CN114921706B - Modified nickel-based casting superalloy and preparation method thereof - Google Patents

Abstract

The disclosure provides a modified nickel-based cast superalloy and a preparation method thereof, wherein the modified nickel-based cast superalloy includes: a modified IN939 superalloy, and the components of the modified IN939 superalloy are expressed in mass percentages Including: C is 0.11‑0.16%, B is 0.006‑0.018%. The composition of the modified IN939 superalloy includes: Cr 22.24%, Co 18.73%, W 1.97%, Nb 0.89%, Ta 1.24%, Ti 3.66%, Al 1.90%, Mo 0.0063 %, P is 0.0015%, Mn is 0.0035%, C is 0.11‑0.16%, Zr is 0.006%, B is 0.006‑0.018%, Hf is 0.019%, V is 0.006%, Fe is 0.030%, impurities ≤0.01% , Ni is the balance, wherein, the percentage of each component is the mass percentage.

Description

Modified nickel-based casting superalloy and preparation method thereof

technical field

The disclosure belongs to the field of high-temperature alloy casting, and in particular relates to a modified nickel-based casting high-temperature alloy and a preparation method thereof.

Background technique

High-temperature alloy complex thin-walled castings are key components of advanced technical equipment for aerospace power systems, and their manufacturing capabilities and levels represent the capabilities and levels of a country's manufacturing technology to a certain extent. Due to the demand for higher performance, higher reliability and structural weight reduction, high-temperature alloy complex thin-walled castings represented by guides and casings are developing towards complex structures, thin-walled lightweight and precise dimensions, which are good for castings. The filling and organization are refined and have few or no defects, which put forward higher requirements. At the same time, with the continuous improvement of engine efficiency and speed, the service temperature of such castings continues to increase, requiring the use of alloys resistant to higher temperatures. However, when some nickel-based cast superalloys are manufactured into castings, due to the high degree of structural change of the castings, the casting performance and repair welding performance of nickel-based cast superalloys are poor, resulting in undercasting and shrinkage cavities when forming castings Defects such as these reduce the yield and performance of the casting, and affect the use of the casting.

Contents of the invention

In view of the above technical problems, the present disclosure provides a modified nickel-based cast superalloy and a preparation method, in order to at least partly solve the above technical problems.

In order to solve the above technical problems, as one aspect of the present disclosure, a modified nickel-based casting superalloy is provided, wherein the above-mentioned modified nickel-based casting superalloy includes: a modified IN939 superalloy;

The components of the modified IN939 superalloy include, by mass percentage: 0.11-0.16% of C and 0.006-0.018% of B.

According to an embodiment of the present disclosure, the composition of the above modified IN939 superalloy includes: Cr 22.24%, Co 18.73%, W 1.97%, Nb 0.89%, Ta 1.24%, Ti 3.66%, Al 1.90%, Mo 0.0063%, P 0.0015%, Mn 0.0035%, C 0.11-0.16%, Zr 0.006%, B 0.006-0.018%, Hf 0.019%, V 0.006%, Fe 0.030%, impurity≤0.01%, Ni is the balance, wherein, the percentage of each component is the mass percentage.

According to an embodiment of the present disclosure, in a fluidity test performed at a pouring temperature of 1450° C. and a mold shell temperature of 900° C., the streamline length of the above-mentioned modified IN939 superalloy includes: 369-546 mm.

According to an embodiment of the present disclosure, the liquidus temperature of the above-mentioned modified IN939 superalloy is greater than 1330°C; the working temperature of the modified IN939 superalloy includes: 0-870°C.

As another aspect of the present disclosure, a method for preparing a modified nickel-based cast superalloy is also provided, including:

Putting the additive and the unmodified nickel-based cast superalloy into a vacuum induction melting furnace for melting to obtain a modified nickel-based cast superalloy;

Wherein, the above-mentioned unmodified nickel-based casting superalloy includes: unmodified IN939 superalloy.

According to an embodiment of the present disclosure, the above additives include: boron particles and carbon powder.

According to an embodiment of the present disclosure, relative to 2000g of unmodified IN939 alloy, the dosage of the boron particles includes: 3-30g;

The dosage of the above carbon powder includes: 0-100g.

