High-temperature alloy low-segregation cast ingot and preparation method thereof

Abstract

The invention discloses a high-temperature alloy low-segregation cast ingot and a preparation method thereof, belongs to the technical field of difficult-to-deform high-temperature alloys, and solves the problems that the existing high-temperature alloy cast ingot is large in segregation degree and poor in uniformity. The preparation method comprises the following steps: smelting to obtain alloy liquid; the alloy liquid is poured in an ingot mold, pulse electromagnetism treatment is applied to the alloy liquid after pouring is started, pulse electromagnetism continues to act after the pouring process is completed, the pulse electromagnetism is turned off 60-100 s later, and a cast ingot is obtained; and the cast ingot is subjected to homogenization treatment, and the high-temperature alloy low-segregation cast ingot is obtained. The cast ingot prepared through the method is small in segregation, small in grain size and good in structure uniformity.

Description

Technical Field

[0001] The invention relates to the technical field of high-temperature alloys, and in particular to a high-temperature alloy low-segregation ingot and a preparation method thereof. Background Art

[0002] High-temperature alloy turbine disks are core components for manufacturing engines and gas turbines, and their metallurgical quality plays a decisive role in the reliability, safety life and performance of engines and gas turbines. Vacuum induction melting is the primary link in the smelting of deformed high-temperature alloys. If there is serious segregation of alloying elements such as Ti and Mo in vacuum induction ingots, the metallurgical quality and hot working plasticity of the ingots will be deteriorated, which will become the main obstacle to the preparation of high-alloy high-temperature alloy turbine disks.

[0003] The content of alloying elements such as Ti and Mo in high-temperature alloys is high. It is difficult to make the solute elements fully and evenly distributed during induction melting with existing technologies, resulting in serious ingot segregation, which brings difficulties to the subsequent smelting and hot processing of ingots. In addition, there are large columnar crystal structures in induction ingots, which further deteriorates the hot processing plasticity of ingots. Therefore, how to reduce the segregation of high-temperature alloys and improve the uniformity of high-temperature alloy ingots has become an urgent problem to be solved. Summary of the invention

[0004] In view of the above situation, the present invention aims to provide a high-temperature alloy low-segregation ingot and a preparation method thereof, so as to solve at least one of the following technical problems: the existing high-temperature alloy ingots have a large degree of segregation and poor uniformity.

[0005] The purpose of the present invention is mainly achieved through the following technical solutions:

[0006] The present invention provides a method for preparing a high-temperature alloy low-segregation ingot, comprising the following steps:

[0007] Step 1, smelting to obtain alloy liquid;

[0008] Step 2, pouring the alloy liquid into the ingot mold, applying pulse electromagnetic treatment to the alloy liquid after the pouring starts, continuing to apply the pulse electromagnetic after the pouring process is completed, and turning off the pulse electromagnetic after 60 to 100 seconds to obtain an ingot;

[0009] Step 3: homogenize the ingot to obtain a high-temperature alloy low-segregation ingot.

[0010] Furthermore, in step 2, the ingot mold is preheated in a heating furnace before pouring, and the preheating temperature is 400-600°C.

[0011] Furthermore, in step 2, the waveform of the pulse electromagnetic is a rectangular wave.

[0012] Furthermore, in step 2, the pulse electromagnetic current I and the ingot diameter d satisfy the following relationship: I=kd, the value range of k is 0.6-1, the unit of I is A, and the unit of d is mm.

[0013] Furthermore, in step 2, the ingot diameter d is 100-120 mm, and the pulse electromagnetic current I is 60-80 A; the ingot diameter d is 150-170 mm, and the pulse electromagnetic current I is 100-150 A; the ingot diameter d is 200-220 mm, and the pulse electromagnetic current I is 160-200 A.

[0014] Furthermore, in step 2, the current duty cycle of the pulse electromagnetic is 20% to 40%.

