Despite the rapid development of nanomaterials and new technologies, steel is still one of the main armor materials for the protection of land and naval military equipment.
Traditionally, armor plates are divided into anti-shell or thick-sheet (thickness 30-120 mm) and bulletproof or thin-sheet (thickness 2-25 mm).
In the USSR, the main production of thick-sheet armor steels was concentrated in Ukraine (Dnepropetrovsk, Zaporozhye and Mariupol), mainly high-strength electroslag remelting armor steels (ESP) of grades 22SH and 24SH were produced. In terms of their protective characteristics, these steels were not inferior, and even surpassed foreign analogues, such as KHN654 and KHN113 (Germany), Armox-270 (Sweden), Mars-240 (France). With the collapse of the Soviet Union, Russia had to transfer armored production to its territory and today the production of such armor is organized at the factories of Krasny Oktyabr (Volgograd), OMZ Spetstal (Moscow St. Petersburg) and MMK (Magnitogorsk).
As for new products, there are no significant developments in this area either in Russia or abroad, and the achieved strength level of 1000-1450 MPa and, accordingly, armor resistance is unlikely to change in the near future. However, the Russian consumer is not entirely satisfied with the current price of thick armor, which has increased significantly after the transfer of production to Russia. And since the share of costs for armor materials in the price structure, for example, of a tank, is 12-15%, then reducing their cost is a real way to reduce the price of the tank itself.
One of the obvious ways to reduce the price is to bring the characteristics of armor steels obtained by open smelting in oxygen converters to the characteristics of ESP steels. Open-cast armor steels are almost 2 times cheaper than ESP steels, but until recently it was not possible to ensure the required purity of these steels from harmful impurities, such as phosphorus, sulfur, etc., affecting armor characteristics. Today, this problem has been practically solved by the efforts of MMK, JSC Research Institute of Steel and UVZ.
Unlike thick steel armor, there is a real boom in the field of thin-sheet bulletproof steels today. Over the past 4-6 years, a whole family of ultra-high-strength bulletproof steels has been released to the market of armor materials. In Sweden, the family of ARMOX steels is filled with new brands of ARMOX-600 and ARMOX-Advance. In France, the new marks MARS-300 and MARS-600 have appeared and are being mass-produced, a line of bulletproof steels has been put into production in Germany, and even Finland has mastered the production of its own ultra-high-strength Steelramorimiilux. The strength level of these steels is 2000-2250MPa, the hardness is 550-640NV, the steels show good survivability, including at subzero temperatures.
Russia has also added to the list of its bulletproof steels. So now the ultra-high-strength steel of the 44C-Sv-Sh brand developed by the Research Institute of Steel, which has already received the letter O1 and is being entered into the documentation for promising samples of the military-industrial complex, is being adopted by the Ministry of Defense of the Russian Federation.
The main purpose of these steels is bulletproof booking of lightly armored vehicles. In the table.1. the characteristics of new bulletproof steels that have appeared on the foreign and domestic markets are given.
Table.1.New bulletproof armor steels for ViVT
The high strength of these steels is achieved primarily by increasing the carbon content. It reaches 0.47-0.50% in them already. The preservation of plastic characteristics is ensured by a combination of such technological alterations as vacuuming, electroslag remelting, controlled rolling and TMO.
As you can see, Russian bulletproof armor is at the level of the best global trends, although problems in Russia still remain and, first of all, they are associated with the lack of specialized armor production.
Aluminum armor is now widely used in the first line in lightly armored vehicles BMP, APC, BMD, etc.It is an ideal material for armored hull production, providing maximum rigidity of thin-armored structures. At the same time, it gives certain advantages in armor resistance in comparison with steel.
The pioneer of the use of aluminum, or rather aluminum-based alloys as armor, is the United States, where already in the late 50s the production of the M113 armored personnel carrier, which is still in service with NATO countries, was launched. Here, a conventional structural thermally reinforced alloy of medium strength was used as armor - the alloy SYSTEMALMGMN, according to the American classification alloy 5083, the closest analogue of which according to Russian standards is AMG5 alloy. This alloy can be classified as medium strength alloys and is characterized as weldable and corrosion resistant. The next stage in the development of aluminum armored hull production in the United States was the transition to the use of specially designed aluminum armor - a heat-resistant high-strength alloy of the ALZNMG system. He received the designation - alloy 7039. This aluminum armor was used for the armored hulls of the BMP M2 Bradley light tank M551sheridan.
