Advanced solidification forming method for moving blade of high-power gas turbine

Abstract

The invention discloses an advanced solidification forming method for a high-power gas turbine moving blade. An existing moving blade is complex in shape and uneven in wall thickness, and defects such as shrinkage cavities, shrinkage porosity and cracks are prone to occurring in the casting process. The method comprises the steps of mold making, shell making, vacuum melting and pouring and vacuum heat treatment, all-silica sol is adopted as a binding agent of the coating and is used in cooperation with a refiner, so that the high-temperature strength and the deformation resistance of the shell are improved, and surface grain refinement of a casting is achieved. An advanced vacuum smelting and vacuum pouring method is adopted for the high-temperature mother alloy, and strict control over the high-temperature mother alloy is completed in cooperation with reasonable parameters of the high-temperature mother alloy. A vacuum heat treatment furnace is adopted for carrying out vacuum heat treatment on the blade, and the excellent internal structure and performance of the casting are achieved through primary solid solution treatment and secondary aging treatment, so that various physical and chemical requirements of the casting are met. The method is applied to the field of advanced solidification forming of gas turbine moving blades.

Description

Technical Field

[0001] The present invention relates to the field of moving blades of gas turbines, and particularly to an advanced solidification forming method for high-power moving blades of gas turbines. Background Art

[0002] The moving blade of a gas turbine is one of the core components of the gas turbine. Its working environment is extremely harsh, and it needs to withstand complex stresses of high temperature, high pressure, and high-speed rotation. The moving blade is a key component of the gas turbine turbine.

[0003] The manufacturing quality of the moving blade directly affects the performance and service life of the gas turbine. The investment casting technology is adopted for the manufacturing process of the moving blade. However, due to the complex shape and uneven wall thickness of the moving blade, defects such as shrinkage cavities, shrinkage porosity, and cracks are likely to occur during the casting process. The complex shape and uneven wall thickness of the moving blade result in inconsistent shrinkage degrees of each part during the cooling process. The thick-walled part cools slowly, and tensile stress will be generated on the already cooled thin-walled part during shrinkage. When this thermal stress exceeds the strength limit of the material, cracks will occur. At the same time, volume shrinkage during solidification will also generate stress. In the moving blade with a complex shape, this stress is unevenly distributed, and cracks are likely to occur at the stress concentration sites, such as corners and sudden changes in wall thickness. Moreover, due to different solidification times at different parts, the shrinkage of the later solidified part will generate tensile stress on the earlier solidified part, which is also one of the factors leading to cracks.

[0004] The existence of shrinkage cavities and shrinkage porosity will reduce the effective load-bearing area of the blade. When subjected to external forces, stress concentration phenomena will occur around these holes, reducing mechanical property indexes such as the tensile strength and yield strength of the blade. Cracks directly damage the integrity of the blade, causing the blade to break under a relatively low external force. Moreover, the stress concentration coefficients at the defects such as shrinkage cavities, shrinkage porosity, and cracks are relatively high. Under the action of alternating stress, these parts are easily the source points of fatigue cracks, accelerating the fatigue crack propagation speed of the blade, thus greatly shortening the fatigue life of the blade.

[0005] The present invention solves the problem that the development of existing moving blades of gas turbines is slow and it is difficult to meet the standard in various physical and chemical indexes, and thus provides an advanced solidification forming method for high-power moving blades of gas turbines. Summary of the Invention

[0006] In order to solve the problem that due to the complex shape and uneven wall thickness of the moving blade, defects such as shrinkage cavities, shrinkage porosity, and cracks are likely to occur during the casting process, the present invention provides an advanced solidification forming method for high-power moving blades of gas turbines.

[0007] The technical solution of the present invention is as follows:

[0008] An advanced solidification forming method for high-power moving blades of gas turbines, the method comprising the following steps:

[0009] Step 1: Mold making:

[0010] Step 1.1: On a wax injection machine, select medium-temperature wax material and press it according to the mold of the required gas turbine moving blade. After injecting wax, keep the pressure in the mold. Take out the wax mold after maintaining the pressure for 50 - 60 s.

