Preparation method of cobalt-based alloy casting

Abstract

The invention provides a preparation method of a cobalt-based alloy casting, which comprises the following steps: S1, raw material preparation: selecting the following raw materials in percentage by mass: 50-65% of cobalt, 20-30% of chromium, 5-15% of tungsten, 3-8% of nickel, 0.2-0.8% of carbon and the balance of inevitable impurities, pretreating the raw materials to remove impurities such as surface oil stains and oxides; s2, smelting: adding the pretreated raw materials into a vacuum induction smelting furnace; according to the preparation method of the cobalt-based alloy casting, the raw material ratio and pretreatment are accurately controlled, smelting is conducted under the vacuum condition, and electromagnetic stirring is combined, so that the uniformity of alloy components is effectively guaranteed, and the stability of the performance of the casting is improved; the reasonable casting process comprises proper casting temperature, casting mold preheating and a bottom pouring type casting mode, so that the defects of air holes, shrinkage porosity and the like are reduced, and the casting quality is improved.

Description

Technical Field

[0001] The invention relates to the technical field of metal casting, and in particular to a method for preparing a cobalt-based alloy casting. Background Art

[0002] Cobalt-based alloys are used in the aerospace field to manufacture key engine components, such as turbine blades, due to their superior high-temperature strength, excellent corrosion resistance and good wear resistance, to ensure stable operation in extremely high-temperature environments; in the medical field, they are often used to make artificial joints because of their good biocompatibility, which can reduce the body's rejection reaction; in the chemical industry, they can be used as corrosion-resistant pipe and reactor materials to cope with the erosion of complex chemical media, and are widely used.

[0003] However, the existing cobalt-based alloy casting preparation methods have many shortcomings that need to be addressed; from the perspective of process technology, traditional casting processes, such as sand casting and ordinary investment casting, have limited means to control the alloy composition. Taking sand casting as an example, the permeability and yield of the casting mold are difficult to accurately match the alloy solidification process, resulting in the distribution of various elements in the alloy liquid being easily disturbed by external factors during filling and solidification, and it is difficult to accurately control the uniformity of the alloy composition, which ultimately causes significant fluctuations in casting performance. The deviation of the mechanical performance indicators of the same batch of castings can reach 15%-20%;

[0004] During the casting process, the generation of pores and shrinkage defects seriously affects the quality of castings. On the one hand, during the smelting process, if the degassing process is not perfect, the alloy liquid will contain a large amount of gas. During the subsequent solidification, the gas cannot escape in time, thus forming pores. On the other hand, there is a large volume shrinkage during the solidification process of cobalt-based alloys. If the shrinkage feeding system is not designed properly, shrinkage is very likely to occur inside the casting. These defects greatly reduce the density of the casting and shorten the fatigue life of the casting by 30%-40%, seriously affecting its quality and reliability.

[0005] In addition, as the manufacturing industry continues to increase its requirements for cost control and production efficiency, the disadvantages of some preparation methods have become increasingly prominent. For example, some early vacuum casting processes, although they can improve the quality of castings to a certain extent, have extremely high energy consumption in equipment operation, and the power consumption of a single smelting process is 40%-50% higher than that of new energy-saving processes. At the same time, the lengthy process flow and complex operation links have led to a significant extension of the production cycle and low production efficiency, making it difficult to meet the urgent needs of large-scale industrial production for high efficiency and low cost.

[0006] Therefore, it is necessary to provide a method for preparing a cobalt-based alloy casting to solve the above technical problems. Summary of the invention

[0007] The present invention provides a method for preparing a cobalt-based alloy casting, which solves the problems of difficult to precisely control the alloy composition, easy to cause performance fluctuations; frequent occurrence of gas holes and shrinkage porosity in casting, reducing quality and reliability; high energy consumption and long process in some methods, unable to meet the industrial requirements of high efficiency and low cost.

[0008] To solve the above technical problems, a method for preparing a cobalt-based alloy casting provided by the present invention includes the following steps:

[0009] S1. Raw material preparation: Select raw materials with a cobalt content of 50-65%, a chromium content of 20-30%, a tungsten content of 5-15%, a nickel content of 3-8%, and a carbon content of 0.2-0.8% by mass percentage, and the rest are inevitable impurities. Pretreat the raw materials to remove surface oil stains, oxides and other impurities.