In England, work on aluminum armored hull production led to the development of a light Scorpion tank and a whole family of vehicles based on it. The basis for the creation of the armored hull was a heat-strengthened alloy of its own design, alloy 7017 of the AlZnMg system. France, in turn, has developed its own aluminum armor alloy A-Z5-G. The AMX10R infantry fighting vehicle, which entered service with the French ground forces in 1973, was made of it.
The history of Russian (Soviet) aluminum armor for land military equipment began with aluminum armor components made of ACM alloy (medium-alloy heat-strengthened alloy of the VILS-Zn-Md system), included in the frontal projection of the BMP-1 and forming its upper-frontal, supermotor part. However, as in foreign countries, Russian developers quickly came to the need to create special armor alloys. Such alloys were developed in the early 70s (developed by the Steel Research Institute). They were named ABT-101 (alloy 1901) and ABT-102 (alloy 1903). These alloys became the basis for the development of BMD-1, BMD-2, BMD-3, BMP-3 and other vehicles based on them and are still the basis for the design of promising models of lightly armored vehicles.
If you compare Russian aluminum armor with foreign analogues, you can immediately notice the difference in approaches to the design of armored aluminum alloys, which is manifested not only in the metal aspect. Thus, foreign aluminum armor, as a rule, is developed in strict relation to its purpose, which is not available in Russia. This is one of the reasons that abroad, in particular, in the USA, today not 2-3 universal aluminum armor alloys are officially adopted and used, as in Russia, but dozens, and each has a strictly defined purpose and scope of application.
In the table.2 shows some of them, which are most often used in the armor protection of US military equipment in comparison with Russian alloys.
Table.2. Mechanical properties of foreign and Russian aluminum armor for lightly armored vehicles
In addition, unlike the West, Russian developers are increasingly using layered or so-called heterogeneous aluminum materials, i.e. materials whose front and back layers differ in chemical properties.composition and, accordingly, strength parameters. The front layer as the most durable provides maximum durability, and the back layer (less durable, but more viscous)- eliminates the split of the armor, i.e. ensures its survivability. And if in Western countries the layered aluminum armor has not come out of the experimental stage, then in Russia it has long been mass-produced and used along with the SABT-101 and ABT-102 as part of the same BMD and BMP. In addition to the well-known brands of layered aluminum armor, such as PAS-1 and PAS-2, today the Research Institute of Steel offers a wide range of their modifications, differing not only in chemical.the composition of the layers, but also their number. This makes it possible to increase the durability of layered aluminum armor materials by 7-15% in comparison with homogeneous ones.
Titanium armor has long attracted developers of protective equipment.This material gives a gain in comparison with steel or aluminum armor when fired with almost any small arms bullets and even with shell fire. This is due to the fact that titanium alloys are close to steel armor in strength, but they are almost 40% lighter.
At the end of the 60s, the Research Institute of Steel, together with VILS, VIAM, IMET named after A.Baykov and VSMPO, carried out work on the creation of a titanium tank body. The anti-shell titanium armor of this tank (alloy OT4-1) allowed to reduce the weight of the hull by 20-30% in comparison with the steel counterpart. However, the use of titanium both in Russia and abroad as armor has not been developed due to its high price. Titanium armor is almost 10 times more expensive than steel and costs almost the same as ceramic armor. In addition, until recently, high-strength titanium remained a very scarce material.
