Wet-type high-power combined laser cleaning method suitable for heavily-corroded steel structure

Abstract

The invention provides a wet-type high-power combined laser cleaning method suitable for a heavily-corroded steel structure. S1, measuring the thickness of a rust layer on the steel surface of the steel structure; s2, liquid is sprayed to the surface of the to-be-cleaned area of the steel structure to form a liquid film, and the liquid film is used for increasing the laser absorptivity of the surface of the rust layer; s3, the to-be-cleaned area is preliminarily cleaned through continuous laser, the rust layer is made to be fluffy and stripped through the thermal expansion effect, and the thickness of the rust layer is reduced to be not larger than the target threshold value of preliminary cleaning; s4, performing fine cleaning by using pulse laser to accurately remove a residual stubborn rust layer; s5, the to-be-cleaned area is washed; the device can effectively remove a rust layer on the surface of the steel, reduce plasma and smoke dust generated in the laser cleaning process, ensure the safety and high efficiency of the cleaning process, adopt the combination of continuous laser and pulse laser, clean in stages, effectively improve the cleaning efficiency, and reduce thermal damage to the surface of the steel.

Description

Technical Field

[0001] The invention relates to the technical field of laser application, in particular to a wet high-power combined laser cleaning method suitable for heavily corroded steel structures. Background Art

[0002] Steel is a widely used structural material in construction projects. As its use time increases, it often faces oxidation and corrosion problems. Especially in humid, marine climates or chemical corrosion environments, rust layers, rust spots and other corrosive products are easily formed on the surface of steel, which seriously affect the mechanical properties, durability and safety of the structure. In construction projects such as bridges and reinforced concrete components, steel corrosion will not only lead to a decrease in material strength, but may also have a negative impact on coating adhesion, welding quality, etc., thereby increasing the cost of structural maintenance and even posing a safety hazard. Therefore, how to efficiently and accurately remove corrosive products on the surface of steel and restore the surface quality of steel is an important issue that needs to be solved in construction projects.

[0003] At present, the construction industry generally adopts traditional cleaning methods, such as chemical rust removal, sandblasting and electrolytic cleaning. Although these methods can remove corrosive substances, they still have many shortcomings. Chemical cleaning may not only cause secondary pollution, but also cause certain harm to the environment and operators; sandblasting cleaning is prone to mechanical damage to the metal surface; and electrolytic cleaning is usually slow and the cleaning effect is difficult to control uniformly. These problems make it difficult for traditional cleaning methods to meet the requirements of high efficiency, environmental protection and precision in large-scale industrial applications.

[0004] As an emerging surface treatment technology, laser cleaning technology has been gradually applied to cleaning and rust removal of metal surfaces due to its non-contact, strong controllability, and good cleaning effect. Through the high energy density of the pulsed laser beam, laser cleaning can effectively remove the rust layer and corrosion products on the surface of steel in a short time while avoiding physical damage to the substrate. However, the current laser cleaning technology still faces some challenges, especially in the application of high-power lasers. How to effectively control the laser energy distribution and avoid damage to the steel surface due to local overheating is still a key issue in the development of the technology.

[0005] To overcome this problem, a combined laser cleaning method came into being. By using laser beams of different powers and characteristics at the same time, a multi-level cleaning effect can be achieved, improving cleaning efficiency and ensuring surface quality. In particular, the combination of continuous laser and nanosecond pulse laser can quickly remove coarse corrosion products on the surface of corroded steel, while the Gaussian laser performs fine cleaning on the surface to ensure the uniformity of the cleaning effect. The two laser heads work simultaneously and can work together efficiently during the cleaning process, each playing its own advantages. The continuous laser provides powerful energy to quickly remove thicker rust, while the Gaussian laser can accurately remove residual contaminants and avoid overheating or local damage.

