Preparation method of GH4698 alloy bar for improving room-temperature tensile property and impact property

Abstract

The invention discloses a preparation method of a GH4698 alloy bar for improving room temperature and impact performance. The preparation method comprises the following steps: preparing a high-temperature alloy ingot by adopting a vacuum induction and vacuum self-consumption double-vacuum melting mode; and the bar with the specification of phi 200mm is prepared by adopting a high-temperature homogenization and fast forging forming mode. According to the method, the high-performance GH4698 bar is creatively prepared by optimizing the Ce element content, purifying the impurity content of the grain boundary, not weakening the pinning effect of grain boundary carbide, reducing the crack cracking tendency of the grain boundary and remarkably improving the bonding strength of the grain boundary through the mode of double vacuum smelting, homogenization and fast forging forming; the problem that the warm tensile property and the impact property of the current GH4698 bar do not meet the technical requirements is solved.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal processing technology, specifically relating to a method for preparing GH4698 alloy bars with improved room temperature tensile and impact properties. Background Technology

[0002] GH4698 alloy is a typical age-hardening nickel-based superalloy with Al, Ti, and Mo as strengthening elements. It possesses excellent microstructural stability, corrosion resistance, and high-temperature mechanical properties, making it suitable for use in aerospace components such as turbine disks, guide vanes, and fasteners operating below 750℃. To ensure the safety of these components during service, OEMs impose extremely high requirements on the mechanical properties of forged raw materials, especially tensile and impact properties. Research indicates that tensile and impact properties are primarily influenced by alloy composition, microstructure, and strengthening phases, with the alloy composition essentially determining the overall performance.

[0003] To purify grain boundaries, reduce the tendency for intergranular cracking, and improve oxidation and corrosion resistance, rare earth elements such as Ce are typically added during alloy production to achieve excellent high-temperature performance. However, improper control can significantly reduce room-temperature tensile and impact properties. Therefore, it is necessary to control the content of rare earth elements such as Ce to obtain superior overall performance. Thus, controlling the Ce content to improve the room-temperature tensile and impact properties of GH4698 alloy bars is the primary problem to be solved. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing GH4698 alloy bars with improved room temperature tensile and impact properties, thereby solving the problem of poor room temperature tensile and impact properties of existing GH4698 alloy bars.

[0005] The technical solution adopted in this invention is a method for preparing GH4698 alloy bars with improved room temperature tensile and impact properties. The specific operation steps are as follows:

[0006] Step 1: High-temperature alloy ingots are prepared using a dual vacuum melting method of vacuum induction and vacuum self-consumption. Step 2: Prepare alloy bars using a temperature homogenization + rapid forging method.

[0007] The invention is further characterized in that, Preferably, the specifications of the double vacuum melting in S1 are changed to Φ430 (±20) mm-Φ508 (±20) mm; Φ430 is the vacuum induction specification and Φ508 is the vacuum self-consumption specification.

[0008] Preferably, the composition of the ingot prepared by double vacuum melting in S1 is: C: 0.040%~0.060%, Cr: 13.50%~15.00%, Mo: 2.90%~3.10%, Nb: 2.00%~2.10%, Ti: 2.55%~2.65%, Al: 1.55%~1.70%, Zr: 0.03%~0.04%, B: 0.003%~0.004%, Mg: 0.01~0.03%, Ce: 0.0010~0.0020%, Fe≤1.0%, and the remainder is Ni.

[0009] Preferably, in the vacuum induction melting process of S1, the raw materials are added in the following order: Ni, C, Cr, Mo, Nb, Ti, Al, Zr, B, Mg, Ce. After the composition before the furnace is tested and found to be qualified, the casting temperature is tested to meet the requirements of 1450~1510℃. After temperature measurement, the holding power is controlled at 400~500kW. Before casting, the furnace is purged with argon to 200~300hPa. After Mg is completely melted, Ce is added. After all materials are completely melted, stirring is continued for 5~15 minutes, followed immediately by casting. Electric casting is used. During the casting process, the holding power is controlled from 400~500kW initially to 800~120kW and maintained until the casting is completed.

[0010] Preferably, after the induction casting is completed in step S1, the ingot is vacuum cooled for 30-60 minutes, while the annealing furnace is heated to 900℃~1100℃ and held at that temperature. After the cooling time is reached, the induction casting mold chamber is emptied, the ingot is removed and placed into the annealing furnace as soon as possible, and the holding time is 6-10 hours. After the holding time is completed, the ingot is cooled with the furnace to below 600℃ and then furnace cooled.

