CN114434086B - Surface crack repairing method for titanium alloy thin-wall part - Google Patents
Surface crack repairing method for titanium alloy thin-wall part Download PDFInfo
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- CN114434086B CN114434086B CN202111606339.2A CN202111606339A CN114434086B CN 114434086 B CN114434086 B CN 114434086B CN 202111606339 A CN202111606339 A CN 202111606339A CN 114434086 B CN114434086 B CN 114434086B
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Abstract
Aiming at the repair requirement of the titanium alloy thin-wall part with the thickness of 0.5-0.7 mm, the method aims at overcoming the defects of poor feasibility, hemming burning-through during arcing, large thermal stress after fusion welding and complex post-welding heat treatment process in the prior repair technology. The invention provides a method for repairing cracks on the surface of a titanium alloy thin-wall part, which considers that laser cladding laser heat is concentrated, and a titanium alloy skin cannot be curled and burnt through when laser cladding is carried out with low power. But the low power can not fully melt the titanium alloy powder, the laser cladding technology and the direct current argon arc welding technology are combined, and the argon arc welding is used for further melting and filling the titanium alloy powder on the basis of cladding the titanium alloy powder, so that the repairing of the surface cracks of the ventral fin titanium alloy skin is realized, the repairing efficiency is improved, the quality of a cladding layer is ensured, the repairing cost is reduced, the pneumatic appearance of the ventral fin structure is restored, the surrounding area is not damaged, the structural bearing capacity is ensured, and the problem of repairing the bottleneck of the surface cracks of the ventral fin titanium alloy skin is solved.
Description
Technical Field
The invention relates to a method for repairing surface cracks of a titanium alloy thin-wall part, which combines a laser cladding technology and an argon arc welding technology to realize the repair of surface crack faults of a titanium alloy skin of an aircraft ventral fin of a titanium alloy thin-wall part with the thickness of 0.5 mm-0.7 mm.
Background
In the overhauling process of a certain aircraft, the joint of the surface of the ventral fin titanium alloy skin and the internal reinforcing rib is found to have a plurality of cracks, the lengths of the cracks are 17 cm-25 cm, the cracks extend along the joint of the surface titanium alloy skin and the reinforcing rib, and the crack fault damage is deeper and penetrates through the second layer, so that the use safety of the aircraft is seriously endangered. If the belly fin is directly repaired by adopting a new product replacement mode, the maintenance cost is too high, and the belly fin is scrapped and disposed of seriously due to crack failure. Secondly, the repair manufacturer does not have a production and manufacturing means, has long period of purchasing new products externally, is limited by people, and is difficult to ensure the normal delivery period of the aircraft. Therefore, the development of the ventral fin surface crack repair technology can effectively avoid resource waste, shorten the repair period and have great economic benefit.
The ventral fin is of a titanium alloy double-layer thin-wall structure, the materials are TC4 titanium alloy, the ventral fin is manufactured by superplastic forming and diffusion connection, the thickness of the outermost titanium alloy skin is about 0.5 mm-0.7 mm, the thickness of the second titanium alloy skin is not more than 1mm, and the interlayer is provided with glue solution. The titanium alloy has the characteristics of high melting point, active chemical property, poor thermal conductivity, large thermal capacity and the like, is extremely easy to oxidize at high temperature to influence welding quality, and has high repair difficulty. The traditional argon arc welding repair technology has the defects that the heat input amount is large, the thickness of the surface layer of the titanium alloy skin is 0.5 mm-0.7 mm, the titanium alloy skin is easy to turn up, even the titanium alloy skin is directly burnt through, and the fault range is enlarged; the titanium alloy interlayer is filled with glue solution, the melting point of the glue solution is much lower than that of the titanium alloy, and the glue solution is easy to enter a molten pool after being melted, so that dense air holes are generated in the titanium alloy welding seam; and the gas generated after the glue solution is burnt can not directly act on the upper part of the molten pool by argon arc welding protective gas argon, so that titanium alloy is oxidized. The laser cladding technology belongs to precision machining, not only can control the repairing track, but also can strictly control the thickness of the cladding layer by adjusting the laser power and the powder feeding amount, has the remarkable advantages of small heat input amount, small influence on the structure and performance of a matrix material and the like, and can be applied to repairing the titanium alloy thin-wall part.
