A cyclic temperature hot isostatic pressing treatment process for K4169 nickel-based superalloy
Patent Information
- Application Number
- CN202611254316.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-08-18
- Publication Date
- 2026-10-30
AI Technical Summary
[0006]为了克服背景技术中的问题，本发明通过对K4169镍基高温合金铸件进行高低温往复循环热等静压处理，利用循环热应力、温度梯度作用在孔隙、微裂纹缺陷界面诱发位错增殖、动态回复与动态再结晶，无需塑性变形等附加处理，解决铸件内部微孔、疏松焊合不彻底，缺陷界面结合强度，服役易二次开裂，晶粒粗化等问题，实现铸件强塑性同步提升，从而提高铸件综合使用性能
1. 本发明通过循环变温热等静压处理，产生周期性热应力，促进缺陷界面塑性流变，提高焊合界面结合强度，实现无塑性变形晶粒细化，从而打破强塑性倒置规律，实现铸件强塑性的全面提升，降低铸件受力二次萌生裂纹的风险，提升铸件综合使用性能。
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Figure CN122999981A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of hot working technology of metal materials, specifically relating to a cyclic variable temperature hot isostatic pressing process for K4169 nickel-based high-temperature alloy. Background Technology
[0002] K4169 nickel-based superalloy is a nickel-based precipitation-hardening equiaxed cast superalloy with γ'' phase as the main strengthening phase and γ' phase as the auxiliary strengthening phase. It possesses excellent medium- and high-temperature strength, creep resistance, and corrosion resistance, making it the preferred material for core load-bearing castings in aero-engines.
[0003] Because investment casting is prone to defects such as porosity, micropores, and interdendritic microcracks during solidification, which significantly reduce the strength, plasticity, and fatigue life of castings and fail to meet the stringent service standards of aerospace equipment, the current main treatment for K4169 nickel-based superalloy castings is hot isostatic pressing (HIP). A typical HIP process usually involves holding the casting at a constant temperature of 1160~1180℃ for 2~4 hours, relying on high-temperature and high-pressure plastic rheology to close the pores of the nickel-based superalloy casting. However, prolonged high-temperature holding leads to severe grain coarsening, with the grain size of the nickel-based superalloy casting reaching hundreds of micrometers or millimeters, resulting in a significant reduction in the plasticity and fatigue performance of the casting. Furthermore, relying solely on plastic rheology to weld defects results in a lack of dynamic recrystallization behavior at the defect interface, leading to low interfacial bonding strength. Under stress, the component is prone to re-initiation of cracks, which limits the actual use of the casting.
[0004] Currently, there are some technologies that use segmented heating for hot isostatic pressing and then use composite processes such as forging and rolling to process castings. However, segmented heating is difficult to continuously induce dynamic recrystallization in defect areas, resulting in a weak grain refinement effect and significantly limiting the performance enhancement of castings. Composite processes, on the one hand, require more types of processing steps, which significantly increases both time and economic costs. On the other hand, they cannot perform plastic processing on complex thin-walled or irregularly shaped castings.
[0005] Therefore, it is necessary to provide a cyclic variable temperature hot isostatic pressing process for K4169 nickel-based superalloy to simultaneously achieve casting defect repair, grain refinement, and improve interfacial bonding strength, thereby enhancing the overall performance of K4169 nickel-based superalloy castings. Summary of the Invention
[0006] To overcome the problems in the prior art, this invention applies high-low temperature cyclic hot isostatic pressing to K4169 nickel-based high-temperature alloy castings. By utilizing cyclic thermal stress and temperature gradients to induce dislocation proliferation, dynamic recovery, and dynamic recrystallization at the interfaces of pores and microcracks, this invention eliminates the need for additional treatments such as plastic deformation. This solves problems such as micropores, incomplete welding, weak interface bonding, easy secondary cracking during service, and grain coarsening in castings, achieving simultaneous improvement in the strength and plasticity of the castings, thereby enhancing their overall performance.
[0007] To achieve the above objectives, the present invention is implemented through the following technical solution: This invention proposes a cyclic variable-temperature hot isostatic pressing (HIP) process for K4169 nickel-based superalloy, which includes the following steps: (1) Grind the K4169 nickel-based high-temperature alloy casting to remove sand, oxide scale and gating gates from the surface of the casting, and then perform ultrasonic cleaning and drying.