[0011] Preferably, in step S1, the visible oxide scale is removed by using a lathe within the circumferential area of ​​the induction ingot surface. The amount of removal on one side is ≥6mm. The removal is carried out until there is no oxide scale or pores on the surface. The electrode head and tail ends are cleaned with a handheld grinder until 100% of the area shows a metallic luster. At this point, the induction ingot becomes a consumable remelting electrode.

[0012] Preferably, in step S1, the consumable electrode undergoes vacuum consumable remelting. The melting rate is controlled within the range of 3.5–4.5 kg / min, and the droplet parameters are controlled within the range of 5–15 1 / s. Helium is used for cooling during the melting process, with a He flow rate of 0.10–0.30 L / min. After the ingot melting is completed, it is cooled under vacuum for 3 hours before being demolded. After demolding, the ingot is sawn off at both ends by 50–100 mm.

[0013] Preferably, the temperature range for high-temperature homogenization in S2 is 1150~1200℃, and the holding time is 30~40h; Preferably, in S2, the rapid forging starting temperature is 1160~1190℃, the deformation is 20~25%, and the starting process involves 3 upsetting and 3 drawing. The initial forging temperature is >1050℃, and the final forging temperature is >950℃. Preferably, in S2, the rapid forging temperature is 1050~1100℃, the deformation amount is 35~40%, the deformation rate is 20~60mm / s, the initial forging temperature is >950℃, and the final forging temperature is >850℃; Preferably, after sawing off 200-300mm rotten ends from both ends of the bar in S2, transverse room temperature tensile and impact test blanks are taken at the R / 2 position. The test blanks are then processed into finished products after heat treatment at 1110℃ / 8h, AC+1000℃ / 4h, AC+775℃ / 16h, and AC, and evaluated according to the relevant national standards.

[0014] Compared with the prior art, the beneficial effects of the present invention are: Compared with the traditional method of producing small-sized Ti55531 titanium alloy bars, this invention creatively proposes to optimize the Ce element content, purify the impurity content of grain boundaries, and reduce the tendency of grain boundary cracking without weakening the pinning effect of grain boundary carbides, thereby significantly improving the bonding strength of grain boundaries. This improves the room temperature tensile and impact properties of high-temperature alloys. High-performance GH4698 bars are prepared by "double vacuum smelting + homogenization + rapid forging", which solves the problem that the current GH4698 bars do not meet the technical requirements for room temperature tensile and impact properties. Detailed Implementation

[0015] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] Example 1 The present invention provides a method for preparing GH4698 alloy bars with improved room temperature and impact properties, comprising the following steps: S1. High-temperature alloy ingots are prepared using a dual vacuum melting method of "vacuum induction + vacuum self-consumption". Preferably, the specifications of the double vacuum melting in S1 are Φ430 (±20) mm-Φ508 (±20) mm.

[0017] Preferably, the composition of the ingot prepared by double vacuum melting in S1 is: C: 0.040%~0.060%, Cr: 13.50%~15.00%, Mo: 2.90%~3.10%, Nb: 2.00%~2.10%, Ti: 2.55%~2.65%, Al: 1.55%~1.70%, Zr: 0.03%~0.04%, B: 0.003%~0.004%, Mg: 0.01~0.03%, Ce: 0.0050%, Fe≤1.0%, with the remainder being Ni.

[0018] Preferably, in the vacuum induction melting process of S1, the raw materials are added in the following order: Ni, C, Cr, Mo, Nb, Ti, Al, Zr, B, Mg, Ce. After the composition before the furnace is tested and found to be qualified, the casting temperature is tested to meet the requirements of 1450~1510℃. After temperature measurement, the holding power is controlled at 400~500kW. Before casting, the furnace is purged with argon to 200~300hPa. After Mg is completely melted, Ce is added. After all materials are completely melted, stirring is continued for 5~15 minutes, followed immediately by casting. Electric casting is used. During the casting process, the holding power is controlled from 400~500kW initially to 800~120kW and maintained until the casting is completed.

[0019] Preferably, after the induction casting is completed in step S1, the ingot is vacuum cooled for 30-60 minutes, while the annealing furnace is heated to 900℃~1100℃ and held at that temperature. After the cooling time is reached, the induction casting mold chamber is emptied, the ingot is removed and placed into the annealing furnace as soon as possible, and the holding time is 6-10 hours. After the holding time is completed, the ingot is cooled with the furnace to below 600℃ and then furnace cooled.

