RU2341583C2 - Armoured steel - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: steel contains carbon, silicon, manganese, chrome, nickel, molybdenum, vanadium, aluminium, nitrogen, copper, niobium, sulphur, phosphor and iron, at following components ratio, wt %: carbon 0.29-0.38, silicon 0.15-0.37, manganese 0.30-0.60, chrome 1.20-2.00, nickel 1.20-2.20, molybdenum 0.72-0.90, vanadium 0.06-0.20, aluminium 0.01-0.05, nitrogen 0.005-0.020, copper is not more than 0.50, niobium is not more than 0.05, sulphur is not more than 0.012, phosphor is not more than 0.015, iron - the rest.

EFFECT: increasing of viscosity reserve, strengthening and plastic performance of steel, high shellproof endurance and armor survival.

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Description

The invention relates to ferrous metallurgy and can be used in the manufacture of parts of the armor of stationary objects and vehicle bodies exposed to armor-piercing shells of calibers 30-125 mm

Currently, for these parts, sheets and plates 30-160 mm thick are used from weldable and improved chromomolybdenum, chromium-nickel-molybdenum and chromium-nickel-molybdenum-vanadium steels containing up to 0.38 wt.% Carbon. The steels used for protivosnaryadnoy booking are hardened and high (500-650 ° C) tempering. Such heat treatment determines the high plasticity characteristics and the viscosity reserve of the material, ensuring survivability (lack of tendency to brittle fracture-splitting and rear spalling) of the armor parts. The level of strength characteristics (temporary tensile strength - σ _in ) is, as a rule, in the range of 850-1100 MPa. However, in connection with the improvement of means of destruction, the use of steels with a specified level of strength does not provide the necessary protection for armored objects in an acceptable thickness.

The main way to increase the service properties of armor parts is to create armor steels with higher strength characteristics while maintaining a sufficient level of ductility and toughness.

Known armor steel containing components in the following ratio, wt.%: Carbon 0.26-0.31; silicon 0.10-0.35; manganese 0.50-0.80; chrome 1.30-1.70; Nickel 0.50-1.00; molybdenum 0.30-0.50; sulfur and phosphorus not more than 0.015; iron the rest.

(“ARMOR PLATES FOR PROF OF PROJECTILE PURPOSES” Defense Standart 95-13 / 1, London, 1981, ANNEX A, p.6)

Armor plates and plates made of this steel have a tensile strength σ _in = 1100-1200 MPa with a thickness of not more than 36 mm. Thicker plates do not have an advantage in strength and, obviously, in armor resistance over currently used ones.

Known plate armor steel containing components in the following ratio, wt.%: Carbon 0.25-0.32; silicon 0.05-0.75; manganese 0.10-1.50; chromium 0.90-2.00; nickel 1.20-4.50; molybdenum 0.10-0.70; aluminum 0.01-0.08; boron 0.001-0.004; titanium up to 0.10; niobium to 0.050; vanadium to 0.10; nitrogen up to 0.012; sulfur not more than 0.005; phosphorus no more than 0.015; iron the rest.

(DE 4223895 C1, C22D 8/02, 1994)

Steel has a tensile strength of more than σ _in = 1350 MPa after quenching and low tempering in the temperature range 100-500 ° C. However, practice indicates low survivability characteristics of armored plates subjected to low tempering when interacting with armor-piercing shells at a ratio B / d≤1 of the thickness of the barrier B to the caliber of the projectile d.

The known composition and method of production of armored plates of steel containing components in the following ratio, wt.%: Carbon 0.15-0.20; silicon 0.10-0.50; manganese 0.70-1.70; chrome 0.50-1.00; nickel 1.00-2.50; molybdenum 0.20-0.70; aluminum up to 0.01; boron up to 0.005; vanadium 0.005-0.25; nitrogen up to 0.01; sulfur not more than 0.002; phosphorus not more than 0.02; iron the rest.

(EP 1052296 A2, C21D 9/42, 2000)

Known steel after hardening from a temperature of 940 ° C in water and tempering 320 ° C with air cooling plates has a thickness of 40-50 mm _{in the} tensile strength σ = 1345-1317 MPa. In this case, the tempering range recommended by the patent authors (150-550 ° C) will lead, as in the steel according to the patent (DE 4223895 C1, C22D 8/02, 1994), to reduced survivability of armor parts made of this known steel.

Known armored steel Swedish production ARMOX 370S, containing components in the following ratio, wt.%: Carbon up to 0.30; silicon 0.10-0.40; manganese up to 1.2; chrome up to 1.00; nickel up to 1.00; molybdenum to 0.70; boron up to 0.005; sulfur not more than 0.01; phosphorus no more than 0.03; iron the rest.