[0011] Step 1.2: Modify the wax mold to make it defect-free.

[0012] Step 1.3: Assemble the gating and risering system on the wax mold.

[0013] Step 2: Shell making:

[0014] Step 2.1: On the outer surface of the wax mold obtained in Step 1, make a shell using a surface layer coating with silica sol as the binder.

[0015] Step 2.2: Use a surface layer coating with a surface refiner for the surface layer of the shell, use corundum sand for the surface layer powder of the second layer, and use mullite powder for the third layer and the back layer of the shell to make a high-strength refractory shell.

[0016] Step 2.3: Air-dry the shell until it reaches the specified strength, then dewax it with steam. The dewaxing temperature is 140 - 160 °C, the pressure head is 0.4 - 0.6 MPa, and the pressure maintaining time is 10 - 15 minutes.

[0017] Step 3: Vacuum melting and pouring:

[0018] Step 3.1: Wrap the insulation felt around the shell described in Step 2.

[0019] Step 3.2: Bake the shell, and the baking temperature is 850 - 950 °C.

[0020] Step 3.3: Use a vacuum induction casting furnace to vacuum smelt and vacuum pour the metal raw materials used for casting the gas turbine moving blade respectively to obtain the required casting.

[0021] Step 3.4: After pouring is completed, keep the obtained casting in a vacuum state for 10 - 15 minutes and then take it out, and place it in an incubator for cooling.

[0022] Step 4: Vacuum heat treatment:

[0023] Step 4.1: Perform solution treatment on the casting obtained in Step 3.

[0024] The solution treatment process is: the solution temperature is 1150 - 1170 °C, then keep it warm for 3 - 3.5 hours, and then cool it by blowing argon gas.

[0025] Step 42: After solution treatment is completed, perform the first aging treatment on the casting. The temperature of the first aging treatment is 1050 - 1070 °C, and the holding time is 4 - 4.5 hours;

[0026] Step 43: After aging treatment, cool by blowing argon gas;

[0027] Step 44: Perform the second aging treatment on the casting. The temperature of the second aging treatment is 840 - 860 °C, and the holding time is 16 - 17 hours. After cooling by blowing argon gas again, the described gas turbine moving blade is obtained.

[0028] Furthermore, the vacuum smelting in Step 33 includes the following steps:

[0029] Step 331: Evacuate the vacuum:

[0030] Start the vacuum system to evacuate the vacuum furnace. After pumping out the air in the furnace, a vacuum state is achieved;

[0031] Step 332: Load the materials:

[0032] First, load the metal raw materials for manufacturing the moving blade into the crucible of the vacuum induction casting furnace;

[0033] Step 333: Supply power to melt:

[0034] During the charging in the vacuum state, add the metal raw materials into the crucible. Through the principle of electromagnetic induction, eddy currents are generated in the metal raw materials, causing the metal raw materials to quickly heat up and melt. During the melting process, control the power supply according to the melting point and characteristics of the metal;

[0035] Step 334: Refine:

[0036] Remove the oxygen in the molten metal and allow the hydrogen gas to escape using the vacuum environment;

[0037] Furthermore, the vacuum pouring in Step 33 includes the following steps:

[0038] Step 331: Preheat the mold shell:

[0039] Heat the mold shell. The heating temperature is 850 - 950 °C to enable the molten metal to better fill the complex-shaped parts of the mold shell;

[0040] Step 332: Transfer and position in the furnace:

[0041] After the metal is melted in the crucible, keep the position unchanged. When pouring, turn the crucible over and pour. Move the position of the mold shell and dock it with the pouring gate of the crucible to ensure successful pouring and accurately dock the pouring gate with the gate of the mold shell;

[0042] Step 333: Start pouring:

[0043] After the docking is completed, tilt the crucible for pouring, and quickly pour the molten metal into the mold shell. The pouring speed should be controlled according to the size, shape of the mold shell and the characteristics of the molten metal;

[0044] Step Three Four: Post-pouring treatment:

[0045] After the molten metal is completely poured into the mold shell, keep it in vacuum for 10 - 15 minutes, then take out the casting together with the mold shell from the furnace, put it into a heat preservation box after taking out, and the unpacking time ≥ 5h for subsequent cleaning and processing.

