EP4244473A1 - Outil de formage à haute température - Google Patents

Outil de formage à haute température

Info

Publication number
EP4244473A1
EP4244473A1 EP21805347.8A EP21805347A EP4244473A1 EP 4244473 A1 EP4244473 A1 EP 4244473A1 EP 21805347 A EP21805347 A EP 21805347A EP 4244473 A1 EP4244473 A1 EP 4244473A1
Authority
EP
European Patent Office
Prior art keywords
forming tool
molybdenum
temperature forming
ppmw
temperature
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP21805347.8A
Other languages
German (de)
English (en)
Inventor
Michael EIDENBERGER-SCHOBER
Michael ANDROSCH
Alexander LORICH
Robert Storf
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Plansee SE
Original Assignee
Plansee SE
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Plansee SE filed Critical Plansee SE
Publication of EP4244473A1 publication Critical patent/EP4244473A1/fr
Pending legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B25/00—Mandrels for metal tube rolling mills, e.g. mandrels of the types used in the methods covered by group B21B17/00; Accessories or auxiliary means therefor ; Construction of, or alloys for, mandrels or plugs
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C27/00—Alloys based on rhenium or a refractory metal not mentioned in groups C22C14/00 or C22C16/00
    • C22C27/04—Alloys based on tungsten or molybdenum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/04—Making non-ferrous alloys by powder metallurgy
    • C22C1/05—Mixtures of metal powder with non-metallic powder
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B17/00—Tube-rolling by rollers of which the axes are arranged essentially perpendicular to the axis of the work, e.g. "axial" tube-rolling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B19/00—Tube-rolling by rollers arranged outside the work and having their axes not perpendicular to the axis of the work
    • 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
    • B22F3/16—Both compacting and sintering in successive or repeated steps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B19/00—Engines characterised by precombustion chambers
    • F02B19/10—Engines characterised by precombustion chambers with fuel introduced partly into pre-combustion chamber, and partly into cylinder
    • F02B19/1004—Engines characterised by precombustion chambers with fuel introduced partly into pre-combustion chamber, and partly into cylinder details of combustion chamber, e.g. mounting arrangements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B19/00—Engines characterised by precombustion chambers
    • F02B19/10—Engines characterised by precombustion chambers with fuel introduced partly into pre-combustion chamber, and partly into cylinder
    • F02B19/1004—Engines characterised by precombustion chambers with fuel introduced partly into pre-combustion chamber, and partly into cylinder details of combustion chamber, e.g. mounting arrangements
    • F02B19/1014—Engines characterised by precombustion chambers with fuel introduced partly into pre-combustion chamber, and partly into cylinder details of combustion chamber, e.g. mounting arrangements design parameters, e.g. volume, torch passage cross sectional area, length, orientation, or the like
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B19/00—Engines characterised by precombustion chambers
    • F02B19/10—Engines characterised by precombustion chambers with fuel introduced partly into pre-combustion chamber, and partly into cylinder
    • F02B19/1019—Engines characterised by precombustion chambers with fuel introduced partly into pre-combustion chamber, and partly into cylinder with only one pre-combustion chamber
    • F02B19/108—Engines characterised by precombustion chambers with fuel introduced partly into pre-combustion chamber, and partly into cylinder with only one pre-combustion chamber with fuel injection at least into pre-combustion chamber, i.e. injector mounted directly in the pre-combustion chamber
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B19/00—Engines characterised by precombustion chambers
    • F02B19/12—Engines characterised by precombustion chambers with positive ignition
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B19/00—Engines characterised by precombustion chambers
    • F02B19/16—Chamber shapes or constructions not specific to sub-groups F02B19/02 - F02B19/10
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M21/00—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form
    • F02M21/02—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form for gaseous fuels
    • F02M21/0218—Details on the gaseous fuel supply system, e.g. tanks, valves, pipes, pumps, rails, injectors or mixers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M21/00—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form
    • F02M21/02—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form for gaseous fuels
    • F02M21/0218—Details on the gaseous fuel supply system, e.g. tanks, valves, pipes, pumps, rails, injectors or mixers
    • F02M21/0248—Injectors
    • F02M21/0281—Adapters, sockets or the like to mount injection valves onto engines; Fuel guiding passages between injectors and the air intake system or the combustion chamber
    • 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
    • B22F3/24—After-treatment of workpieces or articles
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C2202/00—Physical properties
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
    • F02F1/00—Cylinders; Cylinder heads 
    • F02F1/24—Cylinder heads
    • F02F1/242—Arrangement of spark plugs or injectors
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/30—Use of alternative fuels, e.g. biofuels

Definitions

  • the present invention relates to a high-temperature forming tool with the features of the preamble of claim 1 and a method for producing a high-temperature forming tool, and a use thereof.
