High-strength and high-plasticity nickel-cobalt-based wrought superalloy easy to process and preparation method thereof

Abstract

The invention relates to a high-strength and high-plasticity easily-processed nickel-cobalt-based wrought superalloy and a preparation method thereof. The alloy comprises 18%-25% of Co, 11%-16% of Cr, 2.4%-3.4% of Al, 4.5%-6.5% of Ti, 0.8%-2% of W, 1.6%-3.2% of Mo, 0.5%-1.5% of Ta, 0%-1.5% of Nb, 0.001%-0.1% of C, 0.001%-0.05% of B, 0.001%-0.1% of Zr, 0-0.1% of Hf and the balance Ni, and the mass percent ratio of Al to Ti is smaller than or equal to 0.6. The sum of the mass percentages of W and Mo is 3-5%; the sum of the mass percentages of Nb and Ta is 0-2%; the ratio of the mass percent of the Co element to the mass percent of W + Mo is greater than or equal to 4; the ratio of the mass percent of the Al element to the mass percent of Nb + Ta is larger than or equal to 2, and the volume fraction of a gamma'strengthening phase of the high-temperature alloy is 40%-60%. The alloy element distribution in the gamma phase and the gamma'phase is adjusted through the reasonable element proportion, on one hand, the alloy has a large machining interval while the high gamma 'phase volume fraction is kept, and on the other hand, the alloy stacking fault energy is adjusted to make full use of the strengthening effect of the interaction effect of surface defects on the alloy.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high-temperature alloys, and particularly relates to a nickel-cobalt-based deformed high-temperature alloy with high strength and plasticity and easy processing and a preparation method thereof. BACKGROUND

[0002] High-temperature alloys are widely used in hot-end components of aero-engines and industrial gas turbines due to their excellent high-temperature strength, good oxidation resistance and thermal corrosion resistance, and are irreplaceable key metal materials for national defense and economic development.

[0003] With the development of aero-engines and industrial gas turbines, the turbine inlet temperature is continuously increased. The temperature resistance requirement of the turbine disc material of the aero-engine has reached 760 DEG C, and in some higher military equipment fields, the temperature has reached 815 DEG C. The stable service temperature of the currently widely used GH4169 alloy is only 650 DEG C, and the service temperature of the U720Li alloy with higher comprehensive performance is also not more than 700 DEG C, and its temperature resistance capacity cannot meet the use requirement, and a new type of high-temperature alloy needs to be designed to meet the above requirements.

[0004] A foreign patent technology discloses a design method of a nickel-cobalt-based high-temperature alloy [US9945019B2], which obtains a TMW series alloy with higher strength in the medium temperature zone by adding a certain proportion of Co-Ti alloy on the basis of U720Li. The alloy contains, by mass percentage, Co: 23.1% to 55%, Cr: 2% to 25%, Ta: 0 to 10%, W: 0 to 10%, Mo: 0 to 10%, Zr: 0 to 0.5%, Nb: 0 to 5%, Ti: 3% to 15.0%, Al: 0.2% to 7%, Re: 0 to 5%, V: 0 to 2%, Fe: 0 to 2%, Hf: 0 to 2%, Mg: 0 to 0.1%, C: 0 to 0.5%, B: 0 to 0.1%, and the balance of Ni.

[0005] A domestic patent technology discloses a high-temperature alloy GH4251 with low stacking fault energy [CN112981186B], which contains, by mass percentage, C: 0.01% to 0.09%, Co: 23.5% to 27.5%, Cr: 11% to 15%, W: 0.1% to 1.8%, Al: 2.2% to 2.6%, Ti: 3.5% to 5.5%, Nb: 0 to 2%, Ta: 0 to 2%, Mo: 2.1% to 3.5%, B: 0.0001% to 0.05%, Zr: 0.0001% to 0.05%, Fe: 0 to 2.5%, Mg: 0 to 0.04%, and the balance of Ni.

[0006] It is reported that the temperature resistance of the above two types of alloys can reach 750 DEG C, and the microstructure stability is excellent, wherein the yield strength of TMW nickel-cobalt-based high-temperature alloy at 750 DEG C can reach 1008 MPa, and the elongation after fracture can reach 9.5%; the yield strength of low-layer dislocation energy high-temperature alloy GH4251 at 750 DEG C can reach 965 MPa, and the elongation after fracture can reach 8.5%, which is expected to meet the service requirements of hot end components above 750 DEG C.