[0015] Furthermore, in step 3, the homogenization process includes the following steps:

[0016] S301, keeping the ingot at 650-750°C;

[0017] S302, heating to 1000-1020°C, keeping warm;

[0018] S303, heating to 1150-1170°C, keeping warm;

[0019] S304, heating to 1200-1220°C, keeping warm;

[0020] S305, cool down to 950-1050℃, keep warm; after taking out of the furnace, air cool to room temperature.

[0021] Furthermore, in step 3, the insulation time T1 of S301, the insulation time T2 of S302, the insulation time T3 of S303, and the insulation time T4 of S304 meet the following relationship: T1<T2, T3<T4.

[0022] Furthermore, in step 3, the heating rate V1 in S302, the heating rate V2 in S303, and the heating rate V3 in S304 satisfy the following relationship: V1>V2>V3.

[0023] The present invention also provides a high-temperature alloy low-segregation ingot, which is prepared by the above-mentioned preparation method.

[0024] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0025] a) In the preparation method of the high-temperature alloy low-segregation ingot of the present invention, pulse electromagnetic treatment is applied to the alloy liquid after the pouring begins. Under the action of the electromagnetic field, the solute fluidity at the front of the solidification interface increases, the solute elements can be fully mixed, the segregation degree of the ingot is significantly reduced, and the segregation behavior of the carbide is suppressed, and the uniformity of the alloy composition is improved; and during the pulse magnetic field treatment, convection movement occurs inside the alloy melt, the crystal nuclei on the mold wall fall off and become free, which increases the number of crystal nuclei in the alloy, promotes the formation of a large number of equiaxed crystals in the ingot, and the ingot structure is significantly refined, the columnar crystals are suppressed, and the segregation of alloy elements in the ingot is also reduced; the number of nuclei formed in the high-temperature alloy melt increases, the grain size of the ingot is reduced, and the mechanical properties and thermoplasticity are improved. Finally, through high-temperature homogenization treatment, the segregation of alloy elements in the ingot is basically eliminated, and a low-segregation high-temperature alloy ingot is obtained, which significantly improves the hot working plasticity of the ingot.

[0026] b) The ingot prepared by the method of the present invention can be directly used for blanking and forging without the need for an electroslag remelting process and a vacuum consumable process, thereby significantly reducing the preparation cost of the ingot.

[0027] c) The high-temperature alloy low-segregation ingot of the present invention has small segregation, no carbide segregation phenomenon, fine grain size, good organizational uniformity, and excellent toughness and plasticity. For example, the element segregation coefficients at the center of the ingot are as follows: Ti: 1.09-1.15, Mo: 1.00-1.03, Cr: 0.98-1.00, Co: 0.96-1.00; the element segregation coefficients at the edge of the ingot are as follows: Ti: 1.04-1.10, Mo: 1.02-1.11, Cr: 0.98-1.00, Co: 0.98-1.00; the grain size of the ingot is about 120-160 μm, and the grains are fine. The hardness fluctuation from the center to the edge of the ingot is small, for example, the hardness difference from the center to the edge of the ingot is less than 3HRC.

[0028] d) The room temperature tensile strength of the high-temperature alloy low segregation ingot of the present invention is 680 MPa or more (e.g. 681-700 MPa), the yield strength is 440 MPa or more (e.g. 442-460 MPa), the elongation after fracture is 20% or more (e.g. 20.5%-23.5%), and the reduction of area is 40% or more (e.g. 42%-49%); the properties of the ingot at 650°C are as follows: tensile strength is 590 MPa or more (e.g. 597-620 MPa), yield strength is 350 MPa or more (e.g. 350-370 MPa), elongation after fracture is 26% or more (e.g. 26.5%-29%), and reduction of area is 32% or more (e.g. 32%-35%).

[0029] Other features and advantages of the present invention will be described in the following description, and part of them will become obvious from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the contents particularly pointed out in the written description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0031] Figure 1 This is a low-magnification image of the ingot in Example 1;

[0032] Figure 2 This is a low-magnification image of the ingot in Comparative Example 1;

[0033] Figure 3 is a carbide morphology diagram of the ingot in Example 1;

[0034] Figure 4 This is the carbide morphology of the ingot in Comparative Example 1. DETAILED DESCRIPTION

[0035] Preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used to explain the principles of the present invention together with the embodiments of the present invention.

