Age hardening type high-temperature alloy hot-rolled bar and method for controlling grain size uniformity of age hardening type high-temperature alloy hot-rolled bar

Abstract

The invention relates to the field of high-temperature alloy materials, in particular to an age hardening type high-temperature alloy hot-rolled bar and a method for controlling grain size uniformity of the age hardening type high-temperature alloy hot-rolled bar, and the age hardening type high-temperature alloy hot-rolled bar comprises, by weight, less than or equal to 0.08% of C, 10%-20% of Cr, 2%-4% of Mo, 1%-2% of Al, 2%-3% of Ti, 1.5%-2.5% of Nb, 0.001%-0.008% of Mg, 0.002%-0.005% of B and the balance Ni and inevitable impurities. According to the method, effective and accurate control over the grain size of the age hardening type high-temperature alloy bar is achieved on the basis of optimizing hot rolling process parameters and adding specific microelements, and therefore the age hardening type high-temperature alloy hot-rolled bar meeting the requirements is prepared.

Description

Technical Field

[0001] The present invention relates to the field of high-temperature alloy materials, and in particular to an age-hardening high-temperature alloy hot-rolled bar and a method for controlling the grain size uniformity of the age-hardening high-temperature alloy hot-rolled bar, and in particular to an age-hardening high-temperature alloy hot-rolled bar with a size not greater than ∅30 mm and a method for controlling the grain size uniformity of the age-hardening high-temperature alloy hot-rolled bar. Background Art

[0002] A certain age-hardening high-temperature alloy has been widely used in aviation, aerospace, energy and other fields due to its excellent high-temperature mechanical properties and oxidation and corrosion resistance. China began to imitate this alloy in the 1980s to develop and produce forging materials for aircraft engines. The grain structure of the forgings is relatively uniform. After standard heat treatment, the grain size is in the range of 2 to 5 levels, 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 marine development, in order to meet the use requirements of high-temperature fasteners, the age-hardening alloy small-size rolled bars have begun to be mass-produced, especially the finished product size is not greater than ∅30mm. However, due to the high degree of alloying of the alloy, its processing performance is poor. During the hot rolling process, the problems of grain growth and uneven grain size often lead to poor high-temperature plasticity of the material.

[0003] At present, the research on the grain size control of rolled bars is more focused on the solution aging treatment of materials (for example, a solution treatment method for uniform grain size of the entire cross-section of a high-temperature alloy forging with application number 202210667268.5; a forging method for refining the grain size of a high-temperature alloy ring forging with application number 201710461401.0). However, the grain size control of rolled bars by this method still has problems such as uneven grain size and abnormal grain growth. The uneven grain size will affect the mechanical properties and corrosion resistance of the material, while the abnormal grain growth will affect the processing performance of the material and the quality of the final product. Moreover, there are few reports on the grain size control of small-sized age-hardening high-temperature alloy bars in the prior art.

[0004] Therefore, how to effectively control the grain size of high-temperature alloy hot-rolled bars, especially small-sized rolled bars, has become a technical problem that needs to be solved urgently. Summary of the invention

[0005] In view of this, the purpose of the present invention is to propose an age-hardening type high-temperature alloy hot-rolled bar and a method for controlling the uniformity of the grain size of the age-hardening type high-temperature alloy hot-rolled bar. The method can effectively control the grain size of small-size age-hardening type high-temperature alloy hot-rolled bars, and plays an important role in promoting subsequent production and processing and improving efficiency. At the same time, it is of great significance to energy conservation and emission reduction and reducing enterprise production costs.

[0006] Specifically, according to one aspect of the present invention, there is provided an age-hardening high-temperature alloy hot-rolled bar, which includes the following components in weight percentage: C≤0.08%, Cr: 10%~20%, Mo: 2%~4%, Al: 1%~2%, Ti: 2%~3%, Nb: 1.5%~2.5%, Mg: 0.001%~0.008%, B: 0.002%~0.005%, and the rest is Ni and unavoidable impurities.

