High-temperature alloy K403 casting for isothermal forging die and production process of high-temperature alloy K403 casting

Abstract

The invention discloses a high-temperature alloy K403 casting for an isothermal forging die and a production process of the high-temperature alloy K403 casting, and belongs to the technical field of isothermal forging dies, and the high-temperature alloy K403 casting sequentially comprises a rigid supporting layer of 10-15 mm, a backing layer of 5-8 mm, a buffer layer of 1-3 mm and an anti-erosion layer of 2-4 mm. According to the invention, ZrO2 strengthens the strength and oxidation resistance of a matrix, and forms functional complementation with corrosion resistance and thermal fatigue resistance protection of a multi-layer structure; ZrO2 particles in the matrix improve the bearing capacity of the material, so that coating failure caused by insufficient strength is avoided; the surface multi-layer structure ensures that a protection system is stable through a physical barrier and stress regulation and control, the oxidation resistance, the high-temperature tensile strength, the corrosion resistance and the thermal fatigue resistance of a K403 casting are synergistically improved through compounding of the two, and the performance defects of a traditional K403 alloy applied to an isothermal forging die are systematically overcome.

Description

Technical Field

[0001] The present invention relates to the technical field of isothermal forging dies, and in particular to a high-temperature alloy K403 casting for an isothermal forging die and a production process thereof. Background Art

[0002] High-temperature alloys are ideal materials for isothermal forging dies due to their excellent high-temperature strength, oxidation resistance, and thermal fatigue resistance. K403, a nickel-based precipitation-hardening equiaxed crystal casting high-temperature alloy, has high strength below 1000°C and good casting performance. It is widely used in the manufacture of high-temperature components such as aircraft engines.

[0003] However, this alloy exhibits significant performance shortcomings in practical applications: its matrix exhibits insufficient surface protection when subjected to high-temperature oxidation and molten salt corrosion, making it susceptible to oxide film flaking and intergranular corrosion, leading to rapid mold surface failure. While existing technologies employ the addition of ceramic coatings for surface protection, the thermal expansion coefficients of these coatings and the alloy substrate are poorly matched, making them susceptible to shedding and cracking under cyclic thermal stress. This results in the failure of the protective system and limits the long-term reliable application of K403 alloy in isothermal forging dies.

[0004] Based on this, the present invention designs a high-temperature alloy K403 casting for isothermal forging dies and a production process thereof to solve the above problems. Summary of the Invention

[0005] In view of the above-mentioned shortcomings of the prior art, the present invention provides a high-temperature alloy K403 casting for an isothermal forging die and a production process thereof.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0007] High-temperature alloy K403 castings for isothermal forging dies, which sequentially include a 10-15mm rigid support layer, a 5-8mm backing layer, a 1-3mm buffer layer, and a 2-4mm anti-corrosion layer;

[0008] The rigid support layer comprises the following components by mass percentage:

[0009] Al: 5%-6%, Ti: 4%-5%, Co: 10%-12%, W: 4%-6%, C: 0.12%-0.18%, Re: 0.8%-1.2%, ZrO2: 0.5%-0.8%, and the balance is Ni.

[0010] The production process of the high-temperature alloy K403 casting for the isothermal forging die comprises the following steps:

[0011] S1 premix:

[0012] Add Ni block, Cr powder, Co ingot and W ingot into the crucible of vacuum induction furnace, stir and heat until completely melted to form Ni-Cr-Co-W based melt;

[0013] Al blocks and Ti blocks are sequentially added to the Ni-Cr-Co-W based melt. After heating, graphite-Al coated powder is added in batches while stirring.

[0014] Add Re-Ni premixed particles and ZrO2-Ni prealloyed powder and keep warm;

[0015] Ultrasonic vibration treatment to obtain a melt;

[0016] S2 casting:

[0017] The Al2O3 ceramic particles are evenly sprayed onto the melt surface through an inert gas blowing device;

[0018] After the melt is filtered, it is injected into a preheated steel mold and solidified to obtain a rigid support layer;

[0019] S3 anti-corrosion layer preparation:

[0020] Dry-mix YSZ ceramic powder and dispersant, add silica sol binder, and stir while adding to obtain anti-corrosion slurry;

[0021] S4 thermal stress buffer layer preparation:

[0022] Aluminum silicate fibers are dispersed and disentangled in a high-speed shearing machine, and aluminum sol binder and refractory clay are added, and stirred at a low speed to obtain a buffer layer slurry;

[0023] S5 backing layer preparation:

[0024] ZrO2 powder and calcium aluminate cement are mixed with water to form a paste to obtain a backing layer paste;

[0025] S6 compounding:

[0026] The backing layer paste is coated on the inner wall of the rigid support layer, and after solidification, the buffer layer slurry is coated by brushing, and mixed sand is sprinkled after coating, and the mixed sand is embedded in the buffer layer; after solidification, the anti-corrosion slurry is coated by dip coating, and after solidification, YSZ sand is sprinkled in an electrostatic field to obtain a high-temperature alloy K403 casting for an isothermal forging die.

[0027] Furthermore, S1 specifically comprises: adding Ni block, Cr powder, Co ingot, and W ingot into a crucible of a vacuum induction furnace, stirring at 200-300 rpm, and heating to 1450-1500° C. to completely melt to form a Ni-Cr-Co-W based melt;

[0028] Add Al blocks to the Ni-Cr-Co-W based melt, then add Ti blocks 5-10 minutes later. After heating to 1680-1720°C, add graphite-Al coated powder in three batches while stirring at 200-300 rpm.

[0029] Add Re-Ni premixed particles and ZrO2-Ni prealloyed powder and keep warm for 10-15 minutes;

[0030] Ultrasonic vibration treatment with a power of 1-2 kW is used for 8-12 minutes to break up the ZrO2 agglomerates and obtain a melt.

[0031] Furthermore, S2 is specifically as follows: through a screw feeder and an inert gas delivery system, 50-100 μm Al2O3 ceramic particles are evenly sprayed onto the melt surface in a vacuum induction furnace through a nozzle under the propulsion of argon gas, with a spraying pressure of 0.2-0.3 MPa;

[0032] After being filtered through a 180-200 mesh zirconia ceramic filter, the melt is injected into a steel mold preheated to 300-400°C at a linear speed of 30-40 mm / s to solidify to obtain a rigid support layer with a thickness of 10-15 mm.

[0033] Furthermore, S3 is specifically as follows: dry-mixing YSZ ceramic powder with a particle size of ≤10 μm and sodium hexametaphosphate as a dispersant, adding a silica sol binder with a modulus of 2.8-3.2, and stirring while adding to obtain an anti-corrosion slurry;

[0034] The mass ratio of the YSZ ceramic powder, silica sol binder and dispersant is 70-80:15-20:0.5-1.

[0035] Furthermore, S4 is specifically as follows: dispersing and disentangling aluminum silicate fibers with a diameter of 2-5 μm and a length of 50-100 μm in a high-speed shearing machine, adding an aluminum sol binder with a pH value of 3-4 and an Al2O3 content of ≥20% and refractory clay with a particle size of ≤5 μm, and stirring at a low speed to obtain a buffer layer slurry;

[0036] The mass ratio of the aluminum silicate fiber, the aluminum sol binder and the refractory clay is 60-71:28-35:8-10.

[0037] Furthermore, S5 specifically comprises: ZrO2 powder and calcium aluminate cement, which are mixed with water to form a paste to obtain a backing layer paste; the mass ratio of the ZrO2 powder to the calcium aluminate cement is 32-45:61-73.

[0038] Furthermore, S6 is specifically as follows: a backing layer paste with a thickness of 5-8 mm is coated on the inner wall of the rigid support layer, and after curing, a buffer layer slurry of 1-3 mm is coated by brushing, and mixed sand is sprinkled after coating, and the mixed sand is embedded in the buffer layer to form a mechanical bite structure; after curing, a 2-4 mm anti-corrosion slurry is coated by dip coating, and after curing, 20-40 μm YSZ sand is sprinkled in an electrostatic field with a voltage of 5-10 kV. The YSZ sand is vertically adsorbed on the surface of the anti-corrosion layer under the action of the electric field to obtain a high-temperature alloy K403 casting for isothermal forging molds. The mixed sand is 40-60 μm quartz sand and 60-80 μm corundum sand in a mass ratio of 3-5:2-6.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] 1. The present invention adds ZrO2 to the rigid support layer and utilizes its dispersion strengthening effect to refine the alloy grains and stabilize the grain boundary structure, thereby significantly improving the high-temperature tensile strength of K403 castings below 1000°C, and having better load-bearing capacity than traditional K403 alloy; at the same time, the composite oxide film formed by ZrO2 and the matrix can block the diffusion of oxygen and corrosive media, greatly enhancing the antioxidant performance, and improving the problem of insufficient heat resistance of the original alloy from the intrinsic level of the material.

