A method for producing a nickel-based wrought superalloy strip having increased single-volum weight

Abstract

The application belongs to the technical field of high-temperature alloy strip preparation for aerospace, and particularly relates to a preparation method of nickel-based wrought high-temperature alloy strip capable of increasing single roll weight. The method comprises the following steps: first, vacuum electron beam welding is performed on a nickel-based wrought high-temperature alloy blank plate; before welding, the base material is chemically cleaned, paired and clamped; vacuum is drawn; sectional electron beam welding is performed; the vacuum chamber is cooled; and the vacuum electron beam welding process is optimized to obtain an excellent weld with good forming, no pores and no cracks; then, through intermediate rolling process deformation and annealing system selection, the recrystallization grain size of the nickel-based wrought high-temperature alloy strip and the welded joint is effectively controlled. The nickel-based wrought high-temperature alloy strip prepared by the method has high single roll weight, good mechanical properties, and the welded joint and the base material achieve equal strength matching; the room temperature mechanical properties of the nickel-based wrought high-temperature alloy strip and the welded joint meet the following requirements: the yield strength Rp0.2 is not less than 370 MPa, the tensile strength Rm is not less than 780 MPa, and the room temperature elongation A is not less than 25%.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature alloy strip preparation technology for aerospace applications, specifically relating to a method for preparing nickel-based wrought high-temperature alloy strips that can increase the weight of a single roll. Background Technology

[0002] GH3536 is a nickel-based wrought superalloy with a high Fe content, primarily strengthened by Cr and Mo solid solution. It possesses excellent oxidation and corrosion resistance, exhibits moderate creep and hardness below 900℃, and demonstrates good cold and hot workability and weldability. Its strip can be used to manufacture complex thin-walled structural components such as aero-engine combustion bushings, turbine exhaust components, and aircraft cabin heaters, playing a decisive role in structural weight reduction and improving engine performance, and accounting for a significant proportion of applications. Special Metals Corporation (SMC) in the United States has achieved coil rolling of superalloy strips, with single coils weighing over 10 tons. These coils exhibit stable performance, a good balance of strength and toughness, and excellent stamping plasticity, representing the highest level and development direction of special metal profiles.

[0003] To achieve the preparation of high-single-coil weight high-temperature alloys, the sheet blanks used for preparing the strip need to be welded together before rolling. To ensure the quality of the welded joints and to match the mechanical properties of the welded joints with the base strip after rolling, precise control of the welding process is necessary. Due to the thinness of the strip, welding is difficult, and ordinary welding methods (such as TIG and MIG) result in high heat input and severe welding deformation, making them unsuitable for welding thin materials. Furthermore, cold-rolled GH3536 has high strength (yield strength can reach over 1500 MPa) but poor plasticity (elongation generally does not exceed 5%), requiring subsequent annealing treatment to obtain stable strength and plasticity to meet the requirements of subsequent precision stamping forming of workpieces. Summary of the Invention

[0004] To address the technical problems in the preparation of high single-coil weight high-temperature alloy strips and the control of good strength and plasticity, this invention provides a method for preparing and controlling the performance of high single-coil weight nickel-based deformable high-temperature alloy strips. The GH3536 alloy strip prepared by this invention has a high single-coil weight, good mechanical properties, and the welded joint achieves equal strength matching with the base material.

[0005] The technical solution of this invention is:

[0006] A method for preparing nickel-based wrought superalloy strip that can increase the weight of a single roll involves vacuum electron beam welding of nickel-based wrought superalloy billets, comprising the following steps:

[0007] (1) The edges of the blanks to be welded must be machined to ensure the smoothness and straightness of the edges, and the surface roughness of the edges is less than 0.5μm;

[0008] (2) Chemically clean the base material before welding, and dry it after cleaning;

[0009] (3) Weld the blanks. To ensure welding quality, the gap at the weld after assembly should be ≤0.1mm.

[0010] (4) Vacuum electron beam welding is used to perform positioning welding on the weld seam in order to control the deformation of the component during the formal welding process;

[0011] (5) Vacuum electron beam welding is used to perform formal welding on the weld seam;

[0012] (6) After welding, cool in a vacuum chamber for 15 minutes;

[0013] (7) The weld area shall be inspected by X-ray. No cracks, incomplete penetration or fusion are allowed inside the entire weld.

