A t-shaped slag stopping device and a method for suppressing viga powder inclusions

Abstract

This invention belongs to the field of alloy smelting technology, specifically relating to a T-shaped slag-blocking device and a method for suppressing VIGA powder inclusions. The T-shaped slag-blocking device consists of a T-shaped slag-blocking plate and a smelting crucible with grooved inner walls. The T-shaped slag-blocking plate comprises Al2O3, ZrO2, Cr2O3 materials, and a CaZrO3 coating. Based on the total mass content of the materials, Al2O3 accounts for 85-90%, ZrO2 for 5-10%, and Cr2O3 for 1-5%. The CaZrO3 coating has a thickness of 0.2-0.5 mm and a porosity of 5-8%. This slag-blocking device can be firmly installed, effectively handles floating slag, and solves the problem of disturbance to the molten steel flow field caused by the introduction of the slag-blocking plate.

Description

Technical Field

[0001] This invention specifically relates to a T-shaped slag-blocking device and a method for suppressing inclusions in VIGA powder, belonging to the field of alloy smelting technology. Background Technology

[0002] VIGA is a powder-making device that uses induction melting of metal raw materials into a liquid state under vacuum or inert gas protection, and then atomizes the molten metal into metal powder using inert gas during casting. This equipment effectively prevents metal oxidation during melting and atomization, and achieves rapid solidification through high-pressure gas impact, resulting in powders with uniform structure and high purity. VIGA-produced high-temperature alloy powders have a fine and uniform structure with lower elemental segregation than traditional castings. Its high sphericity and good flowability are crucial for the uniformity of powder spreading and the density of finished parts in 3D printing, making it one of the mainstream raw materials for metal 3D printing. Currently, VIGA powder is not only used in aerospace parts manufacturing but is also gradually being applied in high-end molds, medical implants, and other fields, providing a fundamental material for modern cutting-edge manufacturing.

[0003] During the tilting pouring process, VIGA inevitably brings up slag from the surface of the molten steel. Large inclusions can clog the VIGA nozzles, causing atomization interruption and increasing production costs. Slag inclusions in the molten steel also degrade the mechanical properties of powder-printed parts, affecting product quality. Therefore, the oxide slag generated during the smelting process needs to be treated. VIGA furnaces operate in a vacuum or inert gas environment; if slag is skimmed off by opening the furnace lid, similar to non-vacuum smelting, it will result in high oxygen and nitrogen levels in the powder. Currently, VIGA's conventional method for treating slag is to place a ceramic filter in the tundish, but the filter's effectiveness is limited, especially with large amounts of slag. Existing furnace baffles often suffer from problems such as easily inductive metal fasteners, complex shapes leading to high costs, insecure installation, and disturbance of the molten steel flow field, ultimately affecting the performance of the alloy-melted steel.

[0004] In summary, the existing technology has obvious shortcomings. Therefore, it is very important to provide a furnace slag-blocking device in the VIGA process that can be firmly installed, effectively handle floating slag, suppress powder inclusions in conjunction with the VIGA process, and solve problems such as disturbance to the molten steel flow field. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a T-shaped slag-blocking device and a method for suppressing VIGA powder inclusions. This slag-blocking device can be firmly installed, effectively handles floating slag, and solves problems such as the disturbance of the molten steel flow field caused by the introduction of slag-blocking plates.

[0006] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: a T-shaped slag-blocking device, the T-shaped slag-blocking device is composed of a T-shaped slag-blocking plate and a smelting crucible with grooves on the inner wall; the T-shaped slag-blocking plate includes Al2O3, ZrO2, Cr2O3 materials and CaZrO3 coating; according to the total mass content of the materials, Al2O3 is 85~90%, ZrO2 is 5~10% and Cr2O3 is 1~5%.

[0007] Furthermore, the thickness of the CaZrO3 coating is 0.2~0.5mm; the porosity of the coating is 5~8%.

[0008] Furthermore, the T-shaped slag baffle has a continuous upper and lower end. The thickness of the T-shaped slag baffle is 1.5~3.5cm; the height of the lower end is 14~30cm and the width is 22~29cm; the height of the upper end of the T-shaped slag baffle is 4~8cm and the width is 26~33cm.

[0009] Furthermore, the smelting crucible is cylindrical, and the crucible spout is made of prefabricated flow channels and refractory clay; two grooves for installing slag baffles are opened on the inner wall of the crucible near the spout; the grooves form an angle of 40° to 75° with the horizontal plane.

[0010] Furthermore, the inner diameter of the smelting crucible is 32-45 cm, the wall thickness is 3-4 cm, and the height is 75-100 cm.

[0011] Furthermore, an expansion joint is reserved at the connection between the slag baffle plate and the crucible lining, and filled with high-purity alumina fiber felt.

[0012] The present invention also discloses a method for suppressing inclusions in VIGA powder, which requires the use of the T-type slag-blocking device provided by the present invention.

