CN103484802B - Preparation method for obtaining kilogram-grade high temperature alloy undercooled melt - Google Patents

Abstract

The invention discloses a preparation method for obtaining a supercooled melt of a kilogram-level superalloy. The present invention adopts the medium-frequency induction power supply as the heating power supply, generates convection through medium-frequency induction heating, and makes the macroscopic temperature field of the melt more uniform, so as to ensure that the melt is cooled uniformly at the same time. The high-purity quartz crucible is used as the heating crucible, and the B ₂ O ₃ glass melting covering agent is used as the purifying agent or protected by argon gas, and the melt is purified by multiple cycles of overheating treatment. By controlling the overheating temperature, holding temperature and circulation times to achieve the best purification effect. The cooling rate is reasonably controlled, and the temperature difference between the inside and outside of the melt is limited within 3°C, so that the entire melt can be uniformly cooled at the same time. The temperature field and the uniformity of the melt structure obtained by the invention are relatively good, and the kilogram-level supercooled melt is in a supercooled state as a whole, and the fluidity of the supercooled melt is good, and the solid phase ratio is lower than 0.2%. The invention is applicable to the field of micro-casting, and the overall fine-grained ingot can be obtained by controlling the subsequent cooling speed of the kilogram-level supercooled melt.

Description

A preparation method for obtaining supercooled melt of kilogram-level superalloy

technical field

The invention relates to the field of supercooled solidification of superalloys, in particular to a preparation method for obtaining kilogram-level supercooled melts of superalloys.

Background technique

As an important means of grain refinement, melt treatment has been widely used in superalloys, and the acquisition of supercooled melt is the key process to ensure the successful solidification of fine grains. The thermal history of the melt before solidification and subsequent control The temperature method plays a vital role in obtaining fine-grained structure. By performing special temperature control on the melt, a better supercooled melt can be obtained. People have developed some methods of heat-controlled fine-grain casting of high-temperature alloys, and the methods that have been used in industry are mainly divided into: deep subcooling and ordinary heat-control methods.

People such as Li Delin wrote "The Fine Grainization of Bulk Deep Supercooled Ni-base Alloy" in "Chinese Journal of Nonferrous Metals", 1994,4 (1), p123-128, which reported the use of purifiers and cyclic superheating methods, Carry out 2-3 thermal cycles of "heating and melting-overheating and heat preservation-cooling and solidification", then cut off the high-frequency power supply, let the sample cool naturally, and obtain the structure of the alloy Ni ₇₇ Si ₁₃ B ₁₀ at an undercooling degree of 280°C. However, the uniformity of the structure is poor, and there are both developed dendrites and fine granular crystals; the reason is that when the power is cut off, the melt heats up unevenly inside and outside before nucleation, and a real deep supercooled melt cannot be obtained.

The Chinese Patent Office announced on October 12, 1999 (publication number: CN1232885) the invention patent application titled "A Method for the Solidification of Supercooled Melt of Atomic Clusters", which can directly introduce crystal nuclei into supercooled metal and alloy samples. Atomic clusters with the same size order can trigger and control the nucleation process to obtain the desired solidified structure. Although the above method can obtain a fine-grained structure, due to the sensitivity of the melt to the composition, the addition of atomic clusters may affect the properties of the alloy, and different alloys need to add different atomic clusters, which limits the application.

The Chinese Patent Office announced on March 23, 2005 (publication number: CN1598005) a patent application titled "A Method for Preparing Bulk Nanocrystalline Alloys from Deeply Supercooled Melts", which realized the prior solidification of metal samples to glass Slow cooling under wrapping to achieve deep supercooling and then rapid solidification, or use inert gas to blow the alloy melt into the metal mold for forced cooling of the cooling medium, rapid solidification to obtain bulk nanocrystalline alloy special-shaped parts can only stay in the theoretical research stage, Industrial applications are limited by the size of the ingot.

