DD451 single-crystal high-temperature alloy for low-cost, high-performance and long-life heavy-duty gas turbine blade and preparation process of DD451 single-crystal high-temperature alloy

Abstract

The invention provides a DD451 single-crystal high-temperature alloy for a low-cost, high-performance and long-service-life heavy-duty gas turbine blade and a preparation process of the DD451 single-crystal high-temperature alloy, and belongs to the technical field of single-crystal high-temperature alloys. The DD451 single crystal high-temperature alloy provided by the invention is prepared from the following components in percentage by mass: 5.2 to 6.4 percent of Al, 6.5 to 9.0 percent of Ta, 0.5 to 2.0 percent of Ti, 0.5 to 2.0 percent of Mo, 0.8 to 2.0 percent of Re, 6.0 to 9.0 percent of W, 5.0 to 8.0 percent of Cr, 7.0 to 10 percent of Co, 0.02 to 0.10 percent of C, 0.001 to 0.005 percent of B, 0.1 to 0.3 percent of Hf and the balance of Ni. The DD451 single-crystal high-temperature alloy provided by the invention has excellent mechanical properties and oxidation resistance under a high-temperature condition, and meanwhile, the DD451 single-crystal high-temperature alloy has relatively high economic benefits.

Description

Technical Field

[0001] This invention relates to the field of single-crystal superalloy technology, and in particular to a low-cost, high-performance, long-life DD451 single-crystal superalloy for heavy-duty gas turbine blades and its preparation process. Background Technology

[0002] The improvement of gas turbine efficiency mainly relies on the continuous increase in turbine inlet temperature. The service environment of heavy-duty gas turbine blades is primarily a multi-field coupled environment of complex thermal, mechanical, and chemical conditions. For E-class and F-class gas turbines, the service temperature is not yet high, and the long-term structural stability of the alloy can be satisfied by sacrificing some high-temperature mechanical properties. However, for large-size single-crystal blades used in 400MW heavy-duty gas turbines, the turbine inlet temperature can reach 1500~1700℃, posing a more severe challenge to the alloy materials used in the blades. Existing gas turbine alloy materials are insufficient for their service temperature requirements. While second-generation single-crystal high-temperature alloys used in aircraft, with higher temperature resistance, meet the service requirements, they cannot meet the requirements for long-term structural stability.

[0003] Based on the service requirements of alloy materials for 400MW heavy-duty gas turbine blades, with service temperatures reaching 950~980℃, the development of single-crystal high-temperature alloys for heavy-duty gas turbine blades that combine low cost, high performance, and long service life is a significant challenge. Summary of the Invention

[0004] The purpose of this invention is to provide a low-cost, high-performance, long-life DD451 single-crystal superalloy for heavy-duty gas turbine blades and its preparation process. The DD451 single-crystal superalloy provided by this invention has both excellent mechanical properties and oxidation resistance under high-temperature conditions, and also has high economic benefits.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a low-cost, high-performance, long-life DD451 single-crystal high-temperature alloy for heavy-duty gas turbine blades, comprising the following components by mass percentage: Al 5.2~6.4%, Ta 6.5~9.0%, Ti 0.5~2.0%, Mo 0.5~2.0%, Re 0.8~2.0%, W 6.0~9.0%, Cr 5.0~8.0%, Co 7.0~10%, C 0.02~0.10%, B 0.001~0.005%, Hf 0.1~0.3%, and the balance Ni.

[0006] Preferably, the low-cost, high-performance, long-life DD451 single-crystal superalloy for heavy-duty gas turbine blades comprises the following components by weight percentage: Al 5.3~6.0%, Ta 7.0~8.5%, Ti 0.8~1.8%, Mo 0.5~1.5%, Re 0.8~1.5%, W 7.5~8.5%, Cr 5.5~6.5%, Co 9.0~10%, C 0.02~0.06%, B 0.002~0.004%, Hf 0.15~0.25%, and the balance Ni.

[0007] Preferably, the low-cost, high-performance, long-life DD451 single-crystal superalloy for heavy-duty gas turbine blades comprises the following components by weight percentage: Al 5.4~5.8%, Ta 7.5~8.0%, Ti 1.0~1.5%, Mo 0.5~1.0%, Re 0.8~1.2%, W 7.5~8.0%, Cr 5.8~6.2%, Co 9.5~10%, C 0.02~0.04%, B 0.002~0.004%, Hf 0.18~0.22%, and the balance Ni.