According to an embodiment of the present disclosure, the components in the above-mentioned unmodified IN939 superalloy include:

Cr is 22.24%, Co is 18.73%, W is 0.89%, Ta is 1.24%, Ti is 3.66%, Al is 1.9%, Mo is 0.0063%, P is 0.0015%, Mn is 0.0035%, C is 0.11%, Zr is 0.006%, B is 0.0042%, Hf is 0.019%, V is 0.006%, Fe is 0.030%, impurities≤0.01%, and the balance is Ni, wherein the percentages of each component are mass percentages.

According to an embodiment of the present disclosure, the vacuum pressure of the smelting includes: 6×10 ⁻² MPa; the temperature of the smelting includes: 1550-1600° C.

According to an embodiment of the present disclosure, the above smelting time includes: 10-30 minutes.

Based on the above technical solutions, it can be seen that the modified nickel-based cast superalloy and the preparation method provided by the present disclosure at least include one of the following beneficial effects:

(1) In the embodiments of the present disclosure, the nickel-based cast IN939 is a superalloy with a high degree of alloying and a wide solidification range, and the modified IN939 is prepared by regulating the content of boron and carbon components in the IN939 superalloy Superalloys, using the large atomic radius of boron and carbon atoms, make it difficult for the boron component of the modified IN939 superalloy to enter the octahedral gap of the face-centered cubic structure γ dendrite during the solidification process; and modification During the solidification process of the IN939 superalloy, boron and carbon atoms are continuously pushed out into the residual liquid, forming a boron-rich film at the front of the solid/liquid interface, and the thickness of the boron-rich film becomes thicker with the increase of boron and carbon content , the migration rate of boron atoms and carbon atoms is reduced, the growth rate of γ dendrites is slowed down, and the phenomenon of dendrite overlap occurs later, thereby improving the fluidity of the modified IN939 superalloy.

(2) In the embodiments of the present disclosure, boron and carbon, as surface active elements, have a positive adsorption effect and are easily adsorbed on the interface or surface, so that the concentration of boron and carbon elements on the surface of the melt is greater than the concentration inside the melt, The tension on the surface of the alloy melt is reduced, thereby improving the fluidity of the alloy.

(3) In the embodiment of the present disclosure, the content of boron and carbon components in the modified IN939 superalloy can strengthen the grain boundaries during the segregation of the grain boundaries. When the content of boron and carbon components exceeds its solubility, it will be along the Granular borides and carbides are precipitated at the grain boundaries, which can pin the grain boundaries and hinder the sliding deformation of the grain boundaries, thereby strengthening the grain boundaries and improving the tensile, durable and creep properties of the alloy.

(4) The present disclosure provides a relatively simple method to prepare the IN939 superalloy of modified nickel-based casting. By regulating the boron and carbon component contents in the unmodified IN939 superalloy, the Under the premise of performance, improve the flow performance of the modified IN939 superalloy.

Description of drawings

Fig. 1A is the physical picture of the unmodified IN939 superalloy in comparative example 1 of the present disclosure;

1B-F are physical diagrams of the influence of different contents of carbon and boron components on the fluidity of the modified IN939 superalloy in the embodiments of the present disclosure;

Fig. 2 is an effect diagram of the effect of different contents of boron and carbon components in Examples 1-5 of the present disclosure on the surface tension of the prepared modified IN939 superalloy at different temperatures.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present disclosure clearer, the present disclosure will be further described in detail below in conjunction with specific embodiments.

