CN110125619B

CN110125619B - Electron beam welding repair method for large-thickness titanium alloy I-shaped welding part

Info

Publication number: CN110125619B
Application number: CN201910404228.XA
Authority: CN
Inventors: 刘艳梅; 许磊; 高峰
Original assignee: Shenyang Aircraft Industry Group Co Ltd
Current assignee: Shenyang Aircraft Industry Group Co Ltd
Priority date: 2019-05-16
Filing date: 2019-05-16
Publication date: 2020-11-13
Anticipated expiration: 2039-05-16
Also published as: CN110125619A

Abstract

The invention belongs to the technical field of machining, and relates to an electron beam welding repairing method for a large-thickness titanium alloy I-shaped welding part. Firstly, cutting out a defect part on the premise of ensuring that a part is not deformed; then, carrying out heat treatment together with the fixed connecting rod clamping device to eliminate internal stress generated by cutting off the welding seam; then, filling the solid materials which are equivalent to the two sides of the thickness of the cut part and are respectively added with 3mm of allowance; adding T-shaped process compensation blocks at two ends of the filler which is processed to be I-shaped; after adopting electron beam welding, carrying out electron beam heat treatment system for heat treatment; finally, processing in place according to the size requirement of the part to carry out relevant special inspection; the method is suitable for repairing the parts exceeding the standard defect produced in the welding process of all the titanium alloy with the large-thickness I-shaped structure, can reduce the welding defect, controls the welding deformation, achieves the effect of quickly and effectively repairing the defective parts, and has good economic benefit.

Description

Electron beam welding repair method for large-thickness titanium alloy I-shaped welding part

Technical Field

The invention belongs to the technical field of machining, and relates to an electron beam welding repairing method for a large-thickness titanium alloy I-shaped welding part.

Background

With the development of the aviation and aerospace industries, the trend of large-scale application of titanium alloy components is more and more obvious, and the use of welding parts is often the most economically feasible scheme in terms of forging capability and manufacturing cost. However, the weld may have weld defects, particularly for titanium alloys, which are refractory metals of large thickness. How to treat welding defects is one of the difficulties in the welding process. Some large-scale titanium alloy I-shaped welding parts are of large-thickness flat plate butt joint structures in a welding state, and after welding, due to overlarge size, special detection means such as X-ray cannot realize the inspection of the quality of a welding seam, and the internal quality of the welding cannot be judged. Only when the I-shaped structure is machined to the final thickness after welding, X-ray detection and the like can be accurately carried out, and whether defects exist or not and whether the sizes of the defects are within a standard allowable range or not are determined. However, once the weld quality of the final I-shaped structure exceeds the repair welding condition allowed by the standard or the repair welding is not qualified within the specified repair welding times, the whole weld cannot be used. At this time, even if the original defective welding seam is wholly removed and cut and rewelded in performance, the welding quality is difficult to ensure by re-welding due to the I-shaped structure with the final size, and further parts are scrapped, so that once the situation occurs, the economic loss is huge.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides an electron beam welding repair method for a large-thickness titanium alloy I-shaped welding part, which comprises the steps of removing a defect part, returning the I-shaped part processed to the position to an original butt joint type welding joint type by adopting a process compensation mode, and then carrying out electron beam welding repair, thereby meeting the use requirement of the part.

When the defect size of the I-shaped welded part of the large-thickness titanium alloy exceeds the normal repair welding range allowed by the standard or the defect cannot be eliminated within the specified repair welding times, the part cannot be used generally. The parts to be saved only need to cut off the welding seam at the defective position. However, when the original welding seam is removed or a part of defects are removed integrally when the final size is obtained, and then the defects are repaired by adopting a welding mode, two main problems need to be solved: firstly, how to control to finish welding repair work under the condition of small deformation; and secondly, how to design the structure of the repair weld crater of the I-shaped part which is processed to the final size. I.e. which process to repair? How is the welded structure? The traditional manual repair welding scheme cannot ensure welding deformation, has large human factors, needs grooves, has large repair welding seam area, needs gas protection in the repair welding process, and is easy to generate oxidation. The electron beam welding as an advanced welding technology has obvious advantages in large penetration or deformation control of large-thickness large titanium alloys, and can solve the first problem. The invention adopts a special electron beam welding technology to repair the parts with the problems. The general conventional electron beam repairing method can not be realized basically, the butt joint of the I-shaped structure is not a normal welding structure, and the nail tip defect of an electron beam welding seam can not be eliminated at a transverse and longitudinal junction point. The invention not only solves the problem of eliminating the nail tip defect of electron beam welding repair, but also well controls the welding deformation in the repair process.

