A vacuum electron beam welding method for a nickel-based wrought high-temperature alloy foil for an aero-engine

Abstract

The present application belongs to the technical field of high-temperature alloy foil preparation, and particularly relates to a vacuum electron beam welding method for nickel-based wrought high-temperature alloy foil for an aero-engine. The vacuum electron beam welding method is used for micron-scale (30-80 mu m) nickel-based wrought high-temperature alloy foil, and the process is as follows: chemical cleaning of the base material, gasket and the like before welding, assembly, clamping, vacuum extraction, electron beam welding, cooling in the vacuum chamber, optimization of the vacuum electron beam welding process, and obtaining an excellent weld with good formation, no pores and cracks, and a tensile strength of the welded joint reaching more than 95% of the tensile strength of the base material. The present application can not only make the welding stable, the weld width uniform, the spatter small and the arc full, but also has the safety and reliability of the structure with the tensile strength of the welded joint being equivalent to that of the base material.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high-temperature alloy foil preparation, and particularly relates to a vacuum electron beam welding method for nickel-based wrought high-temperature alloy foil for an aero-engine. BACKGROUND

[0002] Generally, high-temperature alloy profiles with a thickness greater than 1 mm are referred to as plates, profiles with a thickness of 0.1-0.8 mm are referred to as strips, and profiles with a thickness less than 0.1 mm are referred to as foils. The thickness of a metal foil is much smaller than the size of the other two dimensions, and the metal foil is a typical micron-scale material. GH3536 is a solid solution strengthening type nickel-based high-temperature alloy, has excellent hot corrosion resistance, oxidation resistance, high-temperature stability and microstructure stability, and can be used for a long time below 900 DEG C, and the short-time working temperature can reach 1080 DEG C. The GH3536 alloy foil can be used to prepare aero-engine combustion liner, turbine exhaust components, aircraft cabin heater and other complex thin-walled high-temperature structural parts, and is a micron-scale material with important application background in the fields of aviation and aerospace. Thin-walled sheet metal parts prepared from micron-scale GH3536 alloy foils account for a considerable proportion in the combustion chamber and turbine structures of aircraft engines, and welding is an important means of connecting these parts. The traditional welding process method is not concentrated in heat, has low welding efficiency, large part deformation, easy oxidation of the weld and easy production of welding defects. The aviation and aerospace fields have high requirements for welding quality, especially for parts and products serving under such high-temperature conditions, and welding defects are one of the important ways of product failure. The vacuum electron beam welding does not need to pass in a protective gas, and the parts are welded in a vacuum state, which greatly reduces the pollution of the surrounding environment to the weld, has the characteristics of strong penetration, fast welding speed, small heat-affected zone, small welding stress, large weld seam depth-width ratio, good welding quality and the like, and is widely used in the fields of aviation and aerospace. When the GH3536 alloy foil is electron beam welded, the base metal undergoes a process of first being heated and melted and then being cooled and solidified. In this process, different welding heat inputs will change the heating and cooling speed of the weld metal, change the microstructure of the weld zone, and finally affect the mechanical properties of the welded joint. From the safety and reliability of the structure, the weld strength is generally required to be at least equal to the base material strength, that is, the "equal strength" design principle. SUMMARY

[0003] The purpose of the application is to provide a vacuum electron beam welding method for nickel-based wrought high-temperature alloy foil for an aero-engine, which has small deformation, beautiful weld forming, no cracks, pores and other defects, and under the optimized welding process parameters, the tensile strength of the joint can reach more than 95% of the tensile strength of the base material.

[0004] The technical scheme of the application is as follows:

[0005] A vacuum electron beam welding method for nickel-based wrought high-temperature alloy foil for an aero-engine, comprising the following steps:

[0006] First step: using nickel-based wrought high-temperature alloy foil with a thickness of 0.03-0.08 mm, and a 2-4 mm thick 316 stainless steel plate as a backing pad;

[0007] Second step: chemically cleaning the base material and the backing pad before welding, and the specific process is: degreasing, water washing, alkali washing, water washing, acid washing, water washing, and drying treatment after cleaning;

[0008] Third step: assembling and clamping, and the gap between the assembled parts is less than 0.01 mm;

[0009] Fourth step: vacuumizing and performing electron beam welding, and the control acceleration voltage is 30 kV, and the focusing current is 1600 mA;

[0010] Fifth step: after welding, the sample is taken out after cooling in the vacuum chamber for 5 min.

[0011] In the third step of the vacuum electron beam welding method for the nickel-based wrought high-temperature alloy foil for the aero-engine, the cleaned nickel-based wrought high-temperature alloy foil is placed on a horizontal workbench, in order to avoid the offset of the welded part caused by deformation during welding, the welding seam is aligned with the slot hole of the upper and lower backing pads, and the backing pad is clamped by a metal clamp, so that the assembly of the welded part is realized.