[0008] Preferably, the low-cost, high-performance, long-life DD451 single-crystal superalloy for heavy-duty gas turbine blades comprises the following components by weight percentage: Al 5.6%, Ta 7.5%, Ti 1.5%, Mo 0.5%, Re 1.0%, W 7.5%, Cr 6.0%, Co 10%, C 0.03%, B 0.003%, Hf 0.2% and balance Ni.

[0009] This invention provides a process for preparing the low-cost, high-performance, long-life DD451 single-crystal superalloy for heavy-duty gas turbine blades described in the above technical solution, comprising the following steps: According to the composition of the DD451 single crystal high-temperature alloy for low-cost, high-performance, long-life heavy-duty gas turbine blades, the raw materials are batched and then smelted to obtain the master alloy. The seed crystal is placed in a seed crystal wax mold and pressed. The master alloy is remelted and cast into a 001 oriented single crystal test rod. After solidification, the low-cost, high-performance, long-life heavy-duty gas turbine blade DD451 single crystal high-temperature alloy is obtained.

[0010] Preferably, the pressing pressure is 6~15MPa, the temperature is 45~70℃, and the time is 10~30s.

[0011] Preferably, the process between pouring and solidification includes heat preservation, wherein the heat preservation temperature is 1520~1570℃ and the time is 10~30min.

[0012] Preferably, the crystal pulling rate of the single crystal specimen during the solidification process is 1.0~5.0 mm / min.

[0013] Preferably, the crystal pulling rate of the single crystal specimen during the solidification process is 2.0~4.0 mm / min.

[0014] Preferably, the melting is vacuum induction melting.

[0015] Beneficial Effects: The DD451 single-crystal superalloy designed in this invention for heavy-duty gas turbine (such as 400MW) blades exhibits excellent mechanical properties and oxidation resistance under high-temperature conditions, while also offering high economic benefits. Specifically, considering the service characteristics of heavy-duty gas turbine blades, this invention employs the synergistic strengthening effect of Al, Ta, and Ti elements to strengthen the γ' phase and Mo, W, and Re elements to strengthen the γ phase. Furthermore, combined with the "W-Ta-Re" co-alloying design method, it achieves high-temperature stability of the γ phase, γ' phase, and the two-phase interface while ensuring low cost. For single-crystal superalloys used in heavy-duty gas turbine blades, solid solution strengthening is the primary strengthening method; if the W and Mo content is too low, it will reduce the durability of the single-crystal superalloy. Simultaneously, the "Co-Cr-Al" co-doping method employed in this invention effectively improves the oxidation resistance of Ni-based single-crystal superalloys. Attached Figure Description

[0016] Figure 1 This is a density comparison chart of DD451 single-crystal high-temperature alloy in Example 3 and other gas turbine alloys; Figure 2 This is a comparison chart of the tensile strength of DD451 single-crystal superalloy and a typical second-generation single-crystal superalloy in Example 3; Figure 3 This is a comparison of the specific strength of DD451 single-crystal superalloy and a typical second-generation single-crystal superalloy at 980°C in Example 3. Figure 4 This is a comparison chart of the creep strength of DD451 single-crystal superalloy in Example 3 and other gas turbine alloys at 760°C. Figure 5 This is a comparison chart of the creep strength of DD451 single-crystal superalloy in Example 3 and other gas turbine alloys at 850°C. Figure 6 This is a comparison chart of the creep strength of DD451 single-crystal high-temperature alloy and other gas turbine alloys in Example 3 at 980°C. Figure 7 This is a comparison chart of the fatigue strength of DD451 single-crystal high-temperature alloy and other gas turbine alloys in Example 3 at 980°C. Figure 8This is a comparison chart of the raw material costs of DD451 single-crystal high-temperature alloy in Example 3 and other alloys used in gas turbines. Detailed Implementation

[0017] This invention provides a low-cost, high-performance, long-life DD451 single-crystal high-temperature alloy for heavy-duty gas turbine blades, comprising the following components by mass percentage: Al 5.2~6.4%, Ta 6.5~9.0%, Ti 0.5~2.0%, Mo 0.5~2.0%, Re 0.8~2.0%, W 6.0~9.0%, Cr 5.0~8.0%, Co 7.0~10%, C 0.02~0.10%, B 0.001~0.005%, Hf 0.1~0.3%, and the balance Ni.

