CN100584507C - Composite control method of heat cycle for electron beam welding of TiAl intermetallic compounds - Google Patents

Abstract

TiAl intermetallic compound electron beam welding thermal cycle composite control method belongs to intermetallic compound jointing field.The invention solves the electron beam welding of TiAl intermetallic compound and be easy to generate macroscopical cold crack problem, can obtain the flawless joint.Method of the present invention is between welding object and welding machine anchor clamps thermal insulation board to be housed; Apply clamping force in two tabular welding object directions parallel then and fix, perhaps fix in the clamping force that axially applies of two tubulose welding objects with weld seam; Divide the thermal cycle of three phases programming continuous control whole welding process under vacuum condition, employing defocuses butt welded seam and carries out shuttle-scanning, preheating step by step; Weld immediately after the preheating; Adopt immediately after the welding and defocus butt welded seam and carry out shuttle-scanning after heat step by step.Welding control method process of the present invention is easy, need not increase equipment or fill transition material, is applicable to multiple joint type of attachment.

Description

Composite control method of heat cycle for electron beam welding of TiAl intermetallic compounds

technical field

The invention relates to a TiAl intermetallic compound electron beam welding method, belonging to the field of intermetallic compound welding.

Background technique

At present, a focus in engine research is to use new materials to replace traditional Ti alloys and Ni-based superalloys to increase the thrust-to-weight ratio of the engine and improve high-temperature performance. TiAl intermetallic compound has low density, high elastic modulus, and has good high-temperature strength, creep resistance and oxidation resistance. Compared with traditional superalloys, the service temperature of TiAl intermetallic compound can be increased to 750 ° C ~ 950 ° C , and the density is only half of that of Ni-based superalloys, it is a promising high-temperature structural material, which can be applied to high-temperature components of automobiles or aero-engines, such as blades, turbine discs, exhaust pipes and valves. For the application of TiAl intermetallic compounds in engineering practice, its connection technology must be successfully developed. Research results at home and abroad show that solid-state connections such as brazing, diffusion welding, friction welding, etc. are considered to be more effective connection technologies, but are often subject to The connection form and the use temperature are limited, and more lap joints are used to make the welding structure complicated and it is difficult to achieve light weight. Therefore, it is necessary to conduct in-depth research on the fusion welding of TiAl intermetallic compounds, especially the development of high-energy electron beam welding technology under vacuum conditions. However, the most prominent problems of TiAl intermetallic compounds are that γ-TiAl itself has few slip systems, difficulty in dislocation movement and proliferation, low room temperature plasticity and poor deformability. Although the microstructure and plasticity of this material can be improved by alloying or using different heat treatment processes, the rapid thermal cycle during electron beam welding makes the microstructure of the joint different from that of the base metal, and it is easy to cause large thermally induced stress. It leads to the easy formation of cold cracks in the joints, which restricts the application of the alloy in engineering practice. At present, there are no reports on the reasonable methods to solve this problem at home and abroad.

Contents of the invention

The purpose of the invention is to solve the problem that the electron beam welding of TiAl intermetallic compound is easy to produce macroscopic cold cracks.

TiAl intermetallic compound electron beam welding heat cycle composite control method, its welding object is two plates with a thickness of 0.8mm ~ 5.0mm, the specific steps are:

Step 1. Before fixing the two TiAl intermetallic compound plates whose internal stress has been removed and whose welding surface is smooth and clean, fix a heat shield between the welding fixture base and each welding object;

Step 2, clamping the welding object, the clamp only applies a clamping force in the direction parallel to the welding seam of the welding object;

Step 3. Under the atmospheric pressure of 5×10 ^-2 Pa to 5×10 ^-4 Pa, use defocus to scan back and forth on the part to be welded, and preheat in stages. The beam scans from one end of the weld to the other end, the accelerating voltage is 50kV~55kV, the focusing current is 3370mA, and the scanning speed is 2mm/s~10mm/s;

After step 4 and step 3 are completed, weld immediately, the acceleration voltage is the same as step 3, the focusing current is 2590mA, the beam current is 3mA-50mA, and the welding speed is 2mm/s-15mm/s;

After step 5 and step 4 are completed, defocusing is used to classify the weld immediately after heating, and each level uses 12mA ~ 1mA beam current in descending order to scan from one end of the weld to the other end, and the acceleration voltage Same as Step 3, the focusing current is 3370mA, and the scanning speed is 2mm/s-20mm/s.