  • high-temperature forming tools are used to designate forming tools for shaping high-strength materials, such as high-alloy, heat-resistant steels.
  • Shaping typically takes place at temperatures in excess of 1000°C, referred to as high temperature for the present application.
  • high-temperature forming tools in the context of this application include:
  • Hole domes (engl. Piercing plugs), as they are used for the production of seamless tubes, stamps, as they are used, for example, in extrusion, and dies, as they are used, for example, in the extrusion of metals.
  • a heated billet is typically drawn over the piercer in a cross-rolling process such as the Mannesmann process.
  • the piercing mandrel widens and smoothes the inside diameter.
  • the resulting thick-walled shell is stretched into a finished tube in subsequent rolling steps.
  • the punch When metals are extruded, the punch displaces material from a workpiece, with reverse extrusion also covering sections of the punch forming a contour of the workpiece to be produced.
  • material is pressed through a shaping die to shape it.
  • the requirements for the material of the high-temperature forming tool are in particular high heat resistance and resistance to thermal and corrosive attack.
  • blanks (blocks for the example of pipe production) are brought to temperatures of up to 1300°C for forming.
  • temperatures up to 1300°C for forming.
  • considerable forces are required for forming (perforating the block, for example in the manufacture of pipes).
  • high-temperature forming tools made from high-temperature steels have to be recooled between forming operations in order not to exceed a permissible operating temperature of the material of the high-temperature forming tool or to ensure a sufficiently high strength of the high-temperature forming tool in use.
  • molybdenum-based alloys have also been proposed for the production of high-temperature forming tools.
  • German patent DE102007037736 B4 describes a piercing mandrel and a mandrel rod made from a molybdenum material which has a molybdenum content of 75% by weight or more, preferably 80% by weight or more, preferably 85% by weight or more and more preferably 90% by weight or more. More preferably, the molybdenum material proposed therein has a titanium content of 0.5% by weight or more, a zirconium content of 0.08% by weight or more and a carbon content of 0.01 to 0. 04% by weight.
  • TZM molybdenum alloy
  • TZM molybdenum alloy
  • the higher high-temperature strength of the proposed molybdenum alloy allows multiple piercings to be carried out without the piercing mandrel having to be cooled in between. As a result, the cycle times can be further reduced, or, to put it another way, more perforations can be made within a certain time.
  • the object of the present invention is to specify an improved high-temperature forming tool.
  • the high-temperature forming tool should be economically viable.
  • the high-temperature forming tool consists at least partially of a molybdenum-based alloy with a molybdenum content of >90 wt.%, the molybdenum-based alloy in one is in the pressed-sintered state and has a thermal shock resistance in the pressed-sintered state of at least 250 K, which thermal shock resistance is defined as the quotient of:
  • the yield point ReH is determined in a tensile test according to the DIN EN ISO 6892-1 standard.
  • the modulus of elasticity E is determined according to DIN EN ISO 6892-1, Appendix G.
  • the thermal expansion coefficient a is determined using a dilatometer measurement.
  • the molybdenum base alloy characterized in this way forms a base material of the high-temperature forming tool.
  • the high-temperature forming tool preferably consists entirely of this molybdenum-based alloy.
  • the molybdenum base alloy is powder metallurgical (in short: "powder metallurgical" molybdenum base alloy) and consequently has a sintered structure.
  • a sintered structure differs significantly and is immediately recognizable to a person skilled in the art from a cast structure.
  • Features of a sintered structure, in particular the sintered structure of a molybdenum-based alloy include a finer and more uniform grain structure compared to a cast structure.
  • a cast structure has fewer pores than a sintered structure. Compared to cavities in a cast structure, the pores of a sintered structure are evenly distributed.
