Electron beam welding method for fragile material

Abstract

The invention belongs to the technical field of material processing and welding, and provides an electron beam welding method for a fragile material, which comprises the following steps of: dividing a first stress regulation and control area covering a welding joint and a second stress regulation and control area positioned on the outer side of the first stress regulation and control area on a to-be-welded workpiece; differential heating is conducted on the two areas, so that the heating temperature of the second area is higher than that of the first area; based on the heating temperature of the first stress regulation and control area, welding parameters are determined by adopting a method of combining parameter calculation and test welding verification; welding operation is conducted in a dynamic beam adjusting mode according to the welding parameters; and performing scanning heating on a welding seam area after welding to realize cold treatment. According to the method, welding cracks of the fragile material are fundamentally restrained through an active stress regulation and control mechanism, meanwhile, the preheating process is optimized, assembly deformation caused by overall high temperature is avoided, and high-quality and high-efficiency welding is achieved in combination with a welding parameter confirmation and forming control method.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of material processing and welding, and relates to an electron beam welding method for a brittle material. BACKGROUND

[0002] With the increasing demand for high-performance structural components in the fields of aerospace, energy and power, new high-temperature-resistant and high-strength materials such as Ti2AlNb alloy, GH4151 high-temperature alloy and GH4065A high-temperature alloy are widely used in new component structures such as casings, rotors and discs. However, these materials generally have the characteristics of narrow crystallization temperature range, low thermal conductivity and poor high-temperature plasticity, and are prone to defects such as thermal cracks and liquidization cracks during welding, which are called "brittle materials".

[0003] Electron beam welding is the preferred process for connecting such high-performance components due to its high energy density, large depth-to-width ratio, narrow heat-affected zone and non-pollution in a vacuum environment. However, for the above-mentioned new component structures such as Ti2AlNb alloy with a thickness of 2mm to 6mm, in order to suppress welding cracks, electron beam scanning or overall auxiliary heating methods are currently mainly used to preheat and weld the welding position to reduce welding cracks. However, this method still faces the following severe challenges: 1. Local intense heating and rapid cooling during welding result in huge welding tensile stress in the weld area, which easily cracks at the solidification end or high-temperature cooling stage when the material's high-temperature strength is insufficient to resist the stress; 2. Although overall preheating can reduce the cooling speed and residual stress, the electron gun is easily heated in reverse in a high-temperature environment, causing equipment aging; a preheating temperature that is too high at the welding position can cause changes in the assembly gap and height difference (step difference) between the two abutted plates due to uneven expansion, reducing assembly precision and affecting welding quality; and a welding position that is preheated too high can affect observation during welding, which is not conducive to the centering of the welding position / weld; 3. The thermal physical state under preheating conditions is significantly different from that under conventional welding, and directly applying conventional parameters can easily lead to incomplete penetration, excessive melting or poor forming. The existing technology relies on experience and trial-and-error to determine process parameters, which is low in efficiency and high in cost; 4. The thermal accumulation effect during welding causes the temperature of the second half of the weld to be too high, which easily produces surface defects such as undercut and depression, making it difficult to control the forming of the weld; 5. Under the combined action of structural restraint stress and welding stress, electron beam welding still has welding cracks.

[0004] In addition, although the prior art attempts to improve by local preheating or auxiliary heating, it is mostly limited to "reducing the cooling speed", and fails to fundamentally solve the core cause of the crack generated by the welding tensile stress, and lacks a systematic process parameter determination method. Therefore, developing a new method of electron beam welding that can actively regulate welding stress, efficiently determine process parameters, significantly inhibit cracks, and ensure the forming quality of the weld is a technical problem that needs to be solved in the field. SUMMARY

[0005] In order to overcome the above-mentioned deficiencies in the prior art, the present application discloses an electron beam welding method for easy cracking materials, which aims to actively form a pre-compressive stress in the weld area to balance the welding tensile stress through an innovative differential heating strategy in different regions, and fundamentally inhibit the generation of cracks. At the same time, a systematic process parameter confirmation method is provided to realize the rapid and accurate determination of welding parameters and forming optimization, and finally obtain high-quality and crack-free welded joints.