[0041] 2. A mixed sand mechanical interlocking structure is provided between the anti-erosion layer and the buffer layer of the present invention, and a physical interlock is formed by embedding quartz sand and corundum sand, which significantly improves the coating interface bonding strength, avoids the problem of coating shedding due to thermal expansion difference, ensures the long-term stable adhesion of the anti-erosion layer in a high-temperature environment, and effectively protects the mold surface without the need for additional protective coating. The YSZ sand electrostatically adsorbed on the outer surface of the anti-erosion layer uses its high chemical stability to construct a dense corrosion-resistant barrier, directly blocking the contact of media such as molten salt and oxygen with the substrate, significantly improving the high-temperature corrosion resistance and solving the key problem of the traditional K403 alloy surface being easily corroded. The aluminum silicate fiber composite system of the buffer layer absorbs thermal cycling stress through elastic deformation of the fiber, reduces the thermal expansion mismatch stress between the substrate and the coating, greatly improves the thermal fatigue resistance, and effectively extends the service life of the mold under repeated high-temperature loads.

[0042] 3. The ZrO2 in the present invention strengthens the strength and oxidation resistance of the matrix, and forms a functional complement with the corrosion resistance and thermal fatigue resistance of the multi-layer structure: the ZrO2 particles inside the matrix improve the material's bearing capacity, avoiding coating failure due to insufficient strength; the surface multi-layer structure ensures the stability of the protection system through physical barriers and stress regulation. The combination of the two enables the K403 casting's oxidation resistance, high-temperature tensile strength, corrosion resistance and thermal fatigue resistance to be synergistically improved, systematically solving the performance defects of traditional K403 alloy in isothermal forging die applications. DETAILED DESCRIPTION

[0043] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0044] Example 1: This example provides a high-temperature alloy K403 casting for an isothermal forging die, which includes a 15 mm rigid support layer, an 8 mm backing layer, a 3 mm buffer layer, and a 4 mm anti-erosion layer in sequence;

[0045] The rigid support layer comprises the following components by mass percentage:

[0046] Al: 6%, Ti: 5%, Co: 12%, W: 6%, C: 0.18%, Re: 1.2%, ZrO2: 0.8%, and the balance is Ni.

[0047] The production process of the high-temperature alloy K403 casting for the isothermal forging die comprises the following steps:

[0048] S1 premix:

[0049] Ni blocks, Cr powder, Co ingots, and W ingots were added to a crucible of a vacuum induction furnace, stirred at 300 rpm, and heated to 1500°C for complete melting to form a Ni-Cr-Co-W based melt.

[0050] Al blocks were added to the Ni-Cr-Co-W based melt, followed by Ti blocks 10 minutes later. After heating to 1720°C, graphite-Al coated powder was added in three batches (5 minutes between each addition) while stirring at 300 rpm.

[0051] Add Re-Ni premixed particles and ZrO2-Ni prealloyed powder and keep warm for 15 minutes;

[0052] Ultrasonic vibration treatment with a power of 2 kW was used for 12 min to break up ZrO2 agglomerates and obtain a melt;

[0053] S2 casting:

[0054] Through a screw feeder and an inert gas delivery system, 100 μm Al2O3 ceramic particles are evenly sprayed onto the melt surface in a vacuum induction furnace through a nozzle under the push of argon gas, with a spraying pressure of 0.3 MPa.

[0055] After being filtered through a 200-mesh zirconia ceramic filter, the melt was injected into a steel mold preheated to 400°C at a linear speed of 40 mm / s to solidify into a rigid support layer with a thickness of 15 mm.