[0007] It can be seen that the yield strength of the currently reported alloy at 750 DEG C is not more than 1100 MPa, and the elongation after fracture is not more than 10%, and there is a restriction between the yield strength and the elongation after fracture of the alloy. The high-strength deformed high-temperature alloy mostly has the problem of medium-temperature brittleness, and the elongation after fracture is less than 5%, and the yield strength of the alloy with high elongation after fracture is usually less than 1000 MPa. With the development of advanced equipment, the existing alloy gradually exposes the short board in the application, and it is difficult to meet the increasing comprehensive performance index requirements of high-temperature alloy for 750 DEG C and above. When designing the alloy, the contradiction between the volume fraction of the gamma prime phase, the melting point, the castability and the hot workability of the alloy, and the influence of the synergistic effect of the layer dislocation, the dislocation and the gamma prime phase on the strength of the alloy are fully considered, which is expected to realize the synergistic improvement of the performance of the alloy. SUMMARY

[0008] In order to overcome the above problems existing in the prior art, the present application provides a high-strength plastic and easy-to-process nickel-cobalt-based deformed high-temperature alloy and a preparation method, which are used to solve the above problems existing in the prior art.

[0009] A high-strength plastic and easy-to-process nickel-cobalt-based deformed high-temperature alloy, comprising, in mass percentage: Co 18% to 25%, Cr 11% to 16%, Al 2.4% to 3.4%, Ti 4.5% to 6.5%, W 0.8% to 2%, Mo 1.6% to 3.2%, Ta 0.5% to 1.5%, Nb 0% to 1.5%, C 0.001% to 0.1%, B 0.001% to 0.05%, Zr 0.001% to 0.1%, Hf 0 to 0.1%, and the balance of Ni, wherein the mass percentage ratio of Al and Ti is less than or equal to 0.6; the sum of the mass percentages of W and Mo is 3% to 5%; the sum of the mass percentages of Nb and Ta is 0% to 2%; the ratio of the mass percentage of Co to the mass percentage of W+Mo is greater than or equal to 4; the ratio of the mass percentage of Al to the mass percentage of Nb+Ta is greater than or equal to 2, and the volume fraction of the gamma prime strengthening phase of the high-temperature alloy is 40% to 60%.

[0010] According to the aspect and any possible implementation manner thereof as above, further provided is an implementation manner, the high-temperature alloy comprises, in mass percentage, Co 20-25%, Cr 12-13.5%, Al 2.7-3.2%, Ti 4.5-6.5%, W 1.2-1.8%, Mo 2-2.6%, Ta 0-1.5%, Nb 0-1.5%, C 0.01-0.05%, B 0.001-0.04%, Zr 0.001-0.04%, Hf 0-0.04%, and the balance is Ni.

[0011] According to the aspect and any possible implementation manner thereof as above, further provided is an implementation manner, the mass percentage of Co is 20-24%, and the mass percentage ratio of Cr to Co is greater than or equal to 0.5.

[0012] According to the aspect and any possible implementation manner thereof as above, further provided is an implementation manner, the high-temperature alloy has a yield strength of 1100 MPa or more at 750 ℃, and an elongation after fracture of 8% or more; a creep life of 180 h or more at 760 ℃ and 480 MPa; and an elongation after fracture of 1200% or more when stretched at a strain rate of 10 -2 s -1 According to the aspect and any possible implementation manner thereof as above, further provided is an implementation manner, the high-temperature alloy has a yield strength of 1100 MPa or more at 750 ℃, and an elongation after fracture of 8% or more; a creep life of 180 h or more at 760 ℃ and 480 MPa; and an elongation after fracture of 1200% or more when stretched at a strain rate of 10

[0013] According to the aspect and any possible implementation manner thereof as above, further provided is an implementation manner, the high-temperature alloy comprises, in mass percentage, Co 20-25%, Cr 12-13.5%, Al 2.7-3.2%, Ti 4.5-6.5%, W 1.2-1.8%, Mo 2-2.6%, Ta 0-1.5%, Nb 0-1.5%, C 0.01-0.05%, B 0.001-0.04%, Zr 0.001-0.04%, Hf 0-0.04%, and the balance is Ni.

