External field in-situ laser additive repairing method for steel structural plate

Abstract

A steel structural plate external field in-situ laser additive repairing method comprises the steps that firstly, the range of a to-be-repaired damaged area of a steel structural plate component is determined, a laser additive repairing mode and repairing path planning are determined according to the damage type and degree, and laser cutting or laser removing is conducted on the to-be-repaired damaged area; then, the surface of the damaged area to be repaired is subjected to laser polishing treatment, and a layer of laser additive deposition is conducted; then laser remelting is conducted on the current additive repairing layer, it is ensured that the laser remelting area completely covers the laser additive area, and heat treatment is conducted on the additive area; next layer of laser additive filling repair is carried out, and the upper layer of laser additive part is covered; the steps are repeated until the laser additive completely covers the cutting area, and filling of the additive repairing area is completed; and finally, laser remelting treatment is conducted on the surface of the additive repairing area and the combined part of the additive repairing area and the base metal. According to the method, various damage types of the steel bridge after long-term service are repaired.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing, and in particular to an off-site in-situ laser additive repair method for a steel structure plate. Background Art

[0002] Corrosion damage and fatigue damage are two important failure factors that affect the performance and service quality of bridges. At present, traditional repair methods mostly use replacement of steel bridge decks or installation of reinforced steel plates, crack arrest holes and other operations to delay fatigue failure. The former consumes a lot of costs and affects daily transportation; the latter only slows down the speed of damage failure and cannot truly achieve the repair effect. Seeking new methods and using new technologies for repair is an inevitable trend.

[0003] The patent application "A laser cladding online additive repair device and repair method" (publication number CN116352115A) uses the powder feeding speed to control the composition content of the cladding powder, realizes the online adjustment of the material composition during the laser cladding process, and makes the content of the main elements of the cladding powder close to the parts to be repaired, but it cannot realize the in-situ repair of large-scale bridge damage in the field; the patent application "A laser additive repair method for rail bolt holes" (publication number CN115847002A) uses the method of additive repair after cutting processing to realize the repair of rail bolt holes, but it cannot realize the in-situ repair of large-scale bridge damage in the field.

[0004] At present, there is a lack of research on in-situ laser additive repair methods for large bridge damage. The bridge structure is complex, and it is difficult for mechanical processing equipment to reach the designated area for damage defects in narrow positions, and the mechanical cutting effect is poor. In addition, the investment in multiple equipment during the defect repair process increases the economic and time costs. In the process of in-situ laser additive repair of steel bridges, it is necessary to face a complex external environment, and as the repair position changes, it is difficult to achieve stable protection of the protective gas in the repair area, and it is impossible to create a stable protective atmosphere, resulting in defects such as pores that affect the repair quality. Summary of the invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide an off-site in-situ laser additive repair method for steel structure plates, which solves the corrosion fatigue and other damage problems of existing steel bridges through the in-situ repair method and extends the service life of the bridge; the damaged parts are removed by laser cutting, which is more flexible and feasible while saving equipment costs; the porosity defect problem caused by the lack of protective atmosphere in the off-site environment is improved through an additive repair method combining laser remelting and laser cladding, and finally realizes the off-site in-situ laser additive repair of the damaged parts of the bridge structure.

[0006] To achieve the above object, the present invention is implemented through the following technical solutions:

[0007] An off-site in-situ laser additive repair method for a steel structure plate comprises the following steps:

[0008] 1) Determine the damage type, determine the damaged area to be repaired of the steel structure plate component, and determine the repair plan; evaluate the scope and severity of the damaged area to be repaired of the steel structure plate component, and determine the laser additive repair method and repair path planning according to the damage type and damage scope: through-repair plan or surface repair plan;

[0009] 2) For the shallow surface damage determined in step 1), the defective part is removed by laser removal process; for the deep penetration damage determined in step 1), the defective part is removed by laser cutting scheme;

[0010] 3) performing laser polishing on the surface of the damaged area to be repaired after laser cutting or laser cleaning in step 2);

[0011] 4) performing laser additive repair and filling on the damaged area to be repaired after the laser grinding treatment in step 3), and performing a layer of laser additive deposition;

[0012] 5) laser remelting the current layer of the additive repair in step 4), and ensuring that the laser remelting area completely covers the laser additive area, and performing heat treatment on the additive area;

[0013] 6) Perform the next layer of laser additive filling and repair to cover the previous layer of laser additive part;

[0014] 7) Repeat steps 4) to 6) until the laser additive completely covers the cutting area, that is, the additive repair area is filled;

[0015] 8) Perform laser remelting treatment on the surface of the additive repair area and the bonding portion between the additive repair area and the parent material to improve the quality performance of the surface of the additive repair area and the interface bonding area.