[0008] (2) In an inert atmosphere, the K4169 nickel-based superalloy casting treated in step (1) is subjected to hot isostatic pressing. During the hot isostatic pressing process, the nickel-based superalloy casting is first heated to the highest temperature T. max Then the nickel-based superalloy casting is cooled to the lowest temperature T. min Then, heat the nickel-based superalloy casting to T. max Cool down to T min Repeat the loop.
[0009] The T max ≤1200℃, the T min ≥900℃.
[0010] (3) After the completion of the repeated cycle of step (2), the nickel-based high-temperature alloy casting is cooled to below 200°C in the furnace, and the pressure is released to remove the nickel-based high-temperature alloy casting.
[0011] Preferably, in step (2), 30℃≤T max -T min ≤200℃.
[0012] Further optimization, 50℃≤T max -T min ≤150℃ Preferably, in step (2), the nickel-based superalloy casting is cooled to T. min Then heat up to T max One cycle consists of 2 to 30 cycles, with a total cycle time of 0.1 to 6 hours.
[0013] Further optimization is performed, with a total of 4 to 20 cycles.
[0014] Preferably, in step (2), the pressure of hot isostatic pressing is 100~200MPa.
[0015] Further optimization is to use a hot isostatic pressing (HIP) pressure of 150-190 MPa.
[0016] Preferably, in step (2), the heating rate is equal to the cooling rate.
[0017] Beneficial effects of the present invention 1. This invention generates periodic thermal stress through cyclic variable-temperature hot isostatic pressing, which promotes plastic rheology at defect interfaces, improves the bonding strength of weld interfaces, and achieves grain refinement without plastic deformation. This breaks the inversion law of strong plasticity, comprehensively improves the strong plasticity of castings, reduces the risk of secondary crack initiation under stress, and enhances the overall performance of castings.
[0018] 2. The castings after cyclic temperature hot isostatic pressing treatment according to the present invention can have an average grain size of at least 43μm, a tensile strength of 1100MPa, a yield strength of 840MPa, an elongation of up to 18%, and a reduction of area of up to 20% or more.
[0019] 3. This invention does not require additional plastic deformation processes such as rolling to refine grains, thus maintaining relatively low time and economic costs. The process is simple, has good controllability, and is suitable for industrial application. Attached Figure Description
[0020] Figure 1 These are comparative images of the defect morphologies of nickel-based superalloy castings from Comparative Example 1 and Examples 1-3 of the present invention, wherein... Figure 1 (a) Figure 1 (a1) are defect morphology diagrams of the nickel-based superalloys in Comparative Example 1. Figure 1 (b) Figure 1 (b1) are all defect morphology images of the nickel-based superalloy of Example 1. Figure 1 (c) Figure 1 (c1) are defect morphology images of the nickel-based superalloy from Example 2. Figure 1 (d) Figure 1 (d1) are all defect morphology images of the nickel-based superalloy in Example 3; Figure 2 The above are statistical histograms of grain structure and grain size of nickel-based superalloy castings from Comparative Examples 1 and Examples 1-3 of this invention. Figure 2 (a) is the IPF diagram of the nickel-based superalloy casting of Comparative Example 1. Figure 2(a1) is the KAM diagram of the nickel-based superalloy casting of Comparative Example 1. Figure 2 (a2) is a grain boundary diagram of the nickel-based superalloy casting of Comparative Example 1. Figure 2 (a3) is a grain size histogram of the nickel-based superalloy casting in Comparative Example 1. Figure 2 (b) is the IPF diagram of the nickel-based superalloy casting of Example 1. Figure 2 (b1) is the KAM diagram of the nickel-based superalloy casting of Example 1. Figure 2 (b2) is a grain boundary diagram of the nickel-based superalloy casting of Example 1. Figure 2 (b3) is a histogram of grain size of the nickel-based superalloy casting of Example 1. Figure 2 (c) is the IPF diagram of the nickel-based superalloy casting of Example 2. Figure 2 (c1) is the KAM diagram of the nickel-based superalloy casting of Comparative Example 1. Figure 2 (c2) is a grain boundary diagram of the nickel-based superalloy casting of Example 2. Figure 2 (c3) is a grain size histogram of the nickel-based superalloy casting of Example 2. Figure 2 (d) is the IPF diagram of the nickel-based superalloy casting of Example 3. Figure 2 (d1) is the KAM diagram of the nickel-based superalloy casting of Example 3. Figure 2 (d2) is a grain boundary diagram of the nickel-based superalloy casting of Example 3. Figure 2 (d3) is a grain size histogram of the nickel-based superalloy casting of Example 3; Figure 3 This is a stress-strain curve diagram of the nickel-based superalloy casting of Comparative Example 1 and Example 3 of the present invention. Figure 4 The stress-strain curves of the nickel-based superalloy castings of Comparative Examples 1, 2, and Example 3 of this invention are shown. Figure 5 This is a schematic diagram of the process flow for Embodiments 1-3 of the present invention. Detailed Implementation
[0021] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited to the content described.
