A GH4065A alloy hot-rolled bar and its preparation method

Abstract

This application relates to the field of high-temperature alloy technology, specifically disclosing a GH4065A alloy hot-rolled bar and its preparation method. The preparation method of the GH4065A alloy hot-rolled bar of this application includes the following steps: smelting, forging, hot rolling, and heat treatment; hot rolling: heating the forged bar to 1000-1150°C, then holding it at this temperature, with the holding time set according to the alloy thickness and calculated based on 1-1.5 mm / min; then hot rolling, with the initial rolling temperature at 1000-1150°C and the final rolling temperature at 900-1100°C; hot rolling for 5-8 passes, with a deformation of 20-50% per pass. The preparation method of this application can produce small-sized GH4065A alloy hot-rolled bars with a diameter of 12-45 mm. The GH4065A alloy hot-rolled bars have good tensile properties, endurance properties, fatigue resistance, and creep properties under conditions of room temperature to 750°C.

Description

Technical Field

[0001] The present application relates to the technical field of high-temperature alloys, and in particular to a GH4065A alloy hot-rolled bar and a preparation method thereof. Background Art

[0002] GH4065A is a new, difficult-to-deform nickel-based superalloy with a service temperature of up to 750°C. It exhibits excellent high-temperature strength, fatigue resistance, creep performance, corrosion and oxidation resistance, and long-term high-temperature structural stability. Therefore, GH4065A is considered a key material for key hot-end components in the next generation of high-performance aircraft engines. It meets the high performance, stability, and reliability requirements of aircraft engines and is a key material for future development.

[0003] However, due to the high degree of alloying of GH4065A alloy and the γ′ phase content as high as 42%, the alloy has high deformation resistance and poor thermoplasticity. When using it to prepare small-sized alloy bars with a diameter of 12-45mm, problems such as cracking, bending, and sensitivity of microstructure and properties to hot processing parameters are easily caused during forging and hot rolling.

[0004] Therefore, it is necessary to develop a preparation method of GH4065A alloy hot-rolled bars to obtain small-sized GH4065A alloy hot-rolled bars with excellent mechanical properties. Summary of the Invention

[0005] In order to obtain a small-sized GH4065A alloy hot-rolled bar with excellent mechanical properties, the present application provides a GH4065A alloy hot-rolled bar and a preparation method thereof.

[0006] In a first aspect, the present application provides a method for preparing a GH4065A alloy hot-rolled bar, which adopts the following technical solution:

[0007] A method for preparing a GH4065A alloy hot-rolled bar comprises the following steps: smelting, forging, hot rolling and heat treatment;

[0008] Hot rolling: The forged bar is heated to 1000℃~1150℃, then kept at the above temperature. The holding time is set according to the alloy thickness and calculated based on 1~1.5mm / min. Then hot rolling is carried out, with the starting rolling temperature at 1000℃~1150℃ and the finishing rolling temperature at 900℃~1100℃.

[0009] Hot rolling is performed 5 to 8 times, with the deformation of each time being 20% ​​to 50%.

[0010] This application uses smelting, forging, hot rolling, and heat treatment steps to produce a GH4065A alloy hot-rolled bar. By adjusting the hot rolling process parameters within the aforementioned range, the bar is prevented from cracking and bending during the hot rolling process, the hot rolling yield is improved, and a small-sized GH4065A alloy hot-rolled bar is obtained. The GH4065A alloy hot-rolled bar obtained by this preparation method exhibits excellent tensile properties, endurance, fatigue resistance, and creep performance at temperatures between room temperature and 750°C.

[0011] In the rolling step of the present application, the term "deformation per fire" refers to the change in the cross-sectional area of ​​the bar, and the calculation formula is: deformation per fire (%) = (cross-sectional area of ​​the bar before rolling - cross-sectional area of ​​the bar after rolling) / cross-sectional area of ​​the bar before rolling. In a specific embodiment, the rolling fires can be 5, 6 or 7 times.

[0012] Preferably, the mass percentages of the components in the GH4065A alloy hot-rolled bar are: C: 0.005-0.020%, Cr: 15.5-16.5%, Co: 12.5-13.5%, W: 3.8-4.2%, Mo: 3.8-4.2%, Al: 1.90-2.40%, Ti: 3.55-3.90%, Nb: 0.6-0.9%, Zr: 0.03-0.06%, B: 0.012-0.020%, Mg < 0.005%, N ≤ 35 ppm, O ≤ 50 ppm, S ≤ 10 ppm, Fe ≤ 1.2%, and the balance is Ni.