American P.C.C company has developed a thermally controlled solidification (TCS) technology from the sequential solidification technology, which makes the solidification interface of the casting advance sequentially, so that the cast can obtain a dense structure and good filling performance. The principle is that the melt is placed in a mold shell with heating equipment outside, the lower part of the melt is in contact with the copper plate, and the lower part of the copper plate is a rotatable cooling tray. When the melt moves downward with the copper plate, the melt outside the heating device can crystallize instantly, while the melt state inside the heating device is still in a complete liquid phase and can solidify while moving with the tray. However, this process can only be used for thin-walled parts, and this method cannot be used for thick castings.

The above-mentioned traditional methods for obtaining supercooled melts mainly focus on deep supercooled and small-volume supercooled melts, but there are few reports on actually obtaining kilogram-level supercooled melts with the entire melt in a supercooled state. Because high-frequency induction heating is usually used to obtain small-volume supercooled melt or deep supercooled, this heating method causes vibration of the melt due to electromagnetic stirring; when the melt is slowly cooled below the melting point, the vibration can easily cause nucleation. This phenomenon is especially serious under deep supercooling conditions. In order to obtain deep supercooled melts, the traditional solution is to turn off the power and quickly cool them above the melting point, which is acceptable for small-mass melts (a few grams to tens of grams). of. However, when the mass of the melt increases to the kilogram level, due to the limitation of heat dissipation, the melt before nucleation cannot be approximated as an isothermal melt. The inconsistency of coldness makes it impossible to obtain an overall supercooled melt.

In summary, for superalloys, it is hoped to develop a temperature control method that can obtain the overall melt in a supercooled state, and the acquisition of kilogram-level overall supercooled melt is the key process of the fine-grain solidification method. "A method for preparing a kilogram-level supercooled melt" can obtain a melt with good uniformity in the temperature field on the macroscopic scale, good uniformity in the melt structure on the microscopic scale, large volume and in an overall supercooled state. The supercooled melt also has the following characteristics: good fluidity and very low solid phase ratio (far below 0.2%). For superalloys, after searching the literature of the prior art, it is found that no public reports on obtaining kilogram-level supercooled melts through precise temperature control methods have been found, and no corresponding patent publications have been found.

Contents of the invention

In order to overcome the disadvantages existing in the prior art that when the mass of the melt increases to the kilogram level, the inconsistency between the melt surface and the internal supercooling degree, and the overall supercooled melt cannot be obtained, the present invention proposes a method for obtaining kilogram-level high temperature A method for preparing an alloy supercooled melt.

Concrete steps of the present invention are:

Step one, the selection of induction power frequency. Through the conductor resistivity ρ, the conductor permeability μ, according to formula (1) and formula (2), determine the power frequency f.

△H=d/n, (1)

In the formula, n is a constant; d is the diameter of the heated cylindrical melt in cm. According to the formula (1), the current penetration depth △H of the intermediate frequency induction power supply is determined.

$\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}{<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 5030</span>}}{\mathrm{<span\; class="notranslate">\; \&Delta;H</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

In the formula: ρ is the resistivity of the conductor in Ω cm; μ is the magnetic permeability of the conductor in H/cm; f is the frequency of the current in Hz. Both the conductor resistivity ρ and the conductor magnetic permeability μ are obtained according to the superalloy handbook.

Step two, the selection of the heating power of the power supply.

The heating power of the power supply is determined according to the formula (3).

y＝6.18exp(-x/17.32)+8.95 (3)

In the formula: y represents the heating power of the power supply, and the unit of heating power is kw; x represents the mass of the melt, and the unit is Kg; 6.18, 17.32 and 8.95 in the formula (3) are obtained by ANSYS software simulation calculation constant term.

Step three, preparation before melting. A layer of B ₂ O ₃ molten glass purification agent with a thickness of 3 mm is spread on the bottom of the quartz tube. Put the cleaned superalloy raw material into the quartz tube. The upper surface of the high-temperature alloy raw material is covered with a layer of B ₂ O ₃ molten glass purifying agent with a thickness of 3 mm, and the quartz tube is fixed on the induction coil of the intermediate frequency induction power supply.

