CN114260329A - Ultra-low temperature extrusion forming method and device for high-entropy alloy thin-walled tube - Google Patents

Ultra-low temperature extrusion forming method and device for high-entropy alloy thin-walled tube Download PDF

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CN114260329A
CN114260329A CN202210154423.3A CN202210154423A CN114260329A CN 114260329 A CN114260329 A CN 114260329A CN 202210154423 A CN202210154423 A CN 202210154423A CN 114260329 A CN114260329 A CN 114260329A
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entropy alloy
extrusion
temperature
ultra
low temperature
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CN114260329B (en
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苑世剑
郑凯伦
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Dalian University of Technology
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Dalian University of Technology
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C23/00—Extruding metal; Impact extrusion
    • B21C23/02—Making uncoated products
    • B21C23/04—Making uncoated products by direct extrusion
    • B21C23/08—Making wire, bars, tubes
    • B21C23/085—Making tubes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C25/00—Profiling tools for metal extruding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C29/00—Cooling or heating work or parts of the extrusion press; Gas treatment of work
    • B21C29/003—Cooling or heating of work
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C31/00—Control devices, e.g. for regulating the pressing speed or temperature of metal; Measuring devices, e.g. for temperature of metal, combined with or specially adapted for use in connection with extrusion presses
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/08—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tubular bodies or pipes
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C30/00—Alloys containing less than 50% by weight of each constituent
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/02—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working in inert or controlled atmosphere or vacuum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/16—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of other metals or alloys based thereon

Abstract

The invention discloses an ultralow temperature extrusion forming method of a high-entropy alloy thin-walled tube, which utilizes a circulating cooling medium to form an ultralow temperature environment, ensures that a high-entropy alloy blank is continuously extruded and deformed in the ultralow temperature environment, utilizes the characteristic that the uniform elongation and hardening of a high-entropy alloy are improved simultaneously under the ultralow temperature condition, ensures the wall thickness uniformity and the surface quality of an extruded tube, ensures the internal accumulation of an intracrystalline substructure in the high-entropy alloy extruded tube, is matched with subsequent heat treatment to obtain the high-entropy alloy fine-grained tube, and solves the problems of uneven wall thickness and weakened tissue of the traditional hot extrusion. The invention also provides a high-entropy alloy thin-walled tube ultralow-temperature extrusion forming device which comprises an ultralow-temperature environment box, an extrusion rod, an extrusion cylinder, a prestress ring, a bottom plate and a temperature control cooling unit, wherein the temperature control cooling unit comprises a cooling medium source and a temperature measuring element, the extrusion cylinder, the prestress ring and the extrusion rod are all provided with cooling channels, and the cooling channels are communicated with the cooling medium source, so that the forming device can provide an ultralow-temperature environment for blanks.

Description

Ultra-low temperature extrusion forming method and device for high-entropy alloy thin-walled tube
Technical Field
The invention relates to the technical field of metal extrusion forming, in particular to a high-entropy alloy thin-walled tube ultralow-temperature extrusion forming method and device.
Background
The high-entropy alloy has the remarkable advantages of high strength, corrosion resistance, high temperature resistance and designability, has an extremely wide application temperature range, is a material frontier in recent years, and is expected to become a key material of high-end equipment components such as aerospace, ship navigation, weapons and the like. The thin-wall pipe is an ideal blank structure for forming an integral complex curved surface thin-wall part due to a closed geometric structure of the thin-wall pipe. Because the high-entropy alloy structure is complex to evolve and the performance is difficult to regulate, the existing pipe preparation technology such as hot rolling, hot extrusion, drawing, plate coil welding and the like cannot be used for preparing the high-entropy alloy thin-walled tube with excellent structure performance, uniform wall thickness, good surface quality and high reliability, and further cannot prepare a complex curved surface thin-walled component by plastically processing the high-entropy alloy thin-walled tube.
The hot extrusion is a common method for preparing a light-weight material pipe which is difficult to deform, and in order to obviously reduce the extrusion force, the blank is often heated to a temperature (0.6 times of the melting point of the alloy) higher than the recrystallization temperature; and when the temperature is higher, the material is softened seriously, so that the wall thickness of the extruded pipe is uneven.
The drawing process is a common process for preparing pipes and wires, and has the defects of limited drawing force, small single-pass deformation, frequent need of multi-pass deformation, long preparation period and high cost; the metal blank is subjected to tensile stress, surface cracks and even tensile fracture are easy to generate, and the method is not suitable for high-entropy alloy with obvious work hardening.
The reason that the plate roll welding is a low-cost preparation process for preparing the seamed pipe material and the method cannot be applied to the preparation of the high-entropy alloy pipe material is that: 1) the high-entropy alloy has large elastic modulus and high yield strength, so that the dimensional accuracy is low and the residual stress is large after the coil welding; 2) the roll welding of the high-entropy alloy pipe has a welding seam, but the existing welding process suitable for the high-entropy alloy is not reported, so that the welding quality cannot be ensured, and the reliability of the roll welding of the high-entropy alloy pipe is poor; 3) the roll-welded pipe blank cannot be used for manufacturing integral parts, and the reliability of components is difficult to guarantee due to welding seams.
Therefore, how to change the current situations that the wall thickness of a pipe fitting is uneven, the structure performance is poor, the surface quality is poor and the reliability is low when the high-entropy alloy thin-wall pipe is prepared in the prior art becomes a problem to be solved by the technical staff in the field.
Disclosure of Invention
The invention aims to provide a high-entropy alloy thin-walled tube ultralow-temperature extrusion forming method and device, which are used for solving the problems in the prior art, ensuring the wall thickness uniformity and surface quality of an extruded tube and improving the structure performance and reliability of the extruded tube.
In order to achieve the purpose, the invention provides the following scheme: the invention provides a high-entropy alloy thin-walled tube ultralow-temperature extrusion forming device which comprises an ultralow-temperature environment box, an extrusion rod, an extrusion cylinder, a prestress ring, a bottom plate and a temperature control cooling unit, wherein ultralow-temperature media can be contained in the ultralow-temperature environment box, the extrusion cylinder and the prestress ring are both arranged in the ultralow-temperature environment box, the prestress ring is sleeved outside the extrusion cylinder, the prestress ring is in interference fit with the extrusion cylinder, the extrusion rod and the extrusion cylinder are coaxially arranged, the extrusion rod can extend into the extrusion cylinder and can reciprocate along the axial direction of the extrusion cylinder, and high-entropy alloy blanks can be contained in the extrusion cylinder; the temperature control cooling unit comprises a cooling medium source and a temperature measuring element, the bottom plate is arranged at the bottom of the ultralow temperature environment box, the bottom plate is provided with a through hole allowing the extrusion rod to pass through, the extrusion cylinder is provided with a prestress ring and the extrusion rod are provided with cooling channels, and the cooling channels are communicated with the cooling medium source.