[0013] Furthermore, the method for suppressing inclusions in VIGA powder includes the following steps: S1. Remove impurities from the surface of the T-shaped slag baffle and the smelting crucible; S2. Assemble the T-shaped slag-blocking device and install it inside the VIGA intermediate frequency coil for baking; S3. Load the raw materials into the furnace in a tight-to-loose manner from bottom to top. Do not load materials into the gap between the slag baffle and the crucible wall. Place 2-3 large pure nickel plates or master alloy ingots vertically close to the slag baffle. After closing the furnace lid, S4 and VIGA will draw a vacuum, and then start the medium frequency power supply to begin melting until the raw materials are clear. S5. After cleaning, shake the crucible toward the spout side to bring the molten steel surface close to the slag baffle plate, and refine the crucible in an inclined state. The refining temperature is 1530~1590℃, and the total refining time is 50~80min. S6. After refining, return the crucible to the correct position, quickly heat it to the casting temperature, and then turn on the atomization chamber fan and atomizing gas to start the furnace shaking and casting process.

[0014] Furthermore, in step S2, the baking temperature is 300~600℃, and the baking time is 5~8h; Furthermore, in step S4, the melting chamber is evacuated to below 5 Pa. In the initial stage of melting, the power supply is controlled at 20%~30% of the rated power and maintained for 15~30 minutes, and then the power is increased to 60~80%.

[0015] Furthermore, in step S5, the refining process is divided into three stages, which are carried out continuously while the crucible is tilted. First stage: Adjust the power of the medium frequency power supply to 70%~80% of the rated power, evacuate the vacuum degree of the melting chamber to below 3Pa, and stir clockwise at a low frequency of 3~5Hz for 10~20 minutes; Second stage: Reduce the power of the medium frequency power supply to 40%~50% of the rated power, and stir counterclockwise at 100~150Hz for 15~30 minutes; Third stage: Increase the power of the medium frequency power supply to 70%~80% of the rated power, and stir counterclockwise for 12~25 minutes using medium frequency 90~150Hz.

[0016] The beneficial effects of this invention are: (1) The method for suppressing VIGA powder inclusions provided by the present invention significantly reduces powder inclusions. Through the combined effect of physical interception and adsorption by the T-shaped slag baffle and the VIGA smelting process, the content of non-metallic inclusions (oxides, nitrides, etc.) in VIGA atomized powder is greatly reduced, thereby improving powder purity.

[0017] (2) The T-shaped slag-blocking device provided by the present invention has a slag-blocking plate that can withstand rapid heating and cooling of molten steel and long-term high-temperature refining through material compounding and coating design, making it less prone to cracking and peeling, and extending its service life.

[0018] (3) The method for suppressing VIGA powder inclusions provided by this invention optimizes the flow of molten steel and the efficiency of inclusion removal. The T-shaped structure and inclined installation angle (40°~75°) of the slag baffle plate form a stable retention area when the crucible is shaken, which is conducive to the floating and adsorption of fine inclusions on the surface of the slag baffle plate. When charging, the nickel plate / master alloy ingot is vertically enlarged close to the slag baffle plate to avoid the furnace charge collapsing and directly damaging the slag baffle plate; expansion joints are reserved and filled with alumina fiber felt to prevent damage from thermal expansion stress. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a T-shaped slag baffle plate. Figure 2 This is a side view of the melting crucible; Figure 3 Side view of the T-shaped slag baffle plate after it has been installed in the smelting crucible; Figure 4 Top view of the T-shaped slag baffle plate after it has been installed in the smelting crucible; Figure 5 The first to fourth fields of view for SEM analysis of the powder obtained in Example 1; Figure 6 The fifth to eighth fields of view of the powder obtained in Example 1 were obtained by SEM analysis. Figure 7 The 9th to 12th fields of view for SEM analysis of the powder obtained in Example 1; Figure 8 Fields 13 to 16 of SEM images of the powder obtained in Example 1; Figure 9 The 17th to 20th fields of view are SEM images of the powder obtained in Example 1.

[0020] Reference numerals: 1. T-shaped slag baffle; 2. Lower end; 3. Upper end; 4. Melting crucible; 5. Pour nozzle; 6. Groove. Detailed Implementation

[0021] The specific embodiments of the present invention will be described in detail below. The present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used is for describing particular embodiments only and is not intended to limit the invention.

[0023] This invention provides a T-shaped slag-blocking device, which consists of a T-shaped slag-blocking plate and a smelting crucible with grooved inner walls. The T-shaped slag-blocking plate comprises Al2O3, ZrO2, Cr2O3 materials and a CaZrO3 coating. Based on the total mass content of the materials, Al2O3 accounts for 85-90%, ZrO2 for 5-10%, and Cr2O3 for 1-5%. Preferably, the mass ratio of ZrO2 to Cr2O3 is (3-5):1.

