A method for preparing fine-grained / ultra-fine-grained niobium alloy material
By controlling temperature, strain rate, and cooling during friction stir processing, niobium alloys achieve fine or ultrafine grain structures with enhanced mechanical properties, addressing the limitations of existing methods.
Patent Information
- Application Number
- CN202211724439.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Priority Date
- 2022-10-28
- Filing Date
- 2022-12-30
- Publication Date
- 2024-12-10
- Estimated Expiration
- 2042-12-30
AI Technical Summary
Existing methods fail to effectively prepare niobium alloys with fine or ultrafine grain structures due to high melting points, leading to materials with high strength but low plasticity, and there is a lack of specific preparation technology for high melting point materials using friction stir processing.
A method for preparing niobium alloys with controlled maximum temperature, strain rate, and cooling rate during friction stir processing, using inert gas protection and specific tool parameters to achieve fine or ultrafine grain structures.
The method results in niobium alloys with improved strength and plasticity, offering excellent mechanical properties and broad industrial application prospects.
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Figure CN116083822B_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of metal material processing, and in particular relates to a method for preparing a niobium alloy material with a fine grain / ultrafine grain structure. Background Art
[0002] Refractory metal materials are widely used in aviation, aerospace, nuclear power and other fields due to their high melting point. Niobium alloys are the preferred materials due to their low density, high ductility and good formability. In addition, it is worth noting that niobium alloys have high corrosion resistance, good biocompatibility and bone integration properties. People are very interested in using them as orthopedic implants, surgical tools and cardiovascular stents, but the disadvantage of relatively low strength seriously restricts the development and application of niobium alloys.
[0003] At present, severe plastic deformation (SPD) can be used to achieve grain refinement and thus improve the strength and plasticity of materials. However, due to the introduction of a large number of crystal defects in the process of preparing ultrafine-grained materials by the SPD method, most of the grain boundaries are in a non-equilibrium state, and the extremely fine grains limit the ability of dislocation activity, so that these materials cannot accumulate more defects in the subsequent tensile deformation process to maintain uniform plastic deformation. Therefore, ultrafine-grained materials prepared by SPD generally have the problem of high strength but low plasticity. In recent years, a new type of ultrafine-grained material preparation process—Friction stir processing (FSP)—has received more and more attention. Compared with ultrafine-grained materials prepared by SPD, FSP ultrafine-grained structures are uniform and stable, and have excellent mechanical properties.
[0004] However, researchers at home and abroad have only used FSP technology to prepare fine / ultrafine grains in metal materials with relatively low melting points, such as Al, Mg, Cu alloys and steel. FSP for high melting point materials, especially niobium alloys, is still a blank, and no specific preparation technology has been found. Therefore, it is necessary to control the key process of friction stir processing to meet the requirements of industrial preparation of fine / ultrafine grains of high melting point niobium alloy materials. Summary of the invention
[0005] The technical problem to be solved by the present invention is to provide a method for preparing a niobium alloy material with a fine grain / ultrafine grain structure in view of the deficiencies in the above-mentioned prior art. The method introduces a method for controlling the maximum temperature and strain rate in the processing zone to control the stir friction processing process, thereby realizing the preparation of the niobium alloy material with a fine grain / ultrafine grain structure, and the grain size of the niobium alloy can be controlled with the strain rate (determined by the tool size and rotation speed), heat input (determined by the tool size, rotation speed and travel speed) and cooling rate (determined by the inert gas flow rate).
[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing a fine-grained / ultra-fine-grained niobium alloy material, characterized in that it includes performing a stir friction processing on a niobium alloy plate, protecting and cooling the processing area with an inert gas during the processing, and controlling the maximum temperature of the processing area to 700°C to 1300°C, and the strain rate to 30s -1 ~200s -1 , so that the processing area obtains a niobium alloy material with a fine grain / ultrafine grain structure; the process parameters of the friction stir processing include: a tool speed of 500rpm to 2000rpm, a travel speed of 5mm / min to 400mm / min; and an inert gas flow rate of 1L / min to 10L / min.
[0007] The above-mentioned method for preparing a fine-grained / ultrafine-grained niobium alloy material is characterized in that the stirring head tool material used in the stir friction processing is an iridium-based alloy or a tungsten-based alloy, the stirring head diameter is 4mm to 10mm, and the stirring head shoulder diameter is 12mm to 18mm.