Preferably, the lateral wall of the ultra-low temperature environment box is provided with a heat insulation layer, and a heat insulation plate is arranged between the ultra-low temperature environment box and the bottom plate.
Preferably, the extrusion rod comprises a head part and a rod part which are connected, the high-entropy alloy blank is of a hollow columnar structure, the extrusion cylinder and the rod part are in clearance fit with the high-entropy alloy blank respectively, and the cooling channel is arranged in the head part.
Preferably, the outer diameter of the pre-stressed ring is 3-5 times the outer diameter of the container.
Preferably, the ultra-low temperature environment box, the prestressed ring and the extrusion container are all provided with temperature measuring channels, and the temperature measuring elements are arranged in the temperature measuring channels.
Preferably, the cooling channels are uniformly arranged conformal cooling water channels.
Preferably, the distance between the cooling channel in the extrusion cylinder and the forming surface of the extrusion cylinder is 2-5 mm.
The invention also provides an ultralow-temperature extrusion forming method of the high-entropy alloy thin-walled tube, which comprises the following steps of:
processing a high-entropy alloy block into a high-entropy alloy blank with a preset size, wherein an extrusion rod is in clearance fit with the inner wall of the high-entropy alloy blank, an extrusion cylinder is in clearance fit with the outer wall of the high-entropy alloy blank, the top surface of the high-entropy alloy blank is parallel to the bottom surface of the extrusion rod, and the high-entropy alloy blank is placed in an ultralow temperature environment box and cooled to an extrusion forming temperature;
secondly, placing the cooled high-entropy alloy blank into an extrusion container, wherein the temperature of an extrusion rod and the temperature of the extrusion container are not higher than that of the high-entropy alloy blank;
moving an extrusion rod, and returning the extrusion rod to remove tailings after extruding the high-entropy alloy pipe;
and step four, carrying out vacuum recrystallization annealing treatment on the extruded high-entropy alloy pipe to obtain the high-entropy alloy pipe with the fine-grained structure.
Preferably, in the first step, the cooling temperature range of the high-entropy alloy blank is-196 ℃ to-160 ℃.
Preferably, the high-entropy alloy blank is a basic Co-Cr-Fe-Ni-based high-entropy alloy, an aluminum element filled high-entropy alloy, a refractory high-entropy alloy or a light heat-resistant high-entropy alloy; the basic Co-Cr-Fe-Ni-based high-entropy alloy is a quaternary high-entropy or quinary high-entropy transition group element; the aluminum element added high-entropy alloy is one of Alx-Co-Cr-Fe-Ni; the refractory high-entropy alloy is one of refractory smelting elements added with Cr, Mo, V, Ta and Hf; the density of the light heat-resistant high-entropy alloy is less than 8.0kg/m3One of the use temperature is higher than 800 ℃;
the high-entropy alloy block is obtained by a smelting process or a powder metallurgy process, and the original casting defect is eliminated by carrying out vacuum homogenizing annealing or hot isostatic pressing treatment on the smelted blank; during vacuum homogenizing annealing treatment, the temperature range is 1000-1400 ℃, and the heat preservation time is 12-48 h; and during hot isostatic pressing treatment, the temperature range is 1000-1400 ℃, and the heat preservation time is 12-48 h.
The invention provides a high-entropy alloy thin-walled tube ultralow-temperature extrusion forming method, which comprises the following steps of:
preparing a high-entropy alloy block material, processing the prepared high-entropy alloy block into a high-entropy alloy blank with a preset size, and performing saponification and lubrication treatment on the surface of the high-entropy alloy blank;
secondly, placing the high-entropy alloy blank and the high-entropy alloy thin-wall tube ultralow-temperature extrusion forming device in an ultralow-temperature environment to be cooled to a low temperature, and continuously circulating a liquid nitrogen cooling medium in the high-entropy alloy thin-wall tube ultralow-temperature extrusion forming device; the temperature of the extrusion container, the temperature of the extrusion container and the temperature of the extrusion rod are not higher than the temperature of the high-entropy alloy blank;
placing the cooled high-entropy alloy blank into an extrusion container, wherein an extrusion rod is in clearance fit with the inner wall of the high-entropy alloy blank, the extrusion container is in clearance fit with the outer wall of the high-entropy alloy blank, and the top surface of the high-entropy alloy blank is parallel to the bottom surface of the extrusion rod;
driving an extrusion rod to move by a press, extruding the high-entropy alloy blank, and returning the extrusion rod to remove tailings after extruding the high-entropy alloy pipe;
and step five, carrying out vacuum recrystallization annealing treatment on the extruded high-entropy alloy pipe to obtain the high-entropy alloy pipe with the fine-grained structure.
Preferably, in the fourth step, the extrusion forming temperature range of the high-entropy alloy billet is-196 ℃ to-160 ℃, and a single-pass or multi-pass extrusion mode is adopted.
Preferably, in the fifth step, the temperature range of vacuum recrystallization annealing of the extruded high-entropy alloy pipe is 600-1000 ℃, and the heat preservation time is 12-48h, so that the high-entropy alloy pipe with the fine-grained structure is obtained.
The invention also provides a high-entropy alloy thin-walled tube ultralow-temperature extrusion forming device which comprises an extrusion cylinder, an extrusion rod, a sleeve, a prestress ring, a lower die holder and an upper die holder, wherein the extrusion cylinder can contain a high-entropy alloy blank, the extrusion cylinder is arranged on the lower die holder, the extrusion rod is connected with the upper die holder, the extrusion rod and the extrusion cylinder are coaxially arranged, the upper die holder can drive the extrusion rod to reciprocate along the axial direction of the extrusion cylinder, the extrusion rod can extend into the extrusion cylinder, the lower die holder is provided with a through hole through which the extrusion rod can pass, the side wall of the extrusion cylinder is provided with a cooling channel, the cooling channel can be communicated with an external cooling medium, and the extrusion cylinder is also connected with a temperature measuring element; the sleeve is sleeved outside the extrusion container, and the prestressed ring is sleeved outside the sleeve; one side of the lower die holder, which is close to the extrusion cylinder, is provided with a heat insulation plate, the extrusion cylinder, the sleeve and the prestress ring are all arranged on the heat insulation plate, and a heat insulation layer is sleeved outside the prestress ring.
