10Cr9Mo1VNbN forge piece and subcritical annealing method for grain refinement of 10Cr9Mo1VNbN forge piece
Through subcritical annealing and performance heat treatment, the problem of coarse grains of 10Cr9Mo1VNbN steel forgings was solved, and grain refinement was achieved, improving the mechanical and corrosion resistance of the forgings.
Patent Information
- Application Number
- CN202411292436.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-14
- Publication Date
- 2025-01-03
AI Technical Summary
During the forging process, the grains of 10Cr9Mo1VNbN steel forgings grow rapidly due to long-term insulation, which affects its mechanical properties and corrosion resistance. It is difficult for traditional preparatory heat treatment to effectively refine the grains.
Preparation heat treatment was carried out by subcritical annealing method. By heating and insulation at 780-830°C, cooling speed was controlled, grain growth was suppressed, and new fine grains were formed by combining quenching and tempering.
Effectively refine the grains of 10Cr9Mo1VNbN forgings to improve their yield strength, tensile strength and corrosion resistance, ensure that the grain size is above 7 levels, and significantly improve elongation and cross-section shrinkage.
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Figure CN119242893A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of heat treatment of metal materials, in particular to a 10Cr9Mo1VNbN forging and a subcritical annealing method for grain refinement thereof. Background Art
[0002] 10Cr9Mo1VNbN steel is a high temperature alloy steel, the main components are chromium, molybdenum, vanadium and other elements, with excellent high temperature strength, good welding performance and corrosion resistance. Due to its excellent performance, 10Cr9Mo1VNbN steel has been widely used in the petroleum, chemical, electric power and other industries, especially in the manufacture of high temperature and high pressure equipment has important application value.
[0003] However, in order to ensure the deformation of the forgings during the forging process, the initial forging temperature of 10Cr9Mo1VNbN steel is basically controlled at 1150℃. If the temperature is kept for too long, the grains of the forgings will grow rapidly. The large deformation rate causes the internal structure of the forgings to be broken but there is no time for recrystallization to occur, and the grains remain coarse when they are broken. Coarse grains will seriously affect the mechanical properties and corrosion resistance of 10Cr9Mo1VNbN steel, making the welding performance of the forgings worse, increasing the microscopic defects of the forgings, and reducing their service life and safety. Traditional preparatory heat treatment methods include full annealing or multiple positive tempering. Full annealing involves heating the forgings to a temperature between 1050-1150℃ and maintaining it for a certain period of time, followed by cooling by furnace cooling or rate-limited cooling. Due to the high heating temperature, this method places high demands on the heating equipment, especially the heat treatment furnace. At the same time, in order to prevent excessive growth of grains at high temperatures, the heating temperature needs to be strictly controlled, and it is not easy to achieve the effect of grain refinement.
[0004] Therefore, how to refine the grains of 10Cr9Mo1VNbN forgings and improve their performance has become an urgent problem to be solved. Summary of the invention
[0005] In view of the above analysis, the present invention aims to provide a 10Cr9Mo1VNbN forging and a subcritical annealing method for grain refinement thereof, so as to solve the problem of coarse grains and poor performance of the existing 10Cr9Mo1VNbN forging.
[0006] On the one hand, the present invention provides a subcritical annealing method for grain refinement of 10Cr9Mo1VNbN forgings, wherein a forging blank is obtained after smelting and forging, and the obtained forging blank is subjected to preliminary heat treatment and performance heat treatment to obtain a 10Cr9Mo1VNbN forging;
[0007] wherein the preliminary heat treatment is subcritical annealing;
[0008] The subcritical annealing is firstly heated to 780-830°C at a heating rate of ≤80°C / h, and kept at this temperature for more than 2h, and then cooled to a limited temperature and taken out of the furnace.
[0009] Furthermore, when the effective heat treatment cross-sectional size of the forging is t≤100 mm, the subcritical annealing is first heated to 780-830° C. at a heating rate of 70-80° C. / h, and kept at this temperature for more than 2 hours, and then air-cooled.