[0024] It should be noted that the thickness of the CaZrO3 coating is 0.2~0.5mm; the porosity of the coating is 5~8%.

[0025] The T-shaped slag baffle of the present invention achieves efficient adsorption of inclusions in molten steel and a significant improvement in the thermal shock resistance and erosion resistance of the slag baffle itself through the synergistic cooperation of the Al2O3, ZrO2, and Cr2O3 composite matrix and the surface CaZrO3 coating. This is mainly due to the solid solution strengthening and toughening coupling between the matrix components and the interface matching and functional relay between the coating and the matrix.

[0026] At the base layer, Al2O3 serves as the matrix framework, providing high refractoriness and high-temperature strength; ZrO2 utilizes its phase transformation toughening mechanism to absorb thermal stress, significantly improving the thermal shock resistance of the slag baffle plate, while its low thermal conductivity ensures a more uniform temperature distribution on the plate surface; the CaZrO3 coating on the matrix surface possesses a high melting point, chemical inertness, and a thermal expansion coefficient similar to the matrix, ensuring that the coating is not easily peeled off under rapid heating and cooling conditions. These three components form a dense, well-balanced composite matrix. Al2O3 and Cr2O3 exhibit extremely high affinity in their crystal structures, due to Al... 3+ and Cr 3+ With highly similar ionic radii and charges, the two can form a continuous (Al,Cr)₂O₃ solid solution. This solid solution strengthening mechanism significantly improves the mechanical strength and wear resistance of the matrix, while chemically enhancing the material's resistance to corrosion. When the ZrO₂ content is too high, the porosity of the material increases, and the mechanical properties decrease. Therefore, ZrO₂ must be controlled within the range of 5% to 10% as described in this invention. The introduction of ZrO₂ serves the dual function of toughening and regulating thermal shock stability. The unique martensitic phase transformation characteristics of ZrO₂ are the core of its toughening mechanism. Under high-temperature operating conditions, the metastable tetragonal phase ZrO₂ (t-ZrO₂) is uniformly dispersed in the matrix. When the material is subjected to thermal stress impact, t-ZrO₂ undergoes a martensitic phase transformation under the stress field, transforming into a larger monoclinic phase (m-ZrO₂), forming a compressive stress field at the crack tip, effectively passivating the crack and dissipating destructive energy, thereby significantly improving the material's thermal shock resistance. Meanwhile, the spontaneous phase transformation of ZrO2 grains during cooling induces a microcrack network in the matrix. These microcracks disperse the stress concentration at the tip of the main crack through the bifurcation effect, further absorbing fracture energy and forming a microcrack toughening mechanism. The best toughening effect is achieved when the ZrO2 content is 5%~10%. When the ZrO2 content is less than 5%, the phase transformation toughening effect is insufficient, the thermal shock resistance decreases, and the slag baffle is prone to cracking and failure under rapid cooling and heating conditions during the refining process. When the ZrO2 content exceeds 10%, the excessive microcracks generated by the phase transformation expand excessively, which reduces the matrix density and mechanical strength.

[0027] The CaZrO3 coating forms a functional relay with the substrate. CaZrO3 has a high melting point of approximately 2340℃ and excellent chemical inertness. Its coefficient of thermal expansion is between that of Al2O3 and ZrO2, similar to that of the composite substrate, ensuring that the coating is not prone to peeling due to thermal stress mismatch during rapid heating and cooling cycles. Controlling the coating thickness to 0.2~0.5mm is key to balancing wear resistance and peeling resistance. Coatings that are too thin are easily worn away and fail under the scouring of molten steel, while coatings that are too thick will peel off due to accumulated internal stress during thermal cycling. A porosity of 5~8% effectively prevents molten metal from penetrating into the gaps and microcracks within the coating, preventing chemical corrosion and physical erosion, thus ensuring the integrity of the coating and allowing the T-shaped slag baffle to be reused. A porosity exceeding 8% results in a decrease in strength, and molten steel may penetrate.

[0028] In some embodiments, a schematic diagram of the T-shaped slag baffle is shown below. Figure 1 As shown, the thickness of the T-shaped slag baffle is 1.5~3.5cm; the T-shaped slag baffle is divided into two parts, the lower end 2 is 14~30cm high and 22~29cm wide, and is below the crucible rim; the upper end 3 of the T-shaped slag baffle is 4~8cm high and 26~33cm wide, and is above the crucible rim.

[0029] In some embodiments, the melting crucible is cylindrical, and the side view of the melting crucible 4 is shown below. Figure 2 As shown, the crucible spout 5 is made of prefabricated flow channels and refractory clay. Two grooves 6 for installing slag-blocking plates are formed on the inner wall of the crucible near the spout. These grooves form an angle of 40° to 75° with the horizontal plane. When the length of the slag-blocking plates is the same, if the angle is less than 40°, the slag-blocking plate is too flat, the retention zone effect is weak, and inclusions easily flow out with the molten steel. If the angle is greater than 75°, the slag-blocking plate is nearly vertical, increasing the scouring force of the molten steel on the plate surface, accelerating coating wear, and simultaneously affecting the flow of the molten steel during casting.

