Production method for F91 forged three-way forge piece of ultra-supercritical unit

Abstract

The invention discloses a production method of an ultra-supercritical unit F91 forged three-way forge piece, which sequentially comprises the steps of heating before forging, forging, annealing, rough turning, normalizing and tempering, the forge piece is made of martensite heat-resistant alloy steel with the model of ASTMA182F91, and the forge piece comprises the following components in percentage by mass: 20-30% of martensite heat-resistant alloy steel with the model of ASTMA182F91; the martensite heat-resistant alloy steel is prepared from 0.08%-0.12% of C, 0.2%-0.5% of Si, 0.3%-0.6% of Mn, smaller than or equal to 0.015% of P, smaller than or equal to 0.005% of S, smaller than or equal to 0.4% of Ni, 8%-9.5% of Cr, 0.06%-0.08% of Nb, smaller than or equal to 0.3% of Cu, 0.85%-1.05% of Mo, smaller than or equal to 0.02% of Al, smaller than or equal to 0.01% of Ti, 0.055%-0.068% of N, 0.18%-0.22% of V, smaller than or equal to 0.01% of Zr and the balance Fe and inevitable impurities. And the mass of the raw material piece heated before forging is 15-30 t. By setting the content of the N element to be higher and limiting the mass ratio of the N element to the Al element, the mechanical property of the forged piece at the high temperature is improved. The forging is air-cooled to a proper temperature and then is tempered, so that the production time is shortened under the condition that the high-temperature performance of the forging is basically unchanged.

Description

Technical Field

[0001] This invention relates to the field of tee forging technology, specifically to a production method for forged tee parts for ultra-supercritical unit F91. Background Technology

[0002] Currently, wind power and photovoltaic power generation are developing rapidly with policy support, while thermal power generation remains the main mode of power generation. Large-capacity thermal power units require the use of T-shaped forgings that have good mechanical properties at high temperatures.

[0003] ASTM A182F91 martensitic heat-resistant alloy steel is a type of martensitic heat-resistant steel widely used in high-temperature and high-pressure environments. Its excellent mechanical properties and corrosion resistance make it a key material in industries such as power, petrochemicals, and nuclear energy.

[0004] Chinese invention patent CN 114959456 A discloses a nuclear power SA182F91 valve body and its manufacturing method. The SA182F91 valve body manufactured by this invention can be applied to a 600MW demonstration fast reactor project and meets the requirements of the "Technical Conditions for All Forged Valves of the Main Steam System of the 600MW Demonstration Fast Reactor Project". Currently, some manufacturers have proposed higher high-temperature mechanical performance requirements for tee forgings, and the solution provided by Chinese invention patent CN 114959456 A cannot meet these requirements. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects in the existing technology and provide a production method for forged tee forgings of ultra-supercritical unit F91, which produces tee forgings with good high-temperature mechanical properties.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: a production method for F91 forged tee for ultra-supercritical units, comprising sequential steps of pre-forging heating, forging, annealing, rough turning, normalizing, and tempering. The forging is made of martensitic heat-resistant alloy steel of type ASTM A182F91, and the composition of the martensitic heat-resistant alloy steel by mass percentage is: C: 0.08%~0.12%, Si: 0.2%~0.5%, Mn: 0.3%~0.6%, P≤0.015%, S≤0.005%, Ni≤0.4%, Cr: 8%~9.5%, Nb: 0.06%~0.08%, Cu≤0.3%, Mo: 0.85%~1.05%, Al≤0.02%, Ti≤0.01%, N: 0.055%~0.068%, V: 0.18%~0.22%, Zr≤0.01%, with the balance being Fe and unavoidable impurities; The mass of the raw material heated before forging is 15~30t.

[0007] Furthermore, the nitrogen content in the martensitic heat-resistant alloy steel can be selected as a point value of 0.055%, 0.058%, 0.061%, 0.064%, 0.066%, or 0.068%, or a range of two of the above point values ​​as the maximum and minimum values; the mass of the raw material heated before forging can be selected as a point value of 15, 20, 25, or 30 t, or a range of two of the above point values ​​as the maximum and minimum values.