The invention creation of the publication No. CN1966201 discloses a laser deposition repair method of a titanium alloy thin-wall shell, which can realize metallurgical bonding of a cladding layer and a matrix by cleaning a solder electrolytic etching layer and vacuum annealing and dehydrogenation of the solder and then laser deposition under the protection of argon, has small heat affected zone and small deformation of the matrix, has a repair material of BT20 and a wall thickness of 2mm, and has the risk of burning through of the thin-wall part for the ventral fin thin-wall part with the thickness of 0.5 mm-0.7 mm.
In the invention with publication number CN109207988AThe cold spraying powder for repairing the surface damage of the titanium alloy thin-wall part and the repairing method are provided, and TC4, ti and Al are mixed by using He as carrier gas 2 O 3 The mixed powder is sprayed on the damaged surface of the titanium alloy thin-wall plate in a cold mode, heat input of powder spraying deposition is reduced, and heat treatment is conducted on the titanium alloy thin-wall plate after deposition. The method is used for repairing crack faults, and has the advantages of low cold spraying bonding strength, large powder porosity, non-compact structure and falling risk in the use process of the aircraft.
The invention of the publication No. CN110983103A discloses a 3D printing laser repairing method of TB6 titanium alloy, and laser strengthening processing is carried out on the surface of the titanium alloy by adjusting laser process parameters, so that a laser remanufacturing repairing layer with no air hole defect and good performance is obtained. TB6 is beta-type titanium alloy, TC4 is alpha+beta-type titanium alloy, the two alloys are different in type and large in performance difference, and the laser has large power (900W-2000W) and is not suitable for repairing thin-wall parts.
The invention creation of the publication No. CN113088962A discloses a laser cladding multidirectional repair method for a damaged piece of a titanium alloy thin-wall blade, wherein the laser power is 700W-1000W, a plurality of columns are clad on a groove by using coaxial powder feeding laser cladding in a direction from left to right of the groove opening, and the columns are clad in a spiral ascending mode from the groove bottom to the groove opening. The laser power in the invention is up to 1000W, the heat input is too large, the deformation of the thin-wall part is easy to be caused, and the method is not suitable for repairing the ventral fin thin-wall part.
The invention with the publication number of CN1224494C discloses a local efficient cooling method for thin-wall parts in laser cladding, thermal spraying and welding processing, and the problems of excessive heating, deformation, overburning, burning-through and the like of the parts in the unstable state severe heating process can be effectively prevented by arranging lead sheets and tin sheets below welding seams. Unfortunately, this method still does not address the issues of hemming and ablation of the arching titanium alloy skin during repair.
The technical research of the Shenyang aircraft technology (group) of the middle aviation industry is published in the journal of test and mechanism analysis in 2012 by the technical research institute of Shenyang aircraft technology (group), and the comparative test is carried out on the results of TA15 titanium alloy samples for repairing the titanium alloy surface by laser cladding and argon arc welding, so that the laser cladding can realize the effective repair of the titanium alloy surface defect, and the performances of the method are far higher than those of the argon arc welding repair. The test is not comprehensive enough, and aiming at irregular complex defects, the accessibility of a laser area is poor, the operability is poor, and the bonding strength of cladding powder and a matrix needs to be improved.
Disclosure of Invention
Based on the background technology, aiming at the repair requirement of the titanium alloy thin-wall part with the thickness of 0.5 mm-0.7 mm, the defects of poor feasibility, hemming burning-through during arcing, large thermal stress after fusion welding and complex post-welding heat treatment process in the prior repair technology are overcome. The invention provides a method for repairing cracks on the surface of a titanium alloy thin-wall part, which considers that laser cladding laser heat is concentrated, and a titanium alloy skin cannot be curled and burnt through when laser cladding is carried out with low power. But the low power can not fully melt the titanium alloy powder, the laser cladding technology and the direct current argon arc welding technology are combined, the argon arc welding is used for further melting and filling the titanium alloy powder on the basis of cladding the titanium alloy powder, and repairing of the surface cracks of the ventral fin titanium alloy skin is realized.