[0006] Specifically, the method comprises the following steps: S1, selecting two different stress regulation regions in the joint area of the workpieces to be welded, the stress regulation regions covering a first stress regulation region of the welded joint and a second stress regulation region located outside the first stress regulation region; S2, differentially heating the first stress regulation region and the second stress regulation region according to a designed preheating temperature gradient, so that the heating temperature of the second stress regulation region is greater than the heating temperature of the first stress regulation region, and a compressive stress generated by thermal expansion is formed at the position of the welded joint; S3, based on the heating temperature of the first stress regulation region, determining the welding parameters by combining parameter calculation with trial welding verification; S4, performing welding operation on the two workpieces to be welded subjected to differential heating by using a dynamic beam current adjustment method according to the welding parameters; S5, after the welding is completed, scanning and heating the weld area for post-welding slow cooling treatment.

[0007] Further, in step S2, the first stress regulation region is heated by an electron beam, and the second stress regulation region is heated by an auxiliary heating device.

[0008] Further, in step S2, the difference between the heating temperature of the second stress regulation region and the heating temperature of the first stress regulation region is greater than 50℃.

[0009] Further, in step S3, based on the heating temperature of the first stress regulation region, the welding parameters are determined by combining parameter calculation with trial welding verification, including: S31, determining an initial welding current range according to the ratio and an empirical value of welding current under normal temperature condition; S32, under the differential heating condition, using continuously changing welding current to perform trial welding, optimizing the initial welding current range according to the weld forming quality to obtain final welding parameters.

[0010] Further, in step S3, the ratio A is expressed as A=T0 / T m , wherein T0 is the heating temperature of the first stress control region, T m is the melting point of the workpiece material; The welding current I b ′ is expressed as I b ′ =I b0 ×(1-A), wherein I b0 is the empirical value of welding current under normal temperature condition, and the range of the initial welding current is (I b ′ -5)~ I b ′ .

[0011] Further, in step S4, the dynamic beam current adjustment mode is: taking the starting end of the weld as the starting point, and when traveling to the interval of 1 / 2~3 / 4 of the weld length in the welding direction, the welding current is reduced by 5%~15%.

[0012] Further, in step S1, the width of the first stress control region is 10~50mm, and the distance between the second stress control region and the edge of the first stress control region is 10~50mm.

[0013] Further, in step S1, the workpiece to be welded is an intermetallic compound or a high-temperature alloy.

[0014] In one embodiment of the above electron beam welding method of the easy-to-crack material, the method further comprises: S0, designing a margin compensation value of the welded joint according to a given preheating welding margin.

[0015] Further, when the welding margin Δδ under normal temperature condition is greater than or equal to a set value, the margin compensation value is the preheating welding margin; and when the welding margin Δδ under normal temperature condition is less than the set value, the margin compensation value is the sum of the welding margin under normal temperature condition and the preheating welding margin.

[0016] Compared with the prior art, the present application has the following remarkable beneficial effects: 1. By actively generating preheating expansion compressive stress in the weld area through "regional differentiated heating", the preheating compressive stress can effectively offset the tensile stress generated during the welding process, reduce the driving force for crack generation from the mechanical source, significantly improve the crack resistance of the welded joint, and improve the reliability of the joint. This is an effect that overall preheating technology cannot achieve.

[0017] 2. The preheating temperature gradient design of "external heat and internal cold" is adopted for the two stress control areas, so that the preheating temperature of the first stress control area (i.e. the weld joint) which is the core area of ​​welding is lower, effectively reducing the overall thermal deformation of the workpiece, thereby avoiding changes in assembly gap and step due to high temperature, and ensuring the alignment accuracy and process stability of welding.

[0018] 3. By designing the ratio A = T0 / T m This provides a theoretical basis for the conversion of welding parameters under preheating conditions, and realizes the scientific derivation from welding parameters under room temperature conditions to the final welding parameters. Combined with the "continuous variable beam current test welding" method, the optimal welding parameters can be determined quickly and intuitively, significantly improving the efficiency of process development.

[0019] 4. The "dynamic beam adjustment" technology effectively compensates for the heat accumulation effect during the welding process, avoiding defects such as undercut and depression caused by overheating in the latter half of the weld, ensuring that the entire weld is uniform and aesthetically pleasing, and guaranteeing the formation of a high-quality weld.

[0020] 5. Post-weld slow cooling treatment further reduces the cooling rate, which is beneficial to obtaining a more uniform and finer microstructure and improving the overall mechanical properties of the joint.