[0010] Furthermore, when the effective heat treatment cross-sectional size t of the forging is 100-500 mm, the subcritical annealing is first heated to 780-830°C at a heating rate of ≤70°C / h, and kept warm for 4-10h, and then cooled to 350-200°C at a cooling rate of ≤50°C / s before being taken out of the furnace.
[0011] Furthermore, the performance heat treatment includes quenching and tempering treatment,
[0012] The quenching temperature is 1000-1060°C, and the holding time is ≥2h / 100mmm, but not less than 2h;
[0013] The tempering temperature is 680-770°C, and the holding time is ≥2.5h / 100mm, but not less than 3h.
[0014] Furthermore, the chemical composition of the 10Cr9Mo1VNbN forging includes, by mass percentage: C: 0.08-0.12%, Mn: 0.03-0.60%, Ni≤0.40%, Cr: 8.0-9.5%, Mo: 0.85-1.05%, and Nb: 0.06-0.10%.
[0015] Furthermore, the smelting process adopts vacuum electroslag remelting, double vacuum smelting or vacuum arc furnace smelting, the hydrogen content is below 2ppm, and the nitrogen content is 0.03-0.07%.
[0016] Furthermore, the heating temperature of the forging is 1150-850°C, and the deformation rate is 0.001-5.0s -1 .
[0017] Furthermore, the grain size of the 10Cr9Mo1VNbN forging is 7-7.5.
[0018] Furthermore, the yield strength of the 10Cr9Mo1VNbN forging is above 515 MPa, the tensile strength is above 660 MPa, the cross-sectional shrinkage is above 70%, and the elongation is above 27.5%.
[0019] On the other hand, the present invention provides a 10Cr9Mo1VNbN forging, which is prepared by the method described in the present invention.
[0020] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:
[0021] 1. The present invention uses preliminary heat treatment and performance heat treatment to treat 10Cr9Mo1VNbN forgings, wherein the preliminary heat treatment uses subcritical annealing. During the heating process, recrystallization occurs to form new and finer grains. After heating to a certain temperature, the temperature is kept, so that the dislocations and grain boundaries inside the forgings are relaxed and rearranged. As the temperature rises, the grains do not austenitize during the subcritical annealing process because the temperature is lower than the phase transition point, and no new crystal nuclei are generated, thereby inhibiting the growth of the grains, thereby refining the grains, so that the grain size of the 10Cr9Mo1VNbN forgings is maintained above level 7.
[0022] 2. During subcritical annealing, grain boundaries can migrate at lower temperatures, causing recrystallization of grains. Grain boundary migration is affected by temperature and holding time. Appropriate temperature and time can promote grain boundary migration. In addition, by controlling the heating and cooling rates, the nucleation and growth conditions of the grains are optimized, thereby achieving grain refinement.
[0023] 3. The performance heat treatment includes quenching and tempering, wherein the quenching temperature is 1000-1060℃, the holding time is ≥2h / 100mm, but not less than 2h; wherein the tempering temperature is 680-770℃, the holding time is ≥2.5h / 100mm, but not less than 3h. After the preliminary heat treatment and performance heat treatment, the yield strength of the 10Cr9Mo1VNbN forging is above 515MPa, the tensile strength is above 660MPa, the cross-sectional shrinkage is above 70%, and the elongation is above 27.5%.
[0024] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.
[0026] Figure 1 This is a photo of the fully annealed comparative example 1;
[0027] Figure 2 This is a photo of multiple normalizing of Comparative Example 2;
[0028] Figure 3 This is the metallographic photograph of Example 1. DETAILED DESCRIPTION
[0029] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.