[0007] According to another aspect of the present invention, a method for controlling the grain size uniformity of an age-hardening type high-temperature alloy hot-rolled bar is provided, which comprises the following steps: S10. performing vacuum induction and electroslag remelting composite smelting on an alloy raw material to obtain an electroslag ingot, wherein: the alloy smelting temperature and refining time are controlled in the vacuum induction melting stage, and the remelting current and cooling rate are controlled in the electroslag remelting stage; the alloy raw material includes an alloy raw material containing Mg and B; S20. performing hot rolling pretreatment on the electroslag ingot; S30. performing forging and blanking on the electroslag ingot after the hot rolling pretreatment to obtain a square billet, wherein in the forging and blanking stage, the forging temperature and deformation amount of each pass are controlled; S40. performing hot rolling on the square billet to obtain a hot-rolled rod, wherein in the hot rolling stage, the hot rolling process parameters are controlled according to the grain size requirements; S50. performing regional hot rolling post-treatment on the hot-rolled rod according to the grain size and temperature distribution at different positions to finely control the grain size; and S60. The hot-rolled rod after hot rolling post-treatment is subjected to solid solution aging treatment to accurately control the grain size, thereby obtaining the age-hardening high-temperature alloy hot-rolled rod as described in the present invention.

[0008] In an embodiment of the present invention, step S10 specifically includes: in the vacuum induction melting stage, the alloy raw materials are placed in an induction furnace in proportion, -1 Pa~10 -5 Pa, the melting temperature is controlled to be 1500°C ~ 1700°C, and the refining time is controlled to be 30min ~ 60min; and in the electroslag remelting stage, the remelting current is controlled to be 1000A ~ 1200A, and the cooling rate is controlled to be 3mm / min ~ 5mm / min to obtain the electroslag ingot of a predetermined diameter.

[0009] In an embodiment of the present invention, the method for controlling the grain size uniformity of age-hardening high-temperature alloy hot-rolled bars further comprises: in step S10, adding a grain refiner during the electroslag remelting stage, and the weight percentage of the grain refiner relative to the alloy raw material is: 0.01%~0.05%.

[0010] In an embodiment of the present invention, step S20 specifically includes: performing homogenization treatment on the electroslag ingot at 1200° C. to 1250° C. and keeping the temperature for 2 h to 4 h.

[0011] In an embodiment of the present invention, step S30 specifically includes: S31. Before starting forging: keeping the electroslag ingot at 1150-1200°C for 2h-3h; S32. First forging: performing the first forging at a forging temperature of 1150-1200°C, and controlling the deformation to 20%-30%; S33. Second forging: performing the second forging at a forging temperature of 1050-1150°C, and controlling the deformation to 10%-20%, and multi-directional forging should be adopted during the forging process; S34. Final forging: performing final forging at a final forging temperature of 950-1050°C, and controlling the deformation to 10%-20%, and air cooling after forging; and S35. Repeating step S33 until the electroslag ingot is opened into the square billet of a predetermined size.

[0012] In an embodiment of the present invention, in step S40, the hot rolling process parameters include initial rolling temperature, final rolling temperature, deformation amount and rolling speed, and in step S40, the initial rolling temperature is controlled to be 1100°C~1150°C, the final rolling temperature is 850°C~900°C, the deformation amount is 40%-80%, and the rolling speed is 1m / min~3m / min.

[0013] In an embodiment of the present invention, step S40 specifically includes: S41. heating the square billet to the initial rolling temperature for the first hot rolling, controlling the deformation of the first hot rolling to 30%~50%, and obtaining a bar after initial rolling; S42. heating the bar after initial rolling to the initial rolling temperature again for a second hot rolling, controlling the deformation of the second hot rolling to 10%~30%, and obtaining a bar whose temperature is controlled to the final rolling temperature; and S43. repeating step S42 until a hot-rolled bar of a predetermined diameter is obtained.

[0014] In an embodiment of the present invention, step S50 specifically includes: performing directional and zoned cooling on the hot-rolled rod through a variable frequency cooling water zero-spray system, spraying at a speed of 5 cm / s to 15 cm / s in the horizontal direction and 20 cm / s to 50 cm / s in the vertical direction.

[0015] In an embodiment of the present invention, step S60 specifically includes: solution treatment: keeping the hot-rolled rod after hot rolling treatment at 1080°C~1150°C for 1h~4h; aging treatment: firstly performing the first stage aging at 900°C~1000°C for the hot-rolled rod after solution treatment, keeping it for 2h~3h; then heating to 700°C~800°C for the second stage aging, keeping it for 4h~6h.