[0021] In summary, this invention provides a complete, efficient, and innovative electron beam welding solution, which is particularly suitable for high-quality welding of refractory and easily cracked materials such as Ti2AlNb, GH4151, and GH4065A, and has broad application prospects. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 A flowchart of an electron beam welding method for easily crackable materials; Figure 2 This is a schematic diagram of two stress control zones on a workpiece to be welded. Figure 3 A schematic diagram of the heating of the first stress control region and the second stress control region; Figure 4 A schematic diagram for designing the margin compensation value. Detailed Implementation

[0024] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0025] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features of the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] This invention discloses an electron beam welding method for easily cracked materials. See [link to relevant documentation]. Figure 1 As shown, the method includes the following steps: S1. Select two different stress control areas in the joint area of ​​the workpiece to be welded. The stress control areas cover the first stress control area of ​​the welded joint and the second stress control area located outside the first stress control area. S2. According to the designed preheating temperature gradient, the first stress control area and the second stress control area are heated differently, so that the heating temperature of the second stress control area is greater than that of the first stress control area, and compressive stress caused by thermal expansion is formed at the welding joint position. S3. Based on the heating temperature of the first stress control region, the welding parameters are determined by combining parameter calculation with trial welding verification. S4. Based on the welding parameters, a dynamic beam current adjustment method is used to perform welding operations on two workpieces to be welded with different heating. S5. After welding, scan and heat the weld area and perform post-weld slow cooling treatment.

[0027] In one embodiment, in step S1, the workpiece to be welded is an intermetallic compound or a high-temperature alloy, such as workpiece 1 with a thickness of 2-6 mm and made of Ti2AlNb material. See also Figure 2As shown, the first stress control area 3, also known as the main preheating area, covers the welded joint 2 and has a width of 10-50 mm. The second stress control area 4, also known as the auxiliary preheating area, is 10-50 mm away from the edge of the first stress control area 3.

[0028] In one embodiment, in step S2, an electron beam is used to heat the first stress-regulating region, and an auxiliary heating device is used to heat the second stress-regulating region. For specific implementation details, see [link to implementation details]. Figure 3 As shown, preheating can be achieved in the first stress control zone 3 using a defocused electron beam 5 for cyclic scanning heating. Adjusting the electron beam to center the welding position during scanning can improve the accuracy of regional heating and effectively clean the surface of the welding position. The second stress control zone 4 is heated using an auxiliary heating belt 6 inside a vacuum chamber, which can achieve auxiliary heating of areas other than the welding position, and the heating temperature can be flexibly controlled.

[0029] In one embodiment, in step S2, the difference between the heating temperature of the second stress-regulating region and the heating temperature of the first stress-regulating region is greater than 50°C.

[0030] During preheating, the two workpieces 1 to be welded are aligned and assembled inside the vacuum chamber, while the first stress control region 3 and the second stress control region 4 are preheated simultaneously. Specifically, for the first stress control region 3, the electron beam center position is adjusted to align with the welding position center, and a defocused electron beam 5 is used for cyclic scanning heating 10-20 times, with a preheating time of 10-30 minutes and a preheating temperature set to 200℃-300℃. For the second stress control region 4, an auxiliary heating belt 6 inside the vacuum chamber is used for overall preheating via direct thermal radiation; the preheating temperature can be set to 350℃-450℃, and the preheating holding time is 10-30 minutes.

[0031] By designing a temperature difference between the main preheating zone and the auxiliary heating zone, a temperature gradient is formed. Before welding, thermal expansion compressive stress is generated at the welding position. During welding, a portion of the welding tensile stress can be balanced and offset, thereby reducing welding stress and further reducing the probability of crack defects.

[0032] By using a dual-zone design with a main preheating zone and an auxiliary preheating zone, and by designing differentiated heating temperatures for the two zones, the preheating temperature at the welding position can be reduced, thus reducing variations in assembly accuracy at the welding position. Preheating can also reduce welding cooling, and the preheating expansion stresses in the main preheating zone and the auxiliary preheating zone are balanced with each other, which can reduce welding tensile stress.

