repeated low tempering at 350 ºС. Exceeding the specified temperatures is extremely undesirable, because this leads to a sharp decrease in mechanical characteristics, in particular the formation of brittleness. Sometimes, to improve the corrosion-resistant properties, high-speed cutters are additionally treated with steam.

Stamped steel

Stamped tool steel is used in the production of dies and punches. As mentioned earlier, it is divided into cold and hot deformed steel.

Cold-formed tool steel operates at a temperature of 250-300 ºС. These include X12M and X12F1, which are based on the ladyburite phase structure. Their difference is the high value of hardenability, red-hardness and hardness (64 HRC). They are used to make massive dies of complex shapes, rollers for thread rolling, etc.

Hot stamped steels work with hotter metal, the temperature of which can reach up to 550 ºC. Therefore, among other things, they must have heat resistance - the ability to withstand repeated overheating without cracking. The most popular brands here are 5ХНМ and ХГМ.

Tool steels at one time made a technological breakthrough in the field of metal processing. Their use made it possible to increase the cutting speed by almost 5 times. But progress does not stand still. Now they are becoming less and less relevant. Especially against the backdrop of news about the improvement of ceramic alloys.

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

Properties and composition of carbon steel, application and labeling

The scope of carbon steel is wide - it is used to create tools, load-bearing structures and elements for mechanical engineering are made from it. Currently, this is one of the most popular types of steel, as it has unique properties. Its operational and technical properties are determined by the components and their ratio in the composition.

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Compound

Carbon and additional elements are used to melt steel. Depending on the future purpose, certain requirements are imposed on the material: hardness, ductility, fluidity, etc. These parameters can be adjusted by changing the % carbon content.

Its ratio to the total volume is one of the main conditions for dividing steel into types.

Their distinctive qualities and features are described in regulatory documents:

Ordinary quality - GOST 380-85.
Structural – GOST 380-88.
Instrumental - GOST 1435-54 and GOST 5952-51.

carbon determines the hardness index. The more it is, the different the product will be. However, it must be taken into account that at the same time fragility increases.

Depending on this indicator, steel is divided into several types:

Low carbon – up to 0.25%. It has good ductility and is relatively easy to deform, both in a cold state (suitable for cold forging) and under the influence of high temperatures.
Medium carbon – from 0.3% to 0.6%. It has sufficient strength, but also has good ductility and fluidity, which is important for processing. Scope of application – structural elements whose operation implies normal conditions.
High carbon - from 0.6% to 1.4%. High-strength tools and measuring instruments are made from it.

Each of these types of steel has a specific area of application.

Ordinary quality

This is the most popular type of steel at present. It is produced in the form of rolled products - sheets, rods, channels and beams. Due to its properties, it can be used as supporting structures and mechanical engineering elements.

In order to find out the properties of a certain type of carbon steel of ordinary quality. you need to know the principle of its marking.

The designation must always comply with GOST. The name indicates the type of metal - ST. Then comes a digital number that determines the perlite and carbon content. The higher the number, the stronger the product. The numbering can vary from 0 to 6. Then the name indicates the method of deoxidation - SP - calm; PS – semi-quiet; KP – boiling.

In addition, carbon steel is divided into three subtypes.

A – its chemical composition is not regulated. The main indicator is mechanical properties. It does not undergo a preliminary stage of pressure treatment. Not intended for welding.
B – its chemical composition must comply with regulatory documentation. Products made from this material can be processed - stamping, forging, etc. However, it is possible to change the mechanical properties. Some varieties can be exposed to heat.
And - the highest quality type of material. These brands are characterized by the mechanical properties of group “A” and the guaranteed chemical composition of group “B”. The structures can be welded together.

Group “A” is not indicated in the labeling. If the material grade corresponds to groups “B” or “C”, these letters are indicated at the beginning of the marking. When using manganese with a high content in the composition, the letter “G” is used in the brand name. Example: BSt3Gps – steel of group “B”, with a carbon content corresponding to the designation “6”, with the addition of manganese in a semi-quiet state.

High quality

In the manufacture of these types of steel, increased demands are placed on both the chemical composition and mechanical properties. In addition, the content of harmful components is regulated.

Sulfur – no more than 0.04%.
Phosphorus – no more than 0.035%.

These varieties are designated by the letter “U”. The numbers following it indicate the % carbon content (in hundredths of a percent). Such steel grades are used for the manufacture of tools, critical elements in mechanical engineering, as well as in the production of precision measuring instruments.