Preferably, the lower die holder is arranged on a press platform, the upper die frame is arranged on the press upper platform, the upper die frame is slidably connected with the press upper platform, a guide pillar is further arranged between the press platform and the press upper platform, and the upper die frame is slidably sleeved outside the guide pillar; the external cooling medium is liquid nitrogen, the external cooling medium is connected with a liquid nitrogen circulating flow control element, the extrusion cylinder is connected with a control unit, and the liquid nitrogen circulating flow control element and the temperature measuring element are respectively connected with the control unit.
Compared with the prior art, the invention has the following technical effects: the invention provides a high-entropy alloy thin-walled tube ultralow-temperature extrusion forming device which comprises an ultralow-temperature environment box, an extrusion rod, an extrusion container, a prestress ring, a bottom plate and a temperature control cooling unit, wherein ultralow-temperature media can be contained in the ultralow-temperature environment box, the extrusion container and the prestress ring are both arranged in the ultralow-temperature environment box, the prestress ring is sleeved outside the extrusion container, the prestress ring is in interference fit with the extrusion container, the extrusion rod and the extrusion container are coaxially arranged, the extrusion rod can extend into the extrusion container and can reciprocate along the axial direction of the extrusion container, and high-entropy alloy blanks can be contained in the extrusion container; the temperature control cooling unit comprises a cooling medium source and a temperature measuring element, the bottom plate is arranged at the bottom of the ultra-low temperature environment box and provided with a through hole through which the extrusion rod can pass, the extrusion cylinder, the prestress ring and the extrusion rod are all provided with cooling channels, and the cooling channels are communicated with the cooling medium source.
According to the ultra-low temperature extrusion forming device for the high-entropy alloy thin-walled tube, the extrusion forming of the extrusion die device and the high-entropy alloy blank is ensured under the ultra-low temperature condition through the combined action of the circulating cooling medium inside the extrusion die and the external ultra-low temperature environment box, and the temperature rise of the blank caused by extrusion deformation heat is avoided.
The invention also provides an ultralow temperature extrusion forming method of the high-entropy alloy thin-walled tube, which utilizes the forming device and adopts an ultralow temperature part with a circulating cooling medium to ensure that a high-entropy alloy blank deforms under an ultralow temperature environment, utilizes the characteristic that the uniform elongation and hardening of the high-entropy alloy are improved simultaneously under the ultralow temperature condition to ensure the wall thickness uniformity and surface quality of an extruded tube, ensures the accumulation of an intracrystalline substructure inside the high-entropy alloy extruded tube, and is matched with subsequent heat treatment to obtain the high-entropy alloy fine-grained tube, thereby solving the problems of serious oxidation, weakened structural performance and uneven wall thickness of the traditional hot-extruded high-entropy alloy. The obtained pipe has no welding seam, high size precision and high reliability.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is a schematic structural diagram of the ultra-low temperature extrusion forming device for the high-entropy alloy thin-walled tube of the invention;
FIG. 2 is a flow chart of the ultra-low temperature extrusion forming method of the high-entropy alloy thin-walled tube of the invention;
FIG. 3 is a schematic diagram of an extrusion state of the ultra-low temperature extrusion forming method of the high-entropy alloy thin-walled tube of the invention;
FIG. 4 is a schematic heat treatment diagram of the high-entropy alloy thin-walled tube obtained by the ultra-low temperature extrusion forming method for the high-entropy alloy thin-walled tube;
FIG. 5 is a schematic diagram of an extrusion state in a third embodiment and a fourth embodiment of the ultralow-temperature extrusion forming method of the high-entropy alloy thin-walled tube;
FIG. 6 is a schematic structural diagram of a third embodiment and a fourth embodiment of the ultra-low temperature extrusion forming device for the high-entropy alloy thin-walled tube of the invention;
the device comprises a base plate, a heat insulation plate, a temperature control cooling unit, a cooling channel, a high-entropy alloy blank, a heat insulation plate, a high-entropy alloy blank, a high-temperature environment box, a high-entropy alloy blank, a low-temperature environment box, a high-temperature, a low-temperature, and a high-temperature-low-temperature;
001 is an extrusion cylinder, 002 is a sleeve, 003 is a prestressed ring, 004 is a lower die holder, 005 is an upper die frame, 006 is a high-entropy alloy blank, 007 is a cooling channel, 008 is an external cooling medium, 009 is a temperature measuring element, 010 is a heat insulating plate, 011 is a heat insulating layer, 012 is a press platform, 013 is an upper press platform, 014 is a guide pillar, 015 is a liquid nitrogen circulation flow control element, 016 is a control unit, and 017 is an extrusion rod.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention aims to provide a high-entropy alloy thin-walled tube ultralow-temperature extrusion forming method and device, which are used for solving the problems in the prior art, ensuring the wall thickness uniformity and surface quality of an extruded tube and improving the structure performance and reliability of the extruded tube.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Referring to fig. 1 to 5, wherein fig. 1 is a schematic structural diagram of a high-entropy alloy thin-walled tube ultra-low temperature extrusion molding device of the present invention, fig. 2 is a flowchart of a high-entropy alloy thin-walled tube ultra-low temperature extrusion molding method of the present invention, fig. 3 is a schematic extrusion state diagram of a high-entropy alloy thin-walled tube ultra-low temperature extrusion molding method of the present invention, fig. 4 is a schematic thermal treatment diagram of a high-entropy alloy thin-walled tube obtained by the high-entropy alloy thin-walled tube ultra-low temperature extrusion molding method of the present invention, fig. 5 is a schematic extrusion state diagram of a third embodiment and a fourth embodiment of the high-entropy alloy thin-walled tube ultra-low temperature extrusion molding method of the present invention, and fig. 6 is a schematic structural diagram of a third embodiment and a fourth embodiment of the high-entropy alloy thin-walled tube ultra-low temperature extrusion molding device of the present invention.
The invention provides a high-entropy alloy thin-walled tube ultralow-temperature extrusion forming device, which comprises an ultralow-temperature environment box 1, an extrusion rod 2, an extrusion cylinder 3, a prestress ring 4, a bottom plate 5 and a temperature control cooling unit 7, wherein ultralow-temperature media can be contained in the ultralow-temperature environment box 1, the extrusion cylinder 3 and the prestress ring 4 are both arranged in the ultralow-temperature environment box 1, the prestress ring 4 is sleeved outside the extrusion cylinder 3, the prestress ring 4 is in interference fit with the extrusion cylinder 3, the extrusion rod 2 and the extrusion cylinder 3 are coaxially arranged, the extrusion rod 2 can extend into the extrusion cylinder 3 and can reciprocate along the axial direction of the extrusion cylinder 3, and a high-entropy alloy blank 9 can be contained in the extrusion cylinder 3; the temperature control cooling unit 7 comprises a cooling medium source and a temperature measuring element, the bottom plate 5 is arranged at the bottom of the ultra-low temperature environment box 1, the bottom plate 5 is provided with a through hole which can allow the extrusion rod 2 to pass through, the extrusion container 3, the prestress ring 4 and the extrusion rod 2 are all provided with a cooling channel 8, and the cooling channel 8 is communicated with the cooling medium source.