Step 4, cyclic superheating treatment. Raise the temperature of the superalloy raw material to 100°C above the liquidus line of the superalloy under an intermediate frequency power supply and keep it warm for 5 minutes; after the heat preservation is completed, cool down to 50°C above the liquidus line of the superalloy. Repeat the above process of heating-heating-cooling for a total of 5 times, and repeatedly overheat the superalloy raw material to obtain a superheated melt of the superalloy.

Step five, cool down evenly. After repeated overheating of the superalloy raw material, the temperature of the superalloy raw material is lowered to 10 °C below the liquidus line of the melt at a cooling rate of 1.2-0.5 °C/min to obtain a kilogram-level supercooled melt.

The present invention can obtain a kilogram-level supercooled melt with good uniformity in temperature field and melt structure, and the whole is in a supercooled state, and the supercooled melt has good fluidity and a very low solid fraction (far below 0.2%) ).

The present invention is characterized in that:

First, use medium-frequency induction heating equipment that does not cause the skin effect of the melt, and use medium-frequency induction power as the heating power supply. The current penetration depth of the medium-frequency induction heating power supply is relatively deep. At the same time, convection is generated by medium-frequency induction heating, thereby making the macroscopic temperature field of the melt more uniform, which can ensure that the entire melt is cooled uniformly at the same time.

Second, in a limited heating mode, use a high-purity quartz crucible as a heating crucible, and use B ₂ O ₃ glass melting covering agent as a purifying agent or argon protection. Multiple cycles of superheating are used to purify the melt. Factors that can be controlled include superheating temperature, heat preservation temperature, and cycle times, and the parameters can be adjusted reasonably to achieve the best purification effect.

Thirdly, the cooling rate is reasonably controlled through program temperature control. Melts with different volumes have their optimal cooling rates, especially below the melting point. The limit is within 3°C, so that the entire melt can be cooled evenly at the same time.

In the present invention, when the medium-frequency induction heating equipment acts on the melt, the forced convection and thermal effect produced by the alternating electromagnetic field act dually, which accelerates the swimming rate of the atomic group (increases the diffusion rate), increases the number of mutual collisions and combinations, and macroscopically On the one hand, the temperature field and concentration field of the melt are more uniform; on the microscopic level, the size and distribution of atomic groups in the melt are more uniform, and the shape is more regular, and finally a kilogram-level supercooled melt is obtained. As the temperature further decreases, the atomic groups in the melt rapidly grow to the critical nucleation size, and a large number of uniformly distributed and regular-shaped atomic groups will grow into stable crystallization cores and form stable embryos. The thermal environment in the body is relatively uniform, and the existence of the induced magnetic field increases the nucleation rate, so the melt solidifies simultaneously to form a fine-grained solidified structure.

The invention highlights the importance of the heating method to obtain kilogram-level supercooled melt under the condition of scientific and reasonable power supply frequency and power selection, so that the melt can obtain a real kilogram-level supercooled melt under slow cooling conditions, which can A melt with good uniformity of the temperature field on the macroscopic scale, good uniformity of the melt structure on the microscopic scale, large volume and overall supercooled state is obtained. The supercooled melt also has the following characteristics: good fluidity and very low solid phase ratio (far below 0.2%). Finally, a coagulated structure with overall uniform refinement was obtained.

The kilogram-level supercooled melt obtained in the present invention provides slurry for thixotropic deformation and rheological deformation, and is suitable for the field of micro-casting. By controlling the subsequent cooling speed of the kilogram-level supercooled melt, an overall fine-grained ingot can be obtained.

Description of drawings

Fig. 1 is the cross-sectional structure of the ingot after the melt is solidified in the first embodiment.

Fig. 2 is the metallographic photograph of the ingot after the melt is solidified in embodiment one, wherein Fig. 2 (a), Fig. 2 (b) and Fig. 2 (c) are ingot edge, 1/4 place and central part respectively Microstructure.

Fig. 3 is a physical view of the superalloy casting in Example 2, wherein Fig. 3a is a top view of the superalloy casting, and Fig. 3b is a side view of the superalloy casting.

Fig. 4 is a macroscopic photo of the superalloy ingot in Example 3.