[0022] The nickel-based superalloy castings in the embodiments and comparative examples of this invention are K4169 equiaxed crystal turbine test blocks cast by investment casting. The castings have casting defects such as porosity and micropores.
[0023] Example 1 This embodiment processes the K4169 equiaxed crystal turbine test block using the following method: (1) Pretreatment: The K4169 equiaxed crystal turbine specimen was polished to remove the sand adhering to the surface, and then ultrasonically cleaned with anhydrous ethanol for 30 min and dried at 120℃.
[0024] (2) Loading and vacuuming: Place the K4169 equiaxed crystal turbine specimen into the hot isostatic pressing furnace, vacuum to 0.01 Pa, and then fill with high-purity argon gas (purity ≥99.995%). (3) The hot isostatic pressing furnace is pressurized to 180 MPa and held at that pressure. The K4169 equiaxed crystal turbine specimen is heated to 1160℃ at a heating rate of 10℃ / min, and then cooled to 1020℃ at a cooling rate of 10℃ / min. A total of 4 cycles are performed, with a total cycle time of approximately 2 hours (e.g., Figure 5 (As shown).
[0025] (4) After the cycle is completed, the K4169 equiaxed crystal turbine test block is cooled to 200°C with the furnace, the pressure is released, and the K4169 equiaxed crystal turbine test block is taken out of the furnace.
[0026] The test sample obtained in this embodiment is denoted as HIP1.
[0027] Example 2 This embodiment processes the K4169 equiaxed crystal turbine test block using the following method: (1) Pretreatment: The K4169 equiaxed crystal turbine specimen was polished to remove the sand adhering to the surface, and then ultrasonically cleaned with anhydrous ethanol for 30 min and dried at 120℃.
[0028] (2) Loading and vacuuming: Place the K4169 equiaxed crystal turbine specimen into the hot isostatic pressing furnace, vacuum to 0.01 Pa, and then fill with high-purity argon gas (purity ≥99.995%). (3) The hot isostatic pressing furnace is pressurized to 180 MPa and held at that pressure. The K4169 equiaxed crystal turbine specimen is heated to 1160℃ at a heating rate of 10℃ / min, and then cooled to 1100℃ at a cooling rate of 10℃ / min. A total of 10 cycles are performed, with a total cycle time of 2 hours (e.g., Figure 5 (As shown).
[0029] (4) After the cycle is completed, the K4169 equiaxed crystal turbine test block is cooled to 200°C with the furnace, the pressure is released, and the K4169 equiaxed crystal turbine test block is taken out of the furnace.
[0030] The test sample obtained in this embodiment is denoted as HIP2.
[0031] Example 3 This embodiment processes the K4169 equiaxed crystal turbine test block using the following method: (1) Pretreatment: The K4169 equiaxed crystal turbine specimen was polished to remove the sand adhering to the surface, and then ultrasonically cleaned with anhydrous ethanol for 30 min and dried at 120℃.