[0016] The laser additive repair method in step 1) is laser energy deposition technology (LEDE), laser wire feeding technology and other additive manufacturing technologies that use laser energy as an energy source.

[0017] In the step 1), the damage types are divided into superficial damage and deep penetration damage; the corresponding damage areas to be repaired are divided into surface repair areas and deep penetration repair areas;

[0018] Shallow surface damage refers to the defects of steel structure plate components existing on the surface and shallow surface area of ​​the steel plate, while the deep area is intact; applicable defect damage types are: friction and wear defects, surface corrosion damage, shallow crack damage; deep penetration damage refers to the defects of steel structure plate components penetrating the upper and lower surfaces of the plate; applicable defect damage types are: penetration fatigue crack damage;

[0019] The repair scheme for the shallow surface damage is the surface repair scheme: laser removes the surface damaged area, retains the deep mother material, laser polishes the corresponding area on the retained deep mother material, and then performs subsequent laser additive repair; the repair scheme for the deep penetrating damage is the penetrating repair scheme: laser cuts the defective part, laser polishes the corresponding area, and then performs subsequent laser additive repair.

[0020] In the step 2), the process parameters of laser cutting are: laser power of 600-20000W, cutting speed of 10-80mm / s, auxiliary gas pressure of 0.8-20bar, and defocusing amount of -15-17mm; the actual situation needs to be determined according to the material and thickness of the steel structure plate component.

[0021] The cutting area formed by laser cutting in the step 2) provides an additive platform for subsequent laser additive manufacturing. The cutting shape is V-shaped. The laser cutting angle and the surface should be greater than 45°, and the cutting area is as small as possible while ensuring that no damage is removed.

[0022] In the step 3), the rough area is transformed into a flat surface by laser polishing, and the surface roughness Ra is less than 12.5. The laser polishing process parameters are: spot diameter 0.06-4 mm, laser power 10-800 W, laser scanning speed 10-800 mm / s, and polishing times 1-20 times.

[0023] The steps 2) to 4) described above use the same laser system.

[0024] In the step 5), the additive repaired part is laser remelted, the depth of the laser remelting affected layer is between 0.01 and 2 mm, and the laser remelting process parameters are: spot diameter 1 to 5 mm, laser power 500 to 5000 W, and laser scanning speed 5 to 50 mm / s.

[0025] The laser remelting area in step 5) and step 8) should be expanded by 0.5 to 5 mm on the basis of complete coverage of the laser additive.

[0026] The external laser additive repair method for the steel bridge structure further includes the following steps:

[0027] 9) Using ultrasonic flaw detection equipment to perform ultrasonic flaw detection on the steel structure plate components that have been laser remelted in step 8).

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] Since the present invention adopts laser cutting and laser cleaning technology instead of traditional mechanical processing to remove the damaged parts, the cutting effect of special narrow parts is greatly improved and the damage cost of mechanical tools is reduced; at the same time, laser grinding is used for the second treatment of the processed parts to provide a good additive environment for subsequent laser additive.

[0030] Since the present invention uses a set of laser equipment system to complete the entire repair process of cutting and removing the damaged area, depositing and repairing, and post-processing, the work efficiency is improved and the cost expenditure of multiple equipment is avoided.

[0031] Since the present invention takes into account the situation that the protective gas cannot meet the laboratory requirements under field conditions and actual circumstances, the laser additive manufacturing is assisted by a laser remelting process to reflow the pores, promote the closure of the pores, and reduce pore defects. At the same time, the laser remelting process repairs the unfused defects at the junction of the laser additive manufacturing and the base material, thereby improving the quality of the repaired junction surface.

[0032] Since the present invention performs overall remelting and heat treatment in the last step of repair, the residual stress of the base material bonding part caused by the additive material is reduced; at the same time, the overall surface of the repair area and the base material area is surface treated.