[0020] Preferably, in step S1, the visible oxide scale is removed by using a lathe within the circumferential area of ​​the induction ingot surface. The amount of removal on one side is ≥6mm. The removal is carried out until there is no oxide scale or pores on the surface. The electrode head and tail ends are cleaned with a handheld grinder until 100% of the area shows a metallic luster. At this point, the induction ingot becomes a consumable remelting electrode.

[0021] Preferably, in step S1, the consumable electrode undergoes vacuum consumable remelting. The melting rate is controlled within the range of 3.5–4.5 kg / min, and the droplet parameters are controlled within the range of 5–15 1 / s. Helium is used for cooling during the melting process, with a He flow rate of 0.10–0.30 L / min. After the ingot melting is completed, it is cooled under vacuum for 3 hours before being demolded. After demolding, the ingot is sawn off at both ends by 50–100 mm.

[0022] S2. Φ200mm bars are prepared using the "high temperature homogenization + fast forging" method. Preferably, the temperature range for high-temperature homogenization in S2 is 1150~1200℃, and the holding time is 30~40h; Preferably, in S2, the rapid forging starting temperature is 1160~1190℃, the deformation is 20~25%, and the starting process involves 3 upsetting and 3 drawing. The initial forging temperature is >1050℃, and the final forging temperature is >950℃. Preferably, in S2, the rapid forging temperature is 1050~1100℃, the deformation amount is 35~40%, the deformation rate is 20~60mm / s, the initial forging temperature is >950℃, and the final forging temperature is >850℃; Preferably, after sawing off 200-300mm rotten ends from both ends of the bar in S2, transverse room temperature tensile and impact test blanks are taken at the R / 2 position. The test blanks are then processed into finished products after heat treatment at 1110℃ / 8h, AC+1000℃ / 4h, AC+775℃ / 16h, and AC, and evaluated according to the relevant national standards.

[0023] Table 1. Room temperature tensile and impact properties of typical high Ce rods prepared in Example 1

[0024] The 200mm GH4698 alloy bar prepared using the above method had a Ce element test result of 39ppm. The room temperature tensile and impact properties of the bar head and tail are shown in Table 1. It can be seen that, compared with the standard requirements, there are obviously unqualified conditions.

[0025] Example 2 The method for preparing GH4698 alloy bars with improved room temperature tensile and impact properties according to the present invention includes the following steps: S1. High-temperature alloy ingots are prepared using a dual vacuum melting method of "vacuum induction + vacuum self-consumption". Preferably, the specifications of the double vacuum melting in S1 are Φ430 (±20) mm-Φ508 (±20) mm.

[0026] Preferably, the composition of the ingot prepared by double vacuum melting in S1 is: C: 0.040%~0.060%, Cr: 13.50%~15.00%, Mo: 2.90%~3.10%, Nb: 2.00%~2.10%, Ti: 2.55%~2.65%, Al: 1.55%~1.70%, Zr: 0.03%~0.04%, B: 0.003%~0.004%, Mg: 0.02%, Ce: 0.0010~0.0020%, Fe≤1.0%, and the remainder is Ni.

[0027] Preferably, in the vacuum induction melting process of S1, the raw materials are added in the following order: Ni, C, Cr, Mo, Nb, Ti, Al, Zr, B, Mg, Ce. After the composition before the furnace is tested and found to be qualified, the casting temperature is tested to meet the requirements of 1450~1510℃. After temperature measurement, the holding power is controlled at 400~500kW. Before casting, the furnace is purged with argon to 200~300hPa. After Mg is completely melted, Ce is added. After all materials are completely melted, stirring is continued for 5~15 minutes, followed immediately by casting. Electric casting is used. During the casting process, the holding power is controlled from 400~500kW initially to 800~120kW and maintained until the casting is completed.

[0028] Preferably, after the induction casting is completed in step S1, the ingot is vacuum cooled for 30-60 minutes, while the annealing furnace is heated to 900℃~1100℃ and held at that temperature. After the cooling time is reached, the induction casting mold chamber is emptied, the ingot is removed and placed into the annealing furnace as soon as possible, and the holding time is 6-10 hours. After the holding time is completed, the ingot is cooled with the furnace to below 600℃ and then furnace cooled.