[0056] S3 anti-corrosion layer preparation:

[0057] YSZ ceramic powder (Y2O3 stability 8%, particle size ≤10μm);

[0058] Silica sol binder (SiO2 content 30%, modulus 3.2);

[0059] Dispersant (sodium hexametaphosphate);

[0060] The mass ratio of the YSZ ceramic powder, silica sol binder and dispersant is 80:20:1;

[0061] YSZ ceramic powder and dispersant were dry-mixed (three-dimensional mixer, speed 50 rpm, time 30 min), and silica sol binder was added while stirring (paddle stirrer, speed 150 rpm, time 20 min) to obtain an anti-corrosion slurry;

[0062] S4 thermal stress buffer layer preparation:

[0063] Aluminum silicate fibers (5 μm in diameter, 100 μm in length);

[0064] Aluminum sol binder (Al2O3 content 20%, pH 4);

[0065] Refractory clay (particle size ≤ 5 μm);

[0066] The mass ratio of the aluminum silicate fiber, aluminum sol binder and refractory clay is 71:35:10;

[0067] First, the aluminum silicate fibers were dispersed and disentangled in a high-speed shearing machine (speed 5000 rpm, time 10 min), and then aluminum sol binder and refractory clay were added and stirred at low speed (200 rpm, time 15 min) to obtain a buffer layer slurry;

[0068] S5 backing layer preparation:

[0069] ZrO2 powder and calcium aluminate cement are mixed with water to form a paste to obtain a backing layer paste; the mass ratio of the ZrO2 powder to the calcium aluminate cement is 45:73;

[0070] S6 compounding:

[0071] An 8mm thick backing layer paste is coated on the inner wall of the rigid support layer. After curing, a 3mm thick buffer layer slurry is applied by brushing. After coating, mixed sand (60μm quartz sand and 80μm corundum sand in a mass ratio of 5:6) is sprinkled on the buffer layer to form a mechanical bite structure. After curing, a 4mm thick anti-corrosion slurry is coated by dip coating. After curing, 40μm YSZ sand is sprinkled in an electrostatic field with a voltage of 10kV. The YSZ sand is vertically adsorbed on the surface of the anti-corrosion layer under the action of the electric field to obtain a high-temperature alloy K403 casting for an isothermal forging die.

[0072] Example 2: This example provides a high-temperature alloy K403 casting for an isothermal forging die, which includes a 10 mm rigid support layer, a 5 mm backing layer, a 1 mm buffer layer, and a 2 mm anti-erosion layer in sequence;

[0073] The rigid support layer comprises the following components by mass percentage:

[0074] Al: 5%, Ti: 4%, Co: 10%, W: 4%, C: 0.12%, Re: 0.8%, ZrO2: 0.5%, and the balance is Ni.

[0075] The production process of the high-temperature alloy K403 casting for the isothermal forging die comprises the following steps:

[0076] S1 premix:

[0077] Ni blocks, Cr powder, Co ingots, and W ingots were added to a crucible in a vacuum induction furnace, stirred at 200 rpm, and heated to 1450°C for complete melting to form a Ni-Cr-Co-W based melt.

[0078] Al blocks were added to the Ni-Cr-Co-W based melt, followed by Ti blocks after 5 minutes. After heating to 1680°C, graphite-Al coated powder was added in three batches (5 minutes between each addition) while stirring at 200 rpm.

[0079] Add Re-Ni premixed particles and ZrO2-Ni prealloyed powder and keep warm for 10 minutes;

[0080] Ultrasonic vibration treatment with a power of 1 kW was used for 8 min to break up ZrO2 agglomerates and obtain a melt;

[0081] S2 casting:

[0082] Through a screw feeder and an inert gas delivery system, 50μm Al2O3 ceramic particles are evenly sprayed onto the melt surface in a vacuum induction furnace through a nozzle under the push of argon gas, with a spraying pressure of 0.2MPa.

[0083] After being filtered through a 180-mesh zirconia ceramic filter, the melt was injected into a steel mold preheated to 300°C at a linear speed of 30 mm / s to solidify into a rigid support layer with a thickness of 10 mm.

