Age hardening type high-temperature alloy hot-rolled bar and grain size control method thereof

Abstract

The invention relates to the technical field of high-temperature alloy material processing, in particular to an age hardening type high-temperature alloy hot-rolled bar and a grain size control method thereof.The age hardening type high-temperature alloy hot-rolled bar comprises, by weight, 0.03%-0.06% of C, 20%-25% of Cr, 0.60%-0.8% of Al, 2.0%-2.4% of Ti, smaller than or equal to 0.8% of Fe, smaller than or equal to 0.01% of B, smaller than or equal to 0.02% of Ce, smaller than or equal to 0.65% of Si, smaller than or equal to 0.2% of Mn, smaller than or equal to 0.07% of Cu and the balance Ni and inevitable impurities. According to the method for reasonably blending the components of the age hardening type high-temperature alloy hot-rolled bar and controlling the grain size, the residual stress in the hot-rolled bar can be eliminated, the hot-rolled bar with the required grain size can be obtained, and the method is particularly suitable for the age hardening type high-temperature alloy hot-rolled bar with the finished product size not larger than 40 mm.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-temperature alloy material processing, in particular to an aging hardening type high-temperature alloy hot-rolled bar and a grain size control method thereof, and especially to a method for controlling the grain size of a certain nickel-based high-temperature alloy hot-rolled bar by synergistically controlling residual stress elimination and phase transformation behavior, and the method is especially suitable for the preparation of high-performance high-temperature alloy bars for aero-engines. BACKGROUND

[0002] The aging hardening type high-temperature alloy has been widely used in the fields of aviation, aerospace, energy and the like due to its excellent high-temperature mechanical properties and oxidation resistance and corrosion resistance. China began to imitate the alloy in the 1980s, and developed and produced forged pieces for aero-engines. The grain structure of the forged pieces is relatively uniform, and the grain size is in the range of 2-6 levels after standard heat treatment, and the high-temperature tensile plasticity at 750°C is about 15%. In recent years, with the development of high-tech fields such as aerospace, national defense and military industry, and ocean development, in order to meet the use requirements of high-temperature fasteners, small-size rolled bars of specific aging hardening type alloys have been produced in large quantities, especially the finished size of no more than 40 mm. However, due to the high alloying degree of the alloy, the processing performance is poor, and the grain size of the rolled bar produced after standard heat treatment is often not qualified, resulting in low plasticity. Therefore, how to obtain high-temperature alloy hot-rolled bars meeting the requirements and effectively control the grain size of the high-temperature alloy hot-rolled bars has become a technical problem to be solved.

[0003] Currently, the research on the control of the grain size of rolled bars is more focused on the adjustment of the rolling process and the optimization of the composition and structure of the original bar stock. For example, the invention patent with the application number 202411643019.8 "Small-specification ultra-high-strength steel hot-rolled bar blank for fasteners" specifically includes the following steps: first, the Φ120mm-Φ160mm specification blank is formed into a Φ10.5mm-Φ12.5mm specification blank after being heat treated and rolled multiple times at a specified temperature, wherein the deformation amount of the heat treatment and rolling process is 70%-90%; then, the Φ10.5mm-Φ12.5mm specification blank is subjected to normalizing heat treatment and then high-temperature tempering heat treatment; finally, the Φ10.5mm-Φ12.5mm specification blank is machined into a Φ10mm specification finished bar. By controlling the heating temperature, the finish rolling temperature and the temperature rise of the bar core during rolling, the grain size of the finished bar (Φ10mm specification bar blank) is controlled at 8.5 level. The invention patent with the application number 202310477727.8 "Preparation method of fine-grained high-strength GH4720Li alloy small-specification bar" specifically includes: preparing a GH4720Li alloy blank; pretreating the GH4720Li alloy blank; hot rolling the GH4720Li alloy blank to obtain a GH4720Li alloy bar; and using the residual heat after hot rolling to heat straighten the GH4720Li alloy bar to obtain a GH4720Li alloy small-specification bar. The GH4720Li alloy small-specification bar prepared by the method has a diameter of 15mm-20mm, a grain size of 10 13 level, a room temperature tensile strength greater than 1620MPa, and a 650℃ tensile strength greater than 1450MPa, and can be used to make high-performance high-temperature alloy blades for aircraft engines. However, the adjustment of the rolling process and the optimization of the composition and structure of the original bar stock cannot well meet the specific needs of grain size in different scenarios without adjusting the existing production line.

[0004] Therefore, the existing technology still needs to be improved. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application provides a time-hardening high-temperature alloy hot-rolled bar and a grain size control method thereof. The method performs recrystallization annealing before standard heat treatment of the hot-rolled bar to eliminate residual stress and maintain grain size. The method first prepares a blank required for hot rolling by rationalizing alloy composition and its ratio, and performs heat preservation treatment on the blank. Then, the blank is rolled by a 550 / 280 rolling mill to obtain a hot-rolled bar of the required size. Subsequently, the residual stress inside the hot-rolled bar is eliminated by recrystallization pretreatment, and the hot-rolled bar is subjected to standard heat treatment to obtain a hot-rolled bar of the required grain size. In summary, the present application realizes the control of the grain size of the time-hardening high-temperature alloy hot-rolled bar through the above steps.

[0006] Specifically, according to a first aspect of the present application, a kind of age hardening type high-temperature alloy hot-rolled bar is provided, comprising the following weight percentage components: C: 0.03%~0.06%, Cr: 20%~25%, Al: 0.60%~0.8%, Ti: 2.0%~2.4%, Fe≤0.8%, B≤0.01%, Ce≤0.02%, Si≤0.65%, Mn≤0.2%, Cu≤0.07%, the rest is Ni and unavoidable impurities, the average grain size of the age hardening type high-temperature alloy hot-rolled bar is 2~6 grade, diameter≤ 40mm, elongation A≥5%, reduction of area Z≥10% and tensile strength R m ≥750MPa.

[0007] According to a second aspect of the present application, a grain size control method of the age hardening type high-temperature alloy hot-rolled bar is provided, comprising the following steps: S10. obtaining the billet required for the age hardening type high-temperature alloy hot-rolled bar, holding the billet at a first predetermined temperature for a first predetermined time, then rough rolling the billet to obtain an intermediate billet, finishing the intermediate billet, and then finishing rolling to obtain a hot-rolled bar of a specific size; S20. recrystallization annealing pretreatment of the hot-rolled bar of a specific size at a second predetermined temperature for a second predetermined time, and then air cooling to room temperature, wherein the second predetermined temperature and the second predetermined time meet the requirements of low temperature and long time or high temperature and short time; and S30. standard heat treatment of the air-cooled hot-rolled bar to obtain the age hardening type high-temperature alloy hot-rolled bar.