[0016] The present invention can obtain age-hardening high-temperature alloy hot-rolled bars that meet the requirements, and realize the grain size control of age-hardening high-temperature alloy hot-rolled bars, especially small-sized age-hardening high-temperature alloy hot-rolled bars, thereby improving the product yield and qualified rate. This has very important guiding significance for domestic enterprises, steel mills and universities engaged in the manufacture of high-temperature alloy products, and will have significant economic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other embodiments can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A flow chart of a method for controlling the grain size uniformity of an age-hardening high-temperature alloy hot-rolled bar according to an embodiment of the present invention; Figure 2 is a schematic diagram of the structure of an age-hardening type high-temperature alloy hot-rolled bar according to an embodiment of the present invention. The age-hardening type high-temperature alloy hot-rolled bar is produced by the method for controlling the grain size uniformity of the age-hardening type high-temperature alloy hot-rolled bar according to the present invention, and its grain size is level 4; and Figure 3 This is a schematic diagram of the organization of an age-hardening high-temperature alloy hot-rolled bar produced by a conventional method in the prior art, and its grain size is level 6. DETAILED DESCRIPTION In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the embodiments of the present invention are further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0019] It should be noted that all expressions using "first" and "second" in the embodiments of the present invention are for distinguishing two non-identical entities with the same name or non-identical parameters. It can be seen that "first" and "second" are only for the convenience of expression and should not be understood as limitations on the embodiments of the present invention. The subsequent embodiments will not explain this one by one.

[0020] In view of the problems existing in the prior art, the present invention proposes an age-hardening high-temperature alloy hot-rolled bar, especially an age-hardening high-temperature alloy hot-rolled bar with a finished product size not greater than ∅30mm, and a method for controlling the grain size of the age-hardening high-temperature alloy hot-rolled bar.

[0021] According to one aspect of the present invention, there is provided an age-hardening high-temperature alloy hot-rolled bar, which comprises the following components in weight percentage: C≤0.08%, Cr: 10%~20%, Mo: 2%~4%, Al: 1%~2%, Ti: 2%~3%, Nb: 1.5%~2.5%, Mg: 0.001%~0.008%, B: 0.002%~0.005%, and the rest is Ni and unavoidable impurities.

[0022] In an embodiment of the present invention, the diameter of the age-hardening high-temperature alloy hot-rolled bar of the present invention is d≤20 mm, and the grain size is: level 2~5, which meets the grain size requirements of small-size rolled alloy bars.

[0023] According to another aspect of the present invention, a method for controlling the uniformity of grain size of an age-hardening high-temperature alloy hot-rolled bar is provided. Figure 1 As shown, it includes the following steps: S10. The alloy raw material is subjected to vacuum induction and electroslag remelting composite smelting to obtain an electroslag ingot, wherein: the alloy melting temperature and refining time are controlled in the vacuum induction melting stage, and the remelting current and cooling rate are controlled in the electroslag remelting stage; the alloy raw material includes an alloy raw material containing Mg and B; S20. The electroslag ingot is subjected to hot rolling pretreatment; S30. Forging and blanking the electroslag ingot after hot rolling pretreatment to obtain a square billet, wherein, in the forging and blanking stage, the forging temperature and deformation amount of each pass are controlled; S40. hot rolling the square billet to obtain a hot-rolled rod, wherein the hot rolling process parameters are controlled according to the grain size requirements during the hot rolling stage; S50. Performing regional hot rolling post-treatment on the hot rolled bar according to the grain size and temperature distribution at different positions to finely control the grain size; and S60. Performing a solution aging treatment on the hot-rolled rod after hot rolling treatment to precisely control the grain size, thereby obtaining an age-hardening high-temperature alloy hot-rolled rod as described in the embodiment of the present invention.