[0029] Preferably, in step S1, the visible oxide scale is removed by using a lathe within the circumferential area of ​​the induction ingot surface. The amount of removal on one side is ≥6mm. The removal is carried out until there is no oxide scale or pores on the surface. The electrode head and tail ends are cleaned with a handheld grinder until 100% of the area shows a metallic luster. At this point, the induction ingot becomes a consumable remelting electrode.

[0030] Preferably, in step S1, the consumable electrode undergoes vacuum consumable remelting. The melting rate is controlled within the range of 3.5–4.5 kg / min, and the droplet parameters are controlled within the range of 5–15 1 / s. Helium is used for cooling during the melting process, with a He flow rate of 0.10–0.30 L / min. After the ingot melting is completed, it is cooled under vacuum for 3 hours before being demolded. After demolding, the ingot is sawn off at both ends by 50–100 mm.

[0031] S2. Φ200mm bars are prepared using the "high temperature homogenization + fast forging" method. Preferably, the temperature range for high-temperature homogenization in S2 is 1150~1200℃, and the holding time is 30~40h; Preferably, in S2, the rapid forging starting temperature is 1160~1190℃, the deformation is 20~25%, and the starting process involves 3 upsetting and 3 drawing. The initial forging temperature is >1050℃, and the final forging temperature is >950℃. Preferably, in S2, the rapid forging temperature is 1050~1100℃, the deformation amount is 35~40%, the deformation rate is 20~60mm / s, the initial forging temperature is >950℃, and the final forging temperature is >850℃; Preferably, after sawing off 200-300mm rotten ends from both ends of the bar in S2, transverse room temperature tensile and impact test blanks are taken at the R / 2 position. The test blanks are then processed into finished products after heat treatment at 1110℃ / 8h, AC+1000℃ / 4h, AC+775℃ / 16h, and AC, and evaluated according to the relevant national standards.

[0032] Table 2. Room temperature tensile and impact properties of typical low-Ce bars prepared in Example 2

[0033] The 200mm GH4698 alloy bar prepared using the above method had a Ce element content of 7 ppm. Table 2 shows the room temperature tensile and impact properties of the bar's head and tail. It can be seen that the properties significantly exceed the standard requirements and have a high margin of safety. Therefore, the standard requirements are fully met.

[0034] Experimental results: The 200mm GH4698 alloy bar obtained in Example 2 has a lower Ce content, higher room temperature tensile properties and impact properties at both ends, and both meet the standard requirements.

[0035] Conclusion: This invention creatively proposes a method to prepare high-performance GH4698 bars by optimizing the Ce element content and using "double vacuum smelting + homogenization + rapid forging", which solves the problem that the current GH4698 bars do not meet the technical requirements for temperature tensile and impact properties.

[0036] Example 3 The present invention provides a method for preparing GH4698 alloy bars with improved room temperature and impact properties, comprising the following steps: S1. High-temperature alloy ingots are prepared using a dual vacuum melting method of "vacuum induction + vacuum self-consumption". The specifications for double vacuum melting in S1 have evolved to Φ430 (±20) mm - Φ508 (±20) mm.

[0037] Preferably, the ingot composition prepared by double vacuum melting in S1 is: C: 0.05%, Cr: 14%, Mo: 3%, Nb: 2.0%, Ti: 2.55%, Al: 1.70%, Zr: 0.04%, B: 0.004%, Mg: 0.01%, Ce: 0.001%, Fe ≤ 1.0%, and the remainder is Ni.

[0038] In the vacuum induction melting process described in S1, the raw materials are added in the following order: Ni, C, Cr, Mo, Nb, Ti, Al, Zr, B, Mg, Ce. After the pre-furnace composition is tested and found to be qualified, the casting temperature is tested to meet the requirements of 1450~1510℃. After temperature measurement, the holding power is controlled at 400~500kW. Before casting, the furnace is purged with argon to 200~300hPa. After Mg is completely melted, Ce is added. After all materials are completely melted, stirring continues for 5~15 minutes, followed immediately by casting. Electric casting is used. During the casting process, the holding power is controlled from 500kW initially to 120kW and maintained until the casting is completed.

[0039] Preferably, after the induction casting is completed in step S1, the ingot is vacuum cooled for 50 minutes, and the annealing furnace is heated to 1100°C and held at that temperature. After the cooling time is reached, the induction casting mold chamber is emptied, the ingot is removed and placed into the annealing furnace as soon as possible, and the holding time is 8 hours. After the holding time is completed, the ingot is cooled to below 600°C in the furnace and then furnace cooled.

