Preparation method of high-homogeneity GH5188 alloy powder suitable for additive manufacturing

Abstract

The invention relates to a preparation method of high-homogeneity GH5188 alloy powder suitable for additive manufacturing, and relates to the technical field of metal powder preparation.The preparation method comprises the following steps that a GH5188 master alloy ingot is subjected to triple smelting, and a high-homogeneity master alloy ingot is obtained; rolling and processing to obtain an alloy bar; the alloy bar is subjected to crucible-free electrode induction melting and mixed gas atomization treatment, mixed gas comprises Ar and CO, and powder is obtained; and screening treatment is conducted, and the high-homogeneity GH5188 alloy powder with the target particle size is obtained. A triple master alloy smelting process is adopted, a high-homogeneity master alloy material is obtained, the problem of component fluctuation is solved from the source, crucible-free electrode induction gas atomization is combined, component burning loss and inclusion formation in the process are avoided, precise component control is achieved, high-purity Ar and CO mixed gas is adopted for atomization, and the high-purity Ar and CO mixed gas atomization effect is achieved. And the oxygen increasing problem of the powder in the circulating gas atomization process is reduced, and the uniformity and stability of metal powder components are effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal powder preparation, in particular to a high-homogeneity GH5188 alloy powder preparation method suitable for additive manufacturing. BACKGROUND

[0002] Additive manufacturing technology (also known as "3D printing technology" or "rapid prototyping technology") is a new technology developed in the past 30 years based on the principle of discrete accumulation, which manufactures parts through layer-by-layer accumulation of materials. The mainstream processes such as powder bed fusion, direct energy deposition and binder jetting all use metal powder as the key raw material. GH5188 alloy, as a solid solution strengthening cobalt-based superalloy, is known for its excellent yield strength, tensile strength, processing and welding performance, and outstanding high-temperature oxidation resistance, and is particularly suitable for additive manufacturing of key structural parts such as aircraft engine cooling rings, turbine engine combustion chambers and fuel nozzles, which need to serve in high-temperature environment for a long time and withstand instantaneous high temperature and gas scouring.

[0003] Currently, the mainstream preparation methods of GH5188 alloy powder include vacuum induction melting gas atomization (VIGA) and plasma rotating electrode process (PREP). VIGA melts the alloy raw material in a vacuum environment, and then uses high-speed gas to break the molten metal stream into powder. PREP relies on the plasma arc to melt the end of the high-speed rotating alloy electrode rod, and the molten metal droplets are thrown out under the action of centrifugal force and solidified into powder.

[0004] However, these existing technical means have obvious defects. For vacuum induction melting atomization VIGA, due to the high activity of La, it is easy to react with oxygen, sulfur and other elements in the steel liquid during crucible melting, or combine with the oxygen on the crucible wall to generate La2O3 and La2S3, resulting in a large amount of burning loss, causing large fluctuations in the La powder produced in the same furnace, and the La2O3 and La2S3 produced in the same furnace. Part of the La2O3 and La2S3 falls off from the crucible wall and mixes into the powder with the steel liquid to become inclusions. The plasma rotating electrode method has low fine powder yield due to its own technical limitations, the remaining material cannot be atomized, and the electrode rod material has high machining precision, which indirectly leads to an increase in the cost of the powder, and therefore needs to be improved. SUMMARY

[0005] In order to improve the performance of GH5188 alloy powder, the present application provides a high-homogeneity GH5188 alloy powder preparation method suitable for additive manufacturing.

[0006] The high-homogeneity GH5188 alloy powder preparation method suitable for additive manufacturing provided by the present application adopts the following technical scheme: A high-homogeneity GH5188 alloy powder preparation method suitable for additive manufacturing includes the following steps: S1, triple smelting is performed on the GH5188 master alloy ingot to obtain a high homogenization master alloy ingot; the triple smelting includes vacuum induction melting, first vacuum consumable remelting, and second vacuum consumable remelting; S2, the high homogenization master alloy ingot is rolled and processed to obtain an alloy rod; S3, the alloy rod is processed by adopting crucible-free electrode induction melting and mixed gas atomization treatment, the mixed gas including Ar and CO, to obtain a powder; S4, the powder is subjected to screening treatment to obtain a high homogenization GH5188 alloy powder with a target particle size.

[0007] The triple smelting process is used to realize deep homogenization of the master alloy ingot, and the vacuum induction melting combined with the two-step vacuum consumable remelting effectively reduces element segregation and improves the density of the master alloy; the crucible-free electrode induction melting combined with the gas atomization technology avoids the pollution of the crucible material, refines the microstructure through rapid solidification, and suppresses element segregation, thereby forming an alloy powder with uniform distribution; and the final screening treatment makes the powder particle size distribution meet the requirements of additive manufacturing; the above preparation process realizes multi-stage coordination from the purity of the master alloy ingot, the impurity control in the melting process, to the rapid solidification regulation, thereby improving the chemical uniformity of the powder, helping to improve the organization consistency and performance stability of the additive manufacturing parts, and thus ensuring the reliability of the material performance.