[0024] In an embodiment of the present invention, for the selection of the smelting method, the present invention selects the vacuum induction (VIM) + electroslag remelting (ESR) composite smelting method in step S10. That is, firstly, a high-density induction ingot is obtained in a vacuum environment by VIM smelting, and then the cleanliness and uniformity of the material are further improved by the ESR method, while effectively controlling the grain growth. Among them, in the VIM stage, the alloy smelting temperature and refining time are controlled to ensure that the alloy elements are fully dissolved while avoiding excessive grain growth. In the ESR stage, the grain size is finely controlled by controlling the remelting current and cooling rate.

[0025] In an embodiment of the present invention, in step S10, the alloy raw materials (wt%) may include: 0.013% to 0.019% high-purity graphite block, 18.5% to 24.7% metallic chromium, 58.5% to 65.4% electrolytic nickel, 2.85% to 4.24% molybdenum bars, 2.01% to 4.01% aluminum bars, 0.44% to 0.74% pure titanium raw materials, 5.70% to 7.75% niobium bars, 0.036% to 0.056% ferroboron, and 1.01% to 1.41% nickel-magnesium alloy. The present invention adds a certain amount of B and Mg to the alloy raw materials, and the B and Mg elements mainly regulate the alloy grain size by improving the grain boundary state, wherein: Mg forms a high melting point compound with impurity elements, and B forms a boride.

[0026] In one embodiment, the alloy raw materials (wt %) may include: 0.017% high-purity graphite block, 22.7% metallic chromium, 62.4% electrolytic nickel, 3.24% molybdenum rod, 3.01% aluminum rod, 0.64% pure titanium raw material, 6.75% niobium rod, 0.046% ferroboron, and 1.21% nickel-magnesium alloy.

[0027] In an embodiment of the present invention, step S10 specifically includes: in the vacuum induction melting stage, the alloy raw materials are placed in an induction furnace in proportion, -1 Pa~10 -5 Pa, the melting temperature is controlled to be 1500°C ~ 1700°C, and the refining time is controlled to be 30min ~ 60min to reduce the impurity content in the alloy; and in the electroslag remelting stage, the remelting current is controlled to be 1000A ~ 1200A, and the cooling rate is controlled to be 3mm / min ~ 5mm / min to obtain the electroslag ingot of a predetermined diameter.

[0028] In an embodiment of the present invention, the method for controlling the grain size uniformity of the age-hardening high-temperature alloy hot-rolled bar of the present invention further comprises: in step S10, adding a grain refiner in the electroslag remelting stage, wherein the weight percentage of the grain refiner relative to the alloy raw material is: 0.01% to 0.05%. A trace amount of grain refiner (such as rare earth element Ce) is added during the ESR process to promote nucleation and avoid excessive grain growth.

[0029] In one embodiment, an electroslag ingot with a diameter of ∅360 mm is obtained by VIM+ESR smelting. In other embodiments, electroslag ingots with other diameters or diameter ranges can be obtained as required, which is also within the scope of the present invention.

[0030] In an embodiment of the present invention, step S20 specifically includes: performing homogenization treatment on the electroslag ingot at 1200° C. to 1250° C. and keeping the temperature for 2 h to 4 h to eliminate segregation phases and coarse grains during casting.

[0031] In the embodiment of the present invention, in step 30, the forging temperature and deformation amount of each pass are controlled to prevent excessive growth of grains during the forging process. Specifically, step S30 includes: S31. Before starting forging: keeping the electroslag ingot at 1150-1200°C for 2-3h to ensure that the ingot is fully heated; S32. First forging: performing the first forging at a forging temperature of 1150-1200°C, and controlling the deformation amount to 20%-30%. The internal structure of the alloy is fully broken and the grains are refined through the large deformation amount; S33. Second forging: performing the second forging at a forging temperature of 1050-1150°C, and controlling the deformation amount to 10%-20%. Multi-directional forging should be used during the forging process to increase deformation uniformity and refine grains; S34. Final forging: performing final forging at a final forging temperature of 950-1050°C, and controlling the deformation amount to 10%-20%. After forging, air cooling is performed to prevent grain growth; and S35. Repeating step S33 until the electroslag ingot is opened into a square billet of a predetermined size.

[0032] In one embodiment, a 60 mm×60 mm billet can be obtained through step S30. In other embodiments, billets of other sizes or size ranges can be obtained as needed, which is also within the scope of the present invention.