[0030] Specifically, the inner diameter of the smelting crucible is 32-45cm, the wall thickness is 3-4cm, and the height is 75-100cm.

[0031] It should be noted that the installation of the slag baffle plate is completed by inserting it into the grooves on both sides. After the slag baffle plate is inserted into the crucible grooves, its protruding parts on both sides rest precisely on the edge of the crucible. The side and top views of the T-shaped slag baffle plate after installation in the smelting crucible are shown below. Figure 3 and 4As shown. An expansion joint is reserved at the connection between the slag-blocking plate and the crucible lining, and filled with high-purity alumina fiber felt to absorb thermal expansion and prevent hard compression. This design effectively reduces the immersion depth and disturbance during steel pouring while achieving the slag-blocking effect. The portion of the slag-blocking plate above the crucible rim should be as long as possible without obstructing the line of sight of the pouring personnel, preventing slag from overflowing above the plate during tilting of the furnace. The portion of the slag-blocking plate below the crucible rim should be as short as possible while ensuring the slag-blocking effect, avoiding affecting the crucible's charge capacity. The two grooves on the inner wall of the smelting crucible should be as close as possible to the pouring nozzle, which reduces the size of the slag-blocking plate without affecting the charge capacity.

[0032] The present invention also provides a method for suppressing inclusions in VIGA powder, which requires the use of the T-type slag-blocking device provided by the present invention.

[0033] Specifically, the method for suppressing inclusions in VIGA powder includes the following steps: S1. Remove impurities from the surface of the T-shaped slag baffle and the smelting crucible; S2. Assemble the T-shaped slag-blocking device and install it inside the VIGA intermediate frequency coil for baking; S3. Load the raw materials into the furnace in a tight-to-loose manner from bottom to top. Do not load materials into the gap between the slag baffle and the crucible wall. Place 2-3 large pure nickel plates or master alloy ingots vertically close to the slag baffle. After closing the furnace lid, S4 and VIGA will draw a vacuum, and then start the medium frequency power supply to begin melting until the raw materials are clear. S5. After cleaning, shake the crucible towards the spout side to bring the molten steel surface close to the slag baffle. With the crucible tilted, keep the lower edge of the slag baffle at a position 2-6 cm from the molten steel surface for refining. The refining temperature is 1530-1590℃ and the total refining time is 50-80 min. S6. After refining, return the crucible to the correct position, quickly heat it to the casting temperature, and then turn on the atomization chamber fan and atomizing gas to start the furnace shaking and casting process.

[0034] In some embodiments, the operation in step S1 is to grind and blow away impurities on the surface of the T-shaped slag baffle and the melting crucible to prevent impurities from peeling off and introducing inclusions during use.

[0035] Specifically, in step S2, the baking temperature is 300~600℃, and the baking time is 5~8 hours; ensure that all moisture is removed to prevent moisture from evaporating and causing cracking during use. After baking, reduce the crucible temperature to about 150℃.

[0036] It should be noted that placing 2-3 large pure nickel plates or master alloy ingots vertically close to the slag baffle plate is to prevent the slag baffle plate from being damaged when the furnace charge collapses during the initial melting stage.

[0037] In some embodiments, in step S3, the pure nickel plate has a length and width of 15-20 cm and a thickness of 2-3 cm. The master alloy ingot has a length and width of 15-20 cm and a thickness of 5-8 cm.

[0038] Specifically, in step S4, the melting chamber is evacuated to below 5 Pa. In the initial stage of melting, the power supply is controlled at 20%~30% of the rated power and maintained for 15~30 minutes. Then, the power is increased to 60~80% at a rate of (5~10) Kw / min.

[0039] After the steel has molten and cleared, shake the crucible towards the pouring nozzle to bring the molten steel surface as close as possible to the slag baffle. The main purpose of this operation is to heat the slag baffle to prevent it from being damaged by sudden heat when it comes into contact with the high-temperature molten steel during pouring.

[0040] Specifically, in step S5, refining is divided into three stages, which are carried out continuously while the crucible is tilted. First stage: Adjust the power of the medium frequency power supply to 70%~80% of the rated power, evacuate the vacuum degree of the melting chamber to below 3Pa, and stir clockwise at a low frequency of 3~5Hz for 10~20 minutes; Second stage: Reduce the power of the medium frequency power supply to 40%~50% of the rated power, and stir counterclockwise at 100~150Hz for 15~30 minutes; Third stage: Increase the power of the medium frequency power supply to 70%~80% of the rated power, and stir counterclockwise for 12~25 minutes using medium frequency 90~150Hz.