U7 – used for the production of chisels, dies, forging tools, and hammers.
U8 and U8G (containing manganese) – punches, metal knives, tools designed for stone processing.
U9 – tools for woodworking, punches, stamps.
U10 and U11 – taps, reamers, dies, blades for hacksaws.
U12 and U13 – cutters for processing hard metal, drills.

What else should you pay attention to when choosing carbon steel? It is important to remember that the better the hardness index, the more fragile the product will be. Thus, high-quality tool steels are characterized by good mechanical strength, low fluidity and ductility.

Source: https://ismith.ru/metal/uglerodistaya-stal/

Spheres and areas of application of steel. Where is steel used?

Metals have always occupied an important place in human activity. They are used to produce all kinds of parts and mechanisms for various industries.

In this article we will talk about such an important metal as steel. Surely many have heard about it, but not everyone knows what areas and applications of steel. We will talk about this and much more today.

What is steel?

Steel is an alloy of iron and carbon, the amount of which does not exceed 2%. The higher the carbon content, the harder the steel is, but less ductile. Various metallic and non-metallic substances are also added to the alloy - sulfur, phosphorus, silicon, and various metals. The amount and type of impurities affect the composition of steel and shape its appearance. Let's look at the main types of steel.

What types of steel are there?

According to standards, steel is divided depending on its quality into special quality steel, structural steel and tool steel. Steel can also be carbon or alloy. Depending on how much carbon the alloy contains, low-carbon, medium-carbon and high-carbon alloys are distinguished. The amount of carbon in such alloys varies from 0.25% to 2%.

Alloy steel means that a certain amount of some metal has been added to the alloy, thereby giving the steel special properties (corrosion resistance, frost resistance, impact resistance). Such steel can be low-, medium-, or high-alloyed (the content of alloying substances ranges from 4 to 11%).

Application of carbon steel

It is worth noting that a certain type and grade of steel has its own area of application. Thus, carbon tool steel of high and increased strength of various grades is used for the production of metalworking chisels, hammers, screwdrivers, scythes, carpentry tools, saws, scissors, chipper knives, and wood turning tools.

Various products are made from low-carbon steels using cold stamping, as well as for small parts (lightly loaded toothed wheels, pushers). Medium-carbon steels are also used for the manufacture of small-sized parts - gears, connecting rods, flywheels. Steels with the highest carbon content - high carbon - are used to produce springs of various sizes and different types of springs.

Drills, forging tools, cutters, as well as tools for working stone and wood are produced from high-quality carbon steel grades U7, U8G, U9, U12 and U13.

Application of alloy steel

Steel with different alloys has more varied properties than ordinary steel. Alloy steel can be more brittle, more ductile or harder, it all depends on its composition. The purpose of such steel depends on what additives were added to the alloy.

Alloy steel is used in construction, mechanical and instrument making, and even in medicine. Let's look at the areas and applications of steel with alloy additives in more detail:

— production of surgical equipment;

— production of various pipes (seamless, electric-welded, hot-deformed seamless, straight-seam, spiral-seam);

— construction of bridges and roads for various purposes;

— shipbuilding and aircraft construction;

— production of drills, cutters, collectors, taps, dies;

— production of large parts of complex shapes;

— production of parts that are designed to work under conditions of friction and increased loads;

— production of knives for various purposes;

— creation of pipelines made of stainless steel (increased chromium content in the alloy).

Steel is a difficult metal. It has a complex classification and marking, but despite this, steel is irreplaceable and necessary for the normal functioning of various areas of industry and the national economy, and even medicine.

Source: https://naruservice.com/articles/oblasti-primeneniya-stali

Tool steels for cutting tools

According to their purpose, tool steels are divided into steels for cutting, stamping and measuring tools. In addition, carbide alloys are widely used for the manufacture of cutting tools, especially for high-speed processing.

Steels for cutting tools

1. Requirements for steels

The cutting tool operates under conditions of prolonged contact and friction with the metal being processed. During operation, the configuration and properties of the cutting edge must remain unchanged. The material for the manufacture of cutting tools must have high hardness (IKS 60-62) and wear resistance, i.e., the ability to maintain the cutting properties of the edge for a long time under friction conditions.

The greater the hardness of the processed materials, the thicker the chips and the higher the cutting speed, the greater the energy spent on the cutting process. Mechanical energy turns into thermal energy. The generated heat heats the cutter, the workpiece, and the chips and is partially dissipated.

Therefore, the main requirement for tool materials is high heat resistance, i.e. the ability to maintain hardness and cutting properties during prolonged heating during operation.

Based on heat resistance, there are three groups of tool steels for cutting tools: non-heat-resistant, semi-heat-resistant and heat-resistant.