[0033] In an embodiment of the present invention, in step S40, the hot rolling process parameters include initial rolling temperature, final rolling temperature, deformation and rolling speed, and in step S40, the initial rolling temperature is controlled to be 1100℃~1150℃, the final rolling temperature is 850℃~900℃, the deformation is 40%-80%, and the rolling speed is 1~3m / min. Specifically, step S40 includes: S41. heating the square billet to the initial rolling temperature for the first hot rolling, and the deformation of the first hot rolling is controlled to be 30%~50%, so as to obtain the bar after initial rolling; S42. heating the bar after initial rolling to the initial rolling temperature again for the second hot rolling, and the deformation of the second hot rolling is controlled to be 10%~30%, so as to obtain the bar whose temperature is controlled to the final rolling temperature; and S43. repeating step S42 until a hot rolled bar of a predetermined diameter is obtained.

[0034] In one embodiment, a hot-rolled rod with a diameter of ≤20 mm can be obtained through step S40. In other embodiments, hot-rolled rods with other diameter ranges can be obtained as needed, which is also within the scope of the present invention.

[0035] In the embodiment of the present invention, hot rolling post-treatment is performed in step 50, and directional cooling is performed on the hot-rolled rod after hot rolling, and a variable frequency cooling water zero-spray system (i.e., cooling water zero-time spray system) is used to perform regional cooling according to the grain size and temperature distribution at different positions to achieve precise control of the grain size. Specifically, step S50 includes: directional and zoned cooling of the hot-rolled rod is performed by a variable frequency cooling water zero-spray system, and spraying is performed at a speed of 5-15 cm / s in the horizontal direction and 20-50 cm / s in the vertical direction to achieve precise control of the grain size.

[0036] In an embodiment of the present invention, step 60 performs solution aging treatment on the hot-rolled rod after hot rolling treatment to make the grain size of the hot-rolled rod uniform and fine. Specifically, step S60 includes: solution treatment: keeping the hot-rolled rod after hot rolling treatment at 1080~1150℃ for 1~4h to ensure that the various alloy elements in the alloy are completely dissolved back. The hot-rolled rod is then air-cooled to avoid grain boundary migration and grain growth; aging treatment: first, the hot-rolled rod after solution treatment is aged at 900~1000℃ for the first stage, and kept warm for 2~3h; then the temperature is raised to 700~800℃ for the second stage aging, and kept warm for 4~6h. This stage is to allow the γ' phase and γ'' phase formed in the alloy to be evenly distributed, thereby refining the grains and preventing excessive grain growth.

[0037] The present invention is further described below by means of specific examples.

[0038] In this embodiment, the size and grain size of a certain age-hardening high-temperature alloy hot-rolled bar to be prepared are first introduced. By adjusting the content of the main elements in the alloy, the alloy composition is optimized to ensure the grain size of the final hot-rolled bar. Secondly, the alloy ingot is prepared by a smelting method of vacuum induction + electroslag remelting. Then, the ingot is pre-treated for hot rolling, that is, it is kept warm at a certain temperature for a period of time to eliminate the segregation phase and coarse grains in the ingot structure. The ingot after homogenization is forged and opened to obtain the square billet required for hot rolling. The square billet is then hot-rolled, and the hot-rolled rod that meets the grain size requirements is obtained by controlling the relevant hot rolling process parameters, such as the initial rolling temperature, the final rolling temperature, the deformation amount and the rolling speed. At the same time, the hot-rolled bar is subjected to directional cooling, that is, different areas are controlled to achieve fine control of the grain size. Finally, the hot-rolled bar is subjected to solid solution aging treatment to achieve precise control of the grain size and prepare a hot-rolled bar that meets the requirements.

[0039] Example The diameter requirement of a certain age-hardening high-temperature alloy hot-rolled bar is: d≤20mm, and the grain size requirement is: grade 2~5.

[0040] In order to meet the specifications and grain size requirements of a certain age-hardening high-temperature alloy hot-rolled bar, regulation is carried out from the following aspects: 1. Composition design: C≤0.08%, Cr: 10%~20%, Mo: 2%~4%, Al: 1%~2%, Ti: 2%~3%, Nb: 1.5%~2.5%. In addition, a certain amount of B and Mg are added to the alloy, and the rest is Ni and unavoidable impurities.