[0046] Furthermore, the solution treatment in Step Four includes the following steps:

[0047] Step Four One: Heating:

[0048] Put the blade casting into a vacuum heat treatment furnace for heat treatment;

[0049] Step Four Two: Insulation:

[0050] After the blade casting reaches the solution temperature, it needs to be insulated for 2 - 6 hours;

[0051] Step Four Three: Cooling:

[0052] Cooling is carried out by flushing argon gas in the furnace;

[0053] Furthermore, the melting process of the vacuum induction casting furnace in Step Three Three is as follows;

[0054] Load and power on the vacuum furnace, after the melting period and refining period, load it into the mold shell, evacuate the vacuum and carry out pouring under the condition that the vacuum degree is not greater than 1Pa, then take it out and put it into a heat preservation box.

[0055] Furthermore, the temperature of vacuum melting and pouring of the vacuum induction casting furnace in Step Three Three is 1470 - 1520 °C, and the speed of vacuum pouring is 3 - 8 seconds per group.

[0056] Furthermore, the temperature of the medium-temperature wax in Step One One is 70 - 100 °C.

[0057] Furthermore, the process method of Step One Two: correcting the wax mold to make it defect-free includes the following steps:

[0058] Step One Two One: Surface repair:

[0059] For pits or pores, use repair wax to heat and melt for filling, and for scratches, gently wipe with a soft cloth or fine sandpaper to smooth the scratches;

[0060] Step One Two Two: Removing flash and burrs:

[0061] Trim the excess wax at the edge of the wax mold. During the operation, keep close to the wax mold body to ensure that the trimmed edge is flat and smooth.

[0062] Steps 1, 2, and 3: Dimension and shape correction:

[0063] Apply a layer of molten wax evenly on its surface to increase the thickness and reach the standard size.

[0064] Furthermore, in step 2 and 3, when the investment shell reaches the specified strength, the strength required for the investment shell during high-temperature roasting and pouring molten metal is the high-temperature strength.

[0065] The present invention has the following effects compared with the prior art:

[0066] In the mold-making process of the present invention, medium-temperature wax is used to press the wax mold. The operator uses 3D design software to complete the 3D solid models of the casting and the gating system. Then, by computer-simulating the cooling and solidification sequence of the pouring process, the hot spot location of the casting and the possible locations of casting defects are determined to achieve the function of optimizing the gating system. The coating uses all-silica sol as the binder and is used in combination with a refiner to enhance the high-temperature strength and anti-deformation ability of the investment shell and make the surface grains of the casting refined.

[0067] The present invention adopts advanced vacuum smelting and vacuum pouring methods for high-temperature superalloys and completes strict control over them with reasonable parameters. A vacuum heat treatment furnace is used to perform vacuum heat treatment on the blades. Through one solution treatment and two aging treatments, excellent internal structures and properties of the castings are achieved to meet the various physical and chemical requirements of the castings:

[0068] The specific physical and chemical requirements are as follows: Chemical composition: C: 0.04 - 0.09; Cr: 15.4 - 16.3; Co: 10.0 - 11.5; Ti: 4.2 - 5.0; Fe: ≤0.5; Mn: ≤0.30; Si: ≤0.30;

[0069] High-temperature mechanical properties: Tensile strength: At 900°C, the tensile strength is not less than 640 MPa; Elongation: Not less than 8%; Creep strength: At 900°C, the tensile stress is not less than 270 MPa and the time is not less than 100 h;

[0070] Low-magnification grain size: At the exhaust side of the blade body 1, it is not more than grade 5 (2.82 mm), and in other parts, it is not more than grade 7 (5.64 mm). Description of the Drawings

[0071] Figure 1 is the front view of the moving blade of the gas turbine of the present invention.

