Method for producing steel components having improved ballistic properties, and use thereof

Abstract

The invention relates to a method for producing steel components having increased resistance to the penetration of ballistic bodies, wherein a sheet steel blank is punched or cut out of a sheet steel strip, the sheet steel blank subsequently undergoes cyclic heat treatment and, after the cyclic heat treatment, the blank is heated to a temperature greater than Ac3 of the steel alloy and is then press-hardened, wherein during the cyclic heat treatment the blank is heated to above Ac3 of the steel alloy and once the target temperature has been reached over the entire cross section of the blank is cooled to a temperature between Ar1 and Bs of the steel alloy, and this is repeated again at least once. The invention also relates to a bombardment-resistant component and the use of same.

Description

[0001] VA25046

[0002] Voestalpine Metal Forming GmbH

[0003] Schmidhüttenstrasse 5

[0004] 3500 Krems

[0005] Austria

[0006] Methods for manufacturing steel components with improved ballistic properties and using the same

[0007] The invention relates to a method for manufacturing steel components with improved ballistic properties and the use thereof.

[0008] Steel armor has been known for a long time, with high-strength steels being used to manufacture armor not only for tanks, but also for ships and aircraft.

[0009] Such steels must possess exceptionally high hardness to withstand the penetration of projectiles. These steel materials are used not only in heavy armor plating such as that used on ships and tanks, but also in the civilian sector for armoring civilian vehicles for personal protection.

[0010] Steel plates are also used for body armor in bulletproof vests and combat helmets. Armor can, of course, also be used where, outside of anticipated ballistic fire such as projectiles, there is an increased risk from flying debris.

[0011] This is the case, for example, with firefighter helmets, other protective helmets, but also in certain areas of industrial manufacturing where temporary or permanent armor must be ordered to protect the people working.

[0012] These types of steel components are naturally quite heavy and, due to the possible manufacturing processes, are usually limited to plates which must be arranged accordingly. VA25046

[0013] This also applies to civilian vehicles, where the plates must be installed accordingly in door areas. Armored plates are also sometimes installed in the floor areas of civilian vehicles, particularly to defend against explosive attacks.

[0014] As previously mentioned, a disadvantage is that such plates are very heavy, making it difficult to ensure sufficient ballistic resistance. Ballistic resistance classes have been standardized, particularly in the civilian sector but also in the military. These ballistic resistance classes include, in particular, the protection classes VPAM 1-10 for civilian applications and, specifically, the special ammunition tests M 193 and NU 3A. These special ammunition tests involve testing against ammunition with increased penetration capabilities, especially armor-piercing ammunition.

[0015] Combat helmets made of aramid and binders are now common. However, these have the disadvantage of being more expensive, heavier, and bulkier than steel helmets. They do, however, offer very good ballistic resistance. But like all plastics, they age, resulting in a significantly shorter lifespan.

[0016] Such armor steel is known, for example, from DE 10 2008 010168B4, in which this armor steel is subjected to a so-called press hardening process, in which the steel material is quenched and simultaneously reshaped.

[0017] From EP 2183401B1, an iron-based alloy with a hardness of more than 550 HBN and a ballistic limit V 50 of at least 150 ft / s according to specification MIL-A-46099C is known.

[0018] CN 1308144A discloses a low-alloy steel alloy for the production of high-impact, high-performance steels with tensile strengths of 1900–2273 MPa, intended for use in bulletproof helmets and vehicles. The steel is manufactured by hardening and tempering, with tempering temperatures of 200–300 °C.

[0019] From “Effect on cyclic annealing on microstructure and mechanical properties of medium carbon steel”, journal of iron and steel research 2016, 23(2; 145 - 150) the pendulum annealing is known, in which a so-called pendulum annealing with twelve pendulum cycles around the Al temperature was carried out.

[0020] From RU 2738870 CI, the application of pendulum annealing for high-speed steels with 3-5 repetition cycles around AC3 is known, where VA25046

[0021] This involves heating to a temperature of Acm + 300°, which means above 1100 °C, after which the material is held and cooled to a temperature of AR1 and kept in the salt bath for 30 minutes.