[0008] A preferred technical solution is that the mass ratio of N to Al in the composition of the martensitic heat-resistant alloy steel is greater than 5.

[0009] A preferred technical solution is that the pre-forging heating step includes: S00: The forging is heated to 280~310℃ at a heating rate of no more than 50℃ / h and held for 3.5~4.5h; S01: The forging is heated to 580~610℃ at a heating rate of no more than 50℃ / h and held for 3.5~4.5h; S02: The forging is heated to 980~1010℃ at a heating rate of no more than 80℃ / h and held for 3.5~4.5h; S03: The forging is heated to 1170~1200℃ at a heating rate of no more than 80℃ / h and held for 5.5~6.5h.

[0010] Further, S00: The forging is heated at a heating rate not exceeding 50℃ / h to points of 280, 290, 300, and 310℃, or a range of two of the above points as the maximum and minimum values, and held at that temperature for 3.5, 4, and 4.5 hours, or a range of two of the above points as the maximum and minimum values; S01: The forging is heated at a heating rate not exceeding 50℃ / h to points of 580, 590, 600, and 610℃, or a range of two of the above points as the maximum and minimum values, and held at that temperature for 3.5, 4, and 4.5 hours, or a range of two of the above points as the maximum and minimum values; S02: The forging is heated at a rate not exceeding 80℃ / h to point values ​​of 980, 990, 1000, and 1010℃, or a range of two of the above points as the maximum and minimum values, and held at these temperatures for 3.5, 4, and 4.5 hours, or a range of two of the above points as the maximum and minimum values; S03: The forging is heated at a rate not exceeding 80℃ / h to point values ​​of 1170, 1180, 1190, and 1200℃, or a range of two of the above points as the maximum and minimum values, and held at these temperatures for 5.5, 6, and 6.5 hours, or a range of two of the above points as the maximum and minimum values.

[0011] The preferred technical solution is that the total forging ratio of the forging is 6 or higher.

[0012] The preferred technical solution is that the forging step includes two alternating upsetting and two drawing operations, wherein the forging ratio of the first upsetting is 1.67~1.87, the forging ratio of the first drawing is 1.28~1.48, the forging ratio of the second upsetting is 1.7~1.9, and the forging ratio of the second drawing is 1.41~1.61.

[0013] Furthermore, the first upsetting forging ratio can be selected as a point value of 1.67, 1.7, 1.73, 1.77, 1.83, or 1.87, or a range of two of the above point values ​​as the maximum and minimum values; the first drawing forging ratio can be a point value of 1.28, 1.38, or 1.48, or a range of two of the above point values ​​as the maximum and minimum values; the second upsetting forging ratio can be a point value of 1.7, 1.8, or 1.9, or a range of two of the above point values ​​as the maximum and minimum values; and the second drawing forging ratio can be a point value of 1.41, 1.5, or 1.61, or a range of two of the above point values ​​as the maximum and minimum values.

[0014] The preferred technical solution is that the initial forging temperature of the forging is 1130~1170℃, and the final forging temperature of the forging is 900~940℃.

[0015] Furthermore, the initial forging temperature of the forging is a point value of 1130, 1140, 1150, 1160, or 1170℃, or a range of two of the above points as the maximum and minimum values, and the final forging temperature of the forging is a point value of 900, 910, 920, 930, or 940℃, or a range of two of the above points as the maximum and minimum values.

[0016] A preferred technical solution is that the annealing step includes: The forging is first held at 485~515℃ for 2.5~3.5h, then heated to 770~790℃ at a heating rate of no more than 80℃ / h, held at a temperature of no less than 4.5h / 100mm of effective cross section of the forging, and then cooled to below 500℃ at a cooling rate of no more than 30℃ / h before being air-cooled.

