Vacuum cold crucible suspension smelting method for titanium and titanium alloy cast ingots
By using a suspended crucible feeding process and a stepped temperature control process, the problems of uneven composition and unstable mechanical properties of titanium and titanium alloy ingots in vacuum cold crucible suspension melting were solved, and ingot production with high uniformity and consistency was achieved.
Patent Information
- Application Number
- CN202511129515.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-13
- Publication Date
- 2025-11-07
AI Technical Summary
In existing vacuum cold crucible suspension melting methods, titanium and titanium alloy ingots lose a large amount of heat when they come into contact with the crucible at the bottom, forming a thick solidified shell, which leads to compositional inhomogeneity and deviations in mechanical properties.
By employing a suspended charging design and a stepped temperature control process, the contact between the molten metal and the bottom of the crucible is controlled through stages of suspended crucible feeding, preheating and homogenization, softening and homogenization, melting and melting heat preservation. Combined with high-energy homogenization heat preservation, the formation of solidified shells is reduced and the uniformity of composition is improved.
It significantly reduces the quality of the solidified shell, improves the uniformity of composition, reduces the difference in chemical composition between the top and bottom of the ingot to less than 0.05%, improves the consistency of mechanical properties, reduces the tensile strength deviation to ≤3MPa, and narrows the elongation fluctuation range by 50%.
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Figure CN120905549A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of titanium and titanium alloy smelting, and particularly relates to a titanium and titanium alloy ingot vacuum cold-crucible suspension smelting method. BACKGROUND
[0002] The cold-crucible suspension smelting technology is a new technology that a water-cooled metal crucible with a slit is placed in an alternating magnetic field of a coil to inductively smelt the furnace charge. The technology is particularly suitable for smelting or remelting of active metals, refractory alloys, high-purity materials and high-concentration contaminated materials. The technology has the advantages of low equipment investment and operation cost, and good effects on the quality and uniformity of titanium and titanium alloy ingots. Therefore, the method is the preferred process method for producing titanium and titanium alloy ingots for important uses such as aviation, aerospace, ships, chemical industry, petroleum, automobiles, medical treatment and nuclear power, and has a very broad development and utilization prospect.
[0003] The vacuum cold-crucible suspension smelting technology has many advantages, but there is a problem that the bottom of the crucible has a whole structure, and a large amount of heat of the titanium and titanium alloy casting melt is lost at the bottom in contact with the crucible. A relatively thick solid shell is formed, which often exceeds 1 / 3 of the total volume, and the weight of the solid shell exceeds 20% of the total weight. When the weight of the solid shell exceeds a certain weight, the uniformity of the main elements of the titanium and titanium alloy ingot is poor. Therefore, further research is needed.
[0004] Therefore, there is a need for improvement of the vacuum cold-crucible suspension smelting method for titanium and titanium alloy ingots in the prior art. SUMMARY
[0005] In view of the above, the purpose of the embodiments of the present application is to provide a vacuum cold-crucible suspension smelting method for titanium and titanium alloy ingots. The weight of the solid shell formed by the molten titanium metal liquid in contact with the crucible at the bottom is reduced, the range of the main element content of the titanium alloy ingot is reduced, the uniformity is optimized, and the mechanical property deviation of the sample is reduced.
[0006] Based on the above purpose, the embodiments of the present application provide a vacuum cold-crucible suspension smelting method for titanium and titanium alloy ingots, which comprises the following steps: S1, a crucible charging stage: the furnace charge is suspended in the cold crucible, the lower edge of the furnace charge is kept at a suspended distance from the bottom of the crucible, and the cold crucible is suspended in the smelting furnace; S2, a preheating and homogenizing stage: the smelting furnace is evacuated to a preset vacuum degree, the smelting power is turned on, the furnace charge is preheated, the temperature of the core and the surface layer of the furnace charge reaches a first preset temperature range, and the temperature is maintained; S3, a softening and uniform temperature stage: the power is increased to heat the furnace charge to a semi-molten state, and the core of the furnace charge is maintained at a second preset temperature; S4, a melting stage: the power and frequency are further increased to completely melt the furnace charge; S5, melting holding stage: further increase the power and frequency to the maximum power and maximum frequency of the smelting furnace device, and the completely molten metal liquid is held to realize temperature equalization; S6, casting stage: the molten metal after temperature equalization is poured into an ingot mold to obtain an ingot.
[0007] In some embodiments, in S1, the overhanging distance is 50-100 mm, and the upper part of the charge is a steamed bun-shaped protrusion.