[0030] 10Cr9Mo1VNbN steel is a high-temperature alloy steel. Due to its excellent performance, it is widely used. 10Cr9Mo1VNbN steel is often used to make forgings. During the forging process, in order to ensure the deformation of the forgings, the initial forging temperature of the forgings is basically controlled above 1150℃. Long-term heat preservation at too high a temperature will cause the grains of the forgings to grow rapidly; the large deformation rate causes the internal structure of the forgings to be broken but there is no time for recrystallization to occur, and the grains remain in a coarse state when they are broken. Coarse grains will seriously affect the mechanical properties and corrosion resistance of 10Cr9Mo1VNbN steel, making the welding performance of the forgings worse, increasing the microscopic defects of the forgings, and reducing their service life and safety.
[0031] In order to refine the grains, subsequent heat treatment must be performed. The existing preliminary heat treatment uses full annealing or multiple positive tempering, but its grain refinement and performance improvement are limited. After treatment, the grains are refined to below level 6.5. In addition, the existing heat treatment needs to be carried out at a higher temperature of 1050-1150℃, which also leads to high energy consumption.
[0032] Therefore, the present invention provides a subcritical annealing method for grain refinement of 10Cr9Mo1VNbN forgings, wherein a forging blank is obtained after smelting and forging, and the obtained forging blank is subjected to preliminary heat treatment and performance heat treatment to obtain a 10Cr9Mo1VNbN forging;
[0033] wherein the preliminary heat treatment is subcritical annealing;
[0034] The subcritical annealing is firstly heated to 780-830°C at a heating rate of ≤80°C / h, and kept at this temperature for more than 2h, and then cooled to a limited temperature and taken out of the furnace.
[0035] Compared with the prior art, the present invention uses subcritical annealing and performance heat treatment to treat 10Cr9Mo1VNbN forgings. During the heating process, recrystallization occurs, and the crystal nuclei formed at the grain boundaries or distortion zones form new, finer grains. After heating to a certain temperature, the temperature is kept, so that the dislocations and grain boundaries inside the forgings are relaxed and rearranged. As the temperature rises, the grains do not austenitize during the subcritical annealing process because the temperature is lower than the phase transition point, and no new crystal nuclei are generated, thereby inhibiting the growth of the grains, thereby refining the grains, so that the grain size of the 10Cr9Mo1VNbN forgings is maintained above level 7.
[0036] After preliminary heat treatment and performance heat treatment, the yield strength of 10Cr9Mo1VNbN forgings is above 515MPa, the tensile strength is above 660MPa, the cross-sectional shrinkage is above 70%, and the elongation is above 27.5%.
[0037] Specifically, the smelting process adopts vacuum electroslag remelting, double vacuum smelting or vacuum arc furnace smelting, the hydrogen content is below 2ppm, and the nitrogen content is 0.03-0.07%.
[0038] It should be noted that the smelting process of 10Cr9Mo1VNbN steel ingot adopts advanced vacuum electroslag remelting technology, double vacuum smelting method or vacuum arc furnace smelting method, etc. The key to this step is the strict control of gas content. Through this technology, it can ensure that the hydrogen content is strictly limited to below 2ppm, and the nitrogen content is controlled within the upper limit range of 0.03-0.07%. Such a level of control significantly reduces the content of gas inclusions, thereby improving the purity and overall performance of the forgings.
[0039] Specifically, the heating temperature of the forging is 1150-850°C, and the deformation rate is 0.001-5.0s -1 .
[0040] It should be noted that the forging temperature of 10Cr9Mo1VNbN forgings is 1150-850℃, and they are immediately put into the furnace for heating after forging. The purpose of this step is to prevent the forgings from generating excessive stress during the forging process, and to immediately put them into the furnace for heating to avoid cracks in the forgings caused by the air cooling time after forging. High temperature furnace entry helps to relieve internal stress and ensure the shape and dimensional accuracy of the forgings.
[0041] It should be noted that during the forging process, the initial forging temperature is basically controlled above 1150°C, while the final forging temperature is controlled above 850°C to ensure that no serious crack defects are generated during the forging process.