In order to achieve the purpose, the technical scheme of the invention is as follows:

an electron beam welding repair method for a large-thickness titanium alloy I-shaped welding part comprises the following steps of firstly, cutting off a defect part of an I-shaped part with a final size on the premise of ensuring that the part is not deformed, and fixing two parts to be cut off by a fixed connecting rod clamping device in advance; then, carrying out heat treatment together with the fixed connecting rod clamping device to eliminate internal stress generated by cutting off the welding line; then, filling solid materials which are of the same mark, the same fiber direction and the same state and are equivalent to the fact that 3mm of allowance is added on two sides of the thickness of the cut-off part respectively, wherein the allowance is used for eliminating undercut generated by repairing the welding line; meanwhile, process compensation blocks are added to two ends of the filler processed to be I-shaped, the compensation blocks are T-shaped, 4 blocks are arranged on the front side and the back side, the two sides of the I-shaped part are embedded, the two sides are filled, and the filler blocks and the to-be-welded joint are used for restoring the to-be-welded joint to a conventional butt-welded joint structure; then, repairing the part by adopting electron beam welding; after adopting electron beam welding, carrying out electron beam heat treatment system for heat treatment; finally, processing in place according to the size requirement of the part to carry out relevant special inspection;

the method specifically comprises the following steps:

step one, positioning: firstly, carrying out X-ray nondestructive testing, and determining an original welding seam area by contrasting an X-ray negative film; combining the width of the heat affected zone accumulated during the exploration of the original parameters, processing the sample if the width of the heat affected zone is not recorded, performing metallographic corrosion on a section welding seam after welding to determine the width of the heat affected zone, determining the theoretical position of the original welding seam by using a sample plate, and marking the theoretical position, the original welding seam area and the edge position of the heat affected zone for machining and removing;

step two, machining and removing: according to the determined defect position and size by scribing, completely cutting off the defect by adopting numerical control equipment; in order to avoid deformation, the two ends of the I-shaped part 1 are fixed by a connecting rod or other fixing clamps in advance before cutting off, bolt holes are processed on the two sides of the connecting rod, and the positions can be connected by using bolts by utilizing holes existing in the I-shaped part 1, so that the I-shaped part 1 is ensured not to deform;

thirdly, heat treatment after cutting: carrying out vacuum heat treatment on the cut belt clamping device or the fixed rod together for releasing stress;

fourthly, assembling and grinding: after the I-shaped part is cut off, the material with the same mark as the part is adopted, the direction of the fiber of the cut part is consistent, and a section of filling block 3 is processed by a numerical control machine tool according to the size of the gap, so that the short frame and the gap can be accurately butted;

processing a T-shaped process compensation cushion block 2, filling the notch of the I-shaped part 1, ensuring the thickness of the material of the welding part, wherein the fit clearance between the T-shaped process compensation cushion block 2, the filling block 3 and the I-shaped part 1 is less than 0.1mm, and the misalignment is less than 0.1 mm; the lead-in and lead-out plate 4 is processed, and the joint clearance and dislocation meet the welding requirement; note that all profiles must be added in place by a numerical controller in order to ensure the quality of the surface cleaned before welding;

fifthly, cleaning: polishing each surface of the I-shaped part 1 by using a metal brush within a range of 20mm from the edge of the joint and butting end faces until metal luster appears; carefully wiping all surfaces of the part with white cotton cloth dipped in acetone; the parts after wiping are required to be free of oil, rust, oxides, dust, dirt, grease, or any other foreign matter;

sixthly, assembling: cleaning all surfaces of the welding tool by using acetone, and avoiding oil stains and dust; installing the I-shaped part 1 into a welding tool according to the positioning hole to be matched with the filling block 3, and pressing the I-shaped part tightly to ensure that the gap of the part to be welded is not more than 0.10mm and the misalignment is not more than 0.2 mm; fixing the lead-in lead-out plate by adopting a lead-in lead-out plate 4 clamping device, and then adding a T-shaped process compensating cushion block 2 into an I-shaped groove opening of the I-shaped part 1; the surfaces of all assembled parts to be welded and process accessories are clean, free of oil stains and dust;

seventh step, manual pre-positioning: manual positioning welding spots are positioned and added among the lead-in lead-out plate 4, the T-shaped process compensation cushion block 2 and the filling block 3 to ensure the relative positions of parts, and then a backing plate 5 is positioned;

eighth step, positioning welding: moving the positioned part into a vacuum chamber, vacuumizing, and performing electron beam positioned welding on a welding seam position, wherein the positioning depth is preferably 2-3 mm;

ninth, welding: selecting original welding parameters corresponding to the thickness of the butt joint formed after the repair welding parts are supplemented, and increasing the amplitude of electromagnetic scanning; after welding, vacuum heat preservation is carried out for more than 40 minutes, and the phenomenon that the workpiece is oxidized due to overhigh temperature of the part is prevented;

tenth, postweld heat treatment: after repairing the parts, carrying out postweld heat treatment according to an electron beam postweld heat treatment system;

step ten, subsequent machining and inspection of parts: and machining by using a numerical control machine according to the size and the requirement of the part digital model, and performing X-ray inspection and fluorescent inspection after machining.