[0008] In an embodiment of the present application, in step S20, under the requirement of low temperature and long time, the second predetermined temperature is 1000℃~1040℃, and the second predetermined time is 4h~10h.

[0009] In an embodiment of the present application, in step S20, under the requirement of high temperature and short time, the second predetermined temperature is 1120℃~1160℃, and the second predetermined time is 0.5h~2h.

[0010] In an embodiment of the present application, characterized in that, in step S10, a vacuum induction and vacuum consumable melting process is used to obtain an electrode rod of age hardening high-temperature alloy, and then homogenization treatment, open billet forging and precision forging are carried out to obtain the billet required for the age hardening type high-temperature alloy hot-rolled bar, the diameter of the billet is 60mm~ 90mm.

[0011] In the embodiment of the present application, in step S10, the first predetermined temperature is 1000℃-1200℃, and the first predetermined time is 1h-4h.

[0012] In the embodiment of the present application, in step S10, the first predetermined temperature is 1000℃-1200℃, and the first predetermined time is 1h-4h. 550 rolling mill is used to rough roll the blank, wherein the rough rolling has a rough rolling temperature ≥1000℃, a final rolling temperature ≥900℃, and 6-8 rolling passes, to obtain an intermediate blank with a diameter of 50mm 60mm.

[0013] In the embodiment of the present application, in step S10, the finishing includes peeling or polishing treatment on the intermediate blank.

[0014] In the embodiment of the present application, in step S10, the first predetermined temperature is 1000℃-1200℃, and the first predetermined time is 1h-4h. 280 rolling mill is used to finish roll the finished intermediate blank, wherein the finish rolling has a finish rolling temperature ≥1000℃, a final rolling temperature ≥900℃, and 8-10 rolling passes, to obtain a hot-rolled bar ≤ 40mm.

[0015] In the embodiment of the present application, in step S30, the heat treatment system of the standard heat treatment is: 1100℃-1200℃ for 1h-10h, air cooling; 900℃-1100℃ for 1h-10h, air cooling; and 600℃-1000℃ for 1h-24h, air cooling.

[0016] The grain size control method of the age hardening type high-temperature alloy hot-rolled bar disclosed in the present application first prepares the blank required for the hot-rolled bar, and performs heat preservation treatment on the blank, and then performs rolling through 550 / 280 rolling mills to obtain the hot-rolled bar with the required size. Subsequently, through the method of recrystallization pretreatment, the residual stress inside the hot-rolled bar is eliminated, and then the hot-rolled bar is subjected to standard heat treatment to obtain the hot-rolled bar with the required grain size. Through the above steps, the grain size control of the specific type of age hardening type high-temperature alloy hot-rolled bar disclosed in the present application can be realized, and the demand for grain size can be met (for example, the age hardening type high-temperature alloy hot-rolled bar with an average grain size of 2-6 levels can be obtained). In addition, the method disclosed in the present application is especially suitable for the age hardening type high-temperature alloy hot-rolled bar with a size not greater than 40mm.

[0017] The age hardening type high-temperature alloy hot-rolled bar and the grain size control method thereof proposed in the present application are very necessary, and such method has important promoting effect in promoting subsequent production and processing and improving efficiency. At the same time, it has important significance for energy saving and emission reduction and reducing enterprise production cost. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 shows the flow chart of the grain size control method of the age hardenable high-temperature alloy hot-rolled bar provided by the present application; Figure 2 is the microstructure diagram after standard heat treatment directly on the hot-rolled bar; Figure 3 is the microstructure diagram after standard heat treatment after the hot-rolled bar is kept at 1000℃~1040℃ for 4h~10h and air-cooled; Figure 4 is the microstructure diagram after standard heat treatment after the hot-rolled bar is kept at 1000℃~1040℃ for more than 10h and air-cooled; Figure 5 is the microstructure diagram after standard heat treatment after the hot-rolled bar is kept at 1000℃~1040℃ for less than 4h and air-cooled; Figure 6 is the microstructure diagram after standard heat treatment after the hot-rolled bar is kept at 960℃~980℃ for 6h~10h and air-cooled; Figure 7 is the microstructure diagram after standard heat treatment after the hot-rolled bar is kept at 960℃~980℃ for more than 10h and air-cooled; Figure 8 is the microstructure diagram after standard heat treatment after the hot-rolled bar is kept at 960℃~980℃ for less than 6h and air-cooled; Figure 9 is the microstructure diagram after standard heat treatment after the hot-rolled bar is kept at 1060℃~1080℃ for 1h~2h and air-cooled; Figure 10 is the microstructure diagram after standard heat treatment after the hot-rolled bar is kept at 1060℃~1080℃ for more than 2h and air-cooled; Figure 11 is the microstructure diagram after standard heat treatment after the hot-rolled bar is kept at 1120℃~1160℃ for 0.5h~2h and air-cooled; Figure 12 is the microstructure diagram after standard heat treatment after the hot-rolled bar is kept at 1120℃~1160℃ for more than 2h and air-cooled; Figure 13 is the microstructure diagram after standard heat treatment after the hot-rolled bar is kept at 1120℃~1140℃ for less than 0.5h and air-cooled; Figure 14 is the microstructure diagram after standard heat treatment after the hot-rolled bar is kept at 1160℃ for less than 0.5h and air-cooled; Figure 15is a schematic diagram of the microstructure of a hot-rolled bar after standard heat treatment after being kept at 1100℃ for 0.5h-2h and air-cooled; Figure 16 is a schematic diagram of the microstructure of a hot-rolled bar after standard heat treatment after being kept at 1100℃ for more than 2h and air-cooled; Figure 17 is a schematic diagram of the microstructure of a hot-rolled bar after standard heat treatment after being kept at 1100℃ for less than 0.5h and air-cooled; Figure 18 is a schematic diagram of the microstructure of a hot-rolled bar after standard heat treatment after being kept at 1180℃-1200℃ for different time and air-cooled; Figure 19 is a schematic diagram of the microstructure of a hot-rolled bar after standard heat treatment after being kept at 1020℃ for 4h and air-cooled; Figure 20 is a schematic diagram of the microstructure of a hot-rolled bar after standard heat treatment after being kept at 1040℃ for 6h and air-cooled; and Figure 21 is a schematic diagram of the microstructure of a hot-rolled bar after standard heat treatment after being kept at 1140℃ for 1h and air-cooled. DETAILED DESCRIPTION

[0019] It should be understood that the embodiments of the application shown in the example embodiments are only illustrative. Although only a few embodiments of the application are described in detail, those skilled in the art can easily appreciate that various modifications are possible without departing from the teachings of the subject matter of the application. Accordingly, all such modifications should be included within the scope of the application. Other substitutions, modifications, changes and omissions can be made to the design, operating conditions and parameters of the following example embodiments without departing from the spirit of the application.