[0006] The present invention proposes a method for laser cleaning of corroded steel. By using continuous laser and nanosecond pulse laser for cleaning, the corrosion layer and oxide on the surface of the steel can be removed quickly and efficiently, and the SA2 cleaning standard can be finally achieved. The method reduces heat accumulation, avoids overheating damage to the metal surface, and improves cleaning efficiency and surface quality by optimizing laser power, pulse width, frequency and scanning trajectory. The technology has broad application prospects, and is particularly suitable for corrosion removal and protection of steel surfaces in construction projects. Summary of the invention

[0007] The present invention proposes a wet high-power combined laser cleaning method suitable for heavily corroded steel structures. By combining liquid film and laser cleaning technology, the rust layer on the surface of the steel can be effectively removed, while reducing the plasma and smoke generated during the laser cleaning process, ensuring the safety and efficiency of the cleaning process. The method uses a combination of continuous laser and pulsed laser to perform cleaning in stages, which can effectively improve the cleaning efficiency and reduce thermal damage to the steel surface. The laser cleaning method provided by the present invention is suitable for steel or metal surfaces with a rust layer thickness of at least 150μm.

[0008] A wet high-power combined laser cleaning method applicable to heavily corroded steel structures comprises the following steps; Step S1, measuring the thickness of the rust layer on the surface of the steel structure steel; Step S2, spraying liquid on the surface of the area to be cleaned of the steel structure to form a liquid film, wherein the liquid film is used to increase the absorption rate of the rust layer surface to the laser; Step S3, using a continuous laser to perform preliminary cleaning on the area to be cleaned, and through the effect of thermal expansion, the rust layer is fluffy and peeled off, so that the thickness of the rust layer is reduced to no more than the target threshold of the preliminary cleaning; Step S4: using pulsed laser for fine cleaning to accurately remove the remaining stubborn rust layer; Step S5: rinse the area to be cleaned.

[0009] In step S1, the rust layer is a corrosion rust layer, and the thickness of the rust layer is measured using a coating thickness gauge.

[0010] In step S2, deionized water is sprayed on the surface of the steel material to be cleaned to form a liquid film. In step S3, the deionized water absorbs most of the energy of the continuous laser so that the remaining thin rust layer will not overheat and damage the substrate. In step S4, a nanosecond pulse laser is used to act on the thin rust layer at the bottom of the rust layer to cause it to vaporize, resonate and peel off, thereby achieving the goal of cleaning and removing the rust layer without damaging the substrate.

[0011] In step S2, the thickness of the liquid film is less than or equal to 1 mm.

[0012] In step S2, the liquid film is also used to reduce the generation of plasma and smoke, and to constrain the movement trajectory of the smoke, so as to ensure the safety and cleanliness of the cleaning process.

[0013] In step S3, the continuous laser power is 1000W to 3000W, the scanning speed is 8000mm / s to 10000mm / s, and the line spacing is 0.08mm to 0.12mm.

[0014] In step S3, the thickness of the rust layer after continuous laser cleaning is no more than 50 μm; in step S3, if the thickness of the rust layer is not reduced to below the target threshold of the preliminary cleaning, the continuous laser is repeatedly used to perform preliminary cleaning on the area to be cleaned, and steps S1 and S2 are repeated before each cleaning to ensure the presence of the liquid film and maximize the laser cleaning effect. If the cleaning speed needs to be further accelerated, starting from the second continuous laser cleaning, the area to be cleaned is purged with compressed gas to remove the fluffy and cracked rust layer during the last cleaning.

[0015] In step S4, the pulse laser power is 300W to 1000W, the pulse width is 100ns to 300ns, the frequency is 200kHz to 4000kHz, the scanning speed is 8000mm / s to 10000mm / s, and the line spacing is 0.08mm to 0.12mm.

[0016] In step S4, the pulse laser is a nanosecond pulse laser, and the number of times the area to be cleaned is cleaned by the nanosecond pulse laser is one, two or more times, and the impact of cleaning on the substrate is reduced by multiple nanosecond pulse laser cleanings, and the cleaning quality is improved by multiple nanosecond pulse laser cleanings; When the nanosecond pulse laser is used for cleaning more than twice, the power of the first nanosecond pulse laser is 500-1000W, the scanning speed is 8000-1000mm / s, the line spacing is 0.08-0.12mm, and the power of the nanosecond pulse laser after the first pass is 300-500W, and the scanning speed is 8000-10000mm / s.

[0017] In step S5, the area to be cleaned is rinsed with deionized water to remove possible remaining rust fragments, dirt and liquid residues in the cleaning process to ensure the cleaning effect.

