CN114921706A - Modified nickel-based casting high-temperature alloy and preparation method thereof - Google Patents

Abstract

The present disclosure provides a modified nickel-based cast superalloy and a preparation method, wherein the modified nickel-based cast superalloy includes: modified IN939 superalloy, and the components of the modified IN939 superalloy are in mass percent Including: C is 0.11‑0.16%, B is 0.006‑0.018%. The composition of the modified IN939 superalloy includes: Cr is 22.24%, Co is 18.73%, W is 1.97%, Nb is 0.89%, Ta is 1.24%, Ti is 3.66%, Al is 1.90%, Mo is 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 remainder, and the percentage of each component is the mass percentage.

Description

Modified nickel-based casting superalloy and preparation method thereof

technical field

The present disclosure belongs to the field of superalloy casting, and in particular relates to a modified nickel-based casting superalloy and a preparation method.

Background technique

Superalloy complex thin-walled castings are key components of advanced technical equipment for aerospace power systems, and their manufacturing capabilities and levels represent to a certain extent the capabilities and levels of a country's manufacturing technology. Due to the demand for higher performance, higher reliability and structural weight reduction, superalloy complex thin-walled castings represented by guides, casings, etc. are developing towards complex structure, thin-walled lightweight and dimensional accuracy, which are good for castings. Filling, organization are refined and less or no defects put forward higher requirements. At the same time, with the continuous improvement of engine efficiency and rotation speed, the service temperature of such castings continues to increase, and alloys with higher temperature resistance are required. However, some nickel-based cast superalloys have poor casting performance and repair welding performance due to the high degree of structural change of the castings when manufacturing castings, resulting in under-casting and shrinkage cavities when forming castings. and other defects, reducing the yield and performance of the casting, and affecting the use of the casting.

SUMMARY OF THE INVENTION

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

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

The components of the above modified IN939 superalloy in terms of mass percentage include: C is 0.11-0.16%, B is 0.006-0.018%.

According to an embodiment of the present disclosure, the composition of the above-mentioned modified IN939 superalloy includes: Cr is 22.24%, Co is 18.73%, W is 1.97%, Nb is 0.89%, Ta is 1.24%, Ti is 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%, impurities≤0.01%, Ni is the balance, and the percentage of each component is the mass percentage.

According to an embodiment of the present disclosure, in the fluidity test performed under the conditions of 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 the embodiment of the present disclosure, the liquidus temperature of the above-mentioned modified IN939 superalloy is greater than 1330°C; the working temperature used by the modified IN939 superalloy includes: 0-870°C.

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

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

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

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

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

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

According to embodiments 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 percentage of each component is mass percentage.

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

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

Based on the above technical solutions, it can be known that a modified nickel-based casting superalloy and a preparation method provided by the present disclosure have at least 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 interval, and the modified IN939 is prepared by regulating the content of boron and carbon components in the IN939 superalloy. Superalloys, using boron and carbon atoms with large atomic radii, 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 expelled into the residual liquid, and a boron-rich film is formed at the front of the solid/liquid interface, and the thickness of the boron-rich film increases with the increase of boron and carbon content. , reducing the migration rate of boron atoms and carbon atoms, so that the growth rate of γ dendrites is slowed down, and the dendrite overlap phenomenon appears 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 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, when the content of boron and carbon components in the modified IN939 superalloy is segregated at the grain boundary, the grain boundary can be strengthened. When the content of boron and carbon components exceeds its solubility, it will be Granular borides and carbides are precipitated at the grain boundaries, which can pin the grain boundaries and hinder the slip deformation of the grain boundaries, thereby strengthening the grain boundaries and improving the tensile, durability and creep properties of the alloy.

(4) The present disclosure provides a relatively simple method to prepare a modified nickel-based cast IN939 superalloy. By regulating the content of boron and carbon components in the unmodified IN939 superalloy, the mechanical On the premise of performance, improve the flow properties of modified IN939 superalloy.