TiAl intermetallic compound electron beam welding heat cycle compound control method, its welding object is two pipes of TiAl intermetallic compound with a wall thickness of 0.8mm to 3.5mm, and the welded seam is a circular weld seam. The specific steps are:

Step 1. Fix the heat shield between the fixture and the welding object before fixing the two welding objects whose internal stress has been removed and whose welding surface is to be smooth and clean;

Step 2, clamping the welding object, and the clamp adopts an axial clamping method for the welding object;

Step 3. Under the atmospheric pressure of 5×10 ^-2 Pa to 5×10 ^-4 Pa, use defocus to scan repeatedly and preheat the area to be welded in stages. The beam scans around the circular weld seam for one week; the accelerating voltage is 50kV~55kV, the focusing current is 3350mA, and the scanning speed is 2mm/s~8mm/s;

Step 4. Immediately weld after step 3 is completed. The acceleration voltage is the same as step 3. The focusing current is 2590mA, the beam current is 2mA~32mA, and the welding speed is 2mm/s~10mm/s;

After step 5 and step 4 are completed, immediately defocus the welded seam and heat it after classification. Each level uses 10mA-2mA beam currents that decrease in order from large to small to scan around the circular weld seam for a week, and the acceleration voltage Same as Step 3, the focusing current is 3350mA, and the scanning speed is 2mm/s～12mm/s.

When the welding objects are two plates with a thickness of 0.8mm to 2.0mm, the specific steps are:

Step 1. Before fixing the two TiAl intermetallic compound plates whose internal stress has been removed and whose welding surface is smooth and clean, fix a heat shield between the welding fixture base and each welding object;

Step 2, clamping the welding object, the clamp only applies a clamping force in the direction parallel to the welding object and the weld seam;

Step 3. Under the atmospheric pressure of 5×10 ^-2 Pa to 5×10 ^-4 Pa, use defocusing to scan the part to be welded back and forth, and preheat in two stages. Each stage uses 2mA beam current from one end of the weld Scanning to the other end, the accelerating voltage is 50kV~55kV, the focusing current is 3370mA, and the scanning speed is 2mm/s~10mm/s;

After step 4 and step 3 are completed, weld immediately, the acceleration voltage is the same as step 3, the focusing current is 2590mA, the beam current is 2mA~8mA, and the welding speed is 5mm/s~15mm/s;

After Step 5 and Step 4 are completed, immediately use defocusing to perform four-stage afterheating on the weld seam. Each stage uses 4mA, 4mA, 2mA, and 2mA beam current to scan from one end of the weld seam to the other end to accelerate the voltage and step. The three are the same, the focusing current is 3370mA, and the scanning speed is 2mm/s～20mm/s.

When the welding object is two TiAl intermetallic compound pipes with a wall thickness of 0.8mm to 1.5mm, the welded seam is a circular weld seam, and the specific steps are:

Step 1. Fix the heat shield between the fixture and the welding object before fixing the two welding objects whose internal stress has been removed and whose welding surface is to be smooth and clean;

Step 2, clamping the welding object, and the clamp adopts an axial clamping method for the welding object;

Step 3. Under the atmospheric pressure of 5×10 ^-2 Pa to 5×10 ^-4 Pa, use defocus to scan repeatedly and preheat the area to be welded, and use 2mA beam current to scan around the circular weld seam at each stage One week; the accelerating voltage is 50kV~55kV, the focusing current is 3350mA, and the scanning speed is 2mm/s~8mm/s;

Step 4. Immediately weld after step 3 is completed. The acceleration voltage is the same as step 3. The focusing current is 2590mA, the beam current is 2mA~8mA, and the welding speed is 2mm/s~10mm/s;

After step 5 and step 4 are completed, immediately defocus the welded seam for four-stage post-heating. Each stage uses 4mA, 2mA, 2mA, and 2mA beams to scan around the circular weld seam to accelerate the voltage and step. The three are the same, the focusing current is 3350mA, and the scanning speed is 2mm/s～12mm/s.