[0022] From EP 3546602 Al it is known that a heat treatment of the steel is carried out, wherein it is first annealed at a temperature greater than Ac3 and then cooled to transform the microstructure into martensite and / or bainite, followed by a second annealing treatment to temperatures above Ac3.

[0023] The object of the invention is to create a method by which steel components with increased bullet resistance and lower weight can be produced, and in particular steel components with a three-dimensional spatial shape can be produced.

[0024] The problem is solved by a method having the features of claim 1. Advantageous further developments are characterized in the dependent dependent claims.

[0025] According to the invention, a steel material is cut from a strip, thereby producing so-called blanks, i.e., flat steel sheets.

[0026] These flat steel sheets are then subjected to a specially adapted pendulum annealing process and, after the pendulum annealing, are either only hardened or hardened and formed in a press hardening step.

[0027] Cyclic annealing is a heat treatment process that involves heating to a target temperature, holding at that temperature (if necessary) until the material is thoroughly heated, and then cooling to another target temperature, again with a possible holding period for complete cooling. This constitutes a cycle. It has also been found that transformation into martensite and / or bainite during this cyclic heat treatment (cycle) is not advantageous, as any phase transformation should be avoided.

[0028] It was found that the special pendulum annealing process prior to press hardening, and in particular adherence to a specific temperature profile, produces a microstructure VA25046.

[0029] can be produced, which has a very fine martensite even after press hardening and possible subsequent tempering.

[0030] This fine-grained structure with martensite grains, especially those smaller than 3 pm, results in even greater hardness and improved ductility, allowing the material to be made thinner while maintaining comparable ballistic resistance. This can lead to weight savings in armor plating, particularly in applications for land, air, and water vehicles.

[0031] Conversely, with the same thickness, an improved ballistic protection class can be achieved.

[0032] The subsequent press hardening step after pendulum annealing allows the material to be shaped without subsequent temperature steps – apart from tempering – having a negative impact on the microstructure.

[0033] This makes it possible to produce armor components that are, for example, better adapted to the outer skin of a vehicle and can be positioned behind it. In addition to simple plate shapes, more complex forms can also be achieved. These more complex shapes are further improved compared to the previous technology because, while maintaining the same impact resistance, the parts are thinner and therefore more easily shaped.

[0034] Ultimately, depending on the vehicle, even the outer body panels themselves can be made from these materials.

[0035] In addition, protective helmets and especially combat helmets can be manufactured that are less bulky than aramid helmets and have a longer lifespan.

[0036] The invention thus relates in particular to methods for manufacturing steel components with increased resistance to the penetration of ballistic objects, wherein a steel sheet blank is punched or cut from a steel strip, the steel sheet blank is subsequently subjected to cyclic heat treatment, and after the cyclic heat treatment is heated to a temperature greater than Acs of the steel alloy and subsequently press-hardened, wherein during the cyclic heat treatment the blank is heated above Acs of the steel alloy and, after heating through, i.e., after reaching the target temperature in the entire cross-section of the blank, is cooled to a temperature between Ari and Bs of the steel alloy, and this is repeated at least once more. This means that the bainite start (B s VA25046

[0037] Temperatures should not be undercut in order to prevent any structural transformation during the pendulum annealing process.

[0038] The conversion temperatures in degrees Celsius can be calculated as follows:

[0039] 902 -255 [C] + 19 [Si] - 11 [Mn] - 5 [Cr] + 13 [Mo] - 20 [Ni] + 55 [V]

[0040] An= 741.7 - 7.13 [C] - 14.09 [Mn] - 16.26 [Si] + 11.54 [Cr] - 49.69 [Ni]

[0041] Bs = 830 - 270 [C] - 90 [Mn] - 37 [Ni] - 70 [Cr] - 83 [Mo]

[0042] Ms = 539 - 423 [C] - 30.4 [Mn] - 17.7 [Ni] - 12.1 [Cr] - 7.5 [Mo]

[0043] For this purpose, the concentrations of the aforementioned alloying elements in weight percent are inserted into the respective formula.