[0014] The method for preparing nickel-based deformable high-temperature alloy strip that can increase the weight of a single roll, in step (4), the process parameters for positioning welding are as follows: voltage 60kV, welding speed 1000mm / min, focusing current 2325~2345mA, beam current 8.5~9.5mA, welding heat input 30J / mm~34J / mm, and swing amplitude in the X and Y directions 0.6mm.

[0015] In the method for preparing nickel-based deformable high-temperature alloy strip that can increase the weight of a single roll, in step (5), the formal welding adopts segmented welding, and its process parameters are as follows: for the first 70% of the weld length, the voltage is 60kV, the welding speed is 1000mm / min, the focusing current is 2325~2345mA, the beam current is 27~28mA, the welding heat input is 97J / mm~100J / mm, and the swing amplitude in the X and Y directions is 0.6mm; for the last 30% of the weld length, the voltage is 60kV, the welding speed is 1000mm / min, the focusing current is 2325~2345mA, the beam current is 26~27mA, the welding heat input is 94J / mm~97J / mm, and the swing amplitude in the X and Y directions is 0.6mm.

[0016] The method for preparing nickel-based wrought superalloy strip that can increase the weight of a single roll involves rolling the welded nickel-based wrought superalloy billet in four passes on a precision rolling mill. The deformation amount in the first two passes is 30% to 40%, and the deformation amount in the last two passes is 50% to 60%. The thickness of the rolled strip is controlled to be 0.3 to 0.5 mm, so that the nickel-based wrought superalloy strip has deformation energy storage that is conducive to recrystallization nucleation in the later stage.

[0017] The method for preparing nickel-based deformed high-temperature alloy strip that can increase the weight of a single roll involves immediately performing high-temperature intermediate flexible bright annealing after each rolling pass. The annealing temperature between rolling passes is controlled as follows: after the first three rolling passes, the annealing temperature is 1110–1150℃ and the strip speed is 10–20 m / min; after the last rolling pass, the annealing temperature is 1050–1100℃ and the strip speed is 0.5–1 m / min.

[0018] The method for preparing nickel-based deformed high-temperature alloy strip that can increase the weight of a single roll uses a continuous ammonia decomposition heat treatment furnace or a hydrogen-protected continuous heat treatment furnace as the annealing equipment.

[0019] The method for preparing nickel-based wrought superalloy strip that can increase the weight of a single roll, wherein the nickel-based wrought superalloy is GH3536 alloy, and the room temperature mechanical properties of the GH3536 alloy strip and the welded joint meet the following requirements: yield strength Rp0.2 not less than 370MPa, tensile strength Rm not less than 780MPa, room temperature elongation A not less than 25%, and the welded joint after rolling achieves equal strength matching with the base material.

[0020] The design concept of this invention is as follows:

[0021] Vacuum electron beam welding offers advantages such as high energy density, narrow weld seams and heat-affected zones, large weld depth-to-width ratio, minimal welding deformation, and easy and precise control of process parameters. It eliminates the need for welding wires or electrodes, avoiding the introduction of foreign inclusions or compositional segregation due to differences in composition. This invention utilizes a vacuum electron beam welding machine to perform segmented welding of GH3536 billet plates, followed by precision rolling to ensure the surface quality of the GH3536 alloy strip. By controlling the deformation-annealing process in intermediate passes and selecting the deformation amount and annealing regime in the final pass, the recrystallization grain size of the GH3536 alloy strip and the welded joint is effectively controlled. This ensures that the strength and ductility at the welded joint are essentially consistent with the base material, achieving the goal of preparing high-strength, high-ductility high-temperature alloy strips with high single-coil weight.

[0022] This invention employs a vacuum electron beam welding method to control the welding process parameters of the sheet metal. The rolling-annealing process of the welded sheet metal billet is optimized to obtain high-strength, high-coil-weight high-temperature alloy sheets with equal strength matching between the welded joint and the base material, and meeting the required mechanical properties. First, by precisely controlling the vacuum electron beam welding parameters in segments, a narrow, flat, and continuous weld seam is obtained, free from defects such as voids, collapses, and spatter, resulting in a weld joint strength coefficient exceeding 95%. Second, controlling the intermediate deformation and annealing process prevents problems such as cracking and strip breakage, which is a prerequisite for ensuring the final sheet metal performance. Then, the cumulative large deformation gives the GH3536 alloy strip and welded joint high deformation energy storage, establishing the relationship between the deformation-recrystallization annealing process and mechanical properties of the GH3536 strip, controlling uniform grain growth, and further ensuring the acquisition of high-strength, high-ductility high-temperature alloy strips with high coil weight.