When the welding object is two TiAl intermetallic compound pipes with a wall thickness of 2.0mm to 3.5mm, the welded seam is a circular weld, and the specific steps are:

Step 1. Fix the heat shield between the fixture and the welding object before fixing the two welding objects whose internal stress has been removed and whose welding surface is to be smooth and clean;

Step 2, clamping the welding object, and the clamp adopts an axial clamping method for the welding object;

Step 3. Under the atmospheric pressure of 5×10 ^-2 Pa to 5×10 ^-4 Pa, use defocus to scan repeatedly the area to be welded, and preheat in four stages. Each stage uses 2mA, 2mA, 4mA, 6mA beams respectively. Flow around the annular weld and scan for one cycle; the acceleration voltage is 50kV~55kV, the focusing current is 3350mA, and the scanning speed is 2mm/s~8mm/s;

Step 4. Immediately weld after step 3 is completed. The acceleration voltage is the same as step 3. The focusing current is 2590mA, the beam current is 10mA~32mA, and the welding speed is 2mm/s~10mm/s;

After step 5 and step 4 are completed, immediately defocus the welded seam for six levels of afterheating. Each level uses 6mA, 5mA, 4mA, 3mA, 2mA, and 2mA beams to scan around the circular weld seam. The accelerating voltage is the same as step three, the focusing current is 3350mA, and the scanning speed is 2mm/s～12mm/s.

The composition of the TiAl intermetallic compound to be welded includes: Ti: 48-65 at.%, Al: 35-51 at.%, and V: 1.0-9.0 at.% or Cr: 1.5-2.5 at.% or Nb: 1.5-5.0 at.%, the sum of the percentages of various components of the TiAl intermetallic compound is 100%.

The thermal cycle compound control method for electron beam welding of TiAl intermetallic compounds of the present invention can completely avoid macroscopic cracks in the weld seam without adding special equipment or adding transition layer metal, and achieve the purpose of crack-free welding, which is suitable for TiAl intermetallic compounds Welding of various joint forms.

Detailed ways

Specific implementation mode 1: TiAl intermetallic compound electron beam welding thermal cycle compound control method, its welding object is two plates with a thickness of 0.8 mm to 5.0 mm, and the specific steps are:

Step 1. Before fixing the two TiAl intermetallic compound plates whose internal stress has been removed and whose welding surface is smooth and clean, fix a heat shield between the welding fixture base and each welding object;

Step 2, clamping the welding object, the clamp only applies a clamping force in the direction parallel to the welding object and the weld seam;

Step 3. Under the atmospheric pressure of 5×10 ^-2 Pa to 5×10 ^-4 Pa, use defocus to scan back and forth on the part to be welded, and preheat in stages. The beam scans from one end of the weld to the other end, the accelerating voltage is 50kV~55kV, the focusing current is 3370mA, and the scanning speed is 2mm/s~10mm/s;

After step 4 and step 3 are completed, weld immediately, the acceleration voltage is the same as step 3, the focusing current is 2590mA, the beam current is 3mA-50mA, and the welding speed is 2mm/s-15mm/s;

After step 5 and step 4 are completed, defocusing is used to classify the weld immediately after heating, and each level uses 12mA ~ 1mA beam current in descending order to scan from one end of the weld to the other end, and the acceleration voltage Same as Step 3, the focusing current is 3370mA, and the scanning speed is 2mm/s-20mm/s.

The composition of the TiAl intermetallic compound described in this embodiment includes: Ti: 48-65 at.%, Al: 35-51 at.%, and may also include V: 1.0-9.0 at.% or Cr: 1.5-2.5 at.%. Or Nb: 1.5 to 5.0 at.%.

In step 1 of this embodiment, a heat shield is added between the welding object and the fixture base to limit the heat conduction between the welding object and the fixture, which can effectively reduce the cooling speed of the welded joint.

In step 2 of this embodiment, the welding object is clamped only by applying a clamping force in the direction parallel to the weld seam, so as to restrain the thermal expansion of the welding object along the direction of the weld seam during the thermal cycle heating stage, and reduce the temperature of the welding object during thermal cycle cooling. The thermally induced stress generated in the thermal cycle stage, while no restraint is applied in other directions, effectively avoids the large restraint stress generated in the cooling stage of the thermal cycle, and has a certain effect on preventing the generation of macroscopic cracks.