Fig. 5 is the metallographic photograph of the superalloy ingot in Example 3, wherein Fig. 5 (a), Fig. 5 (b) and Fig. 5 (c) are respectively the ingot edge and 1/4 of the A section in Fig. 4 , The metallographic structure of the central part.

Fig. 6 is a flowchart of the present invention.

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Detailed ways

Embodiment one

This embodiment is a preparation method for obtaining a supercooled melt of a kilogram-level superalloy with a solid-liquid two-phase region of 30-80°C. The superalloy is K4169 superalloy, and the mass of the K4169 superalloy is 0.5Kg. The specific implementation is carried out in the intermediate frequency induction power supply, and its specific steps are:

Step one, the selection of induction power frequency. The conductor resistivity ρ and the conductor magnetic permeability μ are obtained according to the superalloy manual, and according to formula (1) and formula (2), the frequency of the intermediate frequency power supply is finally determined to be 30KHz.

△H=d/n, (1)

In the formula, n is a constant. According to the formula (1), the current penetration depth △H of the intermediate frequency induction power supply is determined.

$\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}{<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 5030</span>}}{\mathrm{<span\; class="notranslate">\; \&Delta;H</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

In the formula: ρ is the resistivity of the conductor in Ω cm; μ is the magnetic permeability of the conductor in H/cm; f is the frequency of the current in Hz. Both the conductor resistivity ρ and the conductor magnetic permeability μ are obtained according to the superalloy handbook. According to the formula (2) determine the frequency f of the power supply.

According to the formula (1) and formula (2), the power frequency f of the melt is obtained.

Step two, the selection of the heating power of the power supply.

The heating power of the power supply is determined according to the formula (3).

y＝6.18exp(-x/17.32)+8.95 (3)

In the formula: y represents the heating power of the power supply, and the unit of heating power is kw; x represents the mass of the melt, and the unit is Kg; 6.18, 17.32 and 8.95 in the formula (3) are obtained by ANSYS software simulation calculation constant term. Obtain melts of different qualities to obtain supercooled melt power supply heating power as shown in Table 1:

Table 1: Power supply heating power corresponding to different quality melts

High temperature alloy/kg J _S /(10 ⁶ A/m ² ) P/kw 0.5 23.3 14.2 2 21.2 13.1 10 19.8 12.4 20 17.6 11 30 16 10

According to Table 1, the optimum power frequency of this embodiment is 14.2Kw.

Step three, preparation before melting. Take a quartz tube with a diameter of Φ35mm and a height of 50mm, and spread a layer of _B2O3 molten glass purification agent with a thickness of _3mm on the bottom of the quartz tube. Put the K4169 superalloy raw material that has been ultrasonically cleaned with alcohol and acetone into a quartz tube. Cover the upper surface of the K4169 superalloy raw material with a layer of 3mm thick B ₂ O ₃ molten glass purifier, and finally fix the quartz tube on the induction coil of the intermediate frequency induction power supply.

Step 4, cyclic superheating treatment. The superalloy raw material was heated up to 1450°C under a 30KHz intermediate frequency power supply. When the superalloy raw material is heated to 1450°C and kept for 5 minutes, the temperature is lowered to 1400°C after the heat preservation is completed. Repeat the above process of heating-heating-cooling for a total of 5 times, and repeatedly overheat the superalloy raw material to obtain a superheated melt of the superalloy.

Step five, cool down evenly. After the repeated superheating treatment of the superalloy raw material, the temperature of the superalloy raw material is lowered to 10 °C below the liquidus line of the melt at a cooling rate of 1.2-0.5 °C/min, that is, 1340 °C to obtain a kilogram-level supercooled melt . Turn off the induction power supply to air-cool the melt to obtain a superalloy ingot. In this embodiment, the cooling rate of the superalloy raw material is 1.2°C/min, and the liquidus line of the melt is 1350°C.

Embodiment two

The specific implementation process of this example is as follows: This example is a preparation method of a 2Kg Ni-22Cr-18W-1Mo superalloy supercooled melt.