Based on the existing nickel-based casting superalloys, there are defects such as undercasting and shrinkage cavities in castings, which reduce the yield and performance of castings. The forming ability of castings is closely related to casting technology and alloy materials, and the fluidity of alloys In theory, it is directly related to the filling capacity of the metal. At present, the casting process with higher pouring temperature and mold shell temperature is often used in the production process to improve the fluidity of the alloy, but this method will increase the grain structure of the alloy after solidification and reduce the mechanical properties of the casting. Therefore, in the casting process, in addition to considering the characteristics of the alloy itself, how to improve the fluidity of the alloy without reducing the mechanical properties of the casting (alloy), how to obtain a well-formed and complete casting and reduce the occurrence of defects, and can Indirect refinement of grains and improvement of comprehensive performance of castings are of great significance to the forming quality of large, complex and thin-walled castings. However, in alloy systems with different compositions, the composition of different elements and the mechanism of action of elements on the alloy are different. For specific alloy systems, it is necessary to explore and clarify the influence of its components on its structure and properties in order to facilitate practical applications. Therefore, this disclosure explores the IN939 superalloy of nickel-based casting, and proposes a method of adjusting the composition of the nickel-based superalloy to improve the flow of the superalloy without changing the mechanical properties of the nickel-based casting superalloy. performance to meet the needs of practical applications.

The present disclosure provides a modified nickel-based casting superalloy, wherein the modified nickel-based casting superalloy includes: a modified IN939 superalloy, and the components of the modified IN939 superalloy include: C 0.11-0.16% and B 0.006-0.018%.

According to an embodiment of the present disclosure, the composition of the modified IN939 superalloy includes: Cr 22.24%, Co 18.73%, W 1.97%, Nb 0.89%, Ta 1.24%, Ti 3.66%, Al 1.90%, Mo 0.0063%, P 0.0015%, Mn 0.0035%, C 0.11-0.16%, Zr 0.006%, B 0.006-0.018%, Hf 0.019%, V 0.006%, Fe 0.030 %, impurity≤0.01%, Ni is the balance, wherein, the percentage of each component is the mass percentage.

According to an embodiment of the present disclosure, the content of component C is 0.11-0.16%, among which, 0.11%, 0.15%, 0.16%, etc. are optional; the content of component B is 0.006-0.018%, among which, 0.006% is optional %, 0.01%, 0.014%, 0.018%, etc.

According to an embodiment of the present disclosure, in the fluidity test conducted under the conditions of pouring temperature of 1450° C. and mold shell temperature of 900° C., the streamline length of the modified IN939 superalloy includes: 369-546 mm.

According to an embodiment of the present disclosure, the liquidus temperature of the modified IN939 superalloy is greater than 1330°C, wherein the liquidus temperature range includes 1330-1341°C, more preferably 1340-1341°C; the modified IN939 superalloy is suitable Working temperatures used include 0-870°C.

Embodiments of the present disclosure also provide a method for preparing a modified nickel-based cast superalloy, including: putting additives and unmodified nickel-based cast superalloy into a vacuum induction melting furnace for melting to obtain a modified Nickel-based casting superalloys, wherein the unmodified nickel-based casting superalloys include: unmodified IN939 superalloy.

According to an embodiment of the present disclosure, the additive includes boron particles and carbon powder.

According to an embodiment of the present disclosure, relative to 2000g of unmodified IN939 alloy, the amount of boron particles includes: 3-30g, wherein the amount of boron particles can be 3, 5, 10, 15, 20, 25, 30g, etc. ;

Relative to 2000g of unmodified IN939 alloy, the amount of carbon powder includes: 0-100g, wherein, can be 0, 20, 40, 60, 80, 100g, etc.

According to an embodiment of the present disclosure, the components in the unmodified IN939 superalloy include:

Cr is 22.24%, Co is 18.73%, W is 0.89%, Ta is 1.24%, Ti is 3.66%, Al is 1.9%, Mo is 0.0063%, P is 0.0015%, Mn is 0.0035%, C is 0.11%, Zr is 0.006%, B is 0.0042%, Hf is 0.019%, V is 0.006%, Fe is 0.030%, impurities≤0.01%, and the balance is Ni, wherein the percentages of each component are mass percentages.

According to an embodiment of the present disclosure, the vacuum pressure for smelting includes: 6×10 ⁻² MPa.

According to an embodiment of the present disclosure, the smelting temperature includes: 1550-1600°C, wherein, 1550, 1575, 1600°C can be selected.

According to an embodiment of the present disclosure, the smelting time includes: 10-30 minutes, wherein, 10, 15, 20, 25, 30 minutes, etc. can be selected.

In order to make the purpose, technical solutions and advantages of the present disclosure clearer, the technical solutions and principles of the present disclosure will be further explained below through specific embodiments in conjunction with the accompanying drawings. It should be noted that the following specific embodiments are only for illustration, and the protection scope of the present disclosure is not limited thereto.