  • Chemical homogeneity is also generally better with a powder-metallurgical material than with one produced by smelting. Furthermore, the powder metallurgical route is more economical, particularly in the case of refractory metals. Among other things, this is because sintering takes place well below a melting temperature. If the yield point ReH cannot be determined, the 0.2% yield point Rpo.2 should be used as a substitute. The 0.2% yield point (i.e. elongation with 0.2% plastic deformation) can be determined using a tensile test according to DIN EN ISO 6892-1.
  • the thermal shock resistance defined in this way has the unit Kelvin [K] and can be interpreted as a temperature difference that the material in question can withstand without damage. Exceeding the yield point is considered damage here.
  • thermal shock resistance is above 260 K or even above 275 K.
  • the material can then withstand even greater temperature gradients.
  • a high-temperature forming tool with the features according to the invention has extremely advantageous technological properties.
  • a high-temperature forming tool according to the invention can thus be cooled particularly abruptly without being damaged. It has been shown that in practice it is important that a high-temperature forming tool is suitable for intensive cooling if the user wants to achieve short cycle times between forming operations.
  • high-temperature forming tools are produced from a semi-finished product obtained by rolling or forging, as a result of which a forming structure is present according to the state of the art.
  • the molybdenum base alloy according to the invention is in a pressed-sintered state.
  • a microstructure characterized as pressed-sintered is present when the material has undergone essentially no shaping, in particular no shaping at all. “Essentially” undeformed here means that no significant shape-changing and/or cross-section-changing deformation was applied. Minor superficial reshaping, such as through a skin pass or calibration pass, smooth rolling, shot peening or the like is not to be regarded as a significant reshaping that changes the shape and/or cross section.
  • the relative density of the base material of the high-temperature forming tool ie the molybdenum-based alloy
  • the relative density characterizes the ratio of the actual density of a substance under consideration to the nominal density of the corresponding material.
  • the nominal density is 10.22 g/cm3. If a molybdenum body has a density of only 9.2 g/cm3, the relative density is around 90% and the porosity is 10%.
  • the relative density is particularly preferably between 91% and 96%, more preferably 94% ⁇ 1%.
  • the buoyancy method is used to determine relative density.
  • the essentially undeformed state is thus characterized by the presence of pores - in contrast to a deformed state, such as by rolling or forging, where there is usually approximately 100% density.
  • the grain growth-inhibiting effect of the pores is particularly advantageous for the application in question. This ensures that the microstructure does not coarsen, or only to a small extent, when used at high temperatures. A grain coarsening can have a negative effect on the mechanical parameters relevant to the application.
  • the pressed-sintered state can be described with regard to the microstructure, among other things, in such a way that there is no forming texture.
  • One Strain texture marks a preferred crystallographic orientation of the grains caused by strain.
  • a forming texture can be detected, for example, by EBSD (electron backscatter diffraction) measurements on metallographic sections.
  • EBSD electron backscatter diffraction
  • the pressed-sintered microstructure can be characterized by a grain aspect ratio (GAR).
  • GAR grain aspect ratio
  • the grain aspect ratio can be expressed as a GAR value, where the GAR value indicates the ratio of a grain length to a grain width.
  • a grain aspect ratio greater than 1 means that the grains have a greater elongation in a longitudinal direction than across it. In other words, elongated grains are then present.
  • the high-temperature forming tool more precisely the molybdenum base alloy forming the high-temperature forming tool, has an average grain aspect ratio with a GAR value of less than 1.5, in particular less than 1.2.
  • a grain aspect ratio with a GAR value of 1 means equal expansion of the grains in a longitudinal direction as transversely.
  • a grain aspect ratio with a GAR value of 1 ⁇ 10% is particularly preferred in the high-temperature forming tool, and a GAR value of 1 ⁇ 5% is even more favorable.
  • a transformation - such as a forging - would typically result in a grain aspect ratio with a GAR value of >1.5.
  • the GAR value is determined by image analysis on a metallographic sample by determining an average grain length and an average grain width therein, and the GAR value results as the quotient of the average grain length divided by the average grain width.
  • An evaluation of at least 10 grains is favorable for determining the mean grain length or the mean grain width.
  • the extent of a grain in a longitudinal direction is considered to be the grain length, and the extent of the grain transversely to it is considered to be the grain width.
  • Isotropic structural properties mean that, in contrast to a forming structure, the structure of a high-temperature forming tool according to the invention essentially has the same properties in all spatial directions. This is particularly relevant for the mechanical and thermophysical properties.