[0014] According to the aspect and any possible implementation manner thereof as above, further provided is an implementation manner, the high-temperature alloy comprises, in mass percentage, Co 20-25%, Cr 12-13.5%, Al 2.7-3.2%, Ti 4.5-6.5%, W 1.2-1.8%, Mo 2-2.6%, Ta 0-1.5%, Nb 0-1.5%, C 0.01-0.05%, B 0.001-0.04%, Zr 0.001-0.04%, Hf 0-0.04%, and the balance is Ni.

[0015] According to the aspect and any possible implementation manner thereof as above, further provided is an implementation manner, the sum of the mass percentages of W and Mo is 3-5%, wherein the mass percentage of W is 1-2%, and the mass percentage of Mo is 2-3%.

[0016] According to the aspect and any possible implementation manner as above, further provided is an implementation manner, wherein the sum of the mass percentages of the Al and the Ti is 7% to 9%.

[0017] The application further provides a preparation method of the high-strength and high-plasticity and easy-to-process nickel-cobalt-based wrought superalloy.

[0018] S1. adding raw materials into a vacuum induction furnace to melt the alloy ingot;

[0019] S2. homogenizing the alloy ingot, first at 1050-1150 °C for 12 h, then at 1150-1200 °C for 16 h, and air cooling to room temperature;

[0020] S3. performing a canning extrusion treatment on the homogenized alloy at 1060-1090 °C, air cooling after extrusion, and preparing an alloy rod;

[0021] S4. solid solution treatment of the alloy rod at 1100 °C for 2 h, then aging treatment at 900 °C for 4 h, air cooling to room temperature, and finally aging treatment at 760 °C for 12 h, air cooling to room temperature.

[0022] According to the aspect and any possible implementation manner as above, further provided is an implementation manner, wherein the S1 comprises:

[0023] S11. adding Ni, Co, Cr, Ti, W, Mo, Nb and Ta with high melting points into a vacuum induction furnace to smelt intermediate alloys;

[0024] S12. adding Al, C, B, Zr and Hf into the intermediate alloys to smelt a metal liquid, and casting the metal liquid into an alloy ingot.

[0025] Advantages of the application

[0026] The high-strength plastic and easy-to-process nickel-cobalt-based high-temperature alloy of the present application comprises, in mass percentage, Co 18-25%, Cr 11-16%, Al 2.4-3.4%, Ti 4.5-6.5%, W 0.8-2%, Mo 1.6-3.2%, Ta 0.5-1.5%, Nb 0-1.5%, C 0.001-0.1%, B 0.001-0.05%, Zr 0.001-0.1%, Hf 0-0.1%, and the balance of Ni. The present application adjusts the distribution of alloying elements in the gamma phase and the gamma prime phase by reasonable element ratio, on the one hand, so that the alloy has a larger processing interval while maintaining a high volume fraction of gamma prime phase, and on the other hand, adjusts the alloy stacking fault energy to fully utilize the interaction of surface defects to strengthen the alloy. The combined effect of the two provides a solution to the nickel-cobalt-based deformed high-temperature alloy with high strength, high plasticity and easy processing, and further provides a new solution for high-strength high-temperature alloy for advanced equipment serving at 750 DEG C and above. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 Fig. 1 is a SEM microstructure diagram of the alloy of Example 1 of the present application, Fig. 2 is an EBSD microstructure diagram of the alloy of Example 1 of the present application, and Fig. 3 is a tensile creep curve of the alloy of Example 1 of the present application at 760 DEG C / 480 MPa.

[0028] Figure 2 Fig. 4 is a TEM microstructure diagram of the deformed structure of the alloy of Example 2 of the present application, Fig. 5 is a high-resolution atomic image of the deformed structure of the alloy of Example 2 of the present application, and Fig. 6 is a tensile creep curve of the alloy of Example 2 of the present application at 760 DEG C / 480 MPa. DETAILED DESCRIPTION

[0029] In order to better understand the technical solutions of the present application, the present application includes but is not limited to the specific embodiments described below, and similar technologies and methods should be considered as within the scope of the present application. In order to make the technical problems, technical solutions and advantages of the present application more clear, the following will be described in detail with reference to the drawings and specific embodiments.