[0017] Furthermore, the time for which the forging is first held at 485~515℃ can be selected as 2.5, 3, or 3.5 hours, or as a range of the above two values ​​as the maximum and minimum values.

[0018] The preferred technical solution is that the normalizing step includes: The forging is first heated to 635~665℃ and held for 2~3 hours, then heated to 1035~1065℃ and held for 2.9~4.4 hours / 100mm of effective forging thickness before air cooling.

[0019] Furthermore, the forging is first heated to 635, 645, 655, or 665°C, or a range of two of these values ​​as the maximum and minimum values, and held at this temperature for 2-3 hours. Then, it is heated to 1035, 1045, 1055, or 1065°C, or a range of two of these values ​​as the maximum and minimum values. Depending on the effective thickness of the forging, the temperature can be selected as 2.9h / 100mm, 3.2h / 100mm, 3.6h / 100mm, 3.8h / 100mm, 4.1h / 100mm, or 4.4h / 100mm, or a range of two of these values ​​as the maximum and minimum values, held at this temperature, and then air-cooled.

[0020] A preferred technical solution is that the tempering step includes: The forging is heated to 715~745℃, held at that temperature for an effective thickness of 6.3~7.8h / 100mm, and then air-cooled.

[0021] Furthermore, the forging is heated to 715, 725, 735, 745℃ or a range of two of the above points as the maximum and minimum values, and then air-cooled after being kept at the effective thickness of the forging 6.3, 6.6, 6.9, 7.3, 7.8h / 100mm or a range of two of the above points as the maximum and minimum values.

[0022] The preferred technical solution is to air-cool the forging to 190~240℃ and then temper it.

[0023] Furthermore, the forging is air-cooled to 190, 200, 210, 220, 230, 240°C or a range of the above two points as the maximum and minimum values, and then tempered.

[0024] The advantages and beneficial effects of this invention are as follows: This invention relates to a production method for forged tee fittings for ultra-supercritical units (F91). Based on martensitic heat-resistant alloy steel of grade ASTM A182F91, the method improves the high-temperature mechanical properties of the forgings by increasing the nitrogen (N) content and limiting the mass ratio of N to Al. This production system reduces production time by air-cooling the forgings to a suitable temperature followed by tempering, thus maintaining the forgings' high-temperature properties essentially unchanged. Attached Figure Description

[0025] Figure 1 This is a front view of the forged tee for the F91 ultra-supercritical unit produced in Example 1; Figure 2 This is a side view of the forged tee for the ultra-supercritical unit F91 produced in Example 1. Detailed Implementation

[0026] The specific embodiments of the present invention will be further described below with reference to examples. These examples are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0027] 1. Examples and Comparative Examples Example 1

[0028] The forged tee for the F91 ultra-supercritical unit in Example 1 consists of the following components by weight percentage: C: 0.11%, Si: 0.36%, Mn: 0.4%, P: 0.008%, S: 0.002%, Ni: 0.071%, Cr: 8.39%, Nb: 0.071%, Cu: 0.033%, Mo: 0.9%, Al: 0.011%, Ti: 0.003%, N: 0.061%, V: 0.21%, Zr: 0.005%, with the balance being Fe and unavoidable impurities.