[0020] In view of the deficiencies in the prior art, the present application provides, in one aspect, an age-hardened high-temperature alloy hot-rolled bar, which comprises the following components by weight percentage: C: 0.03%-0.06%, Cr: 20%-25%, Al: 0.60%-0.8%, Ti: 2.0%-2.4%, Fe≤0.8%, B≤0.01%, Ce≤0.02%, Si≤0.65%, Mn≤0.2%, Cu≤0.07%, the rest being Ni and unavoidable impurities, the average grain size of the age-hardened high-temperature alloy hot-rolled bar being 2-6 grades (including the end point value), the diameter being ≤ 40mm, the elongation A≥5%, the reduction of area Z≥10% and the tensile strength R m ≥750MPa.

[0021] The inventor found in practice that the grain size control core contradiction of the hot-rolled bar above lies in that the accumulated residual stress in the hot-rolling process and the phase transformation behavior in the subsequent heat treatment are coupled with each other, and jointly determine the growth, uniformity and final size of the grain.

[0022] For the residual stress, in the conventional alloy hot-rolling process (especially for the multi-pass rough rolling + finishing rolling of small size bars D≤40mm), the metal is prone to severe plastic deformation, which causes the internal atomic arrangement to be dislocated and distorted, resulting in the formation of significant residual internal stress (mainly shear stress and thermal stress). If the standard heat treatment (1100℃~1200℃ solid solution + aging) is directly carried out, then under the high temperature environment, the residual stress will become the "additional driving force" for the grain boundary movement, promoting the grain to grow rapidly along the stress concentration area, resulting in uneven grain size (mixed crystal, such as the grain size 1~8 level when no pre-treatment as mentioned below in the invention). In addition, stress concentration will also inhibit the uniformity of dynamic recrystallization, forming local coarse grain or unrecrystallized structure, ultimately leading to substandard plasticity (elongation A only 3%) and strength.

[0023] For the phase transformation behavior, the core of the phase transformation of the alloy is static recrystallization phase transformation (the transformation of the deformed structure after hot-rolling to equiaxed crystal structure), and the phase transformation degree, nucleation rate and grain growth rate directly determine the final grain size.

[0024] If only the residual stress is eliminated without regulating the phase transition, it will lead to insufficient or excessive recrystallization; if only the phase transition is regulated without eliminating the residual stress, the abnormal driving force of grain boundary migration at high temperature is easy to cause abnormal grain growth. The present application can realize the accurate control of grain size (2-6 levels) by synergistically controlling the "residual stress elimination" and "phase transition behavior regulation", while ensuring that the mechanical properties meet the standards. Overall, on the one hand, the present application realizes the efficient elimination of residual stress through "recrystallization annealing pretreatment" (low temperature long time / high temperature short time process): during the pretreatment process, the alloy is kept at 1000-1160 DEG C, and the atoms obtain sufficient diffusion energy, and the residual stress is released through "stress relaxation" and "static recrystallization" (stress relaxation: atoms migrate along lattice defects, relieve lattice distortion, and reduce internal stress level; static recrystallization: the deformed structure (dislocation dense area) after hot rolling forms new stress-free equiaxed grains through nucleation and growth, replacing the original stress-rich deformed grains, and fundamentally eliminating the residual stress). The present application verifies the technical effect of the present application through examples, for example, in Example 3, "air cooling" is combined with appropriate holding time, the stress is fully eliminated, and the average grain size is 3-5 (qualified), which proves that the elimination of residual stress is the premise of grain size control. On the other hand, the present application realizes the directional control of phase transition behavior by accurately regulating the "temperature-time" parameters of the pretreatment. The regulation target of the phase transition behavior of the present application is as follows: phase transition sufficiency: ensure that the hot rolled deformed structure is completely recrystallized, and avoid the residual of coarse deformed grains which are not recrystallized; phase transition moderation: inhibit the excessive growth of recrystallized grains, and avoid the formation of 1-2 level coarse grains (such as when the pretreatment temperature is >1040 DEG C or the holding time is >10h, the grains grow excessively); phase transition uniformity: ensure that the nucleation rate of recrystallized grains is consistent, and avoid the excessive difference of local grain size (mixed grains). The regulation mechanism of the phase transition behavior of the present application is as follows: the present application realizes the accurate regulation of phase transition through two process paths, and the essence is to balance the "recrystallization nucleation rate" and "grain growth rate" through temperature and time synergistic control: Path 1: low temperature long time pretreatment (1000-1040 DEG C, 4-10h) Under low temperature environment, the recrystallization nucleation rate is low, but long time holding can ensure sufficient nucleation; at the same time, low temperature inhibits the grain growth rate, avoiding the excessive coarsening of recrystallized grains. At this time, the phase transition is mainly "slow nucleation, slow growth", and finally forms 3-5 level uniform fine grains.

[0025] Critical condition: when the holding time is <4h, the nucleation is insufficient, the residual deformed grains are left, and the average grain size is finer than 6 levels (unqualified); when the holding time is >10h, the grain growth is dominant, and the average grain size is reduced to 1-2 levels (unqualified).

[0026] Path 2: high temperature short time pretreatment (1120-1160 DEG C, 0.5-2h) Under high temperature environment, the recrystallization nucleation rate is significantly improved, and sufficient nucleation can be achieved by short-time holding; at the same time, the holding time is strictly controlled (≤2h) to avoid rapid grain growth at high temperature. At this time, the phase transition is mainly "fast nucleation and limited growth", and finally uniform grains of 2-5 levels are formed.

[0027] Critical condition: when the holding time is <0.5h, the nucleation is insufficient, and the grain size is finer than 6 levels (unqualified). When the holding time is >2h, the high temperature accelerates the grain growth, and the grain size is reduced to 1-2 levels (coarser than 2 levels, unqualified).

[0028] In short, the present application is to fully study the coupling relationship between phase transition and residual stress elimination, so that "residual stress elimination" and "recrystallization phase transition" occur synchronously and promote each other during high-temperature pretreatment. The release of residual stress reduces the lattice distortion energy, provides a more stable thermodynamic environment for recrystallization nucleation, and improves the nucleation uniformity; the stress-free equiaxed grains formed by recrystallization phase transition further block the transmission and concentration of residual stress, ensuring complete stress elimination. The two form a positive cycle of "stress release → promote phase transition uniformity → perfect phase transition → strengthen stress elimination", avoiding the loss of control of grain size caused by single treatment.

