CN111299833A - Dissimilar metal pulse laser welding method for titanium alloy and stainless steel - Google Patents
Dissimilar metal pulse laser welding method for titanium alloy and stainless steel Download PDFInfo
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- CN111299833A CN111299833A CN202010158717.4A CN202010158717A CN111299833A CN 111299833 A CN111299833 A CN 111299833A CN 202010158717 A CN202010158717 A CN 202010158717A CN 111299833 A CN111299833 A CN 111299833A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/20—Bonding
- B23K26/21—Bonding by welding
- B23K26/24—Seam welding
- B23K26/26—Seam welding of rectilinear seams
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/60—Preliminary treatment
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K2103/00—Materials to be soldered, welded or cut
- B23K2103/18—Dissimilar materials
- B23K2103/24—Ferrous alloys and titanium or alloys thereof
Abstract
The invention discloses a dissimilar metal pulse laser welding method of titanium alloy and stainless steel, belonging to the technical field of dissimilar metal welding, wherein the welding process mainly comprises the following steps: firstly, cleaning the surfaces to be welded of titanium alloy and stainless steel; then, the titanium alloy, the stainless steel, the copper foil and the niobium foil are butted and placed according to a certain sequence; finally, pulse laser welding is adopted to weld the sample, a Cu/Nb composite interlayer is selected as a transition layer between the base materials, a niobium-based solid solution can be formed on one side of the titanium alloy and a copper-iron solid solution is formed on one side of the stainless steel by adjusting parameters such as laser power, pulse width, frequency, welding speed, interlayer thickness and the like, so that mutual diffusion and reaction of titanium atoms and iron elements are effectively inhibited, and TiFe are avoided2Iso-brittle intermetallic formationFormation of a compound; the welding joint obtained by the method has the advantages of few welding defects, excellent mechanical property of the joint and the like.
Description
Technical Field
The invention relates to the technical field of dissimilar metal welding, in particular to a pulse laser welding method for dissimilar metals of titanium alloy and stainless steel.
Background
The AISI 316L stainless steel is a structural material with excellent corrosion resistance, reliability, high strength and low cost, has excellent processing performance and welding performance, and is widely applied to various industrial fields. The titanium alloy has excellent performances of high specific strength, high corrosion resistance, low density and the like, and is widely applied to the industries of aerospace, nuclear, chemical industry and the like.
When the satellite performs detection work, the infrared focal plane detector is the main equipment, and the miniature Dewar is the packaging and protecting device of the infrared focal plane detector, so that good optical, mechanical, electrical and heat transmission channels are provided for the infrared focal plane detector during low-temperature work. Currently, the preferred materials for manufacturing metal dewars are stainless steel and titanium alloys. However, welding between titanium alloy and stainless steel is more problematic, mainly because of the differences in physical and chemical properties (such as expansion coefficient, specific heat capacity, thermal conductivity, melting point, chemical composition, etc.) of the two metal materials, which results in the formation of large residual stresses in the welded joint.
Meanwhile, according to the material characteristics and the ferrotitanium binary phase diagram, FeTi and Fe are easily generated in a weld pool in the welding process of titanium alloy and stainless steel2A brittle intermetallic compound containing Ti as a main component. Therefore, in order to improve the quality of the welded joint, a copper-niobium composite interlayer is added between the stainless steel and the titanium alloy to inhibit the formation of brittle ferrotitanium phases. According to the Ti-Nb phase diagram, a continuous solid solution is formed in the melt pool between Ti and Nb. According to the Cu-Nb phase diagram, a continuous solid solution is also formed between Cu and Nb. In addition, the reaction of copper and stainless steel does not produce intermetallic compounds. Therefore, in the instant weldingIn the bonding method, a Cu/Nb composite interlayer is used to suppress the formation of a brittle ferrotitanium phase.
In 2018, a domestic scholars published an article named as 'influence of an electroplating barrier layer on the performance of a titanium/steel electron beam welded joint' on rare metal materials and engineering journals. The titanium alloy and the stainless steel are welded by adopting electron beam fusion welding, electron beam barrier welding and electron beam barrier fusion-brazing. It was found that brittle intermetallic compounds were generated in the weld, which was not favorable for the improvement of the weld quality. When welding is performed by direct fusion welding and barrier fusion welding, direct fracture of the joint is caused by the generation of through cracks. Therefore, the performance of the weld joint still needs to be further improved.