[0030] It should be clear that the embodiments described in the present application are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0031] The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in the description of the application and the appended claims, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0032] The present application provides a high-strength plastic, easy-to-process nickel-cobalt-based wrought superalloy and a preparation method thereof, which is to develop an alloy with higher yield strength, greater elongation after fracture and good creep performance at medium temperature and good plastic deformation forming capacity at high temperature. Further, the yield strength of the superalloy at 750℃ is above 1100MPa, the elongation after fracture is above 8%, the creep life at 760℃@480MPa is above 180h, and the elongation after fracture is above 1200% when stretched at a strain rate of 10 -2 s -1

[0033] To achieve the above object, the present application adopts the following technical scheme:

[0034] The high-strength plastic, easy-to-process nickel-cobalt-based superalloy comprises, in mass percentage, Co 18% to 25%, Cr 11% to 16%, Al 2.4% to 3.4%, Ti 4.5% to 6.5%, W 0.8% to 2%, Mo 1.6% to 3.2%, Ta 0.5% to 1.5%, Nb 0% to 1.5%, C 0.001% to 0.1%, B 0.001% to 0.05%, Zr 0.001% to 0.1%, Hf 0 to 0.1%, and the balance of Ni.

[0035] Preferably, the high-strength plastic, easy-to-process nickel-cobalt-based superalloy comprises, in mass percentage, Co 21% to 23%, Cr 12% to 13%, Al 2.7% to 3.1%, Ti 4.5% to 6%, W 1.2% to 1.6%, Mo 2.1% to 2.6%, Ta 0% to 1.2%, Nb 0% to 1.2%, C 0.01% to 0.04%, B 0.001% to 0.03%, Zr 0.001% to 0.03%, Hf 0 to 0.03%, and the balance of Ni.

[0036] ​Preferably, the high-temperature alloy comprises, in mass percentage: Co 20%~23%, Cr 12%~13.5%, Al 2.7%~3.2%, Ti 4.5%~6.5%, W 1.2%~1.8%, Mo 2%~2.6%, Ta 0%~1.5%, Nb 0%~1.5%, C 0.01%~0.05%, B 0.001%~0.04%, Zr 0.001%~0.04%, Hf 0~0.04%, and the balance being Ni.

[0037] The mass percentage ratio of Al to Ti is ≤0.6, so as to improve the medium-temperature strength of the alloy; the sum of the mass percentages of W and Mo is between 3% and 5%, so as to ensure the solid solution strengthening effect of the alloy and improve the creep life of the alloy; the sum of the mass percentages of Nb and Ta is between 0% and 2%, so as to reduce the stacking fault energy of the alloy, improve the yield strength of the alloy, and ensure the microstructure stability of the alloy.

[0038] The ratio of the mass percentage of Co to the mass percentage of W+Mo is ≥4, so as to control the solid solubility of refractory elements; the ratio of the mass percentage of Al to the mass percentage of Nb+Ta is ≥2, so as to ensure the contribution of Ni3Al phase to the strength and creep performance of the alloy.

[0039] Further, the mass percentage of Co is between 20% and 24%, and the mass percentage ratio of Cr to Co is ≥0.5, so as to improve the oxidation corrosion resistance of the alloy.

[0040] Further, the sum of the mass percentages of W and Mo is between 3% and 5%, wherein the mass percentage of W is 1%~2% and the mass percentage of Mo is 2%~3%, so as to reduce the tendency of TCP harmful phase precipitation on the premise of ensuring the solid solution strengthening effect.

[0041] Further, the sum of the mass percentages of Al and Ti is 7%~9%, so as to control the volume fraction of the alloy strengthening phase γ' phase to be between 40% and 60%.

[0042] As an embodiment of the present disclosure, the present disclosure provides a preparation method of a high-strength and high-plasticity, easy-to-process nickel-cobalt-based wrought high-temperature alloy, which comprises alloy smelting, extrusion deformation and heat treatment processes, and the steps are as follows:

[0043] (1) The alloy raw materials are added into a vacuum induction furnace for smelting. The process is divided into two steps. First, the elements with relatively high melting points, such as Ni, Co, Cr, Ti, W, Mo, Nb and Ta, are smelted into intermediate alloys, and then the volatile Al and trace elements C, B and Zr are smelted to control the loss of alloy elements. Finally, the metal liquid is cast to obtain an alloy ingot;

[0044] (2) the alloy ingot is subjected to step-by-step homogenization treatment, first at 1050-1150 DEG C for 12h, and then at 1150-1200 DEG C for 16h, and air cooling to room temperature, so that under the premise of not causing initial melting, part of the primary gamma prime phase is retained for pinning grain boundaries, and the dendritic segregation is reduced, laying a foundation for the next deformation processing;