[0044] In addition, these conversion temperatures, especially Bs, can depend on the cooling rates and shift accordingly. This is known to those skilled in the art from various TTT (time-temperature-conversion) diagrams and can be used for the exact determination of the conversion temperatures.

[0045] According to DIN EN 10052, these temperatures correspond to:

[0046] Acs: Temperature at which the conversion of ferrite to austenite ceases upon heating.

[0047] Ari: Temperature at which the transformation of austenite into ferrite or into ferrite and cementite ends upon cooling.

[0048] Further training stipulates that immediately after the final cooling to a temperature between Ari and Bs of the steel alloy, the circuit board is heated to a temperature above Acs and then press-hardened.

[0049] Further training stipulates that after the final annealing within the cyclic heat treatment, the circuit board is quenched to room temperature at a cooling rate greater than 100 K / s. VA25046

[0050] Further training involves giving the steel sheet blank a three-dimensional shape during press hardening by deep drawing.

[0051] Further training stipulates that press hardening is carried out in such a way that the flat shape of the circuit board is maintained.

[0052] Further training stipulates that the martensite grain size should be less than 4 pm.

[0053] Further training stipulates that the circuit board is coated with a scale protection, in particular a zinc-based coating, before the first annealing process.

[0054] Further training stipulates that the circuit board is heated to a temperature of 10-30 °C above the Acs temperature during cyclic heat treatment.

[0055] Further training stipulates that after reaching the heating temperature above the Ac3 temperature during the cyclic heat treatment, the sheet metal is immediately (< 1 min) removed from the furnace and cooled in the open air to a temperature between the Ari and Bs temperatures.

[0056] Further training stipulates that during cyclic heat treatment, cooling is carried out at a rate between 1 and 20 K / s, preferably 3 to 10 K / s, and particularly 5 to 8 K / s. Adjusting the cooling rate allows for control of both the process speed and the Bs temperature.

[0057] Further development involves cooling the circuit board to a maximum of 50 °C below the annealing temperature during cyclic heat treatment. This can make the process even more advantageous, as the temperature differences during cyclic annealing are kept as small as possible to reliably ensure grain refinement while also minimizing thermal losses due to the multiple cooling steps.

[0058] Further training stipulates that after reaching the cooling temperature within the cyclic heat treatment, reheating begins immediately.

[0059] Further training stipulates that after the final heating temperature is reached, the circuit board is quenched using water or other liquid media.

[0060] Further training stipulates that cyclic heat treatment comprises 2 to 7, in particular 2 to 5 cycles, with each cycle including heating and cooling. VA25046

[0061] Further training stipulates that, for the purpose of press hardening, the cyclically heat-treated circuit board is heated to a temperature 100°C above the Acs temperature and transported into the tool after 3-15 minutes.

[0062] Further training stipulates that the quenching or forming and quenching of the component in the cooled press hardening tool is carried out at a cooling rate that is above the critical hardening rate of the corresponding steel alloy and in particular above 40 °K / s down to a temperature below 200 °C.

[0063] Further training stipulates that after press hardening, tempering is carried out, in particular at or above 100 °C and below the Mss temperature for a duration of 30 min to 400 min.

[0064] Further training stipulates that the engine be cooled down in the open air after starting.

[0065] Further training stipulates the use of a steel with the following composition (all values ​​in weight percent wt-%):

[0066] Element content preferred

[0067] C 0.25-0.50 0.45-0.50

[0068] Si 0.20-0.80 0.20-0.25

[0069] Mn 0.20-2.20 0.25-0.30

[0070] Cr 0.15-1.50 0.19-0.22

[0071] Ni 1.00-4.00 2.70-3.00

[0072] Mon 0.30-0.50 0.40-0.45

[0073] V 0.03-0.30 0.03-0.10

[0074] Nb <0.050 <0.003

[0075] W <0.50 0.05-0.40

[0076] Co <2 0.4-1.8 VA25046

[0077] Ti <0.05 <0.03

[0078] B <0.005 <0.003

[0079] Residual iron (Fe) and unavoidable impurities resulting from the smelting process.