[0041] In a certain age-hardening high-temperature alloy hot-rolled bar, B and Mg elements mainly control the alloy grain size by improving the grain boundary state, where Mg forms high-melting point compounds with impurity elements and B forms borides. Therefore, the Mg element is controlled at 0.001%~0.008%, and the B element content is controlled at 0.002%~0.005%.

[0042] 2. Selection of smelting method: Choose the vacuum induction (VIM) + electroslag remelting (ESR) composite smelting method. That is, first obtain a high-density induction ingot in a vacuum environment through VIM smelting, and then use the ESR method to further improve the cleanliness and uniformity of the material, while effectively controlling the grain growth.

[0043] (1) In the VIM stage, the alloy melting temperature and refining time are controlled to ensure that the alloy elements are fully dissolved while avoiding excessive grain growth.

[0044] In the VIM stage, the alloy materials are placed in an induction furnace in proportion and heated in a vacuum environment of 10-3Pa. The melting temperature is 1500~1700℃ to ensure that all elements are fully melted and mixed evenly. The refining time is 30~60min to reduce the impurity content in the alloy.

[0045] (2) In the ESR stage, the grain size is finely controlled by controlling the remelting current and cooling rate.

[0046] In the ESR stage, the remelting current is 1000~1200A and the cooling rate is 3~5mm / min.

[0047] In addition, a trace amount (for example, 0.01%~0.05% of the alloy raw material) of grain refiner (such as rare earth element Ce) is added during the ESR process to promote nucleation and avoid excessive grain growth.

[0048] Through VIM+ESR smelting, ∅360mm electroslag ingot is obtained.

[0049] 3. Hot rolling pretreatment: The electroslag ingot is homogenized at 1200℃~1250℃ and kept warm for 2h~4h to eliminate the segregation phase and coarse grains in the casting.

[0050] 4. Forging process selection: Control the forging temperature and deformation of each pass to prevent excessive grain growth during the forging process.

[0051] (1) Before starting forging, keep the electroslag ingot at 1150-1200℃ for 2-3h to ensure that the ingot is fully heated.

[0052] (2) First forging: Forging temperature 1150~1200℃, deformation 20%~30%. The large deformation allows the internal structure of the alloy to be fully broken and the grains to be refined.

[0053] (3) Second forging: forging temperature 1050 ~ 1150 ℃, deformation control 10% ~ 20%, multi-directional forging should be used during the forging process to increase deformation uniformity and refine grains (4) Final forging: The final forging temperature is 950℃~1050℃, the deformation is controlled at 10%~20%, and air cooling is performed after forging to prevent grain growth.

[0054] (5) Repeat the second forging process until the electroslag ingot is cut into a 60×60 square billet.

[0055] 5. Selection of hot rolling process: initial rolling temperature: 1100~1150℃; final rolling temperature: 850~900℃; deformation: 40%-80%; rolling speed: 1~3m / min.

[0056] (1) The square billet after forging is heated to the initial rolling temperature for the first hot rolling, and the deformation is controlled at 30~50%.

[0057] (2) The bar after the initial rolling is heated again to the initial rolling temperature for secondary hot rolling, and the deformation is controlled at 10~30%. The surface temperature of the bar after the secondary hot rolling is controlled to be the above-mentioned final rolling temperature.

[0058] (3) Repeat the above secondary hot rolling until the hot rolled rod diameter d ≤ 20 mm.

[0059] 6. Post-hot rolling treatment: Directional cooling is carried out on the hot-rolled bars. A variable frequency cooling water zero-spray system is used to carry out regional cooling according to the grain size and temperature distribution at different positions to achieve precise control of the grain size.

[0060] When the hot-rolled bars are cooled in zones, spray at a speed of 5~15cm / s in the horizontal direction and 20~50cm / s in the vertical direction to achieve precise control of the grain size.

[0061] 7. Solution aging treatment: The hot rolled bars are subjected to solution aging treatment to make the bar grain size uniform and fine.