[0013] Preferably, the smelting step includes vacuum induction melting, electroslag remelting and vacuum consumable remelting; the casting temperature of the vacuum induction melting is 1400℃~1500℃; the melting speed of the electroslag remelting is 3.5~5.5kg / min; the melting speed of the vacuum consumable remelting is 3.0~4.0kg / min, and the diameter of the ingot obtained by vacuum consumable remelting is 500mm~600mm.

[0014] The smelting step of the present application adopts a triple smelting process of "vacuum induction melting + electroslag remelting + vacuum consumable melting". The above triple smelting can produce high-quality, low-segregation, and metallurgical defect-free consumable remelting ingots.

[0015] Preferably, the forging step adopts an upsetting forging method, the number of upsetting forging is ≥3 times, and the upsetting height-to-diameter ratio is ≤3.

[0016] Preferably, the forging temperature is 1000°C to 1150°C; the initial forging temperature is 1000°C to 1150°C, the final forging temperature is 900°C to 1100°C, and the diameter of the fine-grained rod obtained by forging is 100-150 mm.

[0017] Preferably, the hot-rolled bar is further required to be annealed and straightened before the heat treatment step, and the straightness of the bar after straightening is less than 5 mm / m.

[0018] Preferably, the heat treatment includes solution treatment and aging treatment. The solution treatment temperature is 1050° C. to 1100° C. and the time is 1-8 hours. The aging treatment temperature is 700° C. to 850° C. and the time is 6-24 hours.

[0019] In a second aspect, the present application provides a GH4065A alloy hot-rolled bar produced by a method for producing a GH4065A alloy hot-rolled bar.

[0020] Preferably, the diameter of the GH4065A alloy hot-rolled bar is 12 to 45 mm.

[0021] In summary, this application has the following beneficial effects:

[0022] The present application provides a method for preparing a GH4065A alloy hot-rolled bar, which comprises the steps of smelting (vacuum induction + electroslag remelting + vacuum consumable), forging, hot rolling and heat treatment. By adjusting the process parameters of the hot rolling step, the present application can avoid problems such as cracking, bending, and sensitivity of microstructure and properties to hot working parameters during hot rolling of the bar, thereby obtaining a small-sized GH4065A alloy hot-rolled bar with a diameter of 12 mm to 45 mm. The GH4065A alloy hot-rolled bar has good tensile properties, endurance properties, fatigue resistance and creep properties under conditions of room temperature to 750°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the OM structure diagram of the GH4065A alloy hot-rolled bar provided by the present application (a is forged state, b is heat-treated state);

[0024] Figure 2 This is a γ′ phase morphology diagram of the GH4065A alloy hot-rolled bar provided in the present application (a is ×5000 times, b is ×50000 times). DETAILED DESCRIPTION

[0025] The present application provides a method for preparing a GH4065A alloy hot-rolled bar, which specifically comprises the following steps:

[0026] (1) Melting:

[0027] (1-1) Vacuum induction melting

[0028] The raw materials are prepared according to the following chemical composition contents, and are cast at a high temperature of 1400°C to 1500°C to form electrode rods;

[0029] The chemical composition of GH4065A alloy is as follows: C: 0.005-0.020%, Cr: 15.5-16.5%, Co: 12.5-13.5%, W: 3.8-4.2%, Mo: 3.8-4.2%, Al: 1.90-2.40%, Ti: 3.55-3.90%, Nb: 0.6-0.9%, Zr: 0.03-0.06%, B: 0.012-0.020%, Mg < 0.005%, N: ≤ 35ppm, O ≤ 50ppm, S ≤ 10ppm, Fe ≤ 1.2, and the balance is Ni.

[0030] (1-2) Electroslag remelting: The electrode rod cast in step (1) is remelted in an electroslag remelting continuous directional solidification crystallizer to prepare an ingot; wherein the electroslag remelting melting rate is 3.5 to 5.5 kg / min; the slag system used is a CaF2-Al2O3-CaO-TiO2-ZrO2 five-element slag system.