The invention has the beneficial effects that:

1. the I-shaped part is one of the most widely applied structures in industry, and the method is suitable for repairing the parts exceeding the standard defects generated in the welding process of all the titanium alloys with the large-thickness I-shaped structures, and has wide application range.

2. The welding parameters adopting repair welding are that the thickness of the part is determined by recovering the original butt joint structure after filling, and the repair welding does not need to be searched again and is more convenient to apply

3. The method is carried out in a vacuum environment, does not oxidize and is particularly suitable for titanium alloy which is an active metal.

4. The welding defect can be reduced, the welding deformation is controlled, the effect of quickly and effectively repairing the defective part is achieved, and the economic benefit is good.

Drawings

FIG. 1 is a schematic diagram of a damascene defect compensation block and a fill block;

FIG. 2 is a schematic view of direction A;

FIG. 3 is a top view of the electron beam repair fracture repair joint positioning;

FIG. 4 is a positioning front view of an electron beam repaired fracture repair joint;

in the figure: 1 an I-shaped part; 2T type process compensation block; 3 filling blocks; 4 leading in an extraction plate; 5 backing plates.

Detailed Description

The present invention will be further described with reference to the following embodiments and the accompanying drawings, which take a large titanium alloy i-shaped circular welding frame as an example.

An electron beam welding repair method for a large-thickness titanium alloy I-shaped welding part comprises the following steps of firstly, cutting off a defect part of an I-shaped part with a final size on the premise of ensuring that the part is not deformed, and fixing two parts to be cut off by a fixed connecting rod clamping device in advance; then, carrying out heat treatment together with the fixed connecting rod clamping device to eliminate internal stress generated by cutting off the welding line; then, filling solid materials which are of the same mark, the same fiber direction and the same state and are equivalent to the fact that 3mm of allowance is added on two sides of the thickness of the cut-off part respectively, wherein the allowance is used for eliminating undercut generated by repairing the welding line; meanwhile, process compensation blocks are added at two ends of the filler processed to be I-shaped, the compensation blocks are T-shaped, 4 blocks are arranged on the front side and the back side, the two sides of the I-shaped part are embedded, the two sides are filled, and the filler blocks and the to-be-welded joint are used for restoring the to-be-welded joint to a conventional butt-welded joint structure. Then, repairing the part by adopting electron beam welding; after adopting electron beam welding, carrying out electron beam heat treatment system for heat treatment; finally, processing in place according to the size requirement of the part to carry out relevant special inspection;

the method specifically comprises the following steps:

thirdly, heat treatment after cutting: carrying out vacuum heat treatment on the cut belt clamping device or the fixed rod together for releasing stress; because the internal stress can be released when the I-shaped part 1 is cut off, although the clamping and fixing device is adopted for carrying out original fixing, if further stress release and redistribution are not carried out, the deformation control during repair welding of the part is not facilitated, and on the other hand, the stress concentration of a welding seam part can be caused;

processing a T-shaped process compensation block 2, filling the notch of the I-shaped part 1 to ensure that the thickness of the material of the welding part is ensured, wherein the fit clearance among the T-shaped process compensation block 2, the filling block 3 and the I-shaped part 1 is less than 0.1mm, and the misalignment is less than 0.1 mm; the lead-in and lead-out plate 4 is processed, and the joint clearance and dislocation meet the welding requirement; note that all profiles must be added in place by a numerical controller in order to ensure the quality of the surface cleaned before welding;

fifthly, cleaning: polishing each surface of the I-shaped part 1 by using a metal brush within a range of 20mm from the edge of the joint and butting end faces until metal luster appears; carefully wiping all surfaces of the part with white cotton cloth dipped in acetone; the parts after wiping are required to be free of oil, rust, oxides, dust, dirt, grease, or any other foreign matter; the welding seam surface is matched with a plurality of curved surfaces, so that the welding seam is difficult to clean; during cleaning, all surfaces of the I-shaped part 1, particularly the surfaces which are in direct contact with the T-shaped process compensation block 2, must be cleaned, so that air holes caused by incomplete cleaning are avoided;