[0062] (1) Solution treatment: The hot-rolled bars of a certain age-hardening high-temperature alloy are kept at 1080-1150°C for 1-4 hours to ensure that the various alloying elements in the alloy are completely dissolved. The bars are then air-cooled to avoid grain boundary migration and grain growth.

[0063] (2) Aging treatment: First, the first stage of aging is carried out at 900~1000℃, and the temperature is kept for 2~3h; then the temperature is raised to 700~800℃ for the second stage of aging, and the temperature is kept for 4~6h. This stage is to allow the γ' phase and γ'' phase formed in the alloy to be evenly distributed, thereby refining the grains and preventing excessive grain growth.

[0064] By the above method, a certain age-hardening high-temperature alloy hot-rolled bar of the present invention is obtained, such as Figure 2 The schematic diagram of its organization is shown, and the grain size is level 4.

[0065] Comparative Example The specific steps of preparing a certain effect hardening type high temperature alloy hot rolled bar by the existing technology are as follows: 1. Raw material preparation Nickel-based alloys: high-purity graphite blocks (C), nickel bars (Ni), metal chromium (Cr), molybdenum bars (Mo), aluminum bars (Al), pure titanium (Ti), Ni-Mg alloys, B-Fe alloys, niobium bars (Nb), etc.

[0066] 2. Ingredient design: C≤0.08%, Cr: 15%~20%, Mo: 2%~5%, Al: 3%~4%, Ti: 1%~3%, Nb: 1.5%~2.5%, and the rest are Ni and unavoidable impurities.

[0067] 3. Smelting: Vacuum Induction Melting (VIM): Vacuum Degree 10 -2 ~10 -6 , heating temperature 1600-1700℃, heating time 2~3h.

[0068] 4. Homogenization treatment: Keep warm at 1150~1200℃ for 12~24h.

[0069] 5. Forging and blanking: Forging temperature is 1050~1150℃, deformation is 50~60%, and forging rate is 5~10mm / s.

[0070] 6. Hot rolling: The initial rolling temperature is 1000~1100℃, the final rolling temperature is 850~950℃, and the reduction per pass is 10~20%.

[0071] 7. Solution treatment: Temperature: 1080~1120℃, time 1~2h, rapid water cooling.

[0072] 8. Timeliness processing: The first stage: 800~850℃ insulation for 4~8h, air cooling The second stage: keep warm at 600~650℃ for 16~24h, air cooling.

[0073] Figure 3 The figure shows the structure diagram of the age-hardening high-temperature alloy hot-rolled bar prepared by the method in the prior art, and the grain size is level 6.

[0074] pass Figure 2 and Figure 3 It can be seen from the comparison that the method of the present invention can obtain an age-hardening high-temperature alloy hot-rolled bar with uniform grain size and no or little abnormal grain growth, which can meet the grain size requirements of 2 to 5 levels for small-sized age-hardening high-temperature alloy hot-rolled bars.

[0075] In summary, the method described in the present invention is based on optimizing hot rolling process parameters and adding specific trace elements to achieve effective and precise control of the grain size of age-hardening high-temperature alloy bars, thereby preparing high-temperature alloy hot-rolled bars that meet the requirements. In addition, it should be understood that the method for controlling the grain size of hot-rolled bars of the present invention is not limited to a certain age-hardening high-temperature alloy, and all methods that use the principles of the present invention to control the grain size are within the scope of patent protection of the present invention.

[0076] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0077] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. An age-hardening high-temperature alloy hot-rolled bar, characterized in that: The invention comprises the following components in weight percentage: C≤0.08%, Cr: 10%~20%, Mo: 2%~4%, Al: 1%~2%, Ti: 2%~3%, Nb: 1.5%~2.5%, Mg: 0.001%~0.008%, B: 0.002%~0.005%, and the rest are Ni and unavoidable impurities.