[0084] S3 anti-corrosion layer preparation:

[0085] YSZ ceramic powder (Y2O3 stability 8%, particle size ≤10μm);

[0086] Silica sol binder (SiO2 content 30%, modulus 2.8);

[0087] Dispersant (sodium hexametaphosphate);

[0088] The mass ratio of the YSZ ceramic powder, silica sol binder and dispersant is 70:15:0.5;

[0089] YSZ ceramic powder and dispersant were dry-mixed (three-dimensional mixer, speed 50 rpm, time 30 min), and silica sol binder was added while stirring (paddle stirrer, speed 150 rpm, time 20 min) to obtain an anti-corrosion slurry;

[0090] S4 thermal stress buffer layer preparation:

[0091] Aluminum silicate fibers (2 μm in diameter, 50 μm in length);

[0092] Aluminum sol binder (Al2O3 content 20%, pH 3);

[0093] Refractory clay (particle size ≤ 5 μm);

[0094] The mass ratio of the aluminum silicate fiber, aluminum sol binder and refractory clay is 60:28:8;

[0095] First, the aluminum silicate fibers were dispersed and disentangled in a high-speed shearing machine (speed 5000 rpm, time 10 min), and then aluminum sol binder and refractory clay were added and stirred at low speed (200 rpm, time 15 min) to obtain a buffer layer slurry;

[0096] S5 backing layer preparation:

[0097] ZrO2 powder and calcium aluminate cement are added with water to form a paste to obtain a backing layer paste; the mass ratio of the ZrO2 powder to the calcium aluminate cement is 32:61;

[0098] S6 compounding:

[0099] A 5mm thick backing layer paste is coated on the inner wall of the rigid support layer. After curing, a 1mm thick buffer layer slurry is applied by brushing. After coating, mixed sand (40μm quartz sand and 60μm corundum sand in a mass ratio of 3:2) is sprinkled. The mixed sand is embedded in the buffer layer to form a mechanical bite structure. After curing, a 2mm thick anti-corrosion slurry is coated by dip coating. After curing, 20μm YSZ sand is sprinkled in an electrostatic field with a voltage of 5kV. The YSZ sand is vertically adsorbed on the surface of the anti-corrosion layer under the action of the electric field to obtain a high-temperature alloy K403 casting for an isothermal forging die.

[0100] Example 3: This example provides a high-temperature alloy K403 casting for an isothermal forging die, which sequentially comprises a 12 mm rigid support layer, a 7 mm backing layer, a 2 mm buffer layer, and a 3 mm anti-erosion layer;

[0101] The rigid support layer comprises the following components by mass percentage:

[0102] Al: 5.6%, Ti: 4.8%, Co: 10.3%, W: 4.9%, C: 0.16%, Re: 1.1%, ZrO2: 0.7%, and the balance is Ni.

[0103] The production process of the high-temperature alloy K403 casting for the isothermal forging die comprises the following steps:

[0104] S1 premix:

[0105] Ni blocks, Cr powder, Co ingots, and W ingots were added to a crucible in a vacuum induction furnace, stirred at 230 rpm, and heated to 1480°C for complete melting to form a Ni-Cr-Co-W based melt.

[0106] Al blocks were added to the Ni-Cr-Co-W based melt, followed by Ti blocks 8 minutes later. After heating to 1695°C, graphite-Al coated powder was added in three batches (5 minutes between each addition) while stirring at 280 rpm.

[0107] Add Re-Ni premixed particles and ZrO2-Ni prealloyed powder and keep warm for 14 minutes;

[0108] Ultrasonic vibration treatment with a power of 1 kW was used for 11 min to break up ZrO2 agglomerates and obtain a melt;

[0109] S2 casting:

[0110] Through a screw feeder and an inert gas delivery system, 80μm Al2O3 ceramic particles are evenly sprayed onto the melt surface in a vacuum induction furnace through a nozzle under the push of argon gas, with a spraying pressure of 0.25MPa.

[0111] After being filtered through a 180-mesh zirconia ceramic filter, the melt was injected into a steel mold preheated to 360°C at a linear speed of 34 mm / s to solidify into a rigid support layer with a thickness of 12 mm.