[0036] The present invention provides a method for preparing a high-temperature alloy low-segregation ingot, comprising the following steps:

[0037] Step 1, smelting to obtain alloy liquid;

[0038] Step 2, pouring the alloy liquid, applying pulse electromagnetic treatment to the alloy liquid after the pouring starts, continuing to apply the pulse electromagnetic after the pouring process is completed, and turning off the pulse electromagnetic after a certain period of time to obtain an ingot;

[0039] Step 3: homogenize the ingot to obtain a high-temperature alloy low-segregation ingot.

[0040] Specifically, in the above step 1, the smelting is carried out in an induction furnace. Considering that when the smelting temperature is lower than 1500°C, it is difficult for the high-temperature alloy raw materials to be completely melted, and the composition is uneven; when the smelting temperature is higher than 1600°C, the supercooling of the alloy is reduced, and the as-cast structure of the ingot is easy to coarsen. At the same time, the higher smelting temperature is easy to cause the induction coil to burn out, resulting in a weakening of the magnetic field. Therefore, the smelting temperature is controlled to be 1500-1600°C, and the smelting power is 20-60KW.

[0041] Specifically, in the above step 1, low power smelting is first adopted in the early stage of smelting, and then the power is gradually increased to melt all the raw materials, and after all the raw materials are melted, they are kept warm for 5 to 10 minutes before pouring.

[0042] Specifically, in the above step 2, the cast ingot mold is placed in the furnace of a circular heating furnace, and the furnace of the circular heating furnace is placed in a stainless steel pipe; the stainless steel pipe is used to support the heating furnace and the ingot mold; a large amount of refractory material is filled between the heating furnace and the stainless steel pipe; an induction coil is provided around the stainless steel pipe, and the current and waveform in the induction coil are controlled by a power supply device to perform magnetic field treatment on the cast high-temperature alloy melt.

[0043] Specifically, in the above step 2, an electric control cabinet may be used to apply pulse electromagnetic to the high-temperature alloy melt.

[0044] Specifically, in the above step 2, the stainless steel pipe is made of 316 austenitic stainless steel. The wall thickness of the stainless steel pipe is 20-25 mm.

[0045] Specifically, in the above step 2, the ingot mold is preheated by a heating furnace before pouring. Considering that when the preheating temperature is less than 400°C, the temperature inside and outside the ingot increases, and thermal cracks are prone to appear on the surface of the ingot, increasing the preheating temperature of the ingot mold can effectively reduce the thermal stress and strain during the solidification process of the ingot, while improving the ability of the liquid metal to compensate for shrinkage in the later stage of the ingot, thereby achieving the effect of controlling the generation of thermal cracks during the solidification process; when the preheating temperature of the ingot mold exceeds 600°C, the ingot mold needs to be heated for too long, and at the same time, the stress at the chamfer of the inner wall of the ingot mold does not decrease significantly; taking all factors into consideration, the preheating temperature is controlled to be 400-600°C.

[0046] Specifically, in the above step 2, the waveform of the pulse electromagnetic is a rectangular wave. The use of a rectangular wave can accurately control the time for the pulse electromagnetic to act on the alloy melt.

[0047] Specifically, in the above step 2, the pulse electromagnetic current I and the ingot diameter d meet the following relationship: I=kd, the value range of k is 0.6-1, the unit of I is A, and the unit of d is mm.

[0048] Preferably, the ingot diameter d is 100-120 mm, and the pulse electromagnetic current I is 60-80 A;

[0049] The ingot diameter d is 150-170 mm, and the pulse electromagnetic current I is 100-150 A;

[0050] The ingot diameter d is 200-220 mm, and the pulse electromagnetic current I is 160-200 A;

[0051] The ingot diameter d is 250-270 mm, and the pulse electromagnetic current I is 210-230 A;

[0052] The ingot diameter d is 300-320 mm, and the pulse electromagnetic current I is 250-300 A.