The invention is characterized in that: firstly, in order to prevent the glue solution of the interlayer of the titanium alloy sheet from being heated, melted and gushed out to pollute the surface to be repaired and ensure the bonding strength of a matrix and a cladding layer, the invention is based on laser cladding equipment, TC4 alloy powder (the powder is too thin, solid and has poor flowability, which leads to uneven powder feeding, insufficient thick melting and easy defect formation) which is made of the same material as the ventral fin matrix and has the particle size of 75-125 mu m is adopted, argon is used as a protective gas, the problems of titanium alloy oxidation and molding in the laser cladding process are mainly solved, proper laser cladding process parameters are selected, energy input is precisely controlled (low-power laser is adopted), and secondary damage is prevented. And then, using argon arc welding equipment, and adopting a low-current process to carry out direct-current argon arc welding fusion on the uneven and unfused areas of the cladding layer, so that the surface is smoothly transited, and the bonding quality of the cladding layer is improved.
The technical scheme of the invention is as follows:
a method for repairing cracks on the surface of a titanium alloy thin-wall part is characterized by comprising the following steps:
step 1: pre-weld treatment
1.1, polishing the surface of a titanium alloy thin-wall part cleanly until the metallic luster is exposed, finding out all cracks on the titanium alloy thin-wall part, polishing the back of the area where the cracks penetrate through the wall thickness of the titanium alloy to the metallic luster, chamfering the positions of the found cracks to facilitate the adhesion and cladding of the titanium alloy powder, and punching crack-stopping holes at two ends of the cracks penetrating through the wall thickness of the titanium alloy after chamfering the cracks;
1.2, polishing the surface to be repaired to be smooth, and removing stains on the surface of the thin-wall part;
1.3, protecting the areas needing no repair near the cracks, and preventing laser sputtering damage;
1.4, introducing inert protective gas into a cavity formed by the titanium alloy thin-wall parts;
step 2: laser cladding repair
2.1, selecting TC4 titanium alloy powder with the powder particle diameter of 75-125 mu m for drying, wherein the drying temperature is 130+/-5 ℃, the drying time is not less than 4 hours, and the vacuum degree is-0.8-1 bar;
2.2 determination of repair Path
Determining the number of laser cladding channels and the number of layers according to the width and the depth of the groove formed by the crack on the surface of the titanium alloy skin, wherein the surface of the cladding layer is higher than the surface of the titanium alloy thin-wall part;
2.3 laser cladding
2.3.1 preheating before repair:
firstly, preheating a surface to be repaired by adopting low-power laser with the power of 200-300W, wherein the number of preheating layers is 1, the lens protection air flow is 8-12L/min before preheating, the powder feeding air flow is 6-10L/min, the powder feeding speed is 1-1.2r/min, and the scanning speed of a laser cladding head is 400mm/min;
2.3.2 surface repair welding:
carrying out surface repair by adopting 400-500W laser power, wherein during the surface repair, the lens protection air flow, the powder feeding speed and the scanning speed of the laser cladding head are consistent with the preheating parameters before 2.3.1 medium repair;
step 3: DC argon arc welding
Selecting a TC4 welding wire, and welding the welding current of 20-30A to fuse the uneven and unfused areas of the cladding layer so as to smoothly transition the welding surface;
step 4: grinding allowance
Polishing the allowance to make the repair surface smooth and consistent with the surface roughness of the titanium alloy thin-wall part;
step 5: nondestructive flaw detection;
step 6: and (5) metallographic test.
Further, the groove formed in the step 1.1 is a V-groove.
Further, the step 4 specifically includes:
and 4.1, grinding the cladding layer higher than the surface of the titanium alloy skin by adopting a grinding wheel, and reducing the processing stress a small number of times, thereby ensuring the flatness of the repair surface.
And 4.2, polishing and deburring by using fine sand paper to ensure that the surface roughness of the repairing surface is consistent with that of the titanium alloy skin.
Further, the step 5 specifically includes:
and (3) performing fluorescent inspection on the laser cladding repair area on the surface of the polished titanium alloy thin-wall part, and ensuring that the welding line and the nearby area are free from cracks and welding imperviousness defects.