[0008] The above-mentioned method for preparing a fine-grained / ultra-fine-grained niobium alloy material is characterized in that the thickness of the niobium alloy plate is 1 mm to 10 mm.
[0009] The above-mentioned method for preparing a fine-grained / ultra-fine-grained niobium alloy material is characterized in that the mass purity of the inert gas is ≥99.99%;
[0010] The above-mentioned method for preparing a fine-grained / ultra-fine-grained niobium alloy material is characterized in that, in the friction stir processing, a single-pass processing method or a multi-pass overlapping processing method is adopted.
[0011] The above-mentioned method for preparing a fine-grained / ultra-fine-grained niobium alloy material is characterized in that the width of the processing area in the single-pass processing method is 4 mm to 10 mm.
[0012] The above-mentioned method for preparing a fine-grained / ultrafine-grained niobium alloy material is characterized in that the width of the processing area of each pass in the multi-pass overlapping processing method is 4mm to 10mm, and the width of the overlapping processing area between the previous and next passes is 1 / 4 to 1 / 3 of the width of the single-pass processing area.
[0013] Compared with the prior art, the present invention has the following advantages:
[0014] 1. The preparation method of the present invention introduces a method of controlling the maximum temperature and strain rate in the processing zone to control the stir friction processing process, thereby realizing the preparation of fine-grained / ultra-fine-grained niobium alloy materials. In addition, the grain size of the niobium alloy can be controlled with the strain rate (determined by the tool size and rotation speed), heat input (determined by the tool size, rotation speed and travel speed) and cooling rate (determined by the inert gas flow rate).
[0015] 2. The method of the present invention is simple to operate, has a stable process, and is highly controllable. The prepared fine-grained / ultrafine-grained niobium alloy material has excellent strength and plasticity, and high comprehensive mechanical properties. It will have broad industrial application prospects in the field of niobium alloy material preparation.
[0016] 3. The multi-pass overlapping processing method of the present invention can prepare a large-area niobium alloy with a fine-grained / ultra-fine-grained structure, and the mechanical properties of the large-area niobium alloy material prepared are not significantly reduced compared with the single-pass processing method.
[0017] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 This is the microstructure diagram of the fine-grained Nb-1Zr alloy prepared by friction stir processing in Example 1 of the present invention.
[0019] Figure 2 This is the microstructure diagram of the ultrafine-grained NbHf10-1 alloy prepared by friction stir processing in Example 2 of the present invention.
[0020] Figure 3 This is the microstructure diagram of fine-grained pure niobium prepared by friction stir processing in Example 3 of the present invention. DETAILED DESCRIPTION
[0021] Example 1
[0022] A 5mm thick Nb-1Zr alloy sheet was used, whose chemical composition by weight percentage was 0.98% Zr, 0.0008% Cr, 0.0025% Fe, 0.002% C, 0.007% O, and the balance was Nb; the yield strength was 125MPa, the tensile strength was 255MPa, and the elongation was 48%. An iridium-based alloy stirring head with a shoulder diameter of 15mm and a stirring head diameter of 6mm was used for friction stir processing. A single-pass processing method was used, and the width of the single-pass processing area was 6mm. The tool speed was 1600rpm and the travel speed was 200mm / min. The processing area was protected and cooled by inert gas, and the inert gas flow rate was 10L / min. During the processing, the temperature of the processing area was up to 850℃, and the strain rate was 135s -1 The processing area obtains fine-grained niobium alloy structure, and the average grain size of the niobium alloy is 2μm. Figure 1 The room temperature tensile test shows that the yield strength is as high as 203MPa, the tensile strength is 405MPa, and the uniform elongation is 55%, which greatly improves the mechanical properties compared with the unprocessed plate.
[0023] Comparative Example 1
[0024] A 5mm thick Nb-1Zr alloy plate was used, whose chemical composition by weight percentage was 0.98% Zr, 0.0008% Cr, 0.0025% Fe, 0.002% C, 0.007% O, and the balance was Nb; the yield strength was 125MPa, and the tensile strength was 255MPa. An iridium-based alloy stirring head with a shoulder diameter of 10mm and a stirring head diameter of 5mm was used for friction stir processing. A single-pass processing method was used, with a single-pass processing area width of 5mm, a tool speed of 450rpm, and a travel speed of 100mm / min. The processing area was protected and cooled by inert gas, and the inert gas flow rate was 5L / min. During the processing, the temperature of the processing area was as high as 650℃. Under this parameter, the niobium alloy was not fully softened, tunnel-type defects appeared in the processing area, and the mechanical properties were seriously reduced.