Description of drawings

FIG. 1A is a physical diagram of unmodified IN939 superalloy in Comparative Example 1 of the present disclosure;

1B-F are physical graphs of the effect of different levels of carbon and boron components on the fluidity of modified IN939 superalloys in embodiments of the present disclosure;

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

Detailed ways

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

The existing nickel-based casting superalloys have defects such as under-casting and shrinkage cavities during casting, which reduce the yield and performance of the castings. The forming ability of the castings is closely related to the casting process and alloy materials. The fluidity of the alloy In theory, it is directly related to the filling ability 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 size of the alloy after solidification and reduce the mechanical properties of the casting. Therefore, in addition to considering the characteristics of the alloy itself during the casting process, how to improve the fluidity of the alloy without reducing the mechanical properties of the casting (alloy), obtain a well-formed and complete casting and reduce the generation of defects, and can Indirectly refining grains and improving the comprehensive performance of castings are of great significance to the forming quality of large and complex thin-walled castings. However, the composition of different elements and the mechanism of action of elements on the alloy are different in alloy systems with different compositions. For specific alloy systems, it is necessary to explore and clarify the influence of their components on their microstructure and properties in order to facilitate practical applications. Therefore, the present disclosure explores the IN939 superalloy for nickel-based casting, and proposes a method by adjusting the composition of the nickel-based superalloy in order 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 in mass percentages include: C It is 0.11-0.16%, and B is 0.006-0.018%.

According to an embodiment of the present disclosure, the composition of the modified IN939 superalloy includes: Cr is 22.24%, Co is 18.73%, W is 1.97%, Nb is 0.89%, Ta is 1.24%, Ti is 3.66%, Al is 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 %, impurities≤0.01%, Ni is the balance, and the percentage of each component is the mass percentage.

According to the embodiments of the present disclosure, the content of component C is 0.11-0.16%, wherein the content of component B is 0.11%, 0.15%, 0.16%, etc., and the content of component B is 0.006-0.018%, and the content of component B is 0.006% %, 0.01%, 0.014%, 0.018%, etc.

According to an embodiment of the present disclosure, in the fluidity test conducted under the conditions of a pouring temperature of 1450° C. and a 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 for Operating temperatures used include 0-870°C.

Embodiments of the present disclosure also provide a method for preparing a modified nickel-based casting superalloy, comprising: placing an additive and an unmodified nickel-based casting superalloy in a vacuum induction melting furnace for melting to obtain a modified The nickel-based casting superalloy, wherein the unmodified nickel-based casting superalloy comprises: unmodified IN939 superalloy.

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

According to the embodiments 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 selected as 3, 5, 10, 15, 20, 25, 30g, etc. ;

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

According to embodiments 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 percentage of each component is mass percentage.

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

According to the embodiment of the present disclosure, the temperature of smelting includes: 1550-1600°C, wherein, 1550, 1575, and 1600°C are optional.

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

In order to make the objectives, technical solutions and advantages of the present disclosure more clear and definite, the technical solutions and principles of the present disclosure will be further explained below through specific embodiments and 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.

The present disclosure selects a nickel-based cast unmodified IN939 superalloy for research, and explores how to improve the flow properties of the IN939 superalloy without affecting the mechanical properties of the IN939 superalloy by adjusting the content of boron and carbon components . It should be noted that the unmodified IN939 superalloy selected in the present disclosure is only to illustrate that the method of the present disclosure can realize the improvement of the flow properties of the IN939 superalloy by regulating the content of boron and carbon components in the unmodified IN939 superalloy. Improvement, for the unmodified IN939 superalloy cast by other components, the flow properties of the IN939 superalloy can also be improved by adjusting the content of carbon and boron components, but the scope of protection of the present disclosure is not limited to this. .

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

Flow performance test:

The spiral-type flowable mold shell with a spiral section thickness of 3 mm and a height of 10 mm was heated to 900° C. and kept for 4 hours. The obtained IN939 superalloy with different contents of boron and carbon components is placed in a vacuum induction melting furnace for melting. After the IN939 superalloy is completely melted, it is kept at 1550 ° C for 2 minutes, and when the obtained IN939 superalloy liquid is cooled to 1450 ° C , pour the IN939 superalloy liquid into the preheated spiral fluidity mold at the pouring speed of 0.5kg/s. The mold shell after the alloy liquid was poured was naturally cooled to room temperature, the spiral fluidity model was knocked out, the cooled spiral IN939 superalloy sample was taken out, and its streamline length was measured to determine the fluidity of the superalloy. The IN939 superalloys described include: modified IN939 superalloys and unmodified IN939 superalloys.