This disclosure selects a nickel-based casting unmodified IN939 superalloy to explore, and explores how to improve the flowability of the IN939 superalloy without affecting the mechanical properties of the IN939 superalloy by regulating the content of boron and carbon components . It should be noted that the unmodified IN939 superalloy used in the present disclosure is only for illustrating that the method of the present disclosure can realize the improvement of the fluidity of the IN939 superalloy by regulating and controlling the content of boron and carbon components in the unmodified IN939 superalloy. Improvement, for the unmodified IN939 superalloy of nickel-based casting with other component content, the fluidity performance of the IN939 superalloy can also be improved by adjusting the content of carbon and boron components, but the scope of protection claimed by the present disclosure is not limited thereto .

The performance testing method of the IN939 superalloy involved in the embodiments of the present disclosure is as follows:

Flow performance test:

After heating the spiral fluid formwork with a spiral segment thickness of 3 mm and a height of 10 mm to 900° C. and keeping it warm for 4 hours. The obtained IN939 superalloys with different boron and carbon content were placed in a vacuum induction melting furnace for melting. After the IN939 superalloys were completely melted, they were kept at 1550°C for 2 minutes. , casting the IN939 superalloy liquid into the preheated spiral fluidity mold shell at a pouring speed of 0.5kg/s. After the alloy liquid is poured, the mold shell is naturally cooled to room temperature, the spiral fluidity model is knocked open, the cooled spiral IN939 superalloy sample is taken out, and the streamline length is measured to determine the fluidity of the superalloy. The above-mentioned IN939 superalloy includes: modified IN939 superalloy and unmodified IN939 superalloy.

The heat treatment process of IN939 superalloy sample test is as follows:

The obtained IN939 superalloy sample is placed in a heat treatment furnace for 4-step heat treatment such as solid solution and aging, wherein the specific processes and parameters involved in the heat treatment process include:

a. Solution heat treatment: heat preservation at 1160°C for 4 hours, then quickly cool to room temperature with air;

b. Aging heat treatment: first keep warm at 1000°C for 6 hours, then quickly cool with air to room temperature; keep warm at 900°C for 24 hours and then cool with air; finally keep warm at 700°C for 16 hours, then quickly cool with air to room temperature.

Finally, the IN939 superalloy sample after the above heat treatment was subjected to a room temperature tensile test using a universal tensile testing machine under the condition of a strain rate of 2×10 ^-3 /s, and the tensile strength and yield strength of the IN939 superalloy were measured. and elongation.

Example

In an embodiment of the present disclosure, a method for preparing a modified nickel-based casting IN939 superalloy, the specific steps involved are as follows:

S1. Ingredients: Take carbon powder, boron particles and unmodified IN939 superalloy, and weigh the ingredients according to the content of the designed boron and carbon components in the modified IN939 superalloy;

S2. Vacuum smelting: put the unmodified IN939 superalloy into a vacuum induction melting furnace for smelting. When the unmodified IN939 superalloy is completely melted, the boron required for 2000g of unmodified IN939 alloy The amount of particles includes: 3-30g and the amount of required carbon powder includes: 0-100g to weigh the ingredients, then add the ingredients to the crucible through the feeding bin of the vacuum induction melting furnace, and repeatedly melt 5 times, Reduce macro-segregation and make the added boron and carbon components evenly distributed in the modified IN939 superalloy, so as to obtain different boron and carbon component contents to prepare modified IN939 superalloy samples.

The smelting conditions involved in the present disclosure include: a. a vacuum state of 6×10 ^-2 MPa; b. a smelting temperature of 1550° C. to 1600° C.; c. electromagnetic stirring used in the smelting process; d. a smelting time of 15 minutes.

Example 1

Embodiment 1 is the modified IN939 superalloy composed of 0.11% C content, 0.006% B content and other component contents, wherein, the formula of the modified IN939 superalloy is as shown in Table 1, accompanying drawing The label in is 1.