[0072] Figure 2 is the side view of the moving blade of the gas turbine of the present invention.

[0073] Figure 3 It is a schematic structural diagram of the melting and pouring of the moving blade of the gas turbine of the present invention. Specific embodiments

[0074] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0075] Specific embodiment one: Combine Figure 1 — Figure 3 To illustrate this embodiment, an advanced solidification forming method for the moving blade of a high-power gas turbine is provided. The method includes the following steps:

[0076] An advanced solidification forming method for the moving blade of a high-power gas turbine, the method including the following steps:

[0077] Step one: Mold making:

[0078] Step 11: On a wax pressing machine, select medium-temperature wax material and press according to the mold of the required moving blade of the gas turbine. After injecting wax, keep the pressure in the mold. Take out the obtained wax mold after keeping the pressure for 50 - 60 s;

[0079] Step 12: Correct the wax mold to make it defect-free;

[0080] Step 13: Assemble the riser on the wax mold;

[0081] Step two: Shell making:

[0082] Step 21: On the outer surface of the wax mold obtained in step one, make a shell using a surface layer coating with silica sol as the binder;

[0083] Step 22: Make a high-strength refractory shell using a surface layer coating with a surface refining agent added to the surface layer of the shell, corundum sand for the surface layer powder of the second layer, and mullite powder for the third layer and the backing layer of the shell;

[0084] Step 23: Air-dry the shell until it reaches the specified strength, then use steam for dewaxing. The dewaxing temperature is 140 - 160 °C, the pressure head is 0.4 - 0.6 MPa, and the pressure holding time is 10 - 15 minutes;

[0085] Step three: Vacuum melting and pouring:

[0086] Step 31: Wrap a heat-insulating felt outside the shell described in step two;

[0087] Step 32: Bake the shell, and the baking temperature is 850 - 950 °C;

[0088] Step 33: The metal raw materials used for casting the gas turbine moving blades are subjected to vacuum smelting and vacuum pouring respectively in a vacuum induction casting furnace to obtain the required castings;

[0089] Step 34: After pouring is completed, the obtained casting is kept in a vacuum state for 10 - 15 minutes and then taken out and placed in a heat preservation box for cooling;

[0090] Step 4: Vacuum heat treatment:

[0091] Step 41: Solution treatment is carried out on the casting obtained in Step 3;

[0092] The solution treatment process is: the solution temperature is 1150 - 1170 °C, then keep warm for 3 - 3.5 hours, and then cool by blowing argon gas;

[0093] Step 42: After the solution treatment is completed, the casting is subjected to the first aging treatment. The temperature of the first aging treatment is 1050 - 1070 °C, and the heat preservation time is 4 - 4.5 hours;

[0094] Step 43: After the aging treatment, cool by blowing argon gas;

[0095] Step 44: The casting is subjected to the second aging treatment. The temperature of the second aging treatment is 840 - 860 °C, and the heat preservation time is 16 - 17 hours. After cooling by blowing argon gas again, the described gas turbine moving blade is obtained.

[0096] The wax pattern manufactured according to the said Step 13 is assembled with risers and gating systems:

[0097] First of all, before assembly, the wax pattern, gating system and riser should be inspected to ensure that their surface quality is good and there are no obvious defects. The gating system is connected to the wax pattern with bonding wax to ensure that the connection between the gating system and the wax pattern is firm and well - sealed, preventing metal liquid leakage or vacuum pouring during the subsequent shell - making and pouring processes. The riser is placed above or on the side of the thick - wall part. When assembling the riser, ensure that the connection is tight, and it is necessary to ensure that the riser provides enough volume of shrinkage - compensating metal liquid to allow the gas to escape smoothly.