[0053] Specifically, in the above step 2, the current duty cycle of the pulse electromagnetic is 20% to 40%, for example, 23%, 25%, 30%, 35%; the frequency is 25 to 36 Hz, for example, 27 Hz, 30 Hz, 32 Hz.

[0054] It should be noted that in the above step 2, it is necessary to accurately control the start time and end time of the pulse electromagnetic, as well as the specific process parameters of the pulse electromagnetic. Through the above precise control, the segregation of the elements in the high-temperature alloy ingot can be reduced, and the grain size is small. The control of the above process steps and parameters can ensure that the thermodynamic conditions for improving the segregation of alloy elements can be formed inside the alloy melt. When the current output is too small, the Lorentz force of the electromagnetic field is small, the stirring effect on the high-temperature alloy solute solution is weak, the driving force for the movement of the micro-area melt at the solidification front is small, and the alloy elements are difficult to fully diffuse; when the current is too large, the high-temperature alloy melt is stirred violently, which is easy to produce greater alloy element segregation and shrinkage cavities; when the frequency is less than 25HZ, it cannot effectively promote the vibration of the solid solution interface of the high-temperature alloy melt, the solute concentration at the interface is low and the solute flow is weak, when the frequency is higher than 35Hz, the solute concentration at the interface is high and the solute flow is enhanced, the solute flow is prone to disorder, causing greater segregation; therefore, the control frequency is between 25HZ and 35Hz, and the solute can be evenly distributed and has good fluidity. When the duty cycle is less than 20%, the edge area of ​​the ingot is easily affected by the pulsed magnetic field, but the core area is almost unaffected, resulting in poor cross-sectional structural uniformity and uneven distribution of solute elements; when the duty cycle is greater than 40%, the intermittent nature of the pulse is lost, the heat transfer capacity of the melt is reduced, and the continuous high temperature makes it difficult for the melt to nucleate, and the effect of the pulsed magnetic field on reducing segregation and refining grains is gradually weakened.

[0055] Specifically, in the above step 2, the pulse electromagnetic is continued after the pouring process is completed, and the pulse electromagnetic is turned off after 60 to 100 seconds. This is because when the electromagnetic action time is less than 60 seconds, the ingot is not completely solidified, and the electromagnetic field still works; when the electromagnetic action time is more than 100 seconds, the ingot is completely solidified, and the effect of the electromagnetic field on the solidification structure is significantly weakened.

[0056] Specifically, in the above step 3, the homogenization process includes the following steps:

[0057] S301, keeping the ingot at 650-750°C;

[0058] S302, heating to 1000-1020°C, keeping warm;

[0059] S303, heating to 1150-1170°C, keeping warm;

[0060] S304, heating to 1200-1220°C, keeping warm;

[0061] S305, cool down to 950-1050℃, keep warm; after taking out of the furnace, air cool to room temperature.

[0062] Specifically, the insulation time T1 of S301, the insulation time T2 of S302, the insulation time T3 of S303, and the insulation time T4 of S304 satisfy the following relationship: T1<T2, T3<T4.

[0063] Specifically, the heating rate V1 in S302, the heating rate V2 in S303, and the heating rate V3 in S304 satisfy the following relationship: V1>V2>V3.

[0064] Specifically, the insulation time of the above S301 is 3 to 5 hours, for example, 3.5 hours, 4 hours, and 4.5 hours; the insulation time of S302 is 15 to 25 hours, for example, 17 hours, 20 hours, and 23 hours; the insulation time of S303 is 15 to 25 hours, for example, 17 hours, 20 hours, and 23 hours; the insulation time of S304 is 60 to 80 hours, for example, 63 hours, 65 hours, 67 hours, 70 hours, 73 hours, 75 hours, and 77 hours.

[0065] Specifically, the heating rate V1 in the above S302 is 40-50°C / h, for example, 43°C / h, 45°C / h, 47°C / h; the heating rate V2 in S303 is 20-30°C / h, for example, 23°C / h, 25°C / h, 27°C / h; the heating rate V3 in S304 is 5-10°C / h, for example, 7°C / h, 8°C / h, 9°C / h.