When the ultra-low temperature extrusion forming device of the high-entropy alloy thin-walled tube is utilized, the ultra-low temperature environment box 1 can cool the high-entropy alloy blank 9, the extrusion cylinder 3 and the pre-stress ring 4 are all arranged in the ultra-low temperature environment box 1, meanwhile, the extrusion rod 2, the extrusion cylinder 3 and the pre-stress ring 4 are all provided with the cooling channel 8, a cooling medium source is communicated with the cooling channel 8, the ultra-low temperature medium circularly flows in the cooling channel 8, the temperature of a component and the high-entropy alloy blank 9 in the forming process can be reduced, so that the high-entropy alloy blank 9 is ensured to be continuously extruded and deformed in the ultra-low temperature environment, the characteristics of the uniform elongation and the hardening of the high-entropy alloy under the ultra-low temperature condition are utilized, the wall thickness uniformity and the surface quality of the extruded tube are ensured, meanwhile, the intracrystalline substructure accumulated in the high-entropy alloy extruded tube is ensured, and the high-entropy alloy tube is obtained by matching with the subsequent heat treatment, solves the problem of weakening the traditional hot extrusion tissue. The obtained pipe has no welding seam, high size precision and high reliability. In practical application, the ultralow temperature medium can adopt liquid nitrogen or liquid helium, and in order to ensure that the ultralow temperature medium can smoothly circulate in the cooling channel 8, a pump body can be arranged, so that the flow of the ultralow temperature medium can be controlled while the ultralow temperature medium smoothly circulates, and the flow of the ultralow temperature medium is 0.1-1L/s.
It should be noted that the prestressed ring 4 and the extrusion container 3 are assembled by a shrink fit to realize interference fit, and the inner diameter of the prestressed ring 4 and the outer diameter of the extrusion container 3 have a specific interference magnitude, so as to ensure that the extrusion container 3 is in a circumferential compressive stress state; the prestressed ring 4 is made of a high-toughness mould material without cold brittleness.
In order to reduce the heat exchange between the ultra-low temperature environment box 1 and the external environment, the side wall of the ultra-low temperature environment box 1 is provided with a heat insulation layer which is made of heat insulation materials, a heat insulation plate 6 is arranged between the ultra-low temperature environment box 1 and the bottom plate 5, the heat exchange is reduced, and the low temperature environment condition of the extrusion device is ensured.
Wherein the extrusion stem 2 comprises a head portion and a stem portion connected, and the cooling channel 8 is provided in the head portion. The extrusion rod 2 and the extrusion cylinder 3 are both made of hard alloy die materials without cold brittleness, and particularly tungsten steel, high-speed tool steel or cold-work die steel can be selected.
The high-entropy alloy blank 9 is a hollow columnar structure, namely a thick-wall ring structure, the extrusion container 3 and the rod part are in clearance fit with the high-entropy alloy blank 9 respectively, the outer diameter of the prestress ring 4 is 3-5 times of the outer diameter of the extrusion container 3, the extrusion ratio can be 3-10, and the wall thickness of the extrusion pipe is 1-3 mm.
Specifically, the ultra-low temperature environment box 1, the pre-stress ring 4 and the extrusion container 3 are all provided with temperature measuring channels, the temperature measuring elements are arranged in the temperature measuring channels, the temperature measuring elements can select thermocouples and can monitor the cooling temperature of the high-entropy alloy blank 9 and the temperature of the environment in the forming process of the high-entropy alloy blank 9 in real time, so that the temperature and the flow of an ultra-low temperature medium can be controlled according to the temperature, and a forming temperature field is guaranteed.
In addition, the cooling channel 8 is a conformal cooling water channel which is uniformly arranged, so that the flowing uniformity of the ultralow-temperature medium is improved, and the uniform cooling of all parts can be ensured.
More specifically, the distance between the cooling channel 8 in the extrusion container 3 and the forming surface of the extrusion container 3 is 2-5mm, and the extrusion deformation of the high-entropy alloy blank 9 in the ultralow-temperature environment is guaranteed on the premise of not losing strength.
The invention also provides an ultralow-temperature extrusion forming method of the high-entropy alloy thin-walled tube, which comprises the following steps of:
firstly, processing a high-entropy alloy block into a high-entropy alloy blank 9 with a preset size, enabling an extrusion rod 2 to be in clearance fit with the inner wall of the high-entropy alloy blank 9, enabling an extrusion container 3 to be in clearance fit with the outer wall of the high-entropy alloy blank 9, enabling the top surface of the high-entropy alloy blank 9 to be parallel to the bottom surface of the extrusion rod 2, and placing the high-entropy alloy blank 9 in an ultralow-temperature environment box 1 to be cooled to an extrusion forming temperature;
secondly, placing the cooled high-entropy alloy blank 9 into an extrusion container 3, wherein the temperature of the extrusion rod 2 and the temperature of the extrusion container 3 are not higher than that of the high-entropy alloy blank 9;
moving the extrusion rod 2, after extruding the high-entropy alloy pipe, returning the extrusion rod 2, replacing a part for cutting, and removing tailings;
and step four, carrying out vacuum recrystallization annealing treatment on the extruded high-entropy alloy pipe, wherein the temperature range is 600-1000 ℃, and the heat preservation time is 12-48h to obtain the high-entropy alloy pipe with the fine grain structure.
It is emphasized that in the first step, the cooling temperature range of the high-entropy alloy billet 9 is-196 ℃ to-160 ℃.
Further, the high-entropy alloy billet 9 is a basic Co-Cr-Fe-Ni-based high-entropy alloy, an aluminum element filled high-entropy alloy, a refractory high-entropy alloy or a light heat-resistant high-entropy alloy; the basic Co-Cr-Fe-Ni-based high-entropy alloy is a quaternary high-entropy or quinary high-entropy transition group element; the aluminum element added high-entropy alloy is one of Alx-Co-Cr-Fe-Ni; the refractory high-entropy alloy is one of refractory smelting elements added with Cr, Mo, V, Ta and Hf; the density of the light heat-resistant high-entropy alloy is less than 8.0kg/m3And a use temperature of more than 800 ℃.