[0008] In some embodiments, in S1, the charge includes elemental alloy, intermediate alloy, or recycled titanium alloy ingot with a composition difference greater than 0.4%.
[0009] In some embodiments, in S2, after vacuumizing to 0.05 Pa, the smelting power is turned on, the preheating power is 400-450 kW, the frequency is 5.0-6 kHz, and the preheating time is 6-12 minutes. In some embodiments, in S2, the first preset temperature range is 1350-1450℃, and the holding time is at least 5 minutes.
[0010] In some embodiments, in S3, the power is increased to 500-550 kW for constant temperature heating for 6-12 minutes, and the temperature of the charge in the semi-molten state is 1550-1610℃.
[0011] In some embodiments, in S3, the holding time is at least 5 minutes, and the second preset temperature reached by the core of the charge is 1600℃.
[0012] In some embodiments, in S4, the power is increased to 850-900 kW, and the frequency is gradually increased to 7.5-8 kHz until the charge is completely molten.
[0013] In some embodiments, in S5, the holding time is 6-20 minutes under the maximum power and maximum frequency to reduce the temperature difference of the molten metal up and down and inside and outside.
[0014] In some embodiments, in S6, the ingot mold is a preheated mold coated with refractory coating, and the pouring is completed in a vacuum environment.
[0015] The present application has at least the following technical effects: 1. Significantly reduce the formation of skull: by the overhanging charging design of the said crucible charging stage, combined with the semi-molten suspension control of the softening temperature equalization stage, the skull quality is reduced to below 8%, which fundamentally reduces the contact solidification of the molten metal with the bottom of the crucible and improves the utilization rate of raw materials; 2. Achieve ultra-high uniformity of composition: relying on the stepwise temperature control process, combined with high-energy homogenization holding, the chemical composition content difference between the top and bottom of the ingot is stably below 0.05%; 3. Mechanical property consistency breakthrough: the essential improvement of component uniformity directly leads to the improvement of mechanical property, the tensile strength deviation of the top and bottom of the ingot is less than or equal to 3MPa, the fluctuation range of elongation is narrowed by more than 50%, and the mechanical property dispersion problem caused by component segregation of the traditional ingot is solved. BRIEF DESCRIPTION OF DRAWINGS
[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other embodiments can also be obtained from these drawings without creative labor.
[0017] Figure 1 A schematic diagram of an embodiment of a titanium and titanium alloy ingot vacuum cold crucible suspension smelting method provided by the present application is shown in the figure. Figure 2 A smelting stage curve provided by the present application is shown in the figure. DETAILED DESCRIPTION
[0018] In order to make the purpose, technical solutions and advantages of the present application more clear and obvious, the following will further describe the embodiments of the present application in combination with specific embodiments and with reference to the drawings.
[0019] The terms "include" and "have" and any variations thereof in the specification and claims of the present application and the above-mentioned drawing description are intended to cover non-exclusive inclusion; the terms "first", "second" and the like in the specification and claims of the present application or the above-mentioned drawings are used to distinguish different objects, not to describe a specific order. The meaning of "a plurality of" is two or more, unless otherwise explicitly and specifically limited.
[0020] In addition, the reference to "embodiments" in this document means that the specific features, structures or characteristics described in combination with the embodiments can be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily mean the same embodiment, nor is it an independent or alternative embodiment to other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.
[0021] As Figure 1 A schematic diagram and stage curve of an embodiment of a titanium and titanium alloy ingot vacuum cold crucible suspension smelting method provided by the present application are shown in the figure, specifically, the method comprises: S1, crucible charging stage: suspending the furnace charge in the cold crucible, the lower edge of the furnace charge is kept a suspended distance from the bottom of the crucible, and the cold crucible is suspended in the smelting furnace; S2, preheating homogenization stage: after the smelting furnace is vacuumed to a preset vacuum degree, the smelting power is turned on to preheat the furnace charge, so that the core and surface layers of the furnace charge reach a first preset temperature range and are kept warm; S3, softening homogenization stage: the power is increased to heat the furnace charge to a semi-molten state, and the core of the furnace charge is kept warm to a second preset temperature; S4, melting stage: the power and frequency are further increased to completely melt the furnace charge; S5, melting and keeping warm stage: the power and frequency are further increased to the maximum power and maximum frequency of the smelting furnace equipment, and the completely melted metal liquid is kept warm to achieve homogenization; S6, casting stage: the homogenized molten metal is poured into an ingot mold to obtain an ingot.