[0066] Specifically, the cooling rate V4 in the above S305 is 45-50°C / h, for example, 47°C / h, 48°C / h, 49°C / h.

[0067] Specifically, the insulation time in the above S305 is 0.5 to 1 h, for example, 0.6 h, 0.7 h, 0.8 h, or 0.9 h.

[0068] It should be noted that in the homogenization process of step 3, the temperature is first kept at 650-750°C to prevent the ingot from cracking due to a large temperature difference between the inside and outside of the ingot caused by too fast a temperature rise or too high a temperature; then the temperature is quickly raised to 1000-1020°C and then kept, so that the low melting point phase σ and carbide M 23C6 is fully dissolved in the matrix; then the temperature is raised to 1150-1170°C at a faster heating rate and kept warm to continue to dissolve the low melting point phase η and the boride; finally, the temperature is raised to 1200-1220°C at a slower heating rate to accelerate the diffusion of alloy elements and reduce microsegregation. Finally, the composition segregation and organization segregation of the ingot are significantly reduced by adopting the above-mentioned multi-stage homogenization process, an ingot with uniform composition and organization is obtained, and the plasticity of the ingot is improved.

[0069] Specifically, during the homogenization treatment process of the above step 3, the temperature is first lowered to 950-1050°C and then kept warm and then cooled. At this time, the high-temperature alloy is in the γ+γ′ dual-phase region, a dual-phase structure is obtained, the grain boundary state is improved, the thermoplasticity of the high-temperature alloy is further improved, and the alloy is further prevented from cracking during blanking, thereby realizing blanking forging of difficult-to-deform high-temperature alloys.

[0070] Compared with the prior art, in the preparation method of the high-temperature alloy low-segregation ingot of the present invention, pulse electromagnetic treatment is applied to the alloy liquid after the pouring begins. Under the action of the electromagnetic field, the solute fluidity at the solidification interface front is increased, the solute elements can be fully mixed, the segregation degree of the ingot is significantly reduced, and the segregation behavior of the carbide is suppressed, and the uniformity of the alloy composition is improved; and during the pulse magnetic field treatment, convection movement occurs inside the alloy melt, the crystal nuclei on the mold wall fall off and become free, which increases the number of crystal nuclei in the alloy, promotes the formation of a large number of equiaxed crystals in the ingot, and the ingot structure is significantly refined, the columnar crystals are suppressed, and the segregation of alloy elements in the ingot is also reduced; the number of nuclei in the high-temperature alloy melt increases, the grain size of the ingot is reduced, and the mechanical properties and thermoplasticity are improved. Finally, through high-temperature homogenization treatment, the segregation of alloy elements in the ingot is basically eliminated, and a low-segregation high-temperature alloy ingot is obtained, which significantly improves the hot working plasticity of the ingot.

[0071] The ingot prepared after the homogenization treatment can be directly used for blanking and forging without the need for an electroslag remelting process and a vacuum consumable process, thereby significantly reducing the preparation cost of the ingot.

[0072] The present invention also provides a high-temperature alloy low-segregation ingot, which is prepared by the above-mentioned preparation method.

[0073] Specifically, the components of the above-mentioned high-temperature alloy, by mass percentage, include C: 0.02% to 0.10%, Cr: 18.0% to 21.0%, Co: 13.0% to 14.0%, Mo: 3.50% to 5.00%, Al: 1.2% to 1.6%, Ti: 2.80% to 3.3%, and nickel: the balance.

[0074] The high-temperature alloy low-segregation ingot of the present invention has small segregation, no carbide segregation phenomenon, fine grain size, good organizational uniformity, and excellent toughness and plasticity. For example, the element segregation coefficients at the center of the ingot are as follows: Ti: 1.09-1.15, Mo: 1.00-1.03, Cr: 0.98-1.00, Co: 0.96-1.00; the element segregation coefficients at the edge of the ingot are as follows: Ti: 1.04-1.10, Mo: 1.02-1.11, Cr: 0.98-1.00, Co: 0.98-1.00; the grain size of the ingot is about 120-160 μm, and the grains are fine. The hardness fluctuation from the center to the edge of the ingot is small, for example, the hardness difference from the center to the edge of the ingot is less than 3HRC.