[0098] Specific Embodiment 2: Combined with Figure 1 — Figure 3 This embodiment is described. An advanced solidification forming method for a high - power gas turbine moving blade of this embodiment includes the following steps:

[0099] On the outer surface of the wax mold obtained in Step 1, a shell mold is made with a silica sol binder. The first layer of the shell mold is a refiner, and the powders of the second and third layers of the shell mold are made of mullite sand powder to form a high-strength refractory coating, which can significantly improve the surface quality of the shell mold. The refiner is cobalt aluminate added to the surface coating, making the surface of the shell mold smoother and more delicate. The second and third layers use mullite sand powder to make a high-strength refractory coating. Mullite sand powder has a high refractoriness and can maintain good stability at high temperatures. When the molten metal (such as high-temperature alloy steel liquid) is poured into the shell mold, the coating made of mullite sand powder can effectively resist high temperatures, prevent the shell mold from melting or softening, and ensure the integrity of the shell mold.

[0100] Then, the shell mold is air-dried until it reaches the specified strength, and then steam dewaxing is carried out (when the shell mold is made, the wax mold needs to be removed, which is achieved by steam dewaxing. The principle is to use high-temperature steam to melt the wax mold and let it flow out of the shell mold. First, the shell mold with the wax mold is placed in a dewaxing kettle, and after closing the kettle door, high-temperature steam is introduced. Generally, the steam temperature is about 120 - 150 °C. During this process, the steam will penetrate into the interior of the shell mold, and the wax mold will change from solid to liquid when heated. Since the density of the liquid wax is less than that of water, it will flow out of the shell mold through channels such as the gates and risers of the shell mold under the action of steam pressure.

[0101] Moreover, the speed of steam dewaxing is also important. To ensure that the shell mold can maintain good strength and integrity after dewaxing, usually after dewaxing, the shell mold is baked, for example, to remove possible residual wax traces on the surface of the shell mold, etc., to prepare for subsequent pouring.), the dewaxing temperature is 140 - 160 °C, the pressure head is 0.4 - 0.6 MPa, and the pressure holding time is 10 - 15 minutes;

[0102] Specific Embodiment 3: Combining Figure 1 — Figure 3 To illustrate this embodiment, an advanced solidification forming method for the moving blades of a high-power gas turbine in this embodiment includes the following steps:

[0103] According to the silica sol binder in shell making in Step 2, a shell mold is made:

[0104] Dipping coating:

[0105] First, the wax mold assembled with gates and risers is immersed in the silica sol binder. Silica sol is a colloidal solution of nano-scale silica particles in water, and it can adhere well to the surface of the wax mold. During dipping coating, it is necessary to ensure that the wax mold is completely immersed, and the dipping coating speed should be appropriate to avoid generating bubbles. Because bubbles will form holes on the surface of the shell mold, affecting the quality of the shell mold. For example, for the wax mold of a moving blade with a complex shape, it may be necessary to adjust the dipping coating angle to ensure that each curved surface of the blade can be evenly coated with the binder.

[0106] Sand Spraying:

[0107] After dip - coating the binder, sand spraying should be carried out immediately. The purpose of sand spraying is to increase the strength and thickness of the shell mold. Corundum sand is usually used. For the outer surface of the wax pattern, the particle size of the sand for spraying should be selected according to the requirements of the shell mold. Generally, finer sand grains are used first. For the surface layer, 80 - mesh corundum is used, which can make the surface of the shell mold smoother and is beneficial to subsequent processes. When spraying sand, it is necessary to ensure that the sand grains evenly cover the binder. For the complex - shaped parts of the moving blades, it may be necessary to shake or rotate the wax pattern to enable the sand grains to enter the concave surfaces and gaps of the blades.

[0108] Drying and Hardening:

[0109] The shell mold after sand spraying needs to be dried and hardened. During the drying process of the silica sol binder, the moisture gradually evaporates, and the silica particles gradually aggregate and form a gel structure, thus hardening the shell mold. The drying temperature and humidity should be well - controlled. Generally, the temperature is 18 - 22 °C, and the relative humidity is 40% - 60% which is more appropriate. The drying time depends on the thickness of the shell mold and environmental conditions, usually taking several hours or even longer. For thicker shell molds or environments with higher humidity, the drying time should be appropriately extended. During this process, the strength of the shell mold will gradually increase, providing a basis for the production of multi - layer shell molds.