[0041] Understandably, the invention of the refining process optimizes three physicochemical processes—gas removal, inclusion adsorption, and collision aggregation—by controlling power, vacuum level, and stirring direction in stages. The underlying mechanism is as follows: In the first stage, 70%~80% of the rated power is used and the vacuum is reduced to below 3 Pa. According to Sivez's law, the equilibrium solubility of diatomic gases (H2, N2) in molten steel is proportional to the square root of the gas phase partial pressure. Evacuating the melting chamber to an ultra-low vacuum can greatly reduce the gas phase partial pressure, providing a strong thermodynamic driving force for degassing. Low-frequency clockwise stirring is used (low-frequency current has a large penetration depth, which can achieve overall molten pool agitation rather than surface skin effect), continuously bringing dissolved gases in the deep molten steel to the free surface to escape, accelerating the mass transfer process. The second stage reduces the power to 40%~50% and switches to counterclockwise stirring. The core of this stage is to promote inclusion adsorption by utilizing low-speed flow and the stagnation zone effect: the lower power weakens the electromagnetic stirring intensity, and the molten steel changes from turbulent flow to slow flow. At this time, a stagnation zone is formed on the back side of the slag baffle, and the residence time of inclusions in this area is significantly extended. In addition, the reduced flow velocity of the molten steel thickens the boundary layer, and the collision probability and adhesion force between inclusions and the surface of the slag baffle both increase. The role of counterclockwise stirring is to change the direction of the Lorentz force, which reverses the flow pattern of the molten steel. The original stagnation zone is transformed into a micro-turbulent zone, and a new stagnation zone appears on the other side. This dynamic switching makes the two sides of the slag baffle alternate as inclusion trapping zones, preventing inclusions that have accumulated in a single stagnation zone from being rolled back into the mainstream. At the same time, it disrupts the stable flow lines and increases the randomness of the collision between inclusions and the wall. The third stage, with power at 70%–80% and clockwise stirring, utilizes the shear aggregation and enhanced flotation caused by sudden changes in flow velocity. The molten steel flow velocity undergoes a dramatic change, generating a transient high shear rate. According to turbulent collision theory, the collision frequency of inclusions is proportional to the square root of the turbulent dissipation rate. The strong shear flow field intensifies the relative motion of small inclusions, driving them to collide and merge into larger clusters. High temperature reduces viscosity, further accelerating the flotation rate of large particles. The macroscopic circulation generated by high-speed clockwise stirring continuously brings bottom inclusions to the surface. These three stages sequentially complete degassing, adsorption, and aggregation flotation, overcoming the limitations of a single stirring mode in simultaneously addressing multiple purification mechanisms and achieving optimal performance of each mechanism, ultimately maximizing the purity of the molten steel.

[0042] It should be noted that after refining, the crucible is returned to its upright position, and the power of the medium-frequency power supply is increased to rapidly raise the temperature. After the molten steel reaches the pouring temperature, the atomization chamber fan and atomizing gas are turned on to begin the furnace shaking process for pouring. The shaking motion should be gentle to avoid impacting the slag baffle plate and to prevent the molten steel from overflowing over the baffle plate. In the initial stage of pouring the steel with the crucible tilted, the tilting angle should be small and slow, allowing the molten steel to just overflow the bottom of the baffle plate and enter the pouring spout at a very low speed. The purpose is to prevent the molten steel from suddenly gushing out and entraining the slag in front of the baffle plate. During the middle stage of pouring, a stable and continuous pouring speed is maintained. At this time, the guiding effect of the baffle plate is most obvious, which can smoothly guide the clean molten steel below to the pouring spout. In the later stage of pouring, when the molten steel level drops to near the bottom edge of the baffle plate, there is a risk that the slag will re-enter the steel flow. At this time, the tilting speed should be appropriately increased to allow the remaining molten steel to rush out quickly, using inertia to briefly suppress the slag and complete the pouring. Open the furnace lid at least 2 hours after steel pouring to prevent powder oxidation. Clean up any slag remaining on the furnace walls and slag baffle surfaces.

[0043] In some embodiments of the present invention, the vacuum induction melting gasification atomization equipment used is from AVIC MAT Additive Manufacturing Technology Co., Ltd., and the model is VIGA500.

[0044] In some embodiments, the alloy smelting can be selected as follows: (1) The alloy grade for smelting is GH4169, and the composition is: 19.5%Cr, 5.1%Nb, 0.6%Al, 0.95%Ti, 52%Ni, 3%Mo, 0.03%C, 18.8%Fe, and the furnace charge is 300kg.

[0045] (2) The alloy grade for smelting is GH3625, with the following composition: 21.5%Cr, 3.8%Nb, 0.3%Al, 0.3%Ti, 62.3%Ni, 9%Mo, 0.06%C, and 2%Fe. The furnace charge is 300kg.