Table 1

Cr(%) Co(%) W(%) Nb(%) Ta(%) Ti(%) Al(%) 22.24 18.73 1.97 0.89 1.24 3.66 1.90 Mo(%) P(%) Mn(%) C(%) Zr(%) B(%) Ni (%) 0.0063 0.0015 0.0035 0.11 0.006 0.006 margin Hf(%) V(%) Fe(%) Impurities (%) 0.019 0.006 0.030 ≤0.01

Example 2

Embodiment 2 is a modified IN939 superalloy composed of 0.11% C content, 0.01% B content and other component contents, wherein the formula of the modified IN939 superalloy is as shown in Table 2, accompanying drawing The label in is 2.

Table 2

Cr(%) Co(%) W(%) Nb(%) Ta(%) Ti(%) Al(%) 22.24 18.73 1.97 0.89 1.24 3.66 1.90 Mo(%) P(%) Mn(%) C(%) Zr(%) B(%) Ni (%) 0.0063 0.0015 0.0035 0.11 0.006 0.01 margin Hf(%) V(%) Fe(%) Impurities (%) 0.019 0.006 0.030 ≤0.01

Example 3

Embodiment 3 is the modified IN939 superalloy composed of C content of 0.11%, B content of 0.014% and other component contents, wherein, the formula of the modified IN939 superalloy is shown in Table 3, accompanying drawing The label in is 3.

table 3

Cr(%) Co(%) W(%) Nb(%) Ta(%) Ti(%) Al(%) 22.24 18.73 1.97 0.89 1.24 3.66 1.90 Mo(%) P(%) Mn(%) C(%) Zr(%) B(%) Ni (%) 0.0063 0.0015 0.0035 0.11 0.006 0.014 margin Hf(%) V(%) Fe(%) Impurities (%) 0.019 0.006 0.030 ≤0.01

Example 4

Embodiment 4 is the modified IN939 superalloy composed of C content of 0.11%, B content of 0.018% and other component contents, wherein, the formula of the modified IN939 superalloy is shown in Table 4, accompanying drawing The number in is 4.

Table 4

Cr(%) Co(%) W(%) Nb(%) Ta(%) Ti(%) Al(%) 22.24 18.73 1.97 0.89 1.24 3.66 1.90 Mo(%) P(%) Mn(%) C(%) Zr(%) B(%) Ni (%) 0.0063 0.0015 0.0035 0.11 0.006 0.018 margin Hf(%) V(%) Fe(%) Impurities (%) 0.019 0.006 0.030 ≤0.01

Example 5

Embodiment 5 is the modified IN939 superalloy composed of C content of 0.16%, B content of 0.014% and other component contents, wherein, the formula of the modified IN939 superalloy is shown in Table 5, accompanying drawing The number in is 5.

table 5

Cr(%) Co(%) W(%) Nb(%) Ta(%) Ti(%) Al(%) 22.24 18.73 1.97 0.89 1.24 3.66 1.90 Mo(%) P(%) Mn(%) C(%) Zr(%) B(%) Ni (%) 0.0063 0.0015 0.0035 0.16 0.006 0.014 margin Hf(%) V(%) Fe(%) Impurities (%) 0.019 0.006 0.030 ≤0.01

comparative example

Comparative example 1

The preparation method of the unmodified IN939 superalloy in Comparative Example 1 is the same as that in the example, the only difference is that no additional boron particles and carbon powder are added.

The C content in the unmodified IN939 superalloy in Comparative Example 1 is 0.11%, and the B content is 0.0042%. The composition of other contents in the unmodified IN939 superalloy is shown in Table 6, where the percentages are mass percentages .

Table 6

Cr(%) Co(%) W(%) Nb(%) Ta(%) Ti(%) Al(%) 22.24 18.73 1.97 0.89 1.24 3.66 1.90 Mo(%) P(%) Mn(%) C(%) Zr(%) B(%) Ni(%) 0.0063 0.0015 0.0035 0.11 0.006 0.0042 margin Hf(%) V(%) Fe(%) Impurities (%) 0.019 0.006 0.030 ≤0.01

Fig. 1A is the physical figure of the unmodified IN939 superalloy in Comparative Example 1 of the present disclosure; Fig. 1B-F is the physical object of the influence of different contents of carbon and boron components on the fluidity of the modified IN939 superalloy in the embodiments of the present disclosure picture.

