Blog about sharpening. Excellent properties with proper heat treatment 40x13 steel decoding

Steel is alloy of several chemical elements. As a rule, it is created for specific purposes and with a narrow range of uses.

Steel 40×13 does not rust in all weather conditions, suitable for the manufacture of household appliances, knives and utensils. It does not contain harmful chemicals, which means it can be used safely in the food industry and industry.

Another plus is high heat resistance, as well as resistance to corrosive effects. The alloy acquires these features as a result of hardening due to a special manufacturing process. During this, the carbide is completely dissolved, which is why the substance does not enter into chemical reactions with others.

Characteristics

The convenience of using such a material is also due to the fact that the steel is made in an open-type furnace with a temperature regime of 850 to 1200 degrees, so the material is completely deformed and can be poured into completely different forms. The variability of the cooling and heating system allows you to create a product without defects, cracks and any irregularities.

Ingredients after hardening:

carbide particles
martensites,
residual austenites.

The latter element influences the stiffness of the resulting steel: the higher the hardening temperature, the lower the stiffness/hardness. That is why, if steel is required for knives (mild steel in knives is much easier and more convenient to sharpen), then the ideal hardening temperature will be 1050 degrees and above.

Application

Previously, this material was used for the manufacture of Soviet and inexpensive kitchen knives. Unfortunately, due to their low cost, they were of relatively poor quality (due to knife manufacturers, not steel), but they were perfect for ordinary household and kitchen purposes. With such a knife, it was easy to cut chicken and other meat dishes, but the most important plus is health safety. There is simply no risk of contracting any chemical disease using 40x13 steel.

A separate area of application is aircraft modeling. In aircraft construction, it is impossible for the material from which important components are made to be highly electrified and subjected to various corrosion, because human lives are at stake. Designers would not use low-quality steel, so this fact will be another plus. But the most common way of use is the manufacture of various component parts. High strength and the ability to use in wear mechanisms make the material main components.

It is worth noting that medical scalpels are made from the above alloy, which confirms the information about safety for the human body. Various technical devices are also produced from this steel: bearings, springs, elements for measuring systems, compressor parts and many things necessary in everyday life.

One of the main disadvantages is the fact that using this steel cannot be welded. With a sharp change in temperature, it loses many of its properties, begins to rust, and the crystal lattice is destroyed.

Any material, including steel, has certain properties that are unique to it. Specialists involved in the development of new steel grades make every effort to obtain optimal properties and characteristics. This fully applies to steel 40X13.

Main characteristics

Steel 40X13, sometimes referred to as 4X13, is classified as a corrosion-resistant, heat-resistant grade. Domestic substitute is steel 30X13. The chemical composition of this material includes:

carbon up to 0.45%;
chromium up to 14%;
other materials (silicon, manganese, etc.) up to 0.8%.

This composition makes it possible to manufacture the following products from this steel:

cutting and measuring tools;
medical, including surgical instruments;
structural elements operating in weak aggressive environments.
springs, fasteners, shafts and bearings capable of operating in aggressive environments, including at temperatures up to 450 ºC.

This material is obtained in open furnaces. Most often, induction furnaces are used. Steel melting is carried out at temperatures from 850 to 110 degrees Celsius. This mode ensures its complete deformation. To prevent the formation of cracks and other defects, various temperature regimes are used, applied alternately. By the way, for the use of parts from the brand 40X13 in aggressive environments, in order to increase its resistance to corrosion, it is recommended to grind their surface.

Steel of this grade must not be used to create structures using any type of welding.

Analogues

Among the imported analogues of steel grade 40x13 are the following:

USA - 420;
Germany - 1.4031;
PRC - 4S13.

GOST

The metallurgical industry produces the following assortment - sheet (GOST 5582-75), bar GOST 18907-73, wire (GOST 18143-72).

Heat treatment of steel

The 40X13 grade receives its unique properties, in particular, increased resistance to corrosion, as a result of complex heat treatment.

After hardening, the constituent components of steel 40X13 are:

carbides;
martensites;
austenite residues.

It should be noted that at a temperature of about 1050 ºC steel loses its hardness. This is primarily due to the fact that in this mode, the amount of austenite increases. But when the temperature drops to 500 ºC, hardness returns. This is due to the removal of carbides from the steel structure.