[0040] Preferably, in step S1, the visible oxide scale is removed by using a lathe within the circumferential area of ​​the induction ingot surface. The amount of removal on one side is ≥6mm. The removal is carried out until there is no oxide scale or pores on the surface. The electrode head and tail ends are cleaned with a handheld grinder until 100% of the area shows a metallic luster. At this point, the induction ingot becomes a consumable remelting electrode.

[0041] Preferably, in step S1, the consumable electrode undergoes vacuum consumable remelting. The melting rate is controlled within a range of 4 kg / min, and the droplet parameter range is 10 1 / s. The melting process is cooled by helium gas with a He flow rate of 0.20 L / min. After the ingot melting is completed, it is cooled under vacuum for 3 hours before being demolded. After demolding, the ingot is sawn off at both ends by 80 mm.

[0042] S2. Φ200mm bars are prepared using the "high temperature homogenization + fast forging" method. The temperature range for high-temperature homogenization in S2 is 1200℃, and the holding time is 40h. In S2, the rapid forging starting temperature is 1160℃, the deformation is 20%, and the starting process involves 3 upsetting and 3 drawing. The initial forging temperature is >1050℃, and the final forging temperature is >950℃. In S2, the rapid forging temperature is 1050~1100℃, the deformation amount is 35~40%, the deformation rate is 20~60mm / s, the initial forging temperature is >950℃, and the final forging temperature is >850℃; After the ends of the bar stock in S2 are sawn off to a thickness of 200-300 mm, transverse room temperature tensile and impact test specimens are taken at the R / 2 position. The specimens are then processed into finished products after heat treatment at 1110℃ / 8h, AC+1000℃ / 4h, AC+775℃ / 16h, and AC, and evaluated according to the relevant national standards.

[0043] The 200mm GH4698 alloy bar prepared using the above method had a Ce element test result of 39ppm. The room temperature tensile and impact properties of the bar head and tail are shown in Table 1. It can be seen that, compared with the standard requirements, there are obviously unqualified conditions.

[0044] Example 4 The method for preparing GH4698 alloy bars with improved room temperature tensile and impact properties according to the present invention includes the following steps: S1. High-temperature alloy ingots are prepared using a dual vacuum melting method of "vacuum induction + vacuum self-consumption". Preferably, the specifications of the double vacuum melting in S1 are Φ430 (±20) mm-Φ508 (±20) mm.

[0045] Preferably, the ingot composition prepared by double vacuum melting in S1 is: C: 0.060%, Cr: 13.50%, Mo: 2.90%, Nb: 2.10%, Ti: 2.55%, Al: 1.6%, Zr: 0.03%, B: 0.004%, Mg: 0.01%, Ce: 0.0020%, Fe ≤ 1.0%, and the remainder is Ni.

[0046] Preferably, in the vacuum induction melting process of S1, the raw materials are added in the following order: Ni, C, Cr, Mo, Nb, Ti, Al, Zr, B, Mg, Ce. After the composition before the furnace is tested and found to be qualified, the casting temperature is tested to meet 1500℃. After temperature measurement, the holding power is controlled at 450kW. Before casting, the furnace is purged with argon to 300hPa. After Mg is completely melted, Ce is added. After all materials are completely melted, stirring continues for 5-15 minutes, followed immediately by casting. Electric casting is used. During the casting process, the holding power is controlled from 400-500kW initially to 800-120kW, and maintained until the casting is completed.

[0047] Preferably, after the induction casting is completed in step S1, the ingot is vacuum cooled for 30 minutes, and the annealing furnace is heated to 1000°C and held at that temperature. After the cooling time is reached, the induction casting mold chamber is emptied, the ingot is removed and placed into the annealing furnace as soon as possible, and the holding time is 10 hours. After the holding time is completed, the ingot is cooled to below 600°C in the furnace and then furnace cooled.

[0048] Preferably, in step S1, the visible oxide scale is removed by using a lathe within the circumferential area of ​​the induction ingot surface. The amount of removal on one side is ≥6mm. The removal is carried out until there is no oxide scale or pores on the surface. The electrode head and tail ends are cleaned with a handheld grinder until 100% of the area shows a metallic luster. At this point, the induction ingot becomes a consumable remelting electrode.