[0010] S2. Melting: Add the pretreated raw materials into a vacuum induction melting furnace and melt them under the condition of a vacuum degree of 10 3 -104 Pa. First, quickly raise the temperature at a higher power to melt the raw materials, and then reduce the power for 30-60 minutes of refining. During the melting process, use an electromagnetic stirring device to stir the alloy liquid.

[0011] S3. Casting: Heat the melted alloy liquid to 1500-1600 °C, and at the same time preheat the mold to 300-400 °C. Adopt the bottom gating casting method and inject the alloy liquid into the preheated mold at a casting speed of 1-3 kg / s.

[0012] S4. Cooling and heat treatment: After casting, the casting is naturally cooled in the mold to 800-900 °C, taken out and air-cooled to room temperature, then solution treatment is carried out, the solution temperature is 1100-1200 °C, and it is held for 2-4 hours. After that, aging treatment is carried out, the aging temperature is 700-800 °C, and it is held for 4-6 hours.

[0013] Preferably, the raw material pretreatment is specifically to ultrasonically clean the raw materials and dry them at 120 °C for 2 hours.

[0014] Preferably, in step S2, the rapid heating power is 100-120 kW, the melting time is 25-30 minutes, and the refining power is 50-60 kW.

[0015] Preferably, the stirring speed of the electromagnetic stirring device during refining is 200-250 r / min.

[0016] Preferably, the vacuum induction melting furnace used in the step S2 includes a furnace body, a top cover is arranged at the top of the furnace body, support frames are fixedly installed on both sides of the furnace body, sliding grooves are formed on both sides of the support frames, a transmission box is fixedly installed at the top of the support frames, a driving motor is fixedly installed on the front surface of the transmission box, a driving worm gear is fixedly installed at the output end of the driving motor, a first worm is engaged with the bottom of the driving worm gear, a rotating shaft is fixedly installed inside the first worm, second worms are fixedly installed at both ends of the outer side surface of the rotating shaft, a driven worm gear is engaged with one side of the second worms, a lead screw is fixedly installed inside the driven worm gear, the bottom of the lead screw is rotatably connected to the bottom of the inner side surface of the sliding groove, a connecting plate is threadedly connected to the outer side surface of the lead screw, a threaded rod is threadedly connected to the inside of the connecting plate, and the bottom of the threaded rod is rotatably connected to the top of the top cover.

[0017] Preferably, both ends of both sides of the connecting plate are respectively attached to both sides of the inner side surface of the sliding groove, two sliding rods are slidably connected to the inside of the connecting plate, and the bottoms of both sliding rods are fixedly installed on the top of the top cover.

[0018] Preferably, two support seats are rotatably connected to the outer side surface of the rotating shaft, and the support seats are fixedly installed on the inner side surface of the transmission box.

[0019] Preferably, a plurality of support feet are fixedly installed at the bottom of the furnace body, and a turning handle is fixedly installed at the top of the threaded rod.

[0020] Preferably, moving grooves are formed at both ends of the front surface of the support frame, a screw rod is slidably connected to the inner side surface of the moving groove, a gasket is sleeved on the outer side surface of the screw rod, a nut is arranged on the front surface of the gasket, and a rotating plate is fixedly installed on the front surface of the nut.

[0021] Preferably, the gasket is arranged on the front surface of the support frame, and the nut is threadedly connected to the outer side surface of the screw rod.

[0022] Compared with the related art, a preparation method of a cobalt-based alloy casting provided by the present invention has the following

[0023] Beneficial effects:

[0024] The present invention provides a preparation method of a cobalt-based alloy casting. By precisely controlling the raw material ratio and pretreatment, and melting under vacuum conditions and combining electromagnetic stirring, the uniformity of the alloy composition is effectively guaranteed, and the stability of the casting performance is improved;

[0025] A reasonable casting process, including a suitable casting temperature, mold preheating, and bottom gating casting method, reduces the generation of defects such as pores and shrinkage porosity, and improves the casting quality;

[0026] The optimized cooling and heat treatment processes improve the microstructure of the castings, further enhancing the mechanical properties of the castings. At the same time, the entire preparation process has low energy consumption and high production efficiency, which is conducive to large-scale industrial production. Description of the Drawings

[0027] Figure 1 It is a schematic flow diagram of a preferred embodiment of a method for preparing a cobalt-based alloy casting provided by the present invention;

[0028] Figure 2 It is a schematic structural diagram of a first embodiment of a vacuum induction melting furnace for a method for preparing a cobalt-based alloy casting provided by the present invention;

[0029] Figure 3 is Figure 1 The schematic top view sectional structure diagram of the transmission case shown;

[0030] Figure 4 is Figure 2 The enlarged schematic diagram of part A shown;

[0031] Figure 5 It is a schematic structural diagram of a second embodiment of a vacuum induction melting furnace for a method for preparing a cobalt-based alloy casting provided by the present invention;

[0032] Figure 6 is Figure 5 The enlarged schematic diagram of part B shown.