[0045] (3) the homogenized alloy is subjected to canning extrusion treatment at 1060-1090 DEG C, with an extrusion ratio of 2.5-4, and air cooling after extrusion, to prepare an alloy rod, and the alloy is extruded in this temperature range to cause dynamic recrystallization, and a fine-grained structure is obtained after extrusion;

[0046] (4) the alloy rod prepared by extrusion is subjected to solid solution treatment at 1100 DEG C for 2h, and then aged at 900 DEG C for 4h, and air cooled to room temperature, and finally aged at 760 DEG C for 12h, and air cooled to room temperature, so that fine strengthening gamma prime phase is precipitated in the grains;

[0047] The high-temperature alloy prepared according to the method (melting, canning extrusion, solid solution aging) has gamma prime phase for pinning grain boundaries and intragranular strengthening gamma prime phase, and the volume fraction of the intragranular strengthening phase is between 40% and 60%, so that the strength and plasticity of the alloy can be fully coordinated. When the alloy workpiece is subjected to plastic deformation at a temperature of 0.48-0.68T m and a strain rate of 10 -4 -10 -2 s -1 , the characteristics of low stacking fault energy make the alloy deformation structure contain both stacking faults and micro-twins, and the thickness of the micro-twins is less than 100nm; wherein T m is the melting point of the alloy.

[0048] The design principles of the alloying elements and the component range in the present application are as follows:

[0049] Cobalt: Co is the most important element in the alloy of the present application. On the one hand, the addition of Co can significantly reduce the stacking fault energy of the gamma matrix of the alloy, which is conducive to promoting the decomposition of a / 2<110> type dislocations into incomplete dislocations at high temperatures, and then forming stacking faults and micro-twins, and promoting the transformation of stacking faults into micro-twins, and acting with the gamma prime phase to achieve strengthening effect. On the other hand, the interaction of the added Co element with the Ni element increases the volume fraction of the secondary gamma prime phase, and thus improves the mechanical properties of the alloy. Therefore, the mass percentage of Co element is 18%-25%, preferably 20%-23%.

[0050] Chromium: Cr element is an important element to ensure the alloy oxidation resistance and corrosion resistance, and because its atomic radius is larger than that of Ni and Co, it also has the effect of solid solution strengthening and reducing the stacking fault energy. However, excessive addition of Cr element will lead to the precipitation of harmful phases such as sigma phase, which will damage the mechanical properties of the alloy. Therefore, the mass percentage of Cr element is 11% to 16%, preferably 12% to 13.5%.

[0051] Aluminum: Al element is one of the main forming elements of strengthening phase γ', which mainly plays the role of precipitation strengthening and high temperature oxidation resistance. The addition of Al element can significantly improve the high temperature mechanical properties of the alloy, but when the content of Al element is too high, the hot working performance of the alloy will be poor. Therefore, the mass percentage of Al element is 2.4% to 3.4%, preferably 2.7% to 3.2%.

[0052] Titanium: Ti element is one of the main forming elements of strengthening phase γ', which plays an important role in the medium temperature strength of the alloy. The addition of Ti element can also increase the volume fraction and dissolution temperature of γ' strengthening phase, and improve the mechanical properties of the alloy. However, when the content of Ti element is too high, harmful phase η phase is easy to precipitate in the alloy, which will damage the mechanical properties of the alloy. Therefore, the mass percentage of Ti element is 4.5% to 6.5%, preferably 4.5% to 6.5%.

[0053] Tungsten: W element is a significant solid solution strengthening element, which can increase the strength of γ phase and γ' phase at the same time. In nickel-cobalt-based high-temperature alloy, it mainly enters γ' phase, which can control the coarsening rate of γ' phase and improve the creep resistance of the alloy. However, when the content of W is too high, it will increase the tendency of harmful phase μ phase to precipitate, leading to the decline of the alloy performance, and the increase of W content will also increase the density of the alloy, limiting the application range of the alloy. Therefore, the mass percentage of W element is 0.8% to 2%, preferably 1.2% to 1.8%.

[0054] Molybdenum: Mo element is a strong solid solution strengthening element, which preferentially enters the γ matrix in nickel-cobalt-based high-temperature alloy to play the role of solid solution strengthening. Excessive addition of Mo element will lead to the precipitation of harmful phase σ phase, which will damage the mechanical properties of the alloy. Therefore, the mass percentage of Mo element is 1.6% to 3.2%, preferably 2% to 2.6%.