[0018] In one embodiment of the present invention, the heavy-duty gas turbine specifically refers to a 400MW gas turbine; the blade size of the heavy-duty gas turbine can reach 300mm.

[0019] In this invention, the DD451 single-crystal high-temperature alloy for low-cost, high-performance, long-life heavy-duty gas turbine blades comprises, by mass percentage, 5.2-6.4% Al, more specifically 5.3-6.0%, and even more specifically 5.4-5.8%, particularly 5.6%. In this invention, Al is the forming element of the γ'-Ni3Al phase and a key element for the enrichment of the γ'-Ni3Al phase. Increasing the Al content helps to increase the volume fraction of the γ'-Ni3Al phase, hindering dislocation movement and improving the high-temperature performance of the alloy. It also improves the high-temperature oxidation resistance of the Ni3Al single-crystal intermetallic compound. However, excessive Al increases the volume fraction of γ', increases interfacial energy, and leads to structural instability.

[0020] In this invention, the low-cost, high-performance, long-life DD451 single-crystal high-temperature alloy for heavy-duty gas turbine blades, by mass percentage, comprises 6.5-9.0% Ta, more specifically 7.0-8.5%, and even more specifically 7.5-8.0%. In this invention, Ta is also a forming element of the γ'-Ni3Al phase and a key element for the "strength" of the γ'-Ni3Al phase. Increasing the Ta content helps improve the high-temperature thermal stability of the γ'-Ni3Al phase.

[0021] In this invention, the low-cost, high-performance, long-life heavy-duty gas turbine blade DD451 single-crystal high-temperature alloy comprises, by mass percentage, 0.5-2.0% Ti, more specifically 0.8-1.8%, and even more specifically 1.0-1.5%. In this invention, Ti is a γ' phase-forming element, which can significantly improve the high-temperature performance of the alloy.

[0022] In this invention, the low-cost, high-performance, long-life DD451 single-crystal superalloy for heavy-duty gas turbine blades, by mass percentage, comprises 0.5-2.0% Mo, more specifically 0.5-1.5%, and even more specifically 0.5-1.0%. In this invention, Mo is a reinforcing element of the γ'-Ni phase, mainly distributed within it. The alloying design principle of "replacing Re with Mo" adopted in this invention is key to the low cost of Ni3Al single-crystal intermetallic compounds. Simultaneously, Mo's large atomic radius causes lattice distortion in the γ'-Ni phase, increasing the mismatch degree of the Ni3Al single-crystal intermetallic compound, generating a dense network of interfacial dislocations, significantly hindering dislocation movement, and thus improving the high-temperature creep resistance of the Ni3Al single-crystal intermetallic compound.

[0023] In this invention, the DD451 single-crystal superalloy for low-cost, high-performance, long-life heavy-duty gas turbine blades, by mass percentage, comprises 0.8-2.0% Re, more specifically 0.8-1.5%, and even more specifically 0.8-1.2%, and more specifically 1.0%. In this invention, Re is a reinforcing element of the γ'-Ni phase, mainly distributed within it. When Re is enriched at the γ'-Ni3Al / γ'-Ni phase interface, it produces a "Re clustering effect," which significantly hinders dislocation movement and improves high-temperature creep resistance. However, excessive Re content can lead to microstructural instability, generating the TCP phase and reducing the alloy's high-temperature creep resistance. Therefore, the Re content needs to be controlled within a suitable range.

[0024] In this invention, the DD451 single-crystal superalloy for low-cost, high-performance, long-life heavy-duty gas turbine blades comprises, by weight percentage, 6.0% to 9.0% W, more specifically 7.5% to 8.5%, and even more specifically 7.5% to 8.0%. In this invention, W is a solid solution strengthening element, which can improve the creep resistance of the alloy. In this invention, the DD451 single-crystal high-temperature alloy for low-cost, high-performance, long-life heavy-duty gas turbine blades, by mass percentage, comprises 5.0-8.0% Cr, more specifically 5.5-6.5%, and even more specifically 5.8-6.2%, and more specifically 6.0%. In this invention, Cr primarily enhances the oxidation and corrosion resistance of the Ni3Al single-crystal intermetallic compound. However, excessive Cr content can compromise the high-temperature creep resistance of the Ni3Al single-crystal intermetallic compound and generate a large amount of TCP phase during service, reducing the microstructural stability of the Ni3Al single-crystal intermetallic compound. Therefore, the Cr content must be controlled within a suitable range.

