A process for efficiently suppressing surface slag during the high-temperature alloy casting process

Abstract

This invention relates to the field of high-temperature alloy casting process, specifically a process for efficiently suppressing surface slag during the high-temperature alloy casting process. The process includes the following steps: (1) preparing a master alloy ingot with no oxide scale or other defects on the surface, the surface of which needs to be treated to expose a metallic luster; (2) casting the alloy ingot using oxide ceramic crucibles such as magnesium oxide, zirconium oxide, aluminum oxide, or magnesium-aluminum crucibles, with material added to either a cold or hot crucible; (3) before adding the alloy ingot to the crucible, the vacuum needs to be reduced to below 10 Pa, and after adding the material, high-power electricity is supplied to the alloying cleaning process; (4) during alloying cleaning, the surface slag percentage is less than 5%; (5) after alloying cleaning, the temperature is directly raised to the casting temperature for casting the parts. Using the method of this invention to cast high-temperature alloys can effectively suppress surface slag during the secondary casting process, reduce part scrap caused by slag, and improve the production efficiency and pass rate of high-temperature alloy parts.

Description

Technical fields:

[0001] This invention relates to the field of high-temperature alloy casting process, specifically a process for efficiently suppressing surface slag during the high-temperature alloy casting process. Background technology:

[0002] High-temperature alloys are key materials for manufacturing core components of advanced aero-engines, and their purity and performance stability are important indicators determining the manufacturing cost and reliability of aero-engine components. The purity of cast high-temperature alloys is mainly controlled in two aspects: firstly, the content of trace harmful impurity elements in the alloy; and secondly, the content of inclusions during the smelting or secondary casting process. In recent years, due to advancements in equipment and corresponding improvements in smelting levels, the content of impurity elements in high-temperature alloys can be controlled to low levels. For example, elements such as O, N, and S can be reduced to below 10 ppm, and there is evidence that reducing harmful elements in the alloy improves its performance. Furthermore, inclusions in the alloy can become crack initiation points during deformation, reducing the alloy's mechanical properties, such as tensile properties, creep resistance, and fatigue performance. Therefore, strict control is necessary in high-temperature alloys.

[0003] Currently, methods for controlling inclusion formation mainly involve controlling raw materials and ceramic auxiliary materials during the smelting process, and filtering slag through systems such as chutes during the casting process to reduce inclusions in the alloy. For a long time, surface slag has been prone to occur during the secondary casting of high-temperature alloys. High-temperature refining is typically used to reduce surface slag, but this reduces casting production efficiency and makes it difficult to precisely control the content of volatile elements (such as Al, Ti, and Cr) and key beneficial trace elements (such as C, La, Y, and Ce), thus affecting the final alloy properties. Furthermore, when there is a large amount of surface slag in the alloy, poor slag control can severely impact the yield and reliability of the produced parts. Summary of the Invention:

[0004] The purpose of this invention is to provide a highly efficient process for suppressing surface slag during the high-temperature alloy casting process. This method utilizes a periodic furnace or a semi-continuous furnace for casting in different high-temperature alloy systems, and it has a significant effect on suppressing slag. It is highly operable and can be used in actual production to suppress slag.

[0005] The technical solution of this invention is:

[0006] A highly efficient process for suppressing surface slag during the high-temperature alloy melting and casting process involves using pure high-temperature alloy ingots in an oxide ceramic crucible, in a periodic or semi-continuous furnace, and controlling the feeding method, feeding time, and power supply to suppress surface slag after high-temperature alloying and cleaning. The surface slag area during alloying and cleaning is less than 5%.

[0007] The aforementioned process for efficiently suppressing surface slag during the high-temperature alloy melting and casting process requires a leakage rate of less than 20 Pa / h and an ultimate vacuum degree of less than 10 Pa for periodic or semi-continuous furnaces.

[0008] The aforementioned process for efficiently suppressing surface slag during the high-temperature alloy casting process involves cutting the alloy ingot using a grinding wheel, circumferential cutting, sawing, or wire cutting. After cutting, the surface must undergo spark-free polishing to ensure it is free of oil and that the entire surface of the alloy ingot is exposed with a metallic luster.

[0009] The aforementioned process for efficiently suppressing surface slag during the high-temperature alloy melting and casting process utilizes an isostatically preformed crucible or a crucible prepared by a knotting process, with the crucible material being magnesium oxide, aluminum oxide, zirconium oxide, or magnesium-aluminum crucible material.

[0010] The aforementioned process for efficiently suppressing surface slag during the high-temperature alloy melting and casting process utilizes a turret for feeding in a periodic furnace or a semi-continuous furnace.

[0011] The process for efficiently suppressing surface slag during the high-temperature alloy melting and casting process involves adding a high-temperature alloy ingot when the vacuum degree reaches below 10 Pa. After the alloy ingot enters the crucible, power is supplied, with a power requirement of 20-100 kW. After the alloy is opened up, a smaller power of 1-30 kW is used until the alloy is cleared.