[0110] Fabrication of Multi - layer Shell Molds:

[0111] To meet the casting requirements, multi - layer shell molds are usually fabricated. Repeat the above processes of dip - coating, sand spraying, and drying and hardening. Generally, 10 layers of shell molds need to be fabricated. The particle size of the sand grains for each layer can gradually increase. For example, 30 - 60 - mesh sand can be used for the second layer, and the last layer is the sealant layer, which only dips in the material without sand spraying. This can make the shell mold have both good surface quality and sufficient strength to withstand the pouring of molten metal. When fabricating multi - layer shell molds, special attention should be paid to the bonding quality between each layer to ensure the integrity and strength of the overall shell mold.

[0112] Specific Embodiment Four: Combination Figure 1 — Figure 3 This embodiment is described. An advanced solidification forming method for the moving blades of a high - power gas turbine in this embodiment includes the following steps:

[0113] The method of vacuum pouring in step three:

[0114] Shell Mold Pre - heating:

[0115] Heat the shell mold, and the heating temperature is 1050 °C to improve the fluidity of the molten metal so that the molten metal can better fill the complex - shaped parts of the shell mold;

[0116] In - furnace Transfer and Positioning:

[0117] Tilt the crucible for pouring to accurately align the pouring port with the gate of the mold shell;

[0118] Start pouring:

[0119] After the docking is completed, tilt the crucible for pouring and pour the molten metal quickly. The pouring speed should be controlled according to the size and shape of the mold shell and the properties of the molten metal.

[0120] Treatment after pouring:

[0121] When the molten metal is completely poured into the mold shell, keep it in a vacuum for 10 - 15 minutes, then take out the casting together with the mold shell from the furnace and put it into a heat preservation box. The time to open the box is ≥5h, and then carry out subsequent cleaning and processing.

[0122] Specific embodiment five: Combined with Figure 1 — Figure 3 Describe this embodiment. An advanced solidification forming method for the moving blades of a high-power gas turbine in this embodiment. The solution treatment in step four:

[0123] Step four one one: Heating:

[0124] First, put the blade casting into a suitable heating device. The heat treatment device uses a vacuum heat treatment furnace;

[0125] Step four one two: Insulation:

[0126] After reaching the solution temperature, insulation is required, and the insulation time is 2 - 6 hours;

[0127] Step four one three: Cooling:

[0128] Cooling is carried out by the method of in-furnace cooling and argon is filled to avoid crack generation.

[0129] Specific embodiment six: Combined with Figure 1 — Figure 3 Describe this embodiment. An advanced solidification forming method for the moving blades of a high-power gas turbine in this embodiment. The melting process of the vacuum induction casting furnace in step three is as follows;

[0130] Charge and power on the vacuum furnace. After the melting period and refining period, load it into the mold shell, evacuate the air, and carry out pouring under the condition that the vacuum degree is not greater than 1 Pa, then take it out and put it into a heat preservation box.

[0131] Specific embodiment seven: Combined with Figure 1 — Figure 3 Describe this embodiment. An advanced solidification forming method for the moving blades of a high-power gas turbine in this embodiment. The temperature of the vacuum melting and pouring in the vacuum induction casting furnace in step three is 1470 - 1520 °C, and the speed of vacuum pouring is 3 - 8 seconds per group.

[0132] Embodiment VII: Combining Figure 1 — Figure 3 Describe this embodiment. An advanced solidification forming method for the moving blades of a high-power gas turbine in this embodiment, where the blade body 1, the upper rim plate 2, the lower rim plate 3 and the blade root are integrally formed.

[0133] Embodiment VIII: Combining Figure 1 — Figure 3 Describe this embodiment. An advanced solidification forming method for the moving blades of a high-power gas turbine in this embodiment, where the moving blade of the gas turbine is a turbine moving blade, and the structure of the turbine moving blade is a shrouded moving blade, the maximum length of the blade is 410 mm, and the length of the blade body is 330 mm.