Finishing heat treatment (hardening) is carried out at a temperature of 950 - 1000 ºC, followed by cooling in oil or air. Subject to all technological regimes, steel to obtain the required hardness and corrosion resistance.

Technological properties of steel 40X13

Grade 40X13 has good manufacturability when plastic deformation is carried out in a hot state. It is carried out at a temperature of 850 to 1100 ºC. But we must remember that with sudden heating, steel can lose a number of its unique properties, for example, hardness. That is why the heating procedure must be carried out at a low speed. Upon reaching a temperature of 830 ºC, it is possible to perform rolling or forging. The cooling of the steel must also be carried out slowly.

Steel 40X13 is poorly exposed to cold deformation.

A number of characteristics of corrosion-resistant and carbon steel are similar in many respects, in particular, in hardness. But they have a different microstructure and this leads to certain difficulties in the process of machining.

The main difficulties that arise when turning and milling steel grade 40X13 are:

hardening arising in the cutting process;
disposal of processing waste;
accelerated wear of the cutting tool.

The fact is that when machining 40x13 cutting, the chips do not break like most carbon steels, but curl in the form of a long chip. To solve this problem, special devices are installed on the cutting tool - chip breakers.

Low thermal conductivity is good when using 40X13 in practice, but creates certain difficulties when turning. That is, at the place of processing, the temperature rises sharply, as a result of which hardening is formed and the surface is unevenly hardened. This property of steel leads to a decrease in the resource of the cutting tool and an increase in the processing of the part.

Another property of 40X13 is the presence in its composition of carbide and other compounds that have a microscopic size. Their presence makes steel a kind of abrasive that disables the cutting tool and this leads to a slowdown in processing.

For effective processing of stainless steel, a cutting tool is used, on the surface of which tungsten carbide and other hardening coatings are applied.

The use of steel 40X13

The unique properties of steel of this grade made it possible to use it in the aircraft industry. The fact is that this industry constantly needs materials that have high strength during operation at high temperatures, for example, in an aircraft engine. In addition, in modern aviation technology, parts made from this steel are used in load-bearing elements of the fuselage structure, etc.

Steel U8 belongs to the class of carbon eutectoid steels. In the initial state - after forging or rolling and cooling in air, its structure consists of pure lamellar perlite. Heat treatment of such steels is done in two steps: preliminary and final processing. The first consists in annealing for granular perlite at a temperature of 750-760 °C. Such a structure, firstly, facilitates machining, and secondly, after hardening, the properties will be more uniform. Feature of hardening of carbon steels, including U8, the inadmissibility of even the slightest slowdown during hardening due to the very high critical speed. Soft spots may form.

For steel U8 intermittent hardening is used. To implement it, the hot part is first placed in water, and then transferred to oil, where the final cooling takes place. Thus, it is possible to avoid the appearance of soft spots, but due to a decrease in the cooling rate at the last stage, structural stresses are reduced. Hardening of U8 steel is carried out at 780 ° C, and the tempering temperature is 400 ° C.

Guaranteed result subject to the parameters

Steel 40X13 well tolerates hot plastic deformation, which is carried out in the temperature range of 1100-860 °C.
Steel is prone to cracking when heated or cooled rapidly. Therefore, heating to 830 ° C is used slowly, and after deformation, cooling in sand or in a furnace.

After hot deformation, intermediate annealing is applied at temperatures from 740 to 800 ° C or complete annealing in the range from 810 to 880 ° C with slow cooling no more than 25-50 ° C / h to 600 ° C.

hardening 40X13 in the range from 950 to 1050 °C, it is used as a final heat treatment. Cooling - in air or in oil. Next, tempering is done taking into account the given hardness and corrosion resistance. For steel 40X13, used as a blank for surgical instruments, stepwise hardening is done from 1030-1040 ° C with cooling in an alkaline solution at 350 ° C. This is necessary to reduce warpage and increase elastic properties.