[0046] To better illustrate the embodiments of the present invention, the present invention will be further described in detail below through specific examples.

[0047] Example 1

[0048] A method for suppressing inclusions in VIGA powder is provided. The alloy used for smelting is GH4169, with the following composition: 19.5% Cr, 5.1% Nb, 0.6% Al, 0.95% Ti, 52% Ni, 3% Mo, 0.03% C, and 18.8% Fe. The furnace charge is 300 kg. This embodiment specifically includes the following steps: (1) Preparation of slag baffles: The T-shaped slag baffles are made of Al2O3 (90%), ZrO2 (8%) and Cr2O3 (2%) by weight of materials. The surface is coated with a CaZrO3 coating with a porosity of 6% and a thickness of 0.3 mm. The thickness of the T-shaped slag baffles is 3 cm; the height of the lower end is 17 cm and the width is 29 cm; the height of the upper end of the T-shaped slag baffles is 5 cm and the width is 33 cm.

[0049] (2) Preparation of the smelting crucible: The inner diameter of the smelting crucible is 38cm, the wall thickness is 3.5cm, and the height is 80cm. The grooving angle forms a 75° angle with the horizontal plane. The grooving width is the same as the thickness of the slag baffle plate, which is 3cm, and the grooving length is the same as the height of the lower end of the slag baffle plate.

[0050] (3) The method for suppressing inclusions in VIGA powder includes the following steps: S1. Grind and clean the T-shaped slag baffle and the surface of the smelting crucible to remove impurities; S2. Assemble the T-shaped slag-blocking device by filling the crucible groove with 3mm thick high-purity alumina fiber felt. After the slag-blocking plate is inserted into the crucible groove, its protruding parts on both sides should rest on the crucible rim. Then install it inside the VIGA intermediate frequency coil and bake it at 550℃ for 7 hours. S3. Reduce the crucible temperature to about 150℃, and load the raw materials into the furnace in a way that is tight at the bottom and loose at the top. Do not load materials into the gap between the slag baffle and the crucible wall. Place two large pure nickel plates vertically close to the slag baffle. After closing the furnace lid, S4 and VIGA are vacuumed. The melting chamber is vacuumed to below 5Pa. Then, the medium frequency power supply is started to begin melting. The medium frequency power supply power is 60Kw to preheat the raw material for 20 minutes. Then, the power is increased to 250Kw at 6Kw / min until the raw material is clear. S5. After cleaning, shake the crucible towards the spout side to bring the molten steel surface close to the slag baffle. With the crucible tilted, control the lower edge of the slag baffle at a position 2-6cm away from the molten steel surface for refining. First stage: Adjust the medium frequency power supply to the rated power of 230Kw, evacuate the vacuum degree of the melting chamber to below 3Pa, and use low frequency 3-5Hz clockwise stirring for 20min. Second stage: Reduce the power of the medium frequency power supply to 120Kw, and stir counterclockwise at 100Hz medium frequency for 20 minutes; Third stage: Increase the power of the medium frequency power supply to 240Kw, and stir clockwise at 100Hz for 20 minutes.

[0051] S6. After refining, return the crucible to the correct position, increase the medium frequency power supply to 270Kw to quickly heat up to the steel casting temperature, turn on the atomization chamber fan and atomizing gas to start shaking the furnace for steel casting, and collect the powder two hours after steel casting is completed.

[0052] The powder obtained in Example 1 was subjected to SEM analysis, and 20 fields of view were captured. Figure 5 These are the first four field-of-view images taken. Figure 6 These are the 5th to 8th field-of-view images taken. Figure 7 These are the 9th to 12th field-of-view images taken. Figure 8 These are the 13th to 16th field-of-view images taken. Figure 9 These are the 17th to 20th field-of-view images taken.

[0053] Example 2

[0054] This embodiment provides a method for suppressing inclusions in VIGA powder. The alloy grade is GH3625, and the composition is: 21.5%Cr, 3.8%Nb, 0.3%Al, 0.3%Ti, 62.3%Ni, 9%Mo, 0.06%C, 2%Fe, and the furnace charge is 300kg.

[0055] The same method as in Example 1 was used to prepare the T-shaped slag baffle and the smelting crucible.