[0025] In this invention, the low-cost, high-performance, long-life heavy-duty gas turbine blade DD451 single-crystal superalloy comprises, by weight percentage, 7.0-10% Co, more specifically 9.0-10%, and even more specifically 9.5-10%. Co is a beneficial corrosion-resistant element in this invention, capable of improving the corrosion resistance of the alloy and enhancing its structural stability.

[0026] In this invention, the low-cost, high-performance, long-life heavy-duty gas turbine blade DD451 single-crystal high-temperature alloy comprises, by mass percentage, 0.02~0.10% C, further 0.02~0.06%, even further 0.02~0.04%, specifically 0.03%.

[0027] In this invention, the low-cost, high-performance, long-life heavy-duty gas turbine blade DD451 single-crystal high-temperature alloy comprises, by mass percentage, 0.001~0.005% B, further 0.002~0.004%, specifically 0.003%.

[0028] In this invention, the low-cost, high-performance, long-life heavy-duty gas turbine blade DD451 single-crystal high-temperature alloy comprises, by mass percentage, 0.1-0.3% Hf, further 0.15-0.25%, even further 0.18-0.22%, and specifically 0.2%.

[0029] In this invention, C, B, and Hf are trace elements that can significantly improve the casting process performance of the alloy, increase the fluidity of the alloy liquid, and reduce the micro-shrinkage porosity generated during the solidification process of the alloy. Moreover, trace elements can increase the grain boundary damage tolerance of single crystal alloys. C, B, and Hf are grain boundary strengthening elements. When impurities are generated in the single crystal during processing or service, the presence of grain boundary strengthening elements can significantly improve the damage tolerance of the alloy.

[0030] In this invention, the DD451 single-crystal superalloy for low-cost, high-performance, long-life heavy-duty gas turbine blades comprises, by weight percentage, the balance being Ni. In this invention, Ni is a forming element of the γ'-Ni phase and the γ'-Ni3Al phase.

[0031] This invention provides a process for preparing the low-cost, high-performance, long-life DD451 single-crystal superalloy for heavy-duty gas turbine blades described in the above technical solution, comprising the following steps: According to the composition of the DD451 single crystal high-temperature alloy for low-cost, high-performance, long-life heavy-duty gas turbine blades, the raw materials are batched and then smelted to obtain the master alloy. The seed crystal is placed in a seed crystal wax mold and pressed. The master alloy is remelted and cast into a 001 oriented single crystal test rod. After solidification, the low-cost, high-performance, long-life heavy-duty gas turbine blade DD451 single crystal high-temperature alloy is obtained.

[0032] In this invention, unless otherwise specified, all raw materials used are commercially available products well known to those skilled in the art or prepared using methods well known to those skilled in the art.

[0033] This invention relates to a low-cost, high-performance, long-life heavy-duty gas turbine blade DD451 single-crystal high-temperature alloy. The raw materials are batched and then smelted to obtain a master alloy. In one embodiment of this invention, the smelting can be vacuum induction melting; specifically, in this embodiment, the smelting is carried out in a vacuum induction melting furnace. This invention does not impose any special limitations on the smelting conditions; conditions well-known to those skilled in the art can be used.

[0034] After obtaining the master alloy, the present invention places the seed crystal in a seed crystal wax mold for pressing, and then casts a 001-oriented single crystal test rod after remelting the master alloy. After solidification, the low-cost, high-performance, long-life DD451 single crystal high-temperature alloy for heavy-duty gas turbine blades is obtained. In one embodiment of the present invention, the seed crystal is 001 oriented; the present invention does not have a special limitation on the seed crystal wax mold, and any seed crystal wax mold well known to those skilled in the art can be used. In one embodiment of the present invention, the pressing pressure can be 6~15MPa, specifically 6MPa, 8MPa, 10MPa, 12MPa, or 15MPa; the temperature can be 45~70℃, specifically 45℃, 50℃, 55℃, 60℃, 65℃, or 70℃; the time can be 10~30s, specifically 10s, 15s, 20s, 25s, or 30s. In this embodiment of the present invention, a high-pressure injection molding machine is specifically used for the pressing. The present invention does not have a special limitation on the conditions for remelting and casting the master alloy, and any conditions well known to those skilled in the art can be used. In one embodiment of the present invention, the process between casting and solidification includes heat preservation. The heat preservation temperature can be 1520~1570℃, specifically 1520℃, 1530℃, 1540℃, 1550℃, 1560℃, or 1570℃; the heat preservation time can be 10~30min, specifically 20min. In another embodiment of the present invention, the crystal pulling rate of the single crystal specimen during solidification can be 1.0~5.0mm / min, more specifically 2.0~4.0mm / min, specifically 2.0mm / min, 2.5mm / min, 3.0mm / min, 3.5mm / min, or 4.0mm / min. Specifically, in this embodiment of the present invention, the low-cost, high-performance, long-life DD451 single crystal high-temperature alloy for heavy-duty gas turbine blades is prepared in a single crystal furnace.