In this embodiment, from steps 3 to 5, the thermal cycle of the entire welding process is continuously controlled by programming in three stages. In the preheating process of step 3, graded preheating is adopted, and the beam current is increased step by step, so that the temperature of the surrounding parts of the weld can be increased. Gradually increase, in step five post-heating process after welding, adopt graded post-heating, gradually reduce the beam current, can make the temperature of the weld seam after welding and its surroundings drop gradually. Taking these methods can improve the structure of the joint, prolong the stress release time, and obtain an electron beam welded joint without macroscopic cold cracks.

Specific embodiment 2: The thickness of the welding object in this embodiment is 2.0 mm to 3.0 mm. The difference between the welding method and specific embodiment 1 is that

In the preheating process of step 3, four stages of preheating are used, and each stage uses beam currents of 2mA, 4mA, 6mA and 8mA to scan from one end of the weld to the other end;

In step 4, welding is performed with a beam current of 16mA-32mA and a welding speed of 5mm/s-10mm/s;

In the post-heating process of step five, four stages of post-heating are used, and each stage adopts beam currents of 8mA, 6mA, 4mA, and 2mA to scan from one end of the weld to the other end.

Embodiment 3: The difference between this embodiment and Embodiment 1 is that the thickness of the object to be welded is 0.8 mm to 2.0 mm. The difference between the welding method and Embodiment 1 is that

In the preheating process of step 3, two stages of preheating are used, and each stage uses a 2mA beam current to scan from one end of the weld to the other end;

In step 4, the welding part is welded with a beam current of 2mA-8mA and a welding speed of 5mm/s-15mm/s;

In the post-heating process of step five, four stages of post-heating are used, and each stage adopts beam currents of 4mA, 4mA, 2mA, and 2mA to scan from one end of the weld to the other end.

Embodiment 4: The difference between this embodiment and Embodiment 1 is that the thickness of the object to be welded is 3.0 mm to 5.0 mm. The difference between the welding method and Embodiment 1 is that

In the preheating process of step 3, six levels of preheating are used, and each level uses beam currents of 2mA, 4mA, 6mA, 8mA, 9mA, and 10mA to scan from one end of the weld to the other end;

In step 4, the welding part is welded with a beam current of 24mA-50mA, and the welding speed is 2mm/s-10mm/s;

In the post-heating process of step five, six levels of post-heating are used, and each level uses beam currents of 10mA, 9mA, 8mA, 6mA, 4mA, and 2mA to scan from one end of the weld to the other end.

Embodiment 5: The material composition of the insulation board described in Step 1 of Embodiment 1 is silicon dioxide and silicate.

The heat insulation board of this embodiment has a good heat insulation effect, and can effectively prevent the heat generated by welding on the object to be welded from being transferred to the base of the welding fixture. On the one hand, it reduces energy loss, and on the other hand, it also prevents the Heat conduction from the base of the fixture results in an increased joint cooling rate.

Embodiment 6: The difference between this embodiment and Embodiments 1 to 5 is that after step 5 is completed, step 6, the process of stress relief annealing is carried out, and the welding object is heated to 900 ° C, kept for 10 hours, and then cooled with the furnace.

Embodiment 7: TiAl intermetallic compound electron beam welding thermal cycle composite control method, its welding object is two pipes of TiAl intermetallic compound with a wall thickness of 0.8 mm to 3.5 mm, and the welded seam is a circular weld seam. The specific steps are:

Step 1. Fix the heat shield between the fixture and the welding object before fixing the two welding objects whose internal stress has been removed and whose welding surface is to be smooth and clean;

Step 2, clamping the welding object, and the clamp adopts an axial clamping method for the welding object;

Step 3. Under the atmospheric pressure of 5×10 ^-2 Pa to 5×10 ^-4 Pa, use defocus to scan repeatedly and preheat the area to be welded in stages. The beam scans around the circular weld seam for one week; the accelerating voltage is 50kV~55kV, the focusing current is 3350mA, and the scanning speed is 2mm/s~8mm/s;

Step 4. Immediately weld after step 3 is completed. The acceleration voltage is the same as step 3. The focusing current is 2590mA, the beam current is 2mA~32mA, and the welding speed is 2mm/s~10mm/s;

After step 5 and step 4 are completed, immediately defocus the welded seam and heat it after classification. Each level uses 10mA-2mA beam currents that decrease in order from large to small to scan around the circular weld seam for a week, and the acceleration voltage Same as Step 3, the focusing current is 3350mA, and the scanning speed is 2mm/s～12mm/s.