(Svenskt Stal, HEAVY PLATE DIVISION, ARMOX 370S, E77, Nov.1985)

A typical level of tensile strength of this steel after controlled quenching in rollers and tempering at temperatures above 400 ° C according to the manufacturer (Svenskt Stal OXELOSUND.) Is σ _in = 1200 MPa. However, from the analysis of the given dependence of hardness on the thickness of the plates, it follows that the indicated level of strength refers to sheets whose thickness does not exceed 50 mm.

Closest to the invention in the composition of the main alloying elements and the level of mechanical properties is steel XH654.

(Stal-Eisen Werkstoffblatt 1925.) Thyssen-Henrichshutte Lastenheft fur die Lieferung von Blechen des hochfesten Vergutungssonderstahles XH 654. Bericht Nr.Qb-Nr. 837/74)

The specified steel contains components in the following ratio, wt.%: Carbon 0.25-0.35; silicon 0.10-0.40; manganese 0.40-0.70; chrome 1.25-1.65; nickel 1.45-1.75; molybdenum 0.35-0.50; vanadium 0.05-0.15; sulfur up to 0.015; phosphorus up to 0.020; iron the rest. After thermal improvement, the strength of the sheet material reaches σ _in = 1380 MPa. However, with a plate thickness of 90 mm, the tensile strength drops to σ _in = 900-1100 MPa. The achieved level of strength properties cannot lead to a noticeable increase in ballistic resistance in a wide range of thicknesses of armor parts made of known steel.

The objective of the invention is the composition of the armored welded steel, providing at a satisfactory level of survivability a higher anti-shell resistance of the armor than the known armored steel.

The technical result of the invention is to increase the ballistic resistance and survivability of armor made of armored steel according to the invention.

The essence of the invention is armored steel containing carbon, silicon, manganese, chromium, nickel, molybdenum, vanadium, sulfur, phosphorus and iron, as well as aluminum, nitrogen, copper and niobium in the following ratio, wt.%: Carbon 0.29- 0.38; silicon 0.15-0.37; manganese 0.30-0.60; chrome 1.20-2.00; nickel 1.20-2.20; molybdenum 0.72-0.90; vanadium 0.06-0.20; aluminum 0.01-0.05; nitrogen 0.005-0.020; copper no more than 0.50; niobium not more than 0.05; sulfur not more than 0.012; phosphorus no more than 0.015, iron the rest.

The introduction of aluminum, nitrogen, niobium and copper into the composition of the armored steel according to the invention, as well as the claimed ratios of the main alloying components, contributes to the stability of obtaining high strength characteristics of the inventive armored steel and its welded joints. At the same time, armor steel has a sufficiently high level of ductility and viscosity reserve, as well as isotropy of sheet semi-finished products and plates, which ensures increased projectile resistance and survivability of armor parts and steel structures according to the invention.

The invention can be demonstrated by example.

Smelted 14 compositions of armored steel in an electric arc furnace (11 smelts of armored steel according to the invention and 3 smelts of steel of the closest analogue). From ingots of the specified heats were made electrodes subjected to electroslag remelting. Electroslag remelting of the electrodes was carried out in the molds to produce sheet ingots with a mass of ≈10 t, which were rolled on a 4500 mill on sheet semi-finished products with a thickness of 45 and 70 mm. Cards for shelling tests and samples for cutting out the type of fracture after their destruction by a static bending load were cut from the rolled metal. Cards and samples were quenched in water from a temperature of 910 ± 10 ° C and released at a temperature of 600 ° C, followed by cooling in water.

After testing the samples to determine the type of fracture, samples were cut from their material to determine the mechanical properties.

The chemical composition of the armored steel of various heats is given in table 1.

The results of determining the tensile strength of the material of the experimental rolled armored steels after heat treatment, which provides a satisfactory form of fracture of samples, for two groups of compositions of the declared steel with different carbon and prototype steel are shown in table 2.

Table 3 shows the results of determining the anti-shell resistance of plates with a thickness of 45 and 70 mm from the armored steel according to the invention and from the steel of the closest analogue. It should be noted that when testing cards 70 mm thick made of steel of the closest analogue, there were cases of brittle fractures in the form of splits and rear spalls with a diameter of 3 or more times the caliber of the armor-piercing core.

Considering the statistical nature of the determined values, the results given in Tables 2 and 3 are presented in the form of calculated statistical characteristics of the experimental samples of the ultimate strength (σ _in ) and the speed of the limit of conditioned lesions (V _PCP ).