[0112] S3 anti-corrosion layer preparation:

[0113] YSZ ceramic powder (Y2O3 stability 8%, particle size ≤10μm);

[0114] Silica sol binder (SiO2 content 30%, modulus 3.1);

[0115] Dispersant (sodium hexametaphosphate);

[0116] The mass ratio of the YSZ ceramic powder, silica sol binder and dispersant is 75:16:0.8;

[0117] YSZ ceramic powder and dispersant were dry-mixed (three-dimensional mixer, speed 50 rpm, time 30 min), and silica sol binder was added while stirring (paddle stirrer, speed 150 rpm, time 20 min) to obtain an anti-corrosion slurry;

[0118] S4 thermal stress buffer layer preparation:

[0119] Aluminum silicate fibers (5 μm in diameter, 80 μm in length);

[0120] Aluminum sol binder (Al2O3 content 20%, pH 4);

[0121] Refractory clay (particle size ≤ 5 μm);

[0122] The mass ratio of the aluminum silicate fiber, aluminum sol binder and refractory clay is 70:31:9;

[0123] First, the aluminum silicate fibers were dispersed and disentangled in a high-speed shearing machine (speed 5000 rpm, time 10 min), and then aluminum sol binder and refractory clay were added and stirred at low speed (200 rpm, time 15 min) to obtain a buffer layer slurry;

[0124] S5 backing layer preparation:

[0125] ZrO2 powder and calcium aluminate cement are mixed with water to form a paste to obtain a backing layer paste; the mass ratio of the ZrO2 powder to the calcium aluminate cement is 41:72;

[0126] S6 compounding:

[0127] A 7mm thick backing layer paste is coated on the inner wall of the rigid support layer. After curing, a 2mm thick buffer layer slurry is applied by brushing. After coating, mixed sand (50μm quartz sand and 70μm corundum sand in a mass ratio of 4:3) is sprinkled. The mixed sand is embedded in the buffer layer to form a mechanical bite structure. After curing, a 3mm thick anti-corrosion slurry is coated by dip coating. After curing, 30μm YSZ sand is sprinkled in an electrostatic field with a voltage of 8kV. The YSZ sand is vertically adsorbed on the surface of the anti-corrosion layer under the action of the electric field to obtain a high-temperature alloy K403 casting for isothermal forging molds.

[0128] Comparative Example 1: This comparative example differs from Example 3 in that no ZrO2-Ni pre-alloyed powder is added.

[0129] Comparative Example 2: The difference between this comparative example and Example 3 lies in the S6 compounding: a backing layer paste with a thickness of 7 mm is coated on the inner wall of the rigid support layer, a buffer layer slurry with a thickness of 2 mm is coated by brushing after solidification, and a corrosion-resistant slurry with a thickness of 3 mm is coated by dipping after solidification to obtain a high-temperature alloy K403 casting for isothermal forging dies.

[0130] Comparative Example 3: The difference between this comparative example and Example 3 is that no ZrO2-Ni pre-alloyed powder is added, and no mixed sand is spread between the anti-erosion layer and the buffer layer, and no YSZ sand is spread outside the anti-erosion layer.

[0131] Experimental example: 1. The high-temperature corrosion rate Vp (700°C, Na2SO4-K2SO4 molten salt, 200h, static molten salt corrosion test) was tested according to the standard of GB / T 42912-2023.

[0132] 2. Test the oxidation resistance according to GB / T 13303-1991 (1000℃, 100h, constant temperature oxidation test) and calculate the oxidation weight gain Mo (mg / cm 2 ).

[0133] 3. Pass the GB / T 228.2-2015 standard test of high temperature tensile strength P (1000℃, strain rate 1×10 -4 / s, high temperature tensile test).

[0134] 4. Pass the GB / T 15248-2008 standard to test thermal fatigue resistance (room temperature to 1000℃, 1000 cycles, cyclic heating and cooling test).

[0135] The result is as follows:

[0136]

[0137]

[0138] It can be seen from the above table that ZrO2 can effectively improve the oxidation resistance and high-temperature tensile strength of high-temperature alloy K403 castings; the mixed sand between the anti-erosion layer and the buffer layer and the YSZ sand outside the anti-erosion layer can significantly improve the high-temperature corrosion resistance and thermal fatigue resistance of high-temperature alloy K403 castings; the combination of the two can produce a synergistic effect on the oxidation resistance, high-temperature tensile strength, high-temperature corrosion resistance and thermal fatigue resistance of high-temperature alloy K403 castings.

