RU2374354C1 - Composite steel for electromagnetic weapon - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention refers to metallurgy field, particularly to composite steel for manufacturing of electromagnetic weapon. Steel contains, wt %: carbon 0.04 - 0.12; silicon 0.10 - 0.60; manganese 5.0 - 12.0; chromium 19.0 - 21.0; nickel 4.0 - 9.0; molybdenum 0.5 - 1.5; calcium 0.005 - 0.010; niobium 0.03 - 0.30; nitrogen 0.40 - 0.70; silicon dioxide 2.0 - 10.0; aluminium oxide 3.0 - 15.0; iron and unavoidable impurities - the rest. Silicon dioxide and aluminium oxide are in the form of particles with nanodispersibility.

EFFECT: receiving of steel which is non-magnetic allows increased electrical resistance at simultaneous keeping of rates of plasticity, viscosity and electromagnetic permeability.

2 tbl, 2 ex

Description

The invention relates to the field of metallurgy and can be used in the manufacture of electromagnetic weapons.

Known non-magnetic steel of the following chemical composition, wt.%: Carbon 0,01-0,05; chrome 21.0-24.0; manganese 12.0-15.0; nickel 1.0-8.0; nitrogen 0.65-0.80; molybdenum 0.5-1.0; vanadium 0.25-1.0; calcium 0.0015-0.020; iron is the rest. (Aut. St. USSR No. 1225876, M.cl., C22C 38/58, publ. 04/23/1986.)

The disadvantage of steel is the insufficiently high plasticity and toughness characteristics and the development of intergranular corrosion due to the presence of vanadium in the steel, which, when combined with nitrogen and carbon, forms vanadium nitrides and carbides, which precipitate during solidification along the boundaries of austenitic grains. In addition, vanadium as a ferrite-forming element promotes the release of the ferromagnetic phase (δ - ferrite), increasing the magnetic permeability, which will reduce the efficiency of electromagnetic guns.

The closest in technical essence and the achieved result is a high-strength non-magnetic corrosion-resistant welded steel of the following chemical composition, wt.%: Carbon 0.04-0.9, silicon 0.10-0.60, manganese 5.0-12.0 , chromium 19.0-21.0, nickel 4.5-9.0, molybdenum 0.5-1.5, vanadium 0.10-0.55, calcium 0.005-0.010, niobium 0.03-0.30 , nitrogen 0.40-0.70, inevitable impurities and iron - the rest.

In this case, for the values of the concentration of alloying elements, the condition is satisfied:

([Ni] +0.1 [Mn] -0.01 [Mn] ² +18 [N] +30 [C]) / ([Cr] +1.5 [Mo] +0.48 [Si] + 2.3 [V] +1.75 [Nb]) = 0.70-0.90, where [N], [C], [Si], [Mn], [Ni], [Cr], [Mo ], [V], [Nb] - the concentration in the steel of nitrogen, carbon, silicon, manganese, nickel, chromium, molybdenum, vanadium and niobium, respectively, expressed in mass percent. The ratio of carbon to nitrogen is 0.05-0.15.

In addition, steel has a developed subgrain structure after hot plastic deformation at a temperature of 1000-1050 ° C with compression of 50-80% and subsequent cooling in water to room temperature.

Steel has a fine-grained austenitic structure after quenching in water at a temperature of 1030-1070 ° C. Steel does not have δ - ferrite and is practically non-magnetic subject to the indicated ratio of elements (RF Patent No. 2205889, Mcl C22C 38/58, publ. 06.10.2003, Prototype).

However, with vanadium in the steel at the upper limit, δ ferrite and a slight increase in the magnetic permeability of the steel may appear. The use of steel of this composition for the manufacture of electromagnetic weapons is undesirable. Another disadvantage of this steel is the usual electrical conductivity for a metal based on iron, which will increase electrical losses and reduce the efficiency of weapons.

The problem solved by the invention is to obtain high-strength non-magnetic steel with high electrical resistance.

This problem is solved in that the composite steel containing carbon, silicon, manganese, chromium, nickel, molybdenum, calcium, niobium, nitrogen, iron and inevitable impurities, additionally contains silicon dioxide and aluminum oxide in the following ratio of components, wt.%:

Carbon 0.04-0.12 Silicon 0.10-0.60 Manganese 5.0-12.0 Chromium 19.0-21.0 Nickel 4.0-9.0 Molybdenum 0.5-1.5 Niobium 0.03-0.30 Calcium 0.005-0.010 Nitrogen 0.4-0.9 Silica 2.0-10.0 Alumina 3.0-15.0 Iron and impurities rest,

wherein the steel contains silicon dioxide and aluminum oxide in the form of particles with nanoscale dispersion.

After hot plastic deformation at a temperature of 1150-1180 ° C with a compression of 50-70% followed by cooling in air, the composite steel has a fine-grained structure with uniformly distributed particles of silicon dioxide and alumina. After quenching in water from a temperature of 1050-1180 ° C, the steel has an austenitic structure.