[0080] With such an alloy composition, mechanical properties of tensile strength above 2200 MPa and an elongation at break of > 8% can advantageously be achieved.

[0081] Further training stipulates the use of a steel with the following composition (all values ​​in weight percent wt-%):

[0082] Element content preferred

[0083] C 0.20-0.70 0.45-0.65

[0084] Si 0.20-1.70 0.20-1.20

[0085] Mn 0.20-2.00 0.25-1.20

[0086] Cr 0.15-1.00 0.18-0.25

[0087] Ni 2.00-5.00 3.00-4.00

[0088] Mon 0.05-0.70 0.30-0.50

[0089] V 0.03-0.30 0.03-0.20

[0090] Nb <0.050 <0.004

[0091] W <0.50 <0.30

[0092] Co <3 0.8-2.0

[0093] Ti <0.05 <0.04

[0094] AI <3 0.80-2.00

[0095] Cu <2 0.30-1.80

[0096] B <0.02 <0.01

[0097] Residual iron (Fe) and unavoidable impurities resulting from the smelting process

[0098] With this alternative composition, mechanical properties of tensile strength > 2300 MPa and elongation at break > 9% can be advantageously achieved. The addition of copper (Cu) can significantly increase weather resistance. VA25046

[0099] This will enable maritime applications with demanding weather conditions. Furthermore, copper can further improve mechanical properties through solid solution strengthening and precipitation strengthening. By adding aluminum, the Ms and Mf temperatures can be adjusted, and the high-temperature strength can be increased through the precipitation of intermetallic phases.

[0100] Further training stipulates that if the carbon content is below 0.3 wt.%, the manganese content is adjusted to > 2 wt.%.

[0101] Further training stipulates that the carbon equivalent be converted to C ev from 0.5 to 1.43% especially C ev is set to 0.8 to 0.9%.

[0102] Carbon equivalent is defined by C ev = C + Mn / 6 + (Cr+Mo+V) / 5 + (Ni+Cu) / 15 according to DIN EN 10025.

[0103] Another aspect of the invention relates to a bulletproof steel component manufactured using the method described above according to one of the preceding claims.

[0104] Another aspect of the invention relates to the use of a bulletproof steel component for the armoring of land, sea and air vehicles, for the manufacture of body armor for humans, for the manufacture of combat helmets and protective helmets.

[0105] Further training stipulates that the steel component is designed as a three-dimensional outer skin part or as a component located under the outer skin, adapted to the outer shape of the vehicle.

[0106] The invention is explained by way of example with the aid of a drawing. The drawing shows:

[0107] Figure 1: a temperature-time curve of a first embodiment of a pendulum annealing process according to the invention;

[0108] Figure 2: a temperature-time curve of a second embodiment of a pendulum annealing process according to the invention; VA25046

[0109] Figure 3: a light optical microscopy (LOM) image of the microstructure of a conventionally manufactured bulletproof steel;

[0110] Figure 4: A LOM image of the microstructure of a bulletproof steel produced according to the invention;

[0111] Figure 5: A comparison of the stress-strain curves of conventional steel and steel according to the invention.

[0112] Figures 1 and 2 show two different methods for cyclic heat treatment, i.e., pendulum annealing.

[0113] Figure 1 shows a pendulum annealing process with three cycles, starting from room temperature, in which heating to A C 3 is done and then at a temperature between A ri and B s is cooled down.

[0114] The process involves holding the temperature at least long enough for the target temperature to be reached across the entire cross-section of the circuit board, and then immediately reheating or cooling it again, specifically within 60 seconds. This means that a minimum time is allowed for the sheet metal to reach the target temperature in all areas and across its entire thickness.

[0115] During pendulum annealing, i.e., heat treatment of the steel sheet to a higher temperature and cooling to a temperature between A ri and the B sThe aim is to produce a fine martensitic microstructure with high strength and ductility through repeated cycles after final quenching. Maintaining a temperature above the bainite start temperature is crucial, as diffusion-driven phase transformations are to be avoided. Bainite formation leads to local precipitation of carbides, preferentially at grain boundaries, and depletion of carbon in the austenite, resulting in heterogeneous microstructure islands.