[0139] Here’s how it works:

[0140] In a high-temperature oxidizing environment, a dense Zr-containing oxide film is preferentially formed on the surface of ZrO2 particles. This oxide film and the Ni-Al spinel oxide layer generated in the matrix form a "composite protective barrier" that can effectively block the oxidation of O 2- The bidirectional diffusion of metal ions can inhibit the oxidation weight loss and internal oxidation of the matrix alloy, thereby improving the antioxidant performance.

[0141] ZrO2, as a high-temperature resistant ceramic phase, is dispersed in the Ni-based alloy matrix. It inhibits the abnormal growth of grains at high temperatures through the "grain boundary pinning effect", refines the matrix structure and stabilizes the grain boundary structure, thereby improving the alloy's high-temperature deformation resistance (enhanced high-temperature tensile strength).

[0142] The mixed sand (quartz sand and corundum sand) spread between the anti-erosion layer and the buffer layer becomes embedded in the buffer layer slurry during the curing process, forming a "mechanical interlocking structure." This structure significantly enhances the interfacial bonding strength between the two layers through physical meshing, preventing interfacial debonding caused by the difference in thermal expansion coefficient between the coating and the substrate. This ensures the integrity of the coating system under high-temperature cyclic loading, thereby enhancing thermal fatigue resistance.

[0143] The outer surface of the anti-corrosion layer is adsorbed by YSZ sand (Y2O3 stabilized ZrO2) through an electrostatic field, forming a high-density "micro-peak structure" on the coating surface. On the one hand, this structure prevents corrosive media such as molten salts and oxygen from penetrating into the substrate through its physical barrier effect. On the other hand, it utilizes the high chemical stability of YSZ itself (such as resistance to sulfate molten salt corrosion) to form a stable inert protective layer in high-temperature corrosive environments, thereby reducing the corrosion rate of the substrate.

[0144] The grain refinement and grain boundary strengthening of ZrO2 in the matrix improve the internal bearing capacity, and the surface YSZ sand coating prevents external oxidation corrosion. The combination of the two enables the alloy to maintain high strength at high temperatures while avoiding surface oxidation failure. The mechanical bite structure ensures that the coating does not fall off, making the corrosion-resistant layer formed by YSZ sand effective for a long time; the buffer layer reduces thermal stress and prevents the coating from cracking due to repeated hot and cold cycles, ultimately achieving a simultaneous improvement in corrosion resistance and thermal fatigue resistance at high temperatures.

[0145] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. High temperature alloy K403 casting for isothermal forging die, characterized by: It consists of a 10-15mm rigid support layer, a 5-8mm backing layer, a 1-3mm buffer layer and a 2-4mm anti-erosion layer. The rigid support layer comprises the following components by mass percentage: Al: 5%-6%, Ti: 4%-5%, Co: 10%-12%, W: 4%-6%, C: 0.12%-0.18%, Re: 0.8%-1.2%, ZrO2: 0.5%-0.8%, and the balance is Ni.

2. The production process of high-temperature alloy K403 castings for isothermal forging dies according to claim 1, characterized in that: The following steps are involved: S1 premix: Add Ni block, Cr powder, Co ingot and W ingot into the crucible of vacuum induction furnace, stir and heat until completely melted to form Ni-Cr-Co-W based melt; Al blocks and Ti blocks are sequentially added to the Ni-Cr-Co-W based melt. After heating, graphite-Al coated powder is added in batches while stirring. Add Re-Ni premixed particles and ZrO2-Ni prealloyed powder and keep warm; Ultrasonic vibration treatment to obtain a melt; S2 casting: The Al2O3 ceramic particles are evenly sprayed onto the melt surface through an inert gas blowing device; After the melt is filtered, it is injected into a preheated steel mold and solidified to obtain a rigid support layer; S3 anti-corrosion layer preparation: Dry-mix YSZ ceramic powder and dispersant, add silica sol binder, and stir while adding to obtain anti-corrosion slurry; S4 thermal stress buffer layer preparation: Aluminum silicate fibers are dispersed and disentangled in a high-speed shearing machine, and aluminum sol binder and refractory clay are added, and stirred at a low speed to obtain a buffer layer slurry; S5 backing layer preparation: ZrO2 powder and calcium aluminate cement are mixed with water to form a paste to obtain a backing layer paste; S6 compounding: The backing layer paste is coated on the inner wall of the rigid support layer, and after curing, the buffer layer slurry is coated by brushing, and mixed sand is sprinkled after coating, and the mixed sand is embedded in the buffer layer; after curing, the anti-corrosion slurry is coated by dip coating, and after curing, YSZ sand is sprinkled in an electrostatic field to obtain a high-temperature alloy K403 casting for an isothermal forging die.