[0033] In summary, the present invention can repair various types of damage to a steel bridge after long-term service, thereby restoring the use value of the steel bridge, avoiding the scrapping of the steel bridge, and reducing economic losses. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a flow chart of the present invention.

[0035] Figure 2 Schematic diagram of the repair of two solutions of the present invention.

[0036] Figure 3 This is a schematic diagram of the laser cutting range in step 2) of Example 1 of the present invention.

[0037] Figure 4 Schematic diagram of the scope of the laser additive area in step 4) and the laser remelting area in step 5) of Example 1 of the present invention.

[0038] Figure 5 It is a comparison diagram of the repaired metallographic structural defects of Example 1 of the present invention and Comparative Examples 1 and 2. DETAILED DESCRIPTION

[0039] The present invention is described in detail below with reference to the accompanying drawings.

[0040] Reference Figure 1 , a method for in-situ laser additive repair of steel structure plates in an out-of-field environment, comprising the following steps:

[0041] 1) Determine the damage type, determine the scope of the damaged area to be repaired of the steel structure plate component, and determine the laser additive repair method and repair path planning according to the damage type and damage scope;

[0042] In step 1), the laser additive repair method is laser energy deposition technology (LEDE), laser wire feeding technology, and other additive manufacturing technologies that use laser energy as an energy source;

[0043] Reference Figure 2 , the damage types are surface shallow damage and deep penetration damage, and the corresponding damage areas to be repaired are divided into surface repair areas and deep penetration repair areas;

[0044] Shallow surface damage refers to the defects of steel structure plate components existing on the surface and shallow surface area of ​​the steel plate, while the deep area is intact; the repair area is the surface repair area, and does not involve the deep parent material; the repair plan is to laser remove the surface damage area, retain the deep parent material, and directly perform laser additive repair on the retained deep parent material; the applicable defect damage types are: friction and wear defects, surface corrosion damage, shallow crack damage, etc.

[0045] Deep penetration damage refers to the defects of steel structure plate components that have penetrated the upper and lower surfaces of the plate; the repair area is the deep penetration repair area, and the parent material is repaired through; the repair plan is laser cutting of the defective part, followed by laser additive repair; the applicable defect damage types are: through fatigue crack damage, etc.

[0046] 2) Laser cutting or laser removal is performed on the damaged area to be repaired determined in step 1); the cutting area formed by laser cutting provides an additive platform for subsequent laser additives, the cutting shape is V-shaped, the laser cutting angle and the surface should be greater than 45°, and the cutting area is as small as possible while ensuring the removal of the damage;

[0047] The process parameters of laser cutting are: laser power 600~20000W, cutting speed 10~80mm / s, auxiliary gas pressure 0.8~20bar, defocusing amount -15~17mm; the actual situation needs to be determined according to the material, thickness and other process parameters of the steel structure plate components;

[0048] 3) performing laser polishing on the surface of the damaged area to be repaired after laser cutting or laser cleaning in step 2);

[0049] The purpose of laser grinding is to remove surface quality problems such as slag, burrs and spatter on the surface of the damaged area to be repaired, and transform the rough area into a flat surface with a surface roughness Ra<12.5, creating a good additive repair environment; laser grinding process parameters: spot diameter 0.06~4mm, laser power 10~800W, laser scanning speed 10~800mm / s, grinding times 1~20 times;

[0050] 4) performing laser additive repair and filling on the damaged area to be repaired after the laser grinding treatment in step 3), and performing a layer of laser additive deposition;

[0051] 5) Laser remelting the current layer of the additive repair in step 4), and ensuring that the laser remelting area completely covers the laser additive area, reducing the repair defects in the additive area, and performing heat treatment on the additive area;

[0052] The purpose of laser remelting the additive repair part is to close the pore defects generated in the laser additive part due to the external field environment problem in step 4) and promote the floating and overflow of the pore defects; the depth of the laser remelting affected layer is between 0.01 and 2 mm, ensuring a good closing effect on the pore defects of the laser additive part; laser remelting process parameters: spot diameter 1 to 5 mm, laser power 500 to 5000 W, laser scanning speed 5 to 50 mm / s;

[0053] 6) Perform the next layer of laser additive filling and repair to cover the previous layer of laser additive part;

[0054] 7) Repeat steps 4) to 6) until the laser additive completely covers the cutting area, that is, the additive repair area is filled;

[0055] 8) Perform laser remelting treatment on the surface of the additive repair area and the bonding portion between the additive repair area and the parent material to improve the quality performance of the surface of the additive repair area and the interface bonding area.