[0008] Preferably, the triple smelting in step S1 includes the following steps: (1) Vacuum induction melting: Co, Cr, Ni, W, Fe, La and other raw materials are added according to the composition ratio of the GH5188 alloy, the La addition amount is 1-10 times the target value, and after melting, the alloy ingot I with a diameter of 100-250 mm and a length of 650-1500 mm is cast in a mold; (2) First vacuum consumable remelting: the oxide slag on the surface of the alloy ingot I is cleaned, and the composition is detected to determine the content of La; after the content of La is supplemented to the target content, 2-5 alloy ingots are welded end to end to form a long electrode I for first vacuum consumable remelting to obtain an alloy ingot II; (3) Second vacuum consumable remelting: the oxide slag and the riser on the surface of the alloy ingot II are cleaned, and the alloy ingot II is welded end to end to form a long electrode II for second vacuum consumable remelting to obtain a high homogenization master alloy ingot.

[0009] The first vacuum induction melting is added with excess volatile elements to ensure the total amount of elements; the subsequent two vacuum consumable remelting forms step-by-step improvement of uniformity, the first remelting is supplemented according to the measured value, the second remelting is further improved in uniformity by means of electromagnetic stirring, and the long electrode remelting mode is used to improve the axial consistency of the ingot.

[0010] Preferably, the vacuum induction melting in step (1) is refined at 1500-1600 ℃ for 20-40 min, the vacuum degree is ≤10 Pa, argon is filled to 0.5-0.6 bar for pressure maintaining, and casting is carried out at 1500-1550 ℃ into a preheated mold at 300-500 ℃.

[0011] In the high-temperature refining stage, sufficient thermal kinetic conditions are created to promote the decomposition of inclusions and the removal of gas, and the high-vacuum environment effectively reduces the oxygen content of the melt; then the temperature-controlled casting under inert atmosphere protection is carried out to inhibit the escape of volatile elements and avoid secondary oxidation of the melt, and the preheated mold slows down the solidification rate to reduce the shrinkage tendency; the above process parameters strengthen the purity of the melt while ensuring the density of the solidification structure of the ingot.

[0012] Preferably, the first vacuum consumable remelting in step (2) is remelted at a vacuum degree of ≤1.0 Pa, the melting current is 6-12 kA, the voltage is 25-35 V, the melting rate is 10-15 kg / min, the cooling water pressure is 0.7-1.0 MPa, and the flow rate is 300-500 L / min; the current is reduced to 30% in stages during the arc collection stage and maintained for 5-15 min.

[0013] The deep vacuum environment strengthens the effects of melt degassing and impurity volatilization, the controlled current and voltage combination maintains a stable arc shape, the melt pool maintains a reasonable depth-width ratio to promote the floating separation of inclusions, a specific melting rate matches the cooling intensity, and the microstructure arrangement is optimized; the stepwise current decay strategy is adopted in the arc collection stage to simultaneously reduce the solidification shrinkage stress and melt disturbance, and the formation of top loose defects is inhibited; the above dynamic process design takes into account the melt purification and solidification structure control during the continuous growth of the ingot, and provides a low-impurity melt with axial structural continuity for the second remelting.

[0014] Preferably, the second vacuum consumable remelting in step (3) is remelted at a vacuum degree of ≤1.0 Pa, the melting current is 10-30 kA, the voltage is 25-35 V, and the melting rate is 15-25 kg / min; the depth of the melt pool is controlled to be 1 / 3 of the diameter of the ingot, the cooling water pressure is 0.8-1.2 MPa, the flow rate is 350-550 L / min, and the cooling rate is 10-30 ℃ / min.

[0015] The secondary vacuum consumable remelting optimizes the dynamic balance of energy input and cooling intensity by the synergistic effect of vacuum environment and thermodynamic parameters, maintains the reasonable depth of the molten pool, and promotes the formation of stable axial temperature gradient in the solidification process, thereby strengthening the diffusion homogenization ability of solute elements at the solid-liquid interface and inhibiting local segregation tendency.

[0016] Preferably, the diameter of the high-homogeneous master alloy ingot is changed by one-step direct rolling in step S2 to obtain a rough bar with a processing allowance of 0.5-5 mm; the rough bar is segmented according to a fixed size of 680-1080 mm to obtain an alloy bar with a diameter of 80-150 mm.

[0017] The appropriate processing allowance is reserved to compensate for the size fluctuation in the hot deformation process, thereby ensuring the precision of subsequent finishing; the segmentation design of a specific length specification takes into account the clamping stability of electrode melting and the material utilization rate; the plastic rheology generated by direct rolling synchronously refines the as-cast grains and fills the micro defects; the cooperation of the geometric size control and the microstructure evolution regulation enables the alloy bar to have the structural characteristics of high surface regularity and uniform internal structure, thereby providing an electrode material basis with stable electrical conductivity and thermal conductivity for the induction melting of the crucible-free electrode.

[0018] Preferably, the electrode induction melting conditions in step S3 are as follows: the alloy bar is continuously melted at the end portion under a protective atmosphere at a temperature of 1550-1650 °C to obtain a molten metal liquid.

[0019] The inert atmosphere can effectively isolate the molten metal from oxygen and nitrogen and inhibit the volatilization loss of elements; the continuous melting mode in the above temperature range maintains the stable transition of the metal droplet and ensures the consistency of the melt composition transmission; the non-contact melting mechanism avoids the contamination of the crucible material, thereby enabling the molten liquid to have a stable thermophysical state and chemical homogeneity, and providing a melt basis with controllable flowability and composition stability for subsequent gas atomization.

[0020] Preferably, the mixed gas atomization treatment in step S3 is performed by atomizing the molten metal liquid with a mixed gas, and the volume fraction of CO in the mixed gas is 0.1%-10%.