[0116] Upon reheating to A C At 3°C, the previously formed bainite would revert to austenite. These carbide precipitates, containing bainite, would then not be completely dissolved in the next step, but would remain partially intact. These would then hinder grain regeneration by acting as nuclei for coarse grain formation, thereby reducing the homogeneity of the recrystallization and the resulting fine grain after final quenching. VA25046

[0117] Furthermore, the austenite transformation temperature varies depending on the proportion of dissolved or undissolved carbides, as the chemical composition of the austenite changes due to carbon depletion. Accordingly, by avoiding carbide formation, the process parameters can be set more precisely and within narrower process windows.

[0118] This therefore means that the steel can be repeatedly heat-treated at temperatures greater than A. C 3 and cooling to a temperature between A ri and B s A fine grain is produced. Any potential bainite formation during pendulum annealing would impair this effect, as it hinders grain regeneration and disrupts the homogeneity of the austenite.

[0119] The sheet metal is then cooled to room temperature. After this treatment, it can be stored and transported to a press hardening station.

[0120] Preferably, the sheet metal should be stored for a maximum of one week.

[0121] For press hardening, the sheet metal or circuit board is raised above A C 3. The workpiece is heated and then placed in the press hardening tool and quenched and hardened there. Forming can occur during this process. Tempering follows the press hardening.

[0122] Figure 2 shows an embodiment in which, after the last heat treatment cycle, the material is heated directly for press hardening and then the press hardening is carried out.

[0123] Starting the engine may follow here as well.

[0124] Cooling during cyclic heat treatment can be carried out, in particular, to a temperature between Ari and Bs of the steel alloy.

[0125] After the final annealing within the cyclic heat treatment, the circuit board can be quenched to room temperature, particularly with a cooling rate greater than 100°K / s.

[0126] Figure 3 shows a light optical microscopy (LOM) image of a conventional bulletproof steel, revealing its microstructure. The microstructure consists of lath martensite with a grain size greater than 10 pm. The achieved hardness is 587 HV1, the tensile strength is 1970 MPa, and the elongation at break is less than 8%.

[0127] Figure 4 shows, as a comparative example, the steel that has been heat-treated according to the invention. The microstructure VA25046 is achieved through cyclic heat treatment or pendulum annealing.

[0128] Significantly finer. This is also a lath martensite, but with a grain size of less than 4 pm. A hardness of 660 HV1 is achieved, along with a significantly increased tensile strength of 2270 MPa. The elongation at break is > 9%. Overall, the material properties are thus unexpectedly improved in all areas, including hardness, tensile strength, and ductility. It is therefore possible to simultaneously increase two properties that are usually mutually exclusive.

[0129] The corresponding comparative stress-strain diagram is shown in Figure 5.

[0130] According to the invention, the steel sheet blank can be given a three-dimensional shape during press hardening by deep drawing, so that on the one hand reinforcements for the human body can be produced in adapted shapes, but also armor can be adapted to the contour or shape of a land, air or water vehicle, for example adapted to the body of a vehicle.

[0131] As explained above, press hardening can also be carried out in such a way that the flat shape of the circuit board is maintained.

[0132] The circuit board can be coated with an anti-scale coating, particularly a zinc-based coating, before the first annealing process, so that the annealing process can take place without negative surface changes and, in particular, no subsequent cleaning of the scale layer is necessary. This also protects the press hardening tool.

[0133] The cyclic heat treatment is carried out by preferably heating the circuit board to a temperature of 10-30 °C above the Acs temperature.

[0134] After reaching the heating temperature above the Acs temperature, as part of the cyclic heat treatment, the sheet metal is removed from the furnace immediately, i.e. within 60 seconds of reaching the temperature in the entire sheet, and cooled in free air to a temperature between the Ari and Bs temperatures.

[0135] In particular, during cyclic heat treatment, cooling is carried out at a cooling rate between 1 and 20 °K / s.