[0056] The steps 2) to 4) described above use the same laser system.

[0057] The laser remelting area in step 5) and step 8) should be expanded by 0.5 to 5 mm on the basis of completely covering the laser additive material, to ensure a defect-free and good bonding between the laser additive material and the base material, and to perform post-processing on the bonding interface.

[0058] The external laser additive repair method for the steel bridge structure further includes the following steps:

[0059] 9) Using ultrasonic flaw detection equipment to perform ultrasonic flaw detection on the steel structure plate components that have been laser remelted in step 8).

[0060] The present invention is described in detail below with reference to the embodiments. In the embodiment, the Q345 bridge steel structure is repaired by in-situ laser powder feeding cladding. The in-situ laser additive repair method of the present invention can be applied to other metals at the same time.

[0061] Example 1: Taking an orthotropic bridge steel structure plate member with a thickness of 10 mm as an example, through fatigue cracks often occur at the portion where the top plate is connected to the U rib due to the action of alternating loads.

[0062] Reference Figure 2 , a method for in-situ laser additive repair of a steel bridge structure in an outdoor field, comprising the following steps:

[0063] 1) According to the actual situation of the steel structure plate component, it is determined that the damage type of the steel structure plate component is through fatigue crack damage, and the damage degree is that it has penetrated the parent steel plate. The laser additive repair scheme is to select laser cutting first and then laser additive;

[0064] 2) Laser cutting is performed on the damaged area to be repaired. The position of the laser head is controlled by the robot. The laser cutting range is as follows: Figure 3 As shown, the cutting area formed by laser cutting provides an additive platform for subsequent laser additives. The cutting shape is V-shaped. The laser cutting angle and the surface should be greater than 45°, and the cutting area should be as small as possible while ensuring the removal of damage.

[0065] The process parameters of laser cutting are: laser power 4000W, cutting speed 15mm / s, auxiliary gas (oxygen) pressure 16bar, defocusing amount -6mm;

[0066] 3) Use a laser beam with lower energy to perform laser polishing on the rough surface after laser cutting, polish the slag, burrs and spatter remaining in the repair area after laser cutting and the rough surface generated by the scanning strategy to a smooth surface roughness Ra <12.5, creating a good additive repair environment;

[0067] Laser polishing processing parameters: spot diameter 1mm, laser power 350W, laser scanning speed 200mm / s, polishing times 10 times;

[0068] 4) Perform the first layer of laser additive repair and filling on the damaged area to be repaired. The laser additive parameters are as follows: laser power 1000W, powder feeding amount 6g / min, spot diameter 2mm, scanning speed 10mm / s;

[0069] 5) Laser remelting is performed on the current layer of the additive repair. The depth of the laser remelting affected layer is between 0.01 and 2 mm. The laser remelting area completely covers the laser additive area and the area where the laser additive and the base material meet. Figure 4 As shown, the unfused defects of pores in the additive repair layer are reduced, and the additive area is heat treated to a certain extent to slow down the cooling rate of austenite and improve the plastic properties of the additive repair part. The laser remelting process parameters are: laser power 2000W, spot diameter 2mm, scanning speed 10mm / s;

[0070] 6) Perform the next layer of laser additive filling and repair to cover the previous layer of laser additive part;

[0071] 7) Repeat steps 4)-6) to perform the next laser additive filling repair. Each layer of the laser additive part should be completely combined with the base material, and the laser remelting part should completely cover the laser additive part and the bonding interface. The range can be appropriately expanded until the laser additive repair part is filled;

[0072] 8) Perform laser remelting treatment on the upper and lower surfaces of the laser additive repair area, covering the additive area, the area where the additive and base material are combined, and the adjacent base material area; the laser remelting process parameters are the same as step five; perform laser remelting treatment on the surface of the treated repair area and the part where the additive repair area and base material are combined to improve the quality performance of the repair area surface and interface bonding area.