Compared with the prior art, the invention has the following advantages:
1. aiming at repairing cracks on a titanium alloy thin-wall part with the thickness of 0.5 mm-0.7 mm, the laser cladding technology is adopted, inert shielding gas is used as shielding gas before and during welding, the oxidation of the surface and the back of a welding line can be effectively prevented, argon is introduced into the back of the welding line for protection and reduction of oxidation, and the heat is taken away, so that cooling is accelerated, and warping and ablation are prevented in the repairing process; through a large number of process tests and parameter debugging, preheating is adopted before laser cladding welding, the preheating power is 200W-300W, the matrix is preheated by low-power laser, the temperature difference is reduced, the stress is reduced, and overheating and burning through caused by overlarge local heating of the substrate can be effectively avoided; under the condition of ensuring the fusion quality, the laser power is strictly controlled, the fusion power is 400-500W, the heat input quantity is reduced, the deformation quantity is small, and the influence of the heating, melting and gushing of the interlayer glue solution of the titanium alloy sheet on the welding quality is effectively avoided; the laser cladding heat affected zone is small, and the influence on the matrix structure and strength is small; because the low power is adopted during cladding, the heat input is small, and under the condition of deeper cracks, partial powder is insufficiently melted, so that an argon arc welding process is required to be added on the basis of a laser cladding layer in the later stage, the powder can be ensured to be sufficiently melted, the smooth transition of a local uneven place is ensured, and the stress concentration is reduced.
2. According to the invention, on the basis of the laser cladding layer, a low-current direct-current argon arc welding process is adopted, and the welding current is controlled within a range of 20A-30A, so that the welding surface is smoothly transited, and the welding quality is further ensured.
3. The invention fully exerts the advantages of the laser cladding technology and the argon arc welding technology and can be popularized and applied to repair of titanium alloy thin-wall damaged parts in the fields of aviation, ships and automobiles.
Drawings
Fig. 1 is a diagram of a ventral fin skin failure of a titanium alloy thin-walled member of example 1.
Fig. 2 is a morphology of the ventral fin skin of the titanium alloy thin-walled member of example 1 after laser cladding repair.
Fig. 3 is a profile of the titanium alloy thin-walled workpiece ventral fin skin of example 1 after argon arc welding repair.
Fig. 4 is a profile of the titanium alloy thin-walled workpiece ventral fin skin of example 1 after polishing.
Fig. 5 is a fluorescent coloring display diagram of the ventral fin skin repair area of the titanium alloy thin-walled member of example 1.
FIG. 6 is a microstructure view of the bonding surface of the cladding layer and the substrate of the titanium alloy sample of example 1.
Fig. 7 is a morphology of the ventral fin skin of the titanium alloy thin-walled member of example 2 after laser cladding repair.
Fig. 8 is a profile of the titanium alloy thin-walled workpiece of example 2 after the ventral fin skin is repaired by argon arc welding.
Fig. 9 is a profile of example 2 titanium alloy thin-walled workpiece ventral fin skin after polishing.
Fig. 10 is a fluorescent coloring display diagram of the ventral fin skin repair area of the titanium alloy thin-walled member of example 2.
FIG. 11 is a microstructure view of the bonding surface of the cladding layer and the substrate of the titanium alloy sample of example 2.
Detailed Description
The invention is further described below with reference to the drawings and examples.