The high-entropy alloy block is obtained by a smelting process or a powder metallurgy process, and the original casting defect is eliminated by carrying out vacuum homogenizing annealing or hot isostatic pressing treatment on the smelted blank; during vacuum homogenizing annealing treatment, the temperature range is 1000-1400 ℃, and the heat preservation time is 12-48 h; and during hot isostatic pressing treatment, the temperature range is 1000-1400 ℃, and the heat preservation time is 12-48 h.
The ultra-low temperature extrusion forming method of the high-entropy alloy thin-walled tube of the present invention is further explained by the following specific examples.
Example one
Step 101: preparing a high-entropy alloy block according to preset parameters; the high-entropy alloy blank 9 is one of a basic high-entropy alloy (Co-Cr-Fe-Ni base), an aluminum element filled high-entropy alloy, a refractory high-entropy alloy and a light heat-resistant high-entropy alloy. The preset parameters comprise melting parameters, hot isostatic pressing parameters and homogenizing annealing parameters of the high-entropy alloy billet 9. And obtaining the high-entropy alloy blank 9 by using mechanical processing.
The preparation method of the high-entropy alloy block is one of vacuum induction melting and powder metallurgy. The diameter of the high-entropy alloy block is 20-200mm, and the height of the high-entropy alloy block is 20-200 mm. When the high-entropy alloy block is CoFeMnNi, the hot isostatic pressing parameter is 1100-; the homogenization annealing parameter is 1100-1300 ℃, and the heat preservation time is 12-48 h;
after mechanical processing, the inner diameter of the high-entropy alloy blank 9 is the same as the outer diameter of the extrusion rod 2, and the inner diameter and the outer diameter are in clearance fit; the outer diameter of the high-entropy alloy blank 9 is the same as the inner diameter of the extrusion container 3, and the high-entropy alloy blank is in clearance fit with the extrusion container; the height of the high-entropy alloy billet 9 is lower than that of the extrusion container 3.
Step 102: and (3) cooling the high-entropy alloy blank 9 in an ultralow-temperature environment box 1, wherein the preset extrusion forming temperature range is-196 ℃ to-160 ℃.
Step 103: placing the cooled high-entropy alloy blank 9 into an extrusion container 3; liquid nitrogen circularly flows among the extrusion rod 2, the extrusion cylinder 3 and the prestressed ring 4; the temperature of the extrusion rod 2 and the extrusion container 3 is not higher than that of the high-entropy alloy blank 9.
Step 104: the extrusion rod 2 descends at a certain speed to perform extrusion. The extrusion speed is 2-20 mm/s.
Under the cooling effect of liquid nitrogen in the extrusion process, the temperature control cooling unit 7 feeds back temperature parameters through a thermocouple to adjust the flow of the liquid nitrogen, and the extrusion rod 2, the extrusion cylinder 3 and the prestressed ring 4 are ensured to be extruded within the temperature range of-196 ℃ to-160 ℃. FIG. 3 is a schematic view of the extrusion state of the ultra-low temperature extrusion of the high-entropy alloy thin-walled tube in this embodiment.
Step 105: and (3) returning the extrusion rod 2, replacing the extrusion rod 2 with a discharge rod, descending the discharge rod, and cutting off materials to obtain the extruded high-entropy alloy thin-walled tube.
Step 106: and carrying out vacuum homogenization annealing treatment on the extruded high-entropy alloy thin-walled tube to obtain the high-entropy alloy thin-walled tube with the fine-grained structure. As shown in fig. 4.
Example two
The high-entropy alloy blank 9 is a CoFeMnNi quaternary high-entropy alloy. The extrusion rod 2 and the extrusion cylinder 3 are made of D2 cold-work die steel, and subjected to surface nitriding treatment, grinding and polishing. The material of the prestressed ring 4 is 316L stainless steel. The outer diameter of the high-entropy alloy blank 9 is 40mm, the inner diameter is 25mm, the height is 50mm, the material is cooled to-160 ℃, the temperature control state of the die is an isothermal state, and the temperature of the die is the same as the critical temperature. The hardening capacity and the uniform elongation of the high-entropy alloy blank 9 are improved under the ultralow temperature condition, and the blank is extruded and formed by a die which is also under the ultralow temperature condition, so that the defect of temperature rise of the blank in the extrusion process is overcome. The method comprises the following specific steps:
and determining the preparation process and the heat treatment system of the high-entropy alloy block according to the type of the high-entropy alloy material to be extruded. Preparing a high-entropy alloy block by adopting a vacuum induction melting mode, performing hot isostatic pressing treatment under the pressure conditions of 1200 ℃ multiplied by 24h and 200MPa, performing vacuum homogenization annealing treatment for 1100 ℃ multiplied by 24h, and machining the obtained high-entropy alloy block to a target size.
Cooling the high-entropy alloy blank 9 to a preset extrusion forming temperature in an ultralow temperature environment, wherein the extrusion forming temperature of CoFeMnNi is preset to be-160 ℃; placing the high-entropy alloy blank 9 into the extrusion container 3, and simultaneously enabling a circulating liquid nitrogen medium to flow inside the extrusion rod 2, the extrusion container 3 and the prestressed ring 4 to ensure that the temperature of an extrusion die is not higher than that of the high-entropy alloy blank 9; and carrying out ultralow-temperature extrusion in a near isothermal die temperature field, wherein in the extrusion process, the liquid nitrogen medium continuously circulates, and the temperature rise in the extrusion process of the high-entropy alloy blank 9 is reduced.
After the high-entropy alloy thin-walled tube is extruded, the extrusion rod 2 returns to replace the discharge rod, and the unextruded tailings are cut off.
The invention provides an ultralow temperature extrusion forming method and device for a high-entropy alloy thin-walled tube, which adopts an ultralow temperature medium to ensure that a high-entropy alloy blank 9 is continuously extruded and deformed in an ultralow temperature environment, utilizes the characteristic that the uniform elongation and hardening of the high-entropy alloy are improved simultaneously under the ultralow temperature condition to ensure the wall thickness uniformity and surface quality of an extruded tube, ensures the accumulation of an intracrystalline substructure inside the high-entropy alloy extruded tube, is matched with subsequent heat treatment to obtain the high-entropy alloy fine-grained tube, and solves the problem of the weakening of the traditional hot extrusion structure. The obtained pipe has no welding seam, high size precision and high reliability.