3. The production process of high-temperature alloy K403 castings for isothermal forging dies according to claim 2, characterized in that: S1 specifically comprises: adding Ni block, Cr powder, Co ingot, and W ingot into a crucible of a vacuum induction furnace, stirring at 200-300 rpm, and heating to 1450-1500° C. to completely melt to form a Ni-Cr-Co-W based melt; Add Al blocks to the Ni-Cr-Co-W based melt, then add Ti blocks 5-10 minutes later. After heating to 1680-1720°C, add graphite-Al coated powder in three batches while stirring at 200-300 rpm. Add Re-Ni premixed particles and ZrO2-Ni prealloyed powder and keep warm for 10-15 minutes; Ultrasonic vibration treatment with a power of 1-2 kW is used for 8-12 minutes to break up the ZrO2 agglomerates and obtain a melt.

4. The production process of high-temperature alloy K403 castings for isothermal forging dies according to claim 2, characterized in that: S2 is specifically as follows: through a screw feeder and an inert gas conveying system, 50-100μm Al2O3 ceramic particles are evenly sprayed into the melt surface in a vacuum induction furnace through a nozzle under the promotion of argon gas, with a spraying pressure of 0.2-0.3MPa; After being filtered through a 180-200 mesh zirconia ceramic filter, the melt is injected into a steel mold preheated to 300-400°C at a linear speed of 30-40 mm / s to solidify to obtain a rigid support layer with a thickness of 10-15 mm.

5. The production process of high-temperature alloy K403 castings for isothermal forging dies according to claim 2, characterized in that: S3 is specifically as follows: dry-mixing YSZ ceramic powder with a particle size of ≤10 μm and sodium hexametaphosphate as a dispersant, adding a silica sol binder with a modulus of 2.8-3.2, and stirring while adding to obtain an anti-corrosion slurry; The mass ratio of the YSZ ceramic powder, silica sol binder and dispersant is 70-80:15-20:0.5-1.

6. The production process of high-temperature alloy K403 castings for isothermal forging dies according to claim 2, characterized in that: S4 specifically comprises: dispersing and disentangling aluminum silicate fibers with a diameter of 2-5 μm and a length of 50-100 μm in a high-speed shearing machine, adding an aluminum sol binder with a pH value of 3-4 and an Al2O3 content of ≥20% and refractory clay with a particle size of ≤5 μm, and stirring at a low speed to obtain a buffer layer slurry; The mass ratio of the aluminum silicate fiber, the aluminum sol binder and the refractory clay is 60-71:28-35:8-10.

7. The production process of high-temperature alloy K403 castings for isothermal forging dies according to claim 2, characterized in that: S5 specifically comprises: ZrO2 powder and calcium aluminate cement, which are mixed with water to form a paste to obtain a backing layer paste; the mass ratio of the ZrO2 powder to the calcium aluminate cement is 32-45:61-73.

8. The production process of high-temperature alloy K403 castings for isothermal forging dies according to claim 2, characterized in that: S6 is specifically as follows: a backing layer paste with a thickness of 5-8mm is coated on the inner wall of the rigid support layer, and a buffer layer slurry of 1-3mm is coated by brushing after curing, and mixed sand is sprinkled after coating, and the mixed sand is embedded in the buffer layer to form a mechanical bite structure; after curing, a 2-4mm anti-corrosion slurry is coated by dip coating, and after curing, 20-40μm YSZ sand is sprinkled in an electrostatic field with a voltage of 5-10kV. The YSZ sand is vertically adsorbed on the surface of the anti-corrosion layer under the action of the electric field to obtain a high-temperature alloy K403 casting for isothermal forging molds. The mixed sand is 40-60μm quartz sand and 60-80μm corundum sand in a mass ratio of 3-5:2-6.

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