[0033] In one embodiment, in step S3, based on the heating temperature of the first stress-regulating region, welding parameters are determined using a method combining parameter calculation and trial welding verification, including: S31. Determine the initial welding beam range based on the ratio of the heating temperature of the first stress control region to the melting point of the workpiece material, and the empirical value of the welding beam under normal temperature conditions. S32. Under differentiated heating conditions, a trial welding is performed using a continuously varying welding beam. The initial welding beam range is optimized based on the weld formation quality to obtain the final welding parameters.

[0034] In practice, steps S31 and S32 involve using a welding test plate and conducting electron beam welding process experiments under ambient temperature welding conditions by adjusting parameters such as accelerating voltage, focusing current, welding beam current, and welding speed. This process allows for the flexible and rapid determination of electron beam welding parameters.

[0035] Compared to welding at room temperature, the input of preheating energy affects the welding heat input energy. To simplify the influence of preheating energy on weld penetration and forming, a ratio A of the heating temperature in the first stress control zone to the melting point of the workpiece material is proposed. This ratio can also be called the preheating influence coefficient, which is expressed as: A = T0 / T m Where T0 is the heating temperature of the first stress control region, T m The melting point of the workpiece material; the corresponding preheating welding heat input energy E H =E×(1-A), where E is the welding heat input energy under normal temperature conditions. Under accelerating voltage Ua and focusing current I... f Under constant parameters such as welding speed v, the main change is in the welding beam current. If the empirical value of the welding beam current at room temperature is I... b0 The expected welding beam current I b ′ Will be represented as I b ′ =I b0 ×(1-A). Taking into account the preheating effect, the range of the initial welding beam can be designed as (I b ′ -5) ~ I b ′ This invention, by proposing a preheating influence coefficient based on welding parameters under normal temperature conditions, can quickly and preliminarily determine preheating welding process parameters, reducing the number of preheating welding tests and lowering the difficulty of process testing.

[0036] The welding test plate was preheated to a suitable temperature between 300 and 500°C in a vacuum chamber, using (I) b ′ -5) → I b ′ Continuous variable beam welding was performed, and welding spatter, penetration, and weld formation on the front side were observed. The beam current corresponding to the well-formed positions on both sides was selected as the welding beam current parameter I. bWelding is performed using a defocused electron beam. The weld seam is obtained by continuously varying the welding beam current. The weld seam formation is observed and analyzed to determine the welding beam current, thus achieving weld penetration and forming.

[0037] In one embodiment, in step S4, the dynamic beam current adjustment method is as follows: starting from the weld start end, when the welding beam current travels along the welding direction to the interval of 1 / 2 to 3 / 4 of the weld length, the welding beam current is reduced by 5% to 15%.

[0038] In practice, a test plate can be selected during the preheating welding process to observe welding spatter and weld surface formation. A point within the range of 1 / 2L to 3 / 4L along the length of the workpiece can be arranged, and the welding beam current can be finely adjusted by 10%, that is, the welding beam current is reduced to 90%×I. b This is done to improve weld formation, where L is the length of the entire weld. By fine-tuning the welding beam, the impact of accumulated heat from previous welding is reduced, avoiding excessively high pre-weld temperatures that could lead to large undercuts and depressions, thus improving weld formation quality.

[0039] In one embodiment, in step S5, after welding is completed, electron beam welding is performed by adjusting the electron beam alignment welding position. After welding, the weld seam is cyclically scanned and heated 10-20 times using a defocused electron beam to achieve slow cooling treatment after welding, thereby further reducing welding stress.

[0040] In one embodiment of the electron beam welding method for the aforementioned easily cracked materials, the method further includes: S0. Based on the given preheating welding allowance, design the allowance compensation value for the welded joint.

[0041] In one embodiment, when the welding allowance Δδ under normal temperature conditions is greater than or equal to a set value, the allowance compensation value is the preheating welding allowance; when the welding allowance Δδ under normal temperature conditions is less than the set value, the allowance compensation value is the sum of the welding allowance under normal temperature conditions and the preheating welding allowance.