The invention provides a high-entropy alloy thin-walled tube ultralow-temperature extrusion forming method, which comprises the following steps of:
step one, preparing a high-entropy alloy block material, processing the prepared high-entropy alloy block into a high-entropy alloy blank 006 with a preset size, and extruding the surface of the blank to perform lubrication treatment such as saponification;
and step two, placing the high-entropy alloy blank 006 and the extrusion die in an ultralow-temperature environment to be cooled to a low temperature, and continuously circulating a liquid nitrogen cooling medium in the extrusion die. In the extrusion container 001, the temperature of the extrusion rod 017 and the extrusion container 001 is not higher than that of the high-entropy alloy blank 006;
step three, placing the cooled high-entropy alloy blank 006 into an extrusion cylinder 001, wherein the extrusion rod 017 is in clearance fit with the inner wall of the high-entropy alloy blank 006, the extrusion cylinder 001 is in clearance fit with the outer wall of the high-entropy alloy blank 006, and the top surface of the high-entropy alloy blank 006 is parallel to the bottom surface of the extrusion rod 017;
step four, the press drives the extrusion rod 017 to move, the high-entropy alloy blank 006 is extruded in a single-pass or multi-pass mode, after the high-entropy alloy pipe is extruded, the extrusion rod 017 returns, and tailings are removed;
and step five, carrying out vacuum recrystallization annealing treatment on the extruded high-entropy alloy pipe to obtain the high-entropy alloy pipe with the fine-grained structure.
In the fourth step, the extrusion forming temperature range of the high-entropy alloy blank is-196 ℃ to-160 ℃, and a single-pass or multi-pass extrusion mode is adopted.
And fifthly, carrying out vacuum recrystallization annealing on the extruded high-entropy alloy pipe at the temperature range of 600-1000 ℃ for 12-48h to obtain the high-entropy alloy pipe with the fine-grained structure.
Further, the high-entropy alloy billet 006 is a basic Co-Cr-Fe-Ni-based high-entropy alloy, an aluminum element filled high-entropy alloy, a refractory high-entropy alloy or a light heat-resistant high-entropy alloy; the basic Co-Cr-Fe-Ni-based high-entropy alloy is a quaternary high-entropy or quinary high-entropy transition group element; the high-entropy alloy added with the aluminum element is Alx-Co-One of Cr-Fe-Ni; the refractory high-entropy alloy is one of refractory smelting elements added with Cr, Mo, V, Ta and Hf; the density of the light heat-resistant high-entropy alloy is less than 8.0kg/m3And a use temperature of more than 800 ℃.
The high-entropy alloy block is obtained by a smelting process or a powder metallurgy process, and the original casting defect is eliminated by carrying out vacuum homogenizing annealing or hot isostatic pressing treatment on the smelted blank; during vacuum homogenizing annealing treatment, the temperature range is 1000-1400 ℃, and the heat preservation time is 12-48 h; and during hot isostatic pressing treatment, the temperature range is 1000-1400 ℃, and the heat preservation time is 12-48 h.
EXAMPLE III
Step 101: preparing a high-entropy alloy block according to preset parameters; the high-entropy alloy billet 006 is one of a basic high-entropy alloy (Co-Cr-Fe-Ni base), an aluminum element filled high-entropy alloy, a refractory high-entropy alloy and a light heat-resistant high-entropy alloy. The preset parameters comprise melting parameters, hot isostatic pressing parameters and homogenizing annealing parameters of the high-entropy alloy billet 006. And obtaining the high-entropy alloy billet 006 by machining.
The preparation method of the high-entropy alloy block is one of vacuum induction melting and powder metallurgy. The diameter of the high-entropy alloy block is 20-200mm, and the height of the high-entropy alloy block is 20-200 mm. When the high-entropy alloy block is CoFeMnNi, the hot isostatic pressing parameter is 1100-; the homogenization annealing parameter is 1100-1300 ℃, and the heat preservation time is 12-48 h;
after mechanical processing, the inner diameter of the high-entropy alloy blank 006 is the same as the outer diameter of the extrusion rod 017, and the inner diameter and the outer diameter are in clearance fit; the outer diameter of the high-entropy alloy billet 006 is the same as the inner diameter of the extrusion container 001, and the outer diameter and the inner diameter are in clearance fit; the height of the high-entropy alloy billet 006 is lower than the height of the extrusion container 001.
And after mechanical processing, the surface of the high-entropy alloy blank is subjected to lubricating treatment such as saponification and phosphorization.
Step 102: and (3) cooling the high-entropy alloy blank 006 and the extrusion die in an ultralow temperature environment, wherein the preset extrusion forming temperature range is-196 ℃ to-160 ℃.
Step 103: placing the cooled high-entropy alloy billet 006 in a container 001; liquid nitrogen circularly flows among the extrusion rod 017, the extrusion cylinder 001 and the prestress ring 003; the temperature of the extrusion rod 017 and the extrusion cylinder 001 is not higher than that of the high-entropy alloy blank 006.
Step 104: the extrusion rod 017 descends at a certain speed to extrude the blank in a single way/multiple ways. The extrusion speed is 2-20 mm/s.
Under the cooling effect of liquid nitrogen in the extrusion process, the control unit 016 feeds back temperature parameters through the thermocouples to adjust the flow of the liquid nitrogen, so that the extrusion rod 017, the extrusion cylinder 001 and the prestressed ring 003 are extruded within a temperature range of-196 ℃ to-160 ℃.
Step 105: and returning the extrusion rod 017, replacing the extrusion rod 017 with a discharging rod, descending the discharging rod, and cutting off the material to obtain the extruded high-entropy alloy thin-walled tube.
Step 106: and carrying out vacuum homogenization annealing treatment on the extruded high-entropy alloy thin-walled tube to obtain the high-entropy alloy thin-walled tube with the fine-grained structure.
Example four
The high-entropy alloy billet 006 is a CoFeMnNi quaternary high-entropy alloy, and the surface of the high-entropy alloy billet is subjected to saponification treatment. The extrusion rod 017 and the extrusion cylinder 001 are made of D2 cold-work die steel, and subjected to surface nitriding treatment and grinding and polishing. The material of the prestressed ring 003 is 316L stainless steel. The outer diameter of the high-entropy alloy blank 006 is 40mm, the inner diameter is 25mm, the height is 50mm, the material is cooled to-160 ℃, the temperature control state of the die is an isothermal state, and the temperature of the die is the same as the critical temperature. The hardening capacity and the uniform elongation of the high-entropy alloy blank 006 are improved under the ultralow temperature condition, and the blank is extruded and formed through a die which is also under the ultralow temperature condition, so that the defect of temperature rise of the blank in the extrusion process is overcome. The method comprises the following specific steps:
and determining the preparation process and the heat treatment system of the high-entropy alloy block according to the type of the high-entropy alloy material to be extruded. Preparing a high-entropy alloy block by adopting a vacuum induction melting mode, performing hot isostatic pressing treatment under the pressure conditions of 1200 ℃ multiplied by 24h and 200MPa, performing vacuum homogenization annealing treatment for 1100 ℃ multiplied by 24h, and machining the obtained high-entropy alloy block to a target size.