  • the production of the high-temperature forming tool in a press-sintered state is more favorable than a production by forming, such as forging.
  • a basic shape of the high-temperature forming tool can already be specified on the powder compact, which powder compact is also particularly easy to process.
  • a pressed-sintered state describes a structural state as it is set in a representation, in particular by press-sintering, but can also be set, for example, by a representation of hot isostatic pressing (HIP) or hot pressing.
  • HIP hot isostatic pressing
  • press sintering (“p/s” for short) when a component is produced by pressing a powder or a powder mixture to form a green compact and then sintering it, in particular sintering it without pressure.
  • the powder can be pressed, for example, in a die or, for example, cold-isostatically in a rubber hose. This is the simplest and cheapest method for setting a pressed-sintered state of an actual high-temperature forming tool.
  • the present invention follows a different path. Because even if a high-temperature forming tool withstands particularly high operating temperatures, the process becomes uneconomical if the workpiece produced (for example a tube or a profile) is damaged during production - as extensive technological tests by the applicant have shown.
  • the invention is based on the finding that intensive cooling of the high-temperature forming tool is essential for the method to be carried out economically. It is the applicant's surprising finding that the decisive parameter for an economic use of the advantages of molybdenum base alloys is the ability to withstand a temperature difference without damage - and not a further increase in high-temperature strength and/or service temperatures.
  • a thermal shock resistance of greater than or equal to 250 K of the molybdenum base alloy used allows the high-temperature forming tool to be intensively cooled during or between forming without damage occurring.
  • intensive cooling can take place between perforations and/or during a perforation. In this way, the fundamentally favorable property of a high high-temperature strength of molybdenum-based alloys can also be exploited in a technologically and economically advantageous manner.
  • the high-temperature forming tool preferably consists entirely of the molybdenum-based alloy with the features defined above.
  • the thermal shock resistance results from the quotient described above, which includes the yield point.
  • the yield point is therefore only one of several parameters. Provision is preferably made for the molybdenum-based alloy to have a yield strength ReH of at least 400 MPa at room temperature. This development emphasizes the advantage of a high level of the yield point ReH at room temperature.
  • the 0.2% yield point can be used as a substitute.
  • the high-temperature forming tool consists of a material that has an elongation at break (usually denoted by the symbol "A") of at least 8% in a tensile test at room temperature. , preferably greater than 10%, more preferably greater than 15%.
  • the elongation at break A is determined in a tensile test according to the DIN EN ISO 6892-1 standard.
  • this property means that the high-temperature forming tool still has reserves, even with experienced plastic strain, before failure through fracture occurs.
  • the molybdenum-based alloy which according to the invention is in a pressed-sintered state, to have an elongation at break of at least 8%, preferably greater than 10%, more preferably greater than 15%.
  • the base material of the high-temperature forming tool ie the molybdenum-based alloy
  • the fracture toughness Kic expresses the ability of a material with cracks, i.e. after previous damage, to withstand mechanical stress.
  • the fracture toughness Kic is determined according to ASTM E 399.
  • a sufficiently high fracture toughness at room temperature is important, particularly in the case of a strongly recooled high-temperature forming tool, which is frequently subjected to jerky and/or impact loads. It is preferably provided that a brittle-ductile transition temperature of the molybdenum base alloy determined in the bending test is ⁇ 60°C.
  • the brittle-ductile transition temperature is more preferably ⁇ 50°C, in particular ⁇ 40°C.
  • the ductile brittle transition temperature marks a transition of the fracture mechanism in a material from fracture behavior with low energy absorption and/or elongation at fracture (i.e. brittle material behavior) to fracture with high energy absorption and/or or elongation at break.
  • a low brittle-ductile transition temperature therefore means good-natured, because ductile, material behavior even at low temperatures.
  • a brittle-ductile transition temperature is ⁇ 60°C, more preferably ⁇ 50°C, in particular ⁇ 40°C.
  • the high-temperature forming tool can then also be used after uncontrolled and/or prolonged water cooling without the risk of breakage being significantly increased compared to a preheated state. Technologically and economically, this is important because the cooling conditions do not need to be monitored or even regulated or controlled in a complex manner.
  • the base material proposed for the high-temperature forming tool reaches at least a bending angle of 20° at 60°C.