[0049] Preferably, in step S1, the consumable electrode undergoes vacuum consumable remelting. The melting rate is controlled within a range of 3.5 kg / min, and the droplet parameter range is 8 1 / s. Helium is used for cooling during the melting process, with a He flow rate of 0.20 L / min. After the ingot melting is completed, it is cooled under vacuum for 3 hours before being demolded. After demolding, the ingot is sawn off at both ends by 100 mm.

[0050] S2. Φ200mm bars are prepared using the "high temperature homogenization + fast forging" method. The temperature range for high-temperature homogenization in S2 is 1200℃, and the holding time is 40h. In S2, the rapid forging starting temperature is 1180℃, the deformation is 23%, and the starting process involves 3 upsetting and 3 drawing. The initial forging temperature is >1050℃, and the final forging temperature is >950℃. In S2, the rapid forging temperature is 1050~1100℃, the deformation amount is 35~40%, the deformation rate is 20~60mm / s, the initial forging temperature is >950℃, and the final forging temperature is >850℃; After the ends of the bar stock in S2 are sawn off to a thickness of 200-300 mm, transverse room temperature tensile and impact test specimens are taken at the R / 2 position. The specimens are then processed into finished products after heat treatment at 1110℃ / 8h, AC+1000℃ / 4h, AC+775℃ / 16h, and AC, and evaluated according to the relevant national standards.

[0051] Example 5 The method for preparing GH4698 alloy bars with improved room temperature tensile and impact properties according to the present invention includes the following steps: S1. High-temperature alloy ingots are prepared using a dual vacuum melting method of "vacuum induction + vacuum self-consumption". Preferably, the specifications of the double vacuum melting in S1 are Φ430 (±20) mm-Φ508 (±20) mm.

[0052] Preferably, the ingot composition prepared by double vacuum melting in S1 is: C: 0.04%, Cr: 14.50%, Mo: 3.10%, Nb: 2.00%, Ti: 2.60%, Al: 1.55%, Zr: 0.04%, B: 0.003%, Mg: 0.03%, Ce: 0.001%, Fe ≤ 1.0%, and the remainder is Ni.

[0053] Preferably, in the vacuum induction melting process of S1, the raw materials are added in the following order: Ni, C, Cr, Mo, Nb, Ti, Al, Zr, B, Mg, Ce. After the composition before the furnace is tested and found to be qualified, the casting temperature is tested to meet 1500℃. After temperature measurement, the holding power is controlled at 450kW. Before casting, the furnace is purged with argon to 300hPa. After Mg is completely melted, Ce is added. After all materials are completely melted, stirring continues for 5-15 minutes, followed immediately by casting. Electric casting is used. During the casting process, the holding power is controlled from 400-500kW initially to 200kW, and maintained until the casting is completed.

[0054] Preferably, after the induction casting is completed in step S1, the ingot is vacuum cooled for 45 minutes, and the annealing furnace is heated to 900°C and held at that temperature. After the cooling time is reached, the induction casting mold chamber is emptied, the ingot is removed and placed into the annealing furnace as soon as possible, and the holding time is 7 hours. After the holding time is completed, the ingot is cooled to 560°C with the furnace and then furnace cooled.

[0055] Preferably, in step S1, the visible oxide scale is removed by using a lathe within the circumferential area of ​​the induction ingot surface. The amount of removal on one side is ≥6mm. The removal is carried out until there is no oxide scale or pores on the surface. The electrode head and tail ends are cleaned with a handheld grinder until 100% of the area shows a metallic luster. At this point, the induction ingot becomes a consumable remelting electrode.

[0056] Preferably, in step S1, the consumable electrode undergoes vacuum consumable remelting. The melting rate is controlled within a range of 4 kg / min, and the droplet parameter range is 8 1 / s. Helium is used for cooling during the melting process, with a He flow rate of 0.20 L / min. After the ingot melting is completed, it is cooled under vacuum for 3 hours before being demolded. After demolding, the ingot is sawn 100 mm from both ends.