[0033] Reference numerals in the figure: 1, furnace body; 11, top cover; 12, support feet; 2, support frame; 21, sliding groove; 3, connecting plate; 31, threaded rod; 32, turning handle; 33, sliding rod; 4, transmission case; 41, drive motor; 42, driving worm gear; 43, first worm; 44, rotating shaft; 45, second worm; 46, driven worm gear; 47, lead screw; 48, support seat; 5, moving groove; 6, screw; 61, gasket; 62, nut; 63, rotating plate. Detailed Embodiments

[0034] The present invention will be further described below with reference to the drawings and embodiments.

[0035] First Embodiment

[0036] Please refer to Figure 1 , Figure 2 , Figure 3 , Figure 4 , wherein Figure 1 is a schematic flow diagram of a preferred embodiment of a method for preparing a cobalt-based alloy casting provided by the present invention; Figure 2 is a schematic structural diagram of a first embodiment of a vacuum induction melting furnace for a method for preparing a cobalt-based alloy casting provided by the present invention;

[0037] Figure 3 is Figure 1 a schematic top view sectional structure diagram of the transmission case shown; Figure 4 is Figure 2 a schematic enlarged view of part A shown. A preparation method of a cobalt-based alloy casting includes the following steps:

[0038] S1. Raw material preparation: According to mass percentage, select raw materials with a cobalt content of 50 - 65%, a chromium content of 20 - 30%, a tungsten content of 5 - 15%, a nickel content of 3 - 8%, and a carbon content of 0.2 - 0.8%, and the rest are inevitable impurities. Pretreat the raw materials to remove surface oil stains, oxides and other impurities;

[0039] S2. Melting: Add the pretreated raw materials into a vacuum induction melting furnace, melt under the condition of a vacuum degree of 10 3 -104 Pa. First, rapidly heat up with a higher power to melt the raw materials, and then reduce the power for 30 - 60 minutes of refining. During the melting process, use an electromagnetic stirring device to stir the alloy liquid;

[0040] S3. Casting: Heat up the melted alloy liquid to 1500 - 1600 °C, and at the same time preheat the mold to 300 - 400 °C. Adopt the bottom-pouring casting method and pour the alloy liquid into the preheated mold at a casting speed of 1 - 3 kg / s;

[0041] S4. Cooling and heat treatment: After casting, the casting is naturally cooled in the mold to 800 - 900 °C, taken out and air-cooled to room temperature, then solution treatment is carried out, the solution temperature is 1100 - 1200 °C, and it is kept warm for 2 - 4 hours. After that, aging treatment is carried out, the aging temperature is 700 - 800 °C, and it is kept warm for 4 - 6 hours.

[0042] The specific pretreatment of the raw materials is to ultrasonically clean the raw materials and dry them at 120 °C for 2 hours.

[0043] In the step S2, the rapid heating-up power is 100 - 120 kW, the melting time is 25 - 30 minutes, and the refining power is 50 - 60 kW.

[0044] The stirring speed of the electromagnetic stirring device during refining is 200 - 250 r / min.

[0045] The vacuum induction melting furnace used in the step S2 includes a furnace body 1. A top cover 11 is provided at the top of the furnace body 1. Support frames 2 are fixedly installed on both sides of the furnace body 1. Slide grooves 21 are formed on both sides of the support frame 2. A transmission box 4 is fixedly installed at the top of the support frame 2. A driving motor 41 is fixedly installed on the front of the transmission box 4. A driving worm gear 42 is fixedly installed at the output end of the driving motor 41. A first worm 45 is engaged with the bottom of the driving worm gear 42. A rotating shaft 44 is fixedly installed inside the first worm 45. Second worms 45 are fixedly installed at both ends of the outer side of the rotating shaft 44. A driven worm gear 46 is engaged with one side of the second worm 45. A lead screw 47 is fixedly installed inside the driven worm gear 46. The bottom of the lead screw 47 is rotatably connected to the bottom of the inner side of the slide groove 21. A connecting plate 3 is threadedly connected to the outer side of the lead screw 47. A threaded rod 31 is threadedly connected inside the connecting plate 3. The bottom of the threaded rod 31 is rotatably connected to the top of the top cover 11.