The chinese patent application CN103192195A discloses an electron beam welding method for titanium alloy and stainless steel. The method adopts a vanadium layer and a copper-chromium alloy layer as interlayers for welding, and mainly cuts a copper-chromium alloy plate and a vanadium cast ingot into a proper thickness as a filling layer. And simultaneously performing electron beam welding by adopting double welding. Although the welding method realizes effective connection of the titanium alloy and the stainless steel, the steps are complicated due to the limitation on the size of the workpiece, and the limiting factors such as large welding residual stress and the like are easily generated in a welding seam.
Disclosure of Invention
The invention aims to solve the problem of poor welding performance between titanium alloy and stainless steel in the prior art, and provides a pulse laser welding method for dissimilar metals between titanium alloy and stainless steel.
In order to achieve the purpose of the invention, the technical scheme provided by the invention is as follows:
a dissimilar metal pulse laser welding method for titanium alloy and stainless steel comprises the following specific steps:
(1) cleaning the surface of a welding sample: cleaning surfaces to be welded of titanium alloy and stainless steel, copper foil and niobium foil to obtain a welding sample with a clean surface; the thickness of the copper foil is 400-450 mu m, and the thickness of the niobium foil is 350-400 mu m;
(2) placing a welding sample: sequentially butting and placing the titanium alloy, the stainless steel, the copper foil and the niobium foil after surface cleaning; the sequence is as follows: titanium alloy-niobium foil-copper foil-stainless steel, or stainless steel-copper foil-niobium foil-titanium alloy;
(3) welding: the welding is two welding, which respectively comprises the following steps:
first welding: aligning a laser beam to the middle position of the copper foil interlayer for welding, wherein the process parameters are as follows: the pulse frequency is 15-20Hz, the welding speed is 1-3m/s, the overlapping rate is 50-80%, the pulse width is 5-9ms, and the power is 1.5-3.5kW
And (3) second welding: and (3) aligning a laser beam to the middle position of the interlayer of the niobium foil for welding, wherein the process parameters are as follows: the pulse frequency is 15-20Hz, the welding speed is 1-3m/s, the overlapping rate is 50-80%, the pulse width is 5-9ms, and the power is 1.5-3.5 kW.
The inventor of the application starts with the thickness of the copper foil and the niobium foil of the intermediate interlayer through a large number of tests, simultaneously adopts two welding processes and optimizes the welding process, particularly the optimization of the overlapping rate, obtains unexpected technical effects through the mutual cooperation of the improved factors, obviously improves the quality of the welding joint of the titanium alloy and the stainless steel, and can enable the tensile strength of the welding joint of the titanium alloy and the stainless steel to reach more than 300MPa by adopting a pulse laser welding method.
Firstly, the welding method of the titanium alloy and the stainless steel realizes the matching of dissimilar materials by adopting the copper-niobium composite interlayer, and then adopts laser welding and a specific welding process to weld, so that the diffusion of harmful elements in a weld joint is inhibited, and the formation of brittle intermetallic compounds is avoided;
in the welding process, two welding steps are adopted for welding, so that the fusion welding between the copper foil and the stainless steel and the fusion welding between the niobium foil and the titanium alloy can be respectively realized, and the structure of a welding line can be effectively controlled;
then, the thickness of the composite interlayer also has a great effect on the regulation and control of welding quality, solid solutions with proper content ranges can be generated in a molten pool at a copper-stainless steel interface, a copper-niobium interface and a niobium-titanium alloy interface by adopting reasonable interlayer thickness, meanwhile, an unmelted interlayer also exists, and thus, the diffusion and reaction of iron and titanium can be effectively prevented, which is a necessary condition for obtaining a titanium alloy and stainless steel welding joint with higher strength.
Compared with other welding techniques, the method is simpler and more efficient in process, and the shape and the size of the adopted welding sample are easy to machine, so that the welding method can be successfully applied to the welding of the titanium alloy (preferably TC4 titanium alloy) and the stainless steel (preferably AISI 316L stainless steel).
Further, in the step (1), the purities of the copper foil and the niobium foil are both more than 98 wt%.
More preferably, the purity of the copper foil and niobium foil is greater than 99.9 wt%.