[0022] Further, in S1, the crucible charging stage, the cold crucible bottom furnace charge is suspended to avoid contact between the furnace charge and the crucible bottom. The suspension distance is 50-100 mm, and the upper part of the furnace charge is a steamed bun-shaped protrusion. The furnace charge includes elemental alloy, intermediate alloy, or recycled titanium alloy ingot with a composition difference greater than 0.4%.
[0023] Further, in S2, the preheating power is increased, and the preheating time is extended to make the core and surface layer temperatures of the furnace charge as consistent as possible. Specifically, after vacuuming to 0.05 Pa, the smelting power is turned on, the preheating power is 400-450 kW, the frequency is 5.0-6 kHz, and the preheating time is 6-12 minutes. The first preset temperature range is 1350-1450°C, and the keeping warm time is at least 5 minutes.
[0024] Further, in S3, the power is increased to 500-550 kW for constant temperature heating for 6-12 minutes, and the furnace charge temperature in the semi-molten state is 1550-1610°C. The keeping warm time is at least 5 minutes, and the second preset temperature reached by the core of the furnace charge is 1600°C. In this step, all the furnace charge is kept warm to a semi-molten state, the molten liquid is close to semi-suspension of the furnace charge, and contact between the molten liquid and the crucible bottom is avoided as much as possible.
[0025] Further, in S4, the power is increased to 850-900 kW, and the frequency is gradually increased to 7.5-8 kHz until the furnace charge is completely melted.
[0026] Further, in S5, the keeping warm time is 6-20 minutes under the maximum power and maximum frequency. After the furnace charge is completely melted, the power and frequency are continuously increased, and the keeping warm time is extended, so as to reduce the temperature difference between the upper and lower parts and the inner and outer parts of the molten metal as much as possible, without causing the induction coil to arc due to metal vapor.
[0027] Further, in S6, the ingot mold is a preheated and refractory-coated mold, and the pouring is completed in a vacuum environment.
[0028] The application will be further explained in connection with specific examples.
[0029] S1 Cracible charging stage: the elemental alloy (small particle size sponge titanium, metal aluminum particles), intermediate alloy (V-Al alloy, Zr-Al alloy) and other metal materials are added according to requirements, wherein the elemental alloy composition information is shown in Table 1; or the titanium and titanium alloy ingot materials with a composition content range greater than 0.4% are smelted by a vacuum self-consumption condensate shell furnace. The total weight of the materials is 35 Kg-58 Kg, and the charge is added into a 100 Kg cold crucible suspension smelting furnace. The charge requirement is that the lower edge of the charge is suspended 50-100 mm from the bottom of the cold crucible, and the upper part of the charge is in a steamed bun shape.
[0030] S2 Preheating and homogenizing stage: close the furnace door and cover, open the smelting chamber vacuum valve, and then open the slide valve pump, Roots pump ZJP1200 and Roots pump ZJP2500 in sequence. The smelting power is turned on when the vacuum reaches 0.05 Pa. The charge is preheated for 6-12 minutes by using a power of 400-450 kW and a frequency of 5.0 kHz. The completion sign is that the temperature of the charge reaches 1350-1450℃. It is maintained for more than 5 minutes to ensure that the core of the charge also reaches 1350-1450℃.
[0031] S3 Softening and temperature equalizing stage: the charge is preheated for 6-12 minutes by using a power of 500-550 kW and a frequency of 5.0 kHz. The completion sign is that the temperature of the charge reaches 1550-1610℃.
[0032] It is maintained for more than 5 minutes to ensure that the core of the charge reaches 1600℃.
[0033] S4 Melting stage: based on the softening and temperature equalizing stage of the charge, the power is increased by 350 kW, i.e. the power reaches 850-900 kW, and the frequency is gradually increased to 7.5 kHz. The completion sign is that the charge in the cold crucible is completely melted.
[0034] S5 Melting and holding stage: after the charge is completely melted, the power is continuously increased to the maximum power of the equipment 980 kW and the maximum frequency of the equipment 8.5 kHz, and the holding time is 6-20 minutes to reduce the temperature difference of the molten metal as much as possible.
[0035] S6 Casting stage: the molten metal is poured into an ingot mold.
[0036] Table 1 Elemental alloy composition information
[0037] The intermediate alloy is V-Al alloy and Zr-Al alloy.
[0038] Example 1 Table 2 Ti60 example batching table (50 kg)
[0039] As Figure 2 shown is a phase state diagram, in particular: S1 Cracible charging stage: according to the batching table 2, the elemental alloy Al, Mo, Zr, Ti and other metal materials are added, the total weight of the materials is 50 Kg, and the charge is added into a 100 Kg cold crucible suspension smelting furnace. The charge requirement: the lower edge of the charge is suspended 50-100 mm from the bottom of the cold crucible, and the upper part of the charge is in a steamed bun shape.