The material involved in this example is a Ni-22Cr-18W-1Mo superalloy, which is a self-developed nickel-based deformed superalloy that is solid solution strengthened and carbide dispersion strengthened. The Ni-22Cr-18W-1Mo superalloy was disclosed in the paper "Secondary M23C6 Precipitation Behavior of Ni-22Cr-18W-1Mo-based Superalloy" by Bai Guanghai et al. in 2009.

Step one, the selection of induction power frequency. The conductor resistivity ρ and conductor magnetic permeability μ are obtained from the superalloy handbook, and according to formula (1) and formula (2), the frequency of the intermediate frequency power supply is finally determined to be 4KHz.

△H=d/n, (1)

In the formula, n is a constant. According to the formula (1), the current penetration depth △H of the intermediate frequency induction power supply is determined.

$\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}{<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 5030</span>}}{\mathrm{<span\; class="notranslate">\; \&Delta;H</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

In the formula: ρ is the resistivity of the conductor in Ω cm; μ is the magnetic permeability of the conductor in H/cm; f is the frequency of the current in Hz. Both the conductor resistivity ρ and the conductor magnetic permeability μ are obtained according to the superalloy handbook. According to the formula (2) determine the frequency f of the power supply.

According to the formula (1) and formula (2), the power frequency f of the melt is obtained.

Step two, the selection of the heating power of the power supply.

The heating power of the power supply is determined according to the formula (3).

y＝6.18exp(-x/17.32)+8.95 (3)

In the formula: y represents the heating power of the power supply, and the unit of heating power is kw; x represents the mass of the melt, and the unit is Kg; 6.18, 17.32 and 8.95 in the formula (3) are obtained by ANSYS software simulation calculation constant term. Obtain melts of different qualities to obtain supercooled melt power supply heating power as shown in Table 1:

Table 1: Power supply heating power corresponding to different quality melts

High temperature alloy/kg J _S /(10 ⁶ A/m ² ) P/kw 0.5 23.3 14.2 2 21.2 13.1 10 19.8 12.4 20 17.6 11 30 16 10

According to Table 1, the optimum power frequency of this embodiment is 13.1Kw.

Step three, preparation before melting. Put 2Kg of Ni-22Cr-18W-1Mo superalloy raw material into a quartz crucible, protect it with argon gas when the vacuum degree is 10 ^-2 Pa, and start overheating when the pressure of argon gas is 0.5 Pa.

Step 4, cyclic superheating treatment. The superalloy raw material was heated up to 1500°C under a 4KHz intermediate frequency power supply. When the temperature of the superalloy raw material is raised to 1450°C and kept for 10 minutes, the temperature is lowered to 1450°C after the heat preservation is completed. Repeat the above process of heating-heating-cooling for a total of 5 times, and repeatedly overheat the superalloy raw material to obtain a superheated melt of the superalloy. The temperature measuring device used in this embodiment is an infrared thermometer with a temperature control accuracy better than 1° C., and a response rate of less than 10 ms.

Step five, cool down evenly. After repeated overheating of the superalloy raw material, the temperature is lowered slowly at a rate of 1.5-1.0°C/min until the liquidus line of the melt is 1400°C. At this time, a kilogram-level supercooled melt is obtained. Then it was poured at a pouring speed of 5.11kg/s into a mold shell with a preheating temperature of 1000°C, and finally the solid part in Example 2 was obtained. In this embodiment, the cooling rate of the superalloy melt is 1.5°C/min, and the liquidus of the melt is 1400°C.

Embodiment three

The specific implementation process of this example is: The specific implementation process of this example is: This embodiment is a preparation method of a 30Kg Ni-22Cr-18W-1Mo superalloy supercooled melt.

Step one, the selection of induction power frequency. The conductor resistivity ρ and the conductor magnetic permeability μ are obtained from the superalloy handbook, and according to formula (1) and formula (2), the frequency of the intermediate frequency power supply is finally determined to be 400 Hz.

△H=d/n, (1)

In the formula, n is a constant. According to the formula (1), the current penetration depth △H of the intermediate frequency induction power supply is determined.