[0055] Tantalum: Ta is an important element that must be added in the alloy of the present application. On the one hand, Ta element is a γ' phase forming element, which can increase the volume fraction of γ' strengthening phase, on the other hand, the addition of Ta element can reduce the stacking fault energy of the alloy γ matrix, making the alloy more easily form stacking faults and micro-twins, which is the key guarantee for the strength of the alloy at 750℃. However, excessive content of Ta element may increase the tendency of D0 19 harmful phase to precipitate, which will damage the mechanical properties of the alloy. Therefore, the mass percentage of Ta element is 0.5% to 1.5%, preferably 0.5% to 1.5%.

[0056] Niobium: Nb element is a γ' phase forming element, and can reduce the stacking fault energy of the γ matrix of the alloy, but too high Nb element content can easily cause the generation of δ-Ni3Nb phase. Therefore, the mass percentage of Nb element is 0% to 1.5%, preferably 0% to 1.5%.

[0057] Carbon: C element is an important grain boundary strengthening element, and can also improve the casting performance of the alloy. C element is segregated at the grain boundary to form MC, M6C, M 23 C6 carbides, which can improve the mechanical properties of the alloy. However, when the C content is too high, the continuous precipitation of carbides at the grain boundary will damage the mechanical properties of the alloy. Therefore, the mass percentage of C element is 0.001% to 0.1%, preferably 0.01% to 0.05%.

[0058] Boron: B element is segregated at the grain boundary, which can improve the grain boundary strength of the alloy, improve the hot deformation performance of the alloy, and improve the tensile plasticity of the alloy. However, when the B element content is too high, low-melting-point borides are easily formed between the dendrites, making it difficult to homogenize the alloy. Therefore, the mass percentage of B element is 0.001% to 0.05%, preferably 0.001% to 0.04%.

[0059] Zirconium: Zr element is segregated at the grain boundary, which can improve the plasticity and fatigue performance of the alloy, but too high Zr element content will also make it difficult to homogenize the alloy. Therefore, the mass percentage of Zr element is 0.001% to 0.1%, preferably 0.001% to 0.04%.

[0060] Hafnium: Hf element is segregated at the grain boundary, which can inhibit grain boundary sliding and crack initiation, and improve the high-temperature creep strength and endurance life of the alloy, but too high Hf element content will form brittle Hf-rich phases, resulting in a decrease in the elongation after fracture of the alloy. Therefore, the mass percentage of Hf element is 0 to 0.1%, preferably 0 to 0.04%.

[0061] The reasonable proportioning of the above alloy elements is the guarantee for the high-strength, high-plasticity, and easy-to-process nickel-cobalt-based high-temperature alloy to obtain excellent room temperature and high temperature performance.

[0062] The present application will be further described through specific examples as follows:

[0063] Example 1

[0064] Example 1 prepares a high-strength, high-plasticity, and easy-to-process nickel-cobalt-based high-temperature alloy, wherein the chemical composition of the high-temperature alloy is, in terms of mass percentage: Co 22%, Cr 12.5%, Al 2.9%, Ti 5.5%, W 1.6%, Mo 2.4%, Ta 0.5%, Nb 0.5%, C 0.02%, B 0.02%, Zr 0.03%, Hf 0.01%, and the balance is Ni.

[0065] The high-temperature alloy is prepared in the following manner:

[0066] 1) Alloy raw materials are added into a vacuum induction furnace for smelting. The process is divided into two steps. First, elements with high melting points such as Ni, Co, Cr, Ti, W, Mo, Nb, Ta, etc. are smelted into intermediate alloy, and then volatile Al and trace elements C, B, Zr, Hf are smelted, and the molten metal is cast into an alloy ingot.

[0067] 2) The alloy ingot is subjected to homogenization treatment. First, it is treated at 1100℃ for 12h, and then treated at 1175℃ for 16h, and air-cooled to room temperature.

[0068] (3) The homogenized alloy is subjected to canning extrusion treatment at 1180℃, with an extrusion ratio of 3.5, and air-cooled after extrusion, to prepare an alloy rod.

[0069] 4) The extruded alloy rod is subjected to solid solution treatment at 1100℃ for 2h, and then aged at 900℃ for 4h, and air-cooled to room temperature, and finally aged at 760℃ for 12h, and air-cooled to room temperature.