[0018] The present invention provides a wet laser cleaning method suitable for cleaning rust layer on the surface of steel, which aims to effectively remove the rust layer on the surface of steel by combining liquid film and laser cleaning technology, while reducing the plasma and smoke generated during the laser cleaning process to ensure the safety and efficiency of the cleaning process. The method combines continuous laser with pulsed laser and performs cleaning in stages, which can effectively improve the cleaning efficiency and reduce thermal damage to the surface of steel. The laser cleaning method provided by the present invention is suitable for steel or metal surfaces with a rust layer thickness of at least 150μm.

[0019] The present invention proposes a method for laser cleaning of corroded steel. By using continuous laser and nanosecond pulse laser for cleaning, the corrosion layer and oxide on the surface of the steel can be removed quickly and efficiently, and the SA2 cleaning standard can be finally achieved. The method reduces heat accumulation, avoids overheating damage to the metal surface, and improves cleaning efficiency and surface quality by optimizing laser power, pulse width, frequency and scanning trajectory. The technology has broad application prospects, and is particularly suitable for corrosion removal and protection of steel surfaces in construction projects.

[0020] Compared with the prior art, the present invention has the following advantages: 1 The wet laser cleaning method of the present invention can effectively reduce the smoke and harmful gases generated during the laser paint stripping process by spraying a liquid film, thereby avoiding the harm to human health and the environment that may be caused by traditional dry laser cleaning. The liquid film not only improves the absorption rate of the laser and reduces the thermal damage of the laser to the metal surface, but also significantly reduces the pollutant emissions during the cleaning process by inhibiting the generation of plasma and restricting the diffusion of smoke, ensuring that the cleaning process is more environmentally friendly and sustainable.

[0021] 2 By rationally combining the working characteristics of continuous laser and pulsed laser, the present invention can accurately control energy input, reduce excessive consumption and unnecessary energy waste. Continuous laser is used to quickly remove rust, while pulsed laser is used to deal with stubborn pollution that is difficult to remove, avoiding the high energy consumption of repeated cleaning. At the same time, the wet cleaning process reduces the laser intensity requirement, improves the utilization efficiency of resources, and ensures the environmental protection and economy of the laser cleaning method. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments: Attached Figure 1 It is a schematic flow chart of a laser cleaning method applicable to a corroded rust layer of the present invention; Attached Figure 2 is a schematic diagram of the surface morphology of the corroded steel plate before cleaning; Attached Figure 3 This is a schematic diagram of the surface morphology after continuous laser cleaning; Attached Figure 4This is a schematic diagram of the surface morphology after two consecutive laser cleanings; Attached Figure 5 It is a schematic diagram of the surface morphology after cleaning by the laser cleaning method provided by the present invention. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention. It is understood that the drawings are only provided for reference and explanation, and are not used to limit the present invention.

[0024] As shown in the figure, a wet high-power combined laser cleaning method suitable for severely corroded steel structures includes the following steps; Step S1, measuring the thickness of the rust layer on the surface of the steel structure steel; Step S2, spraying liquid on the surface of the area to be cleaned of the steel structure to form a liquid film, wherein the liquid film is used to increase the absorption rate of the rust layer surface to the laser; Step S3, using a continuous laser to perform preliminary cleaning on the area to be cleaned, and through the effect of thermal expansion, the rust layer is fluffy and peeled off, so that the thickness of the rust layer is reduced to no more than the target threshold of the preliminary cleaning; Step S4: using pulsed laser for fine cleaning to accurately remove the remaining stubborn rust layer; Step S5: rinse the area to be cleaned.

[0025] In step S1, the rust layer is a corrosion rust layer, and the thickness of the rust layer is measured using a coating thickness gauge.

[0026] In step S2, deionized water is sprayed on the surface of the steel material to be cleaned to form a liquid film. In step S3, the deionized water absorbs most of the energy of the continuous laser so that the remaining thin rust layer will not overheat and damage the substrate. In step S4, a nanosecond pulse laser is used to act on the thin rust layer at the bottom of the rust layer to cause it to vaporize, resonate and peel off, thereby achieving the goal of cleaning and removing the rust layer without damaging the substrate.

[0027] In step S2, the thickness of the liquid film is less than or equal to 1 mm.

[0028] In step S2, the liquid film is also used to reduce the generation of plasma and smoke, and to constrain the movement trajectory of the smoke, so as to ensure the safety and cleanliness of the cleaning process.