[0042] Specifically, the subcritical annealing is first heated to 780-830° C. at a heating rate of ≤80° C. / h, and kept at this temperature for more than 2 hours, and then cooled to a limited temperature before being taken out of the furnace.
[0043] It should be noted that preliminary heat treatment is a key step in the entire manufacturing process. Its core goal is to deeply optimize the microstructure of the forging and thus comprehensively improve its overall performance. This process begins after forging is completed, and the forging is heated to 10-60°C below the Ac1 temperature at a relatively fast rate. After the forging surface reaches this target temperature, it is kept warm for a period of time to ensure that the temperature can be evenly distributed throughout the forging. The length of the holding time depends on the effective heat treatment thickness of the forging to ensure the consistency and uniformity of the heat treatment effect.
[0044] Subsequently, the forging is cooled to a certain temperature by limited speed cooling and then air-cooled or directly air-cooled to room temperature. This cooling process requires strict control of the cooling rate to prevent excessive cooling rate from generating new internal stress. Accurately controlling the cooling rate is the key to ensuring the performance of the forging.
[0045] The advantages of this subcritical annealing preparatory heat treatment method are as follows: during the subcritical annealing process, the forgings will recrystallize at the beginning of heating to form new and finer grains, and after heating to a certain temperature, they will be kept warm, so that the dislocations and grain boundaries inside the forgings can be relaxed and rearranged. As the temperature rises, the grains will not austenitize during the subcritical annealing process because the temperature is lower than the phase transition point, so no new crystal nuclei will be generated, thereby inhibiting the growth of the grains, which helps to maintain a fine grain structure.
[0046] During subcritical annealing, grain boundaries can migrate at lower temperatures, causing recrystallization of grains. Grain boundary migration is affected by temperature and holding time. Appropriate temperature and time can promote grain boundary migration, thereby refining grains. At the same time, during subcritical annealing, carbides and alloying elements will precipitate at grain boundaries and within grains. These precipitates can act as obstacles to grain growth, thereby inhibiting grain growth and refining grains.
[0047] During the heating process, dislocations will move and reorganize, which helps to refine the grains. The movement and reorganization of dislocations can break the original grain structure, re-nucleate, and form new grains.
[0048] During the subcritical annealing process, the nucleation and growth conditions of the grains are optimized by controlling the heating and cooling rates, thereby achieving grain refinement. Through this series of preliminary heat treatment steps, we can effectively optimize the microstructure of the 10Cr9Mo1VNbN forgings, laying a solid foundation for subsequent performance heat treatment.
[0049] Preferably, when the effective heat treatment cross-sectional size of the forging is t≤100 mm, the subcritical annealing is first heated to 780-830° C. at a heating rate of 70-80° C. / h, and kept at this temperature for more than 2 hours, and then air-cooled.
[0050] Preferably, when the effective heat treatment cross-sectional size t of the forging is 100-500 mm (excluding the point value of 100 mm), the subcritical annealing is first heated to 780-830°C at a heating rate of ≤70°C / h, and kept warm for 4-10h, and then cooled to 350-200°C at a cooling rate of ≤50°C / s before taking out of the furnace.
[0051] More preferably, when the effective heat treatment cross-sectional size of the forging is 100<t≤200mm, the subcritical annealing is first heated to 780-830℃ at a heating rate of ≤70℃ / h and kept warm for more than 4h, and then cooled to 350℃ at a cooling rate of ≤50℃ / h and air-cooled out of the furnace.
[0052] More preferably, when the effective heat treatment cross-sectional size of the forging is 200<t≤300mm, the subcritical annealing is first heated to 780-830℃ at a heating rate of ≤60℃ / h and kept warm for more than 6h, and then cooled to 300℃ at a cooling rate of ≤40℃ / h and air-cooled out of the furnace.