[0075] Specifically, the room temperature tensile strength of the above-mentioned high-temperature alloy low segregation ingot is above 680MPa (for example, 681-700MPa), the yield strength is above 440MPa (for example, 442-460MPa), the elongation after fracture is above 20% (for example, 20.5%-23.5%), and the cross-sectional reduction rate is above 40% (for example, 42%-49%); the performance of the ingot at 650°C is as follows: tensile strength is above 590MPa (for example, 597-620MPa), yield strength is above 350MPa (for example, 350-370MPa), elongation after fracture is above 26% (for example, 26.5%-29%), and cross-sectional reduction rate is above 32% (for example, 32%-35%).

[0076] The advantages of precise control of process parameters of the present invention are demonstrated below with specific examples and comparative examples.

[0077] Example 1

[0078] This embodiment provides a method for preparing a high-temperature alloy low-segregation ingot. The composition of the high-temperature alloy of this embodiment is shown in Table 1 below, and the method comprises the following steps:

[0079] The nickel-based high-temperature alloy raw material is placed in a 20kg induction furnace for smelting, the smelting temperature is 1550°C, and the smelting power is 20-60KW (low power smelting is first used in the early stage of smelting, and then the power is gradually increased to melt all the raw materials). After all the raw materials are melted, low power smelting is used again, and pouring is performed after keeping warm for 6 minutes;

[0080] Before pouring, the ingot mold is preheated to 600℃ by a heating furnace; after pouring begins, the electric control cabinet is quickly turned on to apply pulse electromagnetic to the high-temperature alloy melt, where the output current of the electric control cabinet is 70A, the duty cycle is 30%, the frequency is 30HZ, and the electromagnetic waveform is a rectangular wave; after the pouring process is completed, the pulse electromagnetic is continued, and the pulse electromagnetic is turned off after 70s to obtain an ingot; the ingot size is

[0081] Subsequently, the ingot was subjected to a high-temperature, long-term homogenization treatment: the ingot was kept at 700°C for 4 hours; then the temperature was increased to 1020°C at 48°C / h and kept for 25 hours; then the temperature was increased to 1160°C at 25°C / h and kept for 25 hours; then the temperature was increased to 1200°C at 10°C / h and kept for 70 hours; finally, the ingot was cooled to 1000°C at 48°C / h and kept for 1 hour, and then air-cooled to room temperature after being taken out of the furnace.

[0082] Example 2

[0083] This embodiment provides a method for preparing a high-temperature alloy low-segregation ingot. The composition of the high-temperature alloy of this embodiment is shown in Table 1 below, and the method comprises the following steps:

[0084] The nickel-based high-temperature alloy raw material is placed in a 20kg induction furnace for smelting, the smelting temperature is 1580°C, the smelting power is 20-60KW (low power smelting is first used in the early stage of smelting, and then the power is gradually increased to melt all the raw materials), and after all the raw materials are melted, they are kept warm for 10 minutes before pouring;

[0085] Before pouring, the ingot mold is preheated to 600℃ by a heating furnace; after pouring begins, the electric control cabinet is quickly turned on to apply pulse electromagnetic to the high-temperature alloy melt, where the output current of the electric control cabinet is 74A, the duty cycle is 32%, the frequency is 28HZ, and the electromagnetic waveform is a rectangular wave; after the pouring process is completed, the pulse electromagnetic is continued, and the pulse electromagnetic is turned off after 80s to obtain an ingot; the ingot size is

[0086] Subsequently, the ingot was subjected to a high-temperature, long-term homogenization treatment: the ingot was kept at 700°C for 4 hours; then the temperature was increased to 1020°C at 47°C / h and kept for 20 hours; then the temperature was increased to 1170°C at 25°C / h and kept for 20 hours; then the temperature was increased to 1220°C at 8°C / h and kept for 70 hours; finally, the ingot was cooled to 1000°C at 46°C / h and kept for 0.5 hours, and then air-cooled to room temperature after being taken out of the furnace.