[0029] In step S3, the continuous laser power is 1000W to 3000W, the scanning speed is 8000mm / s to 10000mm / s, and the line spacing is 0.08mm to 0.12mm.

[0030] In step S3, the thickness of the rust layer after continuous laser cleaning is no more than 50 μm; in step S3, if the thickness of the rust layer is not reduced to below the target threshold of the preliminary cleaning, the continuous laser is repeatedly used to perform preliminary cleaning on the area to be cleaned, and steps S1 and S2 are repeated before each cleaning to ensure the presence of the liquid film and maximize the laser cleaning effect. If the cleaning speed needs to be further accelerated, starting from the second continuous laser cleaning, the area to be cleaned is purged with compressed gas to remove the fluffy and cracked rust layer during the last cleaning.

[0031] In step S4, the pulse laser power is 300W to 1000W, the pulse width is 100ns to 300ns, the frequency is 200kHz to 4000kHz, the scanning speed is 8000mm / s to 10000mm / s, and the line spacing is 0.08mm to 0.12mm.

[0032] In step S4, the pulse laser is a nanosecond pulse laser, and the number of times the area to be cleaned is cleaned by the nanosecond pulse laser is one, two or more times, and the impact of cleaning on the substrate is reduced by multiple nanosecond pulse laser cleanings, and the cleaning quality is improved by multiple nanosecond pulse laser cleanings; When the nanosecond pulse laser is used for cleaning more than twice, the power of the first nanosecond pulse laser is 500-1000W, the scanning speed is 8000-1000mm / s, the line spacing is 0.08-0.12mm, and the power of the nanosecond pulse laser after the first pass is 300-500W, and the scanning speed is 8000-10000mm / s.

[0033] In step S5, the area to be cleaned is rinsed with deionized water to remove possible remaining rust fragments, dirt and liquid residues in the cleaning process to ensure the cleaning effect.

[0034] Example: This example includes the following steps: First, the thickness δ of the rust layer on the surface of the steel material to be cleaned is measured, wherein the thickness of the rust layer is at least 150 μm, so as to determine the required laser power and cleaning parameters.

[0035] Spray liquid on the surface of the area to be cleaned to form a liquid film with a thickness of less than or equal to 1mm. The function of this liquid film is to enhance the absorption rate of the steel surface to the laser, reduce the heat transfer between the laser and the rust layer, and reduce the generation of plasma and smoke. The presence of liquid can also constrain the movement trajectory of smoke, ensuring that the cleaning process is more environmentally friendly.

[0036] A continuous laser with a power of 1000W to 3000W is used for preliminary cleaning, with a laser scanning speed of 8000mm / s to 10000mm / s and a line spacing of 0.08mm to 0.12mm. Through the thermal expansion effect, the continuous laser makes the rust layer fluffy and peeled off, and the thickness of the rust layer after cleaning is no more than 50μm. This step efficiently removes most of the oxides and creates conditions for subsequent fine cleaning.

[0037] In cases where multiple cleanings are required, the liquid film needs to be re-sprayed before each cleaning and the continuous laser cleaning is continued to ensure that each round of cleaning can further remove the rust layer until it is completely removed.

[0038] Use pulsed laser for fine cleaning, with pulsed laser power of 300W to 1000W, pulse width of 100ns to 300ns, frequency of 200KHz to 4000KHz, scanning speed of 6000mm / s to 10000mm / s, and line spacing of 0.08mm to 0.12mm. Pulsed laser can remove the remaining stubborn rust layer and ensure that the steel surface is not damaged.

[0039] See also Figure 1 , Figure 1 This is a flow chart of the laser cleaning method of this example, which provides a laser cleaning method suitable for corroded steel, where the rust layer thickness is at least 150μm, and the laser cleaning method includes the following steps.

[0040] (1) Using a coating thickness gauge, the paint thickness δ is measured to be 167 μm (2) Spray deionized water on the surface of the steel to be cleaned, forming a deionized water liquid film of about 500 μm on the surface. (3) The area to be cleaned is cleaned by continuous laser, wherein the continuous laser power is 1000-3000w, the scanning speed is 8000-10000mm / s, and the line spacing is 0.08-0.12mm. By setting the continuous laser within the parameter range, the rust layer on the surface expands due to heat and becomes fluffy and peeled off. The thickness of the rust layer after cleaning is not more than 50μm.