[0012] In the fourth step of the vacuum electron beam welding method for the nickel-based wrought high-temperature alloy foil for the aero-engine, for the 0.03 mm thick foil: the electron beam current is 0.15-0.2 mA, the welding speed is 36.7 mm / s, and the welding heat input is 0.12-0.16 J / mm; for the 0.05 mm thick foil: the electron beam current is 0.3-0.4 mA, the welding speed is 36.7 mm / s, and the welding heat input is 0.2-0.3 J / mm; for the 0.08 mm thick foil: the electron beam current is 1.1-1.3 mA, the welding speed is 36.7 mm / s, and the welding heat input is 0.9-1.1 J / mm.

[0013] In the fourth step of the vacuum electron beam welding method for the nickel-based wrought high-temperature alloy foil for the aero-engine, for the 0.08 mm thick foil, the welding seam width is 0.4-0.7 mm; for the 0.05 mm thick foil, the welding seam width is 0.1-0.2 mm; and for the 0.03 mm thick foil, the welding seam width is 0.1-0.15 mm.

[0014] In the fourth step of the vacuum electron beam welding method for the nickel-based wrought high-temperature alloy foil for the aero-engine, the nickel-based wrought high-temperature alloy is GH3536 alloy, and the tensile strength of the welded joint is more than 95% of the tensile strength of the base material.

[0015] The design idea of the present application is:

[0016] The thin-wall sheet metal part of the aero-engine combustion chamber, turbine and the like structure made of nickel-based high-temperature alloy GH3536 foil needs to be welded, in order to prevent the welding bead from being oxidized, the part from being deformed greatly, and a series of defects such as incomplete penetration and welding through, the present application adopts vacuum electron beam welding to obtain a welding seam without welding defects and realize equal strength matching of the welding seam strength and the base material strength, and ensure the safety and reliability of the structure. First, in order to prevent welding deformation, reduce the positioning welding process and improve the welding efficiency, a groove-shaped gasket is designed, and the foil is tightly fixed by the assembly tool; second, the welding speed of vacuum electron beam welding is controlled to realize high-speed welding, increase the welding efficiency, and at the same time, the welding seam cooling speed is improved, the crystallization state of the welding seam metal is improved, and the strength of the welding joint is improved; third, the welding heat input is controlled to obtain a welding seam with small width, flatness and continuity, without subsequent polishing processing treatment, and the coarse grain area is avoided to prevent the material performance from being deteriorated. In summary, the vacuum electron beam welding method for the nickel-based deformed high-temperature alloy foil of the aero-engine provided by the present application has small deformation, the welding seam is beautiful, and there are no defects such as cracks and pores, and under the optimized welding process parameters, the tensile strength of the joint can reach more than 95% of the tensile strength of the base material.

[0017] The advantages and beneficial effects of the present application are:

[0018] 1. The vacuum electron beam welding process for the nickel-based deformed high-temperature alloy GH3536 foil provided by the present application has concentrated energy, high power density, low heat input, small heat-affected zone, small deformation and high welding speed.

[0019] 2. The welding seam width of the 0.08mm-thick foil is 0.4-0.7mm, the welding seam width of the 0.05mm-thick foil is 0.1-0.2mm, and the welding seam width of the 0.03mm-thick foil is 0.1-0.15mm, there are no defects such as cracks and pores, and the welding process is stable.

[0020] 3. The present application adopts the vacuum electron beam welding method for the micron-scale (30-80μm) GH3536 alloy foil, optimizes the welding process, obtains an excellent welding seam with good forming, no pores and cracks, and the tensile strength of the welding joint reaches more than 95% of the tensile strength of the base material. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The gasket diagram for the application of GH3536 foil welding.

[0022] Figure 2 (a) is the front macroscopic morphology of the EBW welding seam of the 50μm-thick GH3536 alloy foil when the welding heat input is 0.25J / mm.

[0023] Figure 2 (b) is the back macroscopic morphology of the EBW weld of the 50 μm thick GH3536 alloy foil when the welding heat input is 0.25 J / mm.

[0024] Figure 2 (c) is the front macroscopic morphology of the EBW weld of the 50 μm thick GH3536 alloy foil when the welding heat input is 0.3 J / mm.

[0025] Figure 2 (d) is the back macroscopic morphology of the EBW weld of the 50 μm thick GH3536 alloy foil when the welding heat input is 0.3 J / mm. DETAILED DESCRIPTION

[0026] In the implementation process, for the welding of the GH3536 foil, since the material is very thin, it is easy to burn through, and to obtain a continuous weld without burning through, the key is to accurately control the parameters. The inventor of the present application has proposed a vacuum electron beam welding method for micron-scale (30-80 μm) GH3536 alloy foils by optimizing the vacuum electron beam welding process, and the process is as follows: chemical cleaning of the base material, liner and the like before welding → assembly, clamping → vacuumizing → electron beam welding → cooling in the vacuum chamber.

[0027] The present application will be further described below by way of examples, but the present application is not limited to the scope of the examples. The experimental methods in the following examples are not specified, and are carried out according to the conventional methods and conditions.