The strongest solid-solution hardeners are penetration elements: carbon and, to an even greater extent, nitrogen. In addition, nitrogen, in comparison with carbon, provides the best combination of strength, ductility and toughness. When the carbon content is less than 0.04 wt.% And nitrogen less than 0.4 wt.%, The required strength of the matrix metal and ductility of the composite steel are not provided. When the carbon content is more than 0.12 wt.% And nitrogen is more than 0.9 wt.%, The processes of deformation aging begin to cause embrittlement of the metal. The content in the chromium matrix in the amount of 19.0-21.0 wt.% Not only provides corrosion resistance, but also the dissolution of the necessary nitrogen in the metal. When the chromium content is less than 19.0 wt.%, The nitrogen content in the steel of more than 0.40 wt.% Is not provided, and therefore, the required strength is not achieved with an increase in ductility and toughness, and the corrosion resistance of steel is reduced. With an increase in the chromium content of more than 21.0 wt.% And a decrease in nickel of less than 4.0 wt.%, The σ phase can precipitate and ferrite can form, which leads to the appearance of reduced ductility and cracks. An increase in nickel of more than 9.0 wt.% Reduces the solubility of nitrogen in steel. The manganese content in the range of 5.0-12.0 wt.% Together with chromium provides the solubility of nitrogen and, therefore, the content of its required amount in the steel matrix, which allows for a combination of ductility and toughness. Manganese, like nickel, stabilizes austenite with respect to the γ → α (M) transformation. A manganese content of less than 5.0 wt.%, As well as a decrease in chromium, does not provide nitrogen in steel more than 0.40 wt.%, An increase of more than 12.0 wt.% Leads to a decrease in the viscosity properties of steel due to the appearance of a large amount of nitrides as the γ → α transformation. Molybdenum, within the specified limits, as well as chromium and manganese, increases the solubility of nitrogen in iron, but with a content of more than 1.5 wt.% In the metal, a ferromagnetic δ-ferrite phase can form. When the molybdenum content in high alloy steel is less than 0.5 wt.%, It is not effective as an alloying element. Niobium binds nitrogen to strong nitrides, therefore, an increase of more than 0.3 wt.% Will reduce the content of dissolved nitrogen in the metal and, as a result, will reduce the strength of the matrix. The niobium content in the steel of less than 0.03 wt.% Is not effective. Calcium additives in an amount of 0.005-0.010 wt.%, Which is an element with pronounced horophilic properties, makes it difficult to isolate excess phases along grain boundaries, which greatly increases resistance to intergranular corrosion and helps to ensure ductility. When the calcium content is less than 0.005 wt.%, The horophilic effect is not observed, and an increase of more than 0.010 wt.% Contributes to the release of its excess along the grain boundaries and plasticity decreases due to embrittlement. The minimum silicon content is determined by the metal deoxidation processes, and the silicon content of more than 0.6 wt.% Reduces the solubility of carbon and nitrogen in austenite. Calculations of nickel and chromium equivalents in accordance with the Scheffler formula and diagram show that the metal matrix of the proposed composite steel is in the austenitic region, which ensures the production of non-ferromagnetic steel, in addition, with sufficient ductility and toughness.

The introduction of finely dispersed particles of silicon dioxide (SiO ₂ ) and aluminum oxide (Al ₂ O ₃ ) in the amount of from 5.0 to 25.0 wt.% Increases the electrical resistance of this steel, since silicon and aluminum oxides have a specific electrical resistance of 19- 20 orders of magnitude higher than the electrical resistivity of iron. The introduction of oxides in the form of nanosized particles will not only increase the electrical resistance of steel, but will also maintain the level of magnetic permeability, ductility and strength. When the content in the composite steel of silicon dioxide and aluminum oxide in the amount of less than 5.0 wt.% Increase in electrical resistance is not enough and the efficiency of the weapon will decrease. If the total content of silicon dioxide and aluminum oxide in the composite steel is more than 25.0 wt.%, The composite steel will have reduced plastic and viscous properties and the resistance of the barrel will decrease. The ratio of silicon dioxide and aluminum oxide in the composite steel was selected on the basis of their molecular weights and the fact that dissimilar particles during the operation of the product under the influence of thermomechanical cyclic stresses are less prone to coagulation and coalescence compared to homogeneous ones and thereby delay the softening of the material, while maintaining properties of electrical resistance of steel.

Thus, the technical result of the invention is to increase the electrical resistance of the material while maintaining ductility and viscosity and magnetic permeability.

Example 1

Composite steel was obtained by powder metallurgy methods. Powders of steel components: carbon, silicon, manganese, nitrided ferromanganese, chromium, nitrided ferrochrome, nickel, molybdenum, niobium, silicocalcium, iron was ground separately in an AGO-2 planetary mill, then mixed and mechanochemical alloying was carried out in a planetary mill.