[0041] (4) The area to be cleaned is cleaned by a nanosecond pulse laser, wherein the power of the nanosecond pulse laser is 300W to 1000W, the pulse width is 100ns to 300ns, the frequency is 200KHz to 4000KHz, the scanning speed is 6000mm / s to 10000mm / s, and the line spacing is 0.08mm to 0.12mm. The remaining rust layer is removed by gasification and vibration by setting the pulse laser within the parameter range.

[0042] When continuous laser cleaning is performed, the laser focus position is adjusted to between 20-50mm above the workpiece. Compared with laser cleaning with a focus position less than 20mm, it can avoid damage to the substrate due to excessive energy during cleaning, and can also increase the cleaning range by expanding the light spot to improve cleaning efficiency. Compared with laser cleaning with a focus position greater than 50mm, the cleaning quality is relatively high.

[0043] The area to be cleaned may be cleaned once, twice or more than twice by using nanosecond pulse laser for cleaning. Cleaning by using nanosecond pulse laser for multiple times can relatively reduce the impact of cleaning on the substrate, and the cleaning quality by using nanosecond pulse laser for multiple times is higher than that by using nanosecond pulse laser for cleaning once.

[0044] The nanosecond pulse laser power of the first pass is 500-1000W, the scanning speed is 8000-1000mm / s, and the line spacing is 0.08-0.12mm. The nanosecond pulse laser power after the first pass is 300-500W, and the scanning speed is 8000-10000mm / s.

[0045] The present invention utilizes the high energy density of continuous laser to make the surface rust layer expand due to heat, thereby making it fluffy and peeled off. Since deionized water absorbs most of the energy, the remaining rust layer will not overheat and damage the substrate. Nanosecond pulse laser is then used to act on the thinner rust layer at the bottom layer, causing it to vaporize, resonate and peel off, thereby achieving non-destructive removal of the substrate.

[0046] Compared with using a single continuous laser for cleaning, the high energy density of the continuous laser may cause damage to the substrate; the comparison between using a single pulse laser for cleaning and the cleaning method of the present invention can be obtained by comparing the following Example 1 and Example 2.

[0047] Embodiment 1: Example 1: Cleaning was performed using a 1500W continuous laser for 2 times, and the sample was placed on a laboratory bench.

[0048] The cleaning parameters of the pulse laser for the first pass were set as follows: continuous laser power of 1500 W, scanning speed of 8000 mm / s, frequency of 100 kHz, pulse width of 200 ns, and line spacing of 0.08 mm.

[0049] The laser cleaning parameters for the second cleaning pass were set as follows: pulse laser power of 1500 W, scanning speed of 10000 mm / s, frequency of 10 KHz, pulse width of 100 ns, and line spacing of 0.08 mm.

[0050] The cleaning method is galvanometer platform scanning or handheld cleaning. During the cleaning process, an external dust extraction device is used to recover the generated smoke and dust particles.

[0051] When continuous laser cleaning is used alone, the steel is cleaned twice by laser cleaning, and the surface of the substrate is thoroughly cleaned. After the first scan, the surface of the substrate is oxidized and has a blue luster. After the second scan, the surface of the substrate is oxidized more and has a black luster.

[0052] After continuous laser scanning, Figure 2 As shown, after scanning twice, Figure 3 shown.

[0053] Embodiment 2: Example 2 is an example of cleaning using the laser cleaning method provided by the present invention, specifically using a combination of a 2000W continuous laser and a 500W nanosecond pulse laser for cleaning, and the sample is placed on a laboratory table.

[0054] The laser is cleaned by continuous laser, and the parameters are set as follows: laser power is 2000W, scanning speed is 10000mm / s, and line spacing is 0.12mm Compressed air is used to blow off the fluffy and cracked oxide scale on the surface of the substrate after continuous laser cleaning.

[0055] Use pulse laser for cleaning twice: the parameters of the first pass are set as pulse laser power of 500W, scanning speed of 10000mm / s, frequency of 100KHz, pulse width of 200ns, and line spacing of 0.12mm; the parameters of the second pass are set as pulse laser power of 300W, scanning speed of 10000mm / s, frequency of 400kHz, pulse width of 200ns, and filling line spacing of 0.1mm.