  • the molybdenum base alloy with a molybdenum content of > 99.0% by weight, a boron content "B" of > 3 ppmw and a carbon content "C” of > 3 ppmw has a significantly increased ductility compared to conventional, powder-metallurgical, pure molybdenum (Mo). and an increased yield point Rpo,2.
  • the molybdenum base alloy more preferably has a molybdenum content of >99.93% by weight, a boron content “B” of >3 ppmw and a carbon content “C” of >3 ppmw.
  • the total proportion "BuC” of carbon and boron is in the range of 15 ppmw ⁇ "BuC" ⁇ 50 ppmw, in particular in the range of 25 ppmw ⁇ "BuC" ⁇ 40 ppmw, and an oxygen proportion "O" in the range of 3 ppmw
  • the molybdenum base alloy has a molybdenum content of > 99.93% by weight, a boron content "B” of > 3 ppmw and a carbon content "C” of > 3 ppmw, with the total content (i.e. the sum ) of carbon and boron "BuC" in the range of 15 ppmw
  • a maximum content of tungsten (W) is ⁇ 330 ppmw.
  • a maximum proportion of other impurities is ⁇ 300 ppmw. This expresses the fact that an even closer control of the chemical composition is favorable for the expression of the preferred mechanical-technological properties.
  • the grain boundary strength of molybdenum is reduced by segregation of oxygen and possibly other elements, such as nitrogen and phosphorus, in the area of the grain boundaries.
  • a combination with a low maximum content of other impurities and of tungsten (W) is also beneficial.
  • the proportions of the different elements are determined by chemical analysis.
  • the proportions of most metallic elements e.g. Al, Hf, Ti, K, Zr, etc.
  • the ICP-MS analysis method mass spectroscopy with inductively coupled plasma
  • the boron proportion using the ICP-MS analysis method mass spectroscopy with inductively coupled plasma
  • the carbon content determined via combustion analysis combustion analysis
  • the oxygen content determined via hot extraction analysis carrier gas hot extraction
  • the boron content and the carbon content are each >5 ppmw.
  • certified content information for boron and carbon can typically be specified above 5 ppmw.
  • low boron and carbon contents it should be noted that boron and carbon below a respective proportion of 5 ppmw can also be clearly detected and their proportions can be determined quantitatively (at least if the respective proportion is > 2 ppmw), but the proportions are in in this area - depending on the analysis method - sometimes no longer specified as a certified value.
  • the total proportion of carbon and boron “BuC” is in the range of 25 ppmw ⁇ “BuC” ⁇ 40 ppmw.
  • the boron content “B” is in the range of 5 ppmw ⁇ “B” ⁇ 45 ppmw, more preferably in the range of 10 ppmw ⁇ “B” ⁇ 40 ppmw.
  • the carbon content “C” is in the range of 5 ⁇ “C” ⁇ 30 ppmw, more preferably in the range of 15 ⁇ “C” ⁇ 20 ppmw.
  • both elements (B, C) are contained in such a high and at the same time in such a sufficient quantity in the molybdenum base alloy that their advantageous interaction is clearly noticeable, but at the same time the carbon contained and the boron contained do not have an adverse effect.
  • the effect of carbon is to keep the oxygen content low in the molybdenum base alloy and of boron to allow a sufficiently low carbon content while achieving high ductility and high strength.
  • the oxygen content "0" is in the range of 5 ⁇ "0"
  • a low oxygen content can be set by using starting powders with a low oxygen content (e.g. ⁇ 600 ppmw, in particular ⁇ 500 ppmw), sintering in a vacuum, under a protective gas (e.g. argon) or preferably in a reducing atmosphere (in particular in a hydrogen atmosphere or in an atmosphere with H2 partial pressure), as well as by providing a sufficient carbon content in the starting powders.
  • a low oxygen content e.g. ⁇ 600 ppmw, in particular ⁇ 500 ppmw
  • a protective gas e.g. argon
  • a reducing atmosphere in particular in a hydrogen atmosphere or in an atmosphere with H2 partial pressure
  • the maximum proportion of impurities from zirconium (Zr), hafnium (Hf), titanium (Ti), vanadium (V) and aluminum (Al) is ⁇ 50 ppmw in total.
  • the proportion of each element in this group (Zr, Hf, Ti, V, Al) is preferably ⁇ 15 ppmw.
  • the maximum proportion of impurities from silicon (Si), rhenium (Re) and potassium (K) is ⁇ 20 ppmw in total.