Special requirements are imposed on the heat treatment of 40X steel. The cooling time of parts made of this steel in water or in air or in water should be short due to its tendency to temper brittleness and cold brittleness. The presence of chromium reduces the critical hardening rate and prevents grain growth. Martensitic transformation temperature of steel 40X lower, its hardenability is higher than that of simple carbon steel 40. As a result, it is tempered at a higher temperature.
Steel 40X belongs to the improved group. Its performance is indeed improved as a result of proper thermal exposure. Thanks to him, the mechanical characteristics of steel are higher than that of a number of structural steels. While maintaining a sufficiently high toughness and ductility, this steel is one of the most durable.

Many masters think about how. First of all, we are talking, of course, about steel. Recently, the Russian market has been flooded with cheap Chinese products. Low-quality metal often looks beautiful, but is soft. In order for a metal tool to be usable, the steel must be hard. This problem is usually successfully solved by appropriate heat treatment - hardening.

Why is quenching and tempering necessary?

The main disadvantage of these methods is that they are unsuitable for home use. Nevertheless, situations often arise when steel products purchased from a specialized store need additional processing, namely strengthening. followed by leave is necessary because:

Most often, for the manufacture of products necessary in everyday life, metal of the AC40XM brand is used. For mechanical engineering, the 40HGM brand is most often used. For the manufacture of surgical instruments - metal grade 40x. Tempering metal at home, subject to all technologies, is no less effective than strengthening steel in production.

When working with metal, especially at high temperatures and in the presence of sources of open flame, safety precautions should be impeccably observed. This applies to both the worker in the steel shop and the home foreman.

Experts categorically do not recommend hardening steel using chemicals, as there is a risk of serious burns or severe poisoning. At home, it is best to use the thermal method of strengthening steel products, when metal molecules are more densely attracted to each other due to the active release of thermal energy. All work must be carried out outdoors or in a specially equipped room.

Main advantages

You can also harden metal yourself. The main thing is not to forget about the metal tempering, which must be carried out after hardening and temperature normalization. Sometimes this procedure is also called "annealing". The procedure for strengthening the metal with oil or the so-called "quenching in two environments" - in water and oil - is very popular. But a person who does not have experience should not undertake quenching using hot liquids, as serious injury can result from safety violations.

The absence of metal tempering after hardening often leads to the fact that, due to a sharp temperature drop, the metal becomes harder, but more brittle and brittle. If hardening takes place at the factory, the tempering procedure takes place in full accordance with GOST standards.

Here are the main advantages of hardening steel at home:

If a fire is used as a source of open fire, steel hardening should be carried out in calm weather so that an accidental gust of wind does not cause a fire. Be sure to protect your eyes with special glasses, as long-term observation of a bright flame can adversely affect vision. It is also necessary to wear overalls made of material that is resistant to fire.

How to make an ax stronger

To improve the quality of the metal from which the ax blade is made, you can easily harden it at home. Piercing and cutting products made of . Also, there should be no problems with metal products of the 40 × 13 brand. You can increase the hardness of the blade by simply lowering it into a fire. Experienced craftsmen easily determine the degree of hardening by the color of the ax lowered into it. Usually a product made of 40x steel first becomes bright red, and then the color gradually begins to fade. The color of a metal blade changes depending on the heating temperature approximately as follows:

Bright red color when the product is heated to 300 degrees;
Orange color at about 400 degrees;
Saturated yellow color when heated to 500-600 degrees;
Light yellow, almost white color at the final stage, when the incandescent temperature reaches about 750-800 degrees.

How to harden a steel knife

Heat treatment of steel knives, scissors or surgical instruments can be carried out in a muffle furnace. Such a furnace is well suited for small-sized products made of steel grade 40x. Some craftsmen also use a gas burner for this purpose, but this method is not safe, as a fire may occur.

The main advantage of the muffle furnace is that it can be used not only for quenching, but also for tempering. You can design this simple device for metal heat treatment with your own hands. Tempering steel at home in a muffle furnace is a safe way to increase the hardness of a metal without the use of chemicals (such as nitrogen). To harden a knife made of 40x steel, it must be placed in the oven while it is still warm.

Put the oven on the mode of gradual heating to the required temperature;
Cut sealing wax several times with a steel knife;
Do the same, but with a gradual decrease in temperature;
When the knife has cooled, carefully clean it of the remnants of the melted sealing wax.