[0035] The DD451 single-crystal superalloy described in this invention has at least the following advantages: 1. Has higher heat resistance The turbine inlet temperature of currently mature E-class and F-class gas turbines is approximately 1150~1350℃, while the actual service temperature of the blades does not exceed 900℃. Therefore, existing high-temperature alloy systems for gas turbines focus more on the corrosion resistance of the alloys. This has resulted in the Cr content of existing gas turbine alloys generally being greater than 12wt.%, such as K438 and DZ411, which have Cr contents of 15.8wt.% and 14.2wt.%, respectively. Although the higher Cr content has a significant effect on corrosion resistance, it is somewhat insufficient in improving the alloy's temperature resistance. For 400MW heavy-duty gas turbines, the blade alloy service temperature can reach 980℃, and existing gas turbine alloy systems cannot meet the high-temperature service requirements.

[0036] In this invention, the DD451 single-crystal high-temperature alloy systematically optimizes the ratio of strengthening elements in the Al+Ta+Ti second-phase strengthening phase and the ratio of W+Re solid solution strengthening elements in the γ phase, achieving synergistic strengthening of the γ~γ' phases. That is, while ensuring a certain volume fraction of the γ' phase, the total solid solution strengthening effect is also increased, which greatly improves the high-temperature strength of the alloy and increases the high-temperature resistance of the alloy.

[0037] 2. Exhibits excellent high-temperature and long-term structural stability. Unlike aerospace engines, heavy-duty gas turbines have a longer service life, requiring stable operation for 50,000 hours or more. This necessitates that the alloy materials used in the blades exhibit excellent long-term structural stability during long-term service to ensure the safe and stable operation of the blade components. At the material level, this requires that the alloy's mismatch degree not be too high and that the tendency for TCP phase precipitation be small.

[0038] The service temperature of 400MW heavy-duty gas turbine blades can reach 980℃, approaching the temperature resistance level of second-generation single-crystal superalloys such as Rene N5, DD5, PWA1484, CMSX-4, and DD6. However, these alloys are slightly lacking in long-term high-temperature microstructure stability. For example, the misfit degree of CMSX-4 and DD6 alloys is as high as -0.32% and -0.5%, respectively. Although the misfit strengthening effect has a significant advantage in improving the high-temperature strength of the alloy, the excessive misfit degree will increase the γ / γ' phase interface energy and accelerate the coarsening of the γ / γ' phase interface energy, which is not conducive to improving microstructure stability. Another aspect of long-term microstructure stability needs to consider the tendency of the alloy to precipitate the TCP phase. The calculation of the number of electron vacancies is an effective way to evaluate the tendency of TCP phase precipitation. The Mdt value (number of electron vacancies) of alloys represented by Rene N5 can reach 0.998, indicating a certain tendency of TCP phase precipitation. In this invention, the Mdt value of the DD451 single-crystal superalloy was maintained at 0.971 by adjusting the proportion of heavy elements such as Mo, Re, and W (Example 3), indicating that the alloy has good structural stability and no obvious tendency for TCP phase precipitation under high temperature and long-term service conditions.

[0039] 3. It has significant cost advantages. Currently, high-temperature alloys used in gas turbines are mostly derived from aerospace alloys, with a Re content typically exceeding 2 wt.%. For example, DD5 and PWA1484 have Re contents reaching 3 wt.%, resulting in high alloy costs. To control alloy costs without sacrificing solid solution strengthening effects, this invention employs a "W-for-Re" technical solution, achieving low-Re alloying and significantly reducing costs. The cost of the DD451 single-crystal high-temperature alloy in this invention is only 67% and 60% of that of the mainstream gas turbine alloys DD5 and PWA1484, respectively, demonstrating a significant cost advantage and high potential economic benefits.