[0012] The aforementioned process for efficiently suppressing surface slag during the high-temperature alloy melting and casting process involves an alloy ingot made of high-temperature alloy material, which contains one or more of the elements Ni, Co, Cr, Mo, W, Al, Ti, Nb, Ta, C, B, Zr, and Hf.

[0013] The aforementioned process for efficiently suppressing surface slag during the high-temperature alloy melting and casting process involves directly raising the temperature to the casting temperature after alloying and cleaning, followed by casting, without the need for high-temperature refining.

[0014] The aforementioned process for efficiently suppressing surface slag during the high-temperature alloy casting process successfully suppresses slag during the secondary casting of high-temperature alloys. This process can be used for the production of high-temperature alloy castings or the preparation of performance test samples, thereby improving the production efficiency and reliability of high-temperature alloy castings.

[0015] The design concept of this invention is:

[0016] First, a master alloy ingot with a surface free of oxide scale and other defects is prepared. The surface of the master alloy ingot needs to be treated to expose a metallic luster to ensure that the alloy ingot surface is free of oxidation, thereby avoiding the possibility of introducing slag. Second, using a periodic furnace or semi-continuous furnace, after the vacuum reaches the target value, the material is discharged through a turret. The alloy ingot is then melted and cast using oxide ceramic crucibles such as magnesia, zirconium oxide, alumina, or magnesium-aluminum crucibles. Cold or hot crucibles are used for discharging. Before adding the master alloy ingot to the crucible, the vacuum needs to be evacuated to below 2 Pa. After the material is added, high-power electric heating is used. After the alloy melts, the power is reduced to low power until the alloy is cleared, minimizing the possibility of oxidation and slag formation. Finally, after clearing the alloy, the temperature is directly increased to the casting temperature before casting the parts. This significantly reduces the tendency for surface slag formation during the secondary melting and casting process of high-temperature alloys.

[0017] The advantages and beneficial effects of this invention are:

[0018] 1. Traditional methods reduce surface slag through high-temperature refining and mechanical treatment, but the effect of suppressing slag is poor. Furthermore, high-temperature refining increases the difficulty of controlling volatile elements in the alloy, thus affecting the alloy's performance. This invention addresses the causes of slag formation and, through process innovation, develops a new method for suppressing surface slag on secondary casting high-temperature alloys. This method significantly controls the formation of surface slag.

[0019] 2. This invention utilizes a periodic furnace or a semi-continuous furnace for operation, requiring no additional modifications to the equipment.

[0020] 3. This invention can be used for surface slag control in the melting and casting process of all high-temperature alloy materials and other non-ferrous metal materials. Attached image description:

[0021] Figure 1 (a)-(d) are morphological images of the surface of the alloy as it sequentially changes from open to clear during the melting of M951 alloy in a 10kg periodic furnace using the process of the present invention.

[0022] Figure 2 This image shows the surface morphology of the melt after alloying and cleaning when casting high Al and Ti content alloy K417G in a 10kg periodic furnace using the process of this invention.

[0023] Figure 3 This image shows the morphology of the surface melt during the clearing of M951 alloy in a 25kg semi-continuous furnace using the process of this invention. Detailed implementation method:

[0024] In specific implementation, the process of suppressing slag formation during the high-temperature alloy casting process according to the present invention is as follows:

[0025] First, high-temperature alloy ingots of the target composition are prepared by vacuum induction melting. The surface of the alloy ingots is then polished to remove defects such as oxide inclusions and surface oxide scale. The alloy ingots are then cut using an abrasive wheel saw, and the cut surfaces are polished. The polished alloy ingots are then fixed in the turret of a semi-continuous or periodic furnace.

[0026] Next, the furnace is evacuated. The equipment is equipped with a mechanical pump, a Roots pump, and a diffusion pump. Once the vacuum level reaches below 10 Pa, the alloy ingot is placed into a crucible via a turret. The crucible can be either cold or hot. After the alloy ingot is placed in the crucible, it is heated by electricity. Once the alloy ingot has melted and cleared, the electricity is continued to raise the temperature until the casting temperature is reached. Then, the molten alloy is poured into the mold shell.

[0027] The mold shells for the periodic furnace are placed into the furnace in advance, while the mold shells for the semi-continuous furnace are placed into the furnace after the melting reaches the pouring temperature.

[0028] The present invention will now be further described in detail through embodiments.

[0029] Example 1

[0030] In this embodiment, the typical high-tungsten casting high-temperature alloy M951 is selected and melted in a 10kg periodic furnace. M951 nickel-based casting high-temperature alloy ingots are prepared according to the method described in the technical solution of this invention. Abrasive wheel saws are used for cutting, and after cutting, abrasive band saws are used to remove all defects and oxide scale from the surface of the alloy ingots. The alloy ingots are fixed onto the turret of the 10kg periodic furnace, and the turret is used for feeding. A preheated 900℃ mold shell is placed into the periodic furnace beforehand. After the furnace is closed and evacuated until the pressure inside reaches 2Pa, the M951 alloy ingot is placed into a magnesium oxide ceramic crucible using the turret, and then electrically heated at a power of 40kW. After 6 minutes of heating, the bottom of the alloy ingot begins to melt; then a lower power of 20kW is used, and after 2 minutes of melting, the alloy ingot is completely melted. Figure 1 As shown, the surface melt evolution morphology of M951 alloy during the melting and clearing process is as follows: there is no slag on the surface after alloy clearing. After alloy clearing, the temperature is directly increased to the casting temperature before casting the parts.

