Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/12—Both compacting and sintering
  • B22F3/14—Both compacting and sintering simultaneously
  • B22F3/15—Hot isostatic pressing
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C29/00—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides
  • C22C29/005—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides comprising a particular metallic binder
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C33/00—Making ferrous alloys
  • C22C33/02—Making ferrous alloys by powder metallurgy
  • C22C33/0207—Using a mixture of pre-alloyed powders or a master alloy
  • C22C33/0228—Using a mixture of pre-alloyed powders or a master alloy comprising other non-metallic compounds or more than 5% of graphite
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C33/00—Making ferrous alloys
  • C22C33/02—Making ferrous alloys by powder metallurgy
  • C22C33/0257—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements
  • C22C33/0278—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements with at least one alloying element having a minimum content above 5%
  • C22C33/0285—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements with at least one alloying element having a minimum content above 5% with Cr, Co, or Ni having a minimum content higher than 5%
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C33/00—Making ferrous alloys
  • C22C33/02—Making ferrous alloys by powder metallurgy
  • C22C33/0257—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements
  • C22C33/0278—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements with at least one alloying element having a minimum content above 5%
  • C22C33/0292—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements with at least one alloying element having a minimum content above 5% with more than 5% preformed carbides, nitrides or borides
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/10—Ferrous alloys, e.g. steel alloys containing cobalt
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium

Definitions

• the invention relates to a powder metallurgy produced steel sheet, which offers a high protection against bombardment, a use of such a steel sheet and a method for its preparation.
• Sheet metal for vehicle armor in the civil sector are today usually made of alloyed stainless steels.
• the steels used for this purpose mainly come from the field of tempered steels and martensitic hardenable high-strength steels. While the sheets made of tempered steels usually have thicknesses of up to 16 mm, steel sheets produced from martensitic hardenable high-strength steels are usually up to 10 mm thick. Such large sheet thicknesses are required to ensure the required safety shovels.
• the steels used in practice for producing sheets of the above-mentioned type can be produced in a known manner via the route "blast furnace converter".
• martensite-hardenable ultrahigh-strength steels are predominantly obtained by melting in an electric arc furnace, casting into blocks or in the strand and subsequent remelting by electro-slag remelting or vacuum remelting, in particular arc-vacuum remelting. Subsequent diffusion annealing and consequent hot forming, forging and rolling in multiple stages, are then fabricated from the remelted blocks, which have the thickness required for their respective shot resistance. This is typically in the range of 2 mm to 10 mm.
• the case processed steel can according to the US 5,538,683 besides Fe and unavoidable impurities (in% by weight) up to 0.02% C, 10 - 23% Ni, 7 - 20% Co, up to 8% Mo, up to 2.5% Al, up to 0.003% B and up to 0.05% N, with emphasis being placed on the steel is largely free of titanium.
• the thus assembled and processed steel has hardness ranges of 25-50 HRC. However, its resistance to bombardment does not meet the requirements set in practice.
• the object of the invention was to propose a steel sheet suitable for bombardment applications in the civil sector, a preferred use of such a steel sheet and a method suitable for its production, in the simplified production processes with the greatest possible accuracy of the resulting material combined.
• such a steel sheet according to the invention is made of at least two components powder metallurgy, wherein the one component has a hardness of 35 - 55 HRC and the second component has a hardness which is greater than that Hardness of the first component, while in the range of 50-75 HRC, wherein at least one of the components is a steel alloy, which falls under the following basic composition (in wt .-%) up to 0.10% C, up to 0.50% Si, up to 0.50% Mn, up to 0.015% P, up to 0.015% S, 2.0-8.0% Mo, 10.0-20.0% Ni, up to 1.0% Al, 6.0-16.0% Co, up to 3.0% Ti, remainder iron and unavoidable impurities, and the other component either also a steel alloy falling within the basic composition or a non-metallic compound belonging to the group of Oxide ceramics or the group non-oxidic hard materials belongs.
• the other component either also a steel alloy falling within the basic composition or a non-metallic compound belonging to the group of Ox
• a steel sheet with an at least two-phase or two-layer structure is available, which offers at projectile energies of 3200 J and more security against penetration of the projectile.
• ⁇ norm S1314, Austrian Standards Institute Vienna, 2003 it achieves the bulletproof class PM7.
• a sheet obtained according to the invention is able to continue to tighten conditions, such as in the future. Bombardment with Dragonov and a projectile energy of 4000 J, to withstand bullets in the interior.
• martensitaushärtbare higher strength steels are combined with one another according to a first variant of the invention in a sheet according to the invention, which fall under a common base composition.
• the alloy contents, which are involved in the curing in particular the Mo, Co and / or Ti content
• two steels are selected from the basic analysis, of which the first by alloying or by a corresponding treatment in the course of production a hardness of 35 to 55 HRC is brought, while the second alloyed or achieved by a corresponding treatment in the course of the production of the sheet according to the invention a hardness of 50 to 75 HRC.
• a steel covered by the basic composition is combined with a non-metallic component, in which case the partners combined with one another are selected such that one component has a lower hardness and the other component has a higher hardness.
• both components are metal alloys falling below the basic composition, their hardness can be adjusted, for example, by the respective content of Ti and / or Co. As the Ti and / or Co contents increase, the hardness of the respective component is increased. Accordingly, with reduced Ti and / or Co contents, a lower hardness is present.
• the shovel safety of a sheet metal according to the invention can be further increased by combining two components falling below the basic composition, one of which has a hardness falling in the lower hardness range and the other having a higher hardness falling in the upper hardness range, and in addition to these components a third component is associated, which belongs to the group of oxide ceramics or the group of non-oxidic hard substances.
• typical examples of the members of these groups include Al 2 O 3 , B 4 C, SiC, TiC, ZrC, VC, NbC, WC, W 2 C, MO 2 C, V 2 C, BN, Si 3 N 4 , NbN or TiN.
• steel sheets according to the invention are particularly suitable for the production of anti-bombardment components.
• the inventive method of producing bullet-proof steel sheets saves the time-consuming and cost-intensive steps which are always problematic in the state of the art and which are problematic from the production process.
• no electro-slag or vacuum remelting is required in inventive manufacturing method. It also eliminates diffusion annealing, pre-forming by forging and roughing.
• the components which are combined with one another according to the invention can be introduced into the respective press mold separately in layers or together as a mixture.
• the advantages of introducing a powder mixture are that the two different alloys are distributed very homogeneously and without segregation. This has, for example, a positive influence on the distortions that occur during a heat treatment. Therefore, such a homogeneously composed material also shows a very good isotropy of the mechanical properties.
• Another advantage of Introducing the components as a mixture is that in addition ceramic hard materials can be mixed in a similar homogeneous distribution, which is fundamentally not possible in the production of molten metal.
• the layering of the powder allows very simple production of double-layered or multi-layered metal sheets, with the multi-layered metal sheets obtained in this way in principle differing from the previously customary roll-coated or blast-plated metal sheets.
• multi-layered sheets the individual layers must be laboriously connected to each other after mechanical machining by welding together or blasting and rolling.
• the boundary layer between the two joined sheets often not faultless. There may be oxides and other foreign particles that interfere with the bonding of the layers together. In a bombardment, the two plates separate from one another at these points, which leads to a failure of the bombardment test.
• the invention allows a layering of the components present in powder form, which is faster and easier to carry out and in which the influence of foreign particles can be virtually ruled out.
• the individual powder grains flow gently into one another, whereby no rigid boundary layer between the steels with different chemical Composition is created, but a flowing transition, through which the permanently firm clamping of the layers is ensured.