[0046] Both ends of both sides of the connecting plate 3 are respectively attached to both sides of the inner side of the slide groove 21. Two slide rods 33 are slidably connected inside the connecting plate 3. The bottoms of the two slide rods 33 are fixedly installed on the top of the top cover 11.

[0047] Two support seats 48 are rotatably connected to the outer side of the rotating shaft 44. The support seats 48 are fixedly installed on the inner side of the transmission box 4.

[0048] A plurality of support feet 12 are fixedly installed at the bottom of the furnace body 1. A turning handle 32 is fixedly installed at the top of the threaded rod 31.

[0049] When in use, when it is necessary to open the top cover 11 on the top of the furnace body 1, the user starts the driving motor 41, so that the driving motor 41 drives the driving worm gear 42 to rotate, so that the driving worm gear 42 meshes with the first worm 43, and then drives the rotating shaft 44 to rotate. Then, the second worm 45 drives the driven worm gear 46 to rotate. Then, the driven worm gear 46 drives the lead screw 47 to be threadedly connected inside the connecting plate 3, so as to move the top cover 11 away from the top of the furnace body 1, which is convenient for the user to remove the top cover 11.

[0050] When it is necessary to move the top cover 11 to the top of the furnace body 1, the driving motor 41 can be reversed to move the top cover 11 to the top of the furnace body 1. Then, the turning handle 32 is rotated again. Then, the turning handle 32 drives the threaded rod 31 to be threadedly connected inside the connecting plate 3, so that the top cover 11 is tightly pressed against the top of the furnace body 1 to increase the sealing performance.

[0051] Compared with the related technologies, a preparation method of a cobalt-based alloy casting provided by the present invention has the following

[0052] Beneficial effects:

[0053] By precisely controlling the raw material ratio and pretreatment, melting under vacuum conditions and combining electromagnetic stirring, the uniformity of the alloy composition is effectively ensured, and the stability of the casting performance is improved;

[0054] A reasonable casting process, including a suitable casting temperature, mold preheating, and bottom-pouring casting method, reduces the generation of defects such as pores and shrinkage porosity, and improves the casting quality;

[0055] The optimized cooling and heat treatment process improves the microstructure of the casting, further enhances the mechanical properties of the casting. At the same time, the entire preparation process has low energy consumption and high production efficiency, which is conducive to large-scale industrial production.

[0056] Second Embodiment

[0057] Please refer to Figure 5 and Figure 6 Based on a preparation method of a cobalt-based alloy casting provided in the first embodiment of the present application, the second embodiment of the present application proposes another preparation method of a cobalt-based alloy casting. The second embodiment is only a preferred manner of the first embodiment, and the implementation of the second embodiment will not affect the independent implementation of the first embodiment.

[0058] Specifically, the difference of a preparation method of a cobalt-based alloy casting provided in the second embodiment of the present application is that in a preparation method of a cobalt-based alloy casting, both ends of the front surface of the support frame 2 are provided with moving grooves 5, the inner side surface of the moving groove 5 is slidably connected with a screw rod 6, a gasket 61 is sleeved on the outer side surface of the screw rod 6, a nut 62 is arranged on the front surface of the gasket 61, and a rotating plate 63 is fixedly installed on the front surface of the nut 62.

[0059] The gasket 61 is arranged on the front surface of the support frame 2, and the nut 62 is threadedly connected to the outer side surface of the screw rod 6.

[0060] The working principle of a preparation method of a cobalt-based alloy casting provided by the present invention is as follows:

[0061] When in use, after moving the connecting plate 3 to a suitable position, the user can rotate the nut 62, so that the nut 62 is threadedly connected to the outer side surface of the screw rod 6, so that the gasket 61 abuts against the front surface of the support frame 2, so as to play a role in limiting the connecting plate 3.

[0062] Compared with the related technologies, a preparation method of a cobalt-based alloy casting provided by the present invention has the following

[0063] Beneficial effects:

[0064] Through the cooperation of structures such as the moving groove 5, the screw 6, the gasket 61, the nut 62 and the rotating plate 63, when in use, the nut 62 can be threadedly connected to the outer side of the screw 6, so that one side of the gasket 61 can abut against the front surface of the support frame 2, thereby increasing the stability of the connecting plate 3.