  • the proportion of each element of this group (Si, Re, K) is preferably ⁇ 10 ppmw, in particular
  • the effect attributed to potassium is that it reduces the grain boundary strength, which is why the lowest possible proportion is desirable.
  • Zr, Hf, Ti, Si and Al are oxide formers and could in principle be used to counteract an enrichment of oxygen in the area of the grain boundaries by binding the oxygen (oxygen getter) and thus in turn to increase the grain boundary strength. In some cases, however, they are suspected of reducing ductility, especially when they are present in large quantities. A ductilizing effect is ascribed to Re and V, ie they could fundamentally increase the ductility are used. However, the addition of additives (elements/compounds) means that they can have a disruptive effect depending on the conditions of use.
  • the molybdenum base alloy has a total proportion of molybdenum and tungsten of >99.97% by weight.
  • a proportion of tungsten ⁇ 330 ppmw is not critical for the application mentioned and is typically caused by the Mo extraction and powder production.
  • the molybdenum base alloy has a molybdenum content of >99.97% by weight, i.e. it consists almost exclusively of molybdenum.
  • the carbon and the boron are in total at least 70% by weight, based on the total content of carbon and boron, in dissolved form (they do not therefore form a separate phase).
  • boron may be present as the Mo2B phase, although this is not critical to a small extent. If at least a high proportion (e.g. >70% by weight, in particular >90% by weight) of the carbon and the boron are in solution, they can segregate at the grain boundaries and fulfill the effect explained above to a particularly high degree.
  • each of the elements B and C individually also satisfies the specified limit values.
  • the features of the high thermal shock resistance of the molybdenum-based alloy in the pressed-sintered state can be achieved, as described above, via various combinations of micro-doping elements, discussed using the example of carbon and boron.
  • microdoping elements and combinations of microdoping elements other than carbon and boron are also conceivable.
  • the invention is therefore not necessarily based on a molybdenum-based alloy with the discussed alloying strategy based on the microdoping elements Limited carbon and boron.
  • An alternative alloying strategy would be ductilization by rhenium, for example.
  • the molybdenum base alloy forming the high-temperature forming tool exhibited the following typical material characteristics on the pressed-sintered, i.e. non-formed material at room temperature:
  • the density of the molybdenum base alloy forming the high-temperature forming tool was around 9.4 g/cm3, corresponding to a relative density of around 92%, with the density of molybdenum being 10.2 g/cm3.
  • the levels of carbon and boron were each around 15 pg/g.
  • the molybdenum content was around 99.97% by weight. Typical impurity supplement to 100%.
  • the modulus of elasticity scales with the relative density and was determined to be around 305,000 MPa.
  • the coefficient of thermal expansion a of the molybdenum base alloy was 5.2 x 10- 6 [K- 1 ].
  • thermal shock resistance was defined for the selected example as the quotient of:
  • the high-temperature forming tool is designed as a perforated dome. Tests by the applicant have shown that the properties of the molybdenum base alloy defined above are particularly advantageous when used on a piercing mandrel. Protection is also sought for the use of a high-temperature forming tool according to one of the preceding claims for the production of tubes or profiles, in particular of high-strength metals, in particular of high-alloy steels.
  • the use of a forming tool with the properties specified above has proven particularly effective.
  • the profile of properties according to the invention is of particular advantage in the case of perforations in high-alloy steels in a (cross-piercing) rolling process.
  • the use of a die according to one of the preceding claims is particularly advantageous, because the profile of properties also comes into its own with this high-temperature forming.
  • the advantages of the robustness as well as the economy of the high-temperature forming tool can be experienced by the user.
  • Protection is also sought for a method of making the high temperature forming tool.
  • Molybdenum base alloys are typically fabricated into components for industrial scale via powder metallurgy routes. Melt metallurgy is typically impractical and/or uneconomical for refractory metals.
  • a powder or a powder mixture is usually pressed into a green body, then sintered and then formed into a semi-finished product by rolling, forging and the like. Deviating from this usual production route, the production of the high-temperature forming tool is carried out according to the invention without or essentially without plastic shaping.
  • the method for producing the high-temperature forming tool is characterized by the following steps: a. pressing a powder mixture of molybdenum powder and powders containing boron and carbon into a green body; b. Optionally, machining the green body to approximate a final shape of the piercer; c. sintering the green body in an anti-oxidation atmosphere with a dwell time of at least 45 minutes at temperatures in the range of 1,600°C - 2,200°C to obtain a sintered blank of the high-temperature forming tool; i.e. Optional finishing of the sintered blank to the finished high-temperature forming tool, here to the piercing mandrel.