[0087] Example 3

[0088] This embodiment provides a method for preparing a high-temperature alloy low-segregation ingot. The composition of the high-temperature alloy of this embodiment is shown in Table 1 below, and the method comprises the following steps:

[0089] (1) Place the nickel-based high-temperature alloy raw material in a 20kg induction furnace for smelting at a smelting temperature of 1560°C and a smelting power of 20 to 60KW (in the early stage of smelting, low power smelting is first used, and then the power is gradually increased to melt all the raw materials). After all the raw materials are melted, keep warm for 10 minutes before pouring;

[0090] (2) Before pouring, the ingot mold is preheated to 590°C by a heating furnace; after pouring begins, the electric control cabinet is quickly turned on to apply pulse electromagnetic to the high-temperature alloy melt, wherein the output current of the electric control cabinet is 120A, the duty cycle is 35%, the frequency is 36HZ, and the electromagnetic waveform is a rectangular wave; after the pouring process is completed, the pulse electromagnetic is continued to act, and the pulse electromagnetic is turned off after 90s to obtain an ingot; the ingot size is

[0091] (3) The ingot is then subjected to a high-temperature, long-term homogenization treatment: the ingot is kept at 750°C for 5 hours; then the temperature is increased to 1020°C at 40°C / h and kept at this temperature for 25 hours; then the temperature is increased to 1170°C at 20°C / h and kept at this temperature for 25 hours; then the temperature is increased to 1220°C at 10°C / h and kept at this temperature for 80 hours; finally, the ingot is cooled to 1050°C at 45°C / h and kept at this temperature for 1 hour, and then air-cooled to room temperature after being taken out of the furnace.

[0092] The inventor has conducted a lot of research during the research process, and now uses some solutions with poor performance as comparative examples.

[0093] Comparative Example 1

[0094] This comparative example provides a method for preparing a high-temperature alloy low-segregation ingot. The components of the high-temperature alloy in this comparative example are the same as those in Example 1, and the overall steps of the preparation method are the same as those in Example 1, except that:

[0095] (2) During pouring, the current is 50A, the duty cycle is 10%, and the frequency is 20HZ; after the pouring process is completed, the pulse electromagnetic is continued to act, and the pulse electromagnetic is turned off after 30s.

[0096] Comparative Example 2

[0097] This comparative example provides a method for preparing a high-temperature alloy low-segregation ingot. The components of the high-temperature alloy in this comparative example are the same as those in Example 1, and the overall steps of the preparation method are the same as those in Example 1, except that:

[0098] (2) During pouring, the current is 50A;

[0099] (3), the ingot is heated to 1010°C at 45°C / h and kept at this temperature for 30h; then heated to 1190°C at 10°C / h and kept at this temperature for 80h; finally, cooled to 1000°C at 46°C / h and kept at this temperature for 0.5h, and then air-cooled to room temperature after being taken out of the furnace.

[0100] The chemical compositions of the examples are shown in Table 1 below.

[0101] The ingots obtained in Example 1 and Comparative Example 1 were sampled by wire cutting. Figure 1 As shown, the ingot of Comparative Example 1 is low-multiple Figure 2After comparison, it is found that the riser of the ingot of Example 1 after magnetic field treatment is significantly smaller than that of Comparative Example 1.

[0102] The grain sizes of the ingots of the embodiment and the comparative example are shown in Table 2 below. It can be seen that the grain size of the ingot of the embodiment of the present invention is finer than that of the comparative example. For example, the grain size of the ingot of the embodiment is 120-160 μm.

[0103] The carbides in the ingot of Example 1 are as follows Figure 3 As shown, the carbides in the ingot of Comparative Example 1 are as follows Figure 4 As shown, it can be seen that no carbide segregation occurs in Example 1.

