EP1321535B1 - Material with high ballistic protection - Google Patents

Description

The invention relates to the use of a steel alloys as Material for ballistic protection bidding sheets.

A ballistic protective effect of objects, in particular of such laminar material is generally characterized by their safety against a breakdown of projectiles and splinters in high-energy Weapon action, with increasingly high protection and at the same time a reduced weight of the article or part with improved Economy of the provision are required.

It should be noted at the beginning of the accepted opinion that the usual mechanical measurement data from a tensile and notched impact test none direct implication regarding the properties of a ballistic material Allow stress. In many cases, however, the hardness, the impact resistance and the strength of the material used to provide at least an indication to create a penetration resistance of a protective part. At long last However, they identify the "holding shots" of a sheet metal part of it ballistic protective effect.

Is now approximately estimated that the strength, hardness and toughness can not change with the speed of the load, so can of it be assumed that the material of the protective parts both highest hardness than also has to have the greatest toughness to avoid ballistic destruction Exposure and a breaking effect on projectiles exercise. Now, for steels and alloys, these properties are in view opposed to their simultaneous maximization, so that next to one general improvement of the same a balance of toughness and Strength of the material, especially after a thermal annealing is claimed according to claim.

Depending on the desired property profile were for products with ballistic Protective effect carbon steels, low- and medium-alloyed steels, high-alloyed Steels and precipitation-hardenable alloys with optionally one Iron content of less than 55 wt .-% proposed and often a composite construction and / or a hard layer on the outer surface of the protective part as advantageous recognized.

For example, EP-A-180805 discloses a steel helmet from a low alloyed boron steel, wherein the steel helmet is sandblasted after tempering.

From EP-A-1052296 a tank sheet with compensation structure is known, which has a yield strength of> 1100 N / mm ² and a hardness of> 400 HB and at a carbon content in wt .-% of 0.15 to 0.2 im Substantially 1 to 2% by weight of chromium (Cr), 0.2 to 0.7% by weight of molybdenum (Mo), 1.0 to 2.5% by weight of nickel (Ni), 0.05 to 0 , 25% by weight of vanadium (V), balance iron (Fe).

FR-A-2106939 describes an armor consisting of two sheets. The one ballistic protective effect exhibiting sheet metal part in percent by weight 0.3-1% C; 0.5-1% Si; 0.1-1% Mn; 3-10% Cr; 0.5-3% Mo and 0.2-1% V up.

A process for producing thick armor plates is known from EP-A-580062 become known, in which above, increased in carbon and nickel content Alloy in slab form initially heated to a temperature of over 1150 ° C, increasingly allowed to cool and in the range of 1050 to 900 ° C, each with a high Forming degree is rolled to the final thickness.

In EP-B-731332 is a steel armor plate with improved penetration resistance described in relation to projectiles, which have a large number of inclusions in the Oriented substantially parallel to the plate surface and in a quarter to three Quarter of the plate thickness are concentrated.

An armor plate with a base material made of tough steel, on which through Clad at least one hard steel support facing the bombardment consisting of 0.6 to 1.0% by weight of carbon (C), 0.2 to 2.0% by weight of silicon (Si), 0.2 to 2.0 wt% manganese (Mn), 0.8 to 2.0 wt% chromium (Cr), 0.05 to 1.0 Wt .-% molybdenum (Mo), 0.05 to 0.35 wt .-% vanadium (V), balance iron (Fe) and Steel companion is applied, EP-B-247020 discloses. Between the Base material and the support is an intermediate layer of pure nickel or Pure iron with a thickness between 0.1 and 15% of the total sheet thickness arranged, which by roll cladding with the base material and the support connected is. The liner not only facilitates the plating of the Base material but also prevents chipping of the support material, although it can be quenched to a hardness of 55 to 60 HRC, but apparently has low toughness.

In addition to the above low and medium tempered steels were also high-alloy chrome steel alloys (CH-A-648354) and precipitation or martensite hardening steels (AT-336659, DE-C-19921961, EP-A-1008659) as Single or composite construction with optionally a hard outer layer proposed for ballistic protection. Such steels with high Alloy content up to 50% are indeed as a material for components with highly effective ballistic protection can be used advantageously, but have the Disadvantage of high costs.

Here the invention wants to create Abhillfe and sets itself the goal, materials indicate from which sheets with high ballistic protective effect low weight, economically produced in a simple manner. These Sheets are said to have a high projectile or flight-breaking effect possess, consist of an iron-based alloy, by a heat treatment or thermal compensation adjustable toughness and strength properties having both property characteristics maximized. Materials Technical are a composite production or a multi-layer part production and a Surface hardening possible and given a weldability.