[0032] (2) Loading and vacuuming: Place the K4169 equiaxed crystal turbine specimen into the hot isostatic pressing furnace, vacuum to 0.01 Pa, and then fill with high-purity argon gas (purity ≥99.995%). (3) The hot isostatic pressing furnace is pressurized to 180 MPa and held at that pressure. The K4169 equiaxed crystal turbine specimen is heated to 1160℃ at a heating rate of 10℃ / min, and then cooled to 1100℃ at a cooling rate of 10℃ / min. A total of 15 cycles are performed, with a total cycle time of 3 hours (e.g., Figure 5 (As shown).
[0033] (4) After the cycle is completed, the K4169 equiaxed crystal turbine test block is cooled to 200°C with the furnace, the pressure is released, and the K4169 equiaxed crystal turbine test block is taken out of the furnace.
[0034] The test sample obtained in this embodiment is denoted as HIP3.
[0035] Example 4 This embodiment uses the same method as in Embodiment 1, the difference being that: in this embodiment, the hot isostatic pressure is 200 MPa, T max =1200℃, T min =1000℃, with 2 cycles and a total cycle time of approximately 0.5h, then during the cyclic temperature-variable hot isostatic pressing process, the heating and cooling rates are approximately 27℃ / min.
[0036] In this embodiment, the casting defects inside the casting are basically welded together, and the grain size is significantly finer compared to the as-cast state; however, in this embodiment, a higher T is used. max The cyclic temperature difference and rapid heating and cooling cause a certain thermal shock to the casting. The improvement in the overall mechanical properties of this embodiment is relatively low compared to that of embodiment 3, and it is suitable for small and simple casting trial production.
[0037] Example 5 This embodiment uses the same method as Embodiment 1, the difference being that: in this embodiment, the hot isostatic pressure is 100 MPa, T max =930℃, T min =900℃, the cycle period is 30, the total cycle time is 6h, then the heating and cooling rate during the cyclic temperature-variable hot isostatic pressing process is 5℃ / min.
[0038] In this embodiment, a lower T is used. minThe shallow defects on the surface of the casting are closed, but the low pressure and temperature difference lead to a decrease in cyclic thermal stress, a weak degree of dynamic recrystallization, and a limited effect on grain refinement. The improvement in mechanical properties is relatively limited compared to Example 3.
[0039] Comparative Example 1 The comparative sample is an untreated K4169 equiaxed crystal turbine specimen.
[0040] Comparative Example 2 This comparative example uses the same method as Example 3 to process the K4169 equiaxed crystal turbine specimen. The difference is that no pressure is applied during the processing of this example, and only cyclic temperature change treatment is performed.
[0041] The defect morphology of the experimental samples in Examples 1-3 and Comparative Example 1 was observed, and the results are as follows: Figure 1 As shown.
[0042] pass Figure 1 It can be seen that there are no obvious defects after cyclic hot isostatic pressing, only traces of defect healing, indicating that the defects have been healed and eliminated. The cyclic hot isostatic pressing of this invention has the effect of effectively eliminating defects.
[0043] The grain structure and grain size of the experimental samples in Examples 1-3 and Comparative Example 1 were statistically analyzed, and the results are as follows: Figure 2 As shown.
[0044] pass Figure 2 It can be seen that the average grain size of the experimental samples in Examples 1-3 is significantly lower than that in Comparative Example 1. The average grain size of Example 3 is only 43 μm, which proves that the present invention continuously stimulates dynamic recrystallization at the defect interface through alternating high and low temperature cycles, and the newly generated fine equiaxed crystals divide the original coarse grains, so as to achieve grain refinement without the need for plastic deformation processes such as forging and rolling.
[0045] pass Figure 2 (a1~d1) It can be seen that as the cyclic hot isostatic pressing continues, the density of geometrically necessary dislocations inside the alloy decreases continuously; the dislocation level is even lower in the grain refinement region, indicating that the dynamic recrystallization process consumes the stored dislocations in the matrix.
[0046] pass Figure 2 (a2~d2) It can be seen that cyclic hot isostatic pressing promotes the transformation of small-angle grain boundaries into large-angle grain boundaries, and the proportion of large-angle grain boundaries increases significantly, providing direct evidence for dynamic recrystallization occurring inside the sample.