[0029] The above principles and effects are fully embodied in the grain size control method of the age-hardening high-temperature alloy hot-rolled bar provided in the second aspect of the present application. The method can be used to manufacture the age-hardening high-temperature alloy hot-rolled bar as described in the present application, and can effectively control the average grain size of the hot-rolled bar in the required range (for example, the average grain size is 2-6 levels). As shown in the following formula (I), the method comprises the following steps: Figure 1 S10. Obtain the required billet of the age-hardening high-temperature alloy hot-rolled bar, hold the billet at a first predetermined temperature for a first predetermined time, then perform rough rolling on the billet to obtain an intermediate billet, and then perform finishing on the intermediate billet, and then perform finishing rolling to obtain a hot-rolled bar of a specific size; S20. Perform recrystallization annealing pretreatment on the hot-rolled bar of a specific size at a second predetermined temperature for a second predetermined time, and then air cool to room temperature, wherein the second predetermined temperature and the second predetermined time meet the requirements of low temperature and long time or high temperature and short time; and S30. Perform standard heat treatment on the air-cooled hot-rolled bar to obtain the age-hardening high-temperature alloy hot-rolled bar.

[0030] ​In an embodiment of the present application, in step S10, first, a vacuum induction + vacuum consumable melting process is adopted to obtain the electrode rod of the age hardening type high-temperature alloy, and then a processing mode of homogenization, blooming by a forging machine and finish forging into a material is adopted to obtain the billet required for the age hardening type high-temperature alloy hot-rolled rod. In an embodiment, the diameter of the billet required for the age hardening type high-temperature alloy hot-rolled rod satisfies 60mm 90mm.

[0031] In an embodiment of the present application, in step S10, the first predetermined temperature is 1000℃-1200℃, and the first predetermined time is 1h-4h. That is, after obtaining the required billet, the billet is kept at 1000℃-1200℃ for 1h-4h to reduce the deformation resistance in the alloy, improve the plasticity of the alloy and promote the dynamic recrystallization of the alloy. Then 550 rolling mill is used to coarsely roll the billet, wherein the coarsely rolling open rolling temperature is ≥1000℃, the coarsely rolling final rolling temperature is ≥900℃, the coarsely rolling rolling pass is 6-8 passes, and an intermediate billet with a diameter of 50mm 60mm is obtained. Then the intermediate billet is finished, wherein the finishing includes skinning or polishing treatment of the intermediate billet. Then 280 rolling mill is used to finish rolling the billet, wherein the finish rolling open rolling temperature is ≥1000℃, the finish rolling final rolling temperature is ≥900℃, the finish rolling rolling pass is 8-10 passes, and a hot-rolled rod with a diameter of ≤ 40mm is obtained.

[0032] After obtaining the hot-rolled rod with a predetermined size of a specific size, the conventional practice of the prior art is to then perform standard heat treatment, that is, the following heat treatment system is adopted: 1100℃-1200℃ for 1h-10h, air cooling; 900℃-1100℃ for 1h-10h, air cooling; and 600℃-1000℃ for 1h-24h, air cooling. As Figure 2 the microstructure diagram of the hot-rolled rod obtained after the standard heat treatment after finish rolling, it can be clearly seen from the metallographic diagram that, due to the direct standard heat treatment of the hot-rolled rod, the grain size difference under the microscope is extremely large, there is a clear “mixed crystal” phenomenon (that is, large and small grains are mixed), the grain size distribution range is 1-8 levels, the elongation A is 3%, the reduction of area Z is 7.5%, and the tensile strength Rm is 640MPa, which does not satisfy the average grain size of the age hardening type high-temperature alloy hot-rolled rod provided by the present application is 2-6 levels, the elongation A is ≥5%, the reduction of area Z is ≥10% and the tensile strength R mThe inventors found that the reason for the unqualified grain size is that the hot-rolled bar has a large residual stress, so that the driving force for grain boundary movement is large during the high-temperature solid solution treatment, which promotes abnormal grain growth.

[0033] To prevent the grain growth of the hot-rolled bar during the high-temperature solid solution stage, the present application creatively proposes to perform recrystallization annealing pretreatment before the standard heat treatment. As described above, the purpose of this is that after the recrystallization annealing pretreatment, the metal inside is relaxed, and the stress stored in the alloy is released, thereby reducing the driving force for grain boundary movement during the high-temperature solid solution heat treatment, and reducing the probability of abnormal grain growth of the hot-rolled bar after the solid solution treatment.

[0034] Based on this, the grain size control method of the present application adds step S20 between step S10 and step S30, i.e. the process of performing recrystallization annealing pretreatment on the hot-rolled bar to eliminate the residual stress inside the hot-rolled bar, and then performing the standard heat treatment of step S30.

[0035] To eliminate the residual stress of the alloy while keeping the grain size of the alloy at a certain level, the alloy is kept at 960℃, 980℃, 1000℃, 1020℃, 1040℃, 1060℃, 1080℃ for 1h, 2h, 4h, 6h, 8h, 10h, 12h, 16h, respectively, and then subjected to the standard heat treatment of step S30. Table 1 shows the average grain size of the hot-rolled bar after the low-temperature long-time pretreatment + standard heat treatment.

[0036] Table 1 Average grain size of hot-rolled bar after low-temperature long-time pretreatment + standard heat treatment

[0037] As can be seen from Table 1, when the second predetermined temperature, i.e. the recrystallization annealing pretreatment temperature, is 1000℃-1040℃, the second predetermined time, i.e. the recrystallization annealing holding time, is 4h-10h, and the air cooling, the average grain size of the alloy is in the range of 2-5, which meets the average grain size requirement of the present application, and the elongation, the reduction of area and the tensile strength also meet the requirements. Figure 3 Typically, after the "low-temperature long-time" recrystallization pretreatment defined in the present application, the grain size is uniform and consistent, there is no mixed crystal phenomenon, the grain size is concentrated in the range of 2-5 (including the end point value), which fully meets the average grain size requirement (2-6) of the present application.

[0038] In comparison, under the same conditions or processes, when the second predetermined temperature is 1000-1040℃, the second predetermined time is greater than 10h, and air cooling is used, the average grain size of the alloy is between 1 and 2, but does not reach 2, and does not meet the average grain size requirement of the present application, as shown in Figure 4 . Figure 4 The alloy shown is "low-temperature pretreatment", but the holding time is too long (more than 10h), resulting in excessive grain growth, overall size is coarse, and the grain size is between 1 and 2 (coarser than 2), which does not meet the requirements. In comparison Figure 3 , it can be seen that the overall grain size is "much larger" and is not uniform. Figure 3

[0039] In comparison, under the same conditions or processes, when the second predetermined temperature is 1000-1040℃, the second predetermined time is less than 4h, and air cooling is used, the average grain size of the alloy is between 6 and 9, but is finer than 6, which does not meet the average grain size requirement of the present application, as shown in Figure 5 . Figure 5 The alloy shown is "low-temperature pretreatment", but the holding time is less than 4h, and the residual stress is not completely eliminated, resulting in fine grains and local non-uniformity, and the grain size is finer than 6, which does not meet the requirements. In comparison Figure 3 , the overall grain size is "much finer" and the grain size in some areas is inconsistent. Figure 3

[0040] In comparison, under the same conditions or processes, when the second predetermined temperature is 960-980℃, the second predetermined time is 6-10h, and air cooling is used, the average grain size of the alloy is 2-6, but there are large-size grains with a grain size of 1 in some areas, which does not meet the average grain size requirement of the present application, as shown in Figure 6 . For the alloy shown in Figure 6 , the pretreatment temperature is lower than the lower limit of 1000℃ defined in the present application, although the holding time is sufficient, most of the grains meet the 2-6 level, and 1-level large grains (mixed crystals) appear locally, which does not meet the requirements.