[0057] S2. Φ200mm bars are prepared using the "high temperature homogenization + fast forging" method. The temperature range for high-temperature homogenization in S2 is 1200℃, and the holding time is 40h. In S2, the rapid forging starting temperature is 1180℃, the deformation is 23%, and the starting process involves 3 upsetting and 3 drawing. The initial forging temperature is >1050℃, and the final forging temperature is >950℃. In S2, the rapid forging temperature is 1050~1100℃, the deformation amount is 35~40%, the deformation rate is 20~60mm / s, the initial forging temperature is >950℃, and the final forging temperature is >850℃; After the ends of the bar stock in S2 are sawn off to a thickness of 200-300 mm, transverse room temperature tensile and impact test specimens are taken at the R / 2 position. The specimens are then processed into finished products after heat treatment at 1110℃ / 8h, AC+1000℃ / 4h, AC+775℃ / 16h, and AC, and evaluated according to the relevant national standards.

[0058] Example 6 The method for preparing GH4698 alloy bars with improved room temperature tensile and impact properties according to the present invention includes the following steps: S1. High-temperature alloy ingots are prepared using a dual vacuum melting method of "vacuum induction + vacuum self-consumption". Preferably, the specifications of the double vacuum melting in S1 are Φ430 (±20) mm-Φ508 (±20) mm.

[0059] Preferably, the ingot composition prepared by double vacuum melting in S1 is: C: 0.060%, Cr: 13.50%, Mo: 2.90%, Nb: 2.10%, Ti: 2.55%, Al: 1.6%, Zr: 0.03%, B: 0.004%, Mg: 0.01%, Ce: 0.002%, Fe ≤ 1.0%, and the remainder is Ni.

[0060] Preferably, in the vacuum induction melting process of S1, the raw materials are added in the following order: Ni, C, Cr, Mo, Nb, Ti, Al, Zr, B, Mg, Ce. After the composition before the furnace is tested and found to be qualified, the casting temperature is tested to meet 1500℃. After temperature measurement, the holding power is controlled at 450kW. Before casting, the furnace is purged with argon to 300hPa. After Mg is completely melted, Ce is added. After all materials are completely melted, stirring continues for 5-15 minutes, followed immediately by casting. Electric casting is used. During the casting process, the holding power is controlled from 400-500kW initially to 800-120kW, and maintained until the casting is completed.

[0061] Preferably, after the induction casting is completed in step S1, the ingot is vacuum cooled for 30 minutes, and the annealing furnace is heated to 1000°C and held at that temperature. After the cooling time is reached, the induction casting mold chamber is emptied, the ingot is removed and placed into the annealing furnace as soon as possible, and the holding time is 10 hours. After the holding time is completed, the ingot is cooled to below 600°C in the furnace and then furnace cooled.

[0062] Preferably, in step S1, the visible oxide scale is removed by using a lathe within the circumferential area of ​​the induction ingot surface. The amount of removal on one side is ≥6mm. The removal is carried out until there is no oxide scale or pores on the surface. The electrode head and tail ends are cleaned with a handheld grinder until 100% of the area shows a metallic luster. At this point, the induction ingot becomes a consumable remelting electrode.

[0063] Preferably, in step S1, the consumable electrode undergoes vacuum consumable remelting. The melting rate is controlled within a range of 3.5 kg / min, and the droplet parameter range is 8 1 / s. Helium is used for cooling during the melting process, with a He flow rate of 0.20 L / min. After the ingot melting is completed, it is cooled under vacuum for 3 hours before being demolded. After demolding, the ingot is sawn off at both ends by 100 mm.

[0064] S2. Φ200mm bars are prepared using the "high temperature homogenization + fast forging" method. The temperature range for high-temperature homogenization in S2 is 1200℃, and the holding time is 40h. In S2, the rapid forging starting temperature is 1180℃, the deformation is 23%, and the starting process involves 3 upsetting and 3 drawing. The initial forging temperature is >1050℃, and the final forging temperature is >950℃. In S2, the rapid forging forming temperature is 1050~1100℃, the deformation amount is 38%, the deformation rate is 40mm / s, the initial forging temperature is >950℃, and the final forging temperature is >850℃. After the ends of the bar stock in S2 are sawn off to a thickness of 200-300 mm, transverse room temperature tensile and impact test specimens are taken at the R / 2 position. The specimens are then processed into finished products after heat treatment at 1110℃ / 8h, AC+1000℃ / 4h, AC+775℃ / 16h, and AC, and evaluated according to the relevant national standards.

[0065] The above description is merely a preferred embodiment of the present invention. The present invention is not limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. Any simple modifications, equivalent variations, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing GH4698 alloy bars with improved room temperature tensile and impact properties, characterized in that: The specific operating steps are as follows: Step 1: High-temperature alloy ingots are prepared using a dual vacuum melting method of vacuum induction and vacuum self-consumption. Step 2: Prepare alloy bars using a temperature homogenization + rapid forging method.