[0040] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0041] Examples 1-10 (1) Master alloy melting: Weigh the raw materials according to the weight ratio of the chemical composition of DD451 single crystal high temperature alloy (as shown in Table 1), and melt them in a vacuum induction melting furnace to obtain the master alloy. (2) Single crystal test rod wax mold pressing: The seed crystal is placed in the seed crystal wax mold and the seed crystal wax mold is pressed using a high pressure injection machine. The pressing conditions include: pressure of 9MPa, temperature of 55℃, and heat and pressure holding time of 20s. (3) Single crystal casting: The master alloy was remelted in a single crystal furnace and cast into a 001 oriented single crystal test rod. The rod was held at 1550℃ for 20 min. Then, the crystal pulling rate of the single crystal test rod was controlled at 3.0 mm / min to achieve solidification, thus obtaining DD451 single crystal high temperature alloy.

[0042] Table 1 Chemical composition of DD451 single crystal superalloys in Examples 1-10

[0043] Table 2 shows the durability test results of DD451 single crystal superalloys in Examples 1 to 10. As can be seen from Table 2, the DD451 single crystal superalloy provided by the present invention has excellent durability.

[0044] Table 2. Durability test results of DD451 single-crystal superalloys in Examples 1-10

[0045] Test Example 1 The DD451 single-crystal high-temperature alloy in Example 3 is compared with other alloys used in gas turbines, as follows: Figure 1 Table 3 shows a density comparison between the DD451 single-crystal superalloy in Example 3 and other gas turbine alloys. The specific results are listed in Table 3, along with the Mdt values ​​of each alloy. The results show that, compared to other gas turbine alloys, the DD451 single-crystal superalloy of this invention has a density comparable to that of first-generation single-crystal superalloys and slightly lower than that of second-generation single-crystal superalloys, exhibiting a certain density advantage. Furthermore, the Mdt value of the DD451 single-crystal superalloy in Example 3 is 0.971, indicating good microstructural stability and no significant tendency for TCP phase precipitation under high-temperature, long-term service conditions.

[0046] Table 3 Density of different alloys

[0047] Figure 2 Table 4 shows a comparison of the tensile strength of the DD451 single-crystal superalloy in Example 3 with that of a typical second-generation single-crystal superalloy. Some data are listed in Table 4. The results show that the DD451 single-crystal superalloy of this invention exhibits superior tensile strength across the entire temperature range compared to the typical second-generation single-crystal superalloy.

[0048] Table 4 Tensile strength of different alloys

[0049] Figure 3 The image shows a comparison of the specific strength of the DD451 single-crystal superalloy and a typical second-generation single-crystal superalloy at 980°C in Example 3. The results show that the specific strength of the DD451 single-crystal superalloy of the present invention is significantly better than that of the typical second-generation single-crystal superalloy at 980°C.

[0050] Figure 4 Table 5 shows a comparison of the creep strength of the DD451 single-crystal superalloy in Example 3 with other gas turbine alloys at 760°C. Some data are listed in Table 5. The results show that the creep strength of the DD451 single-crystal superalloy of this invention at 760°C is significantly better than that of traditional directional single-crystal superalloys for gas turbines, mainstream first-generation single-crystal superalloys, and second-generation single-crystal superalloys.

[0051] Table 5. Creep strength of different alloys at 760℃

[0052] Figure 5 Table 6 shows a comparison of the creep strength of the DD451 single-crystal superalloy in Example 3 with other gas turbine alloys at 850°C. Some data are listed in Table 6. The results show that the creep strength of the DD451 single-crystal superalloy of this invention at 850°C is significantly better than that of traditional directional single-crystal superalloys for gas turbines, mainstream first-generation single-crystal superalloys, and second-generation single-crystal superalloys.

[0053] Table 6. Creep strength of different alloys at 850℃

[0054] Figure 6 Table 7 shows a comparison of the creep strength of the DD451 single-crystal superalloy in Example 3 with other gas turbine alloys at 980°C. Some data are listed in Table 7. The results show that the creep strength of the DD451 single-crystal superalloy of this invention at 980°C is significantly better than that of traditional directional single-crystal superalloys for gas turbines, mainstream first-generation single-crystal superalloys, and second-generation single-crystal superalloys.

[0055] Table 7. Creep strength of different alloys at 980℃

[0056] Figure 7 The image shows a comparison of the fatigue strength of the DD451 single-crystal superalloy in Example 3 with other gas turbine alloys at 980°C. The results show that the fatigue strength of the DD451 single-crystal superalloy of the present invention at 980°C is significantly better than that of traditional directional single-crystal superalloys for gas turbines, mainstream first-generation single-crystal superalloys, and second-generation single-crystal superalloys.