[0053] More preferably, when the effective heat treatment cross-sectional size of the forging is 300<t≤500mm, the subcritical annealing is first heated to 780-830℃ at a heating rate of ≤50℃ / h, and kept warm for more than 8h-10h, and then cooled to 200℃ at a cooling rate of ≤30℃ / h and air-cooled out of the furnace.
[0054] It should be noted that, in the present invention, the subcritical annealing can change the heating rate, holding time, cooling rate and temperature before leaving the furnace according to the effective heat treatment cross-sectional size of the forging. In addition, the subcritical annealing provided by the present invention can repeatedly treat the forging until the grain size of the forging is above level 7.
[0055] Specifically, the performance heat treatment includes quenching and tempering treatment.
[0056] The quenching temperature is 1000-1060°C, and the holding time is ≥2h / 100mmm, but not less than 2h;
[0057] The tempering temperature is 680-770°C, and the holding time is ≥2.5h / 100mm, but not less than 3h.
[0058] It should be noted that on the basis of subcritical annealing of forgings, a performance heat treatment process is further combined. Such a heat treatment process can ensure that 10Cr9Mo1VNbN forgings have fine grains while also having good mechanical properties and heat resistance.
[0059] Specifically, the chemical composition of the 10Cr9Mo1VNbN forging includes, by mass percentage, C: 0.08-0.12%, Mn: 0.03-0.60%, Ni≤0.40%, Cr: 8.0-9.5%, Mo: 0.85-1.05%, Nb: 0.06-0.10%, and the balance is Fe.
[0060] It should be noted that in the present invention, 10Cr9Mo1VNbN steel is used to prepare forgings, which mainly include elements such as C, Mn, Ni, Cr, Mo, and Nb, and the hydrogen content is controlled to be below 2ppm, and the nitrogen content is 0.03-0.07%. Within the above range, the elements cooperate with each other, and after forging, subcritical annealing and performance heat treatment, the resulting forgings have higher performance and finer grains. The yield strength of the 10Cr9Mo1VNbN forging is above 515MPa, the tensile strength is above 660MPa, the cross-sectional shrinkage is above 70%, the elongation is above 27.5%, and the grain size is maintained above 7 levels.
[0061] In order to more clearly describe the present invention, it is further illustrated by the following examples and comparative examples.
[0062] Example 1
[0063] After smelting and forging, a forging blank is obtained, and then the forging blank is subjected to preliminary heat treatment and performance heat treatment to obtain a 10Cr9Mo1VNbN forging.
[0064] The steel ingot is smelted in a vacuum arc furnace, and its chemical composition is C: 0.09%, Mn: 0.035%, Ni: 0.25%, Cr: 8.0%, Mo: 1.05%, Nb: 0.07%, H: 2ppm, N: 0.04%.
[0065] The forging process is one upsetting and one drawing process, and the blank is forged into 630×130×45mm. The starting forging temperature is 1150℃, the final forging temperature is 850℃, the forging is formed in one fire, and the deformation rate is 5s -1 ; Decomposed into 20×20×20mm forging specimens, the effective heat treatment section size t of the specimen is 20mm.
[0066] The preliminary heat treatment is subcritical annealing;
[0067] The subcritical annealing is first heated to 780°C at a heating rate of 80°C / h, and kept at this temperature for 2h, and then air-cooled out of the furnace;
[0068] The performance heat treatment includes quenching and tempering treatment. The quenching temperature is 1040° C.×2h, and the quenching adopts air cooling. The tempering temperature is 770° C.×2h, and the cooling method is air cooling.
[0069] Example 2
[0070] The preparation process of Example 2 is substantially the same as that of Example 1, except that in Example 2, a pancake-shaped forging blank of Φ1400×330 mm is finally forged, the final forging temperature is 850°C, and the effective heat treatment section size t is 330 mm.