Example 1:
the embodiment is a method for repairing surface cracks of a titanium alloy thin-wall part, wherein the fault form is shown in fig. 1, a mode of combining laser cladding and direct current argon arc welding technology is adopted, technological parameters are strictly controlled to ensure structural integrity and repair quality stability of a substrate, flatness and smoothness of a repair surface are restored through grinding of a grinding wheel, defects such as cracks, unfused and the like are detected by combining a nondestructive inspection method, and the method comprises the following specific steps:
step 1: pre-weld treatment
1.1, the coating and the oxide layer on the surface of the titanium alloy skin are polished by a grinding wheel until the metallic luster is exposed, all cracks on the surface of the titanium alloy skin are found, and for the cracks penetrating the wall thickness of the titanium alloy, the coating and the oxide layer on the back surface of the titanium alloy thin-wall part where the cracks are positioned and nearby are polished until the metallic luster is exposed so as to prevent weld joint pollution. Forming V-shaped groove grooves at the positions of the found cracks to be repaired so as to facilitate the adhesion and cladding of titanium alloy powder, and for the cracks penetrating the wall thickness of the titanium alloy, forming crack stop holes at two ends of the cracks after forming the V-shaped groove grooves; in the step, when the crack is found, all the places where the crack is likely to be expanded are eliminated, one crack is expanded along the crack source, or the expanded crack is eliminated along a plurality of directions, and if the crack source is not eliminated cleanly and remains, the crack is expanded in use; whether the crack is removed cleanly or not can be judged by fluorescent examination;
1.2, polishing the surface to be repaired by 240-mesh sand paper to make the surface smooth, so that the surface of the surface is free of defects such as pits, sharp corners, burrs and the like, and cleaning greasy dirt and sweat stains on the surface of the titanium alloy skin by using alcohol;
1.3, protecting the areas which are not required to be repaired near the cracks by using a high-temperature adhesive tape, and preventing laser sputtering damage;
1.4 argon (or other inert protective gas) is introduced to protect the whole ventral fin from oxidation on the surface and back of the welding line and accelerate cooling.
Step 2: laser cladding repair
2.1 selecting TC4 titanium alloy powder with the powder particle diameter of 75-125 mu m for drying treatment, wherein the drying temperature is 135 ℃, the drying time is 4 hours, and the vacuum degree is-1 bar.
2.2 determination of repair Path
According to the width and depth of the groove formed by the crack on the surface of the titanium alloy skin, the number of laser cladding channels and the number of layers are respectively set to 6 channels and 6 layers until the cladding layer completely covers the groove, the surface of the cladding layer is higher than the surface of the titanium alloy skin, and enough machining allowance is ensured while the heat input is reduced.
2.3 laser cladding
2.3.1 preheating before repair:
in order to reduce crack initiation and ensure good fusion of a cladding layer and a matrix and strength of a bonding surface, a surface to be repaired is preheated by adopting low-power laser, the preheating laser power is 200W, and the number of preheating layers is 1 (not counted in the number of coating layers); considering the problem of molding after the titanium alloy is melted, setting the air flow of the lens protection as 8L/min and the air flow of the powder feeding as 6L/min; in order to ensure that the titanium alloy powder is well combined with the surface to be repaired, the powder feeding speed is set to be 1r/min, and the scanning speed of the laser cladding head is set to be 400mm/min.
2.3.2 surface repair welding:
in order to ensure that TC4 titanium alloy powder is fully melted and the fusion quality is improved, the heat input quantity needs to be controlled, so that the laser power is 400W during surface repair welding, and the rest parameters are consistent with the preheating parameters before laser cladding repair in 2.3.1.
The surface morphology of the repaired titanium alloy skin through laser cladding is shown in fig. 2, and the surface of the repaired cladding layer is smooth, basically free of oxidation, good in fusion condition and free of damage near the repaired area.
Step 3: DC argon arc welding
The TC4 welding wire and the welding current 20A are selected, the welding current and time of arc starting, welding and arc receiving are precisely controlled, and the uneven and unfused areas of the cladding layer are fused, so that the welding surface is smoothly transited, and the internal quality of the welding seam is ensured.
The surface appearance of the titanium alloy skin after the argon arc welding repair is shown in figure 3, the powder adhered on the surface of the cladding layer is fully melted, and the fusion quality is improved.
Step 4: grinding allowance
And 4.1, grinding the cladding layer higher than the surface of the titanium alloy skin by adopting a grinding wheel, and reducing the processing stress a small number of times, thereby ensuring the flatness of the repair surface.
And 4.2, polishing and deburring by using fine sand paper to ensure that the surface roughness of the repairing surface is consistent with that of the titanium alloy skin.
The surface morphology after polishing is shown in figure 4, the repairing surface is smooth and flat, and the technical requirements are met.