[0031] (1-3) Vacuum consumable remelting: First, dust and other pollutants adhering to the surface of the electrode during transfer and storage are removed; then, the ingot obtained in step (1-2) is vacuum consumable remelted and cooled to obtain an ingot with a diameter of 500 mm to 600 mm; wherein, the melting rate of the vacuum consumable remelting is 3.0 to 4.0 kg / min, and the total cooling time is 60 min to 120 min.

[0032] (2) Forging: The ingot obtained in step (1) is placed on a fast forging machine and subjected to upsetting forging for not less than 3 times, and then fine forging is performed on a radial forging machine to obtain a fine-grained bar with a diameter of 100-150 mm; the forging temperature is 1000°C-1150°C; the initial forging temperature is 1000°C-1150°C, and the final forging temperature is 900°C-1100°C.

[0033] (3) Hot rolling: The forged bar is heated to 1000℃~1150℃, and then kept at the above temperature. The holding time is set according to the alloy thickness and calculated based on 1~1.5mm / min. Then hot rolling is carried out, with the starting rolling temperature at 1000℃~1150℃ and the finishing rolling temperature at 900℃~1100℃.

[0034] Hot rolling is performed 5 to 8 times, with the deformation of each time being 20% ​​to 50%.

[0035] (4) Straightening: The hot-rolled bars are annealed and then straightened. The straightness of the bars after straightening is less than 5 mm / m.

[0036] (5) Heat treatment: The hot-rolled and straightened bars are subjected to solution treatment and aging treatment to obtain GH4065A alloy hot-rolled bars. The solution treatment temperature is 1050°C to 1100°C for 1-8 hours, and the aging treatment temperature is 700°C to 850°C for 6-24 hours.

[0037] The raw materials and the like used in this application can be obtained commercially.

[0038] The present application is further described in detail below in conjunction with preparation examples, embodiments, performance testing experiments and accompanying drawings.

[0039] Preparation Example 1

[0040] Preparation Example 1 provides a GH4065A alloy ingot.

[0041] The preparation method of the above-mentioned GH4065A alloy ingot is as follows:

[0042] (1-1) Vacuum induction melting technology: The raw materials are prepared according to the following chemical composition contents in percentage by mass, and are cast at a high temperature of 1400°C to 1500°C to form electrode rods;

[0043] The chemical composition of GH4065A alloy is as follows: C: 0.006%, Cr: 15.8%, Co: 12.9%, W: 3.9%, Mo: 4.0%, Al: 2.0%, Ti: 3.7%, Nb: 0.7%, Zr: 0.04%, B: 0.016%, Mg 0.003%, N: 30ppm, O: 50ppm, S: 10ppm, Fe 0.5%, and the balance is Ni.

[0044] (1-2) Electroslag remelting: The electrode rod cast in step (1) is remelted in an electroslag remelting continuous directional solidification crystallizer to prepare an ingot; wherein the electroslag remelting melting rate is 4.0 kg / min; the slag system used is a CaF2-Al2O3-CaO-TiO2-ZrO2 five-element slag system.

[0045] (1-3) Vacuum consumable remelting: First, dust and other contaminants adhering to the surface of the electrode during transfer and storage are removed; then, the ingot obtained in step (1-2) is vacuum consumable remelted and cooled to obtain an ingot with a diameter of 508 mm; wherein, the vacuum consumable remelting melting rate is 3.5 kg / min, and the total cooling time is 120 min.

[0046] The composition of the GH4065A alloy ingot obtained in Preparation Example 1 was tested, and the results are shown in Table 1.

[0047] Table 1 Composition and content of the ingot provided by Preparation Example 1

[0048] element Co Cr Mo W Al Ti Nb Zr content(%) 12.80 15.7 4.0 3.9 2.1 3.6 0.70 0.05 element B C Mg Fe N S O Ni content(%) 0.015 0.007 0.0008 0.5 10ppm 4ppm 33ppm margin

[0049] Example 1

[0050] Example 1 provides a method for preparing a GH4065A alloy hot-rolled bar, comprising the following steps:

[0051] (1) Melting: Melting was performed according to the method of Preparation Example 1 to obtain a GH4065A alloy ingot with a diameter of 508 mm.

[0052] (2) Forging: First, the GH4065A alloy ingot is subjected to a multi-stage homogenization treatment to eliminate low-melting-point phases and reduce the degree of dendritic segregation. The ingot is then repeatedly uprooted and drawn using a conventional high-speed forging machine, and then fine-forged on a radial forging machine to obtain a fine-grained bar with a diameter of 130 mm. The initial forging temperature is 1089°C, and the final forging temperature is 955°C.