[0023] After vacuum electron beam welding of the billet sheet, the weld joint undergoes multiple rolling and annealing processes, completely eliminating the as-cast microstructure and transforming it into a processed state. The fusion line and heat-affected zone are completely eliminated; the strength and ductility at the weld joint are essentially consistent with the base material. Under different annealing regimes, uniform grain growth is promoted, eliminating work hardening while controlling the average grain size of the GH3536 strip, further ensuring high strength and ductility. Therefore, this invention, by optimizing the vacuum electron beam welding process and the rolling-annealing process of the billet sheet, develops a 0.3–0.5 mm thick GH3536 strip with high single-coil weight, high temperature alloy content, and stable strong and ductile mechanical properties.

[0024] The advantages and beneficial effects of this invention are:

[0025] 1. This invention performs vacuum electron beam welding on GH3536 billet plates and obtains flat and continuous welds by precisely controlling the welding parameters in segments. The welded joints are free from defects such as holes, collapses, and spatter.

[0026] 2. This invention designs the rolling deformation amount and annealing process of GH3536 alloy plates after welding, so that the rolling deformation amount is more sufficient, the internal structure is more uniform, the intermediate high-temperature rapid annealing suppresses the coarsening of internal grains, and adjusts the grain size and uniformity of the internal structure of the strip and weld joint.

[0027] 3. This invention enables stable production of high-strength, high-ductility GH3536 alloy strip with high single-coil weight, exhibiting uniform and stable performance to meet high-quality requirements. The welded joints of the GH3536 alloy strip achieve equal strength matching with the base material, and the room temperature mechanical properties meet the following requirements: yield strength (Rp0.2) not less than 370 MPa, tensile strength (Rm) not less than 780 MPa, and room temperature elongation (A) not less than 25%.

[0028] 4. The GH3536 alloy strip prepared by this invention has excellent performance and can achieve industrial production with high single-roll weight, meeting the requirements of high-performance aero-engines. Attached Figure Description

[0029] Figures 1-2 For welding joints of blank plates ( Figure 1 ) and welded joints after multi-pass rolling annealing ( Figure 2 Electron backscatter diffraction (EBSD) pattern. Detailed Implementation

[0030] In practical implementation, domestically produced strip has low single-coil weight, unstable performance, and unreliable quality. The specific process for vacuum electron beam welding of GH3536 billet and sheet metal according to this invention is as follows: chemical cleaning of the base material before welding → assembly and clamping → vacuuming → segmented electron beam welding → cooling in a vacuum chamber. The vacuum electron beam welding process is optimized to obtain a well-formed weld free of porosity and cracks. Furthermore, by selecting the deformation amount during intermediate rolling and the annealing regime, the recrystallization grain size of the GH3536 alloy strip and the weld joint is effectively controlled. The GH3536 alloy strip prepared by this invention has high single-coil weight, good mechanical properties, and the weld joint achieves equal strength matching with the base material. The room temperature mechanical properties of both the GH3536 alloy strip and the weld joint meet the requirements.

[0031] The present invention will be further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments, unless otherwise specified, were performed according to conventional methods and conditions.

[0032] Example 1

[0033] In this embodiment, GH3536 alloy strip coil with a thickness of 4.5mm and a matte surface finish is selected as the blank material. By weight percentage, its specific composition and content are as follows: Cr: 20.5, Fe: 18.8, Mo: 9.06, Co: 1.02, W: 0.60, C: 0.094, Al: 0.15, Si: 0.25, Mn: 0.42, S<0.001, P: 0.004, Ni balance.

[0034] The specific steps for vacuum electron beam welding of the blank sheet are as follows:

[0035] 1. The edges of the plates to be welded are machined to ensure the smoothness and straightness of the edges, and the surface roughness of the edges is 0.3μm;

[0036] 2. Before welding, chemically clean the base material and gaskets, and then dry them.

[0037] 3. Assemble the plates. To ensure welding quality, the gap at the weld joint after assembly should be ≤0.1mm.

[0038] 4. Evacuate the vacuum chamber until the pressure inside is below 1×10⁻⁶. -4 mbar;

[0039] 5. Electron beam welding is used for positioning welding of the weld seam to control the deformation of the component during the formal welding process.