[0021] CO forms a surface adsorption layer in the high-temperature atomization field, moderately reduces the surface tension of the melt to promote the uniform dispersion of the droplets; at the same time, its reducing property inhibits the generation of an oxidation film on the surface of the droplets, and cooperates with the inert gas base medium to ensure the cleanliness of the rapid solidification process; the above-mentioned synergistic effect of the gas components optimizes the atomization efficiency while maintaining the spheroidization effect of the droplets, which is helpful to obtain pre-alloyed powder with a smooth surface, high sphericity and controllable oxygen increment, thereby providing a raw material basis with good flowability and low satellite powder tendency for additive manufacturing.

[0022] Preferably, the mixing gas atomization treatment in step S3 is under the conditions of atomization pressure 6-8 MPa, gas flow rate 300-500 m / s, and gas-liquid ratio 15-25 m 3 / kg.

[0023] The atomization pressure and gas flow rate combination forms a high kinetic energy turbulent flow field, improves the melt breaking efficiency and refines the melt droplet size distribution; the gas-liquid ratio ensures sufficient heat conduction conditions, promotes uniform solidification of the melt droplets to inhibit the formation of coarse dendritic structure; the parameters cooperate to make the powder simultaneously achieve particle size concentrated distribution and internal microstructure refinement, providing a raw material basis with good sphericity and consistent physical properties for additive manufacturing.

[0024] Preferably, the purity of the mixed gas before use is ≥99.999%, and the gas is uniformly mixed for 40-50 min without material empty cycle. The atomized gas is recycled after condensation and filtration of dust.

[0025] The ultra-high purity gas source minimizes the risk of introducing external impurities, and the pre-circulation treatment promotes the full homogenization of the gas components, ensuring the stability of the atomization flow field; the waste gas purification and recycling mechanism simultaneously maintains the constant gas components and the impurity concentration threshold, forming a closed-loop self-cleaning system, which continuously optimizes the atomization heat exchange efficiency while preventing secondary pollution of the powder surface composition and internal structure.

[0026] Preferably, in the screening step S4, the screening is performed by a combination of vibration screening and airflow classification under a protective atmosphere.

[0027] In summary, the present application includes at least one of the following beneficial technical effects: 1. Using triple smelting GH5188 master alloy ingot can obtain alloy bar with accurate La content and uniform composition. Combined with crucible-free electrode induction melting and mixed gas atomization, the oxygen content of the powder is reduced, significantly improving the controllability and uniformity of the powder composition. The material utilization rate is high throughout the process, meeting the urgent need for high-quality GH5188 alloy powder in China, and improving the reliability of aerospace equipment.

[0028] 2. Crucible-free electrode induction melting avoids secondary burning loss caused by crucible in subsequent smelting and atomization steps, and avoids contamination and burning loss of the powder; the use of circulating gas reduces gas consumption during atomization. By introducing a small amount of strong reducing CO gas, the oxygen content of the atomized powder is reduced, thereby preparing low-oxygen alloy powder and improving the number of times the powder can be reused during 3D printing. DETAILED DESCRIPTION

[0029] The application discloses a preparation method of a high-homogeneity GH5188 alloy powder suitable for additive manufacturing. The raw materials used in the application can be obtained from commercially available raw materials, except for special instructions. The application is further described in detail in combination with the embodiments. Embodiment 1 S1, triple smelting is performed on the GH5188 master alloy ingot: (1) vacuum induction melting: ingredients are prepared according to the chemical composition of the GH5188 alloy, and high-purity Co pieces, Cr pieces, Ni pieces, W strips, Fe particles, nickel-boron intermediate alloy and other raw materials are fed and melted. After the main materials are melted, La and other trace elements are fed, the target value of La is 0.060%, the introduction amount of La is 0.25%, and the refining is performed at 1500°C for 40 min under a vacuum degree of ≤10 Pa. Argon is filled to 0.5 bar for pressure maintaining, and casting is performed at 1500°C into a preheated 300°C steel mold, obtaining an alloy ingot I with a diameter of 160 mm and a length of 1000 mm; (2) first vacuum consumable remelting: the oxide slag on the surface of the alloy ingot I is cleaned, the La content is detected by sampling the upper, middle and lower positions of the alloy ingot I, and the La content of each ingot is supplemented to 0.060% by rotating the ingot along the axial direction and uniformly interval punching and inserting nickel lanthanum intermediate alloy. Four alloy ingots are welded end to end to form a long electrode I for first vacuum consumable remelting, and the remelting is performed under a vacuum degree of ≤1.0 Pa, a melting current of 6 kA, a voltage of 25 V, a melting rate of 10 kg / min, a cooling water pressure of 0.7 MPa and a flow rate of 300 L / min. The current is reduced to 30% in stages during the arc recovery stage and maintained for 5 min, obtaining an alloy ingot II with a diameter of 230 mm; (3) second vacuum consumable remelting: the oxide slag on the surface of the alloy ingot II is cleaned, the riser is cut off, and two alloy ingots II are welded end to end to form a long electrode II for second vacuum consumable remelting. The remelting is performed under a vacuum degree of ≤1.0 Pa, a melting current of 10 kA, a voltage of 25 V and a melting rate of 15 kg / min. The depth of the molten pool is controlled to be 1 / 3 of the diameter of the ingot, the cooling water pressure is 0.8 MPa, the flow rate is 350 L / min, and the cooling rate is 10°C / min, obtaining a high-homogeneity master alloy ingot with a diameter of 320 mm.