[0070] The microstructure photograph of the high-temperature alloy obtained according to the present embodiment is shown in Figure 1 , where (a) is the SEM microstructure of the alloy after heat treatment, and it can be seen that the primary γ' phase pinning the grain boundaries has a control effect on grain growth during heat treatment; there are also secondary γ' phases precipitated in the grains, which have a precipitation strengthening effect, (b) is the EBSD image of the grain structure of the alloy after heat treatment, and the average grain size of the alloy is about 9μm, which can have a significant grain refinement effect, thereby making the alloy have a high yield strength.

[0071] The alloy prepared in the present embodiment has a tensile yield strength of 1110MPa and a tensile strength of 1163MPa at a strain rate of 10 -3 s -1 at 750℃, and an elongation of 9.0% after fracture.

[0072] The creep life of the alloy under the condition of 760℃@480MPa is 180h, as shown in Figure 1 (c).

[0073] Example 2

[0074] Example 2 prepares a high-strength and high-plasticity, easy-to-process nickel-cobalt-based high-temperature alloy, wherein the chemical composition of the high-temperature alloy, in terms of mass percentage, is: Co 22%, Cr 12.5%, Al 2.9%, Ti 5.5%, W 1.6%, Mo 2.4%, Ta 1%, C 0.02%, B 0.02%, Zr 0.03%, Hf 0.02, and the balance is Ni.

[0075] The high-temperature alloy is prepared in the following manner:

[0076] 1) Alloy raw materials are added into a vacuum induction furnace for smelting. The process is divided into two steps. First, elements with high melting points such as Ni, Co, Cr, Ti, W, Mo, Nb, Ta, etc. are smelted into intermediate alloys, and then volatile Al and trace elements C, B, Zr, Hf are smelted, and the molten metal is cast into alloy ingots.

[0077] 2) The alloy ingots are subjected to homogenization treatment. First, they are treated at 1175℃ for 12h, and then treated at 1200℃ for 16h, and air-cooled to room temperature.

[0078] (3) The homogenized alloy is subjected to canning extrusion treatment at 1180℃, with an extrusion ratio of 3.5, and air-cooled after extrusion to prepare alloy rods.

[0079] 4) The extruded alloy rods are subjected to solid solution treatment at 1100℃ for 2h, and then aged at 900℃ for 4h, air-cooled to room temperature, and finally aged at 760℃ for 12h, air-cooled to room temperature.

[0080] A portion of the alloy rods after heat treatment is cut as a processing piece, and subjected to tensile testing at 750℃ at a strain rate of 10 -3 s -1 , and then at 1050℃ at a strain rate of 10 -2 s -1 . The microstructure of the alloy after tensile testing is shown in Figure 2 , wherein Figure 2 (a) is a bright field phase containing stacking faults and micro-twins in the tensile microstructure of the alloy, and a large number of mutually parallel stacking faults and micro-twins prove that the means of reducing stacking fault energy to increase the density of stacking faults and micro-twins contributes to the strength of the alloy at 750℃, Figure 2 (b) is a high-resolution image of micro-twins in the tensile microstructure of the alloy, which shows that micro-twins can coordinate deformation by thickening, thereby improving the plasticity of the alloy.

[0081] The test results show that the yield strength of the alloy at 750℃ is 1141MPa, the tensile strength is 1218MPa, and the elongation after fracture is 10.6%; the elongation after fracture of the alloy at 1050℃ is 1240%, and the alloy has excellent strength and plasticity and hot working performance.

[0082] The test results show that the creep life of the alloy at 760℃ under the condition of 480MPa is 183h, as shown in Figure 2 (c).

[0083] The foregoing description illustrates and describes several preferred embodiments of the present application, but it is to be understood that the application is not limited to the above-described forms, and that it should not be seen as excluding other embodiments, but rather as being applicable in a variety of other combinations, modifications and environments, and capable of being altered in various ways within the scope of the application as described in the claims, by the teaching or knowledge of the relevant art, or by the common general knowledge. Any alterations and further modifications in the application made by a person of ordinary skill in the art are to be construed as being within the scope of the application as defined in the appended claims.