[0057] Figure 8 Table 8 shows a comparison of the raw material costs of the DD451 single-crystal superalloy in Example 3 with other gas turbine alloys. Specific data are listed in Table 8. The results show that the DD451 single-crystal superalloy of this invention has a significant cost advantage; compared to the N5 alloy, the cost of the master alloy per batch of working blades is reduced by approximately 40%.

[0058] Table 8 Raw material costs for different alloys (calculated based on a 75% yield)

[0059] Test Example 2 The oxidation resistance of the DD451 single-crystal superalloy prepared in Example 3 was tested and compared with that of the N5 alloy. The test method used was the same as that used for determining the oxidation resistance of HB 5258-2000 steel and superalloys. The specific results are listed in Table 9. The results show that the DD451 single-crystal superalloy of the present invention has excellent oxidation resistance.

[0060] Table 9. Test results of oxidation resistance of the alloy

[0061] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A low-cost, high-performance, long-life DD451 single-crystal superalloy for heavy-duty gas turbine blades, comprising the following components by mass percentage: Al 5.2~6.4%, Ta 6.5~9.0%, Ti 0.5~2.0%, Mo 0.5~2.0%, Re 0.8~2.0%, W 6.0~9.0%, Cr 5.0~8.0%, Co 7.0~10%, C 0.02~0.10%, B 0.001~0.005%, Hf 0.1~0.3% and balance Ni.

2. The low-cost, high-performance, long-life DD451 single-crystal high-temperature alloy for heavy-duty gas turbine blades according to claim 1, characterized in that, Based on mass percentage, it includes the following components: Al 5.3~6.0%, Ta 7.0~8.5%, Ti 0.8~1.8%, Mo 0.5~1.5%, Re 0.8~1.5%, W 7.5~8.5%, Cr 5.5~6.5%, Co 9.0~10%, C 0.02~0.06%, B 0.002~0.004%, Hf 0.15~0.25%, and the balance Ni.

3. The low-cost, high-performance, long-life DD451 single-crystal high-temperature alloy for heavy-duty gas turbine blades according to claim 2, characterized in that, Based on mass percentage, it includes the following components: Al 5.4~5.8%, Ta 7.5~8.0%, Ti 1.0~1.5%, Mo 0.5~1.0%, Re 0.8~1.2%, W 7.5~8.0%, Cr 5.8~6.2%, Co 9.5~10%, C 0.02~0.04%, B 0.002~0.004%, Hf 0.18~0.22%, and the balance Ni.

4. The low-cost, high-performance, long-life DD451 single-crystal high-temperature alloy for heavy-duty gas turbine blades according to claim 3, characterized in that, Based on mass percentage, it includes the following components: Al 5.6%, Ta 7.5%, Ti 1.5%, Mo 0.5%, Re 1.0%, W 7.5%, Cr 6.0%, Co 10%, C 0.03%, B 0.003%, Hf 0.2% and balance Ni.

5. The preparation process of the low-cost, high-performance, long-life heavy-duty gas turbine blade DD451 single-crystal superalloy as described in any one of claims 1 to 4, comprising the following steps: According to the composition of the DD451 single crystal high temperature alloy for low-cost, high-performance, long-life heavy-duty gas turbine blades, the raw materials are batched and then smelted to obtain the master alloy. The seed crystal is placed in a seed crystal wax mold and pressed. The master alloy is remelted and cast into a 001 oriented single crystal test rod. After solidification, the low-cost, high-performance, long-life heavy-duty gas turbine blade DD451 single crystal high-temperature alloy is obtained.

6. The preparation process according to claim 5, characterized in that, The pressing pressure is 6~15MPa, the temperature is 45~70℃, and the time is 10~30s.

7. The preparation process according to claim 5, characterized in that, The process between pouring and solidification includes heat preservation, with the temperature being 1520~1570℃ and the time being 10~30min.

8. The preparation process according to claim 5, characterized in that, The crystal pulling rate of the single crystal specimen during the solidification process is 1.0~5.0 mm / min.

9. The preparation process according to claim 8, characterized in that, The crystal pulling rate of the single crystal specimen during the solidification process is 2.0~4.0 mm / min.

10. The preparation process according to claim 5, characterized in that, The melting process is vacuum induction melting.

Images