[0053] (3) Hot rolling: The fine-grained bar with a diameter of 130 mm obtained by forging is subjected to 6 hot rolling. The specific steps are as follows:

[0054] First fire: the forged bar (cross-sectional area of ​​65 2 πmm 2 ) was heated to 1080°C and then kept at the above temperature for 130 min; then hot rolled to obtain a bar with a diameter of 110 mm (cross-sectional area of ​​55 2 πmm 2 ), the deformation is 28.4%. The initial rolling temperature is 1060℃ and the final rolling temperature is 948℃;

[0055] Second fire: The bar obtained in the first fire (cross-sectional area of ​​55 2 πmm 2 ) was heated to 1080°C and then kept at the above temperature for 110 min; then hot rolled to obtain a bar with a diameter of 90 mm (cross-sectional area of ​​45 2 πmm 2 ), the deformation is 33.1%. The initial rolling temperature is 1055℃, and the final rolling temperature is 953℃;

[0056] The third fire: the bar obtained in the second fire (cross-sectional area of ​​45 2 πmm 2 ) was heated to 1080°C and then kept at the above temperature for 90 min; then hot rolled to obtain a bar with a diameter of 48 mm (cross-sectional area of ​​24 2 πmm 2 ), the deformation amount is 36.0%. The initial rolling temperature is 1047℃, and the final rolling temperature is 947℃;

[0057] 4th fire: The bar obtained from the 3rd fire (cross-sectional area of ​​242 πmm 2 ) was heated to 1080°C and then kept at the above temperature for 90 min; then hot rolled to obtain a bar with a diameter of 36 mm (cross-sectional area of ​​18 2 πmm 2 ), the deformation is 43.7%. The initial rolling temperature is 1056℃, and the final rolling temperature is 944℃;

[0058] 5th fire: The bars obtained in the 4th fire (cross-sectional area of ​​18 2 πmm 2 ) was heated to 1080°C and then kept at the above temperature for 36 min; then hot rolled to obtain a bar with a diameter of 30 mm (cross-sectional area of ​​15 2 πmm 2 ), the deformation is 30.5%. The initial rolling temperature is 1052℃, and the final rolling temperature is 942℃;

[0059] 6th fire: The bar obtained from the 5th fire (cross-sectional area of ​​15 2 πmm 2 ) was heated to 1080°C and then kept at the above temperature for 30 min; then hot rolled to obtain a bar with a diameter of 26 mm (cross-sectional area of ​​13 2 πmm 2 ), the deformation amount is 24.8%. The initial rolling temperature is 1048℃ and the final rolling temperature is 933℃.

[0060] (4) Straightening: The hot-rolled bars are annealed and then straightened. The straightness of the bars after straightening is less than 5 mm / m.

[0061] (5) Heat treatment: The hot-rolled bars were solution treated at 1080 °C for 2 h, then aged at 760 °C for 8 h, and air-cooled to obtain GH4065A alloy hot-rolled bars.

[0062] The typical microstructure of the GH4065A alloy hot-rolled bar obtained in Example 1 is as follows: Figure 1 and Figure 2 As shown by Figure 1 It can be seen that the grain size of the alloy rod is level 10; Figure 2 It can be seen that there are three scales of γ′ phase in the alloy. Large-sized primary γ′ phase with a diameter of about 0.5μm to 2μm is distributed at the grain boundaries, secondary γ′ phase with a diameter of about 30nm to 150nm is dispersed inside the grains, and small-sized tertiary γ′ phase with a spherical diameter of about 10nm to 50nm precipitated at the grain boundaries.

[0063] Example 2

[0064] Example 2 provides a method for preparing GH4065A alloy hot-rolled bars.

[0065] The difference between the above embodiment 2 and embodiment 1 lies in forging and hot rolling, as follows:

[0066] (2) Forging: First, the GH4065A alloy ingot is subjected to a multi-stage homogenization treatment to eliminate low-melting-point phases and reduce the degree of dendritic segregation. The ingot is then repeatedly uprooted and drawn using a conventional high-speed forging machine, and then fine-forged on a radial forging machine to obtain a fine-grained bar with a diameter of 140 mm. The initial forging temperature is 1080°C, and the final forging temperature is 977°C.