[0040] S2 Preheating homogenization stage: close the furnace door and cover, open the smelting chamber vacuum valve, and then open the slide valve pump, Roots pump ZJP1200 and Roots pump ZJP2500 in turn. When the vacuum reaches 0.05 Pa, the smelting power is turned on. The charge preheating stage. The power is 450 kW and the frequency is 5.0 kHz, and the charge is preheated for 6-12 minutes. The completion sign is that the temperature of the charge reaches 1400-1450℃. Keep for more than 5 minutes to ensure that the core of the charge also reaches 1400℃.
[0041] S3 Softening and temperature equalization stage: preheat the charge for 11 minutes using a power of 550 kW and a frequency of 5.0 kHz, and the completion sign is that the temperature of the charge reaches 1610℃. Keep for more than 7 minutes to ensure that the core of the charge reaches 1600℃.
[0042] S4 Melting stage: based on the softening and temperature equalization stage of the charge, the power is increased by 350 kW, i.e. the power reaches 900 kW, and the frequency is gradually increased to 7.5 kHz. The completion sign is that the charge in the cold crucible is completely melted.
[0043] S5 Melting and holding stage: after the charge is completely melted, the power is continuously increased to the maximum power of the equipment 980 kW and the maximum frequency of the equipment 8.5 kHz, and the holding time is 8 minutes, so as to reduce the temperature difference of the molten metal as much as possible.
[0044] S6 Casting stage: the molten metal is poured into the ingot mold.
[0045] The Ti60 ingot is sampled for composition analysis and mechanical property detection, and the results are as follows: Table 3 Composition analysis and mechanical property detection results of Ti60 Example 1
[0046] Example 2 Melting TC11 ingot raw material condition: the ingot weight is 43.57 Kg, which is smelted by a vacuum self-consumption shell furnace, and the sampling analysis shows that the Al content extreme difference is >0.4%, the Zr, Mo, Ni content extreme difference is >0.25%, and the tensile strength and yield strength deviation of different parts is greater than 15 MPa.
[0047] S1 crucible charging stage: the TC11 ingot is added into a 100 Kg cold crucible suspension smelting furnace. The requirements for charging are that the lower edge of the ingot is suspended 80-100 mm from the bottom of the cold crucible.
[0048] S2 preheating and homogenizing stage: the furnace door and cover are closed, the smelting chamber vacuum valve is opened, the slide valve pump, the Roots pump ZJP1200 and the Roots pump ZJP2500 are sequentially opened, and the smelting power is turned on when the vacuum reaches 0.05 Pa. The furnace charge is preheated. The power is 420 kW, the frequency is 5.0 kHz, and the furnace charge is preheated for 9 minutes. The completion sign is that the temperature of the furnace charge reaches 1400-1450℃. More than 5 minutes are maintained to ensure that the core of the furnace charge also reaches 1400℃.
[0049] S3 softening and homogenizing stage: the furnace charge is preheated for 8 minutes by using a power of 500 kW and a frequency of 5.0 kHz. The completion sign is that the temperature of the furnace charge reaches 1610℃. More than 7 minutes are maintained to ensure that the core of the furnace charge reaches 1600℃.
[0050] S4 melting stage: on the basis of the softening and homogenizing stage of the furnace charge, the power is increased by 350 kW, i.e., the power reaches 850 kW, and the frequency is gradually increased to 7.5 kHz. The completion sign is that the furnace charge in the cold crucible is completely melted.
[0051] S5 melting and holding stage: after the furnace charge is completely melted, the power is continuously increased to the maximum power 980 kW and the maximum frequency 8.5 kHz of the equipment, and holding is performed for 8 minutes to reduce the temperature difference of the molten metal as much as possible.
[0052] S6 casting stage: the molten metal is poured into an ingot mold.
[0053] The TC11 ingot is sampled for composition analysis and mechanical property detection, and the results are as follows: Table 4 Composition analysis and mechanical property detection of Example 2
[0054] As can be seen from the examples, the chemical composition content difference between the top end and the bottom end of the titanium alloy ingot poured by the smelting method provided by the application is less than 0.05%, and the uniformity is significantly improved. The mechanical property deviation between the top end and the bottom end of the titanium alloy ingot poured by the smelting method provided by the application is less than 3 MPa, which meets the application requirements. The skull quality of the titanium alloy ingot poured by the smelting method provided by the application is 8% or less, which is significantly reduced compared with 20%.