[0071] After forging, the forging is first heated to 790°C at a heating rate of 50°C / h, and then kept warm for 8 hours; then cooled to 200°C at a cooling rate of ≤30°C / h, and the forging is air-cooled to room temperature after being taken out of the furnace.
[0072] Forging performance heat treatment quenching temperature is 1040℃×6h, quenching adopts water cooling to improve the impact toughness of forgings, tempering temperature is 740℃×9h, cooling method is air cooling.
[0073] Example 3
[0074] The preparation process of Example 3 is substantially the same as that of Example 1, except that in Example 3, the final forged hollow axial forging with an outer shape of 2100×1310×1310mm and an inner hole of Φ850mm is obtained, the starting forging temperature is 1150°C, the final forging temperature is 850°C, and the effective heat treatment section size t is 230mm.
[0075] After forging, the forging is first heated to 810℃ at a rate of 60℃ / h, and then kept at temperature for 6h to ensure that the internal temperature and structure of the material are fully homogenized. Then it is cooled to 300℃ at a cooling rate of ≤40℃ / h, and the forging is air-cooled to room temperature after being taken out of the furnace.
[0076] Forging performance heat treatment quenching temperature is 1040℃×5h, quenching adopts oil cooling method, tempering temperature is 770℃×6h, cooling method is air cooling.
[0077] Example 4
[0078] The preparation process of Example 4 is substantially the same as that of Example 1, except that in Example 4, the final forging is a forging with an outer shape of Φ130×1200mm, the starting forging temperature is 1150°C, the final forging temperature is 850°C, and the effective heat treatment section size t is 130mm.
[0079] After forging, the forging is first heated to 800℃ at a heating rate of 70℃ / h, and then kept warm for 4h to ensure that the internal temperature and structure of the material are fully uniform. Then it is cooled down to 350℃ at a cooling rate of ≤50℃ / h, and the forging is air-cooled to room temperature after being taken out of the furnace.
[0080] Forging performance heat treatment quenching temperature is 1040℃×3h, quenching adopts oil cooling method, tempering temperature is 740℃×4h, cooling method is air cooling.
[0081] Comparative Example 1
[0082] The preparation process of Comparative Example 1 is substantially the same as that of Example 1, except that the annealing process in Comparative Example 1 is as follows: first, the temperature is kept at 600-650°C for 2 hours, then the temperature is increased to 1050°C at a heating rate of 80°C / h, the forging is kept at temperature for 6 hours after reaching the temperature, and then cooled to below 200°C at ≤40°C / h before being removed from the furnace.
[0083] Comparative Example 2
[0084] The preparation process of Comparative Example 2 is substantially the same as that of Example 1, except that the normalizing process (including two normalizing and tempering) in Comparative Example 2 is:
[0085] First positive tempering: keep at 600-650℃ for 2h, increase the temperature to 930℃ at a heating rate of 80℃ / h, keep for 2h, air cool to room temperature, then heat to 680℃ and keep for 3h, air cool to room temperature;
[0086] Second positive tempering: keep at 600-650℃ for 2h, increase the temperature to 1040℃ at a heating rate of 80℃ / h, keep for 2h, air cool to room temperature, then heat to 680℃ and keep for 3h, air cool to room temperature.
[0087] Performance Testing
[0088] The above-mentioned Examples 1-4 and Comparative Examples 1-2 were subjected to performance tests and grain size tests. After heat treatment, the decarburized layer of the samples was removed by machining, and the grain size of the samples was tested. The test results are shown in Tables 1 and 2.