[0028] EXAMPLE

[0029] In the examples, the GH3536 alloy foils with thicknesses of 0.03 mm, 0.05 mm and 0.08 mm are selected, and the specific components and contents thereof are as follows in terms of weight percentage: Cr: 21.8, Fe: 19.8, Mo: 8.66, Co: 0.82, W: 0.57, C: 0.086, Al: 0.19, Si: 0.21, Mn: 0.72, Cu: 0.05, S: 0.001, P: 0.005, and Ni balance.

[0030] The vacuum electron beam welding method is used, and the specific steps are as follows:

[0031] 1. The GH3536 alloy foils with thicknesses of 0.03 mm, 0.05 mm and 0.08 mm, and the liner is a 2-4 mm thick 316 stainless steel plate.

[0032] 2. The base material, liner and the like are chemically cleaned before welding, and the specific process is as follows: degreasing → water washing → alkali washing → water washing → acid washing → water washing and the like, and the cleaned material is dried.

[0033] 3. Connect the parts to be welded, ensuring that the gap between the two parts is no more than 0.001mm. Align the weld seam with the upper and lower backing slots and clamp the backing with metal clamps to assemble the parts.

[0034] 4. Vacuum is drawn and electron beam welding is performed. The process parameters are as follows: the accelerating voltage is controlled at 30kV and the focusing current is 1600mA. The specific vacuum electron beam welding process is shown in Table 1.

[0035] Table 1

[0036]

[0037] X-ray flaw detection was performed on the weld area. No cracks, incomplete penetration, incomplete fusion, or burn-through were found inside the weld. The tensile strength of the sample and the ratio of its tensile strength to the tensile strength of the base material are shown in Table 2.

[0038] Table 2

[0039]

[0040] like Figure 1 The diagram shows a backing plate used for welding GH3536 foil. As can be seen from the diagram, the designed groove-shaped backing plate, along with the assembly fixtures, presses and fixes the foil to prevent welding deformation, reduce the number of tack welding steps, and improve welding efficiency.

[0041] like Figure 2 As shown in (a)-(d), the macroscopic morphology of the EBW weld of 50μm thick GH3536 alloy foil is as follows. It can be seen from the figure that, regardless of whether the welding heat input is 0.25J / mm or 0.3J / mm, the weld is narrow, flat and continuous on both the front and back sides, and no subsequent grinding processing is required.

[0042] The results show that the vacuum electron beam welding method of the present invention can not only make the welding stable, the weld width uniform, the spatter small and the arc full, but also make the tensile strength of the welded joint comparable to that of the base material, with structural safety and reliability, good weld formation, bright weld surface and no defects such as pores or cracks.

Claims

1. A vacuum electron beam welding method for nickel-based wrought high-temperature alloy foils used in aero-engines, characterized in that, Includes the following steps: Step 1: Use nickel-based wrought high-temperature alloy foil with a thickness of 0.03~0.08 mm, and use 2~4 mm thick 316 stainless steel plate as backing; Step 2: Chemical cleaning of the base material and gasket before welding. The specific process is: degreasing → water washing → alkaline washing → water washing → acid washing → water washing, followed by drying. Step 3: Assembly and clamping, with an assembly gap of less than 0.01mm; Step 4: Vacuuming and electron beam welding are performed, with the accelerating voltage controlled at 30 kV and the focusing current at 1600 mA. In the fourth step, for 0.03 mm thick foil: electron beam current 0.15~0.2 mA, welding speed 36.7 mm / s, welding heat input 0.12~0.16 J / mm; for 0.05 mm thick foil: electron beam current 0.3~0.4 mA, welding speed 36.7 mm / s, welding heat input 0.2~0.3 J / mm; for 0.08 mm thick foil: electron beam current 1.1~1.3 mA, welding speed 36.7 mm / s, welding heat input 0.9~1.1 J / mm; Step 5: After welding, cool the sample in the vacuum chamber for 5 minutes, then remove it. The nickel-based wrought high-temperature alloy is GH3536 alloy, and the tensile strength of the welded joint is more than 95% of the tensile strength of the base material.

2. The vacuum electron beam welding method for nickel-based wrought high-temperature alloy foil for aero-engines according to claim 1, characterized in that, In the third step, the cleaned nickel-based deformed high-temperature alloy foil is placed on a horizontal workbench. In order to avoid the weldment from shifting due to deformation during welding, the weld is aligned with the slots of the upper and lower pads, and the pads are clamped with metal clamps to achieve the assembly of the weldment.

3. The vacuum electron beam welding method for nickel-based wrought high-temperature alloy foil for aero-engines according to claim 1, characterized in that, For foil with a thickness of 0.08 mm, the weld width is 0.4~0.7 mm; for foil with a thickness of 0.05 mm, the weld width is 0.1~0.2 mm; for foil with a thickness of 0.03 mm, the weld width is 0.1~0.15 mm.

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