CN-117721332-B - Method for smelting continuous casting refractory high-entropy alloy hollow bar blank by using electron beam cooling bed

CN117721332BCN 117721332 BCN117721332 BCN 117721332BCN-117721332-B

Abstract

The invention relates to a method for smelting a continuous casting refractory high-entropy alloy hollow bar blank by using an electron beam cooling bed, which is characterized in that two electron guns are adopted for heating, wherein the first electron gun is used for remelting alloy materials in the cooling bed and then injecting the remelted alloy materials into an annular crystallizer, the second electron gun is used for keeping the alloy liquid at the top of the annular crystallizer heated, so that the alloy liquid maintains enough heat and has good fluidity, the alloy liquid flows into the bottom from the top of the annular crystallizer, the annular crystallizer has a water cooling effect, the temperature of the annular crystallizer is gradually reduced, the alloy liquid is solidified on a pull ingot head, and meanwhile, the continuous solidification of metal liquid is realized by pulling a bottom support of a pull ingot mechanism arranged below the crystallizer at a certain speed, so that the hollow bar blank is obtained. The invention solves the technical problem of the high-melting point alloy hollow rod blank prepared by the existing electron beam cold bed smelting method, and avoids the working procedures of machining, drilling and the like in the production of seamless pipes, thereby realizing the manufacture of short-flow pipe blanks and improving the production efficiency and the material utilization rate.

Inventors

XUE YUNFEI
CAO TANGQING
Ma Xukui
WANG BENPENG

Assignees

北京理工大学唐山研究院

Dates

Publication Date: 20260512
Application Date: 20230829

Claims (4)

1. A method for smelting a continuous casting refractory high-entropy alloy hollow bar blank by using an electron beam cooling bed, which is characterized by comprising the following steps: S1, weighing refractory high-entropy alloy materials with corresponding mass according to the size requirement of a target hollow rod blank, and cleaning; S2, according to the sizes of the materials and a cooling bed, placing one part of the alloy materials into a feed bin, paving the other part of the alloy materials into the cooling bed in an electron beam smelting furnace, selecting an annular crystallizer according to the size of a target hollow rod blank, installing the annular crystallizer below a pouring opening of the cooling bed, wherein the annular crystallizer comprises a cylindrical water-cooling outer ring and a cylindrical water-cooling inner core, arranging an ingot pulling mechanism below the annular crystallizer, arranging an ingot pulling head on a bottom support of the ingot pulling mechanism, processing the ingot pulling head by the alloy of the target hollow rod material, selecting the size of the ingot pulling head according to the size of the target hollow rod blank, corresponding to an annular structure between the outer ring and the inner core of the annular crystallizer, clamping and connecting the ingot pulling head with the bottom support of the ingot pulling mechanism, upwards moving the bottom support of the ingot pulling mechanism to enable the ingot pulling head to enter the annular crystallizer, and closing a furnace door; S3, carrying out vacuum pre-pumping on the electron beam melting furnace to below 10Pa, and carrying out high vacuum pumping on the electron beam melting furnace to below 5 multiplied by 10 -1 Pa; S4, starting a first electron gun positioned above the cooling bed to heat alloy materials positioned in the cooling bed, starting a second electron gun positioned above the crystallizer to heat the ingot pulling head, and gradually increasing input power until the materials in the cooling bed and the surface of the ingot pulling head are completely melted; S5, selecting stable heating power of a first electron gun according to the melting point and the size of the materials, selecting stable heating power of a second electron gun according to the melting point of the smelting materials and the diameter of the crystallizer, starting a feeding motor to push alloy materials in a feeding bin to a cooling bed after the first electron gun and the second electron gun work stably, and keeping feeding at a feeding speed of 5-10mm/min to enable the alloy materials to be melted and flow into the annular crystallizer; S6, setting ingot pulling speed of 2-5mm/min by the ingot pulling mechanism according to the speed of molten alloy flowing into the crystallizer, so that the solidification of molten metal in the whole system and the ingot pulling mechanism in the crystallizer and the downward pulling of a bar blank can be continuously carried out; S7, the ingot pulling mechanism pulls the collet to a specified position, then stops electron beam scanning, separates the upper part of the furnace body from the lower part of the furnace body after the furnace is cooled to 50 ℃, pushes the lower furnace body, the hollow cast ingot and the inner core of the crystallizer out of the furnace body through the hydraulic conveying device, then removes the inner core positioned at the upper part of the cast ingot, separates the ingot pulling head from the collet of the ingot pulling mechanism, and takes out the refractory high-entropy alloy hollow bar blank.
2. The method for continuously casting refractory high-entropy alloy hollow bar blank by electron beam cold hearth according to claim 1, wherein the first electron gun adopts a scanning strategy of electron beam width of 1.5-5 mm, scanning frequency of 200Hz, scanning area rectangle with length at least 100mm larger than the width of the feed bin and width equivalent to the width of the cold hearth, and scanning area at the center of the cold hearth.
3. The method for continuously casting refractory high-entropy alloy hollow bar blank by using an electron beam cooling bed according to claim 1, wherein the scanning strategy of the second electron gun is that the electron beam width is 1.5-5 mm, the scanning frequency is 200Hz, the scanning area is annular, the outer diameter of the scanning area is 5-15 mm smaller than the outer diameter of the crystallizer, and the inner diameter of the scanning area is 5-15 mm larger than the inner diameter of the crystallizer.
4. A method of continuous casting a refractory high entropy alloy hollow bar according to claim 1, wherein the ingot withdrawal speed and feed rate are such that the level of metal in the toroidal crystallizer is maintained between 30mm and 40 mm.