When non-heat-resistant steels are heated to 200–300 °C during the cutting process, carbon is released from the hardening martensite and coagulation of cementite-type carbides begins. This leads to loss of hardness and wear resistance of the cutting tool.

Non-heat-resistant steels include carbon and low-alloy steels. Semi-heat-resistant steels, which include some medium-alloy steels, for example 9Kh5VF, retain hardness up to temperatures of 300-500 °C.

Heat-resistant steels retain their hardness and wear resistance when heated to temperatures of 600 °C.

Carbon and low-alloy steels have relatively low heat resistance and low hardenability, so they are used for easier working conditions at low cutting speeds.

High-speed steels, which have higher heat resistance and hardenability, are used for more severe working conditions. Carbide and ceramic materials allow even higher cutting speeds.

Of the existing materials, boron nitride, elbor, has the greatest heat resistance. Elbor allows the processing of high-hardness materials, such as hardened steel, at high speeds.

2. Carbon steels

Carbon tool steels are marked with the letter Y, and the number following it shows the carbon content in tenths of a percent. For the manufacture of tools, high-quality carbon steels of grades U7-U13 and high-quality steels of grades U7A-U13A are used. High-quality steels contain no more than 0.02% sulfur and phosphorus, high-quality steels - no more than 0.03%.

By purpose, carbon steels are distinguished for working under shock loads and for statically loaded tools. Steel grades U7-U9 are used for the manufacture of tools for working with shock loads, which require high cutting ability (chisels, metal stamps, woodworking tools, in particular saws , axes, etc.).

Steel grades U10-U13 are used for the manufacture of cutting tools that do not experience shocks or shocks during operation and have high hardness (files, scrapers, sharp surgical instruments, etc.). Simple cold-forming dies are sometimes also made from steel of these grades.

Carbon hypoeutectoid steels, after hot plastic processing (forging or rolling) and subsequent cooling in air, have a structure consisting of lamellar pearlite and a small amount of ferrite, and hypereutectoid steels have lamellar pearlite and excess cementite, which usually forms a continuous or discontinuous network along the boundaries of the former grains austenite.

Heat treatment of carbon tool steels consists of two operations: preliminary and final processing. Preliminary heat treatment of steels consists of annealing at 740-760 ° C, the purpose of which is to obtain a microstructure consisting of granular pearlite - pseudo-pearlite, since with such a microstructure after subsequent hardening the most uniform properties are obtained.

In addition, this structure facilitates the machining of the tool.

The final heat treatment consists of hardening and low tempering. Quenching is carried out in water from 780-810 °C, that is, at temperatures for hypoeutectoid steels lying slightly above LS3, and for hypereutectoid steels lying below Ast.

Carbon steels have a very high critical hardening rate - about 200-300 °C/s. Therefore, even the slightest slowdown in cooling during hardening is unacceptable, since this can lead to partial decomposition of austenite at temperatures in the pearlite range and, as a consequence, to the appearance of soft spots.

The decomposition of austenite occurs especially quickly in carbon steels at temperatures close to 500-550 ° C, where it begins almost instantly, proceeds extremely intensely and ends completely within a few seconds. Therefore, only tools of small diameter can be calcined through and through after quenching in water. However, at the same time, large internal stresses arise in them, which can cause significant deformations.

Tools that are large in size, when quenched in water and in aqueous solutions of salts, acids and alkalis, the cooling capacity of which is higher than water, are hardened to martensite only in a thin surface layer. The structure of the deep zones of the tools represents the products of austenite decomposition in the pearlite temperature range. The core of tools having this structure is less brittle compared to the martensitic structure.

Therefore, tools with such a core can withstand shocks and impacts better than tools hardened through martensite.

Carbon steels are most appropriately used for tools with a small cross-section (up to 5 mm), which can be quenched in oil and achieve through hardenability, as well as for tools with a diameter or minimum thickness of 18-25 mm, in which the cutting part is only on the surface layer, for example files, countersinks, taps.

Carbon tool steels are tempered at temperatures not exceeding 200 °C to avoid a decrease in hardness. The hardness of a finally heat-treated tool made of carbon steels usually lies in the HB.C range of 56–64. The advantages of carbon tool steels are low cost, good workability by pressure and cutting in the annealed state.

Their disadvantages are low cutting speeds, limited tool sizes due to low hardenability, and significant deformations after quenching in water.

3. Alloy steels

Low-alloy steels for cutting tools (13Х, 9ХС) also do not have high heat resistance and are usually suitable for working at temperatures no more than 200 - 250

Source: http://aliansmetall.ru/instrumentalnye-staly

Carbon tool steels

In mechanical engineering and other areas of industry, production activity consists of the production of blanks and parts that are obtained by mechanical processing.