[0042] During implementation, the characteristics of the welded structure on the workpiece can be considered, along with the influence of the preheating process. The preheating welding allowance can be set to 2mm, and a comprehensive welding allowance design can be performed. For example... Figure 4 As shown, the corresponding welded joint 2 on workpiece 1 has a weld structure thickness of δ, a welding allowance of Δδ at room temperature, and a preheating welding allowance of Δδ′. When the welding allowance Δδ at room temperature is ≥ 2mm, the preheating welding allowance Δδ′ is designed to be 2mm; if the welding allowance Δδ at room temperature is < 2mm, the preheating welding allowance Δδ′ is Δδ + 2mm. Preheating welding increases the risk of surface defects such as undercut and depressions. By comprehensively designing the welding allowance, the influence of preheating on the weld surface formation is compensated, which is beneficial to improving the surface quality and dimensional accuracy of the processed material.

[0043] This invention takes a Ti2AlNb material butt joint structure with a thickness of 4mm and a size of 100mm×100mm as an example, and performs a preheating electron beam welding operation. The specific process is as follows: (1) Preheating zone design: including the first stress control zone 3 and the second stress control zone 4, such as Figure 2 As shown, the main preheating zone 3 has a width of 30mm and a length of 130mm (the current-gathering block is 15mm long); a second stress control zone 4 with a width of 30mm and a length of 100mm is designed on one side at a distance of 30mm from the welding position.

[0044] (2) Preheating method design: In the first stress control area 3, the defocused electron beam 5 is used for cyclic scanning heating. In the second stress control area 4, the vacuum chamber auxiliary heating belt 6 is used for heating.

[0045] (3) Preheating process design: The first stress control zone 3 and the second stress control zone 4 are preheated simultaneously. The first stress control zone 3 is heated by electron beam cyclic scanning for 20 minutes and the preheating temperature is 300℃; the second stress control zone 4 is preheated at 400℃ and the holding time is 20 minutes.

[0046] (4) Welding and post-weld treatment: After preheating, the weld is heated by defocused electron beam cyclic scanning 15 times, and then slow cooling treatment is performed.

[0047] (5) Welding quality inspection: No cracks or defects were found in the post-weld visual inspection and X-ray inspection, which met the design requirements.

[0048] This invention also uses a butt joint structure of Ti2AlNb material with a thickness δ=5mm and dimensions of 200mm×100mm as an example to illustrate the process of determining welding parameters: (1) Design the thickness allowance of the welded joint: The welding allowance under normal temperature conditions is Δδ=2mm, and the welding allowance Δδ′ after preheating is also designed to be 2mm, that is, the welding thickness δ=7mm.

[0049] (2) Initial welding beam range design: The parameters such as welding acceleration voltage of 150kV, focusing current of 3420mA, welding beam current of 30mA and welding speed of 20mm / s under normal temperature conditions were determined by experiment; the preheating temperature was designed to be 400℃, the melting point of the material was calculated to be 1600℃, the corresponding preheating influence coefficient A=0.25, and the preheating welding beam current could be initially designed to be 17.5 mA~22.5mA, while other parameters remained unchanged.

[0050] (3) Welding process parameter control: preheating to 400℃, using continuous variable beam current welding of 17.5 mA~22.5 mA, and selecting 21 mA welding beam current based on comprehensive penetration and forming analysis.

[0051] (4) Welding formation optimization: The beam fine-tuning position 6 along the welding length is designed to be 150mm, that is, the welding beam current of the last 50mm length is fine-tuned from 21mA to 19mA.

[0052] (5) Welding quality inspection: No cracks or defects were found in the post-weld visual inspection and X-ray inspection, which met the design requirements.

[0053] Compared with the prior art, the present invention has the following significant advantages: 1. By actively generating preheating expansion compressive stress in the weld area through "regional differentiated heating", the preheating compressive stress can effectively offset the tensile stress generated during the welding process, reduce the driving force for crack generation from the mechanical source, significantly improve the crack resistance of the welded joint, and improve the reliability of the joint. This is an effect that overall preheating technology cannot achieve.

[0054] 2. The preheating temperature gradient design of "external heat and internal cold" is adopted for the two stress control areas, so that the preheating temperature of the first stress control area (i.e. the weld joint) which is the core area of ​​welding is lower, effectively reducing the overall thermal deformation of the workpiece, thereby avoiding changes in assembly gap and step due to high temperature, and ensuring the alignment accuracy and process stability of welding.

[0055] 3. By designing the ratio A = T0 / T m This provides a theoretical basis for the conversion of welding parameters under preheating conditions, and realizes the scientific derivation from welding parameters under room temperature conditions to the final welding parameters. Combined with the "continuous variable beam current test welding" method, the optimal welding parameters can be determined quickly and intuitively, significantly improving the efficiency of process development.