[0030] S2, after the surface of the high-homogeneity master alloy ingot is cleaned, the diameter is changed by first direct rolling, heated to 1220°C, and rolled after holding for 200 min. The diameter of the raw bar after rolling is 83.5 mm. The raw bar is divided according to the fixed size of 950 mm, and the surface is turned to remove the skin and finely ground to an alloy bar with a diameter of 81.5 mm.

[0031] S3. The alloy rod is melted using a crucibleless electrode induction melting process at 1550℃ under an argon protective atmosphere, allowing the tip of the alloy rod to continuously melt and obtain molten metal. The molten metal is then subjected to mixed gas atomization treatment. The mixed gas includes Ar and CO, with a purity ≥99.999% before use and a CO volume percentage of 1.5%. The mixture is first circulated without material for 45 minutes using a gas circulation system. The atomization pressure is 6 MPa, the gas flow rate is 300 m / s, and the gas-liquid ratio is 15 m / s. 3 / kg, to obtain powder (A0); the atomized gas is condensed, purified, and filtered for dust before being recycled.

[0032] S4. The powder is sieved through 100 mesh and 250 mesh sieves. Powders of -100 mesh and +250 mesh are taken and the particle size distribution is adjusted by airflow classification to obtain high-homogeneity GH5188 alloy powder (A1) with a particle size range of 58-150μm, which is used in electron beam melting and energy deposition additive manufacturing. Powder of -250 mesh is taken and the particle size distribution is adjusted by airflow classification to obtain high-homogeneity GH5188 alloy powder (A2) with a particle size range of 15-53μm. The finished powder is used in selective laser melting.

[0033] Example 2 (1) Vacuum induction melting: According to the chemical composition of GH5188 alloy, the raw materials such as high-purity Co flakes, Cr flakes, Ni flakes, W strips, Fe granules, and nickel-boron master alloy are fed and melted. After the main material is melted, La and other trace elements are added. The target value of La is 0.050%, and the amount of La introduced is 0.2%. The material is refined at 1600℃ for 20 minutes with a vacuum degree ≤10Pa. Argon gas is charged to 0.6 bar and held at 1550℃. The material is then cast into a preheated steel mold at 500℃ to obtain alloy round ingot I with a diameter of 160mm and a length of 1000mm. (2) Vacuum self-consumption remelting: Clean the oxide slag on the surface of alloy ingot I, take samples from the upper, middle and lower positions of alloy ingot I to test the La content, rotate each ingot along the axial direction to make holes at uniform intervals, insert nickel-lanthanum master alloy, and supplement the La content of each ingot to 0.050%. Weld the five alloy ingots together to form long electrode I and perform vacuum self-consumption remelting. Remelting is carried out under vacuum degree ≤1.0Pa, melting current 12kA, voltage 35V, melting rate 15kg / min, cooling water pressure 1MPa, flow rate 500L / min; during the arc termination stage, the current is reduced to 30% in stages and maintained for 15min to obtain alloy ingot II with a diameter of 250mm. (3) Secondary vacuum consumable remelting: cleaning the surface of the alloy ingot II of the oxidized slag, cutting off the riser, and welding two alloy ingots II end to end into a long electrode II for secondary vacuum consumable remelting, remelting under a vacuum degree of ≤1.0 Pa, a melting current of 30 kA, a voltage of 35 V, and a melting rate of 25 kg / min; the depth of the molten pool is controlled to be 1 / 3 of the diameter of the ingot, the cooling water pressure is 1.2 MPa, the flow rate is 550 L / min, the cooling rate is 30℃ / min, and a high-homogeneity master alloy ingot with a diameter of 380 mm is obtained.

[0034] S2, after the high-homogeneity master alloy ingot is cleaned of slag on the surface, the diameter is changed by one-time direct rolling, heating to 1220℃, holding for 220 min, and then rolling, and the diameter of the raw bar after rolling is 92 mm; the raw bar is cut according to a fixed size of 950 mm, the surface is turned and scraped, and the alloy bar with a diameter of 90 mm is obtained by fine grinding.

[0035] S3, the alloy bar is subjected to electrode induction melting without a crucible, is continuously melted at 1650℃ in an argon protective atmosphere, and a molten metal liquid is obtained; the molten metal liquid is subjected to mixed gas atomization treatment, the mixed gas includes Ar and CO, the purity of the mixed gas before use is ≥99.999%, the volume ratio of CO in the mixed gas is 1.5%, the gas circulation system is first used for air circulation without material for 45 min, the atomization pressure is 8 MPa, the gas flow rate is 500 m / s, the gas-liquid ratio is 25 m 3 / kg, and a powder (A0) is obtained; the atomized gas is recycled after being condensed and filtered.

[0036] S4, the powder is subjected to screening treatment, is screened through 100 mesh and 250 mesh, the -100 mesh and +250 mesh powders are taken, the particle size distribution is adjusted by airflow classification, a high-homogeneity GH5188 alloy powder with a particle size of 58-150μm (A1) is obtained, and is applied to electron beam melting and energy deposition type additive manufacturing; the -250 mesh powder is taken, the particle size distribution is adjusted by airflow classification, a high-homogeneity GH5188 alloy powder with a particle size of 15-53μm (A2) is obtained, and the finished powder is applied to selective laser melting.