2. A method for controlling the uniformity of grain size of hot-rolled age-hardening high-temperature alloy bars, characterized in that: The following steps are involved: S10. The alloy raw material is subjected to vacuum induction and electroslag remelting composite smelting to obtain an electroslag ingot, wherein: the alloy melting temperature and refining time are controlled in the vacuum induction melting stage, and the remelting current and cooling rate are controlled in the electroslag remelting stage; the alloy raw material includes an alloy raw material containing Mg and B; S20. The electroslag ingot is subjected to hot rolling pretreatment; S30. Forging and blanking the electroslag ingot after hot rolling pretreatment to obtain a square billet, wherein, in the forging and blanking stage, the forging temperature and deformation amount of each pass are controlled; S40. hot rolling the square billet to obtain a hot-rolled rod, wherein the hot rolling process parameters are controlled according to the grain size requirements during the hot rolling stage; S50. Performing regional hot rolling post-treatment on the hot rolled bar according to the grain size and temperature distribution at different positions to finely control the grain size; and S60. Performing a solution aging treatment on the hot-rolled rod after hot rolling post-treatment to accurately control the grain size, thereby obtaining the age-hardening high-temperature alloy hot-rolled rod as claimed in claim 1.

3. The method according to claim 2, characterized in that Step S10 specifically includes: In the vacuum induction melting stage, the alloy raw materials are placed in an induction furnace according to proportions and heated for 10 -1 Pa~10 -5 Heating under a vacuum environment of 1.5 Pa, controlling the melting temperature to 1500°C ~ 1700°C, and controlling the refining time to 30 min ~ 60 min; and During the electroslag remelting stage, the remelting current is controlled to be 1000 A ~ 1200 A, and the cooling rate is controlled to be 3 mm / min ~ 5 mm / min to obtain the electroslag ingot of a predetermined diameter.

4. The method according to claim 2, characterized in that: The method further comprises: in step S10, adding a grain refiner during the electroslag remelting stage, wherein the weight percentage of the grain refiner relative to the alloy raw material is 0.01% to 0.05%.

5. The method according to claim 2, characterized in that: Step S20 specifically includes: performing homogenization treatment on the electroslag ingot at 1200° C. to 1250° C. and keeping the temperature for 2 h to 4 h.

6. The method according to claim 2, characterized in that Step S30 specifically includes: S31 before starting forging: keeping the electroslag ingot at 1150 ℃ ~ 1200 ℃ for 2h ~ 3h; S32. First forging: The first forging is carried out at a forging temperature of 1150℃~1200℃, and the deformation is controlled to be 20%~30%; S33. Second forging: The second forging is carried out at a forging temperature of 1050℃~1150℃, and the deformation is controlled to be 10%~20%. Multi-directional forging should be adopted during the forging process; S34. Final forging: Final forging is performed at a final forging temperature of 950°C to 1050°C, the deformation is controlled to be 10% to 20%, and air cooling is performed after forging; and S35. Repeat step S33 until the electroslag ingot is cut into the square billet of a predetermined size.

7. The method according to claim 2, characterized in that In step S40, the hot rolling process parameters include initial rolling temperature, final rolling temperature, deformation amount and rolling speed, and in step S40, the initial rolling temperature is controlled to be 1100℃~1150℃, the final rolling temperature is 850℃~900℃, the deformation amount is 40%-80%, and the rolling speed is 1m / min~3m / min.

8. The method according to claim 7, characterized in that The step S40 specifically includes: S41. The billet is heated to the initial rolling temperature for the first hot rolling, and the deformation of the first hot rolling is controlled at 30% to 50% to obtain a bar after initial rolling; S42. The bar after the initial rolling is heated again to the initial rolling temperature for secondary hot rolling, the deformation of the secondary hot rolling is controlled at 10% to 30%, and the temperature is controlled to be the final rolling temperature of the bar; and S43. Repeat step S42 until a hot-rolled rod with a predetermined diameter is obtained.

9. The method according to claim 2, characterized in that Step S50 specifically includes: performing directional and zoned cooling on the hot-rolled rod through a variable frequency cooling water zero-spray system, spraying at a speed of 5 cm / s to 15 cm / s in the horizontal direction and 20 cm / s to 50 cm / s in the vertical direction.

10. The method according to claim 2, characterized in that Step S60 specifically includes: Solution treatment: keep the hot rolled bars after hot rolling at 1080℃~1150℃ for 1h~4h; Aging treatment: First, the hot-rolled bars after solution treatment are aged at 900℃~1000℃ for the first stage, and kept warm for 2h~3h; then the temperature is raised to 700℃~800℃ for the second stage, and kept warm for 4h~6h.

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