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Modern materials can have very high levels of hardness and strength, which makes their processing more difficult.

In order to ensure fast and high-quality machining in the manufacture of cutting tools or their edges, carbon tool steels are used. Their peculiarity is their high resistance to mechanical stress.

Carbon tool steels

Such metals can also be used in the production of critical parts that are subject to high demands in terms of strength and hardness.

Main characteristics
Application
Classification
Marking

Main characteristics

Considering the main properties of tool steel, the following points should be noted:

Low sensitivity to overheating. During machining, the removal of a layer of material from the workpiece occurs due to the applied demand. Heating a metal leads to a change in its basic qualities. Therefore, high-quality carbon tool steels do not heat up even during prolonged friction with other surfaces.
Low sensitive to welding to workpieces. Due to the pressure exerted when feeding the tool at the time of processing the workpieces, the friction zone may heat up slightly, which causes an increase in the plasticity of some materials. If tool steel is welded to the surface, additional resistance will arise and the quality of the resulting part will significantly decrease.
In order to simplify the processing of metal, it is made more susceptible to processing by cutting.
Susceptibility to calcination is also determined by the specific chemical composition.
High ductility in a hot state makes it possible to obtain workpieces using the metal melting method.
High resistance to the decarburization process allows you to get the best results when carrying out hardening or other chemical-thermal treatment processes.
During processing, shock loading may occur, which in most cases causes the formation of cracks. High-quality carbon tool steel does not have this disadvantage.
Wear resistance and high strength, surface hardness.

Chemical composition of carbon tool steels

The chemical composition of carbon tool steels largely determines the basic performance qualities of the metal.

Application

The use of carbon tool steels largely depends on the chemical composition. Most often used to obtain:

Cutting tool. For many years, tools were made using ordinary steel, which could become hot during use and wear out quickly. At that time, lathe and drilling machines were installed, which could carry out processing only at low speed and low feed. The emergence of modern equipment, in particular CNC machines, has led to increased requirements for tools. Only the advent of tool steel and hard alloys made it possible to fully unlock the potential of modern equipment. Also, do not forget that in order to obtain high-quality surfaces, the feed rate must increase significantly; productivity can be increased by increasing the feed. Modern cutting tools can withstand repeated heating and cooling cycles, and their service life increases by several tens of times.
High quality parts. An example is the design of an internal combustion engine, which has surfaces with precise dimensions and roughness. To ensure that the moving elements do not change their shape during operation due to heating, they are made of tool steel.
Instruments used to make precise measurements. To obtain small parts with linear dimensional accuracy of several hundred millimeters, the workpiece should not be heated or deformed due to the pressure exerted by the cutting tool.
A casting mold that must withstand significant pressure.

Application of carbon tool steels depending on grade

For the manufacture of parts, the most suitable brand is U7 or U7A, for the manufacture of cutting and other tools, U10 or U12. This pattern is due to the fact that harder metals must be used to produce cutting tools.

The marking of carbon tool steels in this case indicates the percentage of carbon and the presence of other impurities.

The properties of carbon tool steel are largely determined by the carbon concentration - the higher it is, the harder the surface, but the brittleness also increases.

For cold pressing, grades U10 – U12 can be used. The tests carried out indicate that their hardness is 57-59 HRC. Among the features we note:

Sufficiently high viscosity.
High level of resistance to plastic type deformation.
Increased wear resistance.

If the dimensions of the tool are large, then alloys that contain useful impurities can be used.

It is customary to divide quality tool steels into 5 main groups:

Wear-resistant, heat-resistant and high-hardness - a group represented by high-speed alloy steel. In addition, this group includes alloys with a ledeburite structure, which is characterized by a high carbon concentration (more than 3%). The use of tool carbon steels of this group is in the manufacture of tools that can be exposed to high temperatures due to high cutting speeds.
Heat-resistant and tough steels are represented by an alloy that contains molybdenum, chromium and tungsten. The chemical composition of tool carbon steel of this group is characterized by a low carbon concentration.
Non-heat-resistant, ductile and high-hardness steels have a small amount of impurities and an average carbon value. This group is characterized by a low hardenability index.
Average heat resistance, high hardness, wear resistance are qualities characteristic of metals with 2-3% carbon and 5-12% chromium.
Low heat resistance and high hardness are characteristic of steels with a hypereutectoid structure. In most cases, they do not have alloying elements or their concentration is very low. The high level of hardness is ensured by the high concentration of carbon.