More preferably, the copper foil has a thickness of 430 μm and the niobium foil has a thickness of 380 μm.
Further, in the step (1), the surface of the welding sample is sequentially subjected to grinding, polishing, acid washing, oil removal and cleaning.
Preferably, the sanding and polishing process is as follows: selecting titanium alloy and stainless steel surfaces to be welded, then grinding by using sand paper, and then polishing. More preferably, it is necessary to have a surface roughness Ra of 1.0 μm or less, which facilitates the contact between the surfaces of the material to be welded.
Preferably, the surfaces to be welded of the titanium alloy and the surface of the copper foil are pickled. Since the oxide film generated on the surface of the titanium alloy and the copper foil is not favorable for the diffusion of atoms during welding, and the presence of oxygen atoms causes the formation of oxides in the weld bead to impair the welding quality, pickling is performed. More preferably, the mixed solution of hydrofluoric acid and nitric acid is adopted to treat the oxide film on the surface of the titanium alloy; by dilute H2SO4The solution is used for treating the oxide film on the surface of the copper foil.
Preferably, degreasing and cleaning are performed on the surfaces to be welded of titanium alloys and stainless steel and the surfaces of copper and niobium foils. The oil stain is removed because the oil stain is not favorable for the combination of interfaces and simultaneously impurities are introduced into welding seams, thereby damaging the welding quality. More preferably, acetone is selected for removing oil stains, and specifically, all samples are put into acetone and subjected to ultrasonic cleaning for 10-15 min. Then cleaning the surfaces to be welded of the titanium alloy and the stainless steel and the surfaces of the copper foil and the niobium foil by alcohol, and finally drying by cold air.
Further, in step (2), all the welding samples are rigidly fixed in the fixture with the forming groove after being placed in a butt joint mode.
Further, in the step (3), the gap between the materials is required to be less than or equal to 0.1 mm.
Preferably, the first welding: the pulse frequency is 16-18Hz, the welding speed is 1.5-2.5m/s, the overlapping rate is 60-80%, the pulse width is 6-9ms, and the power is 2-3.5 kW; and (3) second welding: the pulse frequency is 16-18Hz, the welding speed is 1.5-2.5m/s, the overlapping rate is 60-80%, the pulse width is 6-9ms, and the power is 2-3.5 kW.
For different positions of a welding seam, the selection of welding parameters is required to be carried out according to the characteristics of metal materials, so that the welding effect can be regulated and controlled to achieve better welding quality.
As an optimal technical scheme, copper foil and niobium foil are used as an intermediate interlayer, the laser power is 3kW, the pulse width is 8ms, the welding speed is 2mm/s, and the overlapping rate of welding spots is 70%.
The method is particularly suitable for welding the TC4 titanium alloy and the 316L stainless steel.
Compared with the prior art, the new technical scheme provided by the invention can mainly realize the following technical effects:
(1) the welding method of the titanium alloy and the stainless steel is carried out by adopting pulse laser welding, so that the interface combination among materials is promoted, and the macroscopic deformation of a sample is effectively prevented;
(2) according to the method, the copper-niobium composite interlayer is adopted, so that the stress between interfaces is relieved from the physical property, solid solutions are formed between the titanium alloy and the niobium foil, between the copper foil and the niobium foil and between the copper foil and the stainless steel from the chemical composition, the formation of brittle phases is well inhibited, and the quality of welding seams is improved;
(3) the welding method has the advantages of rapid heating and rapid cooling by means of laser welding, thereby promoting the refinement of crystal grains and the reduction of a heat affected zone and improving the mechanical property of a welding joint;
(4) compared with other welding methods, the welding method has the characteristics of simple and efficient welding process and less requirements on the shape and the size of a welding sample, so that the welding method can be successfully applied to the welding of titanium alloy and stainless steel.
Drawings
FIG. 1 is a schematic view of a copper niobium composite interlayer of the present invention;
FIG. 2 is a schematic illustration of laser welding in the present invention;
FIG. 3 is a microstructure of a weld zone in example 3, in which the microstructure of the side-melted region of the titanium alloy is mainly composed of a solid solution;
the labels in the figure are: 1 is AISI 316L stainless steel, 2 is the copper foil, 3 is the niobium foil, 4 is TC4 titanium alloy, 5 is first pulse laser, 6 is the second pulse laser.