[0037] Example 3 S1, the GH5188 master alloy ingot is subjected to triple smelting: (1) Vacuum induction melting: ingredients are prepared according to the chemical composition of GH5188 alloy, high-purity Co sheet, Cr sheet, Ni sheet, W strip, Fe particle, nickel-boron intermediate alloy and other raw materials are fed and melted, after the main material is melted, La and other trace elements are fed, the target value of La is 0.060%, the introduction amount of La is 0.25%, refining is carried out at 1550°C for 30min, the vacuum degree is ≤10Pa; argon is filled to 0.55bar to maintain pressure, and casting is carried out at 1525°C into a preheated 400°C steel mold, obtaining alloy ingot I with a diameter of 160mm and a length of 1000mm; (2) First vacuum consumable remelting: the oxide slag on the surface of the alloy ingot I is cleaned, the La content is detected by sampling the upper, middle and lower positions of the alloy ingot I, each ingot is uniformly and interval punched along the axial direction, nickel lanthanum intermediate alloy is inserted, the La content of each ingot is supplemented to 0.060%, four alloy ingots are welded end to end to form a long electrode I for first vacuum consumable remelting, remelting is carried out under a vacuum degree of ≤1.0Pa, the melting current is 9kA, the voltage is 30V, the melting rate is 12.5kg / min, the cooling water pressure is 0.85MPa, and the flow is 400L / min; the current is reduced to 30% in stages during the arc collection stage and maintained for 10min, obtaining alloy ingot II with a diameter of 230mm; (3) Second vacuum consumable remelting: the oxide slag on the surface of the alloy ingot II is cleaned, the riser is cut off, two alloy ingots II are welded end to end to form a long electrode II for second vacuum consumable remelting, remelting is carried out under a vacuum degree of ≤1.0Pa, the melting current is 20kA, the voltage is 30V, and the melting rate is 20kg / min; the depth of the molten pool is controlled to be 1 / 3 of the diameter of the ingot, the cooling water pressure is 1MPa, the flow is 450L / min, the cooling rate is 20°C / min, and a high-homogeneity master alloy ingot with a diameter of 320mm is obtained.

[0038] S2, after the high-homogeneity master alloy ingot is cleaned of surface slag, the diameter is changed by first direct rolling, heated to 1220°C, and rolled after holding for 200min, the diameter of the raw bar after rolling is 83.5mm; the raw bar is divided according to the fixed size of 950mm, the surface is turned to remove the skin, and the alloy bar with a diameter of 81.5mm is obtained by fine grinding.

[0039] S3, the alloy bar is melted by electrode induction melting without a crucible, the end of the alloy bar is continuously melted at 1600°C in an argon protective atmosphere to obtain molten metal liquid; the molten metal liquid is treated by mixed gas atomization, the mixed gas includes Ar and CO, the purity of the mixed gas before use is ≥99.999%, the volume ratio of CO in the mixed gas is 1.5%, the gas circulation system is first circulated for 45min without material, the atomization pressure is 7MPa, the gas flow rate is 400m / s, the gas-liquid ratio is 20m 3 / kg, to obtain powder (A0); the gas after atomization is recycled after being condensed to remove impurities and filtered dust.

[0040] S4, the powder is sieved, sieved through 100 mesh and 250 mesh, -100 mesh and +250 mesh powders are taken, the particle size distribution is adjusted by air flow classification, to obtain high-homogeneity GH5188 alloy powder in the particle size range of 58-150 pm (A1) which is applied to electron beam melting and energy deposition type additive manufacturing; -250 mesh powder is taken, the particle size distribution is adjusted by air flow classification, to obtain high-homogeneity GH5188 alloy powder in the particle size range of 15-53 pm (A2), the finished powder is applied to selective laser melting.

[0041] Example 4 Example 4 is based on Example 1, and the only difference between Example 4 and Example 1 is that in Example 4, in step S1, (1) the vacuum induction melting conditions are refining at 1450℃ for 50 min, vacuum degree ≤10 Pa; argon is filled to 0.45 bar for pressure maintaining, and casting is performed at 1450℃ into a preheated steel mold at 250℃.

[0042] Example 5 Example 5 is based on Example 1, and the only difference between Example 5 and Example 1 is that in Example 5, in step S1, (1) the vacuum induction melting conditions are refining at 1650℃ for 10 min, vacuum degree ≤10 Pa; argon is filled to 0.65 bar for pressure maintaining, and casting is performed at 1600℃ into a preheated steel mold at 600℃.

[0043] Example 6 Example 6 is based on Example 1, and the only difference between Example 6 and Example 1 is that in Example 6, in step S1, (2) the conditions of the first vacuum consumable remelting are remelting at a vacuum degree ≤1.0 Pa, melting current 4 kA, voltage 20 V, melting rate 8 kg / min, cooling water pressure 0.5 MPa, and flow rate 200 L / min; the current is reduced to 30% in the arc collection stage and maintained for 3 min.

[0044] Example 7 Example 7 is based on Example 1, and the only difference between Example 7 and Example 1 is that in Example 7, in step S1, (2) the conditions of the first vacuum consumable remelting are remelting at a vacuum degree ≤1.0 Pa, melting current 15 kA, voltage 40 V, melting rate 20 kg / min, cooling water pressure 1.2 MPa, and flow rate 600 L / min; the current is reduced to 30% in the arc collection stage and maintained for 20 min.

[0045] Example 8 Example 8 is based on Example 1, the difference between Example 8 and Example 1 is only that in Example 8, the condition of the secondary vacuum self-consumption remelting in step S1 (3) is remelting under a vacuum degree of ≤1.0 Pa, a melting current of 5 kA, a voltage of 20 V, a melting rate of 10 kg / min; the control of the depth of the molten pool is 1 / 3 of the ingot diameter, the cooling water pressure is 0.5 MPa, the flow rate is 250 L / min, and the cooling rate is 5 °C / min.