This goal is achieved when using an alloy containing in wt .-%: Carbon (C) 0.26 to 0.79 Silicon (Si) 0.2 to 1.2 Manganese (Mn) 0.2 to 0.9 Chrome (Cr) 1.1 to 7.94 Molybdenum (Mo) 0.56 to 3.49 Vanadin (V) 0.26 to 1.74

Iron (Fe) and impurities as the remainder, with the proviso that the value for the content of phosphorus (P) plus sulfur (S) is less than 0.025,
P + S <0.025 wt%
the concentration of nickel (Ni) is below 0.28
Ni <0.28% by weight
and the sum of the grain boundary elements arsenic (As),
Antimony (Sb), bismuth (Bi), tin (Sn), zinc (Zn) and boron (B) is less than 0.011
As + Sb + Bi + Sn + Zn + B <0.011 wt%
as a material for the aforementioned sheets.

The advantages achieved by the invention according to the above characteristics are essentially to be seen in that by a restriction of the content of impurity elements sulfur (S) plus phosphorus (P) in combination to a value of less than 0.025 wt .-%, the prerequisite for Achieving high material toughness is achieved when it has been found that at the same time the other impurity components arsenic (As) plus antimony (Sb) plus bismuth (Bi) plus tin (Sn) plus zinc (Zn) plus boron (B) have a cumulative concentration is less than 0.011% by weight. Because nickel (Ni) surprisingly, in interaction with the other alloying elements, in particular with molybdenum (Mo) and vanadium (V), increases the risk of a combo occupancy, the nickel content is below 0.28% by weight. limited to the top. These inventively achieved advantageous properties of the material, which are markedly pronounced in a bombardment test by a high proportion of retained shots, become particularly clear on parts which have been tempered to a high strength of more than 1900 N / mm ² . It has also been shown that at sulfur contents of less than 0.005 wt .-%, a further improvement of the desired material properties is achieved.

In a selection in which one or more element (s) has the concentration (s) in% by weight: Carbon (C) 0.36 to 0.64, preferably 0.41 to 0.58 Silicon (Si) 0.36 to 0.9, preferably 0.41 to 0.68 Manganese (Mn) 0.36 to 0.7, preferably 0.41 to 0.59 Chrome (Cr) 1.7 to 5.95, preferably 2.61 to 5.2 Molybdenum (Mo) 1.05 to 2.9, preferably 1.3 to 2.7 Vanadin (V) 0.36 to 1.25, preferably 0.39 to 0.83 Superior results are achieved in the bombardment test. This is, as has been determined, justified by the fact that in close coordination with the other alloying elements, the respective concentration of (the) selected element (elements) positively influence the microstructural changes in the thermal annealing, that is, promote a hardness assumption without interference regions at the grain boundaries and When starting, ensure a largely homogenous compensation structure.

In addition to a high purity mentioned above or a low content of grain boundary effective elements of the material used in the invention acts It has also been recognized that the technology of manufacturing is ballistic Protective effect of parts made therefrom. The manufacturing technology Statements, as stated in claim 3, may individually and in Combination improving on the ballistic protection by such manufactured parts affect, because in particular the isotropy of the material is promoted. A remuneration can be improved to higher strength values Material toughness, whereby the product significantly increased Resistance to breakdown of projectiles learns.

If the material has the technical specifications that it has a strength of greater than 1800 N / mm, preferably greater than 2000 N / mm ² , in particular greater than 2100 N / mm ² , with a toughness at room temperature greater than SEP 150 J. , preferably greater than 185 J, in particular of about 245 J as measured by (S e teel isen rüfblatt P) in September 1314, has the highest breakdown products resistors and the like are the same strength achievable at low alloy cost.

Based on examples and of Fig. 1, the invention according to claims 1 to 4 be explained in more detail, wherein Fig. 1, the percentage of held shots in Depends on the thickness of the sheet metal.

Example 1:

An inventive sheet of an ESU block with a sheet thickness of 6.6 mm and a composition in wt .-% of 0.49 carbon (C), 0.59 silicon (Si), 0.3 manganese (Mn), 0.004 sulfur (S), 0.019 phosphorus (P), 3.23 chromium (Cr), 1.37 molybdenum (Mo), 0.29 vanadium (V) and 0.19 nickel (Ni), balance iron (Fe) and grain boundary active elements (arsenic (As), antimony (Sb), bismuth (Bi), tin (Sn), zinc (Zn), boron (B)) with a cumulative concentration of 0.008 was adjusted to a hardness of 56 ± 1 HRC tempered and subjected to a 100-round bombardment test, of which 93 Shot were held. Under the same bombardment conditions, one took place Testing a sheet of tempered carbon steel, which sheet 57 Shot stopped.