2. The method for preparing GH4698 alloy bars with improved room temperature tensile and impact properties according to claim 1, characterized in that: The ingot composition, by mass percentage, includes: C: 0.040%~0.060%, Cr: 13.50%~15.00%, Mo: 2.90%~3.10%, Nb: 2.00%~2.10%, Ti: 2.55%~2.65%, Al: 1.55%~1.70%, Zr: 0.03%~0.04%, B: 0.003%~0.004%, Mg: 0.01~0.03%, Ce: 0.001~0.002%, Fe≤1.0%, with the remainder being Ni.

3. The method for preparing GH4698 alloy bars with improved room temperature tensile and impact properties according to claim 2, characterized in that: Step 1: The order of adding raw materials in the vacuum induction melting process is as follows: Ni, C, Cr, Mo, Nb, Ti, Al, Zr, B, Mg, Ce. After the composition before the furnace is tested and found to be qualified, the casting temperature is tested to meet the requirements of 1450~1510℃. After temperature measurement, the holding power is controlled at 400~500kW. Before casting, the furnace is filled with argon to 200~300hPa. After Mg is completely melted, Ce is added. After it is completely melted, stirring is continued for 5~15 minutes. Then casting is carried out immediately. Electric casting is used. During the casting process, the holding power is controlled at 400~500kW in the early stage and gradually reduced to 800~120kW, and maintained until the casting is completed.

4. The method for preparing GH4698 alloy bars with improved room temperature tensile and impact properties according to claim 3, characterized in that: After completing the induction casting in step 1, vacuum cool for 30-60 minutes, while simultaneously heating the annealing furnace to 900℃~1100℃ and holding it there. After the cooling time is reached, remove the ingot and place it into the annealing furnace as soon as possible. Hold it there for 6-10 hours. After the holding time is completed, cool the ingot with the furnace to below 600℃ and then furnace cool it.

5. The method for preparing GH4698 alloy bars with improved room temperature tensile and impact properties according to claim 4, characterized in that: In step 1, a lathe is used to remove the visible oxide scale within the circumference of the surface of the induction casting. The amount of removal on one side is ≥6mm. The removal is carried out until there is no oxide scale or pores on the surface. The electrode head and tail end faces are cleaned with a hand-held grinder until 100% of the area shows a metallic luster. At this point, the induction casting becomes a consumable remelting electrode.

6. The method for preparing GH4698 alloy bars with improved room temperature tensile and impact properties according to claim 5, characterized in that: In step 1, the consumable electrode is subjected to vacuum consumable remelting. The melting rate is controlled within the range of 3.5~4.5 kg / min and the droplet parameter range is 5~15 1 / s. The melting process is cooled by helium gas with a He flow rate of 0.10~0.30 L / min. After the ingot melting is completed, it is cooled under vacuum for 3 hours before being demolded. After demolding, the ingot head and tail are sawn off by 50~100 mm.

7. The method for preparing GH4698 alloy bars with improved room temperature tensile and impact properties according to claim 6, characterized in that, In step 2, the temperature range for high-temperature homogenization is 1150~1200℃, and the holding time is 30~40h.

8. The method for preparing GH4698 alloy bars with improved room temperature and impact properties according to claim 7, characterized in that, In step 2, the fast forging opening temperature is 1160~1190℃, the deformation is 20~25%, the opening adopts 3 upsetting and 3 drawing, the initial forging temperature is >1050℃, and the final forging temperature is >950℃.

9. The method for preparing GH4698 alloy rods with improved room temperature and impact properties according to claim 7, characterized in that, In step 2, the rapid forging temperature is 1050~1100℃, the deformation amount is 35~40%, the deformation rate is 20~60mm / s, the initial forging temperature is >950℃, and the final forging temperature is >850℃.

10. The method for preparing GH4698 alloy bars with improved room temperature and impact properties according to claim 7, characterized in that, In step 2, after sawing off 200-300mm of rotten ends from the head and tail of the bar, transverse room temperature tensile and impact test blanks are taken at the R / 2 position. The test blanks are then processed into finished products after heat treatment at 1110℃ / 8h, AC+1000℃ / 4h, AC+775℃ / 16h, and AC.

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