[0029] The manufacturing process of the F91 forged tee for ultra-supercritical unit in Example 1 includes the following steps: S1: 16T octagonal ingots retain risers and sprues, with a total length of 2249mm. After loading into the furnace, they are heated to 300℃ at a heating rate of 45℃ / h and held for 4 hours. They are then heated to 600℃ at a heating rate of 45℃ / h and held for 4 hours. Finally, they are heated to 1000℃ at a heating rate of 75℃ / h and held for 4 hours. Finally, they are heated to 1180℃ at a heating rate of 75℃ / h and held for 6 hours. S2: The sprue and riser are removed by hot cutting with clamps, and the billet length is 2300mm. S3: The billet is upset using a 5000T hydraulic press. Before upseting, the surface and core temperatures of the billet are measured to be 1140℃. The billet is first upset to a length of 1145mm, a width of 1145mm, and a height of 1300mm. Then it is stretched to a length of 974mm, a width of 974mm, and a height of 1800mm. At this time, the surface temperature of the billet is measured to be 953℃. S4: Reheat the billet in the furnace until the surface and core temperatures of the billet are both 1180℃; S5: The billet is upset and drawn using a 5000T hydraulic press. Before upset drawing, the surface and core temperatures of the billet are measured to be 1152℃. The billet is first upset to a length of 1306mm, a width of 1306mm, and a height of 1000mm, and then drawn to a length of 1065mm, 1065mm, and 1507mm. At this time, the surface temperature of the billet is measured to be 974℃. S6: Reheat the billet in the furnace until the surface and core temperatures of the billet are both 1180℃; S7: Hammer and trim the four sides of the forging to make its surface flat, each side straight and perpendicular to each other. The dimensions of the trimmed forging are 1510mm in length, 803mm in width and 1507mm in height. S8: Punch a hole in the billet to obtain a hole with an inner diameter of 400mm. At this time, the billet temperature is measured to be 923℃. S9: After the forging is loaded into the furnace, it is furnace cooled to 500℃ and held for 3 hours. Then it is heated to 780℃ at a heating rate of 76℃ / h and held for 36 hours. Finally, it is cooled to 495℃ at a cooling rate of 28℃ / h and then removed from the furnace and air cooled. S10: Rough machining of forgings; S11: The forging is returned to the furnace and heated to 650℃ at a heating rate of 90℃ / h, held for 2.5h, then heated to 1050℃ at a heating rate of 90℃ / h, held for 15h, and finally air-cooled. S12: After air cooling to 200℃, the forging is returned to the furnace and heated to 730℃ at a heating rate of 90℃ / h, held at that temperature for 29h, and then air cooled.

[0030] Example 2

[0031] The forged tee for ultra-supercritical unit F91 in Example 2 is based on Example 1, except that the forged tee for ultra-supercritical unit F91 in Example 2 is composed of the following components by weight percentage: C: 0.11%, Si: 0.32%, Mn: 0.41%, P: 0.006%, S: 0.001%, Ni: 0.065%, Cr: 8.33%, Nb: 0.073%, Cu: 0.035%, Mo: 0.93%, Al: 0.015%, Ti: 0.004%, N: 0.062%, V: 0.2%, Zr: 0.006%, with the balance being Fe and unavoidable impurities.

[0032] Example 3

[0033] The forged tee for the ultra-supercritical unit F91 in Example 3 is based on Example 2, except that in S12: after the forging is air-cooled to 250°C, it is returned to the furnace and heated to 730°C at a heating rate of 90°C / h, held for 29 hours, and then air-cooled.

[0034] Example 4

[0035] The forged tee for the ultra-supercritical unit F91 in Example 4 is based on Example 3, except that in S12: after the forging is air-cooled to 150°C, it is returned to the furnace and heated to 730°C at a heating rate of 90°C / h, then held for 29 hours and air-cooled.

[0036] Comparative Example The comparative ultra-supercritical unit F91 forged tee is based on Example 1, except that the comparative ultra-supercritical unit F91 forged tee consists of the following components by weight percentage: C: 0.10%, Si: 0.29%, Mn: 0.42%, P: 0.003%, S: 0.002%, Ni: 0.095%, Cr: 8.44%, Nb: 0.075%, Cu: 0.021%, Mo: 0.96%, Al: 0.019%, Ti: 0.003%, N: 0.07%, V: 0.20%, Zr: 0.007%, balance Fe and unavoidable impurities.

[0037] 2. Performance test results of the examples and comparative examples

[0038] 3. Performance Results Analysis of Examples and Comparative Examples Example 1 and the comparative example show that a higher nitrogen content is beneficial to improving the mechanical properties of forgings at high temperatures.