[0134] Embodiment VIII: Combining Figure 1 — Figure 3 Describe this embodiment. An advanced solidification forming method for the moving blades of a high-power gas turbine in this embodiment,

[0135] Specifically: Chemical composition: C: 0.04 - 0.09; Cr: 15.4 - 16.3; Co: 10.0 - 11.5; Ti: 4.2 - 5.0; Fe: ≤0.5; Mn: ≤0.30; Si: ≤0.30;

[0136] High-temperature mechanical properties: Tensile strength: At 900°C, the tensile strength is not less than 640 MPa; Elongation: not less than 8%; Creep strength: At 900°C, the tensile stress is not less than 270 MPa, and the time is not less than 100 h;

[0137] Low-magnification grain size: At the exhaust side of the blade body 1, it is not greater than grade 5 (2.82 mm), and in other parts, it is not greater than grade 7 (5.64 mm).

[0138] The structure of the turbine moving blade of the present invention is a shrouded moving blade, the maximum length of the blade is 410 mm, the whole blade is cast without machining allowance, the length of the blade body reaches 330 mm, accounting for 80% of the total blade length, and the blade body has a large twist, a large change in the maximum thickness of the blade body and the thickness of the steam outlet edge, and a large shrinkage of the spatial dimensions.

[0139] The above are only the preferred embodiments of the present invention and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments by using the above-disclosed technical content within the scope of the technical solution of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention and is based on the technical essence of the present invention, any simple modification, equivalent replacement, and improvement made to the above embodiments still fall within the protection scope of the technical solution of the present invention.

Claims

1. An advanced solidification forming method for high-power gas turbine blades, characterized in that: The method comprises the following steps: Step 1: Moulding: Step 1: On the wax pressing machine, select medium-temperature wax material, press it according to the mold of the required gas turbine rotor blade, and keep the pressure in the mold after wax injection. The wax mold is taken out after keeping the pressure for 50-60 seconds; Step 1 and 2: Correct the wax model to make it flawless; Step 13: Assemble the wax mold and the pouring and riser; Step 2: Shell making: Step 21: On the outer surface of the wax mold obtained in step 1, a surface coating with silica sol as a binder is used to make a mold shell; Step 22: The surface layer of the shell is made of a surface coating with a surface refiner, the surface powder of the second layer is made of corundum sand, and the third layer and the back layer shell are made of mullite powder to form a high-strength refractory shell; Step 2 and 3: Air-dry the shell until it reaches the specified strength, and then use steam to dewax. The dewaxing temperature is 140-160°C, the pressure head is 0.4-0.6MPa, and the pressure holding time is 10-15 minutes; Step 3: Vacuum melting and pouring: Step 31: Wrap the outer shell of step 2 with thermal insulation felt; Step 32: calcining the shell at a temperature of 850-950°C; Step 33: using a vacuum induction casting furnace to cast the gas turbine rotor blades, the metal raw materials used are subjected to vacuum smelting and vacuum pouring to obtain the required castings; Step 3 and 4: After the pouring is completed, the obtained casting is kept in a vacuum state for 10 to 15 minutes, then taken out and placed in an insulated box for cooling; Step 4: Vacuum heat treatment: Step 41: performing a solution treatment on the casting obtained in step 3; The solution treatment process is as follows: the solution temperature is 1150-1170°C, then kept at this temperature for 3-3.5 hours, and then cooled by blowing argon gas; Step 42: After the solution treatment is completed, the casting is subjected to the first aging treatment. The temperature of the first aging treatment is 1050-1070°C and the holding time is 4-4.5 hours; Step 43: After aging treatment, cooling with argon gas is performed; Step 44: Perform a second aging treatment on the casting, the temperature of the second aging treatment is 840-860°C, the insulation time is 16-17 hours, and then argon blowing cooling is performed to obtain the gas turbine rotor blade.