[0065] The above are only embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A method for preparing a cobalt-based alloy casting, characterized in that, It includes the following steps: S1. Raw material preparation: Select raw materials with a cobalt content of 50 - 65%, a chromium content of 20 - 30%, a tungsten content of 5 - 15%, a nickel content of 3 - 8%, and a carbon content of 0.2 - 0.8% by mass percentage, with the rest being inevitable impurities. Pretreat the raw materials to remove impurities such as surface oil stains and oxides; S2. Melting: Add the pretreated raw materials into a vacuum induction melting furnace and melt them under the condition of a vacuum degree of 10 3 -104 Pa. First, rapidly heat up to melt the raw materials at a higher power, and then reduce the power for 30 - 60 minutes of refining. During the melting process, use an electromagnetic stirring device to stir the alloy liquid; S3. Casting: Heat the melted alloy liquid to 1500 - 1600 °C, and at the same time preheat the mold to 300 - 400 °C. Adopt the bottom - pouring casting method and pour the alloy liquid into the preheated mold at a casting speed of 1 - 3 kg / s; S4. Cooling and heat treatment: After casting, the casting is naturally cooled in the mold to 800 - 900 °C, taken out and air - cooled to room temperature, then solution treatment is carried out. The solution temperature is 1100 - 1200 °C and the holding time is 2 - 4 hours. After that, aging treatment is carried out. The aging temperature is 700 - 800 °C and the holding time is 4 - 6 hours.

2. The preparation method of a cobalt-based alloy casting according to claim 1, wherein The specific raw material pretreatment is to ultrasonically clean the raw materials and dry them at 120 °C for 2 hours.

3. The preparation method of a cobalt-based alloy casting according to claim 1, characterized in that, In step S2, the rapid heating power is 100 - 120 kW, the melting time is 25 - 30 minutes, and the refining power is 50 - 60 kW.

4. The preparation method of a cobalt-based alloy casting according to claim 1, characterized in that, The stirring speed of the electromagnetic stirring device during the refining process is 200 - 250 r / min.

5. A method for preparing a cobalt-based alloy casting according to claim 1, characterized in that, The vacuum induction melting furnace used in step S2 includes a furnace body. A top cover is arranged at the top of the furnace body. Support frames are fixedly installed on both sides of the furnace body. Sliding grooves are opened on both sides of the support frame. A transmission box is fixedly installed on the top of the support frame. A driving motor is fixedly installed on the front of the transmission box. A driving worm gear is fixedly installed at the output end of the driving motor. A first worm is engaged with the bottom of the driving worm gear. A rotating shaft is fixedly installed inside the first worm. Second worms are fixedly installed at both ends of the outer side of the rotating shaft. A driven worm gear is engaged with one side of the second worm. A lead screw is fixedly installed inside the driven worm gear. The bottom of the lead screw is rotatably connected to the bottom of the inner side of the sliding groove. A connecting plate is threadedly connected to the outer side of the lead screw. A threaded rod is threadedly connected to the inside of the connecting plate. The bottom of the threaded rod is rotatably connected to the top of the top cover.

6. The preparation method of a cobalt-based alloy casting according to claim 5, characterized in that, Both ends of both sides of the connecting plate are respectively attached to both sides of the inner side of the sliding groove. Two sliding rods are slidably connected to the inside of the connecting plate. The bottoms of both sliding rods are fixedly installed on the top of the top cover.

7. The preparation method of a cobalt-based alloy casting according to claim 6, characterized in that, Two support seats are rotatably connected to the outer side of the rotating shaft. The support seats are fixedly installed on the inner side of the transmission box.

8. A method for preparing a cobalt-based alloy casting according to claim 5, characterized in that, A plurality of support feet are fixedly installed at the bottom of the furnace body. A turning handle is fixedly installed at the top of the threaded rod.

9. The preparation method of a cobalt-based alloy casting according to claim 5, characterized in that, Moving grooves are opened at both ends of the front of the support frame. Screws are slidably connected to the inner sides of the moving grooves. Gaskets are sleeved on the outer sides of the screws. Nuts are arranged on the fronts of the gaskets. Rotating plates are fixedly installed on the fronts of the nuts.

10. The preparation method of a cobalt-based alloy casting according to claim 9, characterized in that, The gaskets are arranged on the front of the support frame. The nuts are threadedly connected to the outer sides of the screws.

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