Detailed Description
The present invention will be described in further detail with reference to test examples and specific embodiments. It should be understood that the scope of the above-described subject matter is not limited to the following examples, and any techniques implemented based on the disclosure of the present invention are within the scope of the present invention.
All materials involved in the embodiment of the invention are provided by Shanghai technical physics of Chinese academy of sciences.
The stainless steel of the following examples is illustrated by AISI 316L stainless steel, and the titanium alloy is illustrated by TC4 titanium alloy, and those skilled in the art will understand that the method of the present invention is equally applicable to other types of titanium alloys and stainless steel; the purities of the copper foil and the niobium foil are both more than 98 wt%.
Example 1
Grinding and polishing the surfaces to be welded of the TC4 titanium alloy and the AISI 316L stainless steel to ensure that the surface roughness Ra is less than or equal to 1.0 mu m; then removing an oxide film on the surface of the titanium alloy by adopting a mixed solution of hydrofluoric acid and nitric acid;and using dilute H2SO4The solution removes the oxide film on the surface of the copper foil. Then, degreasing and decontaminating the sample, putting all the samples into acetone for ultrasonic cleaning for 15min, wiping the to-be-welded surface of the sample with alcohol, and blow-drying with cold air to finally obtain clean titanium alloy, stainless steel, copper foil and niobium foil;
the above cleaning methods are all known in the art;
and sequentially butting and placing the processed titanium alloy, stainless steel, copper foil and niobium foil according to the sequence of titanium alloy-niobium foil-copper foil-stainless steel. Specifically, as shown in fig. 1, AISI 316L stainless steel 1, copper foil 2, niobium foil 3, TC4 titanium alloy 4 were arranged in sequence and rigidly fixed in a jig with a forming groove to ensure that the gap between the materials was less than 0.1 mm.
And then, placing the assembled sample into a vacuum chamber of a laser welding machine, setting welding parameters, and welding according to a standard flow. First welding: the pulse frequency is 18Hz, the welding speed is 2m/s, the overlapping rate is 70 percent, the pulse width is 9ms, and the power is 2 kW; and (3) second welding: the pulse frequency was 18Hz, the welding speed was 2m/s, the overlap rate was 70%, the pulse width was 9ms, and the power was 2 kW. The thickness of the selected copper foil is 430 μm, and the thickness of the selected niobium foil is 380 μm; welding by adopting a laser welding machine in the following sequence: welding the middle position of the copper foil interlayer; and then welding the middle of the interlayer of the niobium foil.
Specifically, as shown in fig. 2, the first pulse laser 5 is directly opposite to the middle position of the copper foil 2; the second pulse laser 6 is opposite to the middle position of the niobium foil 3. And after welding, waiting for the sample to be cooled, opening a vacuum chamber of a welding machine to take out the sample, and finally obtaining the welding sample of the TC4 titanium alloy and the AISI 316L stainless steel.
Example 2
The same welding process as in example 1 was used to weld the titanium alloy and stainless steel. The conditions were the same as in example 1, except that the laser power was 2.5 kW.
Example 3
The same welding process as in example 1 was used to weld the titanium alloy and stainless steel. The conditions were the same as in example 1, except that the laser power was 3 kW.
The microstructure of the weld zone in the present example is shown in fig. 3, and it can be seen from fig. 3 that the microstructure of the side fusion zone of the titanium alloy is mainly composed of solid solution.
Example 4
The same welding process as in example 1 was used to weld the titanium alloy and stainless steel. The conditions were the same as in example 1, except that the laser power was 3.5 kW.
The effect of different laser powers on pulsed laser welding of titanium alloys to stainless steel was compared and the results are given in table 1 below.
The invention is regulated according to the national standard GB/T228-2002, and the tensile test is carried out on the welding sample at room temperature, and the loading rate is 0.5 mm/min. And observing the tensile fracture by using a scanning electron microscope, and judging the fracture property according to the existence of the characteristics of the tough pits, the river flower shape and the like.