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

The obtained IN939 superalloy sample is placed in a heat treatment furnace for 4-step heat treatment including solution and aging. The specific processes and parameters involved in the heat treatment process include:

a. Solution heat treatment: keep at 1160℃ for 4h, then quickly cool to room temperature with air;

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

Finally, under the condition of strain rate of 2×10 ^-3 /s, the IN939 superalloy sample after heat treatment was subjected to a room temperature tensile test using a universal tensile testing machine, 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 designed content of boron and carbon components in the modified IN939 superalloy;

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

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

Example 1

Embodiment 1 is a modified IN939 superalloy with a C content of 0.11%, a B content of 0.006% and other components, wherein the modified IN939 superalloy has a formula as shown in Table 1, and the accompanying drawings 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 with a C content of 0.11%, a B content of 0.01% and other components, wherein the modified IN939 superalloy has a formula as shown in Table 2, and the accompanying drawings 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 a modified IN939 superalloy with a C content of 0.11%, a B content of 0.014% and other components, wherein the modified IN939 superalloy has a formula as shown in Table 3, and the accompanying drawings 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

Example 4 is a modified IN939 superalloy with a C content of 0.11%, a B content of 0.018% and other components, wherein the modified IN939 superalloy has a formula as shown in Table 4, and the accompanying drawings in the label 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 a modified IN939 superalloy with a C content of 0.16%, a B content of 0.014% and other components, wherein the modified IN939 superalloy has a formula as shown in Table 5, and the accompanying drawings The label 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 ratio

Comparative Example 1

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

In Comparative Example 1, the C content in the unmodified IN939 superalloy is 0.11% and the B content is 0.0042%, and the component compositions of other contents in the unmodified IN939 superalloy are 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 a physical image of the unmodified IN939 superalloy in Comparative Example 1 of the present disclosure; FIGS. 1B-F are physical images of the influence of different contents of carbon and boron components on the fluidity of the modified IN939 superalloy in the embodiment of the present disclosure. picture.

The fluidity and tensile properties of the IN939 superalloy in the above examples and comparative examples were tested by using a spiral fluidity test model under the conditions of 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 determined to characterize its fluidity, wherein the IN939 superalloy includes: modified IN939 superalloy and unmodified IN939 superalloy.

Table 7 shows the test results of the flow properties of the IN939 superalloy of the embodiment of the present disclosure and the comparative example.

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 improved by 21-79%, especially when the content of boron and carbon components At 0.14% and 0.16%, respectively, the fluidity of the prepared modified IN939 superalloy was 79% higher than that of the unmodified IN939 superalloy.

Comparative Example 2

Comparative Example 2 is a modified IN939 superalloy composed of a C content of 0.18%, a 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

By performing DSC experiments (differential scanning calorimetry) and JMatPro software calculation on the modified IN939 superalloy prepared with the components in Table 8, the data related to the solidification temperature interval of the modified IN939 superalloy were obtained. The experimental results show that the solidification temperature range in Comparative Example 2 is increased by about 10° C. compared with the solidification temperature range in the embodiments of the present disclosure. The larger the solidification range of the superalloy, the worse the fluidity. Therefore, for the modified IN939 superalloy, when it exceeds the content range of carbon and boron components provided in the present disclosure, its fluidity becomes poor, wherein the solidification temperature range in Examples 1-5 of the present 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 within the scope of the embodiments of the present disclosure, resulting in the hot workability and service temperature of the alloys. The initial melting temperature of Examples 1-5 of the present disclosure ranges from 1223°C to 1216°C, and the initial melting temperature in Comparative Example 2 is 1206°C.

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

(1) IN939 superalloy is a nickel-based cast superalloy, which belongs to an alloy with a wide crystallization temperature range. For superalloys with a large solidification interval, the solidification process is slow, and a large number of dendrites are easily formed. 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 liquid film torn between the dendrite grain boundaries and form solidification cracks. In the embodiment of the present disclosure, the flow stop is because the IN939 superalloy is accompanied by the growth of dendrites during the solidification process. 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 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 overlap of IN939 superalloy can improve the fluidity of IN939 superalloy, and the speed of dendrite overlap 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 distance between atoms, R _s is the rate of transition of atoms from liquid phase to solid phase, and R _l is the rate of transition rate of atoms 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 gap of the face-centered cubic structure γ dendrite during the solidification process, as the solidification process progresses, the boron and carbon atoms are continuously expelled to the residual In the liquid, a boron-rich film is formed at the front of the solid/liquid interface, and the film thickness of the boron-rich film gradually becomes thicker with the increase of the content of boron and carbon components, thereby reducing the rate of atomic transition from the liquid phase to the solid phase R _s and the rate R _l of the transition from the solid phase to the liquid phase, the growth rate V of 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 superalloys sex.