The composition of the TiAl intermetallic compound described in this embodiment includes: Ti: 48-65 at.%, Al: 35-51 at.%, and may also include V: 1.0-9.0 at.% or Cr: 1.5-2.5 at.%. Or Nb: 1.5 to 5.0 at.%.

In step 1 of this embodiment, a heat shield is fixed between the fixture and the welding object to limit the heat conduction between the welding object and the fixture, and reduce the cooling speed of the welded joint.

In the second step of this embodiment, the tightening force is only applied in the axial direction of the welding object, so as to avoid the large restraint stress generated in the thermal cycle cooling stage.

In this embodiment, the thermal cycle of the entire welding process is continuously controlled by programming in three stages from steps 3 to 5, so that the temperature of the weld seam and its surroundings is always in a slow transition state, effectively preventing the occurrence of thermal shocks around the weld seam due to sudden temperature changes. The case of macro-cracks.

Embodiment 8: The pipe wall thickness of the welding object in this embodiment is 0.8 mm to 1.5 mm. The difference from the method described in Embodiment 7 is that

In the preheating process of step 3, two stages of preheating are used, and each stage uses a 2mA beam to scan around the circular weld seam for one week;

In step 4, welding is performed with a beam current of 2mA-8mA;

In the post-heating process of Step 5, four stages of post-heating are used, and beam currents of 4mA, 2mA, 2mA, and 2mA are respectively used in each stage to scan around the circular weld seam for one circle.

Specific embodiment nine: the thickness of the pipe wall of the welding object in this embodiment is 2.0 mm to 3.5 mm, and the difference from the method described in specific embodiment seven is that,

In the preheating process of step 3, four stages of preheating are used, and each stage uses 2mA, 2mA, 4mA, and 6mA beams to scan around the circular weld for one week;

In step 4, welding is performed with a beam current of 10mA-32mA;

In the post-heating process of step five, six levels of post-heating are used, and beam currents of 6mA, 5mA, 4mA, 3mA, 2mA, and 2mA are used for each level to scan around the annular weld seam for one circle.

Embodiment 10: In Embodiments 7 to 9, after step 5, add step 6, stress relief annealing process, heating the welding object to 900°C, keeping it warm for 10 hours, and then cooling with the furnace.

Claims (8)

1, TiAl intermetallic compound electron beam welding thermal cycle composite control method, its welding object is two plate objects that thickness is 0.8mm～5.0mm, it is characterized in that concrete steps are:

Step 1, will remove internal stress, the smooth cleaning of surface to be welded the sheet material of two TiAl intermetallic compounds with anchor clamps fixing before, between welding machine clamp base and each welding object, fix a thermal insulation board respectively;

Step 2, welding object implement is clamped, described anchor clamps only apply clamping force in the welding object direction parallel with weld seam;

Step 3,5 * 10 ^-2Pa to 5 * 10 ^-4Under the atmospheric pressure of Pa, employing defocuses carries out shuttle-scanning, classification preheating to place to be welded, each grade adopts the line that increases progressively successively from small to large among 2mA～12mA to scan the other end from an end of weld seam respectively, accelerating potential is 50kV～55kV, focus current 3370mA, sweep speed is 2mm/s～10mm/s;

Step 4, step 3 are welded after finishing immediately, and accelerating potential is identical with step 3, and focus current is 2590mA, and line is 3mA～50mA, and speed of welding is 2mm/s～15mm/s;

After step 5, step 4 are finished, employing immediately defocuses butt welded seam and carries out the classification after heat, each grade adopts the line that successively decreases successively from big to small among 12mA～1mA to scan the other end from an end of weld seam respectively, accelerating potential is identical with step 3, focus current is 3370mA, and sweep speed is 2mm/s～20mm/s;

The composition of described TiAl intermetallic compound comprises: Ti:48～65at.%, Al:35～51at.%, also comprise V:1.0～9.0at.% or Cr:1.5～2.5at.% or Nb:1.5～5.0at.%, the percentage sum of the various compositions of described TiAl intermetallic compound is 100%.