2. The advanced solidification forming method for high-power gas turbine rotor blades according to claim 1, characterized in that: The vacuum smelting in step 33 comprises the following steps: Step 331: Vacuuming: Start the vacuum system to evacuate the vacuum furnace, and after the air in the furnace is extracted, a vacuum state is achieved; Step 332: Loading: First, the metal raw materials for manufacturing the moving blades are loaded into the crucible of the vacuum induction casting furnace; Step 333: Power on and melt: In the vacuum state, metal raw materials are added into the crucible. Through the principle of electromagnetic induction, eddy currents are generated in the metal raw materials, causing the metal raw materials to heat up and melt rapidly. During the melting process, the power supply should be controlled according to the melting point and characteristics of the metal. Step 334: Refining: Remove oxygen from the molten metal and use the vacuum environment to allow hydrogen gas to escape.

3. The advanced solidification forming method for high-power gas turbine rotor blades according to claim 2, characterized in that: The vacuum pouring in step 33 comprises the following steps: Step 331: Preheating the mold shell: Heat the shell to a temperature of 850-950°C so that the molten metal can better fill the complex shape of the shell; Step 332: Transfer and positioning in the furnace: The metal is melted in the crucible without moving. When pouring, the crucible is turned over and the casting is performed. The mold shell is moved and connected with the crucible gate to ensure successful casting and accurate connection between the pouring gate and the gate of the mold shell. Step 333: Start pouring: When the docking is completed, tilt the crucible for pouring, and quickly pour the molten metal into the shell. The pouring speed should be controlled according to the size and shape of the shell and the characteristics of the molten metal. Step 334: Processing after pouring: When the molten metal is completely injected into the mold shell, keep it in vacuum for 10-15 minutes, take the casting together with the mold shell out of the furnace, put it into the insulation box after taking it out, and the unpacking time is ≥5h for subsequent cleaning and processing.

4. The advanced solidification forming method for high-power gas turbine rotor blades according to claim 1, characterized in that: The solution treatment in step 4 comprises the following steps: Step 4: Heating: placing the blade casting into a vacuum heat treatment furnace to perform heat treatment on it; Step 412: Keep warm: After the blade casting reaches the solution temperature, it needs to be kept warm for 2-6 hours; Step 413: Cooling: The furnace is cooled by flushing argon gas.

5. The advanced solidification forming method for high-power gas turbine rotor blades according to claim 2 or 3, characterized in that: The smelting process of the vacuum induction casting furnace in step 33 is: The vacuum furnace is charged and powered on. After the melting and refining periods, the mold is loaded into the shell. The mold is evacuated and poured under a vacuum degree of no more than 1Pa. The mold is taken out and placed in an insulation box.

6. The advanced solidification forming method for high-power gas turbine rotor blades according to claim 5, characterized in that: In the step three, the temperature of vacuum melting and pouring in the vacuum induction casting furnace is 1470-1520° C., and the speed of vacuum pouring is 3 to 8 seconds per set.

7. The advanced solidification forming method for high-power gas turbine rotor blades according to claim 1, characterized in that: The temperature of the medium-temperature wax material in the step 1 is 70-100°C.

8. The advanced solidification forming method for high-power gas turbine rotor blades according to claim 1, characterized in that: The process of step 1 and 2: correcting the wax model to make it defect-free comprises the following steps: Step 121: Surface repair: For pits or pores, use repair wax to heat and melt to fill them. For scratches, use soft cloth or fine sandpaper to gently wipe and smooth them. Step 122: Remove flash and burrs: Trim off the excess wax on the edge of the wax model, keeping close to the wax model body during the operation to ensure that the trimmed edge is flat and smooth; Steps 1, 2, and 3: Size and shape correction: Apply a layer of melted wax evenly on the surface to increase the thickness and reach the standard size.

9. The advanced solidification forming method for high-power gas turbine rotor blades according to claim 1, characterized in that: In the steps 2 and 3, the shell reaches a specified strength, and the strength required for the shell during high-temperature roasting and pouring of molten metal is the high-temperature strength.

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