[0046] Example 9 Example 9 is based on Example 1, the difference between Example 9 and Example 1 is only that in Example 9, the condition of the secondary vacuum self-consumption remelting in step S1 (3) is remelting under a vacuum degree of ≤1.0 Pa, a melting current of 35 kA, a voltage of 40 V, a melting rate of 30 kg / min; the control of the depth of the molten pool is 1 / 3 of the ingot diameter, the cooling water pressure is 1.5 MPa, the flow rate is 650 L / min, and the cooling rate is 40 °C / min.

[0047] Example 10 Example 10 is based on Example 1, the difference between Example 10 and Example 1 is only that in Example 10, the condition of the electrode induction melting in step S3 is melting at 1500 °C to continuously melt the end of the alloy rod to obtain a molten metal liquid.

[0048] Example 11 Example 11 is based on Example 1, the difference between Example 11 and Example 1 is only that in Example 11, the condition of the electrode induction melting in step S3 is melting at 1700 °C to continuously melt the end of the alloy rod to obtain a molten metal liquid.

[0049] Example 12 Example 12 is based on Example 1, the difference between Example 12 and Example 1 is only that in Example 12, the condition of the mixed gas atomization treatment in step S3 is an atomization pressure of 5 MPa, a gas flow rate of 250 m / s, and a gas-liquid ratio of 10 m 3 / kg.

[0050] Example 13 Example 13 is based on Example 1, the difference between Example 13 and Example 1 is only that in Example 13, the condition of the mixed gas atomization treatment in step S3 is an atomization pressure of 9 MPa, a gas flow rate of 600 m / s, and a gas-liquid ratio of 30 m 3 / kg.

[0051] Comparative Example 1 S1, the GH5188 master alloy ingot is smelted: (1) Vacuum induction melting: according to the chemical composition of GH5188 alloy, high-purity Co sheet, Cr sheet, Ni sheet, W strip, Fe particle, nickel-boron intermediate alloy and other raw materials are fed and melted, and after the main material is melted, La and other trace elements are fed, the target value of La is 0.060%, the introduction amount of La is 0.25%, and the refining is carried out at 1500°C for 40min, the vacuum degree is ≤10Pa; argon is filled to 0.5bar for pressure holding, and casting is carried out at 1500°C into a preheated 300°C steel mold, obtaining an alloy ingot with a diameter of 160mm and a length of 1000mm; (2) Electroslag remelting: cleaning the oxide slag on the surface of the alloy ingot, sampling the upper, middle and lower positions of the alloy ingot to detect the content of La, uniformly interval punching along the axial direction of each ingot, inserting nickel lanthanum intermediate alloy, and supplementing the La content of each ingot to 0.060%; four alloy ingots are welded end to end into a long electrode, a CaF2-CaO-Al2O3-MgO-TiO2 five-element slag system (ratio 70%:10%:15%:3%:2%) is used, the slag pool depth is 1.5 times the diameter of the electrode, under argon protective atmosphere, the melting current is 10kA, the melting voltage is 30V, the melting rate is 1.2kg / min, the cooling water flow is 400L / min, the molten pool depth is controlled to be 1 / 3 of the ingot diameter, the cooling rate is 10°C / min, and a high-homogeneity mother alloy ingot with a diameter of 320mm is obtained.

[0052] S2, after the high-homogeneity mother alloy ingot is cleaned, the diameter is changed by one-time direct rolling, heated to 1220°C, and rolled after holding for 200min, the diameter of the raw bar after rolling is 83.5mm; the raw bar is divided according to the fixed size of 950mm, and the diameter of the alloy bar is 81.5mm after surface turning, skinning and fine grinding.

[0053] S3, the alloy bar is melted by electrode induction without crucible, and the end of the alloy bar is continuously melted at 1550°C under argon protective atmosphere to obtain molten metal liquid; the molten metal liquid is treated by mixed gas atomization, the mixed gas includes Ar and CO, the purity of the mixed gas before use is ≥99.999%, the volume ratio of CO in the mixed gas is 1.5%, the gas circulation system is first circulated for 45min without material, the atomization pressure is 6MPa, the gas flow rate is 300m / s, the gas-liquid ratio is 15m 3 / kg, and the powder (A0) is obtained; the atomized gas is recycled after condensation and filtration of dust.

[0054] S4, the powder is screened, and the -100 mesh and +250 mesh powders are taken, the particle size distribution is adjusted by air flow classification, to obtain the high-homogeneity GH5188 alloy powder (A1) in the particle size range of 58-150 μm, which is applied to electron beam melting and energy deposition type additive manufacturing; the -250 mesh powder is taken, the particle size distribution is adjusted by air flow classification, to obtain the high-homogeneity GH5188 alloy powder (A2) in the particle size range of 15-53 μm, and the finished powder is applied to selective laser melting.