[0104] The segregation coefficients of Ti, Mo, Cr and Co of the ingots of the embodiment and the comparative example are shown in Table 3; it can be seen that the ingot of the present invention has a smaller degree of segregation and better composition uniformity.

[0105] The hardness fluctuation from the center to the edge of the ingot in the embodiment is small, and the mechanical properties are significantly improved. For example, the hardness difference from the center to the edge of the ingot is less than 3HRC. The hardness difference from the center to the edge of the ingot in Comparative Example 1 reaches 8HRC, and the hardness difference from the center to the edge of the ingot in Comparative Example 2 reaches 7HRC. It can be seen that the composition and performance of the ingot of the present invention are more uniform and stable.

[0106] The properties of the embodiments and comparative examples are shown in Table 4 below. It can be seen that the ingot of the present invention has good thermoplasticity.

[0107] Table 1 Chemical composition, wt%

[0108] serial number C Cr Co Mo Al Ti Example 1 0.035 19.29 13.28 4.46 1.59 3.12 Example 2 0.031 19.46 13.54 4.34 1.45 3.18 Example 3 0.034 19.12 13.25 4.31 1.42 3.07

[0109] Table 2 Grain size of ingot

[0110] serial number Grain size / μm Example 1 120～150 Example 2 130～160 Example 3 120～160 Comparative Example 1 190～220 Comparative Example 2 180～220

[0111] Table 3 Alloy element segregation coefficient

[0112]

[0113]

[0114] Table 4 Ingot performance test results

[0115]

[0116] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for preparing a high-temperature alloy low-segregation ingot, characterized in that: The steps include: Step 1, smelting to obtain alloy liquid; Step 2, pouring the alloy liquid into the ingot mold, applying pulse electromagnetic treatment to the alloy liquid after the pouring starts, continuing to apply the pulse electromagnetic after the pouring process is completed, and turning off the pulse electromagnetic after 60 to 100 seconds to obtain an ingot; Step 3: homogenize the ingot to obtain a high-temperature alloy low-segregation ingot.

2. The preparation method according to claim 1, characterized in that: In the step 2, the ingot mold is preheated in a heating furnace before pouring, and the preheating temperature is 400-600°C.

3. The preparation method according to claim 1, characterized in that: In step 2, the waveform of the pulse electromagnetic is a rectangular wave.

4. The preparation method according to claim 3, characterized in that: In the step 2, the pulse electromagnetic current I and the ingot diameter d meet the following relationship: I=kd, the value range of k is 0.6-1, the unit of I is A, and the unit of d is mm.

5. The preparation method according to claim 4, characterized in that: In step 2, the ingot diameter d is 100-120 mm, and the pulse electromagnetic current I is 60-80 A; the ingot diameter d is 150-170 mm, and the pulse electromagnetic current I is 100-150 A; the ingot diameter d is 200-220 mm, and the pulse electromagnetic current I is 160-200 A.

6. The preparation method according to claim 1, characterized in that: In step 2, the current duty cycle of the pulse electromagnetic is 20% to 40%.

7. The preparation method according to claim 1, characterized in that: In step 3, the homogenization process comprises the following steps: S301, keeping the ingot at 650-750°C; S302, heating to 1000-1020°C, keeping warm; S303, heating to 1150-1170°C, keeping warm; S304, heating to 1200-1220°C, keeping warm; S305, cool down to 950-1050℃, keep warm; after taking out of the furnace, air cool to room temperature.

8. The preparation method according to claim 7, characterized in that: In step 3, the insulation time T1 of S301, the insulation time T2 of S302, the insulation time T3 of S303, and the insulation time T4 of S304 meet the following relationship: T1<T2, T3<T4.

9. The preparation method according to claim 7, characterized in that: In step 3, the heating rate V1 in S302, the heating rate V2 in S303, and the heating rate V3 in S304 satisfy the following relationship: V1>V2>V3.

10. A high temperature alloy low segregation ingot, characterized in that: The high-temperature alloy low-segregation ingot is prepared by the preparation method according to any one of claims 1 to 9.

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