Example 2:

A sheet of Cr-Mo-V steel which has been ladle metallurgically treated and vacuum degassed, having a composition in wt% of 0.45 carbon (C), 0.62 silicon (Si), 0.64 manganese (Mn) , 0.016 phosphorus (P), 0.007 sulfur (S), 3.35 chromium (Cr), 1.62 molybdenum (Mo), 0.32 vanadium (V) was rolled from a slab block to a thickness of 7.5 mm. From the sheets samples were made, the same tempered and tested with different technologies. Table 1 shows the tempering parameters and the mechanical values achieved. Sample No. Härtetemp. start number rm Rp _0.2 A impact strength hardness ° C ° C N / mm ² N / mm ² % J MW HRC A 930 300 1 1941 1441 6.2 167 180 186 171 55 B 930 300 1 1872 1471 7.6 84 209 180 151 53 C 950 300 1 1975 1576 5.6 81 201 171 144 55

From the results, the effect is apparently different Compensation parameters on the mechanical properties of the material apparent, which clearly indicates a light adjustment according to the invention indicates the desired product data.

In comparison with tempered carbon steel of the same thickness were Bombardment test held by the sheet according to the invention by about 60% more shots.

In a further testing, a comparison of sheets of the invention was carried out with regard to carbon steel and martensite hardening steel held shots. Set the values indicated or drawn in FIG. 1 each mean of results from at least three shots.

In Fig. 1, the percentage of retained shots in dependence on Sheet thickness shown. From a plate thickness of 6 mm upwards is the same energetic conditions of shelling the proportion of shots held from a martensitic and hardening steel according to the invention manufactured sheet practically the same. The profitability is to determine that the material of the invention has an alloy content of about 6%, that of the martensitic hardening steel (comparative material) has 41.5% and thus has significantly higher costs.

The stated object is also achieved when using an alloy containing in% by weight: Carbon (C) 0.3 to 0.6 Silicon (Si) 0.08 to 0.59 Manganese (Mn) 0.1 to 0.6 Chrome (Cr) 0.9 to 1.5 Nickel (Ni) 2.4 to 5.5

Iron (Fe) and impurities as the remainder, with the proviso that the value for the content of phosphorus (P) plus sulfur (S) is less than 0.025, P + S <0.025 wt% the concentration of molybdenum (Mo) is less than 0.34 and that of tungsten (W) is less than 0.29, with the sum of molybdenum (Mo) plus tungsten (W) not exceeding two 0.38. Not a word <0.34 wt% W <0.29 wt% Mo + W / 2 <0.38 wt% and the sum of the grain boundary active elements arsenic (As), antimony (Sb), bismuth (Bi), tin (Sn), zinc (Zn) and boron (B) is less than 0.011
As + Sb + Bi + Sn + Zn + B <0.011 wt%
as a material for the initially mentioned sheets.

The obtained according to the invention with the immediately mentioned characteristics In essence, advantages are to be seen in the fact that on the one hand by the choice of the Alloy elements and their respective concentration by means of a Thermal compensation created desired high material strength is achievable. A high toughness of the material on the other hand, it has been found, thereby be achieved by three other alloying measures. By a Limitation of the sum content of sulfur (S) and phosphorus (Ph) upwards, which causes elements with respect to inclusion formation and embrittlement by being able to interact, is at least created the condition of high toughness of the material. The Elements Molybdenum (Mo) and tungsten (W) individually and in combination, which in themselves strengthening in alloys can be effective, but have the Tendency of embrittling grain boundary enrichment in the material, so that a above limitation of the content has a toughening effect. It It was also found that the grain boundary elements arsenic (As), antimony (Sb), bismuth (Bi), tin (Sn), zinc (Zn) and boron (B) already in small amounts Concentrations cause a steep drop in material toughness, if too abruptly effective high mechanical loads of the material, such as For example, comes at a bombardment of a part made of it, from what the determination according to the invention of the highest sum content results. As also mentioned at the beginning, those determined with material investigations mechanical material properties during high-energy weapon action change substantially, so that strictly speaking, just by a bullet test Penetration resistance of projectiles or splinters as well as a cracking behavior of protective parts can be assessed. According to the invention in the Claims characterized alloy as a material for sheets with high Ballistic protective effect not only the improved properties in this regard because of, but also for economic reasons special benefits because of Proportion of alloying elements in the steel below 8.8 wt .-%, a low distortion Thermal remuneration is feasible and sufficient weldability of the Material for a component production, for example for a Limousine armor, is present.