High-quality tool steel can be subjected to additional chemical-thermal treatment to change the composition and rearrange the crystal lattice, due to which unusual performance qualities are achieved.

Carbon tool steel products

Hardness is considered the main parameter, the high value of which does not allow the use of steel in the manufacture of tools or parts that are subject to shock or vibration during operation.

This recommendation is due to the fact that as the carbon concentration increases, the hardness increases, but the viscosity decreases.

A decrease in viscosity causes an increase in the fragility of the structure; as a result of the impact load, cracks and other defects may appear, and the surface may break off.

The classification by hardness level is as follows:

High viscosity and low hardness are characteristic of metals that contain no more than 0.4-0.7% carbon.
High wear resistance and hardness of the surface layer are achieved when the metal structure is saturated with carbon to 0.7-1.5%.

A higher carbon concentration makes the metal very brittle, which does not allow it to be used as a material in the manufacture of tools. In addition, alloying elements can increase toughness and reduce brittleness under conditions of high carbon concentration. In some cases, chemical treatment is carried out to provide a wear-resistant surface and a tough substrate, resulting in high performance of the tool or part.

Marking

Carbon tool steel grades can have both numbers and letters. In most cases, the marking of tool carbon steels at the very beginning has the letter “U”, which indicates the type of metal. The designation of carbon tool steel also has the following features:

The first numerical designation after the letter indicates in tenths the amount of carbon in relation to the entire composition.
There is also the letter “A” following the number indicating the concentration of carbon in the composition. It indicates that the carbon tool steel grade is of high quality.
The letter “P” can be used to designate the group of steel in question. In this case, this designation is followed by a letter that indicates the concentration of tungsten.
Other alloying substances are also indicated by the corresponding letter, followed by a number to indicate the concentration.
It is generally accepted that steel and the group under consideration necessarily contain chromium, but its concentration is not more than 4%. If a number is indicated after the corresponding letter designation, then the concentration of this substance is specified.

You can also find markings for tool carbon steels starting with a number. Let us give an example of the common alloys 9Х or 6ХГВ. The first number also indicates the concentration in the carbon composition, the following letters indicate alloying elements.

If a number is not indicated after the letter of the alloying element, then it is generally accepted that their concentration is 1%. In addition, the marking itself may begin with letter designations characteristic of the alloying elements - this indicates that the concentration.

Source: https://stankiexpert.ru/spravochnik/materialovedenie/uglerodistiye-instrumentalniye-stali.html

Products – Tekhmashholding – group of companies, official website

Carbon tool steels

Tool carbon steels contain more than 0.7% C and are characterized by high hardness and strength. These steels are divided into: - high-quality (GOST 1437-74): U7, U8, U9, U10, U11, U12, U13; - high-quality: U7A, U8A, U13A. The numbers in the grade indicate the average carbon content in tenths of a percent. Steels U7, U8, U9 have a fairly high viscosity and are used for tools exposed to impacts: carpentry, metalworking, forging tools, dies, punches, etc. Steels U10, U11, U12 are used for tools with high hardness on the working edges (HRC 62-64 ). These are files, saws, taps, cutters, gauges, etc. U13 steel is used for tools that require the highest hardness: scrapers, engraving tools. High-quality steels have the same purpose as high-quality ones, but due to their higher viscosity they are used for tools with a thin cutting edge.

Microstudy of carbon steel

Steels in the annealed state consist of ferrite, cementite, and pearlite. The structure of steel in the annealed state is determined by its carbon content and is characterized by the lower left part of the iron-cementite phase diagram. The microstructure of commercial iron (C < 0.025%) is ferrite with a small amount of tertiary cementite, which is usually located along the grain boundaries of the main phase (Fig. 7.2, a). The structure of hypoeutectoid steel (0.025 < C < 0.8%) after annealing is represented by ferrite and pearlite. The phases in the microscope field have different colors: ferrite is light, and pearlite is dark (Fig. 7.2, b). With an increase in carbon content in steel, the amount of pearlite phase will increase, while the strength and hardness of the steel increases, and ductility decreases, i.e. because pearlite contains a very hard cementite phase. The ratio of the areas of the structural components of hypoeutectoid steels determines the carbon content in them with sufficient accuracy (Table 5.1). Table 5.1