$\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}{<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 5030</span>}}{\mathrm{<span\; class="notranslate">\; \&Delta;H</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

In the formula: ρ is the resistivity of the conductor in Ω cm; μ is the magnetic permeability of the conductor in H/cm; f is the frequency of the current in Hz. Both the conductor resistivity ρ and the conductor magnetic permeability μ are obtained according to the superalloy handbook. According to the formula (2) determine the frequency f of the power supply.

According to the formula (1) and formula (2), the power frequency f of the melt is obtained.

Step two, the selection of the heating power of the power supply.

The heating power of the power supply is determined according to the formula (3).

y＝6.18exp(-x/17.32)+8.95 (3)

In the formula: y represents the heating power of the power supply, and the unit of heating power is kw; x represents the mass of the melt, and the unit is Kg; 6.18, 17.32 and 8.95 in the formula (3) are obtained by ANSYS software simulation calculation constant term. Obtain melts of different qualities to obtain supercooled melt power supply heating power as shown in Table 1:

Table 1: Power supply heating power corresponding to different quality melts

High temperature alloy/kg J _S /(10 ⁶ A/m ² ) P/kw 0.5 23.3 14.2 2 21.2 13.1 10 19.8 12.4 20 17.6 11 30 16 10

According to Table 1, the optimum power frequency of this embodiment is 10Kw.

Step three, preparation before melting. Put 30Kg of Ni-22Cr-18W-1Mo superalloy raw material into a quartz crucible, protect it with argon gas when the vacuum degree is 10 ^-2 Pa, and start overheating when the pressure of argon gas is 0.5 Pa.

Step 4, cyclic superheating treatment. The superalloy raw material was heated to 1500°C under a 400Hz intermediate frequency power supply. When the temperature of the superalloy raw material is raised to 1450°C and kept for 10 minutes, the temperature is lowered to 1450°C after the heat preservation is completed. Repeat the above process of heating-heating-cooling for a total of 5 times, and repeatedly overheat the superalloy raw material to obtain a superheated melt of the superalloy. The temperature measuring device used in this embodiment is an infrared thermometer with a temperature control accuracy better than 1° C., and a response rate of less than 10 ms.

Step five, cool down evenly. After repeated overheating of the superalloy raw material, the temperature is slowly lowered at a rate of 1.5-1.0°C/min, and the temperature is lowered to 5°C below the liquidus line of the melt, that is, 1395°C. At this time, a kilogram-level supercooled melt is obtained. Then it was poured at a pouring speed of 15.11kg/s into a mold shell with a preheating temperature of 1100°C, and finally the solid part in Example 2 was obtained. In this embodiment, the cooling rate of the superalloy melt is 1.5°C/min, and the liquidus of the melt is 1400°C.

Embodiment four

The specific implementation process of this example is as follows: this example is a preparation method of a 20Kg supercooled K417 superalloy melt.

Step one, the selection of induction power frequency. The conductor resistivity ρ and the conductor magnetic permeability μ are obtained according to the superalloy manual, and according to formula (1) and formula (2), the frequency of the intermediate frequency power supply is finally determined to be 1K Hz.

△H=d/n, (1)

In the formula, n is a constant. According to the formula (1), the current penetration depth △H of the intermediate frequency induction power supply is determined.

$\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}{<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 5030</span>}}{\mathrm{<span\; class="notranslate">\; \&Delta;H</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

In the formula: ρ is the resistivity of the conductor in Ω cm; μ is the magnetic permeability of the conductor in H/cm; f is the frequency of the current in Hz. Both the conductor resistivity ρ and the conductor magnetic permeability μ are obtained according to the superalloy handbook. According to the formula (2) determine the frequency f of the power supply.

According to the formula (1) and formula (2), the power frequency f of the melt is obtained.

Step two, the selection of the heating power of the power supply.

The heating power of the power supply is determined according to the formula (3).

y＝6.18exp(-x/17.32)+8.95 (3)

In the formula: y represents the heating power of the power supply, and the unit of heating power is kw; x represents the mass of the melt, and the unit is Kg; 6.18, 17.32 and 8.95 in the formula (3) are obtained by ANSYS software simulation calculation constant term. Obtain melts of different qualities to obtain supercooled melt power supply heating power as shown in Table 1:

Table 1: Power supply heating power corresponding to different quality melts

High temperature alloy/kg J _S /(10 ⁶ A/m ² ) P/kw 0.5 23.3 14.2

2 21.2 13.1 10 19.8 12.4 20 17.6 11 30 16 10

According to Table 1, the optimum power frequency of this embodiment is 11Kw.