[0041] In comparison, under the same conditions or processes, when the second predetermined temperature is 960-980℃, the second predetermined time is greater than 10h, and air cooling is used, the average grain size of the alloy is between 1 and 2, but does not reach 2 (i.e., coarser than 2), which does not meet the average grain size requirement of the present application, as shown in Figure 7 . For the alloy shown in Figure 7 , the treatment temperature is low and the holding time is too long, resulting in severe grain growth, the overall grain size is 1-2 (coarser than 2), and there is no uniformity, which does not meet the requirements. The overall grain size is "abnormally coarse", and there are no small grains, which is consistent with Figure 4 .​​

[0042] In comparison, when the second predetermined temperature is 960-980℃, the second predetermined time is less than 6h, and air cooling is used, the average grain size of the alloy is between 6-10, but is finer than 6, which does not meet the requirement of the average grain size according to the present application, as shown in Table 2. For the alloy shown in Table 2, the processing temperature is too low and the holding time is insufficient, the residual stress is not eliminated, the grain size is too fine and disordered, and the grain size is finer than 6, which does not meet the requirement. The overall grain size is "too fine and uneven", which is consistent with the defect. Figure 8 Figure 8 For the alloy shown in Table 2, the processing temperature is too low and the holding time is insufficient, the residual stress is not eliminated, the grain size is too fine and disordered, and the grain size is finer than 6, which does not meet the requirement. The overall grain size is "too fine and uneven", which is consistent with the defect. Figure 5

[0043] In comparison, when the second predetermined temperature is 1060-1080℃, the second predetermined time is 1-2h, and air cooling is used, the average grain size of the alloy is 3-6, but there are large-size grains with a grain size of 1 in some areas, which does not meet the requirement of the average grain size according to the present application, as shown in Table 2. For the alloy shown in Table 2, the pretreatment temperature is higher than the upper limit of 1040℃ defined in the present application (low temperature upper limit), although the holding time is moderate, but some grains are 3-6, and 1-grade large grains (mixed grains) appear locally, which does not meet the requirement. Figure 9 Figure 9 For the alloy shown in Table 2, the processing temperature is too low and the holding time is insufficient, the residual stress is not eliminated, the grain size is too fine and disordered, and the grain size is finer than 6, which does not meet the requirement. The overall grain size is "too fine and uneven", which is consistent with the defect.

[0044] In comparison, when the second predetermined temperature is 1060-1080℃, the second predetermined time is greater than 2h, and air cooling is used, the average grain size of the alloy is between 1-2, but does not reach 2 (i.e., coarser than 2), which does not meet the requirement of the average grain size according to the present application, as shown in Table 2. For the alloy shown in Table 2, the pretreatment temperature is too high and the holding time is too long, the grains are excessively grown, the grain size is 1-2 (coarser than 2), which does not meet the requirement. The overall grain size is "coarse and uniform", which is consistent with the defect. Figure 10 Figure 10 For the alloy shown in Table 2, the processing temperature is too low and the holding time is insufficient, the residual stress is not eliminated, the grain size is too fine and disordered, and the grain size is finer than 6, which does not meet the requirement. The overall grain size is "too fine and uneven", which is consistent with the defect. Figure 4 Figure 7 For the alloy shown in Table 2, the processing temperature is too low and the holding time is insufficient, the residual stress is not eliminated, the grain size is too fine and disordered, and the grain size is finer than 6, which does not meet the requirement. The overall grain size is "too fine and uneven", which is consistent with the defect.

[0045] In summary, when the low-temperature long-time pretreatment + standard heat treatment method is used, the reasonable heat treatment system is that the second predetermined temperature is 1000-1040℃, and the second predetermined time is 4-10h.

[0046] Similarly, in order to eliminate the residual stress of the alloy and keep the grain size of the alloy at a certain level, after holding at 1100℃, 1120℃, 1140℃, 1160℃, 1180℃, 1200℃ for 5min, 10min, 30min, 1h, 1.5h, 2h, 3h, 4h, respectively, standard heat treatment is performed, and Table 2 shows the grain size of the hot-rolled bar after high-temperature short-time pretreatment + standard heat treatment. ​​​​​

[0047] Table 2 Average grain size of hot-rolled bar after high-temperature short-time pretreatment + standard heat treatment.

[0048]

[0049] As can be seen from Table 2, when the second predetermined temperature is 1120-1160℃, the second predetermined time is 0.5-2h, and air cooling is performed, the average grain size of the alloy is in the range of 2-5, the average grain size of the alloy is in the range of 2-5, and the average grain size meets the requirements of the present application, as shown in Table 1, and the elongation, the reduction of area, and the tensile strength also meet the requirements. Figure 11 As can be seen from Table 2, when the second predetermined temperature is 1120-1160℃, the second predetermined time is 0.5-2h, and air cooling is performed, the average grain size of the alloy is in the range of 2-5, the average grain size of the alloy is in the range of 2-5, and the average grain size meets the requirements of the present application, as shown in Table 1, and the elongation, the reduction of area, and the tensile strength also meet the requirements. Figure 11 As can be seen from Table 2, when the second predetermined temperature is 1120-1160℃, the second predetermined time is 0.5-2h, and air cooling is performed, the average grain size of the alloy is in the range of 2-5, the average grain size of the alloy is in the range of 2-5, and the average grain size meets the requirements of the present application, as shown in Table 1, and the elongation, the reduction of area, and the tensile strength also meet the requirements. Figure 3 As can be seen from Table 2, when the second predetermined temperature is 1120-1160℃, the second predetermined time is 0.5-2h, and air cooling is performed, the average grain size of the alloy is in the range of 2-5, the average grain size of the alloy is in the range of 2-5, and the average grain size meets the requirements of the present application, as shown in Table 1, and the elongation, the reduction of area, and the tensile strength also meet the requirements.