At the same time, the actual level of tensile strength of the plate material after heat treatment, providing the necessary viscosity reserve, was 1272-1510 MPa for steel according to the invention and 1130-1306 MPa for steel of the closest analogue (see Table 2). The difference between the average values of tensile strengths for these steels is 138 and 197 MPa depending on the carbon content of the steel according to the invention and is statistically significant at a confidence level of 0.95.

The data presented in the tables allowed us to draw the following conclusions:

- armored steel according to the invention has increased strength with a sufficient level of ductility, stock of viscosity and isotropy of rolled billets;

- at different values of the ratio of the thickness of the armor to the caliber of the projectile, the average value V of the _{PCP of the} armored steel according to the invention exceeds the similar indicator of plates of known steel by 8-12% (this conclusion is statistically significant at a confidence level of more than 0.95);

- armor made of armored steel according to the invention has increased anti-ballistic resistance and survivability.

Table 1
The chemical composition of the experimental steel melts Steel Swimming trunks number The content of components, wt.% FROM Si Mn Cr Ni Mo V Al N Cu Nb S R according to the invention 814 0.29 0.29 0.44 1.70 1.80 0.74 0.12 0.010 0.006 0.21 - 0.008 0.011 940 0.34 0.23 0.50 1.84 2.02 0.84 0.14 0.015 0.017 0.29 - 0.002 0.011 961 0.34 0.35 0.55 1,62 1.94 0.75 0.08 0,030 0.014 0.17 - 0.008 0.015 202 0.33 0.29 0.45 1,69 1.93 0.72 0.09 0,035 0.013 0.13 - 0.007 0.011 623 0.29 0.35 0.49 1.84 2.05 0.87 0.10 0,020 0.008 0.24 - 0.008 0.012 375 0.31 0.26 0.30 2.00 2.20 0.78 0.12 0,030 0.010 0.19 0.01 0.005 0.014 264 0.30 0.15 0.44 1,50 1.91 0.72 0.13 0,020 0.005 0.18 0.05 0.007 0.013 698 0.37 0.22 0.32 1.30 1.70 0.82 0.13 0,040 0.018 0.09 - 0.007 0.009 573 0.38 0.31 0.52 1.51 1.81 0.85 0.20 0,020 0,020 0.12 - 0.004 0.007 039 0.35 0.35 0.35 1.23 1.75 0.70 0.17 0,025 0.009 0.11 - 0.009 0.011 574 0.37 0.28 0.56 1.48 1,67 0.80 0.15 0,020 0.015 0.12 - 0.012 0.007 analog 175 0.31 0.20 0.40 1.24 1.47 0.50 0.10 - - - - 0.004 0.009 140 0.34 0.25 0.70 1.30 1.35 0.45 0.06 - - - - 0.003 0.007 114 0.29 0.34 0.45 1,50 1.74 0.32 0.15 - - - - 0.007 0.010

table 2
The results of determining the tensile strength of steel plates Steel Carbon content, wt.% Tensile strength, σ _in , MPa Number of definitions Standard deviation S, MPa Minimum Maximum Average according to the invention 0.29-0.33 1272 1434 1361 34 45.1 according to the invention 0.34-0.38 1380 1510 1420 31 46.5 analog 0.29-0.34 1130 1306 1223 eighteen 42.0

Table 3
The results of determining the ballistic resistance V _PKP Nominal thickness of plates, mm Meeting angle, degree Projectile caliber, mm Steel Values V _pkp , m / s Number of card tests, pcs. Standard deviation S, m / s Min. Maksim. Average 45 45 57 analog 645 735 675 6 22.0 according to the invention 661 743 700 eleven 25.7 70 0 one hundred analog 476 515 498 8 13.8 according to the invention 506 564 532 21 16.5 70 70 125 analog 1285 1328 1302 8 16,0 according to the invention 1328 1411 1370 8 26.2

Claims (1)

Armor steel containing carbon, silicon, manganese, chromium, nickel, molybdenum, vanadium, sulfur, phosphorus and iron, characterized in that it additionally contains aluminum, nitrogen, copper and niobium in the following ratio, wt.%: carbon 0.29-0.38 silicon 0.15-0.37 manganese 0.30-0.60 chromium 1.20-2.00 nickel 1.20-2.20 molybdenum 0.72-0.90 vanadium 0.06-0.20 aluminum 0.01-0.05 nitrogen 0.005-0.020 copper no more than 0.50 niobium no more than 0,05 sulfur no more than 0,012 phosphorus no more than 0.015 iron rest