  • powders containing boron and carbon can be molybdenum powders that contain a corresponding proportion of boron and/or carbon. It is important here that the starting powder used to press the green body contains sufficient amounts of boron and carbon and that these additives are distributed as evenly and finely as possible in the starting powder.
  • the sintering step comprises a heat treatment for a residence time of 45 minutes to 12 hours (h), preferably 1-5 h, at temperatures in the range of 1800°C - 2100°C.
  • the sintering step is carried out in a vacuum, under protective gas (e.g. argon) or preferably in a reducing atmosphere (in particular in a hydrogen atmosphere or in an atmosphere with partial H2 pressure).
  • the representation of a high-temperature forming tool with the properties according to the invention such as thermal shock resistance in the pressed-sintered state is not necessarily limited to a molybdenum-based alloy with the discussed alloying strategy based on the microdoping elements carbon and boron. Much more the process claim specifies a particularly advantageous and economical way.
  • microdoping elements and combinations of microdoping elements than carbon and boron or another alloying strategy are also conceivable.
  • Fig. 1 a perspective view of an embodiment of a
  • Fig. 3 a piercing mandrel in cross section
  • FIG. 5a, 5b views of a further exemplary embodiment of a high-temperature forming tool—example of a stamp
  • Fig. 6 schematically shows the production route of a high-temperature forming tool using the example of a hole dome
  • FIG. 1 schematically shows a high-temperature forming tool according to the invention, which is designed as a piercing mandrel 1 in this exemplary embodiment.
  • the piercing mandrel 1 has a tip section 2 and a rear section 3 .
  • the piercing mandrel 1 typically carried by a dome rod (not shown) for which a socket is formed.
  • FIG. 2 shows the piercing mandrel 1 in a side view.
  • the piercing mandrel 1 is designed as a rotationssym metric with respect to an axis of symmetry L in the embodiment.
  • FIG. 3 shows the piercing mandrel 1 in a cross section.
  • An optional device 4 for cooling and/or instrumentation of the hole dome 1 is shown here.
  • the device 4 is designed as a bore.
  • FIGS. 4a and 4b show views of a further exemplary embodiment of a high-temperature forming tool of the invention, here using the example of a die 1 for metal forming.
  • FIG. 4a shows a perspective view
  • FIG. 4b shows a cross section.
  • Dies of the type shown here are used, for example, in the extrusion of high-alloy steels.
  • the die 1 can of course take on different shapes and in particular different cross-sectional shapes.
  • FIGS. 5a and 5b show views of a further exemplary embodiment of a high-temperature forming tool of the invention, here using the example of a punch 1 for metal forming.
  • FIG. 5a shows a perspective view
  • FIG. 5b shows a cross section.
  • a device 4 for introducing a cooling medium can be formed.
  • device 4 is also set up as a receptacle.
  • stamps of the type shown here are used, for example, in reverse extrusion of high-alloy steels.
  • the stamps can also take on forms that deviate from the form shown here.
  • FIG. 6 schematically shows the production route for a high-temperature forming tool according to the invention using the example of a piercing mandrel 1 .
  • step a) a powder mixture of molybdenum powder and powders containing boron and carbon is pressed to form a green body G.
  • step b) shows a processing of the green body G to approximate a final shape of the hole dome 1 .
  • step c) the green body G is sintered in order to obtain a sintered blank R of the hole dome 1 .
  • the piercing mandrel 1 is obtained in step d) through the sintered blank R.
  • the sintered blank R can be processed.
  • FIG. 7 shows a diagram of the brittle-ductile transition temperature for various materials that are fundamentally suitable for high-temperature forming tools.
  • Bending angles in [°] of three-point bending specimens are plotted as the ordinate against the temperature in [°C] as the abscissa. The bending angles indicate which plastic bending the specimen has undergone when fracture occurs.
  • the curve on the left shows a typical course of a brittle-ductile transition for a molybdenum-based alloy, as suggested as being particularly preferred for a high-temperature forming tool and a molybdenum content of > 99.0 wt .%, a boron "B” content of > 3 ppmw and a carbon "C” content of > 3 ppmw.