2, TiAl intermetallic compound electron beam welding thermal cycle composite control method according to claim 1, the material composition that it is characterized in that described thermal insulation board is silica and silicate.

3, TiAl intermetallic compound electron beam welding thermal cycle composite control method according to claim 1, the thickness that it is characterized in that welding object is 2.0mm～3.0mm, welding method is:

In the warm of step 3, adopt the level Four preheating, every grade of line that adopts 2mA, 4mA, 6mA and 8mA respectively scans the other end from an end of weld seam;

In step 4, adopt the line of 16mA～32mA, the speed of welding of 5mm/s～10mm/s to weld;

In the back thermal process of step 5, adopt the level Four after heat, every grade of line that adopts 8mA, 6mA, 4mA, 2mA respectively scans the other end from an end of weld seam.

4, TiAl intermetallic compound electron beam welding thermal cycle composite control method according to claim 1, the thickness that it is characterized in that institute's welding object is 3.0mm～5.0mm, welding method is:

In the warm of step 3, adopt six grades of preheatings, every grade of line that adopts 2mA, 4mA, 6mA, 8mA, 9mA, 10mA respectively scans the other end from an end of weld seam;

In step 4, adopt the line of 24mA～50mA that the welding position is welded, speed of welding is 2mm/s～10mm/s;

In the back thermal process of step 5, adopt six grades of after heat, every grade of line that adopts 10mA, 9mA, 8mA, 6mA, 4mA, 2mA respectively scans the other end from an end of weld seam.

5, TiAl intermetallic compound electron beam welding thermal cycle composite control method, its welding object is two plate objects that thickness is 0.8mm～2.0mm, it is characterized in that concrete steps are:

Step 1, will remove internal stress, the smooth cleaning of surface to be welded the sheet material of two TiAl intermetallic compounds with anchor clamps fixing before, between welding machine clamp base and each welding object, fix a thermal insulation board respectively;

Step 2, welding object implement is clamped, described anchor clamps only apply clamping force in the welding object direction parallel with weld seam;

Step 3,5 * 10 ^-2Pa to 5 * 10 ^-4Under the atmospheric pressure of Pa, employing defocuses carries out shuttle-scanning, two-stage preheating to place to be welded, and the line that each grade adopts 2mA respectively scans the other end from an end of weld seam, and accelerating potential is 50kV～55kV, focus current 3370mA, sweep speed is 2mm/s～10mm/s;

Step 4, step 3 are welded after finishing immediately, and accelerating potential is identical with step 3, and focus current is 2590mA, and line is 2mA～8mA, and speed of welding is 5mm/s～15mm/s;

After step 5, step 4 are finished, employing immediately defocuses butt welded seam and carries out the level Four after heat, the line that each grade adopts 4mA, 4mA, 2mA, 2mA respectively scans the other end from an end of weld seam, accelerating potential is identical with step 3, focus current is 3370mA, and sweep speed is 2mm/s～20mm/s;

The composition of described TiAl intermetallic compound comprises: Ti:48～65at.%, Al:35～51at.%, also comprise V:1.0～9.0at.% or Cr:1.5～2.5at.% or Nb:1.5～5.0at.%, the percentage sum of the various compositions of described TiAl intermetallic compound is 100%.

6, TiAl intermetallic compound electron beam welding thermal cycle composite control method, its welding object are that two root canal wall thickness are the tubing of the TiAl intermetallic compound of 0.8mm～3.5mm, and the weld seam of welding is a circular weld, it is characterized in that concrete steps are:

Step 1, will remove internal stress, the smooth cleaning of surface to be welded two welding objects with anchor clamps fixing before, fixing thermal insulation board between anchor clamps and welding object;

Step 2, welding object implement is clamped, described anchor clamps adopt the mode that axially clamps to welding object;

Step 3,5 * 10 ^-2Pa to 5 * 10 ^-4Under the atmospheric pressure of Pa, adopt to defocus place to be welded is carried out multiple scanning, classification preheating, each grade adopts the line that increases progressively successively from small to large among 2mA～10mA around the circular weld run-down respectively; Accelerating potential is 50kV～55kV, focus current 3350mA, and sweep speed is 2mm/s～8mm/s;

Step 4, step 3 are welded after finishing immediately, and accelerating potential is identical with step 3, and focus current is 2590mA, and line is 2mA～32mA, and speed of welding is 2mm/s～10mm/s;

