Hardness of steels GOST 1050-2013. Comparison table.

Characteristics of steel grade 10

Steel 10 is a structural high-quality carbon steel, weldable without restrictions.
Welding is carried out without heating and without subsequent heat treatment, methods: manual arc welding, automatic submerged arc welding and gas protection, CTS, ESW. The plasticity of the metal allows them to be used for the manufacture of stamped parts and components. To produce industrial quantities of goods, cold stamping technology is used. Not prone to flake sensitivity, no tendency to temper brittleness. Hardness of steel 10: HB 10 -1 = 143 MPa. Cutting machinability In the hot-rolled state at HB 99-107 and σB = 450 MPa, Kυ hard alloy. = 2.1, Kυ b.st. = 1.6. It has found its application in the production of pipes and fasteners for boilers and pipelines of thermal power plants; pipe fasteners for nuclear power plants, fasteners for steam and gas turbines are made from steel 10. When using chemical-thermal treatment, the range of applications expands sharply; bushings, spring ears, diaphragms, washers, screws, parts operating up to 350 ° C are made from it, which are subject to the requirements of high surface hardness and wear resistance with low core strength. A high endurance limit determines the use of the material in the manufacture of critical parts that are designed for long-term operation. Forging is carried out at temperatures from 1300 to 700 0C, cooling in air.

General information about steel hardening technology

The main goals achieved by the hardening + tempering complex:

• increased hardness;
• increasing strength characteristics;
• reduction of ductility to an acceptable value;
• the possibility of using hollow products instead of solid ones, which allows reducing the weight of the metal product and the metal intensity of the production process.

Main stages of hardening:

• heating to temperatures at which the structural state of the metal changes;
• shutter speed set in the technological map;
• cooling at a rate that ensures the formation of a given crystal structure.

After hardening, tempering is carried out, which consists of heating the metal to temperatures below the line of phase transformations, with a further slow decrease in temperature. The result of heat treatment is influenced by:

• heating temperature;
• rate of temperature rise;
• holding period at quenching temperatures;
• cooling medium and rate of temperature decrease.

The key parameter is the heating temperature, on which the restructuring and formation of a new structural lattice depends. Based on the depth of action, hardening is divided into volumetric and surface. In mechanical engineering, volumetric hardening is usually used, after which the hardness of the surface and core differs slightly. Surface heat treatment is in demand for parts for which high surface hardness and a viscous core are important.

Decoding steel grade 10

Interpretation of steel: Structural high-quality carbon steels are produced in converters or in open-hearth furnaces. The designation of these steel grades begins with the word “Steel”. The next two numbers indicate the average carbon content in hundredths of a percent; numbers 10 indicate a content of about 0.1 percent.

What steels are hardened?

Not all steel grades can be hardened. Grades with a carbon content below 0.4% practically do not change hardness at quenching temperatures, so this method is not used for them. Hardening technology is most often used for tool steels.

Table of correct quenching and tempering conditions for certain types of tool steels

Mechanical properties steel 10

Chemical composition

The main characteristics of steel 10 are determined by its chemical composition. Structural alloys are characterized by a small number of alloying additives. One of the main components of steel, carbon, is contained in a small amount - 0.07-0.14%, which ensures sufficient hardness and good machinability of the metal.

The concentrations of useful technological additives are:

• silicon – 0.17-0.37%;
• manganese – 0.35-0.65%.

It is known that silicon and manganese are strong deoxidizers. Their combined influence provides:

• removal of dissolved oxygen from the metal during smelting;
• increasing the strength of the alloy without loss of ductility;
• reduction of red brittleness caused by the presence of sulfur.

In accordance with GOST 1050-88, steel 10 contains small amounts of other elements:

• chromium – up to 0.15%;
• nickel and copper – 0.3% each.

These elements add strength and corrosion resistance to the steel. However, their impurities are quantitatively insignificant, so the alloy cannot be classified as stainless.

Sulfur and phosphorus are difficult to remove impurities that enter the alloy from ore or cast iron. They worsen the quality characteristics of the metal, so they try to minimize their content. In this alloy they do not exceed 0.035-0.040%.

Mechanical properties of steel 10 at elevated temperatures

The study of relaxation resistance by the free bending method showed that samples subjected to MMTO have lower relaxation resistance at 150°C than in the initial state (after annealing). Additional annealing of samples after MMTO at 300-500°C allows for a sharp increase in the relaxation resistance of steels 10 and 35. The stress drop in samples over 3000 hours after additional annealing at 400°C for steel 10 and at 500°C for steel 35 decreases by 10- 30 times in comparison with samples after MMTO without additional annealing. In this case, the maximum relaxation resistance was obtained at slightly higher temperatures of additional annealing after MMHT than the maximum values ​​of the elastic limit.

The experimental data obtained suggest that the low relaxation resistance of the samples after MMTT is associated with insufficient stability of the fine structure of the metal. Additional pre-recrystallization annealing after MMTO makes it possible to more fully stabilize the structure and, thus, sharply increase the metal’s resistance to microplastic deformations under short-term and long-term loading.

Equipment for hardening

The equipment is divided into two main groups - heating units and cooling baths. At modern enterprises, the following are used to obtain quenching temperatures:

• thermal muffle furnaces;
• induction heating equipment;
• installations for heating in melts;
• laser heating devices;
• gas plasma devices.

The first three types of installations are in demand for volumetric hardening, the last three - for the surface process.

Quenching equipment is steel containers, graphite crucibles, furnaces that contain molten metals or salts. Quenching baths for liquid media are equipped with heating and cooling systems. Their design may include special mixers for mixing liquid media and eliminating the steam jacket.

Physical properties of steel 10

At a temperature of +20 0C, the density of steel is 7856 kg/m3

Scope of application 10HSND

The properties of this metal make it possible to use it for the assembly of metal structures that are planned to be used at both low and high temperatures. Products made from it can be used in a wide temperature range, from -70 °C to +700 °C.

Recently, the scope of application of this metal has expanded quite significantly. It is used in the following areas:

• building sector;
• production of road and construction equipment;
• manufacturing of mining equipment;
• forestry and agricultural machinery;
• mechanisms for processing construction and metal waste.

In the construction industry, this brand is used for the manufacture of various structures, including large ones (arches and spans of bridges, load-bearing elements of buildings).

For road and mining equipment, buckets and individual parts of excavator and bulldozer buckets are made from it.

This metal is widely used in the manufacture of various rippers and powerful hydraulic shears.

In agricultural engineering, this steel is used to produce plowshares and elements of squeezing presses. Logger grabs and bulldozer blades are produced for loggers. In the processing of building materials and metal waste, special knives are made for shredders, hydraulic shears, and linings.

Hardness of steel grade 10

Steel 10HSND structural chrome-silicon-nickel low-alloy

Steel 10HSND is a structural chromium-silicon-nickel low-alloy steel. Decoding steel indicates the following characteristics. The first two-digit number indicates the approximate carbon content, the letters indicate the presence of chemical elements, as indicated by the state standard, X - the presence of chromium, C - silicon, H - nickel and D - copper. A similar alloy is produced in the form of rolled sheets, angles, channels, strips, bars and pipes of various diameters.

Impact strength of steel 10

Foreign analogues of grade 10 steel