[0040] The process parameters for positioning welding are as follows: voltage 60kV, welding speed 1000mm / min, focusing current 2345mA, beam current 9.5mA, welding heat input 34J / mm, and X and Y direction oscillation amplitude 0.6mm.

[0041] 6. Formal Welding: The weld seams of the high-temperature alloy GH3536 plate after the tack welding are then subjected to formal welding, using segmented welding. The process parameters for formal welding are as follows: For the first 70% of the weld length, voltage is 60kV, welding speed is 1000mm / min, focusing current is 2345mA, and X and Y direction oscillation amplitude is 0.6mm; For the last 30% of the weld length, voltage is 60kV, welding speed is 1000mm / min, focusing current is 2345mA, and X and Y direction oscillation amplitude is 0.6mm. The electron beam current and welding heat input parameters for segmented welding are shown in Table 1.

[0042] Table 1

[0043]

[0044] 7. After welding, cool the sample in a vacuum chamber for 15 minutes before removing it;

[0045] 8. X-ray inspection of the weld area revealed no cracks, incomplete penetration, or lack of fusion inside the weld.

[0046] The intermediate rolling-annealing design parameters for the 4.5mm thick sheet after welding are shown in Table 2.

[0047] Table 2

[0048] path Pre-rolling thickness / mm Thickness after rolling / mm Deformation amount / % Annealing temperature / °C Belt speed (m / min) First rolling process 4.5 3.0 33.3 1150 20 Second rolling process 3.0 2.0 33.3 1145 16 Third rolling process 2.0 1.0 50.0 1130 12 Fourth rolling process 1.0 0.5 50.0 1080 1

[0049] The 0.5mm thick strip after final rolling is annealed at 1080℃ with a belt speed of 1m / min.

[0050] The obtained strip was tested, and the performance indicators of the welded joint of the 0.5mm thick strip were: tensile strength 793MPa, yield strength 400MPa, elongation 29.8%; the tensile strength of the 0.5mm thick strip was 792MPa, yield strength 375MPa, elongation 34%. After rolling and annealing, the strength of the welded joint was matched with that of the base material.

[0051] like Figures 1-2 As shown, the welded joint of the blank plate ( Figure 1 ) and welded joints after multi-pass rolling annealing ( Figure 2 The electron backscatter diffraction (EBSD) pattern of the weld joint shows that the temperature of the molten pool region drops rapidly after the electron beam leaves the initial weld joint. Then, the molten metal at both ends of the molten pool begins to nucleate non-uniformly, and the grains grow outward from the center of the molten pool to form a tightly packed columnar crystal region with different grain orientations from the base material. After multiple rolling annealing processes, the grain orientation of the joint tends to be consistent with that of the base material, and the average grain size is small, indicating that multiple rolling annealing processes can improve the microstructure of the joint.

[0052] Example 2

[0053] In this embodiment, GH3536 alloy strip coil with a thickness of 4.0 mm and a matte surface finish is selected as the blank material and vacuum electron beam welding is performed on it. The difference from Embodiment 1 is the welding parameters for positioning welding and formal welding.

[0054] The process parameters for positioning welding are: voltage 60kV, welding speed 1000mm / min, focusing current 2325mA, beam current 8.5mA, welding heat input 30J / mm, and X and Y direction oscillation amplitude 0.6mm.

[0055] The formal welding process parameters are as follows: For the first 70% of the weld length, the voltage is 60kV, the welding speed is 1000mm / min, the focusing current is 2325mA, and the X and Y direction oscillation amplitude is 0.6mm; for the last 30% of the weld length, the voltage is 60kV, the welding speed is 1000mm / min, the focusing current is 2325mA, and the X and Y direction oscillation amplitude is 0.6mm. The electron beam current and welding heat input parameters for segmented welding are shown in Table 3.

[0056] Table 3

[0057]

[0058] After welding, the sample was removed after cooling in a vacuum chamber for 15 minutes.

[0059] X-ray flaw detection was performed on the weld area, and no cracks, incomplete penetration, or lack of fusion were found inside the weld.

[0060] The intermediate rolling-annealing design parameters for the 4.0mm thick sheet after welding are shown in Table 4.

[0061] Table 4

[0062] path Pre-rolling thickness / mm Thickness after rolling / mm Deformation amount / % Annealing temperature / °C Belt speed (m / min) First rolling process 4.0 2.5 37.5 1145 18 Second rolling process 2.5 1.6 36.0 1140 15 Third rolling process 1.6 0.7 56.3 1110 10 Fourth rolling process 0.7 0.3 57.1 1050 0.5

[0063] The 0.3mm thick strip after final rolling is annealed at 1050℃ with a belt speed of 0.5m / min.