[0136] It is preferred that the circuit board be cooled to a maximum of 50 °C below the atomic temperature during cyclic heat treatment. VA25046

[0137] Once the cooling temperature is reached during the cyclic heat treatment, reheating begins immediately.

[0138] After the final heating temperature has been reached, the circuit board can be quenched using water or other liquid media.

[0139] The cyclic heat treatment comprises 2 to 7, in particular 2 to 5 cycles, each cycle comprising a heating and cooling phase.

[0140] For the purpose of press hardening, the cyclically heat-treated blanks are heated to a temperature 100 °C above the Acs temperature and transported into the tool after 3-15 minutes, but only after thorough heating.

[0141] In press hardening, the quenching or forming and quenching of the component in the cooled press hardening tool is carried out at a cooling rate that is above the critical hardening rate of the corresponding steel alloy and in particular at over 40 °K / s down to a temperature below 200 °C.

[0142] After press hardening, tempering can follow, especially at or above 100 °C and below the Ms temperature for a duration of 30 min to 400 min.

[0143] After starting, it can be cooled down in the air.

[0144] As an example, a sheet steel plate with the following composition is used:

[0145] Example 1 where all alloying elements are given in weight percent:

[0146] C 0.47

[0147] Si 0.23

[0148] Mn 0.27

[0149] Cr 0.2

[0150] Ni 2.85

[0151] Mo 0.42 VA25046

[0152] V 0.05

[0153] Nb 0.001

[0154] W 0.2

[0155] Co 1

[0156] Ti 0.01

[0157] B 0.0005

[0158] This results in the following calculated values ​​for the temperatures:

[0159] Ac3 = 733.8 °C

[0160] Arl = 595.5 °C

[0161] Bs = 524.5 °C

[0162] This material is heated to a temperature of 800 °C and then subjected to, for example, 3 cycles of annealing, during which it was cooled to a temperature of 560 °C and held at this temperature throughout the entire cross-section of the steel sheet until this temperature was reached.

[0163] Subsequently, a press hardening process was carried out directly from a temperature of 560 °C, whereby the circuit board was heated to 820 °C and cooled at a cooling rate above the critical hardening rate and formed into a component press hardened.

[0164] As a final step, the component was tempered at 150°C for 35 minutes.

[0165] In this example, very good mechanical properties were achieved, including a hardness of 671 HV1 and a tensile strength of 2254 MPa. A martensite grain size of 2.4 pm was also obtained.

Claims

A25046 Voestalpine Metal Forming GmbH Schmidhüttenstrasse 5 3500 Krems Austria Claims 1. Method for manufacturing steel components with increased resistance to penetration by ballistic bodies, wherein a steel sheet blank is punched or cut from a steel strip, the steel sheet blank is subsequently subjected to cyclic heat treatment and after the cyclic heat treatment is heated to a temperature greater than A C 3. The steel alloy is heated and then press-hardened, whereby during the cyclic heat treatment the steel sheet blank above A C 3 of the steel alloy is heated and, after reaching the target temperature, the entire cross-section of the circuit board is cooled to a temperature between A ri and B s The steel alloy is cooled down, and this process is repeated at least once more.

2. Method according to claim 1, characterized in that directly after the final cooling to a temperature between A ri and B s the steel alloy circuit board to a temperature above A C 3 is heated and then press-hardened.

3. Method according to claim 1 or claim 2, characterized in that after the final annealing within the cyclic heat treatment, the circuit board is quenched to room temperature with a cooling rate greater than 100°K / s.

4. Method according to one of the preceding claims, characterized in that the steel sheet blank is given a three-dimensional shape during press hardening by deep drawing.

5. Method according to one of claims 1 to 3, characterized in that the press hardening is carried out in such a way that the flat shape of the circuit board is retained.

6. Method according to one of the preceding claims, characterized in that the martensite grain size is less than 4 pm.

7. Method according to one of the preceding claims, characterized in that the circuit board is coated with a scale protection, in particular a zinc-based coating, before the first annealing process. A25046 8. Method according to one of the preceding claims, characterized in that the circuit board is heated to a temperature of 10-30°C above the A during the cyclic heat treatment. C 3-temperature is heated.