[0025] Example 2
[0026] A 3mm thick NbHf10-1 alloy plate was used, whose chemical composition by weight percentage was 0.55% Zr, 9.98% Hf, 0.90% Ti, 0.35% W, 0.40% Ta, and the balance was Nb; the yield strength was 300MPa, the tensile strength was 420MPa, and the elongation was 40%. A tungsten-based alloy stirring head with a shoulder diameter of 12mm and a stirring head diameter of 4mm was used for stir friction processing. A large-area plate was prepared by multi-pass overlapping stir friction processing. The width of the processing area of each pass was 4mm, and the width of the overlapping processing area between the front and rear passes was 1 / 3 of the width of the single-pass processing area. The tool speed was 1300rpm and the travel speed was 30mm / min. The processing area was protected and cooled by inert gas, and the inert gas flow rate was 8L / min. During the processing, the temperature of the processing area was up to 900℃, and the strain rate was 120s -1 The ultrafine grain niobium alloy structure is obtained in the processing area, and the average grain size of the niobium alloy is 0.7μm. Figure 2 The room temperature tensile test shows that the yield strength is as high as 400MPa, the tensile strength is 600MPa, and the uniform elongation is 50%, which greatly improves the mechanical properties compared with the unprocessed plate.
[0027] Comparative Example 2
[0028] A 3mm thick NbHf10-1 alloy plate was used, and its chemical composition by weight percentage was 0.55% Zr, 9.98% Hf, 0.90% Ti, 0.35% W, 0.40% Ta, and the balance was Nb; the yield strength was 300MPa, the tensile strength was 420MPa, and the elongation was 40%. An iridium-based alloy stirring head with a shoulder diameter of 25mm and a stirring head diameter of 12mm was used for friction stir processing. A single-pass processing method was used, and the width of the single-pass processing area was 12mm. The tool speed was 2000rpm, the travel speed was 80mm / min, and the processing area was not protected by inert gas. During the processing, the temperature of the processing area was as high as 1400℃, and severe oxidation occurred in the processing area, and the mechanical properties were seriously reduced.
[0029] Example 3
[0030] A 6mm thick 99.9% pure niobium plate with a yield strength of 110MPa, a tensile strength of 200MPa, and an elongation of 62% was used. A tungsten-based alloy stirring head with a shoulder diameter of 18mm and a stirring head diameter of 10mm was used for friction stir processing. A single-pass processing method was used, with a single-pass processing area width of 10mm, a tool speed of 700rpm, a travel speed of 50mm / min, and an inert gas was used to protect and cool the processing area. The inert gas flow rate was 3L / min. During the processing, the temperature of the processing area was up to 1100℃, and the strain rate was 100s -1 The processing area obtains fine-grained niobium alloy structure, and the average grain size of the niobium alloy is 9μm. Figure 3 The room temperature tensile test shows that the yield strength is as high as 150MPa, the tensile strength is 270MPa, and the uniform elongation is 70%, which greatly improves the mechanical properties compared with the unprocessed plate.
[0031] Example 4
[0032] A 1mm thick 99.9% pure niobium plate with a yield strength of 100MPa, a tensile strength of 190MPa, and an elongation of 60% was used. A tungsten-based alloy stirring head with a shoulder diameter of 12mm and a stirring head diameter of 4mm was used for friction stir processing. A single-pass processing method was used, with a single-pass processing area width of 4mm, a tool speed of 500rpm, and a travel speed of 5mm / min. The processing area was protected and cooled by inert gas, and the inert gas flow rate was 1L / min. During the processing, the temperature of the processing area was up to 700℃, and the strain rate was 30s -1 The processed area obtains ultrafine-grained niobium alloy structure, with an average grain size of 0.8μm. The room temperature tensile test shows that the yield strength is as high as 140MPa, the tensile strength is 230MPa, and the uniform elongation reaches 75%, which greatly improves the mechanical properties compared with the unprocessed plate.