Cooling the high-entropy alloy blank 006 to a preset extrusion forming temperature in an ultralow temperature environment, wherein the extrusion forming temperature of CoFeMnNi is preset to be-160 ℃; the high-entropy alloy blank 006 is placed in an extrusion cylinder 001, and a circulating liquid nitrogen medium flows in an extrusion rod 017, the extrusion cylinder 001 and a prestress ring 003 to ensure that the temperature of an extrusion die is not higher than that of the high-entropy alloy blank 006; and carrying out ultralow-temperature extrusion in a temperature field of the near-isothermal die, wherein in the extrusion process, the liquid nitrogen medium continuously circulates, and the temperature rise in the extrusion process of the high-entropy alloy blank 006 is reduced.
After the high-entropy alloy thin-walled tube is extruded, the extrusion rod 017 returns to replace the discharge rod, and the unextruded tailings are cut off.
The invention also provides a high-entropy alloy thin-walled tube ultralow-temperature extrusion forming device, which comprises an extrusion cylinder 001, an extrusion rod 017, a sleeve 002, a prestressed ring 003, a lower die holder 004 and an upper die holder 005, wherein the extrusion cylinder 001 can contain a high-entropy alloy blank 006, the extrusion cylinder 001 is arranged on the lower die holder 004, the extrusion rod 017 is connected with the upper die holder 005, the extrusion rod 017 and the extrusion cylinder 001 are coaxially arranged, the upper die holder 005 can drive the extrusion rod 017 to reciprocate along the axial direction of the extrusion cylinder 001, the extrusion rod 017 can extend into the extrusion cylinder 001, the lower die holder 004 is provided with a through hole through which the extrusion rod 017 can pass, the side wall of the extrusion cylinder 001 is provided with a cooling channel 007, the cooling channel 007 can be communicated with an external cooling medium 008, and the extrusion cylinder 001 is also connected with a temperature measuring element 009; the sleeve 002 is sleeved outside the extrusion container 001, and the prestressed ring 003 is sleeved outside the sleeve 002; one side that the die holder 004 is close to recipient 001 sets up heat insulating board 010, and recipient 001, sleeve 002 and prestressing force ring 003 all set up on heat insulating board 010, and prestressing force ring 003 outside cover is equipped with insulating layer 011, reduces the heat exchange of operating region and external environment.
The lower die holder 004 is arranged on a press platform 012, the upper die carrier 005 is arranged on a press upper platform 013, the upper die carrier 005 is slidably connected with the press upper platform 013, a guide pillar 014 is further arranged between the press platform 012 and the press upper platform 013, the upper die carrier 005 is slidably sleeved outside the guide pillar 014, and the guide pillar 014 provides guidance for the reciprocating motion of the upper die carrier 005; in this embodiment, the external cooling medium 008 is liquid nitrogen, the external cooling medium 008 is connected to a liquid nitrogen circulation flow rate control element 015, the container 001 is connected to the control unit 016, and the liquid nitrogen circulation flow rate control element 015 and the temperature measurement element 009 are both connected to the control unit 016 respectively.
According to the ultralow-temperature extrusion forming device and method for the high-entropy alloy thin-wall tube, the ultralow-temperature medium is adopted to ensure that the high-entropy alloy blank 006 is continuously extruded and deformed in the ultralow-temperature environment, the characteristics that the uniform elongation and hardening of the high-entropy alloy are improved at the same time under the ultralow-temperature condition are utilized, the wall thickness uniformity and the surface quality of the extruded tube are ensured, the intra-crystalline substructure accumulated in the high-entropy alloy extruded tube is ensured, the subsequent heat treatment is matched to obtain the high-entropy alloy fine-grain tube, and the problem of weakening of the traditional hot extrusion structure is solved. The obtained pipe has no welding seam, high size precision and high reliability.
The principle and the implementation mode of the invention are explained by applying a specific example, and the description of the embodiment is only used for helping to understand the method and the core idea of the invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.

Claims (15)

1. The utility model provides a high entropy alloy thin wall pipe ultra-low temperature extrusion forming device which characterized in that: the ultra-low temperature medium container comprises an ultra-low temperature environment box, an extrusion rod, an extrusion container, a prestress ring, a bottom plate and a temperature control cooling unit, wherein an ultra-low temperature medium can be contained in the ultra-low temperature environment box, the extrusion container and the prestress ring are arranged in the ultra-low temperature environment box, the prestress ring is sleeved outside the extrusion container, the prestress ring is in interference fit with the extrusion container, the extrusion rod and the extrusion container are coaxially arranged, the extrusion rod can extend into the extrusion container and can reciprocate along the axis direction of the extrusion container, and a high-entropy alloy blank can be contained in the extrusion container; the temperature control cooling unit comprises a cooling medium source and a temperature measuring element, the bottom plate is arranged at the bottom of the ultralow temperature environment box, the bottom plate is provided with a through hole allowing the extrusion rod to pass through, the extrusion cylinder is provided with a prestress ring and the extrusion rod are provided with cooling channels, and the cooling channels are communicated with the cooling medium source.
2. The ultra-low temperature extrusion forming device for the high-entropy alloy thin-walled tube according to claim 1, characterized in that: the lateral wall of the ultra-low temperature environment box is provided with a heat preservation and insulation layer, and a heat insulation plate is arranged between the ultra-low temperature environment box and the bottom plate.
3. The ultra-low temperature extrusion forming device for the high-entropy alloy thin-walled tube according to claim 1, characterized in that: the extrusion rod comprises a head part and a rod part which are connected, the high-entropy alloy blank is of a hollow columnar structure, the extrusion cylinder and the rod part are in clearance fit with the high-entropy alloy blank respectively, and the cooling channel is arranged in the head part.
4. The ultra-low temperature extrusion forming device for the high-entropy alloy thin-walled tube according to claim 1, characterized in that: the outer diameter of the prestressed ring is 3-5 times of the outer diameter of the extrusion container.
5. The ultra-low temperature extrusion forming device for the high-entropy alloy thin-walled tube according to claim 1, characterized in that: the ultra-low temperature environment case the prestressing force ring with the recipient all sets up the temperature measurement passageway, temperature element set up in the temperature measurement passageway.
6. The ultra-low temperature extrusion forming device for the high-entropy alloy thin-walled tube according to claim 1, characterized in that: the cooling channels are uniformly arranged conformal cooling water channels.
7. The ultra-low temperature extrusion forming device for the high-entropy alloy thin-walled tube according to claim 1, characterized in that: the distance between the cooling channel in the extrusion container and the forming surface of the extrusion container is 2-5 mm.