In a further development of the alloy, wherein one or more element (s) thereof has the concentration (s) in% by weight: Carbon (C) 0.3 to 0.54, preferably 0.41 to 0.49 Silicon (Si) 0.11 to 0.39 Manganese (Mn) 0.18 to 0.49, preferably 0.25 to 0.38 Chrome (Cr) 1.15 to 1.4 Nickel (Ni) 2.9 to 4.9, preferably 2.56 to 3.9 for use as a material for the above-mentioned products, improved properties thereof can be achieved in the bombardment test. It should also be noted at this point that a further increase in the property level is achieved by lowering the sulfur content below 0.005% by weight.

The inventively achieved advantageous material properties are increasingly pronounced in a bombardment pronounced when the parts are coated to higher strength values of about 1900 N / mm ² . This is also due to the fact that a narrower range of the concentration of each alloying element interacts favorably with the other constituents of the alloy to favor the conversion and formation of the microstructure of the material in the thermal anneal, thereby improving the onset and tempering performance and so on extensive isotropy with low residual stresses.

The technical manufacturing specifications regarding the material, as in the Claim 7, individually and in combination improve on improving the ballistic protection by parts made of it, because through this Stipulations on the isotropy of the material, including microsections, is encouraged. Such can also with a remuneration to higher strengths of the Material carried an increase in material toughness in all directions and the resistance to breakdown of projectiles can be raised.

If the material with the remuneration technical specification that this a strength of greater than 1800 N / mm ² , preferably greater than 2000 N / mm ² , in particular of about 2100 N / mm ² , with a toughness at room temperature greater than SEP 150 J, preferably having greater than 185 J, in particular of about 245 J as measured by (S e teel isen rüfblatt P) in September 1314, are buildable sheets therefrom with the highest breakdown resistance.

By way of examples and by means of Fig. 2, the invention according to claims 5 to 8 are also explained in more detail, wherein FIG. 2 again shows the percentage of held shots depending on the sheet material thickness.

Example 3:

From a slab block of a vacuum-treated steel having a composition of in wt .-% 0.5 carbon (C), 0.32 silicon (Si), 0.45 manganese (Mn), 0.017 Phoshor (P), 0.006 sulfur (p ), 1.25 chromium (Cr), 0.18 molybdenum (Mo), 0.21 tungsten (W), 3.97 nickel (Ni) and with a total of arsenic (As) plus antimony (Sb) plus bismuth ( Bi) plus tin (Sn) plus boron (B) = 0.0085, a sheet having a thickness of 6.8 mm was rolled, which was mechanically tested after application of different tempering technologies. The results of the tests are summarized in Tab. Sample No. Härtetemp. start number rm Rp _0.2 A impact strength hardness ° C ° C N / mm ² N / mm ² % J MW HRC AA 840 120 1 2229 1207 6.1 225 245 226 232 55.5 BB 870 120 1 2227 1133 8.6 220 245 216 227 56 CC 840 120 1 2282 1306 6.5 95 233 173 167 57

In the bombardment test it was found that the plate with the sample designation AA a shot-holding capacity of 95 had, however, an equally thick tempered Carbon steel sheet withstood only 56 out of 100 shots.

Example 4:

A sheet made of pan-metallurgically treated steel having a composition in wt.% Of 0.52 carbon (C), 0.12 silicon (Si), 0.22 manganese (Mn), 0.014 phosphorus (P), 0.003 sulfur ( S), 1.42 chromium (Cr), 0.11 molybdenum (Mo), 0.09 tungsten (W), 0.004 (As + Sb + Bi + Sn + Zn + B), which was subsequently electroslag remelted with a thickness made of 7.5 mm and tempered to a hardness of 57 HRC, yielded at a hardening temperature of 880 ° C and air cooling after tempering at 200 ° C, a yield strength of the material of Rm = 2265 N / mm ² at a notch impact of average 202 J. In the bombardment test in comparison with tempered carbon steel under otherwise identical conditions, a 68.7% higher number of retained shots was recorded.