A few years ago, VSMPO AVISMA, with the participation of JSC Research Institute of Steel, developed and tested a new economically alloyed titanium alloy VST-2. This alloy is made using titanium waste (titanium sponge, chips, etc.), which makes it much cheaper than traditional high-strength titanium alloys of the VT6 type. At the same time, the mechanical properties of the alloy turned out to be very high, and the firing tests confirmed its unique armor characteristics. Today, this alloy is becoming competitive and is recommended for use, first of all, in means of individual armor protection (SIB), as well as for lightly armored vehicles, providing almost a 20% gain in weight compared to traditional steel armor when fired with armor-piercing bullets of 7.62-12.7 mm caliber.
A further increase in the ballistic characteristics of titanium armor is associated with the creation of heterogeneous structures. Today, developers are exploring technologies of HDPE or plasma surface treatment of titanium, which allow creating unique heterogeneous metal-ceramic structures that work perfectly against armor-piercing bullets of small arms.
Ceramics as an armor material was one of the first in the world to be used by the former Soviet Union.Moreover, ceramics began to be used both in armored vehicles and in military equipment. Already in 1968, ceramics in the form of corundum balls were used in the turret of the T-64 tank, providing a significant increase in anti-cumulative and anti-discharge protection. In the early 80s, the first 6B4 bulletproof vest with ceramic armor elements was used in Afghanistan. The ceramic armor based on boron carbide (B4C) created at that time is still at the level of the best world analogues in its characteristics. Recall that the use of ceramics allows you to reduce the weight of bulletproof protection by 30-45%.
The collapse of the SSS and the years of perestroika have thrown Russia far away from the leading positions, and currently it has to restore both scientific, technological, and production infrastructure in the field of ceramic armor in order to reach the world level. Today, Russian developers and manufacturers of armored ceramics have managed to bring its quality closer to the standards of advanced Western companies.However, they are not yet able to fully meet the needs of the Russian market in armored ceramics. Thus, according to the estimates of the Novosibirsk enterprise NEVZ-ceramics, the needs of Russian developers of protective armored ceramics amount to 2500-3000 tons per year, while all Russian manufacturers can supply the market with no more than 30-40% of its needs.
Currently, of the existing variety of ceramic materials, a very limited number of them are used for armor purposes: corundum or aluminum oxide (Al2O3), silicon carbide (SiC) and boron carbide (B4C). In the table.3 shows the main Russian manufacturers of armored ceramics. So far, the basis of Russian ceramic armor is corundum and silicon carbide. For comparison, in the USA only about 1,500 tons of ceramics made of boron carbide, one of the best armor ceramic materials, are produced for bulletproof vests.
Table.3. The main Russian manufacturers of electronic ceramics.
In the table.4 shows the comparative characteristics of ceramic armor materials and their relative cost in comparison with corundum.
The trends of the world market in the field of ceramic armor materials, which were determined in the early 2000s, continue to this day. For SIB, there is an expansion of the production of expensive, but most effective ceramics based on B4C, and for military equipment corundum or silicon carbide.
In addition to rigid metal and ceramic barriers, woven and non-woven polymer materials are increasingly used in protective equipment. Among them, the most famous are the Aramids.
Aramid was practically applied both abroad and in the USSR at the same time in the late 70s and early 80s. The era of these effective armor materials was opened by the famous Kevlar (USA) and the Soviet TSVM-J. Today, several dozen different brands of aramid fabrics have been created and used in the world, differing in the diameter of the initial fibers (microfilaments), the diameter of complex threads, the method of weaving, the price, etc. These materials have become an integral part of bulletproof vests, helmets, and are widely used as anti-shatter screens or substrates for ceramic armor panels.
At the end of the 90s, a new type of polymer fiber was created in the USA, the typical representative of which was the Nylon material. This material gave a gain in comparison with Kevlar in terms of durability, but as its operation in real conditions showed, it turned out to be resistant to ultraviolet radiation and other climatic factors and its protective characteristics rapidly decreased over time. Moreover, the reduction in armor properties reached 20-25%. For this reason, the above-mentioned class of materials in protective equipment has so far found limited use.
The next type of armored fibers were fibers from the phenylene class. A typical representative is the M5 fiber, which is currently used abroad in protective equipment primarily in bulletproof vests. This fiber has armor characteristics comparable to Nylon fiber, and in terms of resistance to climatic factors with aramids.