sixthly, assembling: cleaning all surfaces of the welding tool by using acetone, and avoiding oil stains and dust; installing the I-shaped part 1 into a welding tool according to the positioning hole to be matched with the filling block 3, and pressing the I-shaped part tightly to ensure that the gap of the part to be welded is not more than 0.10mm and the misalignment is not more than 0.2 mm; fixing the lead-in and lead-out plate by adopting a lead-in and lead-out plate 4 clamping device, and then adding a T-shaped process compensation block 2 into an I-shaped groove opening of the I-shaped part 1; the surfaces of all assembled parts to be welded and process accessories are clean, free of oil stains and dust; note that: the whole operation needs to be provided with clean fluffless white gloves, so that the inner surfaces of the welding seams cannot be touched;

seventh step, manual pre-positioning: manual positioning welding spots are positioned and added among the lead-in lead-out plate 4, the T-shaped process compensation block 2 and the filling block 3 to ensure the relative positions of parts, and then a backing plate 5 is positioned; note that: the manual and positioning are not suitable for overlarge current;

eighth step, positioning welding: moving the positioned part into a vacuum chamber, vacuumizing, and performing electron beam positioned welding on a welding seam position, wherein the positioning depth is preferably 2-3 mm; sectional positioning can be considered if the welding seam is long;

ninth, welding: selecting original welding parameters corresponding to the thickness of a butt joint formed after the repair welding part is supplemented, and increasing the amplitude of electromagnetic scanning so as to reduce the influence of the T-shaped process compensation block 2 and the I-shaped part 1 on the adverse air hole overflow caused by excessive contact surfaces; after welding, vacuum heat preservation is carried out for more than 40 minutes, and the phenomenon that the workpiece is oxidized due to overhigh temperature of the part is prevented;

Claims

1. An electron beam welding repair method for a large-thickness titanium alloy I-shaped welding part is characterized by comprising the following steps:

step two, machining and removing: according to the determined defect position and size by scribing, completely cutting off the defect by adopting numerical control equipment; in order to avoid deformation, the two ends of the connecting rod or other fixing clamps are fixed in advance before cutting off, bolt holes are machined in the two sides of the connecting rod, holes existing in the I-shaped part (1) can be used in the positions, and the I-shaped part (1) is connected through bolts, so that the I-shaped part (1) is guaranteed not to deform;

fourthly, assembling and grinding: after the I-shaped part is cut off, the material with the same mark as the part is adopted, the direction of the fiber of the cut part is consistent, and a section of filling block (3) is processed by a numerical control machine according to the size of the gap, so that the short frame and the gap can be accurately butted;

processing a T-shaped process compensation cushion block (2), filling the notch of the I-shaped part (1) to ensure the thickness of the material of the welding part, wherein the fit clearance between the T-shaped process compensation cushion block (2), the filling block (3) and the I-shaped part (1) is less than 0.1mm, and the misalignment is less than 0.1 mm; processing an introduced lead-out plate (4), wherein the joint clearance and dislocation meet the welding requirement; note that all profiles must be added in place by a numerical controller in order to ensure the quality of the surface cleaned before welding;

fifthly, cleaning: polishing each surface of the I-shaped part (1) by using a metal brush within 20mm from the edge of the joint and butting end faces until metal luster appears; carefully wiping all surfaces of the part with white cotton cloth dipped in acetone; the parts after wiping are required to be free of oil, rust, oxides, dust, dirt, grease, or any other foreign matter;

sixthly, assembling: cleaning all surfaces of the welding tool by using acetone, and avoiding oil stains and dust; installing the I-shaped part (1) into a welding tool according to the positioning hole to be matched with the filling block (3), and pressing the I-shaped part tightly to ensure that the gap of the part to be welded is not more than 0.10mm and the misalignment is not more than 0.2 mm; fixing the lead-in lead-out plate by adopting a lead-in lead-out plate (4) clamping device, and then adding a T-shaped process compensation cushion block (2) into an I-shaped groove opening of the I-shaped part (1); the surfaces of all assembled parts to be welded and process accessories are clean, free of oil stains and dust;

seventh step, manual pre-positioning: manual positioning welding points are positioned and added among the lead-in lead-out plate (4), the T-shaped process compensation cushion block (2) and the filling block (3) to ensure the relative positions of parts of each part, and then a backing plate (5) is positioned;

eighth step, positioning welding: moving the positioned part into a vacuum chamber, vacuumizing, and performing electron beam positioned welding on a welding seam position, wherein the positioning depth is 2-3 mm;