TABLE 1 mechanical Properties of titanium alloy/stainless Steel Metal welded parts
The test results in table 1 show that the magnitude of the pulse laser welding power has a great influence on the tensile strength of the welded joint when the stainless steel and titanium alloy welding scheme of the invention is adopted for welding. With lower laser power, the diffusion of elements is insufficient due to insufficient melting of the material, thereby reducing the welding strength. As power is increased, the performance of the joint is gradually improved due to the increased amount of metal melted in the weld. Then, when the power is too high, the harmful brittle phase is generated due to the accumulation and reaction of harmful elements in the weld fusion zone caused by too large energy input, thereby degrading the joint performance. Therefore, the power of laser welding is preferably 3 kW.
Example 5
Grinding and polishing the surfaces to be welded of the TC4 titanium alloy and the AISI 316L stainless steel to ensure that the surface roughness Ra is less than or equal to 1.0 mu m; then removing an oxide film on the surface of the titanium alloy by adopting a mixed solution of hydrofluoric acid and nitric acid; and using dilute H2SO4The solution removes the oxide film on the surface of the copper foil. And then, degreasing and decontaminating the samples, putting all the samples into acetone for ultrasonic cleaning for 15min, wiping the surfaces to be welded of the samples with alcohol, and blow-drying with cold air to finally obtain clean titanium alloy, stainless steel, copper foil and niobium foil.
The processed titanium alloy, stainless steel, copper foil and niobium foil are sequentially placed in a butt joint mode according to the sequence of titanium alloy-niobium foil-copper foil-stainless steel, and are rigidly fixed in a clamp with a forming groove, so that the gap between the materials is ensured to be smaller than 0.1 mm.
And then, placing the assembled sample into a vacuum chamber of a laser welding machine, setting welding parameters, and welding according to a standard flow. First welding: the pulse frequency is 17Hz, the welding speed is 2m/s, the overlapping rate is 70%, the pulse width is 8ms, and the power is 3 kW; and (3) second welding: the pulse frequency was 17Hz, the welding speed was 2m/s, the overlap rate was 70%, the pulse width was 8ms, and the power was 3 kW. The thickness of the selected copper foil is 430 μm, and the thickness of the selected niobium foil is 380 μm. Welding by adopting a laser welding machine in the following sequence: welding the middle position of the copper foil interlayer; and then welding the middle of the interlayer of the niobium foil.
And after welding, waiting for the sample to be cooled, opening a vacuum chamber of a welding machine to take out the sample, and finally obtaining the welding sample of the TC4 titanium alloy and the AISI 316L stainless steel.
Comparative example 1
Influence of pulse laser welding spot overlapping rate
The same material preparation method as that of example 5 was used, and the material was placed in a vacuum chamber of a laser welder and then laser-welded, except that the spot overlapping ratio was changed to 60%, wherein the welding parameters were the same as that of example 5. And after welding, waiting for the welding sample to be cooled, opening a vacuum chamber of a laser welding machine, and taking out the sample to obtain the laser welding sample of the TC4 titanium alloy and the AISI 316L stainless steel.
Comparative example 2
Influence of the welding speed of pulse laser welding
The same material preparation method as that of example 5 was used, and the material was placed in a vacuum chamber of a laser welder and then laser-welded, except that the welding speed was changed to 3mm/s, wherein the welding parameters were the same as those of example 5. And after welding, waiting for the welding sample to be cooled, opening a vacuum chamber of a laser welding machine, and taking out the sample to obtain the laser welding sample of the TC4 titanium alloy and the AISI 316L stainless steel.
Example 6
Grinding and polishing the surfaces to be welded of the TC4 titanium alloy and the AISI 316L stainless steel to ensure that the surface roughness Ra is less than or equal to 1.0 mu m; then removing an oxide film on the surface of the titanium alloy by adopting a mixed solution of hydrofluoric acid and nitric acid; and using dilute H2SO4The solution removes the oxide film on the surface of the copper foil. And then, degreasing and decontaminating the samples, putting all the samples into acetone for ultrasonic cleaning for 15min, wiping the surfaces to be welded of the samples with alcohol, and blow-drying with cold air to finally obtain clean titanium alloy, stainless steel, copper foil and niobium foil.
The processed titanium alloy, stainless steel, 430-micron copper foil and 380-micron niobium foil are sequentially placed in a butt joint mode according to the sequence of titanium alloy-niobium foil-copper foil-stainless steel, and are rigidly fixed in a clamp with a forming groove, so that the gap between the materials is ensured to be smaller than 0.1 mm.