However, today, fibers based on high-molecular polyethylene are recognized as the most promising for ballistic protection by almost all developers of protective equipment.The materials of the group of high-molecular (high-modulus) polyethylene (highmoduluspolyethylene, HMPE), produced by the technology of pulling the thread from the gel, are widely used today both in everyday life and in the military field.
High molecular weight polyethylene (UHMWPE) is a fairly new material for Russia. It began to be used in SIB only 5-7 years ago, although it has been used abroad since the early 80s and more than a dozen brands of this material are currently known. Among them, the most well-known and widely used materials with the Dyneema trademark developed by the Dutch firm DSM and Spectra developed by the American company Honeywell.
Fiber bearing the Dyneema trademark was patented by the firm DSM in 1979. Ultra-high molecular weight polyethylene (UHMWPE) was used for its production. In the normal state, the molecules of this material are arranged in a chaotic manner. However, if these molecules are oriented in a given direction (along the fiber), then it is possible to obtain a fiber with unique strength characteristics. In the usual MMWPE, the orientation of the molecules is low, in the Dyneema fiber, the orientation of the molecules reaches 95% or higher. In terms of strength, the Dyneema fiber is 15 times stronger than steel and 40% stronger than aramids. In addition, UHMWPE is not afraid of water and is neutral to any aggressive environments. Its only drawback is that it loses its protective properties at high temperatures (over +70 °) and burns.
The technology of producing armor material from UHMWPE fibers is fundamentally different from the technology of producing aramid composites.
Aramid elementary fibers (microfilaments) are assembled into a complex thread. Then, a fabric is woven from a complex thread, where the threads intersect with each other. Depending on the type of weaving (twill, linen, etc.), these intersections are obtained with the appropriate density. Meanwhile, practice has established that any intersections of threads in an armored fiber composite negatively affects its armor properties. The developers of aramids, therefore, are trying to use technologies in which aramid fiber would receive minimal deformation both when producing complex threads and when weaving.
These problems were avoided in the production of armored composites made of UHMWPE fiber. The complex thread of them is not subjected to weaving. The threads are laid in one direction and, without intertwining, are connected to another layer, the threads of which are located in the other direction. Such materials are called unidirectional composites (UD materials).
Today, aramid materials of domestic production in their ballistic characteristics are not inferior to the best foreign analogues, although their price is significantly higher. But Russia still does not produce UHMWPE, and protection developers use only imported materials, mainly Chinese or Israeli production.
However, Rostec Group in 2015 announced a project to create production facilities for the production of UHMWPE at the Kazanorgsintez site with the production of at least 1200 tons of this fiber in 2017 and bringing its capacity to 4000 tons by 2020. At the end of 2016, a decree of the Government of the Russian Federation on the abolition of VAT for imported equipment necessary for the production of such polyethylene was prepared.However, while Russian developers of protective equipment continue to focus on imported materials and there is still a long way to complete import substitution.
Table 5 presents comparative data on the mass and price characteristics of protective structures made of polymer fiber materials.
It is clearly seen that ballistic packages from domestic aramids (columns 2-3), which provide protection from a standard fragment (a ball weighing 1g), in terms of mass characteristics approximately correspond to the same structures from UHMWPE, but are significantly (2-3 times) more expensive. It is also clear that domestic ballistic aramid fabrics, although better than Western analogues, are significantly more expensive.
If we do not take into account the exotic armor materials that are sometimes used in protection and materials for transparent armor, then, perhaps, the choice of armor protection developers ends with the materials discussed here. In any case, they are the basis for creating a variety of those protective structures that are used on existing military equipment and in the SIB. Naturally, these materials are used in various combinations, providing maximum protection against specified means of destruction with minimal mass and dimensional characteristics. In addition, increased security is achieved by the use of special protective complexes, such as dynamic protection, active protection, camouflage, etc.
The use of such complexes on armored vehicles was described in the magazine Arms Export No. 2 for 2016.
Authors: Alekseev M.O., Chistyakov E.N., Kuprunin D.G.
You can download the original article: ARMOR MATERIALS. THE CURRENT STATE.
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