[0067] (3) Hot rolling: The fine-grained bar with a diameter of 140 mm obtained by forging is subjected to five hot rolling steps. The specific steps are as follows:

[0068] First fire: the forged bar (cross-sectional area of ​​70 2 πmm 2 ) was heated to 1100°C and then kept at the above temperature for 140 min; then hot rolled to obtain a bar with a diameter of 100 mm (cross-sectional area of ​​50 2 πmm 2 ), the deformation amount is 49.0%. The initial rolling temperature is 1066℃, and the final rolling temperature is 941℃;

[0069] Second fire: The bars obtained in the first fire (cross-sectional area of ​​50 2 πmm 2 ) was heated to 1100°C and then kept at the above temperature for 100 min; then hot rolled to obtain a bar with a diameter of 76 mm (cross-sectional area of ​​38 2 πmm 2 ), the deformation is 42.2%. The initial rolling temperature is 1057℃, and the final rolling temperature is 942℃;

[0070] The third fire: the bar obtained in the second fire (cross-sectional area of ​​38 2 πmm 2 ) was heated to 1100°C and then kept at the above temperature for 76 min; then hot rolled to obtain a bar with a diameter of 56 mm (cross-sectional area of ​​28 2 πmm 2 ), the deformation is 45.7%. The initial rolling temperature is 1062℃, and the final rolling temperature is 948℃;

[0071] The fourth fire: the bar obtained in the third fire (cross-sectional area of ​​28 2 πmm 2 ) was heated to 1100°C and then kept at the above temperature for 56 min; then hot rolled to obtain a bar with a diameter of 40 mm (cross-sectional area of ​​20 2 πmm 2), the deformation amount is 49.0%. The initial rolling temperature is 1054℃, and the final rolling temperature is 934℃;

[0072] 5th fire: The bars obtained in the 4th fire (cross-sectional area of ​​20 2 πmm 2 ) was heated to 1100°C and then kept at the above temperature for 40 min; then hot rolled to obtain a bar with a diameter of 30 mm (cross-sectional area of ​​15 2 πmm 2 The initial rolling temperature is 1059℃ and the final rolling temperature is 927℃.

[0073] Example 3

[0074] Example 3 provides a method for preparing GH4065A alloy hot-rolled bars.

[0075] The difference between the above embodiment 3 and embodiment 1 is that the hot rolling is as follows:

[0076] (2) Forging: First, the GH4065A alloy ingot is subjected to a multi-stage homogenization treatment to eliminate low-melting-point phases and reduce the degree of dendritic segregation. The ingot is then repeatedly uprooted and drawn using a conventional high-speed forging machine, and then fine-forged on a radial forging machine to obtain a fine-grained bar with a diameter of 150 mm. The initial forging temperature is 1075°C, and the final forging temperature is 946°C.

[0077] (3) Hot rolling: The fine-grained bar with a diameter of 150 mm obtained by forging is subjected to 7 hot rolling. The specific steps are as follows:

[0078] First fire: the forged bar (cross-sectional area of ​​75 2 πmm 2 ) was heated to 1080°C and then kept at the above temperature for 150 min; then hot rolled to obtain a bar with a diameter of 108 mm (cross-sectional area of ​​54 2 πmm 2 ), the deformation is 48.1%. The initial rolling temperature is 1053℃, and the final rolling temperature is 943℃;

[0079] Second fire: The bars obtained in the first fire (cross-sectional area of ​​54 2 πmm 2 ) was heated to 1080°C and then kept at the above temperature for 108 min; then hot rolled to obtain a bar with a diameter of 80 mm (cross-sectional area of ​​40 2 πmm 2 ), the deformation is 45.1%. The initial rolling temperature is 1057℃, and the final rolling temperature is 936℃;

[0080] The third fire: the bar obtained in the second fire (cross-sectional area of ​​402 πmm 2 ) was heated to 1080°C and then kept at the above temperature for 80 min; then hot rolled to obtain a bar with a diameter of 60 mm (cross-sectional area of ​​30 2 πmm 2 ), the deformation is 43.8%. The initial rolling temperature is 1053℃, and the final rolling temperature is 947℃;