[0064] The obtained strip was tested, and the performance indicators of the welded joint of the 0.3mm thick strip were: tensile strength 809MPa, yield strength 392MPa, elongation 26.6%; the tensile strength of the 0.3mm thick strip was 801MPa, yield strength 382MPa, elongation 30%. After rolling and annealing, the strength of the welded joint was matched with that of the base material.

[0065] The results show that the present invention performs vacuum electron beam welding on GH3536 billet plates and obtains flat and continuous welds by precisely controlling the welding parameters in segments. The welded joints are free of defects such as holes, collapses, and spatter. The rolling-annealing process of the billet plates after welding is optimized. This method can achieve uniform internal structure of the strip and the strip welded joints, and can obtain high single-coil weight high-temperature alloy strips with equal strength matching between the welded joints and the base material and meeting the mechanical property requirements.

Claims

1. A method for preparing nickel-based wrought superalloy strip that can increase the weight of a single roll, characterized in that, Vacuum electron beam welding is performed on a nickel-based wrought superalloy blank plate, the nickel-based wrought superalloy is GH3536 alloy, comprising the following steps: (1) The edges of the blank to be welded are all subjected to mechanical processing to ensure the smoothness and flatness of the edges, and the surface roughness of the edges is less than 0.5 μm; (2) The base material is subjected to chemical cleaning before welding, and is subjected to drying treatment after cleaning; (3) The blank is welded, in order to ensure the welding quality, the gap at the weld after assembly is ≤0.1mm; (4) The vacuum electron beam welding is used to positionally weld the weld to control the deformation of the assembly in the formal welding process; The process parameters of the positional welding are as follows: voltage 60kV, welding speed 1000mm / min, focusing current 2325~2345mA, beam current 8.5~9.5mA, welding heat input 30J / mm~34J / mm, X, Y direction swing amplitude 0.6mm; (5) The vacuum electron beam welding is used to formally weld the weld; The formal welding adopts segmented welding, and the process parameters are as follows: for the first 70% length of the weld, voltage 60kV, welding speed 1000mm / min, focusing current 2325~2345mA, beam current 27~28mA, welding heat input 97J / mm~100J / mm, X, Y direction swing amplitude 0.6mm; for the last 30% length of the weld, voltage 60kV, welding speed 1000mm / min, focusing current 2325~2345mA, beam current 26~27mA, welding heat input 94J / mm~97J / mm, X, Y direction swing amplitude 0.6mm; (6) After welding, the plate is cooled in the vacuum chamber for 15min; The nickel-based wrought superalloy blank plate after welding is subjected to four rolling passes on a precision rolling mill, the deformation of the first two rolling passes is 30%~40%, the deformation of the last two rolling passes is 50%~60%, the thickness of the rolled strip is controlled to be 0.3~0.5mm, so that the nickel-based wrought superalloy strip has deformation energy storage beneficial to the recrystallization nucleation in the later period; (7) The weld area is subjected to X-ray flaw detection, and the entire weld is not allowed to have cracks, incomplete penetration and incomplete fusion.

2. The method of claim 1, wherein the nickel-base wrought superalloy strip having increased single length weight is characterized by: Immediately after each rolling pass, high-temperature intermediate flexible bright annealing is performed, and the annealing temperature between rolling passes is controlled as follows: after the first three rolling passes, the annealing temperature is 1110~1150 °C, and the strip running speed is 10~20 m / min; after the last rolling pass, the annealing temperature is 1050~1100 °C, and the strip running speed is 0.5~1 m / min.

3. The method of claim 2, wherein the nickel-base wrought superalloy strip having increased single length weight is characterized by: The annealing equipment is selected to be a continuous ammonia decomposition heat treatment furnace or a hydrogen gas protection continuous heat treatment furnace.

4. The method of claim 1 wherein the nickel-base wrought superalloy strip having increased single length weight is characterized by, The room temperature mechanical properties of the GH3536 alloy strip and the welded joint meet the following requirements: the yield strength Rp0.2 is not less than 370MPa, the tensile strength Rm is not less than 780 MPa, the room temperature elongation A is not less than 25%, and the rolled welded joint and the base material realize equal strength matching.

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