• This type of connection of the two layers is possible without errors over the entire cross section of the block produced. Accordingly, in accordance with the invention stratified trained sheets a particularly secure connection between the layers is ensured even when exposed to high energy shot.
• a process-safe adjustment of the properties of sheet metals according to the invention can be achieved by sawing the ingot obtained after hot isostatic pressing into sinkers, heating the sinkers to a temperature of more than 1100 ° C. and causing them to creep, i. rolled intermediates, the geometry of which does not yet correspond to the sheet metal dimensions, are hot rolled, after which the cambers are cooled starting from a temperature exceeding 1000 ° C. Subsequently, the further processing of the falls then takes place in two stages. In the first stage of this processing, the cusps are first reheated to more than 800 ° C and then rolled to a sheet at a temperature greater than 800 ° C.
• Optimized properties of the resulting sheet arise when the cambers are heated to a temperature of 820 - 920 ° C in the course of their reheating carried out in the first stage of their processing.
• the sheets obtained after the first stage are rolled to final thickness at a temperature less than 820 ° C.
• the rolling in the second stage of the processing of the crevasses is carried out in the form of a thermomechanical treatment.
• a finished hot-rolled sheet is obtained with optimized, very fine-grained structure, which ensures a particularly high security against bullet.
• This optimized safety is given in particular when the parameters in the hot rolling carried out in the second stage of the processing are selected so that a structure with equiaxed grains is established in the sheet obtained.
• the expression of the desired different hardness properties of the components of a steel sheet according to the invention can be assisted by the quakes being quenched in the course of their cooling in water.
• An essential step of the method according to the invention is the heat treatment.
• the hardness of the at least two different components of the steel sheet is adjusted. Practical experiments have shown in this context that an optimal hardness distribution then sets when the steel sheet or a product made of steel sheet at a temperature of 400 - 550 ° C for at least 60 minutes is outsourced.
• the steel sheet according to the invention has a high hardness after the heat treatment, it is in those cases in which a component is to be formed from the steel sheet, favorable if the production of such a component takes place after the hot rolling, but before the heat treatment.
• the sheet produced according to the invention has a still soft state, in which it can be cold formed without problems, for example.
• a hot-rolled sheet according to the invention can be easily bent to form a component, while in the heat-treated state this is only possible with difficulty.
• solution annealing may be carried out after hot rolling and before production of the component. Optimum results of this solution annealing are obtained when the steel sheet is kept at a temperature of 800-1000 ° C. for at least one hour in the course of solution annealing.
• a first steel powder with an average grain size of 170-240 ⁇ m has been provided which, in addition to iron and unavoidable impurities (in% by weight) 0.02% C, 0.05% Si, 0.06% Mn, 0.009% P, 0.004% S, 4.94% Mo, 18.26% Ni, 0.15% Al, 9.11% Co, 0.42% Ti and alloy-containing a maximum achievable by suitable heat treatment hardness of 50 HRC%.
• a second steel powder having an average grain size of 130-210 ⁇ m has been provided, which, in addition to iron and unavoidable impurities (in% by weight), has 0.03% C, 0.08% Si, 0.10% Mn, 0.008%. P, 0.002% S, 5.01% Mo, 17.94% Ni, 0.22% Al, 13.15% Co and 1.76% Ti, and had a maximum attainable hardness of 62 HRC% by alloying with suitable heat treatment ,
• the thus-compounded mixture was filled in a press mold in which it was pressed into a block at a temperature of 1150 ° C and a pressure of 1000 bar.
• the resulting ingot was then sawn into blanks which were heated to a temperature of 1240 ° C and then hot rolled to precipitates.
• the 1050 ° C hot falls have then been quenched to a temperature of 100 ° C.
• the falls were processed in two stages to hot-rolled sheet. During the first stage of this processing, the cambers were reheated to a temperature of 910 ° C and hot rolled from this temperature.
• the sheets were hot rolled a second time to a final thickness of 8.7 mm at a temperature of less than 820 ° C so that the resulting hot-rolled sheets each have a structure with equiaxial had trained grains. If a component is to be formed from the sheet, which is to be used for example as armor in a car door, it would be cold formed in practice at this point from the hot rolled, not yet hardened sheet. Subsequently, or as in the test operation described here, immediately after the second hot rolling, the hot-rolled sheets have been aged at a temperature of 480 ° C for 8 hours to adjust the hardness of the two components.
• the steel sheet thus obtained had a mixed hardness of 58.5 HRC.
• nine bombardment tests were carried out in the firing channel, the results of which are summarized in Table 1.
• the distance between the mouth of the weapon and the sample at an impact angle of 90 ° was 10 m. It was found in each of the hits a slight buckling on the back, without causing the formation of cracks.
• a first powder layer consisting of the first powder having a lower hardness potential was first introduced into the compression mold.
• a second powder layer was applied, which consisted of the second, a higher hardness potential possessing steel powder.
• the proportion of the powder having the lower hardness potential on the total powder amount stacked in the press die was 33% by volume, while the proportion of the powder with the higher hardness potential was 66% by volume.
• the total amount of powder layered in the compression mold was then compressed into a block at a temperature of 1150 ° C. and a pressure of 1000 bar.
• the resulting ingot was then sawn into blanks which had been heated to a temperature of 1240 ° C and then hot rolled to precipitates.
• the 1050 ° C hot falls were then quenched to a temperature of 120 ° C.
• the cambers were reheated to a temperature of 910 ° C in a first stage of their further processing and hot rolled starting from this temperature in the first step.
• the sheet obtained after the first hot rolling, respectively has been finish hot rolled at a rolling temperature of less than 820 ° C to a steel sheet having a final thickness of 8.6 mm and equiaxed grains.
• the steel sheet thus obtained was stored at a temperature of 480 ° C for 8 hours, which under the conditions prevailing in practice in this case before outsourcing, the hot rolled sheet would be formed into a component, if desired would.
• the steel sheet thus obtained had a hardness of 62 HRC on its side formed by the powder having the higher hardness potential, while on its side formed by the powder having a lower hardness potential other side a hardness of 52 HRC could be measured.

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• Chemical & Material Sciences (AREA)
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• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Manufacturing & Machinery (AREA)
• Powder Metallurgy (AREA)
• Manufacture Of Metal Powder And Suspensions Thereof (AREA)

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• 2006
  • 2006-12-07 DE DE102006058066A patent/DE102006058066B3/de not_active Expired - Fee Related
• 2007
  • 2007-12-07 EP EP07122626A patent/EP1930456A3/fr not_active Withdrawn

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