This method is often used by surgeons to harden steel scalpels at home. Also, a muffle furnace is often used to strengthen metal parts used in the assembly and repair of cars and trucks.

Hardening metal is a great way to extend the life of a metal product. Of course, it is better to immediately purchase hardened parts and tools. But if this is not possible, you can easily increase the hardness of the material yourself. With certain skills and basic knowledge in the field of metallurgy, a good owner can easily cope with this important task. The main thing is to observe safety precautions and not to forget about such an important stage of hardening as tempering or annealing.

One of the most demanded materials in the field of human activity is steel. An alloy of iron and carbon has unique technical characteristics, thanks to which the versatility of this material is ensured. And among the best are the technical characteristics of steel 40x13, which is why it is used in a fairly large number of production processes.

Steel marking

In order to understand the characteristics inherent in the presented material, it is necessary to understand what its marking means. There are a large number of steels in the world, all differ in their properties. And every day a new brand of material can be produced. Therefore, you should understand the abbreviation of the product.

Steel 40x13 is alloyed, that is, in addition to carbon and iron, it contains other active elements. In this case, chromium is contained: this is indicated by the letter X in the marking. Its percentage is 1.3 percent. But the technical characteristics of steel 40x13 depend mainly on the amount of carbon contained in it. In this case, the material contains 0.40 percent of element with serial number 6.

Alloy steel production

Alloy steel production technology includes several stages, which are mainly performed in electric arc furnaces:

Purification of iron ore.
Steel smelting.
Introduction of additional additives.

First of all, iron ore is purified: foreign components, mainly sulfur and phosphorus, are removed. This process is carried out in open melting furnaces using out-of-furnace technology. The refining process is the removal of arsenic and non-ferrous metal impurities from the composition. It is carried out by means of vacuum melting.

The next stage in the manufacture of an alloyed steel grade consists directly in the smelting of a steel product. To do this, the raw material in an electric arc furnace is heated to a temperature of 400 to 600 degrees. During melting, iron turns into cast iron, which has an unstable crystal lattice. Through its stabilization, steel is obtained.

To do this, oxygen is supplied to the chamber, which, when burned, releases carbon into the atmosphere of the furnace. It, mixing with iron, converts cast iron into steel. After that, heterogeneous additives (in our case, chromium) are added to the raw materials. As a result, the crystal lattice of metal products becomes even more compacted, and an alloyed product is obtained.

Specifications

Following the smelting of the alloyed steel grade, the process of quenching and tempering the sample follows. Hardening of the sample is carried out at a temperature of 1100 degrees. After this, it is important to observe gradual tempering, otherwise the sample will be covered with cracks. To prevent this, this event is held at a temperature of 600 degrees.

Thanks to this manufacturing process, the final product has the following technical characteristics:

Temporary tensile strength - 1140 MPa.
The conditional yield strength at residual deformation is 910 MPa.
Relative elongation - 12.5 percent per five times the length of the sample.
Impact strength - 12 J /.

These characteristics allow the material to be used in various fields of human activity.

Application

In industry, steel 40x13 has been widely used. It is mainly used in environments with high humidity. The chromium contained in it enhances the anti-corrosion properties obtained from conventional hardening.

The presented brand has good plasticity indicators: at a temperature of more than 1000 degrees it is easily deformable. This material is actively used in the production of cutting and measuring tools, household items.

The characteristics of steel 40x13 made it possible to use it in the manufacture of machine parts, mainly bearings and compressor parts. The main condition for the use of finished elements is that the temperature of the working environment should not exceed 400 degrees. In construction, the material is practically not used, because it is not welded.

Anti-corrosion performance and their impact on the use of steel

Steel 40x13 GOST has distinctive indicators of corrosion resistance. It is achieved by hardening the product from a temperature at which complete dissolution of carbides is ensured. But, if the tempering temperature is increased after heat treatment, there will be a decrease in corrosion resistance due to the volatilization of chromium from the material. A decrease in parameters occurs at a release temperature above 600 degrees.

As a result, in order to obtain more favorable technical characteristics of steel 40x13, it must be tempered at temperatures from 200 to 300 degrees in order to obtain high hardness and corrosion resistance, or at a temperature of 600-650 units Celsius - to convert the product into structural steel .