Chemical and phase composition of steels

Grade 20 40 60 80 carbon, % 0.2 0.4 0.6 0.8 Pearlite area, % 25 50 75 100 Ferrite area, % 75 50 25 0 The structure of eutectoid steel (C = 0.8%) after annealing consists entirely of pearlite , which, depending on the heat treatment, can be lamellar (Fig. 5.2, c) or granular. The hardness and tensile strength of eutectoid steel are higher than those of hypoeutectoid steel, and the ductility is lower. The structure of hypereutectoid steel (C > 0.8%) consists of pearlite and secondary cementite. Depending on the type of heat treatment, secondary cementite can be observed on a microsection in the form of light, small grains, or in the form of a light network along the boundaries of pearlite grains (Fig. 7.2, d). The amount of secondary cementite in the structure of hypereutectoid steel is small and increases with increasing carbon content in it. The presence of cementite in the structure of steel leads to a significant increase in its hardness and a decrease in ductility compared to eutectoid steel. The grain size of steel is one of the most important factors affecting its properties. Steels with fine grains usually have higher mechanical properties, especially ductility and toughness at ordinary temperatures. As the grain coarsens, the impact strength, hardness and other properties of steel decrease. The size of steel grains is characterized by the corresponding grain number of the standard GOST 5639 scale [6].

Source: https://pellete.ru/stal/gde-primenyayutsya-uglerodistye-instrumentalnye-stali.html

Carbon tool steel

Steel U7, U7A
Steel U8, U8A
Steel U9, U9A
Steel U10, U10A
Steel U12, U12A

Application area

Carbon tool steels are the cheapest steels in the category of tool steels (there are also alloyed, high-speed, die and roll tool steels) and do not contain specially introduced alloying elements.

In the manufacture of large-sized tools, an important characteristic is the hardenability of steels; according to this indicator, carbon tool steels belong to shallow hardenability steels. As a rule, their hardness after hardening is within HRC 63-66 and at the same time they have a soft core.

Carbon tool steels are used for the manufacture of tools that operate under conditions that do not cause heating of the working edge, operate at low processing speeds, and are not subject to heating during operation. Below is a list of tools that are manufactured using carbon tool steels:

side cutters
beards
smooth calibers
bits
countersinks
chisels
measuring instrument of simple form: smooth gauges, staples
woodworking tool
calibers of simple shape and lower accuracy classes
punches
cleavers
combination pliers
sledgehammers
metal cutting scissors blades
dies for cold stamping
small size machine taps
hand taps
hammers
needle files
knurling rollers
screwdrivers
rip saws and circular saws
saws for wood processing
dies for grains
small-sized reamers
rasps
fitter's assembly tool
chisels
axes
cutters

Tool steel. Steel grades:

Tool steel (IS) is usually called an alloy with high strength, wear resistance, hardness and low heat resistance, which contains more than 0.7% carbon (with the exception of die steels for hot deformation, in which carbon is 0.3–0.6 %).

Scope of application

Tool steel is used for the production of a variety of tools, hot and cold deformation dies, individual machine parts that are subject to increased wear even under moderate dynamic loads (gear wheels, roller and ball bearings, lead screws, etc.).

In order to improve the operational properties of the IC, it is subjected to special types of heat treatment (tempering, hardening). This makes it possible to increase the hardness of the IC to 60-66 HRC, and increase the bending strength to 2.5-3.5 H/sq. m.

Increasing the hardness index automatically increases the wear resistance of the material. Therefore, tool steel retains the original shape of its working surface and original dimensions, even when subjected to friction under high pressure.

Tool steel classification

IP is usually classified according to a number of parameters. For example:

By chemical composition:

Carbon.
Alloyed (low and high hardenability).
Tool roller.
Tool stamping.
High-alloy (high-speed).

Heat resistance:

With little stability.
With increased stability.
Stable (die steels).

Tool steel range

Tool steel is supplied to the consumer in the following assortment:

Square and circle hot rolled.
Stripe, square, forged circle.

All this can be made of alloy, carbon or high-speed steel. Square and circle made from MIS have increased machinability and are used for the manufacture of various tools.

High-strength steels after heat treatment are used for:

production of cutting tools (drills, cutters, saws, etc.);
production of equipment for subsequent processing of metals, carried out both in hot and cold conditions;
creation of molds, rolls, punches and upsetting matrices, hacksaws for metal and band saws, thread gauges, etc.;
processing into products produced by cold drawing.

Less hard steels are used for subsequent cold machining (milling, turning, etc.). The tool strip is primarily used for the manufacture of dies that allow metal to be processed by pressure.

Depending on the grade of steel from which it is made, the strip is divided into a couple of groups:

the first is used for the production of tools that are intended for cold processing of metals and other materials;
the second goes to the production of tools that allow metals to be processed by pressure at high temperatures (about 300 degrees).