Step 5: nondestructive flaw detection
And (3) performing fluorescent inspection on the polished surface laser cladding repair area of the ventral fin, so as to ensure that the weld joint and the nearby area and the defects such as crack and welding imperviousness are avoided. The polished surface fluorescent coloring is shown in fig. 5, and it can be seen that the polished surface laser cladding repair area of the ventral fin has no crack defect and no unfused holes.
Step 6: metallographic test
In order to further verify the internal quality of the cladding layer under the condition of the technological parameters so as to combine with the thin-walled substrate member, a sample member with the same technological parameters as those of the thin-walled titanium alloy member repaired in the embodiment is selected for metallographic analysis, and a microstructure photo is shown in fig. 6. The left side of the picture is a cladding layer structure, the right side is a heat affected zone structure, and a typical lath-like as-cast structure is presented. The joint surface of the cladding layer and the matrix has no defects of microcrack, unfused, air holes, inclusions and the like, and the heat affected zone of the cladding layer is small.
Example 2:
the embodiment is a method for repairing cracks on the surface of a titanium alloy thin-wall part, which comprises the following specific steps:
step 1: pre-weld treatment
This step is the same as step 1 in example 1.
Step 2: laser cladding repair
2.1 selecting TC4 titanium alloy powder with the powder particle diameter of 75-125 mu m for drying treatment, wherein the drying temperature is 135 ℃, the time is 4 hours, and the vacuum degree is-1 bar.
2.2 determination of repair Path
And setting the number of laser cladding channels and the number of layers to 7 channels and 8 layers respectively according to the width and the depth of the groove formed by the crack until the surface of the cladding layer is higher than the surface of the titanium alloy skin, and ensuring enough machining allowance while reducing the heat input.
2.3 laser cladding
2.3.1 preheating before repair:
in order to reduce crack initiation and ensure good fusion of a cladding layer and a matrix and strength of a bonding surface, a small-power laser is adopted to preheat the surface to be repaired, the preheating laser power is 300W, the number of preheating layers is 1, the lens protection air flow is 12L/min, the powder feeding air flow is 10L/min, the powder feeding speed is 1.2r/min, and the scanning speed of a laser cladding head is 400mm/min.
2.3.2 surface repair welding:
in order to ensure that TC4 titanium alloy powder is fully melted and the fusion quality is improved, the heat input quantity is controlled, the laser power is 500W, and the rest parameters are consistent with the laser cladding preheating parameters. The surface morphology of the repaired titanium alloy skin through laser cladding is shown in fig. 7, and the surface of the repaired cladding layer is smooth, basically free of oxidation, good in fusion condition and free of damage near the repaired area.
Step 3: direct current argon arc welding:
the TC4 welding wire is selected, the welding current is 30A, the welding current and time of arc starting, welding and arc receiving are precisely controlled, the uneven and unfused areas of the cladding layer are fused, the surface is smooth, the internal quality of the welding seam is ensured, the surface appearance of the titanium alloy skin after argon arc welding is shown as figure 8, the surface coating powder of the cladding layer is fully melted, and the fusion quality is improved.
Step 4: the polishing allowance and the surface morphology after polishing are shown in figure 9, so that the repairing surface is smooth and flat, and the technical requirements are met.
Step 5: the nondestructive inspection and the fluorescent coloring are shown in fig. 10, and the polished laser cladding repair area has no crack defect and no unfused holes.
Step 6: metallographic experiments show that microstructure photographs are shown in FIG. 11, the left side of the photograph is a cladding layer structure, the right side of the photograph is a heat affected zone structure, and typical lath-like as-cast structures are shown. The joint surface of the cladding layer and the matrix has no defects of microcrack, unfused, air holes, inclusions and the like, and the heat affected zone of the cladding layer is small.
Steps 4 to 6 are the same as the method of example 1.