[0050] In contrast, under the same conditions or processes, when the second predetermined temperature is 1120-1160℃, the second predetermined time is greater than 2h, and air cooling is performed, the average grain size of the alloy is 1-2, which does not meet the average grain size requirement of the present application, as shown in Table 1. Figure 12 As can be seen from Table 2, when the second predetermined temperature is 1120-1160℃, the second predetermined time is 0.5-2h, and air cooling is performed, the average grain size of the alloy is in the range of 2-5, the average grain size of the alloy is in the range of 2-5, and the average grain size meets the requirements of the present application, as shown in Table 1, and the elongation, the reduction of area, and the tensile strength also meet the requirements. Figure 12 As can be seen from Table 2, when the second predetermined temperature is 1120-1160℃, the second predetermined time is 0.5-2h, and air cooling is performed, the average grain size of the alloy is in the range of 2-5, the average grain size of the alloy is in the range of 2-5, and the average grain size meets the requirements of the present application, as shown in Table 1, and the elongation, the reduction of area, and the tensile strength also meet the requirements. Figure 11 As can be seen from Table 2, when the second predetermined temperature is 1120-1160℃, the second predetermined time is 0.5-2h, and air cooling is performed, the average grain size of the alloy is in the range of 2-5, the average grain size of the alloy is in the range of 2-5, and the average grain size meets the requirements of the present application, as shown in Table 1, and the elongation, the reduction of area, and the tensile strength also meet the requirements. Figure 11 As can be seen from Table 2, when the second predetermined temperature is 1120-1160℃, the second predetermined time is 0.5-2h, and air cooling is performed, the average grain size of the alloy is in the range of 2-5, the average grain size of the alloy is in the range of 2-5, and the average grain size meets the requirements of the present application, as shown in Table 1, and the elongation, the reduction of area, and the tensile strength also meet the requirements.

[0051] In contrast, under the same conditions or processes, when the second predetermined temperature is 1120-1160℃, the second predetermined time is greater than 2h, and air cooling is performed, the average grain size of the alloy is 1-2, which does not meet the average grain size requirement of the present application, as shown in Table 1. Figure 13 As can be seen from Table 2, when the second predetermined temperature is 1120-1160℃, the second predetermined time is 0.5-2h, and air cooling is performed, the average grain size of the alloy is in the range of 2-5, the average grain size of the alloy is in the range of 2-5, and the average grain size meets the requirements of the present application, as shown in Table 1, and the elongation, the reduction of area, and the tensile strength also meet the requirements. Figure 13 As can be seen from Table 2, when the second predetermined temperature is 1120-1160℃, the second predetermined time is 0.5-2h, and air cooling is performed, the average grain size of the alloy is in the range of 2-5, the average grain size of the alloy is in the range of 2-5, and the average grain size meets the requirements of the present application, as shown in Table 1, and the elongation, the reduction of area, and the tensile strength also meet the requirements. Figure 11 As can be seen from Table 2, when the second predetermined temperature is 1120-1160℃, the second predetermined time is 0.5-2h, and air cooling is performed, the average grain size of the alloy is in the range of 2-5, the average grain size of the alloy is in the range of 2-5, and the average grain size meets the requirements of the present application, as shown in Table 1, and the elongation, the reduction of area, and the tensile strength also meet the requirements. Figure 11 As can be seen from Table 2, when the second predetermined temperature is 1120-1160℃, the second predetermined time is 0.5-2h, and air cooling is performed, the average grain size of the alloy is in the range of 2-5, the average grain size of the alloy is in the range of 2-5, and the average grain size meets the requirements of the present application, as shown in Table 1, and the elongation, the reduction of area, and the tensile strength also meet the requirements.

[0052] In contrast, under the same conditions or processes, when the second predetermined temperature is 1160°C, the second predetermined time is less than 0.5 h, and air cooling is used, the average grain size of the alloy is between 6 and 7, and finer than grade 6, which does not meet the average grain size requirement described in this invention. Figure 14 As shown. For Figure 14 The alloy shown was pretreated at the upper limit of high temperature, but the holding time was insufficient, resulting in most grains being grade 5-6, with some areas containing finer grains (slight mixed grains) than grade 6, which does not meet the requirements. Figure 11 This contrasts with the "fully uniform grains".

[0053] In contrast, under the same conditions or processes, when the second predetermined temperature is 1100℃, the second predetermined time is 0.5h~2h, and air cooling is used, the average grain size of the alloy is grade 3~6. However, some regions contain large grains with a grain size coarser than grade 2, which does not meet the average grain size requirement described in this invention. Figure 15 As shown. For Figure 15 The alloy shown has a pretreatment temperature lower than the 1120℃ (lower limit of high temperature) specified in this invention. Although the holding time is moderate, some grains are grade 3-6, and some areas have large grains (mixed crystals) coarser than grade 2, which does not meet the requirements. Figure 11 This contrasts with the "lack of large grains".

[0054] In contrast, under the same conditions or processes, when the second predetermined temperature is 1100℃, the second predetermined time is greater than 2 hours, and air cooling is used, the average grain size of the alloy is between grade 1 and 2 and coarser than grade 2, which does not meet the average grain size requirement described in this invention. Figure 16 As shown. For Figure 16 The alloy shown has an excessively low temperature and excessive holding time, resulting in excessive grain growth. The grain size is grade 1-2 (coarser than grade 2), which does not meet the requirements. The overall grain size is "coarse," which is consistent with... Figure 12 The defects are consistent.

[0055] In contrast, under the same conditions or processes, when the second predetermined temperature is 1100℃, the second predetermined time is less than 0.5h, and air cooling is used, the average grain size of the alloy is between 8 and 9, finer than grade 6, which does not meet the average grain size requirement described in this invention. Figure 17 As shown. For Figure 17 The alloy shown has an excessively low temperature and insufficient heat preservation, with fine and disordered grains. The grain size is finer than grade 6, failing to meet the requirements. The overall grain size is "too fine and uneven," which is inconsistent with... Figure 13 The defects are consistent.

[0056] In contrast, under the same conditions or processes, when the second predetermined temperature is 1180℃~1200℃, as the second predetermined time (i.e., the holding time) increases, the grain size of the alloy remains between level 1 and 2, and is coarser than level 2, failing to meet the average grain size requirement described in this invention. Figure 18 As shown. For Figure 18 The alloy shown, with a pretreatment temperature exceeding the 1160℃ (high temperature limit) specified in this invention, exhibited severe grain growth regardless of the holding time, with a grain size of only grade 1-2 (coarser than grade 2), completely failing to meet the requirements. All regions showed "abnormally large" grains, with no qualified grains, demonstrating the fatal defect of excessively high temperatures.

[0057] In summary, when using a combination of high-temperature short-time pretreatment and standard heat treatment, a reasonable heat treatment regime is as follows: the second predetermined temperature is 1120℃~1160℃, and the second predetermined time is 0.5h~2h.

[0058] In this invention, whether the low-temperature long-time pretreatment + standard heat treatment method or the high-temperature short-time pretreatment + standard heat treatment method is used, the diameter requirement D ≤ can be obtained. Age-hardening high-temperature alloy hot-rolled bars with a diameter of 40 mm, an average grain size of grade 2 to 6, an elongation of A ≥ 5%, a reduction of area Z ≥ 10%, and a tensile strength Rm ≥ 750 MPa.