[0055] The above are exemplary embodiments disclosed by the present application, but it should be noted that various changes and modifications can be made without departing from the scope of the embodiments disclosed by the present application defined by the claims. The functions, steps and / or actions of the method claims described herein need not be performed in any particular order. Furthermore, although elements of the embodiments disclosed by the present application can be described or claimed in individual form, unless explicitly restricted, they can also be implemented in multiple forms.
[0056] It should be understood that, as used herein, the singular forms "a", "an" and "the" are intended to include plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising", or "includes" and / or "including" when used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.
[0057] The above-mentioned embodiment number of the embodiments of the present application is only for description, not representing the advantages or disadvantages of the embodiments.
[0058] Those skilled in the art should understand that the above discussion of any embodiment is only exemplary, and is not intended to imply that the scope of the embodiments disclosed by the present application (including the claims) is limited to these examples; the technical features in the above embodiments or different embodiments can also be combined, and there are many other changes of the different aspects of the embodiments of the present application as described above. In order to be brief, they are not provided in details. Therefore, any omission, modification, equivalent replacement, improvement, etc. made in the spirit and principles of the embodiments of the present application shall be included in the protection scope of the embodiments of the present application.
Claims
1. A vacuum cold crucible levitation melting method of titanium and titanium alloy ingot, characterized by, The method comprises the following steps: S1, a crucible charging stage: suspending the furnace charge in a cold crucible, the lower edge of the furnace charge being suspended at a distance from the bottom of the crucible, and the cold crucible being suspended in a smelting furnace; S2, a preheating and homogenizing stage: after the smelting furnace is vacuumized to a preset vacuum degree, the smelting power is turned on, the furnace charge is preheated, and the temperature of the core and the surface layer of the furnace charge reaches a first preset temperature range and is kept constant; S3, a softening and homogenizing stage: the power is increased to heat the furnace charge to a semi-molten state, and the core of the furnace charge is kept constant at a second preset temperature; S4, a melting stage: the power and frequency are further increased to completely melt the furnace charge; S5, a melting and keeping constant stage: the power and frequency are further increased to the maximum power and the maximum frequency of the smelting furnace equipment, and the completely molten metal liquid is kept constant to achieve temperature homogenization; S6, a casting stage: the molten metal after being kept constant is poured into an ingot mold to obtain an ingot.
2. The titanium and titanium alloy ingot vacuum cold crucible levitation melting process of claim 1, wherein, In S1, the suspension distance is 50-100 mm, and the upper part of the furnace charge is a steamed bun-shaped protrusion.
3. The titanium and titanium alloy ingot vacuum cold crucible levitation melting process of claim 1, wherein, In S1, the furnace charge comprises elemental alloy, intermediate alloy or recycled titanium alloy ingot with a composition difference greater than 0.4%.
4. The titanium and titanium alloy ingot vacuum cold crucible levitation melting process of claim 1, wherein, In S2, the vacuum is extracted to 0.05 Pa, and then the smelting power is turned on, the preheating power is 400-450 kW, the frequency is 5.0-6 kHz, and the preheating time is 6-12 minutes.
5. The titanium and titanium alloy ingot vacuum cold crucible levitation melting process of claim 1, wherein, In S2, the first preset temperature range is 1350-1450℃, and the keeping constant time is at least 5 minutes.
6. The titanium and titanium alloy ingot vacuum cold crucible levitation melting process of claim 1, wherein, In S3, the power is increased to 500-550 kW for constant heating for 6-12 minutes, and the temperature of the furnace charge in the semi-molten state is 1550-1610℃.
7. The titanium and titanium alloy ingot vacuum cold crucible levitation melting process of claim 1 wherein, In S3, the keeping constant time is at least 5 minutes, and the second preset temperature reached by the core of the furnace charge is 1600℃.
8. The titanium and titanium alloy ingot vacuum cold crucible levitation melting process of claim 1 wherein, In S4, the power is increased to 850-900 kW, and the frequency is gradually increased to 7.5-8 kHz until the furnace charge is completely melted.
9. The titanium and titanium alloy ingot vacuum cold crucible levitation melting process of claim 1 wherein, In S5, the temperature difference of the molten metal is reduced by keeping constant at the maximum power and the maximum frequency for 6-20 minutes.
10. The titanium and titanium alloy ingot vacuum cold crucible levitation melting process of claim 1 wherein, In S6, the ingot mold is a preheated mold coated with refractory coating, and the pouring is completed in a vacuum environment.