With the IN939 superalloy in the above-mentioned examples and comparative examples, the fluidity and tensile properties of the IN939 superalloy were tested by using a spiral fluidity test model at a casting temperature of 1450° C. and a mold shell temperature of 900° C. The streamline length of the liquid superalloy when solidified in the model is measured to characterize its fluidity, wherein, the IN939 superalloy includes: modified IN939 superalloy and unmodified IN939 superalloy.

Table 7 shows the flow performance test results of the examples of the present disclosure and comparative examples of the IN939 superalloy.

Table 7

As can be seen from Table 7, using the method provided by the present disclosure, the modified IN939 superalloy is prepared by increasing the content of boron and carbon elements. Compared with the unmodified IN939 superalloy, the mechanical properties of the superalloy are not reduced. , when the mass percentages of boron and carbon components are 0.006-0.018% and 0.11-0.16% respectively, the flow properties of the modified IN939 superalloy can be increased by 21-79%, especially when the content of boron and carbon components When it is 0.14% and 0.16%, the fluidity of the prepared modified IN939 superalloy is 79% higher than that of the unmodified IN939 superalloy.

Comparative example 2

Comparative example 2 is a modified IN939 superalloy consisting of C content of 0.18%, B content of 0.20% and other components. The formula of the modified IN939 superalloy is shown in Table 8.

Table 8

Cr(%) Co(%) W(%) Nb(%) Ta(%) Ti(%) Al(%) 22.24 18.73 1.97 0.89 1.24 3.66 1.90 Mo(%) P(%) Mn(%) C(%) Zr(%) B(%) Ni (%) 0.0063 0.0015 0.0035 0.18 0.006 0.20 margin Hf(%) V(%) Fe(%) Impurities (%) 0.019 0.006 0.030 ≤0.01

Through the DSC experiment (differential scanning calorimetry) and JMatPro software calculation of the modified IN939 superalloy prepared by the components in Table 8, the data related to the solidification temperature range of the modified IN939 superalloy were obtained. Experimental results show that the solidification temperature range in Comparative Example 2 is about 10° C. larger than that in the embodiment of the present disclosure. The larger the solidification range of the superalloy, the worse the fluidity. Therefore, for the modified IN939 superalloy, when the carbon and boron content ranges provided by the disclosure are exceeded, its fluidity becomes poor, wherein the solidification temperature range in Examples 1-5 of the disclosure is 92-98°C, The solidification temperature range in Comparative Example 2 is 108°C.

At the same time, due to the further increase in the content of carbon and boron components, it is easy to form low-melting point phases such as borides, which reduces the initial melting temperature by about 10°C compared with the alloys in the scope of the embodiments of the present disclosure, resulting in the hot workability and service temperature of the alloy Reduce, wherein, the range of the initial melting temperature of Examples 1-5 of the present disclosure is 1223-1216°C, and the initial melting temperature in Comparative Example 2 is 1206°C.

By changing the content of boron and carbon components in the IN939 superalloy, the fluidity of the IN939 superalloy can be changed mainly as follows:

(1) IN939 superalloy is a nickel-based casting superalloy, which belongs to the alloy with a wide crystallization temperature range. For superalloys with a large solidification range, the solidification process is slow, and it is easy to form a large number of dendrites. The dendrites grow and connect into a network, and then The flow of the alloy liquid is hindered, so that the liquid alloy cannot heal the torn liquid film between the dendrite grain boundaries, forming solidification cracks. In the embodiment of the present disclosure, the flow stop is due to the growth of dendrites in the solidification process of the IN939 superalloy, and as the viscosity of the alloy liquid increases and the flow rate slows down, when the dendrites in the IN939 superalloy overlap each other When a continuous network is formed directly and the pressure of the alloy liquid cannot overcome the resistance of the network at this time, the flow of the alloy liquid stops. Therefore, delaying the dendrite lapping of IN939 superalloy can improve the fluidity of IN939 superalloy, and the speed of dendrite lapping of IN939 superalloy is mainly affected by the growth rate of γ dendrites. According to the theory of crystal growth, the growth rate of γ dendrites in the alloy can be expressed by the following formula:

V＝δ(R _S - R _l ) (1)

In formula (1), δ is the typical interatomic distance, R _s is the rate of atomic transition from liquid phase to solid phase, and R _l is the rate of atomic transition rate from solid phase to liquid phase.