[0081] 4th fire: The bar obtained from the 3rd fire (cross-sectional area of ​​30 2 πmm 2 ) was heated to 1080°C and then kept at the above temperature for 60 min; then hot rolled to obtain a bar with a diameter of 44 mm (cross-sectional area of ​​22 2 πmm 2 ), the deformation is 46.2%. The initial rolling temperature is 1061℃, and the final rolling temperature is 934℃;

[0082] 5th fire: The bar obtained from the 4th fire (cross-sectional area of ​​22 2 πmm 2 ) was heated to 1080°C and then kept at the above temperature for 44 min; then hot rolled to obtain a bar with a diameter of 32 mm (cross-sectional area of ​​16 2 πmm 2 ), the deformation is 47.1%. The initial rolling temperature is 1051℃, and the final rolling temperature is 940℃;

[0083] 6th fire: The bar obtained from the 5th fire (cross-sectional area of ​​16 2 πmm 2 ) was heated to 1080°C and then kept at the above temperature for 32 minutes; then hot rolled to obtain a bar with a diameter of 26 mm (cross-sectional area of ​​13 2 πmm 2 ), the deformation amount is 34.0%. The initial rolling temperature is 1062℃, and the final rolling temperature is 942℃;

[0084] 7th fire: The bar obtained from the 6th fire (cross-sectional area of ​​13 2 πmm 2 ) was heated to 1080°C and then kept at the above temperature for 26 minutes; then hot rolled to obtain a bar with a diameter of 20 mm (cross-sectional area of ​​10 2 πmm 2 ), the deformation amount is 40.8%. The initial rolling temperature is 1054℃ and the final rolling temperature is 938℃.

[0085] Comparative Example 1

[0086] Comparative Example 1 provides a method for preparing a GH4065A alloy hot-rolled bar.

[0087] The difference between the comparative example and Example 1 is that the forging and hot rolling are as follows:

[0088] (2) Forging: First, the GH4065A alloy ingot is subjected to a multi-stage homogenization treatment to eliminate low-melting-point phases and reduce the degree of dendritic segregation. The ingot is then repeatedly uprooted and drawn using a conventional high-speed forging machine, and then fine-forged on a radial forging machine to obtain a fine-grained bar with a diameter of 130 mm. The initial forging temperature is 1039°C, and the final forging temperature is 938°C.

[0089] (3) Hot rolling: The fine-grained bar with a diameter of 130 mm obtained by forging is subjected to four hot rolling steps. The specific steps are as follows:

[0090] First fire: the forged bar (cross-sectional area of ​​65 2 πmm 2 ) was heated to 1080°C and then kept at the above temperature for 130 min; then hot rolled to obtain a bar with a diameter of 90 mm (cross-sectional area of ​​45 2 πmm 2 ), the deformation is 52.1%. The initial rolling temperature is 1061℃, and the final rolling temperature is 970℃;

[0091] Second fire: The bars obtained in the first fire (with a cross-sectional area of ​​45 2 πmm 2 ) was heated to 1080°C and then kept at the above temperature for 90 min; then hot rolled to obtain a bar with a diameter of 60 mm (cross-sectional area of ​​30 2 πmm 2 ), the deformation is 55.6%. The initial rolling temperature is 1065℃, and the final rolling temperature is 967℃;

[0092] The third fire: the bar obtained in the second fire (cross-sectional area of ​​30 2 πmm 2 ) was heated to 1080°C and then kept at the above temperature for 60 min; then hot rolled to obtain a rod with a diameter of 40 mm (cross-sectional area of ​​20 2 πmm 2 ), the deformation is 55.6%. The initial rolling temperature is 1062℃, and the final rolling temperature is 960℃;

[0093] The fourth fire: the bar obtained in the third fire (cross-sectional area of ​​20 2 πmm 2 ) was heated to 1080°C and then kept at the above temperature for 40 min; then hot rolled to obtain a bar with a diameter of 26 mm (cross-sectional area of ​​13 2 πmm 2), the deformation is 57.7%. The initial rolling temperature is 1059℃, and the final rolling temperature is 959℃;

[0094] Performance Testing The mechanical properties of the GH4065A alloy hot-rolled bars obtained in Examples 1-3 and Comparative Example 1 were tested, and the results are shown in Table 2 below.

[0095] The testing methods for various mechanical properties are as follows:

[0096] (1) According to ASTM E 21 standard, the tensile properties of the bars at room temperature and 400℃ are tested, including the tensile strength σ b , yield strength σ 0.2 , sample elongation δ5, and section shrinkage ψ.