[0056] The method for suppressing inclusions in VIGA powder includes the following steps: S1. Grind and clean the T-shaped slag baffle and the surface of the smelting crucible to remove impurities; S2. Assemble the T-shaped slag-blocking device by filling the crucible groove with 3mm thick high-purity alumina fiber felt. After the slag-blocking plate is inserted into the crucible groove, its protruding parts on both sides should rest on the crucible rim. Then install it inside the VIGA intermediate frequency coil and bake it at 500℃ for 6 hours. S3. Reduce the crucible temperature to about 150℃, load the raw materials into the furnace in a tight bottom and loose top manner, and do not load materials into the gap between the slag baffle and the crucible wall. Place three large pure nickel plates vertically close to the slag baffle. After closing the furnace lid, S4 and VIGA are vacuumed. The melting chamber is vacuumed to below 5Pa. Then, the medium frequency power supply is started to begin melting. The medium frequency power supply is 55Kw to preheat the raw material for 20 minutes. Then, the power is increased to 250Kw at 6Kw / min until the raw material is clear. S5. After cleaning, shake the crucible towards the spout side to bring the molten steel surface close to the slag baffle. With the crucible tilted, control the lower edge of the slag baffle at a position 2-6cm away from the molten steel surface for refining. First stage: Adjust the medium frequency power supply to the rated power of 210Kw, evacuate the vacuum degree of the melting chamber to below 3Pa, and use low frequency 3-5Hz clockwise stirring for 20min. Second stage: Reduce the power of the medium frequency power supply to 130Kw, and stir counterclockwise at 100Hz medium frequency for 20 minutes; Third stage: Increase the power of the medium frequency power supply to 240Kw, and stir clockwise at 90Hz for 20 minutes.

[0057] S6. After refining, return the crucible to the correct position, increase the medium frequency power supply to 280Kw to quickly heat up to the steel pouring temperature, turn on the atomization chamber fan and atomizing gas to start shaking the furnace for steel pouring, and collect the powder two hours after steel pouring is completed.

[0058] Comparative Example 1 This comparative example provides a method for suppressing inclusions in VIGA powder, using the same alloy grade as in Example 1.

[0059] The T-shaped slag baffle and melting crucible were prepared using the same method as in Example 1. The method for suppressing inclusions in VIGA powder was also the same as in Example 1, except that: In step S5, after the crucible is cleaned, it is not shaken towards the spout side for refining. First stage: the power of the medium frequency power supply is adjusted to the rated power of 230Kw, the vacuum degree of the melting chamber is evacuated to below 3Pa, and low frequency 3~5Hz clockwise stirring is used for 20min. Second stage: Reduce the power of the medium frequency power supply to 120Kw, and stir counterclockwise at 100Hz medium frequency for 20 minutes; Third stage: Increase the power of the medium frequency power supply to 240Kw, and stir clockwise at 100Hz for 20 minutes.

[0060] Comparative Example 2 This comparative example provides a method for suppressing inclusions in VIGA powder, using the same alloy grade as in Example 1.

[0061] The T-shaped slag baffle and melting crucible were prepared using the same method as in Example 1. The method for suppressing inclusions in VIGA powder was also the same as in Example 1, except that: In step S5, after the slag is cleared, the crucible is shaken towards the pouring nozzle to bring the molten steel surface close to the slag baffle. The crucible is tilted, and the lower edge of the slag baffle is controlled at a position 2-6 cm away from the molten steel surface for refining. The refining temperature is maintained at 1540℃ for 60 minutes.

[0062] Comparative Example 3 This comparative example provides a method for suppressing inclusions in VIGA powder, using the same alloy grade as in Example 1.

[0063] The same method as in Example 1 was used to prepare a T-shaped slag baffle and a melting crucible, except that the T-shaped slag baffle did not have a CaZrO3 coating.

[0064] The method for suppressing inclusions in VIGA powder is the same as in Example 1.

[0065] Comparative Example 4 This comparative example provides a method for suppressing inclusions in VIGA powder, using the same alloy grade as in Example 1.

[0066] The same method as in Example 1 was used to prepare a T-shaped slag baffle and a melting crucible, except that the material of the T-shaped slag baffle does not contain Cr2O3.

[0067] The method for suppressing inclusions in VIGA powder is the same as in Example 1.

[0068] Comparative Example 5 This comparative example provides a method for suppressing inclusions in VIGA powder, using the same alloy grade as in Example 1.

[0069] The same method as in Example 1 was used to prepare a T-shaped slag baffle and a melting crucible, except that the material of the T-shaped slag baffle does not contain ZrO2.

[0070] The method for suppressing inclusions in VIGA powder is the same as in Example 1.

[0071] Comparative Example 6 This comparative example provides a method for suppressing inclusions in VIGA powder, using the same alloy grade as in Example 2.

[0072] The T-shaped slag baffle and melting crucible were prepared using the same method as in Example 2. The method for suppressing inclusions in the VIGA powder was also the same as in Example 2, except that: In step S5, after the clarification, the crucible was not shaken towards the pouring nozzle side, and the refining was carried out at 1540℃ for 60 minutes.

[0073] The powders obtained in the examples and comparative examples were subjected to SEM analysis. Twenty fields of view were captured for each sample, with more than 400 particles per field of view. The proportion of surface-admixed particles to the total number of particles was statistically analyzed. Referring to GB / T 39251, "Characteristics of Additive Manufacturing Metal Powder Properties," the number of times the T-shaped slag baffle provided by this invention was used was statistically analyzed, and the results are shown in Table 1. Table 1. Data on slag-blocking effect and slag-blocking plate service life in the examples and comparative examples.