[0089] Table 1 Grain detection results after heat treatment
[0090] Group Average grain diameter Grain grade Example 1 25-32μm Level 7-7.5 Example 2 22-32μm Level 7-7.5 Example 3 30μm Level 7 Example 4 23-28μm Level 7-7.5 Comparative Example 1 60-75μm Level 4.5-5 Comparative Example 2 35-40μm Level 6-6.5
[0091] Table 2 Performance test results of forgings after heat treatment
[0092]
[0093]
[0094] Combined with Examples 1-4 and Comparative Examples 1-2 and with reference to Tables 1 and 2 and Figure 1-3 It can be seen that the forgings obtained by forging, subcritical annealing and performance heat treatment according to the scheme adopted in Examples 1-4 of the present invention have higher performance and finer grains. The yield strength of the 10Cr9Mo1VNbN forging is above 515MPa, the tensile strength is above 660MPa, the cross-sectional shrinkage is above 70%, the elongation is above 27.5%, and the grain size is maintained above 7 levels.
[0095] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.
Claims
1. A subcritical annealing method for grain refinement of 10Cr9Mo1VNbN forgings, characterized in that: After smelting and forging, a forging blank is obtained, and then the forging blank is subjected to preliminary heat treatment and performance heat treatment to obtain a 10Cr9Mo1VNbN forging. wherein the preliminary heat treatment is subcritical annealing; The subcritical annealing is firstly heated to 780-830°C at a heating rate of ≤80°C / h, and kept at this temperature for more than 2h, and then cooled to a limited temperature and taken out of the furnace.
2. The subcritical annealing method for grain refinement of 10Cr9Mo1VNbN forgings according to claim 1, characterized in that: When the effective heat treatment cross-sectional size of the forging is t≤100mm, the subcritical annealing is first heated to 780-830°C at a heating rate of 70-80°C / h, and kept at this temperature for more than 2h, and then air-cooled.
3. The subcritical annealing method for grain refinement of 10Cr9Mo1VNbN forgings according to claim 1, characterized in that: When the effective heat treatment cross-sectional size t of the forging is 100-500mm, the subcritical annealing is first heated to 780-830°C at a heating rate of ≤70°C / h, and kept warm for 4-10h, and then cooled to 350-200°C at a cooling rate of ≤50°C / s before being taken out of the furnace.
4. The subcritical annealing method for grain refinement of 10Cr9Mo1VNbN forgings according to claim 1, characterized in that: The performance heat treatment includes quenching and tempering treatment, The quenching temperature is 1000-1060°C, and the holding time is ≥2h / 100mmm, but not less than 2h; The tempering temperature is 680-770°C, and the holding time is ≥2.5h / 100mm, but not less than 3h.
5. The subcritical annealing method for grain refinement of 10Cr9Mo1VNbN forgings according to claim 1, characterized in that: The chemical composition of the 10Cr9Mo1VNbN forging includes, by mass percentage, C: 0.08-0.12%, Mn: 0.03-0.60%, Ni≤0.40%, Cr: 8.0-9.5%, Mo: 0.85-1.05%, and Nb: 0.06-0.10%.
6. The subcritical annealing method for grain refinement of 10Cr9Mo1VNbN forgings according to claim 1, characterized in that: The heating temperature of the forging is 1150-850°C, and the deformation rate is 0.001-5.0s -1 .
7. The subcritical annealing method for grain refinement of 10Cr9Mo1VNbN forgings according to claim 1, characterized in that: The smelting process adopts vacuum electroslag remelting, double vacuum smelting or vacuum arc furnace smelting, the hydrogen content is below 2ppm, and the nitrogen content is 0.03-0.07%.
8. The subcritical annealing method for grain refinement of 10Cr9Mo1VNbN forgings according to claim 1, characterized in that: The grain size of the 10Cr9Mo1VNbN forging is 7-7.
5.
9. The subcritical annealing method for grain refinement of 10Cr9Mo1VNbN forgings according to claim 1, characterized in that: The 10Cr9Mo1VNbN forging has a yield strength of more than 515MPa, a tensile strength of more than 660MPa, a cross-sectional shrinkage of more than 70%, and an elongation of more than 27.5%.
10. A 10Cr9Mo1VNbN forging, characterized in that: It is prepared by the method according to any one of claims 1 to 9.