[0055] Comparative Example 2 S1, the GH5188 master alloy ingot is subjected to triple smelting: (1) vacuum induction melting: the raw materials such as high-purity Co sheet, Cr sheet, Ni sheet, W strip, Fe particle, nickel-boron intermediate alloy, etc. are charged and melted according to the chemical composition of the GH5188 alloy, La and other trace elements are added after the main materials are melted, the target value of La is 0.060%, the introduction amount of La is 0.25%, and the refining is carried out at 1500°C for 40 min, the vacuum degree is ≤10 Pa; argon is filled to 0.5 bar for pressure maintaining, and the alloy ingot I with a diameter of 160 mm and a length of 1000 mm is obtained by casting at 1500°C into a preheated steel mold at 300°C; (2) first vacuum consumable remelting: the oxide slag on the surface of the alloy ingot I is cleaned, the La content is detected by sampling the upper, middle and lower positions of the alloy ingot I, and the La content of each ingot is supplemented to 0.060% by inserting nickel lanthanum intermediate alloy along the axial rotation uniform interval punching, four alloy ingots are welded into a long electrode I according to the head-to-tail welding, and the first vacuum consumable remelting is carried out under a vacuum degree of ≤1.0 Pa, a melting current of 6 kA, a voltage of 25 V, a melting rate of 10 kg / min, a cooling water pressure of 0.7 MPa, and a flow of 300 L / min; the current is reduced to 30% during the arc recovery stage and maintained for 5 min, and the alloy ingot II with a diameter of 230 mm is obtained; (3) second vacuum consumable remelting: the oxide slag on the surface of the alloy ingot II is cleaned, the riser is cut off, two alloy ingots II are welded into a long electrode II according to the head-to-tail welding, and the second vacuum consumable remelting is carried out under a vacuum degree of ≤1.0 Pa, a melting current of 10 kA, a voltage of 25 V, and a melting rate of 15 kg / min; the depth of the molten pool is controlled to be 1 / 3 of the diameter of the ingot, the cooling water pressure is 0.8 MPa, the flow is 350 L / min, the cooling rate is 10°C / min, and the high-homogeneity master alloy ingot with a diameter of 320 mm is obtained.

[0056] S2, after the surface slagging of the high homogenization master alloy ingot, the diameter is changed by one-time direct rolling, heated to 1220℃, and kept for 200min before rolling. The diameter of the raw bar after rolling is 83.5mm; the raw bar is cut according to the fixed size of 950mm, and the skin is scraped by surface turning and the alloy bar with a diameter of 81.5mm is obtained by fine grinding.

[0057] S3, the alloy bar is vacuum gas atomized with a crucible, is loaded into an alumina ceramic crucible, is vacuumized to ≤10 -2 Pa in a vacuum induction furnace, is filled with argon to 0.05bar for pressure maintaining, is heated to 1550℃ at a rate of 10℃ / min, is kept for 30min for refining, and the vacuum degree is maintained to ≤1Pa during the refining process to obtain molten metal liquid; the molten metal liquid is subjected to mixed gas atomization treatment, the mixed gas includes Ar and CO, the purity of the mixed gas before use is ≥99.999%, the volume ratio of CO in the mixed gas is 1.5%, the gas circulation system is first used for 45min of empty circulation without material, the atomization pressure is 6MPa, the gas flow rate is 300m / s, and the gas-liquid ratio is 15m 3 / kg to obtain powder (A0); the atomized gas is recycled after being subjected to impurity removal by condensation and dust filtration.

[0058] S4, the powder is subjected to screening treatment, is screened through 100mesh and 250mesh, the -100mesh and +250mesh powders are taken, the particle size distribution is adjusted by airflow classification to obtain high homogenization GH5188 alloy powder (A1) in the particle size range of 58-150μm, which is applied to electron beam melting and energy deposition type additive manufacturing; the -250mesh powder is taken, the particle size distribution is adjusted by airflow classification to obtain high homogenization GH5188 alloy powder (A2) in the particle size range of 15-53μm, and the finished powder is applied to selective laser melting.

[0059] Performance detection test The high homogenization GH5188 alloy powders A0, A1 and A2 prepared in the examples and the comparative examples are subjected to oxygen content test and La content test, the oxygen content is tested by an oxygen-nitrogen instrument, the La content is tested by an inductively coupled plasma mass spectrometer, and the results are recorded in Table 1.

[0060] Table 1: Detection results of oxygen content and La content As shown in Table 1, the O content of A0 in Examples 1-3 is less than 76ppm, the La content is close to the target value, the O content of A1 is less than 47ppm, the La content is close to the target value, the O content of A2 is less than 97ppm, and the La content is close to the target value, so it can be seen that the GH5188 alloy powder prepared in the present application has good composition uniformity and stability.

[0061] As shown in Table 1, the difference between Example 4-13 and Example 1 is only that the ratio of Example 4-13 is out of the defined range, and the performance is decreased; this is because under the low process parameter condition in Example 4, 6, 8, 10, 12, the oxidation can be reduced, but the process time is prolonged, and the diffusion of La element is not uniform, and the content of the required additional lanthanum element is increased; under the high process parameter condition in Example 5, 7, 9, 11, 13, the oxygen content in the powder is increased, and the volatilization of La is intensified, so that the uniformity and stability of the alloy powder are decreased.

[0062] As shown in Table 1, the difference between Comparative Example 1 and Example 3 is only that the vacuum consumable remelting in the triple smelting in Comparative Example 1 is replaced by electroslag remelting, and the performance of Comparative Example 1 is obviously decreased compared with Example 3; this is because the vacuum consumable remelting can reduce the oxygen content, and the electroslag remelting is more likely to cause the contact oxygen increase problem, and the oxidation slag can cause a large loss of La, so that the performance is decreased.