8. An ultralow-temperature extrusion forming method for a high-entropy alloy thin-walled tube, which utilizes the ultralow-temperature extrusion forming device for the high-entropy alloy thin-walled tube, which is characterized by comprising the following steps of:
processing a high-entropy alloy block into a high-entropy alloy blank with a preset size, wherein an extrusion rod is in clearance fit with the inner wall of the high-entropy alloy blank, an extrusion cylinder is in clearance fit with the outer wall of the high-entropy alloy blank, the top surface of the high-entropy alloy blank is parallel to the bottom surface of the extrusion rod, and the high-entropy alloy blank is placed in an ultralow temperature environment box and cooled to an extrusion forming temperature;
secondly, placing the cooled high-entropy alloy blank into an extrusion container, wherein the temperature of an extrusion rod and the temperature of the extrusion container are not higher than that of the high-entropy alloy blank;
moving an extrusion rod, and returning the extrusion rod to remove tailings after extruding the high-entropy alloy pipe;
and step four, carrying out vacuum recrystallization annealing treatment on the extruded high-entropy alloy pipe to obtain the high-entropy alloy pipe with the fine-grained structure.
9. The ultra-low temperature extrusion forming method for the high-entropy alloy thin-walled tube according to claim 8, characterized in that: in the first step, the cooling temperature range of the high-entropy alloy blank is-196 ℃ to-160 ℃.
10. The ultra-low temperature extrusion forming method for the high-entropy alloy thin-walled tube according to claim 8, characterized in that: the high-entropy alloy blank is a basic Co-Cr-Fe-Ni-based high-entropy alloy, an aluminum element filled high-entropy alloy, a refractory high-entropy alloy or a light heat-resistant high-entropy alloy; the basic Co-Cr-Fe-Ni-based high-entropy alloy is a quaternary high-entropy or quinary high-entropy transition group element; the aluminum element added high-entropy alloy is one of Alx-Co-Cr-Fe-Ni; the refractory high-entropy alloy is one of refractory smelting elements added with Cr, Mo, V, Ta and Hf; the density of the light heat-resistant high-entropy alloy is less than 8.0kg/m3One of the use temperature is higher than 800 ℃;
the high-entropy alloy block is obtained by a smelting process or a powder metallurgy process, and the original casting defect is eliminated by carrying out vacuum homogenizing annealing or hot isostatic pressing treatment on the smelted blank; during vacuum homogenizing annealing treatment, the temperature range is 1000-1400 ℃, and the heat preservation time is 12-48 h; and during hot isostatic pressing treatment, the temperature range is 1000-1400 ℃, and the heat preservation time is 12-48 h.
11. An ultra-low temperature extrusion forming method of a high-entropy alloy thin-walled tube is characterized by comprising the following steps:
preparing a high-entropy alloy block material, processing the prepared high-entropy alloy block into a high-entropy alloy blank with a preset size, and performing saponification and lubrication treatment on the surface of the high-entropy alloy blank;
secondly, placing the high-entropy alloy blank and the high-entropy alloy thin-wall tube ultralow-temperature extrusion forming device in an ultralow-temperature environment to be cooled to a low temperature, and continuously circulating a liquid nitrogen cooling medium in the high-entropy alloy thin-wall tube ultralow-temperature extrusion forming device; the temperature of the extrusion container, the temperature of the extrusion container and the temperature of the extrusion rod are not higher than the temperature of the high-entropy alloy blank;
placing the cooled high-entropy alloy blank into an extrusion container, wherein an extrusion rod is in clearance fit with the inner wall of the high-entropy alloy blank, the extrusion container is in clearance fit with the outer wall of the high-entropy alloy blank, and the top surface of the high-entropy alloy blank is parallel to the bottom surface of the extrusion rod;
driving an extrusion rod to move by a press, extruding the high-entropy alloy blank, and returning the extrusion rod to remove tailings after extruding the high-entropy alloy pipe;
and step five, carrying out vacuum recrystallization annealing treatment on the extruded high-entropy alloy pipe to obtain the high-entropy alloy pipe with the fine-grained structure.
12. The ultra-low temperature extrusion forming method for the high-entropy alloy thin-walled tube according to claim 11, characterized in that: in the fourth step, the extrusion forming temperature range of the high-entropy alloy blank is-196 ℃ to-160 ℃, and a single-pass or multi-pass extrusion mode is adopted.
13. The ultra-low temperature extrusion forming method for the high-entropy alloy thin-walled tube according to claim 11, characterized in that: and fifthly, carrying out vacuum recrystallization annealing on the extruded high-entropy alloy pipe at the temperature range of 600-1000 ℃ for 12-48h to obtain the high-entropy alloy pipe with the fine-grained structure.
14. The utility model provides a high entropy alloy thin wall pipe ultra-low temperature extrusion forming device which characterized in that: the high-entropy alloy billet extrusion die comprises an extrusion cylinder, an extrusion rod, a sleeve, a prestress ring, a lower die holder and an upper die holder, wherein the extrusion cylinder can contain a high-entropy alloy billet, the extrusion cylinder is arranged on the lower die holder, the extrusion rod is connected with the upper die holder, the extrusion rod and the extrusion cylinder are coaxially arranged, the upper die holder can drive the extrusion rod to reciprocate along the axis direction of the extrusion cylinder, the extrusion rod can extend into the extrusion cylinder, the lower die holder is provided with a through hole capable of allowing the extrusion rod to pass through, the side wall of the extrusion cylinder is provided with a cooling channel, the cooling channel can be communicated with an external cooling medium, and the extrusion cylinder is further connected with a temperature measuring element; the sleeve is sleeved outside the extrusion container, and the prestressed ring is sleeved outside the sleeve; one side of the lower die holder, which is close to the extrusion cylinder, is provided with a heat insulation plate, the extrusion cylinder, the sleeve and the prestress ring are all arranged on the heat insulation plate, and a heat insulation layer is sleeved outside the prestress ring.
15. The ultra-low temperature extrusion forming device for the high-entropy alloy thin-walled tube according to claim 14, characterized in that: the lower die holder is arranged on a press platform, the upper die frame is arranged on the press upper platform, the upper die frame is slidably connected with the press upper platform, a guide pillar is further arranged between the press platform and the press upper platform, and the upper die frame is slidably sleeved outside the guide pillar; the external cooling medium is liquid nitrogen, the external cooling medium is connected with a liquid nitrogen circulating flow control element, the extrusion cylinder is connected with a control unit, and the liquid nitrogen circulating flow control element and the temperature measuring element are respectively connected with the control unit.
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