Claims

1. A high-strength, ductile, easily processable nickel-cobalt-based wrought superalloy characterized in that, The high-temperature alloy comprises, in mass percentage: Co 18% to 25%, Cr 11% to 16%, Al 2.4% to 3.4%, Ti 4.5% to 6.5%, W 0.8% to 2%, Mo 1.6% to 3.2%, Ta 0.5% to 1.5%, Nb 0% to 1.5%, C 0.001% to 0.1%, B 0.001% to 0.05%, Zr 0.001% to 0.1%, Hf 0 to 0.1%, and the balance of Ni, wherein a mass percentage ratio of the Al to the Ti is less than or equal to 0.6; a mass percentage sum of the W and the Mo is 3% to 5%; a mass percentage sum of the Nb and the Ta is 0% to 2%; a mass percentage ratio of the Co to the mass percentage sum of the W and the Mo is greater than or equal to 4; and a mass percentage ratio of the Al to the mass percentage sum of the Nb and the Ta is greater than or equal to 2, and a volume fraction of a gamma-prime strengthening phase of the high-temperature alloy is 40% to 60%.

2. The alloy of claim 1 wherein, The high-temperature alloy comprises, in mass percentage: Co 20% to 25%, Cr 12% to 13.5%, Al 2.7% to 3.2%, Ti 4.5% to 6.5%, W 1.2% to 1.8%, Mo 2% to 2.6%, Ta 0% to 1.5%, Nb 0% to 1.5%, C 0.01% to 0.05%, B 0.001% to 0.04%, Zr 0.001% to 0.04%, Hf 0 to 0.5%, and the balance of Ni.

3. The alloy according to claim 1 or 2, characterized in that The mass percentage of the Co is 20% to 24%, and a mass percentage ratio of the Cr to the Co is greater than or equal to 0.

5.

4. The alloy according to claim 1 or 2, characterized in that The high-temperature alloy has a yield strength of 1100 MPa or more at 750°C, an elongation after fracture of 8% or more, a creep life of 180 h or more at 760°C under 480 MPa, and an elongation after fracture of 1200% or more when stretched at 1050°C at a strain rate of 10 -2 s -1 -1 / s.

5. The alloy according to claim 1 or 2, characterized in that The high-temperature alloy comprises, in mass percentage: Co 22%, Cr 12.5%, Al 2.9%, Ti 5.5%, W 1.6%, Mo 2.4%, C 0.02%, B 0.02%, Zr 0.03%, and the balance of Ni.

6. The alloy of claim 1 wherein, The high-temperature alloy comprises, in mass percentage: Co 21% to 23%, Cr 12% to 13%, Al 2.7% to 3.1%, Ti 4.5% to 6%, W 1.2% to 1.6%, Mo 2.1% to 2.6%, Ta 0% to 1.2%, Nb 0% to 1.2%, C 0.01% to 0.04%, B 0.001% to 0.03%, Zr 0.001% to 0.03%, Hf 0 to 0.03%, and the balance of Ni.

7. The alloy of claim 1 or 2 wherein, A mass percentage sum of the W and the Mo is 3% to 5%, wherein a mass percentage of the W is between 1% and 2%, and a mass percentage of the Mo is between 2% and 3%.

8. The alloy of claim 1 or 2 wherein, A mass percentage sum of the Al and the Ti is 7% to 9%.

9. A method of producing a high-strength, high-ductility, easily processable nickel-cobalt-based wrought superalloy, characterized in that, The method for preparing the alloy of any one of claims 1 to 8 comprises the following steps: S1. raw materials are added into a vacuum induction furnace to melt the alloy ingot; S2. the alloy ingot is subjected to homogenization treatment, first at 1050°C to 1150°C for 12 hours, and then at 1150°C to 1200°C for 16 hours, and air cooling to room temperature; S3. the alloy after homogenization is subjected to a canning extrusion treatment at 1060°C to 1090°C, and air cooling after extrusion, to prepare an alloy rod; S4. The alloy bar is solid-solution treated at 1100℃ for 2h, then aged at 900℃ for 4h, air-cooled to room temperature, and finally aged at 760℃ for 12h, air-cooled to room temperature.

10. The method of claim 9, wherein, The S1 comprises: S11. Adding Ni, Co, Cr, Ti, W, Mo, Nb, Ta with high melting point into a vacuum induction furnace for smelting into an intermediate alloy; S12. Adding Al, C, B, Zr, Hf into the intermediate alloy for smelting to obtain a metal liquid, and casting the metal liquid into an alloy ingot.

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