Steel grades, marking of tool steels

Currently, there is no unified labeling system as such. In Russia, the Customs Union and the CIS countries, the marking system that was in effect in the USSR (alphanumeric) is used. The numbers indicate the percentage of certain chemical elements in the steel, and the letters indicate the names of these elements. The most common designations presented in the table below.

In the EU, marking is carried out according to the provisions of the EN 100 27 standard, consisting of two parts. According to the first, steels are given a name. According to the second, they are assigned serial numbers.

Name of the chemical element present	Letter designation
Chromium	X
Titanium	T
Tungsten	IN
Nickel	N
Copper	D
Manganese	G
Cobalt	TO
Silicon	WITH

Japanese markings are alphanumeric. Moreover, the letters indicate the group to which the specified material belongs, and the numbers indicate the properties of the steel and its sequential number.

In the USA, there are several designation systems in place (each standardization organization has its own), which is extremely inconvenient.

Carbon tool steel (ISU)

MIS is subdivided according to a number of indicators. For example, by:

chemical composition for:

high-quality (the percentage of phosphorus/sulfur is 0.035/0.03%);
high quality (the percentage of phosphorus/sulfur is 0.03/0.02%).

Purpose:

high-speed (indicated by the letter “P”);
electrical engineering (“E”);
ball bearing (“Ш”).

According to the method of further processing, etc.

The most widely used is MIS, which represents steel, the percentage of carbon in which is limited to 0.65-1.35. After its heat treatment (hardening of tool steel) is completed, the strength and hardness of this material increases significantly.

Currently, the trade offers 16 MIS brands, each of which has its own alphanumeric designation. The letters included in the ISU marking indicate:

U – carbon steel;
A – indicates that the alloy belongs to the high-quality group (always placed at the end of the marking);
G – the alloy has a high content of an element such as manganese;
the number placed after “U” shows the percentage (in tenths) of carbon content in the ISU.

Restrictions on the use of certain MIS brands

Of the 16 MIS brands currently produced by the industry, almost half have restrictions on their use. For example.

Tool steel grades U9A and U9. During the process of hardening, the grain sizes increase, which leads to an increased likelihood of warping of the metal and a change in its geometric dimensions. These grades have lower ductility and strength indicators than the following grades U10A and U10.
Steel grades U11 and U11A are used extremely rarely due to their specific properties.
ISU U13, U12, U12A, U13A have a maximum carbon content, which leads to a significant increase in the brittleness of steel of these grades after hardening. Therefore, it is not recommended to use them for making molds or dies.

Source: https://www.syl.ru/article/153556/new_instrumentalnaya-stal-marki-stali

Carbon tool steels: properties and applications

The characteristics that distinguish carbon tool steels make it possible to successfully use this material not only for the manufacture of tools for various purposes, but also for the production of casting molds, measuring devices, as well as other products for which increased demands are placed on the accuracy of geometric parameters.

The properties of carbon steels allow them to be used in the manufacture of molds for high-precision casting

Key Features

The modern metallurgical industry produces steel in significant volumes, since it is one of the main structural materials. The share of steels whose composition is enriched with alloyed elements is only 10% in this volume, the rest are structures and products made from conventional carbon alloys. This fact indicates that carbon steels can be called the main material used in modern industry.

Carbon steel products surround us everywhere

The widespread use of carbon steel is explained by:

low production cost;
good machinability by various methods (cutting, pressure, welding);
good performance data.

Tool steels, which belong to the alloys of the carbon group, are distinguished by a complex chemical composition, the basis of which (97–99.5%) is iron. In addition to the latter, they contain the following elements:

chromium, nickel and copper (they are added specially);
sulfur, phosphorus, nitrogen, oxygen, hydrogen (these elements are present in tool steel because they cannot be completely removed during its purification);
manganese and silicon (their appearance is determined by the peculiarities of the production of tool carbon steels).

main chemical elements in carbon steel

Carbon, which is deliberately introduced into their composition, has a significant impact on the characteristics of tool steels. The modification of the alloy structure depends on the amount of this element. Thus, tool steels, which contain less than eight tenths of a percent of carbon, have a pearlitic and ferritic internal structure, more than eight tenths of a percent have cementite and pearlitic, and exactly eight tenths of a percent have a completely pearlitic structure.

The large amount of carbon in the composition of carbon tool steels determines their following characteristics:

low ductility and good impact strength;
exceptionally high strength;
resistance to cold machining.