[0073] Finally, the repair quality of the laser additive repair area was good, the repair interface was well bonded, the repair area was dense, and there were no obvious pore crack defects; the parent material part had no thermal cracks and other defects. The damaged part of the steel plate was effectively repaired.

[0074] Example 2: Compared with Example 1, when the thickness of the repaired steel plate is 25 mm, the process parameters of laser cutting in step 2) are: laser power of 12000 W, cutting speed of 20 mm / s, auxiliary gas (oxygen) pressure of 1.4 bar, and defocusing amount of +17 mm; the process parameters of laser polishing in step 3) are: spot diameter of 2 mm, laser power of 800 W, laser scanning speed of 50 mm / s, and polishing times of 1 time; the process parameters of laser remelting in step 5) are: laser power of 3000 W, spot diameter of 5 mm, and scanning speed of 5 mm / s; the rest of the process operations are consistent with those in Example 1. The repair effect is consistent with that in Example 1, and the damaged part of the steel plate is effectively and well repaired.

[0075] Example 3: Compared with Example 1, when the thickness of the repaired steel plate is 25 mm, the process parameters of laser cutting in step 2) are: laser power is 20000 W, cutting speed is 40 mm / s, auxiliary gas (air) pressure is 12 bar, and defocusing amount is -15 mm; the process parameters of laser polishing in step 3) are: spot diameter is 3 mm, laser power is 300 W, laser scanning speed is 10 mm / s, and polishing times are 6 times; the process parameters of laser remelting in step 5) are: laser power is 5000 W, spot diameter is 2 mm, and scanning speed is 50 mm / s; the rest of the process operations are consistent with Example 1. The repair effect is consistent with that in Example 1, and the damaged part of the steel plate is effectively and well repaired.

[0076] Example 4: Compared with Example 1, when the thickness of the repaired steel plate is 3 mm, the process parameters of step 2) laser cutting are: laser power 600 W, cutting speed 10 mm / s, auxiliary gas (oxygen) pressure 0.8 bar, defocusing amount +1.5 mm; step 3) laser grinding process parameters: spot diameter 0.06 mm, laser power 10 W, laser scanning speed 300 mm / s, grinding times 20 times; step 5) laser remelting process parameters: laser power 500 W, spot diameter 1 mm, scanning speed 5 mm / s; the rest of the process operations are consistent with Example 1. The repair effect is consistent with that of Example 1, and the damaged part of the steel plate is effectively and well repaired.

[0077] Example 5: Compared with Example 1, when the thickness of the repaired steel plate is 3mm, the process parameters of laser cutting in step 2) are: laser power is 2000W, cutting speed is 80mm / s, auxiliary gas (air) pressure is 20bar, and defocusing amount is -4mm; the process parameters of laser polishing in step 3) are: spot diameter is 1.5mm, laser power is 50W, laser scanning speed is 800mm / s, and polishing times are 5 times; the process parameters of laser remelting in step 5) are: laser power is 1000W, spot diameter is 2mm, and scanning speed is 10mm / s; the rest of the process operations are consistent with Example 1. The repair effect is consistent with that of Example 1, and the damaged part of the steel plate is effectively and well repaired.

[0078] Comparative Example 1: Compared with Example 1, the overall surface laser remelting process was not performed after the repair was completed, and the remaining process operations were consistent with Example 1.

[0079] Comparative Example 2: Compared with Example 1, during the laser additive process, laser additive deposition repair is adopted, without interlayer laser remelting and surface laser remelting process treatment, and the other process operations are consistent with Example 1.

[0080] Comparison of metallographic defects in the laser additive repaired area after repair in Example 1 and Comparative Examples 1 and 2 Figure 5 As shown, after surface laser remelting, the unfused defects near the surface of Example 1 were closed, and the repaired area was dense as a whole without obvious defects; in Comparative Example 1, since the surface remelting and pore closing treatment was not performed, unfused defects appeared in the near-surface area; in Comparative Example 2, the number of defects in the repaired area was large and the distribution range was large. This shows that interlayer laser remelting and surface laser remelting are crucial to the repair quality and are important steps of the method of the present invention.