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

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

In formula (2), Γ is the mass of solute more adsorbed on the 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, resulting in the concentration of boron and carbon elements on the surface of the alloy melt is greater than the concentration in the melt, so that Γ is positive, -C _i /RT is negative, then dσ/(d _Ci ) is negative.

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

As shown in Figure 2, JMatPro software was used to explore the effect of different contents of boron and carbon components in the examples on the surface tension of the modified IN939 superalloy at different temperatures. When the boron and carbon contents in the alloy increased, That is, when the solute concentration C _i increases, the surface tension of the alloy melt decreases, 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 modified IN939 superalloy 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 the content of boron and carbon components in the IN939 superalloy can effectively improve the tensile properties, creep and durability properties of the alloy. The main reason is that in nickel-based superalloys, boron and carbon components tend to fill in 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 bonding force of grain boundaries and reduce the formation rate of grain boundary voids during the endurance process, thereby improving the tensile, creep and endurance properties of the alloy. In addition, after the segregation of boron and carbon at the grain boundary exceeds their solubility, borides and carbides will be precipitated along the grain boundary. 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 boundaries, improve the tensile and lasting and creep properties of the alloy. However, when the content of boron and carbon components in the IN939 superalloy is too high, the borides or carbides in the alloy will be precipitated in the form of blocks or lamellae, and there is a problem of difficulty in deformation during the permanent fracture of the alloy, which is easy to cause microscopic fractures. Pores form and join, deteriorating the tensile and lasting properties of the alloy.

Therefore, considering the influence of boron and carbon components on the comprehensive properties of 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 Improve the flow properties of modified IN939 superalloy on the premise of mechanical properties to meet the needs of advanced aero-engine castings.

The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present disclosure in detail. It should be understood that the above are only specific embodiments of the present disclosure, and are not intended to limit the present disclosure. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure should be included within the protection scope of the present disclosure.

Claims (10)

1. A modified nickel-base cast superalloy, wherein the modified nickel-base cast superalloy comprises: modified IN939 superalloy;

the modified IN939 superalloy comprises the following components IN percentage by mass: 0.11-0.16% of C and 0.006-0.018% of B.

2. The superalloy of claim 1, wherein the composition of the modified IN939 superalloy comprises:

22.24 percent of Cr, 18.73 percent of Co, 1.97 percent of W, 0.89 percent of Nb, 1.24 percent of Ta, 3.66 percent of Ti, 1.90 percent of Al, 0.0063 percent of Mo, 0.0015 percent of P, 0.0035 percent of Mn, 0.11-0.16 percent of C, 0.006 percent of Zr, 0.006 percent-0.018 percent of B, 0.019 percent of Hf, 0.006 percent of V, 0.030 percent of Fe, less than or equal to 0.01 percent of impurity and the balance of Ni, wherein the percentage of each component is mass percent.

3. The superalloy of claim 1, wherein the modified IN939 superalloy has a flowline length IN a flow test at a pour temperature of 1450 ℃ and a form temperature of 900 ℃ comprising: 369-546 mm.

4. The superalloy of claim 1, wherein the liquidus temperature of the modified IN939 superalloy is greater than 1330 ℃;

the working temperatures used for the modified IN939 superalloy included: 0 to 870 ℃.

5. A preparation method of a modified nickel-based casting superalloy comprises the following steps:

putting 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 cast superalloy comprises: unmodified IN939 superalloy.

6. The method of claim 5, wherein the additive comprises: boron particles and carbon powder.

7. The method of claim 6, wherein the amount of boron particles used relative to 2000g of unmodified IN939 alloy comprises: 3-30 g;

the carbon powder is used in an amount comprising: 0-100 g.

8. The method of claim 5, wherein the components IN the unmodified IN939 superalloy comprise:

22.24% of Cr, 18.73% of Co, 0.89% of W, 1.24% of Ta, 3.66% 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 percentage of each component is mass percent.

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

The smelting temperature comprises the following steps: 1550 ℃ and 1600 ℃.

10. The method of claim 5, wherein the time of smelting comprises: 10-30 min.

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