[0033] Example 5
[0034] A 10mm thick Nb-1Zr alloy plate was used, and its chemical composition by weight percentage was 0.96% Zr, 0.0007% Cr, 0.0029% Fe, 0.003% C, 0.008% O, and the balance was Nb; the yield strength was 120MPa, the tensile strength was 210MPa, and the elongation was 57%. A tungsten-based alloy stirring head with a shoulder diameter of 18mm and a stirring head diameter of 10mm was used for stir friction processing. A large-area plate was prepared by multi-pass overlapping stir friction processing. The width of the processing area of each pass was 10mm, and the width of the overlapping processing area between the front and rear passes was 1 / 4 of the width of the single-pass processing area. The tool speed was 2000rpm and the travel speed was 400mm / min. The processing area was protected and cooled by inert gas, and the inert gas flow rate was 10L / min. During the processing, the temperature of the processing area was up to 1300℃, and the strain rate was 200s -1 The processed area obtains fine-grained niobium alloy structure with an average grain size of 15μm. The room temperature tensile test shows that the yield strength is as high as 145MPa, the tensile strength is 240MPa, and the uniform elongation reaches 67%. The mechanical properties are greatly improved compared with the unprocessed plate.
[0035] Example 6
[0036] 8mm thick NbHf10-1 alloy plate was used, and its chemical composition by weight percentage was 0.58% Zr, 10.01% Hf, 0.90% Ti, 0.37% W, 0.35% Ta, and the balance was Nb; the yield strength was 310MPa, the tensile strength was 430MPa, and the elongation was 43%. The friction stir processing was performed using an iridium-based alloy stirring head with a shoulder diameter of 15mm and a stirring head diameter of 8mm. The single-pass processing method was adopted, and the width of the single-pass processing area was 8mm. The tool speed was 1000rpm and the travel speed was 50mm / min. The processing area was protected and cooled by inert gas, and the inert gas flow rate was 5L / min. During the processing, the temperature of the processing area was up to 1000℃, and the strain rate was 100s -1 The processed area obtains fine-grained niobium alloy structure with an average grain size of 5μm. The room temperature tensile test shows that the yield strength is as high as 330MPa, the tensile strength is 480MPa, and the uniform elongation reaches 55%. The mechanical properties are greatly improved compared with the unprocessed plate.
[0037] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent changes made to the above embodiments based on the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.
Claims
1. A method for preparing a fine-grained / ultra-fine-grained niobium alloy material, characterized in that: The process includes friction stir processing of niobium alloy plates, in which the processing area is protected and cooled by inert gas, and the maximum temperature of the processing area is controlled to be 700℃~1300℃, and the strain rate is 30s -1 ~200s -1 , so that the processing area can obtain the niobium alloy material with fine grain / ultrafine grain structure; The process parameters of the friction stir processing include: tool rotation speed of 500rpm~2000rpm, travel speed of 5mm / min~400mm / min; inert gas flow rate of 1L / min~10L / min; the stirring head tool material used in the friction stir processing is iridium-based alloy or tungsten-based alloy, the stirring head diameter is 4mm~10mm, and the stirring head shoulder diameter is 12mm~18mm.
2. The method for preparing a fine-grained / ultra-fine-grained niobium alloy material according to claim 1, characterized in that: The thickness of the niobium alloy plate is 1 mm to 10 mm.
3. The method for preparing a fine-grained / ultra-fine-grained niobium alloy material according to claim 1, characterized in that: The mass purity of the inert gas is ≥99.99%.
4. The method for preparing a fine-grained / ultra-fine-grained niobium alloy material according to claim 1, characterized in that: In the friction stir processing, a single-pass processing method or a multi-pass overlapping processing method is adopted.
5. The method for preparing a fine-grained / ultra-fine-grained niobium alloy material according to claim 4, characterized in that: In the single-pass processing method, the width of the processing area is 4 mm to 10 mm.
6. The method for preparing a fine-grained / ultra-fine-grained niobium alloy material according to claim 4, characterized in that: In the multi-pass overlapping processing method, the width of the processing area of each pass is 4mm-10mm, and the width of the overlapping processing area between the front and rear passes is 1 / 4-1 / 3 of the width of the single-pass processing area.