[0074] As can be seen from the data in Table 1, the method for suppressing inclusions in VIGA powder provided by this invention significantly reduces powder inclusions. Through the combined effects of the physical interception and adsorption of the T-shaped slag baffle and the VIGA smelting process, the content of non-metallic inclusions in the VIGA atomized powder is greatly reduced, improving powder purity. The T-shaped slag baffle provided by this invention, through material compounding and coating design, enables the slag baffle to withstand rapid heating and cooling of molten steel and prolonged high-temperature refining, making it less prone to cracking and peeling, and extending its service life.

[0075] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are exhaustively listed. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0076] For those skilled in the art, various modifications and improvements can be made without departing from the concept of the present invention, and these modifications and improvements are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A T-shaped slag-blocking device, characterized in that, The T-shaped slag-blocking device consists of a T-shaped slag-blocking plate and a smelting crucible with grooved inner walls; The T-shaped slag baffle plate consists of Al2O3, ZrO2, Cr2O3 materials and a CaZrO3 coating; Based on the total mass content of the materials, Al2O3 is 85-94%, ZrO2 is 5-10% and Cr2O3 is 1-5%.

2. The T-shaped slag-blocking device according to claim 1, characterized in that, The thickness of the CaZrO3 coating is 0.2~0.5 mm; The porosity of the coating is 5-8%.

3. The T-shaped slag-blocking device according to claim 1, characterized in that, The T-shaped slag baffle has a continuous upper and lower end, and its thickness is 1.5~3.5cm. The height of the lower end is 14~30cm, and the width is 22~29cm; The upper part of the T-shaped slag baffle plate has a height of 4~8cm and a width of 26~33cm.

4. The T-shaped slag-blocking device according to claim 1, characterized in that, The smelting crucible is cylindrical, and the crucible spout is made of prefabricated channels and refractory clay; Two grooves are provided on the inner wall of the crucible near the spout for installing slag baffles. The groove forms an angle of 40° to 75° with the horizontal plane.

5. The T-shaped slag-blocking device according to claim 4, characterized in that, The melting crucible has an inner diameter of 32-45cm, a wall thickness of 3-4cm, and a height of 75-100cm.

6. The T-shaped slag-blocking device according to claim 1, characterized in that, An expansion joint is reserved at the connection between the slag baffle plate and the crucible lining, and filled with high-purity alumina fiber felt.

7. A method for suppressing inclusions in VIGA powder, characterized in that, The method requires the use of the T-type slag-blocking device as described in any one of claims 1-6.

8. The method for suppressing inclusions in VIGA powder according to claim 7, characterized in that, The method includes the following steps: S1. Remove impurities from the surface of the T-shaped slag baffle and the smelting crucible; S2. Assemble the T-shaped slag-blocking device and install it inside the VIGA intermediate frequency coil for baking; S3. Load the raw materials into the furnace in a tight-to-loose manner from bottom to top. Do not load materials into the gap between the slag baffle and the crucible wall. Place 2-3 large pure nickel plates or master alloy ingots vertically close to the slag baffle. After closing the furnace lid, S4 and VIGA will draw a vacuum, and then start the medium frequency power supply to begin melting until the raw materials are clear. S5. After cleaning, shake the crucible toward the spout side to bring the molten steel surface close to the slag baffle plate, and refine the crucible in an inclined state. The refining temperature is 1530~1590℃, and the total refining time is 50~80min. S6. After refining, return the crucible to the correct position, quickly heat it to the casting temperature, and then turn on the atomization chamber fan and atomizing gas to start the furnace shaking and casting process.

9. The method for suppressing inclusions in VIGA powder according to claim 8, characterized in that, In step S2, the baking temperature is 300~600℃ and the baking time is 5~8h; In step S4, the melting chamber is evacuated to below 5 Pa. In the initial stage of melting, the power supply is controlled at 20% to 30% of the rated power for 15 to 30 minutes, and then the power is increased to 60% to 80%.

10. The method for suppressing inclusions in VIGA powder according to claim 8, characterized in that, In step S5, refining is divided into three stages, which are carried out continuously while the crucible is tilted. First stage: Adjust the power of the medium frequency power supply to 70%~80% of the rated power, evacuate the vacuum degree of the melting chamber to below 3Pa, and stir clockwise at a low frequency of 3~5Hz for 10~20 minutes; Second stage: Reduce the power of the medium frequency power supply to 40%~50% of the rated power, and stir counterclockwise at 100~150Hz for 15~30 minutes; Third stage: Increase the power of the medium frequency power supply to 70%~80% of the rated power, and stir counterclockwise for 12~25 minutes using medium frequency 90~150Hz.

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