During the solidification process of superalloys, since it is difficult for boron and carbon atoms to enter the octahedral gaps of the face-centered cubic structure γ dendrites during the solidification process, boron and carbon atoms are continuously squeezed out to the residual In the liquid, a boron-rich film is formed at the front of the solid/liquid interface, and as the content of boron and carbon components increases, the film thickness of the boron-rich film gradually becomes thicker, thereby reducing the rate R _s of atoms transitioning from the liquid phase to the solid phase and the transition rate R _l from the solid phase to the liquid phase, the growth rate V of the γ dendrites in the alloy decreases from 0.09 to 0.083, which makes the phenomenon of γ dendrite overlap appear later, thereby improving the flow of the superalloy sex.

In addition, when the alloy is solidified, the smaller the undercooling of the alloy, the smaller the growth rate of γ dendrites. The degree of undercooling of the modified IN939 superalloy in the examples of the present disclosure decreases from 11°C to 3°C with the increase of boron and carbon content, so that the growth rate of γ dendrites decreases, which in turn makes γ dendrites The grain lapping phenomenon occurs later, which improves the fluidity of the alloy.

(2) Surface tension also has an important influence on the flow process of superalloy liquid. In the flowing process of the IN939 superalloy liquid of the present disclosure, the surface tension generated is the pressure pointing to the inside of the alloy melt, which promotes the contraction of the surface of the alloy melt. The greater the surface tension, the greater the pressure generated, which affects the fluidity of the superalloy. The greater the resistance, the lower the fluidity of the superalloy. The surface tension of the alloy to the melt can be expressed by the following formula:

In formula (2), Γ is the mass of solute adsorbed per unit liquid metal surface area than the interior (mol/m ^-3 ); R is the Boltzmann constant; T is the thermodynamic temperature (K); C _i is the solute concentration, dσ/(d _Ci ) characterizes the surface tension of the alloy.

As surface active elements, boron and carbon have positive adsorption and can be enriched in the residual liquid phase. Therefore, it is easy to be adsorbed on the interface or surface, causing the concentration of boron and carbon on the surface of the alloy melt to be greater than the concentration inside the melt, so that Γ is positive and -C _i /RT is negative, then dσ/(d _Ci ) is negative.

Fig. 2 is an effect diagram of the effect of different contents of boron and carbon components in Examples 1-5 of the present disclosure on the surface tension of the prepared modified IN939 superalloy at different temperatures.

As shown in Figure 2, JMatPro software is used to explore the influence of different contents of boron and carbon components in the examples on the surface tension of the modified IN939 superalloy prepared at different temperatures. When the content of boron and carbon in the alloy increases, That is to say, the increase of solute concentration C _i reduces the surface tension of the alloy melt, which reduces the flow resistance in the cavity, thereby improving the fluidity of the modified IN939 superalloy.

Table 9 is the test results of the tensile properties of the IN939 superalloy modified in Examples 2 and 5 of the present disclosure and the IN939 superalloy in Comparative Example 1.

Table 9

Alloy type Tensile strength (MPa) Yield strength (MPa) Elongation (%) Comparative example 1 810.5 653.8 3.41 Example 2 916.5 711.6 5.75 Example 5 900.9 827.5 5.69

It can be seen from Table 9 that an appropriate increase in the content of boron components and boron and carbon components in IN939 superalloy can effectively improve the tensile properties, creep and durability properties of the alloy. The main reason is that boron and carbon components in nickel-based superalloys tend to fill grain boundary defects by changing the concentration of valence electrons in the grain boundary region and forming strong metal bonds, which can hinder the migration and diffusion of grain boundaries , improve the grain boundary binding force, reduce the formation rate of grain boundary voids in the enduring process, thereby improving the tensile, creep and enduring properties of the alloy. In addition, after the segregation of boron and carbon at the grain boundary exceeds its solubility, borides and carbides will be precipitated along the grain boundary, and the granular borides and carbides precipitated along the grain boundary can pin the grain boundary and hinder the grain boundary. The slip deformation can strengthen the grain boundary, improve the tensile and durable and creep properties of the alloy. However, when the content of boron and carbon components in the IN939 superalloy is too much, the borides or carbides in the alloy will be precipitated in the form of blocks or lamellar sheets, and there will be a problem of difficulty in deformation during the permanent fracture of the alloy, which will easily lead to micro Pores form and connect, deteriorating the tensile and durable properties of the alloy.