9. Method according to one of the preceding claims, characterized in that after reaching the heating temperature above the A C 3-temperature as part of the cyclic heat treatment, the sheet metal is removed from the oven within less than 60 seconds and cooled in free air to a temperature between Ari and Bs temperature.

10. Method according to one of the preceding claims, characterized in that the cooling during the cyclic heat treatment is carried out with a cooling rate between 1 and 20 °K / s, preferably 3 to 10 K / s, particularly 5 to 8 K / s.

11. Method according to one of the preceding claims, characterized in that the circuit board is subjected to cyclic heat treatment at a temperature of at most 50°C below the A r i- Temperature is cooled.

12. Method according to one of the preceding claims, characterized in that after reaching the cooling temperature within the cyclic heat treatment, reheating begins immediately.

13. Method according to claim 3, characterized in that after the final reaching of the heating temperature, the circuit board is quenched using water or other liquid media.

14. Method according to one of the preceding claims, characterized in that the cyclic heat treatment comprises 2 to 7, in particular 2 to 5 cycles of heating and cooling.

15. Method according to one of the preceding claims, characterized in that, for the purpose of press hardening, the cyclically heat-treated circuit board is heated to a temperature 100°C above the A C It is heated to a temperature of 3 and transported into the tool after 3-15 minutes.

16. Method according to one of the preceding claims, characterized in that the quenching or forming and quenching of the component in the cooled press hardening tool is carried out at a cooling rate which is above the A25046 critical hardening speed and especially above 40°K / s down to a temperature below 200°C.

17. Method according to one of the preceding claims, characterized in that after press hardening, tempering is carried out, in particular at temperatures above 100 °C and below the Ms temperature, for a duration of 30 min to 400 min.

18. Method according to claim 17, characterized in that cooling takes place in air after tempering.

19. Method according to one of the preceding claims, characterized in that a steel of the following composition is used (all values ​​in weight percent wt.%): Element content preferred C 0.25-0.50 0.45-0.50 Si 0.20-0.80 0.20-0.25 Mn 0.20-2.20 0.25-0.30 Cr 0.15-1.50 0.19-0.22 Ni 1.00-4.00 2.70-3.00 Mon 0.30-0.50 0.40-0.45 V 0.03-0.30 0.03-0.10 Nb <0.050 <0.003 W <0.50 0.05-0.40 Co <2 0.4-1.8 Ti <0.05 <0.03 B <0.005 <0.003 Residual iron (Fe) and unavoidable impurities resulting from the smelting process.

20. Method according to one of the preceding claims, characterized in that a steel of the following composition is used (all values ​​in weight percent wt.%): Element content preferred C 0.20-0.70 0.45-0.65 Si 0.20-1.70 0.20-1.20 Mn 0.20-2.00 0.25-1.20 A25046 Cr 0.15-1.00 0.18-0.25 Ni 2.00-5.00 3.00-4.00 Mon 0.05-0.70 0.30-0.50 V 0.03-0.30 0.03-0.20 Nb <0.050 <0.004 W <0.50 <0.30 Co <3 0.8-2.0 Ti <0.05 <0.04 AI <3 0.80-2.00 Cu <2 0.30-1.80 B <0.02 <0.01 Residual iron (Fe) and unavoidable impurities resulting from the smelting process 21. Method according to one of the preceding claims, characterized in that, at a carbon content below 0.3 wt.%, the manganese content is adjusted to above 2 wt.%.

22. Method according to one of the preceding claims, characterized in that the carbon equivalent is based on C ev from 0.5 to 1.43% especially C ev is set to 0.8 to 0.9%.

23. Bulletproof steel component manufactured by a method according to one of the preceding claims.

24. Use of a bulletproof steel component for the armoring of land, sea and air vehicles, for the manufacture of body armor for humans, for the manufacture of combat helmets and protective helmets.

25. Use according to claim 24 wherein the steel component is designed as a three-dimensional outer skin part or as a component lying under the outer skin adapted to the outer shape of the vehicle.

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