[0031] Example 2

[0032] In this embodiment, the typical high-Al, Ti content casting high-temperature alloy K417G was selected and melted and cast using a 10kg periodic furnace. K417G alloy ingots were prepared according to the method described in the technical solution of this invention, and cut using wire cutting. After cutting, surface contamination caused by wire cutting was removed. The alloy ingot was fixed onto the turret of the 10kg periodic furnace, and the turret was used for feeding. A preheated 950℃ mold shell was placed into the periodic furnace. After evacuating the furnace to a pressure of 1Pa, the K417G alloy ingot was placed into a zirconia ceramic crucible using the turret, and then electrically heated at a power of 40kW. After 7 minutes of heating, the alloy ingot began to melt. The power was then reduced to 25kW, and after 2 minutes of melting, the alloy was cleared. The morphology after alloy clearing is shown in the figure. Figure 2 .Depend on Figure 2 As can be seen, there is no slag on the surface after alloying and cleaning. After alloying and cleaning, the temperature is directly increased until the casting temperature is reached, and then the parts are cast.

[0033] Example 3

[0034] In this embodiment, a 25kg semi-continuous furnace was selected to melt and cast 20kg of high-temperature alloy M951. M951 alloy ingots were prepared according to the method described in the technical solution of this invention. The alloy ingots were cut using a grinding wheel saw, and the surface of the alloy ingots was treated with a grinding wheel to remove surface oxide scale and other external contaminants. The alloy ingots were fixed onto a turret, and the turret was used for charging. After the furnace was evacuated to a pressure of 1Pa inside the semi-continuous furnace, the alloy ingots were added to a magnesia ceramic crucible. The power supply was 50kW, and after 10 minutes of power supply, the alloy ingots were opened. The power supply was then reduced to 30kW, and after 5 minutes of opening, the alloying was cleared. The morphology of the slag after alloying was observed... Figure 3 .Depend on Figure 3 It can be seen that the surface slag area during alloying cleaning is 3%. The preheated shell at 950℃ is placed in a semi-continuous furnace, and casting is carried out after the casting temperature reaches the set temperature.

[0035] The results of the examples show that the method of the present invention for casting high-temperature alloys can effectively suppress surface slag during the secondary casting process of the alloy, reduce the scrap of parts caused by slag, and improve the production efficiency and pass rate of high-temperature alloy parts.

Claims

1. A process for efficiently suppressing surface slag during the high-temperature alloy melting and casting process, characterized in that, Using pure high-temperature alloy ingots, in an oxide ceramic crucible, in a periodic or semi-continuous furnace, by controlling the feeding method, feeding time, and power supply process, the purpose of suppressing the floating slag on the alloy surface after high-temperature alloying and cleaning is achieved, with the surface floating slag area being less than 5% during alloying and cleaning; The leakage rate of the periodic furnace or semi-continuous furnace should be less than 20 Pa / h, and the ultimate vacuum degree should be less than 10 Pa. The alloy ingot is cut using grinding wheel, circumferential cutting, sawing or wire cutting methods. After cutting, the surface is required to be polished without sparks, and the surface is free of oil. The entire surface of the alloy ingot should show a metallic luster. Crucibles prepared using isostatic pressing pre-formed crucibles or knotting processes, with crucible materials being magnesium oxide, aluminum oxide, zirconium oxide, or magnesium-aluminum crucible materials; Feeding is carried out using a turret in a periodic furnace or a semi-continuous furnace; When the vacuum degree reaches below 10Pa, add a high-temperature alloy ingot. After the alloy ingot enters the crucible, power is supplied. The power supply power is required to be 20~100kW. After the alloy is opened, switch to a small power of 1~30kW until the alloy is clear. After alloying and cleaning, the temperature is directly raised to the casting temperature, and then cast, without the need for high-temperature refining.

2. The process for efficiently suppressing surface slag during the high-temperature alloy casting process according to claim 1, characterized in that, The alloy ingot is a high-temperature alloy material containing one or more of the elements Ni, Co, Cr, Mo, W, Al, Ti, Nb, Ta, C, B, Zr, and Hf.

3. The process for efficiently suppressing surface slag during the high-temperature alloy casting process according to claim 1, characterized in that, This process successfully suppresses slag during the secondary casting of high-temperature alloys, and can be used for the production of high-temperature alloy castings or the preparation of performance test samples, thereby improving the production efficiency and reliability of high-temperature alloy castings.

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