Therefore, considering the influence of boron and carbon components on the comprehensive properties of the modified IN939 superalloy, by controlling the content of boron and carbon components in the range of 0.006-0.018% and 0.11-0.16%, respectively, it can be achieved without reducing the Under the premise of mechanical properties, the flow properties of the modified IN939 superalloy are improved to meet the needs of advanced aero-engine castings.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present disclosure in detail. It should be understood that the above descriptions are only specific embodiments of the present disclosure, and are not intended to limit the present disclosure. Within the spirit and principles of the present disclosure, any modifications, equivalent replacements, improvements, etc., shall be included in the protection scope of the present disclosure.

Claims (6)

1. A modified nickel-base cast superalloy, wherein the modified nickel-base cast superalloy is a modified IN939 superalloy;

the modified IN939 superalloy comprises the following components IN percentage by mass: 0.16% C, 0.014% B or 0.11% C, 0.018% B; and

22.24% Cr, 18.73% Co, 1.97% W, 0.89% Nb, 1.24% Ta, 3.66% Ti, 1.90% Al, 0.0063% Mo, 0.0015% P, 0.0035% Mn, 0.006% Zr, 0.019% Hf, 0.006% V, 0.030% Fe, less than or equal to 0.01% impurity, and the balance Ni;

IN the flowability test at 1450℃and 900℃in the form, the modified IN939 superalloy with 0.16% C and 0.014% B had a streamline length of 546mm or the modified IN939 superalloy with 0.11% C and 0.018% B had a streamline length of 387mm.

2. The superalloy of claim 1, wherein the modified IN939 superalloy has a liquidus temperature greater than 1330 ℃;

the operating temperatures for the modified IN939 superalloy include: 0-870 ℃.

3. A method of preparing a modified nickel-base cast superalloy comprising:

placing the additive and the unmodified nickel-based casting superalloy into a vacuum induction melting furnace for melting to obtain the modified nickel-based casting superalloy;

wherein the unmodified nickel-base casting superalloy is: unmodified IN939 superalloy; the modified nickel-based casting superalloy is as follows: an IN939 superalloy, the modified IN939 superalloy comprising, IN mass percent: 0.16% C, 0.014% B or 0.11% C, 0.018% B; and

22.24% Cr, 18.73% Co, 1.97% W, 0.89% Nb, 1.24% Ta, 3.66% Ti, 1.90% Al, 0.0063% Mo, 0.0015% P, 0.0035% Mn, 0.006% Zr, 0.019% Hf, 0.006% V, 0.030% Fe, less than or equal to 0.01% impurity, and the balance Ni;

the additive comprises: boron particles and carbon powder, wherein the amounts of boron particles relative to 2000g of unmodified IN939 alloy comprise: 3-30g, wherein the dosage of the carbon powder comprises: 0-100g.

4. The method of claim 3, wherein the components IN the unmodified IN939 superalloy comprise:

22.24% of Cr, 18.73% of W, 0.89% of Ta, 1.24% of Ti, 1.9% of Al, 0.0063% of Mo, 0.0015% of P, 0.0035% of Mn, 0.11% of C, 0.006% of Zr, 0.0042% of B, 0.019% of Hf, 0.006% of V, 0.030% of Fe, less than or equal to 0.01% of impurities and the balance of Ni, wherein the percentages of the components are in mass percent.

5. The method of claim 3, wherein the vacuum pressure of smelting comprises: 6X 10 ^-2 MPa；

The smelting temperature includes: 1550-1600 ℃.

6. The method of claim 3, wherein the time of smelting comprises: 10-30 min.