[0097] (2) According to ASTM E 21 standard, the tensile properties of the bar at 650℃, including the tensile strength σ b , yield strength σ 0.2 , sample elongation δ5, and section shrinkage ψ.

[0098] (3) According to ASTM E 139 standard, the endurance performance of the bar at 650℃ and normal stress σ of 950MPa was tested, including the fracture time τ and the specimen elongation δ5.

[0099] (5) According to ASTM E139 standard, the plastic strain εp of the bar is tested at 700℃, normal stress σ is 690MPa, and 100h.

[0100] (6) The 650℃ low cycle fatigue performance test should be carried out in accordance with ASTM E 606.

[0101] Table 2 Mechanical properties test results of GH4065A alloy hot-rolled bars of Examples 1-3 and Comparative Example 1

[0102]

[0103]

[0104] The room temperature tensile test results show that the room temperature tensile strength σ of the GH4065A alloy hot-rolled bars prepared in Examples 1-3 of the present application is b is 1595-1624MPa, and the room temperature yield strength σ 0.2 is 1247-1261MPa, the elongation δ5 at room temperature is 28.4-29.7%, and the cross-sectional shrinkage ψ at room temperature is 42-45%; while the room temperature tensile strength σ of the GH4065A alloy hot-rolled bar prepared in Comparative Example 1 is b is 1537MPa, and the room temperature yield strength σ 0.2The tensile strength, yield strength, elongation and shrinkage of the GH4065A alloy hot-rolled bars obtained in Examples 1-3 and Comparative Example 1 are 1245 MPa, the elongation δ5 at room temperature is 28.2%, and the cross-sectional shrinkage ψ at room temperature is 40%.

[0105] The results of the 400°C tensile test show that the 400°C tensile strength σ of the GH4065A alloy hot-rolled bars prepared in Examples 1-3 of the present application is b 1537-1564MPa, 400℃ yield strength σ 0.2 The tensile strength of the GH4065A alloy hot-rolled bar prepared in Comparative Example 1 at 400°C is σ b 1510MPa, 400℃ yield strength σ 0.2 It is 1120 MPa, the elongation δ5 at 400°C is 21.23%, and the cross-sectional reduction rate ψ at 400°C is 21.9%. Obviously, the GH4065A alloy hot-rolled bar obtained in Comparative Example 1 has low tensile strength and yield strength at a high temperature of 400°C, and the elongation and shrinkage are slightly worse.

[0106] The 650℃ tensile test results show that the 650℃ tensile strength σ of the GH4065A alloy hot-rolled bars prepared in Examples 1-3 of the present application is b 1429-1451MPa, 650℃ yield strength σ 0.2 The tensile strength of the GH4065A alloy hot-rolled bar at 650°C is 1187-1217MPa, the elongation δ5 at 650°C is 23.5-25.5%, and the cross-sectional shrinkage ψ at 650°C is 20.4-22.2%. b 850MPa, 650℃ yield strength σ 0.2 It is 723 MPa, the elongation δ5 at 650°C is 9.81%, and the cross-sectional reduction rate ψ at 650°C is 2.47%. Obviously, the GH4065A alloy hot-rolled bar obtained in Comparative Example 1 has low tensile strength and yield strength at a high temperature of 650°C, and poor elongation and shrinkage.

[0107] The results of the 650°C endurance test show that the GH4065A alloy hot-rolled bars obtained in Examples 1-3 of the present application have a fracture time of 81.33-83.3 h and an elongation δ5 of 5.2-5.3% at 650°C and a normal stress σ of 950 MPa; while the GH4065A alloy hot-rolled bar obtained in Comparative Example 1 has a fracture time of 56.66 h and an elongation δ5 of 4.0% at 650°C and a normal stress σ of 950 MPa; obviously, the endurance of the GH4065A alloy hot-rolled bar obtained in Comparative Example 1 at a high temperature of 650°C is poor.

[0108] The creep test results at 700°C show that the plastic strain εp of the GH4065A alloy hot-rolled bars prepared in Examples 1-3 of the present application at 700°C, a normal stress σ of 690 MPa, and 100 h is 0.116-0.118; while the plastic strain εp of the GH4065A alloy hot-rolled bar prepared in Comparative Example 1 at 700°C, a normal stress σ of 690 MPa, and 100 h is 0.194. Obviously, the creep property of the GH4065A alloy hot-rolled bar obtained in Comparative Example 1 is poor at a high temperature of 650°C.