Claims

1. An in-situ laser additive repair method for steel structure panels, characterized in that: The following steps are involved: 1) Determine the damage type, determine the damaged area to be repaired of the steel structure plate component, and determine the repair plan; Assess the scope and severity of the damaged area to be repaired on the steel structure plate components, and determine the laser additive repair method and repair path planning according to the damage type and damage scope: through-repair plan or surface repair plan; 2) For the shallow surface damage determined in step 1), the defective part is removed by laser removal process; for the deep penetration damage determined in step 1), the defective part is removed by laser cutting scheme; 3) performing laser polishing on the surface of the damaged area to be repaired after laser cutting or laser cleaning in step 2); 4) performing laser additive repair and filling on the damaged area to be repaired after the laser grinding treatment in step 3), and performing a layer of laser additive deposition; 5) laser remelting the current layer of the additive repair in step 4), and ensuring that the laser remelting area completely covers the laser additive area, and performing heat treatment on the additive area; 6) Perform the next layer of laser additive filling and repair to cover the previous layer of laser additive part; 7) Repeat steps 4) to 6) until the laser additive completely covers the cutting area, that is, the additive repair area is filled; 8) Perform laser remelting treatment on the surface of the additive repair area and the bonding portion between the additive repair area and the parent material to improve the quality performance of the surface of the additive repair area and the interface bonding area.

2. The method according to claim 1, characterized in that: The laser additive repair method in step 1) is laser energy deposition technology (LEDE), laser wire feeding technology and other additive manufacturing technologies that use laser energy as an energy source.

3. The method according to claim 1, characterized in that: In the step 1), the damage types are divided into superficial damage and deep penetration damage; the corresponding damage areas to be repaired are divided into surface repair areas and deep penetration repair areas; Shallow surface damage refers to the situation where the defects of steel structure plate components exist on the surface and shallow surface area of ​​the steel plate, while the deep area is intact; Applicable defect damage types are: friction and wear defects, surface corrosion damage, shallow crack damage; deep penetration damage refers to the defects of steel structure plate components that have penetrated the upper and lower surfaces of the plate; applicable defect damage types are: through fatigue crack damage; The repair scheme for the shallow surface damage is the surface repair scheme: laser removes the surface damaged area, retains the deep mother material, laser polishes the corresponding area on the retained deep mother material, and then performs subsequent laser additive repair; the repair scheme for the deep penetrating damage is the penetrating repair scheme: laser cuts the defective part, laser polishes the corresponding area, and then performs subsequent laser additive repair.

4. The method according to claim 1, characterized in that: In the step 2), the process parameters of laser cutting are: laser power of 600 to 20,000 W, cutting speed of 10 to 80 mm / s, auxiliary gas pressure of 0.8 to 20 bar, and defocusing amount of -15 to 17 mm.

5. The method according to claim 1, characterized in that: The cutting area formed by laser cutting in the step 2) provides an additive platform for subsequent laser additive manufacturing. The cutting shape is V-shaped. The laser cutting angle and the surface should be greater than 45°, and the cutting area is as small as possible while ensuring that no damage is removed.

6. The method according to claim 1, characterized in that: In the step 3), the rough area is transformed into a flat surface by laser polishing, and the surface roughness Ra is less than 12.

5. The laser polishing parameters are as follows: the spot diameter is 0.06-4 mm, the laser power is 10-800 W, the laser scanning speed is 10-800 mm / s, and the polishing times are 1-20 times.

7. The method according to claim 1, characterized in that: The steps 2) to 4) described above use the same laser system.

8. The method according to claim 1, characterized in that: In the step 5), the additive repaired part is laser remelted, the depth of the laser remelting affected layer is between 0.01 and 2 mm, and the laser remelting process parameters are: spot diameter 1 to 5 mm, laser power 500 to 5000 W, and laser scanning speed 5 to 50 mm / s.

9. The method according to claim 1, characterized in that: The laser remelting area in step 5) and step 8) should be expanded by 0.5 to 5 mm on the basis of complete coverage of the laser additive.

10. The method according to claim 1, characterized in that: The steel bridge structure off-site laser additive repair method also includes the following steps: 9) using ultrasonic flaw detection equipment to perform ultrasonic flaw detection on the steel structure plate components that have undergone laser remelting treatment in step 8).

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