Description

Method for smelting continuous casting refractory high-entropy alloy hollow bar blank by using electron beam cooling bed Technical Field The invention relates to a smelting and forming method of refractory high-entropy alloy, in particular to a method for smelting and continuously casting a refractory high-entropy alloy hollow rod blank by using an electron beam cooling bed. Background Refractory high-entropy alloys generally refer to a new class of alloys with titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, and tungsten as the main constituent elements. The alloy has the comprehensive performance advantages of high strength, high hardness, high wear resistance, high temperature resistance, irradiation resistance and the like, so that the alloy has wide application potential in the fields of aerospace structural members, weapon and missile warheads, nuclear reactor structural materials, wear-resistant materials, biomedical materials, ship and ocean engineering materials, thermoelectric materials and the like. However, the alloy has the advantages of multiple kinds of constituent elements, high melting point, large difference, high activity and sensitivity to impurity elements, and the production and preparation of the alloy are challenged. The refractory high-entropy alloy is prepared through mechanical alloying, laser cladding, arc smelting, cold crucible induction smelting, electron beam cold bed smelting, etc. Among them, arc melting, cold crucible induction melting and electron beam melting are the most common methods currently used for preparing refractory high-entropy alloys. But for the refractory high-entropy alloy with the melting point exceeding 2000 ℃, the size of the alloy which can be prepared is smaller, and the continuous molding of large-sized cast ingots is difficult to realize, while the vacuum electron beam melting method has the advantages of high heating temperature, high superheat degree, good fluidity of molten metal, capability of realizing the continuous molding of large-sized cast ingots and high production efficiency. In addition, in practical engineering, the alloy is required to be prepared into pipes in many application occasions of difficult-to-hold high-entropy alloy, such as a warhead shell, a nuclear reactor cold water pipeline, a rocket engine nozzle and the like. At present, a refractory alloy seamless pipe is generally obtained by forging and rolling after a solid ingot blank is machined and drilled, the working procedure is complex, and the material utilization rate is low. Therefore, the hollow refractory high-entropy alloy cast ingot is cast, and working procedures such as machining, drilling and the like can be omitted in the production of the pipe, so that the short-flow pipe blank manufacturing is realized. The refractory high-entropy alloy prepared by the existing electron beam cold bed smelting method is a plate or bar, and an annular crystallizer is needed in the aspect of hollow rod blank preparation, but the ingot pulling failure is caused by core holding easily due to shrinkage in the solidification and cooling of the hollow rod blank, so that the preparation of the refractory alloy hollow rod blank is still blank at present. Disclosure of Invention In order to solve the technical problems, the invention reasonably controls the liquid level of the molten metal in the crystallizer through matching the ingot pulling speed and the feeding speed, so that the solidified hollow bar blank leaves the ingot core before larger shrinkage occurs, and the occurrence of core holding is avoided. Based on the above, the invention provides a process method which is suitable for electron beam cold bed smelting to produce a refractory high-entropy alloy hollow rod blank taking titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum and tungsten as main constituent elements. The method for smelting the continuous casting refractory high-entropy alloy hollow bar blank by using the electron beam cooling bed is characterized by comprising the following steps of: (1) Weighing refractory high-entropy alloy materials with corresponding mass according to the size requirement of a target hollow rod blank, and cleaning; (2) According to the sizes of the materials and the cooling bed, placing one part of the alloy materials into a feed bin, paving the other part of the alloy materials into the cooling bed in an electron beam smelting furnace, selecting an annular crystallizer according to the size of a target hollow rod blank, installing the annular crystallizer below a pouring opening of the cooling bed, wherein the annular crystallizer comprises a cylindrical water-cooling outer ring and a cylindrical water-cooling inner core, arranging a pulling ingot mechanism below the annular crystallizer, arranging a pulling ingot head on a pulling ingot mechanism base, processing the pulling ingot head by the alloy of the target hollow rod m