Silicon dioxide and alumina were processed in a planetary mill of the AGO-2 type separately to particles of nanosized dispersion. The powders were mixed in proportions corresponding to the chemical composition of the proposed composite steel. The resulting mixture was subjected to cold and hot pressing at a temperature of 1150 ° C, and then hot extrusion at a temperature of 1180 ° C with a hood of 8 onto bars with a diameter of 15 mm on a press with a force of 400 tf. After heat treatment, samples were prepared from the obtained rods to study the properties of the metal.

Example 2

Composite steel was smelted in an open main induction furnace with a capacity of 100 kg by the method of fusion of stainless nitrogen-containing waste and pure ferroalloys. Nitrogen was introduced into the composition of steel with nitrided wastes and nitrided ferroalloys of chromium and manganese. Silicon dioxide and alumina were crushed in a planetary mill of the AGO-2 type separately to particles of nanosized dispersion, then they were packed in sealed cartridges and introduced onto a metal stream when melting was released into the ladle. The metal was poured into ingots weighing 100 kg and a diameter of 100 mm. During the smelting process and during the casting process, gaseous nitrogen was produced on the mirror and on the metal stream. The ingots were heated in a gas furnace to a temperature of 1150–1180 ° C and forged onto billets with a cross section of 50 × 50 mm, followed by hot rolling to 15 mm rods. After heat treatment, samples were prepared to study the properties of the metal.

The metal structure was studied using a Neofot-2 metallographic microscope. The phase composition of the steel was determined on a DRON-3M X-ray diffractometer. Studies of mechanical characteristics, including short-term and long-term strength tests at a temperature of 20-550 ° C, were carried out in accordance with the requirements of GOST 1497-80 (at 20 ° C) and GOST 9651-84 (at elevated temperatures) on a 1958-U10 testing machine . The resistivity was measured using the standard four-pin method.

The results of the chemical analysis of the proposed steel are shown in table 1. The test results are shown in table 2. As can be seen from tables 1, 2, options 1, 2, 3 are optimal. Option 4 showed that when the alumina content is less than 3.0 wt.% and silicon dioxide less than 2.0 wt.% reduced electrical resistance and deteriorate the magnetic permeability, strength, viscosity and ductility.

Option 5 showed that when the content of aluminum oxide is more than 15.0 wt.% And silicon dioxide more than 10.0 wt.%, The electrical resistance increases, but the magnetic permeability, strength, ductility and viscosity are deteriorating.

The test results show that the proposed composite steel, within the stated limits, is non-magnetic and has high electrical resistance while maintaining ductility and toughness.

Table 1
The chemical composition of steel Melting The content of elements, wt.% C Si Mn Cr Ni Mo Ca Nb N Al ₂ O ₃ SiO ₂ V Fe and impurities one 0.04 0.11 5,0 19.0 4.1 0.5 0.005 0,03 0.41 3.0 2.0 - Ost. 2 0.08 0.35 8.0 19.9 7.0 1,0 0.008 0.12 0.70 10.0 7.0 - Ost. 3 0.12 0.59 11.8 21.0 9.0 1,5 0.010 0.30 0.90 15.0 10.0 - Ost. four 0,07 0.21 9.0 20.5 5,0 0.6 0.009 0.05 0.50 2.9 1.9 - Ost. 5 0.09 0.41 10.5 19.8 8.0 1.3 0.008 0.25 0.80 15,2 10.1 - Ost. 6
prototype 0.4 0.26 11.7 20,0 5,6 1.4 0.008 0.24 0.60 - - 0.35 Ost.

table 2
Steel test results Melting ρ.ом.m σ ₁₀₀ , MPa 550 ° C σ _B , MPa σ _0.2 , MPa δ,% ψ,% KCU MJ / m ² µ, G / E one 1.4 × 10 ⁴ 810 1100 900 36 58 2.5 1.002 2 4,5 × 10 ⁴ 850 1120 950 35 56 2,3 1.001 3 9.8 × 10 ⁴ 900 1160 1000 33 56 2.2 1.001 four 4x10 ^-1 490 1060 870 31 54 2.0 1.004 5 9 × 10 ⁴ 800 1080 880 thirty fifty 1,1 1.004 6
prototype 9.8 × 10 ^-8 500 1050 850 32 55 2.2 1.005

Claims (1)

Composite steel for electromagnetic weapons containing carbon, silicon, manganese, chromium, nickel, molybdenum, calcium, niobium, nitrogen, iron and inevitable impurities, characterized in that it additionally contains silicon dioxide and aluminum oxide in the form of particles with nanoscale dispersion in the following the ratio of components, wt.%:
carbon 0.04-0.12 silicon 0.10-0.60 manganese 5.0-12.0 chromium 19.0-21.0 nickel 4.0-9.0 molybdenum 0.5-1.5 calcium 0.005-0.010 niobium 0.03-0.30 nitrogen 0.40-0.90 silica 2.0-10.0 alumina 3.0-15.0 iron and inevitable impurities rest.