After step 5, step 4 are finished, the weld seam that welding is finished adopts to defocus and carries out the classification after heat immediately, each grade adopts the line that successively decreases successively from big to small among 10mA～2mA around the circular weld run-down respectively, accelerating potential is identical with step 3, focus current is 3350mA, sweep speed is 2mm/s～12mm/s

The composition of described TiAl intermetallic compound comprises: Ti:48～65at.%, Al:35～51at.%, also comprise V:1.0～9.0at.% or Cr:1.5～2.5at.% or Nb:1.5～5.0at.%, the percentage sum of the various compositions of described TiAl intermetallic compound is 100%.

7, TiAl intermetallic compound electron beam welding thermal cycle composite control method, its welding object are that two root canal wall thickness are the tubing of the TiAl intermetallic compound of 0.8mm～1.5mm, and the weld seam of welding is a circular weld, it is characterized in that concrete steps are:

Step 1, will remove internal stress, the smooth cleaning of surface to be welded two welding objects with anchor clamps fixing before, fixing thermal insulation board between anchor clamps and welding object;

Step 2, welding object implement is clamped, described anchor clamps adopt the mode that axially clamps to welding object;

Step 3,5 * 10 ^-2Pa to 5 * 10 ^-4Under the atmospheric pressure of Pa, adopt to defocus place to be welded is carried out multiple scanning, secondary preheating, each grade adopts the line of 2mA around the circular weld run-down respectively; Accelerating potential is 50kV～55kV, focus current 3350mA, and sweep speed is 2mm/s～8mm/s;

Step 4, step 3 are welded after finishing immediately, and accelerating potential is identical with step 3, and focus current is 2590mA, and line is 2mA～8mA, and speed of welding is 2mm/s～10mm/s;

After step 5, step 4 are finished, the weld seam that welding is finished adopts to defocus and carries out the level Four after heat immediately, each grade adopts the line of 4mA, 2mA, 2mA, 2mA around the circular weld run-down respectively, accelerating potential is identical with step 3, focus current is 3350mA, sweep speed is 2mm/s～12mm/s

The composition of described TiAl intermetallic compound comprises: Ti:48～65at.%, Al:35～51at.%, also comprise V:1.0～9.0at.% or Cr:1.5～2.5at.% or Nb:1.5～5.0at.%, the percentage sum of the various compositions of described TiAl intermetallic compound is 100%.

8, TiAl intermetallic compound electron beam welding thermal cycle composite control method, its welding object are that two root canal wall thickness are the tubing of the TiAl intermetallic compound of 2.0mm～3.5mm, and the weld seam of welding is a circular weld, it is characterized in that concrete steps are:

Step 1, will remove internal stress, the smooth cleaning of surface to be welded two welding objects with anchor clamps fixing before, fixing thermal insulation board between anchor clamps and welding object;

Step 2, welding object implement is clamped, described anchor clamps adopt the mode that axially clamps to welding object;

Step 3,5 * 10 ^-2Pa to 5 * 10 ^-4Under the atmospheric pressure of Pa, adopt to defocus place to be welded is carried out multiple scanning, level Four preheating, each grade adopts the line of 2mA, 2mA, 4mA, 6mA around the circular weld run-down respectively; Accelerating potential is 50kV～55kV, focus current 3350mA, and sweep speed is 2mm/s～8mm/s;

Step 4, step 3 are welded after finishing immediately, and accelerating potential is identical with step 3, and focus current is 2590mA, and line is 10mA～32mA, and speed of welding is 2mm/s～10mm/s;

After step 5, step 4 are finished, the weld seam that welding is finished adopts to defocus and carries out six grades of after heat immediately, each grade adopts the line of 6mA, 5mA, 4mA, 3mA, 2mA, 2mA around the circular weld run-down respectively, accelerating potential is identical with step 3, focus current is 3350mA, sweep speed is 2mm/s～12mm/s

The composition of described TiAl intermetallic compound comprises: Ti:48～65at.%, Al:35～51at.%, also comprise V:1.0～9.0at.% or Cr:1.5～2.5at.% or Nb:1.5～5.0at.%, the percentage sum of the various compositions of described TiAl intermetallic compound is 100%.