  • the base material of the high-temperature forming tool has a brittle-ductile transition temperature of ⁇ 60°C.
  • the brittle-ductile transition temperature defined by plastic bending with a bending angle of 20°, is even well below 60°C, namely around 30°C.
  • An auxiliary line is also entered at a bending angle of 20°.
  • a deflection of the specimen to a bending angle of 20° suffered in the event of fracture is used in the context of this application to determine the brittle-ductile transition temperature. If the plastic bending is > 20°, a ductile material behavior can be assumed for technological purposes.
  • the test parameters used in the three-point bending test were: a preload of 20 N [Newton], a test speed of 10 mm/min, a span of 20 mm.
  • the radius of the support rollers was 1.5 mm, as was the radius of the bending die.
  • the sample dimensions were 6 x 6 x 35 mm.
  • FIG. 8 shows a scanning electron micrograph of a molybdenum material according to the prior art.
  • the molybdenum material is in a recrystallized state.
  • the photograph shows a fracture surface of a tensile specimen tested at room temperature.
  • the presence of a so-called intergranular fracture is striking, i.e. a fracture with predominantly material separation along grain boundaries.
  • Such a detachment from grain boundaries is marked by the plotted arrow.
  • ductility is determined by the grain boundary strength.
  • FIG. 9 shows a fracture surface of a molybdenum-based alloy, as is suitable and preferably proposed for representing a hole dome according to the invention.
  • the alloying strategy is based on an improvement in grain boundary strength and is achieved in particular if the molybdenum base alloy has a molybdenum content of > 99.0% by weight, a boron content "B" of > 3 ppmw and a carbon content "C” of > 3 ppmw.
  • the fracture process here is transcrystalline, i.e. a fracture runs through the grains. This fracture can be attributed to a significantly increased grain boundary strength and is macroscopically associated with a significantly higher ductility.

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Abstract

L'invention concerne un outil de formage à haute température (1), l'outil de formage à haute température (1) étant constitué au moins en partie d'un alliage à base de molybdène présentant une teneur en molybdène ≥ 90 % en poids, l'alliage à base de molybdène étant présent dans un état fritté-comprimé et présentant à l'état fritté-comprimé une résistance aux chocs thermiques d'au moins 250 K, la résistance aux chocs thermiques étant définie en tant que quotient de ReH / (α·Ε), où ReH représente la limite d'élasticité à température ambiante en MPa, α est le coefficient de dilatation thermique en 1/k et E est le module d'élasticité en MPa.
EP21805347.8A 2020-11-13 2021-10-22 Outil de formage à haute température Pending EP4244473A1 (fr)

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ATGM50222/2020U AT17259U1 (de) 2020-11-13 2020-11-13 Hochtemperatur-umformwerkzeug
PCT/AT2021/060393 WO2022099329A1 (fr) 2020-11-13 2021-10-22 Outil de formage à haute température

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DE1073748B (de) * 1960-01-21 Westinghouse Electric Corporation, East Pittsburgh, Pa. (V. St. A.) Verwendung und Herstellung einer ausgehärteten Sinterlegierung
AT377584B (de) * 1981-06-25 1985-04-10 Klima & Kaelte Gmbh Eck-verbindung an metallrahmen
DE102005003445B4 (de) * 2005-01-21 2009-06-04 H.C. Starck Hermsdorf Gmbh Metallsubstrat-Werkstoff für die Anodenteller von Drehanodenröntgenröhren, Verfahren zur Herstellung eines solchen Werkstoffes sowie Verfahren zur Herstellung eines Anodentellers unter Verwendung eines solchen Werkstoffes
AT8697U1 (de) * 2005-10-14 2006-11-15 Plansee Se Rohrtarget
DE102007037736B4 (de) 2007-08-09 2012-11-15 Kocks Technik Gmbh & Co. Kg Dorn oder Dornstange für ein Rohrherstellungsverfahren und Verwendung solch eines Dorns oder solch einer Dornstange
AT15903U1 (de) * 2017-09-29 2018-08-15 Plansee Se Molybdän-Sinterteil
CN111020331B (zh) * 2019-12-18 2021-02-05 陕西斯瑞新材料股份有限公司 一种提高tzm棒材强度和塑性的方法

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AT17259U1 (de) 2021-10-15
CN116457559A (zh) 2023-07-18

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