[0056] 4. The "dynamic beam adjustment" technology effectively compensates for the heat accumulation effect during the welding process, avoiding defects such as undercut and depression caused by overheating in the latter half of the weld, ensuring that the entire weld is uniform and aesthetically pleasing, and guaranteeing the formation of a high-quality weld.

[0057] 5. Post-weld slow cooling treatment further reduces the cooling rate, which is beneficial to obtaining a more uniform and finer microstructure and improving the overall mechanical properties of the joint.

[0058] In summary, this invention provides a complete, efficient, and innovative electron beam welding solution, which is particularly suitable for high-quality welding of refractory and easily cracked materials such as Ti2AlNb, GH4151, and GH4065A, and has broad application prospects.

[0059] Obviously, those skilled in the art should understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Various modifications and variations of the embodiments of the present invention are possible for those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0060] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An electron beam welding method for easily cracked materials, characterized in that, include: Two different stress control regions are selected in the joint area of ​​the workpiece to be welded. The stress control regions cover the first stress control region of the welded joint and the second stress control region located outside the first stress control region. According to the designed preheating temperature gradient, the first stress control region and the second stress control region are heated differently, so that the heating temperature of the second stress control region is greater than that of the first stress control region, and compressive stress caused by thermal expansion is formed at the weld joint position. Based on the heating temperature of the first stress control region, the welding parameters are determined by combining parameter calculation with trial welding verification. Based on the welding parameters, a dynamic beam current adjustment method is used to perform welding operations on two workpieces with different heating characteristics; After welding, the weld area is scanned and heated, and then subjected to slow cooling treatment.

2. The electron beam welding method for easily cracked materials according to claim 1, characterized in that, The first stress-regulating region is heated using an electron beam, and the second stress-regulating region is heated using an auxiliary heating device.

3. The electron beam welding method for easily cracked materials according to claim 1, characterized in that, The difference between the heating temperature of the second stress-regulating region and the heating temperature of the first stress-regulating region is greater than 50°C.

4. The electron beam welding method for easily cracked materials according to claim 1, characterized in that, Based on the heating temperature of the first stress-controlled region, welding parameters are determined using a combination of parameter calculation and trial welding verification, including: The initial welding beam range is determined by the ratio of the heating temperature of the first stress control region to the melting point of the workpiece material, based on the ratio and the empirical value of the welding beam under normal temperature conditions. Under differentiated heating conditions, trial welding is performed using a continuously varying welding beam. The initial welding beam range is optimized based on the weld formation quality to obtain the final welding parameters.

5. The electron beam welding method for easily cracked materials according to claim 4, characterized in that, The ratio A is expressed as A = T0 / T m Where T0 is the heating temperature of the first stress control region, T m The melting point of the workpiece material; Welding Beam I b ′ Represented as I b ′ =I b0 ×(1-A), where, I b0 The welding beam current is an empirical value under normal temperature conditions, and the initial welding beam current range is (I b ′ -5) ~ I b ′ .

6. The electron beam welding method for easily cracked materials according to claim 1, characterized in that, The dynamic beam current adjustment method is as follows: starting from the weld start end, when the beam current travels along the welding direction to the interval of 1 / 2 to 3 / 4 of the weld length, the welding beam current is reduced by 5% to 15%.

7. The electron beam welding method for easily cracked materials according to claim 1, characterized in that, The width of the first stress control area is 10~50mm, and the distance between the edge of the second stress control area and the edge of the first stress control area is 10~50mm.

8. The electron beam welding method for easily cracked materials according to claim 1, characterized in that, The workpiece to be welded is an intermetallic compound or a high-temperature alloy.

9. The electron beam welding method for easily cracked materials according to any one of claims 1 to 8, characterized in that, Also includes: Design the allowance compensation value for the welded joint based on the given preheating welding allowance.

10. The electron beam welding method for easily cracked materials according to claim 9, characterized in that, When the welding allowance Δδ under normal temperature conditions is greater than or equal to the set value, the allowance compensation value is the preheating welding allowance; when the welding allowance Δδ under normal temperature conditions is less than the set value, the allowance compensation value is the sum of the welding allowance under normal temperature conditions and the preheating welding allowance.

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