And then, placing the assembled sample into a vacuum chamber of a laser welding machine, setting welding parameters, and welding according to a standard flow. First welding: the pulse frequency is 17Hz, the welding speed is 2m/s, the overlapping rate is 70 percent, the pulse width is 8ms, and the power is 3.5 kW; and (3) second welding: the pulse frequency was 17Hz, the welding speed was 2m/s, the overlap rate was 70%, the pulse width was 8ms, and the power was 3.5 kW. Welding by adopting a laser welding machine in the following sequence: welding the middle position of the copper foil interlayer; and then welding the middle of the interlayer of the niobium foil.
And after welding, waiting for the sample to be cooled, opening a vacuum chamber of a welding machine to take out the sample, and finally obtaining the welding sample of the TC4 titanium alloy and the AISI 316L stainless steel.
Comparative example 3
Only copper foil is used as the transition layer
Titanium alloy, stainless steel and copper foil were prepared in the same manner as in example 6. The 430 μm copper foil is placed between the titanium alloy and the stainless steel, and then assembled in the order stainless steel-copper foil-titanium alloy and placed in the vacuum chamber of a laser welder. The test specimens were rigidly fixed in a jig with a shaped groove to ensure that the gap between the materials was less than 0.1 mm.
Then setting welding process parameters, and then welding according to a standard flow. And in the welding process, the laser is aligned to the middle position of the copper foil for welding. The laser parameters were as follows: the pulse frequency was 17Hz, the welding speed was 2m/s, the overlap rate was 70%, the pulse width was 8ms, and the power was 3.5 kW. And after welding, waiting for the sample to be cooled, opening a vacuum chamber of a welding machine to take out the sample, and finally obtaining the welding sample of the TC4 titanium alloy and the AISI 316L stainless steel.
Comparative example 4
The transition layer is made of niobium foil only
Titanium alloy, stainless steel and copper foil were prepared in the same manner as in example 6. The 380 μm niobium foil is placed between the titanium alloy and the stainless steel, and then the titanium alloy is placed in the vacuum chamber of a laser welder after being assembled in the order of stainless steel-niobium foil-titanium alloy. The test specimens were rigidly fixed in a jig with a shaped groove to ensure that the gap between the materials was less than 0.1 mm.
Then setting welding process parameters, and then welding according to a standard flow. And during welding, the laser is aligned to the middle position of the niobium foil for welding. The laser parameters were as follows: the pulse frequency was 17Hz, the welding speed was 2m/s, the overlap rate was 70%, the pulse width was 8ms, and the power was 3.5 kW. And after welding, waiting for the sample to be cooled, opening a vacuum chamber of a welding machine to take out the sample, and finally obtaining the welding sample of the TC4 titanium alloy and the AISI 316L stainless steel.
Comparative example 5
In comparison with example 5, the comparative example uses a copper foil having a thickness of 390 μm and a niobium foil having a thickness of 330 μm, and the rest is the same as example 5.
Comparative example 6
In comparison with example 5, the copper foil used in this comparative example has a thickness of 450 μm and the niobium foil has a thickness of 400 μm, and the rest is the same as example 5.
The workpieces welded in the above examples 5-6 and comparative examples 1-4 were tested to compare the effects of different process, intermediate and other parameters on the pulse laser welding of titanium alloy and stainless steel.
TABLE 2 mechanical Properties of welded parts of titanium alloy/stainless Steel
| Test specimen | Tensile strength (MPa) | Fracture properties |
| Example 5 | 335.6 | Toughness of |
| Comparative example 1 | 210.8 | Toughness of |
| Comparative example 2 | 186.7 | Toughness of |
| Example 6 | 223.6 | Toughness of |
| Comparative example 3 | 198.6 | Toughness of |
| Comparative example 4 | 123.4 | Brittleness |
| Comparative example 5 | 237.6 | Brittleness |
| Comparative example 6 | 260.1 | Brittleness |
According to test results, the welding method of the stainless steel and the titanium alloy can reduce the melting amount of the titanium alloy and the stainless steel, prevent the diffusion and reaction of excessive titanium element and iron element, and is beneficial to improving the quality of a welded joint. When the adopted laser power is smaller or larger, the joint strength is not favorably increased. When only a niobium foil interlayer is used, some brittle ferrocolumbium intermetallic compounds are generated in the weld and are detrimental to the strength of the joint. When only the copper foil interlayer is adopted, copper-iron intermetallic compounds can be generated in the welding line, which is not beneficial to improving the quality of the joint. The reduction of the overlapping rate of the welding spots and the increase of the welding speed can lead to the unconcentration of energy, thereby leading to the insufficient amount of the welding seam melting. In addition, the thickness of the middle layer has great influence on the joint, and the performance of the joint is not improved easily due to the fact that the middle layer is too thin or too thick. Therefore, the method adopts copper foil and niobium foil as an intermediate layer, the thickness of the copper foil is 430 μm, the thickness of the niobium foil is 380 μm, the laser power is 3kW, the pulse width is 8ms, the welding speed is 2mm/s, and the welding spot overlapping rate is 70% as the optimal process parameters.