[0109] From the results of the 650°C low-cycle fatigue test, it can be seen that the number of cycles of the GH4065A alloy hot-rolled bars prepared in Examples 1-3 of the present application can reach more than 20,000 times, while the number of cycles of the GH4065A alloy hot-rolled bar prepared in Comparative Example 1 is only 17,247 times, indicating that the fatigue resistance of the GH4065A alloy hot-rolled bar obtained in Comparative Example 1 at 650°C is poor.

[0110] In summary, the preparation method of the GH4065A alloy hot-rolled bar provided in this application can produce GH4065A alloy hot-rolled bar with a diameter of 12-45 mm, and the GH4065A alloy hot-rolled bar has excellent comprehensive mechanical properties at room temperature to 750°C.

[0111] While the present invention has been described in detail above using general descriptions and specific embodiments, it will be apparent to those skilled in the art that modifications and improvements may be made based on the present invention. Therefore, such modifications and improvements, without departing from the spirit of the present invention, are intended to be within the scope of protection claimed herein.

Claims

1. A method for preparing GH4065A alloy hot-rolled bars, characterized in that: The specific steps include: Melting, forging, hot rolling and heat treatment; Hot rolling: The forged bar is heated to 1000℃~1150℃, then held at the above temperature. The holding time is set according to the alloy thickness and calculated based on 1~1.5mm / min. Then hot rolling is carried out, with the starting rolling temperature at 1000℃~1150℃ and the finishing rolling temperature at 900℃~1100℃. Hot rolling 5~7 times, with deformation of 20%~50% per time; The diameter of the GH4065A alloy hot-rolled bar is 12-45 mm.

2. The method for preparing a GH4065A alloy hot-rolled bar according to claim 1, characterized in that: The mass percentages of the components in the GH4065A alloy hot-rolled bar are: C: 0.005-0.020%, Cr: 15.5-16.5%, Co: 12.5-13.5%, W: 3.8-4.2%, Mo: 3.8-4.2%, Al: 1.90-2.40%, Ti: 3.55-3.90%, Nb: 0.6-0.9%, Zr: 0.03-0.06%, B: 0.012-0.020%, Mg < 0.005%, N ≤ 35 ppm, O ≤ 50 ppm, S ≤ 10 ppm, Fe ≤ 1.2%, and the balance is Ni.

3. The method for preparing a GH4065A alloy hot-rolled bar according to claim 1, characterized in that: The smelting steps include vacuum induction melting, electroslag remelting and vacuum consumable remelting; The casting temperature of the vacuum induction melting is 1400°C to 1500°C; The electroslag remelting speed is 3.5-5.5 kg / min; The melting speed of the vacuum consumable remelting is 3.0-4.0 kg / min, and the diameter of the ingot obtained by the vacuum consumable remelting is 500 mm-600 mm.

4. The method for preparing the GH4065A alloy hot-rolled bar according to claim 1, wherein: The forging step adopts an upsetting forging method, the number of upsetting forging is ≥3 times, and the upsetting and pressing height-to-diameter ratio is ≤3.

5. The method for preparing the GH4065A alloy hot-rolled bar according to claim 1, characterized in that: The forging temperature is 1000°C to 1150°C; the initial forging temperature is 1000°C to 1150°C, the final forging temperature is 900°C to 1100°C, and the diameter of the fine-grained rod obtained by forging is 100-150mm.

6. The method for preparing the GH4065A alloy hot-rolled bar according to claim 1, characterized in that: Before the heat treatment step, the hot-rolled bar needs to be annealed and straightened; the straightness of the bar after straightening is less than 5 mm / m.

7. The method for preparing the GH4065A alloy hot-rolled bar according to any one of claims 1 to 6, characterized in that: The heat treatment includes solution treatment and aging treatment. The solution treatment temperature is 1050° C. to 1100° C. and the time is 1-8 hours. The aging treatment temperature is 700° C. to 850° C. and the time is 6-24 hours.

8. A GH4065A alloy hot-rolled bar, characterized in that: The hot-rolled GH4065A alloy bar is prepared by the preparation method of any one of claims 1 to 7.

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