[0059] Furthermore, the grain size control method for hot-rolled bars of age-hardening high-temperature alloys described in this invention is not limited to a specific age-hardening high-temperature alloy. All methods that utilize the principles of this invention for grain size control are within the scope of patent protection of this invention.

[0060] The present invention is further illustrated below through specific embodiments: Example 1 The age-hardening high-temperature alloy hot-rolled bar described in this application is obtained using the following methods and steps, and the grain size of the age-hardening high-temperature alloy hot-rolled bar can be controlled to the desired range using the following methods and steps: 1. A vacuum induction melting process combined with vacuum consumable alloy melting was used to obtain an age-hardening superalloy electrode rod. This rod was then subjected to homogenization, forging, and precision forging to obtain the final product. 75mm blank.

[0061] 2. The billet is first held at 1000℃~1200℃ for 1h~4h to reduce the deformation resistance in the alloy, improve the plasticity of the alloy, and promote the dynamic recrystallization of the alloy.

[0062] 3. Use The alloy is rough-rolled on a 550 rolling mill: initial rolling temperature ≥1000℃, final rolling temperature ≥900℃, and 6-8 rolling passes to obtain... 55mm intermediate billet.

[0063] 4. Next, the intermediate billet is finished: the intermediate billet is peeled or polished.

[0064] 5. Reuse The alloy is finished using a 280 rolling mill: initial rolling temperature ≥1000℃, final rolling temperature ≥900℃, and 8-10 rolling passes to obtain... 25mm hot-rolled bar stock.

[0065] 6. Then will 25mm hot-rolled bars were held at 1020℃ for 4 hours and then air-cooled to room temperature.

[0066] 7. Finally, regarding 25mm hot-rolled bars are subjected to standard heat treatment with the following regime: 1100℃~1200℃, holding for 1h~10h, air cooling; 900℃~1100℃, holding for 1h~10h, air cooling; 600℃~1000℃, holding for 1h~24h, air cooling, to obtain age-hardening high-temperature alloy hot-rolled bars, which include the following components by weight percentage: C: 0.05%, Cr: 22%, Al: 0.70%, Ti: 2.2%, Fe: 0.6%, B: 0.01%, Ce: 0.01%, Si: 0.5%, Mn: 0.1%, Cu: 0.05%, with the remainder being Ni and unavoidable impurities.

[0067] 8. The microstructure of 25mm hot-rolled bar after pretreatment and standard heat treatment is as follows: Figure 19 The grains are uniform and consistent, without mixed crystals. Analysis shows a grain size of 3-5, elongation (A) of 9.5%, reduction of area (Z) of 15%, and tensile strength (Rm) of 850 MPa, meeting the usage requirements and clearly demonstrating the practical application effect of this invention. The effects of this embodiment are similar to... Figure 3 (Verification diagram of the scheme) The results are consistent, proving the feasibility of the optimized process.

[0068] Example 2 The age-hardening high-temperature alloy hot-rolled bar described in this application is obtained using the following methods and steps, and the grain size of the age-hardening high-temperature alloy hot-rolled bar can be controlled to the desired range using the following methods and steps: 1. A vacuum induction melting process combined with vacuum consumable alloy melting was used to obtain an age-hardening superalloy electrode rod. This rod was then subjected to homogenization, forging, and precision forging to obtain the final product. 65mm blank.

[0069] 2. The blank is first held at 1000-1200°C for 1-4h to reduce the deformation resistance in the alloy, improve the plasticity of the alloy, and promote dynamic recrystallization of the alloy.

[0070] 3. The alloy is coarsely rolled using a 550 rolling mill: the rough rolling temperature is ≥1000°C. The finish rolling temperature is ≥900°C, and the rolling passes are 6-8 passes to obtain a 50mm intermediate blank.

[0071] 4. The intermediate blank is then finished: the intermediate blank is subjected to peeling or polishing treatment.

[0072] 5. The alloy is then finely rolled using a 280 rolling mill: the rough rolling temperature is ≥1000°C. The finish rolling temperature is ≥900°C, and the rolling passes are 8-10 passes to obtain a 18mm hot-rolled bar.

[0073] 6. The 18mm hot-rolled bar is then held at 1040°C for 6h and air-cooled to room temperature.

[0074] 7. The 18mm hot-rolled bar is finally subjected to standard heat treatment: 1100-1200°C for 1-10h, air-cooled; 900-1100°C for 1-10h, air-cooled; and 600-1000°C for 1-24h, air-cooled, to obtain an age hardening type high-temperature alloy hot-rolled bar comprising the following components by weight percentage: C: 0.03%, Cr: 20%, Al: 0.60%, Ti: 2.0%, Fe: 0.8%, B: 0.005%, Ce: 0.02%, Si: 0.65%, M: 0.2%, Cu: 0.07%, and the balance being Ni and unavoidable impurities.

[0075] 8. The microstructure of the 18mm hot-rolled bar after pretreatment + standard heat treatment is as shown in Figure 20 , the grains are uniform and fine, and there is no mixed crystal. The grain size is 3-4 levels, the elongation A is 16%, the reduction of area Z is 18%, and the tensile strength Rm is 902MPa, meeting the use requirements, further verifying the stability of the low-temperature long-time scheme. The grains of this embodiment are finer than Figure 19 , but are still within the range of 2-6 levels, reflecting the flexibility of the process parameters.

[0076] Example 3 ​​​​The age hardenable superalloy hot-rolled bar described in the present application is obtained by the following method steps, and the grain size of the age hardenable superalloy hot-rolled bar can be controlled to the required range by the following method steps: 1. The electrode bar of the age hardenable superalloy is obtained by using a vacuum induction + vacuum consumable melting process, and then the 85mm blank is obtained by the processing mode of homogenization, breakdown by a forging machine, and finish forging.

[0077] 2. The blank is first heat treated at 1000℃-1200℃ for 1h-4h to reduce the deformation resistance in the alloy, improve the plasticity of the alloy, and promote the dynamic recrystallization of the alloy.

[0078] 3. The alloy is coarsely rolled using a 550 rolling mill: the rolling temperature is ≥1000℃. The final rolling temperature is ≥900℃, and the rolling passes are 6-8 passes, to obtain a 55mm intermediate blank.

[0079] 4. Then the intermediate blank is finished: the intermediate blank is treated by peeling or polishing.

[0080] 5. The alloy is then finished rolled using a 280 rolling mill: the rolling temperature is ≥1000℃. The final rolling temperature is ≥900℃, and the rolling passes are 8-10 passes, to obtain a 30mm hot-rolled bar.

[0081] 6. Then the 30mm hot-rolled bar is heat treated at 1140℃ for 0.5h and air cooled to room temperature.