[0063] As shown in Table 1, the difference between Comparative Example 2 and Example 3 is only that the non-crucible electrode induction melting in Comparative Example 2 is replaced by the crucible atomization, and the performance of Comparative Example 2 is obviously decreased compared with Example 3; the crucible material, the reaction of dross with La and high temperature can intensify the loss of La, so that the performance is obviously decreased.

[0064] The specific embodiments are only an explanation of the present application, and are not a limitation of the present application, and through the above description, the related workers can make various changes and modifications without departing from the technical idea of the present application. The technical scope of the present application is not limited to the content in the specification, and the technical scope must be determined according to the scope of claims.

Claims

1. A method for preparing a high homogeneity GH5188 alloy powder suitable for additive manufacturing, characterized in that: The method comprises the following steps: S1, triple smelting is performed on the GH5188 master alloy ingot to obtain a high-homogeneity master alloy ingot; the triple smelting comprises vacuum induction smelting, first vacuum consumable remelting and second vacuum consumable remelting; S2, the high-homogeneity master alloy ingot is rolled and processed to obtain an alloy rod; S3, the alloy rod is subjected to electrode induction smelting without a crucible and mixed gas atomization treatment, the mixed gas comprising Ar and CO, to obtain a powder; S4, the powder is subjected to screening treatment to obtain a high-homogeneity GH5188 alloy powder with a target particle size.

2. A method for preparing a high homogeneity GH5188 alloy powder suitable for additive manufacturing according to claim 1, characterized in that: The triple smelting in the step S1 comprises the following steps: (1) vacuum induction smelting: Co, Cr, Ni, W, Fe, La and other raw materials are added according to the composition ratio of the GH5188 alloy, the La addition amount is 1-10 times the target value, and after smelting, the alloy round ingot I with a diameter of 100-250 mm and a length of 650-1500 mm is cast in a mold; (2) first vacuum consumable remelting: the oxide slag on the surface of the alloy round ingot I is cleaned, and the content of La is determined through composition detection; after the content of La is supplemented to the target content, 2-5 alloy round ingots are welded end to end to form a long electrode I for first vacuum consumable remelting to obtain the alloy round ingot II; (3) second vacuum consumable remelting: the oxide slag and riser on the surface of the alloy round ingot II are cleaned, and the alloy round ingot II is welded end to end to form a long electrode II for second vacuum consumable remelting to obtain the high-homogeneity master alloy ingot.

3. A method for preparing a high homogeneity GH5188 alloy powder suitable for additive manufacturing according to claim 2, characterized in that: The conditions for the vacuum induction smelting in the step (1) are refining at 1500-1600 ℃ for 20-40 min, vacuum degree ≤10 Pa, argon filling to 0.5-0.6 bar for pressure maintaining, and casting into a preheated mold at 1500-1550 ℃.

4. The method for preparing a high homogeneity GH5188 alloy powder suitable for additive manufacturing according to claim 3, characterized in that: The conditions for the first vacuum consumable remelting in the step (2) are remelting at a vacuum degree ≤1.0 Pa, melting current 6-12 kA, voltage 25-35 V, melting rate 10-15 kg / min, cooling water pressure 0.7-1.0 MPa, and flow rate 300-500 L / min; the current is reduced to 30% in stages during the arc recovery stage and maintained for 5-15 min.

5. A method for preparing a high homogeneity GH5188 alloy powder suitable for additive manufacturing according to claim 4, characterized in that: The conditions for the second vacuum consumable remelting in the step (3) are remelting at a vacuum degree ≤1.0 Pa, melting current 10-30 kA, voltage 25-35 V, and melting rate 15-25 kg / min; the depth of the molten pool is controlled to be 1 / 3 of the diameter of the ingot, the cooling water pressure is 0.8-1.2 MPa, the flow rate is 350-550 L / min, and the cooling rate is 10-30 ℃ / min.

6. A method for preparing a high homogeneity GH5188 alloy powder suitable for additive manufacturing according to claim 1, characterized in that: In the step S2, the high-homogeneity master alloy ingot is directly rolled to change the diameter to obtain a rough rod, and the diameter of the rough rod has a machining allowance of 0.5-5 mm; the rough rods are segmented according to a fixed size of 680-1080 mm, and processed into alloy rods with a diameter of 80-150 mm.

7. The method for preparing a high homogeneity GH5188 alloy powder suitable for additive manufacturing according to claim 1, characterized in that: The electrode induction smelting conditions in the step S3 are smelting at 1550-1650 ℃ in a protective atmosphere to continuously melt the end of the alloy rod to obtain a molten metal liquid.

8. A method for preparing a high homogeneity GH5188 alloy powder suitable for additive manufacturing according to claim 7, characterized in that: The condition of the mixed gas atomization treatment in the step S3 is that the molten metal liquid is atomized by using mixed gas, and the volume ratio of CO in the mixed gas is 0.1% to 10%.

9. A method for preparing a high homogeneity GH5188 alloy powder suitable for additive manufacturing according to claim 8, characterized in that: The conditions of the mixed gas atomization treatment in step S3 are atomization pressure of 6-8 MPa, gas flow rate of 300-500 m / s, and gas-liquid ratio of 15-25 m 3 / kg.

10. A method for preparing a high homogeneity GH5188 alloy powder suitable for additive manufacturing according to claim 9, characterized in that: The purity of the mixed gas before use is greater than or equal to 99.999%, and the mixed gas is uniformly mixed for 40 to 50 min without material empty cycle, and the atomized gas is recycled after being condensed and impurity-removed and filtered dust.

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