Hardness of metal products made from carbon steels

The characteristics of alloys that contain a significant amount of carbon are negatively affected by iron oxides. To reduce this influence, the following elements are specially introduced into the composition of carbon steels:

silicon (part of the volume of this element is converted into the form of silicate inclusions, the rest of it is completely dissolved in ferrite);
manganese (used to deoxidize an iron-carbon alloy, but at the same time solves other important problems: removing iron and sulfur compounds from ferrite and cementite that form the basis of the alloy, which have an extremely negative effect on its quality; increasing the strength of metal sheets obtained by hot-rolling technologies).

Permissible deviations in chemical composition in rolled products intended for further processing

Production methods

The most efficient and economical method for producing carbon tool steels, which has been used for many years, is oxygen-converter technology. It consists of blowing oxygen into the liquid cast iron poured into the converter. The duration of the production process using this technology does not exceed one hour. Carbon steels are also smelted in open-hearth and electric furnaces; Bessemer-type converters are used for this.

Carbon steel smelting

The production of tool carbon steels in Bessemer-type converters is characterized by high productivity, but has a number of significant disadvantages. When using this technology, it is not possible to remove all non-metallic impurities from the finished alloy.

Such steel contains a significant amount of nitrogen and other gaseous inclusions, which reduce its density and strength and lead to rapid aging of the metal.

In addition, the so-called Bessemer steels contain a lot of phosphorus and sulfur, which cannot be completely removed.

The oxygen-converter method allows you to remove phosphorus and sulfur or bring their content in the metal to an acceptable level. Steels produced using this technology are also characterized by a low content of nitrogen and other gaseous inclusions.

Melting tool carbon steels in open hearth furnaces allows one to obtain similar characteristics, but this technology has one big drawback - the duration of implementation.

To smelt steel in such a furnace, it will take approximately 11 hours, which negatively affects the economic feasibility of this process.

Technology that involves the use of arc or induction electric furnaces makes it possible to obtain the highest quality tool steel, which contains a minimum amount of phosphorus, sulfur and oxygen.

Compact Lego induction melting furnaces fit into small production spaces

This technology (the most expensive of all existing ones) makes it possible to obtain materials that are also intended for the manufacture of critical metal structures. Due to the high cost of this method, many metallurgical enterprises do not use it, preferring more economical technologies.

Classification

Carbon steels belonging to various categories are usually divided according to quality level into the following types:

metal of the highest quality, which contains no more than 0.03% sulfur and phosphorus;
high-quality steels, which are characterized by the following content of harmful impurities: phosphorus - no more than 0.035%, sulfur - no more than 0.04%;
steel of ordinary quality, which contains no more than 0.05% sulfur and no more than 0.04% phosphorus.

Steel alloys, which are classified as tool alloys, can only be of high quality and high quality. The requirements for structural steels are somewhat lower; this category may include alloys of ordinary quality and high-quality ones.

The quantitative carbon content of a steel alloy also influences which category it is classified into. Thus, steels with a carbon content not exceeding 0.25% are included in the low-carbon category, exactly 0.6% contain medium-carbon steels, and more than 0.6% are high-carbon steels.

Scheme of the microstructure of carbon steel depending on the carbon content (dark field - pearlite, light field - ferrite)

The type of structure of carbon steels may also differ. Depending on it, such alloys are divided into the following categories:

hypoeutectoid;
eutectoid;
hypereutectoid.

Application and labeling

Tool-type carbon steels include alloys in which the carbon content is in the range of 0.65–1.35%. Their chemical composition, as well as the characteristics that they must comply with, are stipulated by the provisions of GOST 1435-74 (as amended in 1999).

You can familiarize yourself with all GOST requirements for tool steels by downloading this document in pdf format from the link below.
GOST 1435-74 Unalloyed tool steel. Specifications Download

Application areas of tool carbon steels

The use of tool carbon steels is associated with the production of:

cutters, hacksaw blades, files, measuring tools (grades U11-U13A);
pneumatic type tools, chisels, different types of wire cutters, pliers, hammers (U7 and U7A);
taps, dies, reamers, drills, dies for cold stamping (U9-U10A);
punches, tools for countersinking, milling and wood processing, knives, dies (U8 and U8A).

By marking tool carbon steels, you can find out not only how much carbon is contained in their composition, but also about the quality category to which they belong. Thus, the designation U8A, for example, indicates that this alloy, which is of high quality, contains 0.8% carbon.

Examples of designation of rolled carbon steel

When using carbon tool steels, it should be borne in mind that products made from them are subject to mandatory annealing, hardening and subsequent tempering. These types of heat treatment, carried out at the appropriate temperature, make it possible to optimize the structure of such alloys and, accordingly, significantly improve their hardness and strength.

Source: http://met-all.org/stal/uglerodistye-instrumentalnye-stali-gost.html