[0082] 7. Finally, the 30mm hot-rolled bar is subjected to standard heat treatment, and the heat treatment system is: 1100℃-1200℃ for 1h-10h, air cooling; 900℃-1100℃ for 1h-10h, air cooling; 600℃-1000℃ for 1h-24h, air cooling, to obtain the age hardenable superalloy hot-rolled bar, which comprises the following components by weight percentage: C: 0.06%, Cr: 25%, Al: 0.8%, Ti: 2.4%, Fe: 0.7%, B: 0.008%, Ce: 0.015%, Si: 0.6%, Mn: 0.15%, Cu: 0.06%, and the balance is Ni and unavoidable impurities.

[0083] 8. The microstructure of the Figure 21 ​, the grains are uniform and consistent, and there is no mixed crystal. After detection and analysis, the grain size is 3-5 levels, the elongation A is 12%, the section shrinkage rate Z is 16%, the tensile strength Rm is 890MPa, which meets the use requirements, and verifies the actual effect of the high-temperature short-time scheme. The embodiment and Figure 11 The effects are consistent, and it is proved that both schemes (low temperature / high temperature) can achieve the target.

[0084] In summary, the application provides a time-hardening high-temperature alloy hot-rolled bar and a grain size control method thereof. First, a blank required for hot rolling is prepared, and the blank is subjected to heat preservation treatment. Second, the blank is rolled by a 550 / 280 rolling mill to obtain a hot-rolled bar with a desired size. Then, the residual stress in the hot-rolled bar is eliminated by a recrystallization pretreatment method, and the hot-rolled bar is subjected to standard heat treatment to obtain a hot-rolled bar with a desired grain size. The application realizes grain size control of a time-hardening high-temperature alloy hot-rolled bar through the above steps. The use of the above control method can accurately control the grain size of the time-hardening high-temperature alloy, thereby improving the product yield and qualification rate. This has very important guiding significance for domestic enterprises, steel plants and colleges engaged in high-temperature alloy product manufacturing, and will produce significant economic value.

[0085] The application aims to provide a time-hardening high-temperature alloy hot-rolled bar and a grain size control method thereof. When a specific recrystallization annealing pretreatment process is involved, the hot-rolled bar specification, bar grain size level and physical properties need to be set according to the specific recrystallization annealing pretreatment process. The grain size control method of the time-hardening high-temperature alloy hot-rolled bar provided by the application is not limited to the specific time-hardening high-temperature alloy hot-rolled bar described in the application, and any use of the principle of the application to regulate and control the grain size is within the scope of the patent protection of the application.

[0086] The above description is only a preferred embodiment of the application and is not intended to limit the scope of the application; if the application is modified or replaced without departing from the spirit and scope of the application, it should be covered within the protection scope of the claims of the application.

Claims

1. An age hardenable high temperature alloy hot rolled bar, characterized by, The age hardenable high-temperature alloy hot-rolled bar comprises the following components by weight percentage: C: 0.03%~0.06%, Cr: 20%~25%, Al: 0.60%~0.8%, Ti: 2.0%~2.4%, Fe≤0.8%, B≤0.01%, Ce≤0.02%, Si≤0.65%, Mn≤0.2%, Cu≤0.07%, and the rest is Ni and inevitable impurities, the average grain size of the age hardenable high-temperature alloy hot-rolled bar is 2~6 levels, the diameter is ≤ 40mm, the elongation A≥5%, the area reduction Z≥10% and the tensile strength R m ≥750MPa.

2. A method of controlling the grain size of a hot-rolled bar of an age hardenable high-temperature alloy according to the preceding claim 1, characterized in that The method comprises the following steps: S10. Obtain a blank required for a hot-rolled bar of an age hardening type high-temperature alloy, keep the blank at a first predetermined temperature for a first predetermined time, then perform rough rolling on the blank to obtain an intermediate blank, perform finishing on the intermediate blank, and then perform finish rolling to obtain a hot-rolled bar of a specific size; S20. Perform recrystallization annealing pretreatment on the hot-rolled bar of the specific size at a second predetermined temperature for a second predetermined time, and then air cool to room temperature, wherein the second predetermined temperature and the second predetermined time meet the requirements of low temperature and long time or high temperature and short time; and S30. Perform standard heat treatment on the hot-rolled bar after air cooling to obtain the hot-rolled bar of the age hardening type high-temperature alloy.

3. The grain size control method of the precipitation hardening superalloy hot-rolled bar according to claim 2, characterized by, In step S20, under the requirement of low temperature and long time, the second predetermined temperature is 1000-1040℃, and the second predetermined time is 4-10h.

4. The grain size control method of the precipitation hardening superalloy hot-rolled bar according to claim 2, characterized by, In step S20, under the requirement of high temperature and short time, the second predetermined temperature is 1120-1160℃, and the second predetermined time is 0.5-2h.

5. The grain size control method of the precipitation hardening superalloy hot-rolled bar according to claim 2, characterized by, In step S10, an electrode rod of age hardenable superalloy is obtained by a vacuum induction and vacuum consumable melting process, and then the electrode rod is subjected to homogenization treatment, blooming by a forging machine, and finish forging to obtain a blank required for the age hardenable superalloy hot-rolled rod material, and the diameter of the blank is 60mm 90mm.

6. The grain size control method of the precipitation hardening superalloy hot-rolled bar according to claim 2, characterized by In step S10, the first predetermined temperature is 1000-1200℃, and the first predetermined time is 1-4h.

7. The grain size control method of the precipitation hardening superalloy hot-rolled bar according to claim 5, characterized by, In step S10, the following is used 550 A rough rolling is performed on the billet by a rolling mill, wherein the rough rolling has a rough rolling start temperature ≥ 1000 °C, the rough rolling has a rough rolling finish temperature ≥ 900 °C, the rough rolling has a rolling pass number of 6-8 passes, and the rough rolling obtains a 50mm 60mm intermediate billet.

8. The grain size control method of the precipitation hardening superalloy hot-rolled bar according to claim 2, characterized by, In step S10, the finishing comprises skinning or polishing treatment on the intermediate blank.

9. The grain size control method of the precipitation hardening superalloy hot-rolled bar according to claim 7, characterized by, In step S10, the following is used 280The finished intermediate billet is finish-rolled using a rolling mill, wherein the finish-rolling has a starting temperature ≥ 1000°C, the finish-rolling has a final temperature ≥ 900°C, the finish-rolling has 8-10 rolling passes, and a hot-rolled bar ≤ 40 mm is obtained.

10. The method of controlling the grain size of an age hardenable superalloy hot-rolled bar according to claim 2, characterized in that, In step S30, the heat treatment system of the standard heat treatment is as follows: 1100-1200℃ for 1-10h, air cooling; 900-1100℃ for 1-10h, air cooling; and 600-1000℃ for 1-24h, air cooling. ​

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