Step three, preparation before melting. Put 20Kg of K417 superalloy raw material into a quartz crucible, pass argon protection at a vacuum of 10 ^-2 Pa, and start overheating when the pressure of argon is 0.5 Pa.

Step 4, cyclic superheating treatment. The superalloy raw material was heated to 1450°C under a 400Hz intermediate frequency power supply. When the superalloy raw material is heated to 1400°C and kept for 10 minutes, the temperature is lowered to 1400°C after the heat preservation is completed. Repeat the above process of heating-heating-cooling for a total of 5 times, and repeatedly overheat the superalloy raw material to obtain a superheated melt of the superalloy. The temperature measuring device used in this embodiment is an infrared thermometer with a temperature control accuracy better than 1° C., and a response rate of less than 10 ms.

Step five, cool down evenly. After the repeated superheating treatment of the superalloy raw material, the temperature is slowly lowered at a rate of 1.5-1.0°C/min, and the temperature is lowered to 5°C below the liquidus line of the melt, that is, 1335°C. At this time, a kilogram-level supercooled melt is obtained. Then it was poured at a pouring speed of 10.11kg/s into a mold shell with a preheating temperature of 1100°C, and finally the solid part in Example 2 was obtained. In this embodiment, the cooling rate of the superalloy melt is 1.5°C/min, and the liquidus of the melt is 1340°C.

Claims (1)

1. obtain a preparation method for feather weight superalloy subcooling films, it is characterized in that, concrete steps are:

Step one, the selection of induction power supply frequency; By conductor resistance rate ρ, conductor magnetic permeability μ, according to formula (1) and formula (2), determine supply frequency f;

△H＝d/n， (1)

In formula, n is constant; D is the diameter of heating cylinder melt, and unit is cm; The current penetration degree of depth △ H of medium frequency induction power supply is determined according to formula (1);

$f=\frac{\mathrm{\&rho;}}{\mathrm{\&mu;}}{\left(\frac{5030}{\mathrm{\&Delta;H}}\right)}^2---\left(2\right)$

In formula: ρ is the resistivity of conductor, unit Wei Ω ㎝; μ is the magnetic permeability of conductor, and unit is H/cm; F is the frequency of electric current, and unit is Hz; Described conductor resistance rate ρ, conductor magnetic permeability μ all check according to superalloy handbook;

Step 2, the selection of power supply heating power;

Power supply heating power is determined according to described formula (3);

y＝6.18exp(-x/17.32)+8.95 (3)

In formula: what y represented is power supply heating power, the unit of heating power is kw; The quality of what x represented is melt, unit is Kg; In formula (3) 6.18,17.32 and 8.95 are the constant term calculated by ANSYS software simulation;

Step 3, the preparation before melting; Bottom silica tube, paving covers the B that a layer thickness is 3mm ₂o ₃molten glass purification agent; Cleaned superalloy raw material is put into silica tube; The thick B of one deck 3mm is covered in described superalloy ingredient upper surface ₂o ₃molten glass purification agent, is fixed on silica tube on the ruhmkorff coil of medium frequency induction power supply;

Step 4, cyclical superheating process; Under intermediate frequency power supply, superalloy raw material be warming up to more than this superalloy liquidus line 100 DEG C and be incubated 5min; More than this superalloy liquidus line 50 DEG C is cooled to after insulation terminates; Repeat above-mentioned intensification-insulation-temperature-fall period totally 5 times, Overheating Treatment is repeatedly carried out to superalloy raw material, obtains superalloy superheated melt;

Step 5, uniform decrease in temperature; After Overheating Treatment terminates repeatedly to superalloy raw material, with the rate of temperature fall of 1.2 ~ 0.5 DEG C/min, superalloy raw material is obtained temperature and be down to below melt liquidus line 10 DEG C, obtain feather weight subcooling films.