In one of the further tests, a comparison of inventive Sheets and such from each of the highest values tempered carbon steel and martensite hardening steel using a bombardment test. In Fig. 2 is the Percentage of retained shots as a function of the sheet thickness shown. From a sheet thickness of 5 mm to a thickness of 10 mm proportionally those of martensitaushärtbarem steel and of the Shoots held according to the invention are substantially equal to minor ones Advantages of the material according to the invention in the range over a sheet thickness of 6 mm.

As characteristic it turns out that the use of a Inventive material on the one hand against such a Carbon steel for the same product forms and load criteria has significantly higher ballistic protection and on the other hand a martensitaushärtbaren steel to a much lower proportion of Has alloying elements and thereby in the creation of economic benefits Has.

Claims (8)

1. The use of an alloy, as a material for metal sheets providing ballistic protection, which comprises in percent by weight: carbon (C) 0.26 to 0.79 silicon (Si) 0.2 to 1.2 manganese (Mn) 0.2 to 0.9 chromium (Cr) 1.1 to 7.94 molybdenum (Mo) 0.56 to 3,49 vanadium (V) 0.26 to 1.74 iron (Fe) and impurities as the remainder with the alloying technical proviso that the value of the contents of phosphorus (P) plus sulphur (S) is less than 0.025,
   P + S < 0.025 % by weight,
the concentration of nickel (Ni) is below 0.28
   Ni < 0.28 % by weight
and the sum of the grain boundary effective elements arsenic (As), antimony (Sb), bismuth (Bi), tin (Sn), zinc (Zn) and boron (B) is smaller than 0.011
   As + Sb + Bi + Sn + Zn + B < 0.011 % by weight.

2. The use of an alloy according to claim 1, wherein one or more element(s) thereof comprise(s) the following concentration(s) in percent by weight: carbon (C) 0.36 to 0.64, preferably 0.41 to 0.58 silicon (Si) 0.36 to 0.9, preferably 0.41 to 0.68 manganese (Mn) 0.36 to 0.7, preferably 0.41 to 0.59 chromium (Cr) 1.7 to 5.95, preferably 2.61 to 5.2 molybdenum (Mo) 1.05 to 2,9, preferably 1.3 to 2.7 vanadium (V) 0.36 to 1.25, preferably 0.39 to 0.83

3. The use of an alloy according to claim 1 or 2, with the production technical proviso that the alloy is produced either in a ladle metallurgical way and/or under vacuum treatment and/or by melting or remelting under vacuum and/or by electro-slag remelting, optionally under pressure, and/or in a powder metallurgical way.

4. The use of an alloy, as a material for metal sheets providing ballistic protection, which comprises in percent by weight: carbon (C) 0.3 to 0.6 silicon (Si) 0.08 to 0.59 manganese (Mn) 0.1 to 0.6 chromium (Cr) 0.9 to 1.5 nickel (Ni) 2.4 to 5.5 iron (Fe) and impurities as the remainder with the alloying technical proviso that the value of the contents of phosphorus (P) plus sulphur (S) is less than 0.025,
   P + S < 0.025 % by weight,
the concentration of molybdenum (Mo) is below 0.34 and that of tungsten (W) is below 0.29, the value of the sum of molybdenum (Mo) plus tungsten (W) divided by two not exceeding 0.38 Mo < 0,34 % by weight W < 0,29 % by weight Mo + W/2 < 0,38 % by weight and the sum of the grain boundary effective elements arsenic (As), antimony (Sb), bismuth (Bi), tin (Sn), zinc (Zn) and boron (B) is smaller than 0.011
   As + Sb + Bi + Sn + Zn + B < 0.011 % by weight.

6. The use of an alloy according to claim 5, wherein one or more element(s) thereof comprise(s) the following concentration(s) in percent by weight: carbon (C) 0.36 to 0.54, preferably 0.41 to 0.49 silicon (Si) 0.11 to 0.39, manganese (Mn) 0.18 to 0.49, preferably 0.25 to 0.38 chromium (Cr) 1.15 to 1.4 nickel (Ni) 2.9 to 4.9, preferably 2.56 to 3.9

7. The use of an alloy according to claim 5 or 6, with the production technical proviso that the alloy is produced either in a ladle metallurgical way and/or under vacuum treatment and/or by melting or remelting under vacuum, optionally under pressure, by electro-slag remelting and/or in a powder metallurgical way.

8. The use of an alloy according to any of claims 5 to 7, with the proviso of heat treatment technique that the material has a strength greater than 1800, preferably greater than 2000, particularly more than 2100, N/mm² at a tenacity at room temperature SEP of 150 J, preferably greater than 185 J, particularly above 245 J, when measured according to SEP 1314 (Stahl Eisen Prüfblatt).

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