[0039] Examples 1 and 2 show that setting the mass ratio of N to Al within a suitable range is beneficial to improving the mechanical properties of forgings at high temperatures.

[0040] Examples 1, 3, and 4 show that air cooling of forgings to a suitable temperature followed by tempering helps reduce production time while maintaining the high-temperature properties of the forgings essentially unchanged.

[0041] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for producing a forged tee for an ultra-supercritical unit F91, characterized in that, The process includes sequential steps of pre-forging heating, forging, annealing, rough turning, normalizing, and tempering. The forging is made of martensitic heat-resistant alloy steel of type ASTM A182F91, and its composition by mass percentage is: C: 0.08%~0.12%, Si: 0.2%~0.5%, Mn: 0.3%~0.6%, P≤0.015%, S≤0.005%, Ni≤0.4%, Cr: 8%~9.5%, Nb: 0.06%~0.08%, Cu≤0.3%, Mo: 0.85%~1.05%, Al≤0.02%, Ti≤0.01%, N: 0.055%~0.068%, V: 0.18%~0.22%, Zr≤0.01%, with the balance being Fe and unavoidable impurities; The mass of the raw material heated before forging is 15~30t.

2. The production method of the forged tee for an ultra-supercritical unit F91 according to claim 1, characterized in that, In the composition of the martensitic heat-resistant alloy steel, the mass ratio of nitrogen (N) to al is greater than 5.

3. The production method of the forged tee for an ultra-supercritical unit F91 according to claim 1, characterized in that, The pre-forging heating step includes: S00: The forging is heated to 280~310℃ at a heating rate of no more than 50℃ / h and held for 3.5~4.5h; S01: The forging is heated to 580~610℃ at a heating rate of no more than 50℃ / h and held at that temperature for 3.5~4.5h; S02: The forging is heated to 980~1010℃ at a heating rate of no more than 80℃ / h and held at that temperature for 3.5~4.5h; S03: The forging is heated to 1170~1200℃ at a heating rate of no more than 80℃ / h and held for 5.5~6.5h.

4. The production method of the forged tee for an ultra-supercritical unit F91 according to claim 1, characterized in that, The total forging ratio of the forging is above 6.

5. The method for producing the F91 forged tee for an ultra-supercritical unit according to claim 4, characterized in that, The forging process includes two alternating upsetting and two drawing operations. The forging ratio for the first upsetting is 1.67 to 1.87, the forging ratio for the first drawing is 1.28 to 1.48, the forging ratio for the second upsetting is 1.7 to 1.9, and the forging ratio for the second drawing is 1.41 to 1.

61.

6. The method for producing the F91 forged tee for an ultra-supercritical unit according to claim 1, characterized in that, The initial forging temperature of the forging is 1130~1170℃, and the final forging temperature of the forging is 900~940℃.

7. The method for producing the F91 forged tee for an ultra-supercritical unit according to claim 1, characterized in that, The annealing step includes: The forging is first held at 485~515℃ for 2.5~3.5h, then heated to 770~790℃ at a heating rate of no more than 80℃ / h, held at a temperature of no less than 4.5h / 100mm of effective cross section of the forging, and then cooled to below 500℃ at a cooling rate of no more than 30℃ / h before being air-cooled.

8. The method for producing the F91 forged tee for an ultra-supercritical unit according to claim 1, characterized in that, The normalizing step includes: The forging is first heated to 635~665℃ and held for 2~3 hours, then heated to 1035~1065℃ and held for 2.9~4.4 hours / 100mm of effective forging thickness before air cooling.

9. The method for producing the F91 forged tee for an ultra-supercritical unit according to claim 8, characterized in that, The tempering step includes: The forging is heated to 715~745℃, held at that temperature for an effective thickness of 6.3~7.8h / 100mm, and then air-cooled.

10. The method for producing the F91 forged tee for an ultra-supercritical unit according to claim 9, characterized in that, The forgings are air-cooled to 190~240℃ and then tempered.

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