[0047] For the polar tensile tests of the experimental samples in Examples 1-3 and Comparative Example 1, two sets of parallel tests were performed for each experimental sample, and the results are as follows. Figure 3 As shown, through Figure 3The quantitative performance data of the experimental samples were obtained, as shown in Table 1.
[0048] Table 1 As shown in Table 1, the tensile strength of the sample in Example 1 was 1073±4 MPa, the yield strength was 839.5±3.5 MPa, the elongation was 12.4±0.3%, and the reduction of area was 14.5±0.2%; the tensile strength of the sample in Example 2 was 1100.5±8.5 MPa, the yield strength was 849.5±10.5 MPa, the elongation was 14.55±1.05%, and the reduction of area was 15.8±0.4%; the tensile strength of the sample in Example 3 was 1102±9 MPa, the yield strength was 841±9 MPa, the elongation was 18.5±1.4%, and the reduction of area was 22.95±1.35%; and the tensile strength of the sample in Comparative Example 1 was 1021±20 MPa, the yield strength was 769.5±6.5 MPa, the elongation was 11.25±0.85%, and the reduction of area was 13.35±0.15%. The tensile strength, yield strength, elongation, and reduction of area of the samples in Examples 1-3 were significantly improved compared to Comparative Example 1, especially Example 3, which showed the most significant improvement. Therefore, this invention can effectively break the inverse law of strength and plasticity, achieve synergistic improvement of strength and plasticity, significantly improve the fatigue life and fracture resistance of castings, and give castings better comprehensive performance.
[0049] Three parallel tensile tests were conducted on the sample of Comparative Example 2, and the results are as follows: Figure 4 As shown, through Figure 4 The quantitative performance data of the comparative example 2 sample can be obtained, as shown in Table 2.
[0050] Table 2 As can be seen from Table 2, the tensile strength, elongation, and reduction of area of the sample in Comparative Example 2 all decreased compared to Comparative Example 1, proving that only high and low temperature cycling was performed, and the synergistic effect of pressure was lost, resulting in grain coarsening and further deterioration of the sample performance.
[0051] In summary, this invention obtains K4169 nickel-based high-temperature alloy castings with excellent comprehensive performance through a process that is highly adaptable, simple, low-cost, and has high stability in mass production, fully meeting the stringent requirements of high-pressure turbine disks and blades for aero-engines.
[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.
Claims
1. A cyclic variable-temperature hot isostatic pressing process for K4169 nickel-based superalloy, characterized in that: The cyclic variable-temperature hot isostatic pressing process includes the following steps: (1) Grind the K4169 nickel-based high-temperature alloy casting, and then perform ultrasonic cleaning and drying. (2) In an inert atmosphere, the K4169 nickel-based superalloy casting treated in step (1) is subjected to hot isostatic pressing. During the hot isostatic pressing process, the nickel-based superalloy casting is first heated to the highest temperature T. max Then the nickel-based superalloy casting is cooled to the lowest temperature T. min Then, heat the nickel-based superalloy casting to T. max Cool down to T min Repeat the loop; The T max ≤1200℃, the T min ≥900℃; (3) After the completion of the repeated cycle of step (2), the nickel-based high-temperature alloy casting is cooled to below 200°C in the furnace, and the pressure is released to remove the nickel-based high-temperature alloy casting.
2. The cyclic variable-temperature hot isostatic pressing process for K4169 nickel-based high-temperature alloy according to claim 1, characterized in that: In step (2), 30℃≤T max -T min ≤200℃.
3. The cyclic variable-temperature hot isostatic pressing process for K4169 nickel-based high-temperature alloy according to claim 1, characterized in that: In step (2), the nickel-based superalloy casting is cooled to T. min Then heat up to T max One cycle consists of 2 to 30 cycles, with a total cycle time of 0.1 to 6 hours.
4. The cyclic variable-temperature hot isostatic pressing process for K4169 nickel-based high-temperature alloy according to claim 1, characterized in that: In step (2), the pressure of hot isostatic pressing is 100~200MPa.
5. The cyclic variable-temperature hot isostatic pressing process for K4169 nickel-based high-temperature alloy according to claim 1, characterized in that: In step (2), the heating rate is equal to the cooling rate.