Claims (4)
1. A dissimilar metal pulse laser welding method for titanium alloy and stainless steel is characterized by comprising the following steps:
(1) cleaning the surface of a welding sample: cleaning surfaces to be welded of titanium alloy and stainless steel, copper foil and niobium foil to obtain a welding sample with a clean surface; the thickness of the copper foil is 400-450 mu m, and the thickness of the niobium foil is 350-400 mu m;
(2) placing a welding sample: sequentially butting and placing the titanium alloy, the stainless steel, the copper foil and the niobium foil after surface cleaning; the sequence is as follows: titanium alloy-niobium foil-copper foil-stainless steel, or stainless steel-copper foil-niobium foil-titanium alloy;
(3) welding: the welding is two welding, which respectively comprises the following steps:
first welding: aligning a laser beam to the middle position of the copper foil interlayer for welding, wherein the process parameters are as follows: the pulse frequency is 15-20Hz, the welding speed is 1-3m/s, the overlapping rate is 50-80%, the pulse width is 5-9ms, and the power is 1.5-3.5kW
And (3) second welding: and (3) aligning a laser beam to the middle position of the interlayer of the niobium foil for welding, wherein the process parameters are as follows: the pulse frequency is 15-20Hz, the welding speed is 1-3m/s, the overlapping rate is 50-80%, the pulse width is 5-9ms, and the power is 1.5-3.5 kW.
2. The dissimilar metal pulse laser welding method for a titanium alloy and a stainless steel according to claim 1, characterized in that: in the step (1), the method for cleaning the surfaces to be welded of the titanium alloy and the stainless steel comprises the following steps: sanding by using sand paper and polishing to ensure that the surface roughness Ra of the sand paper is less than or equal to 1.0 mu m; removing an oxide film on the surface of the titanium alloy by adopting a mixed solution of hydrofluoric acid and nitric acid; by dilute H2SO4Removing the oxide film on the surface of the copper foil by using the solution; and then, putting the processed welding sample, copper foil and niobium foil into an acetone solution for ultrasonic cleaning for 10-15min, wiping the surface with alcohol, drying by cold air to avoid introducing impurities, and finally obtaining clean titanium alloy, stainless steel, copper foil and niobium foil to be welded.
3. The method for pulse laser welding dissimilar metals to titanium alloy and stainless steel according to claim 1,
the first welding: the pulse frequency is 16-18Hz, the welding speed is 1.5-2.5m/s, the overlapping rate is 60-80%, the pulse width is 6-9ms, and the power is 2-3.5 kW;
and the second welding: the pulse frequency is 16-18Hz, the welding speed is 1.5-2.5m/s, the overlapping rate is 60-80%, the pulse width is 6-9ms, and the power is 2-3.5 kW.
4. The pulsed laser welding method for dissimilar metals of a titanium alloy and a stainless steel according to claim 1, wherein the titanium alloy is a TC4 titanium alloy, and the stainless steel is 316L stainless steel.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010158717.4A CN111299833A (en) | 2020-03-09 | 2020-03-09 | Dissimilar metal pulse laser welding method for titanium alloy and stainless steel |
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| CN113084345A (en) * | 2021-04-19 | 2021-07-09 | 哈尔滨工业大学（威海） | Dissimilar material scanning laser welding method based on energy regulation |
| CN114309947A (en) * | 2022-02-14 | 2022-04-12 | 东莞市逸昊金属材料科技有限公司 | Laser welding method for zirconium-based amorphous metal material and stainless steel material |
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