Claims (4)
1. A method for repairing surface cracks of a titanium alloy thin-wall part is characterized by comprising the following steps of:
step 1: pre-weld treatment
1.1, polishing the surface of a titanium alloy thin-wall part cleanly until the metallic luster is exposed, finding out all cracks on the titanium alloy thin-wall part, polishing the back of the area where the cracks penetrate through the wall thickness of the titanium alloy to the metallic luster, chamfering the positions of the found cracks to facilitate the adhesion and cladding of the titanium alloy powder, and punching crack-stopping holes at two ends of the cracks penetrating through the wall thickness of the titanium alloy after chamfering the cracks;
1.2, polishing the surface to be repaired to be smooth, and removing stains on the surface of the thin-wall part;
1.3, protecting the areas needing no repair near the cracks, and preventing laser sputtering damage;
1.4, introducing inert protective gas into a cavity formed by the titanium alloy thin-wall parts;
step 2: laser cladding repair
2.1, selecting TC4 titanium alloy powder with the powder particle diameter of 75-125 mu m for drying, wherein the drying temperature is 130+/-5 ℃, the drying time is not less than 4 hours, and the vacuum degree is-0.8-1 bar;
2.2 determination of repair Path
Determining the number of laser cladding channels and the number of layers according to the width and the depth of the groove formed by the crack on the surface of the titanium alloy skin, wherein the surface of the cladding layer is higher than the surface of the titanium alloy thin-wall part;
2.3 laser cladding
2.3.1 preheating before repair:
firstly, preheating a surface to be repaired by adopting low-power laser with the power of 200-300W, wherein the number of preheating layers is 1, the lens protection air flow is 8-12L/min before preheating, the powder feeding air flow is 6-10L/min, the powder feeding speed is 1-1.2r/min, and the scanning speed of a laser cladding head is 400mm/min;
2.3.2 surface repair welding:
carrying out surface repair by adopting 400-500W laser power, wherein during the surface repair, the lens protection air flow, the powder feeding speed and the scanning speed of the laser cladding head are consistent with the preheating parameters before 2.3.1 medium repair;
step 3: DC argon arc welding
Selecting a TC4 welding wire, and welding the welding current of 20-30A to fuse the uneven and unfused areas of the cladding layer so as to smoothly transition the welding surface;
step 4: grinding allowance
Polishing the allowance to make the repair surface smooth and consistent with the surface roughness of the titanium alloy thin-wall part;
step 5: nondestructive flaw detection;
step 6: and (5) metallographic test.
2. The method for repairing surface cracks of a titanium alloy thin-walled part according to claim 1, wherein the method comprises the following steps:
the groove formed in the step 1.1 is a V-shaped groove.
3. The method for repairing surface cracks of a titanium alloy thin-walled part according to claim 1, wherein the method comprises the following steps:
the step 4 specifically comprises the following steps:
4.1, grinding the cladding layer higher than the surface of the titanium alloy skin by adopting a grinding wheel, and reducing the processing stress a small number of times, thereby ensuring the flatness of the repair surface;
and 4.2, polishing and deburring by using fine sand paper to ensure that the surface roughness of the repairing surface is consistent with that of the titanium alloy skin.
4. The method for repairing surface cracks of a titanium alloy thin-walled part according to claim 1, wherein the method comprises the following steps:
the step 5 specifically comprises the following steps:
and (3) performing fluorescent inspection on the laser cladding repair area on the surface of the polished titanium alloy thin-wall part, and ensuring that the welding line and the nearby area are free from cracks and welding imperviousness defects.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202111606339.2A CN114434086B (en) | 2021-12-26 | 2021-12-26 | Surface crack repairing method for titanium alloy thin-wall part |
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| CN114959682A (en) * | 2022-05-13 | 2022-08-30 | 东华大学 | Preparation of Al on surface of aluminum alloy 3 Laser cladding method of Ti coating |
| CN115074725B (en) * | 2022-06-29 | 2024-01-30 | 中国航发动力股份有限公司 | Repairing method for defects of titanium alloy thin blade She Biankuai |
| CN115142702B (en) * | 2022-07-18 | 2023-07-18 | 华南理工大学 | Method for repairing shock damage Liang Zhushuan welded node based on laser material-increasing technology |
| CN115255805A (en) * | 2022-08-04 | 2022-11-01 | 湖北超卓航空科技股份有限公司 | Method for quickly repairing notch fault of aircraft wing fuel tank skin |
| CN115386873A (en) * | 2022-09-06 | 2022-11-25 | 北京航星机器制造有限公司 | Defect repairing method for TA15 titanium alloy part formed by selective laser melting |
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