[0056] The cleaning method is galvanometer platform scanning or handheld cleaning. After continuous laser and pulse laser combined cleaning, the rust layer on the substrate surface is thoroughly cleaned. The surface shows the original morphology of the substrate, the metallic luster of the substrate, and no streaks. Compared with pulse laser cleaning alone, its cleaning efficiency is significantly improved.

[0057] Figure 2 This is the overall morphology of the rust layer before cleaning in Example 2. Figure 5 This is the overall morphology of the substrate after cleaning in Example 2.

[0058] Some features of the present invention are described in different embodiments for clarity of description, however, these features may also be described in combination in a single embodiment. Conversely, some features of the present invention are described in only a single embodiment for brevity, however, these features may also be described in different embodiments alone or in any suitable combination.

[0059] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A wet high-power combined laser cleaning method suitable for severely corroded steel structures, characterized by: The steps include: Step S1, measuring the thickness of the rust layer on the surface of the steel structure steel; Step S2, spraying liquid on the surface of the area to be cleaned of the steel structure to form a liquid film, wherein the liquid film is used to increase the absorption rate of the rust layer surface to the laser; Step S3, using a continuous laser to perform preliminary cleaning on the area to be cleaned, and through the effect of thermal expansion, the rust layer is fluffy and peeled off, so that the thickness of the rust layer is reduced to no more than the target threshold of the preliminary cleaning; Step S4: using pulsed laser for fine cleaning to accurately remove the remaining stubborn rust layer; Step S5: rinse the area to be cleaned.

2. The wet high-power combined laser cleaning method for severely corroded steel structures according to claim 1 is characterized in that: In step S1, the rust layer is a corrosion rust layer, and the thickness of the rust layer is measured using a coating thickness gauge.

3. The wet high-power combined laser cleaning method for severely corroded steel structures according to claim 1 is characterized in that: In step S2, deionized water is sprayed on the surface of the steel material to be cleaned to form a liquid film. In step S3, the deionized water absorbs most of the energy of the continuous laser so that the remaining thin rust layer will not overheat and damage the substrate. In step S4, a nanosecond pulse laser is used to act on the thin rust layer at the bottom of the rust layer to cause it to vaporize, resonate and peel off, thereby achieving the goal of cleaning and removing the rust layer without damaging the substrate.

4. The wet high-power combined laser cleaning method for severely corroded steel structures according to claim 1 is characterized in that: In step S2, the thickness of the liquid film is less than or equal to 1 mm.

5. The wet high-power combined laser cleaning method for severely corroded steel structures according to claim 1 is characterized in that: In step S2, the liquid film is also used to reduce the generation of plasma and smoke, and to constrain the movement trajectory of the smoke to ensure the safety and cleanliness of the cleaning process.

6. The wet high-power combined laser cleaning method for severely corroded steel structures according to claim 1 is characterized in that: In step S3, the continuous laser power is 1000W to 3000W, the scanning speed is 8000mm / s to 10000mm / s, and the line spacing is 0.08mm to 0.12mm.

7. The wet high-power combined laser cleaning method for severely corroded steel structures according to claim 1, characterized in that: In step S3, the thickness of the rust layer after continuous laser cleaning is no more than 50 μm; in step S3, if the thickness of the rust layer is not reduced to below the target threshold of the preliminary cleaning, the continuous laser is repeatedly used to perform preliminary cleaning on the area to be cleaned, and steps S1 and S2 are repeated before each cleaning to ensure the presence of the liquid film and maximize the laser cleaning effect. If the cleaning speed needs to be further accelerated, starting from the second continuous laser cleaning, the area to be cleaned is purged with compressed gas to remove the fluffy and cracked rust layer during the last cleaning.

8. The wet high-power combined laser cleaning method for severely corroded steel structures according to claim 1, characterized in that: In step S4, the pulse laser power is 300W to 1000W, the pulse width is 100ns to 300ns, the frequency is 200kHz to 4000kHz, the scanning speed is 8000mm / s to 10000mm / s, and the line spacing is 0.08mm to 0.12mm.

9. The wet high-power combined laser cleaning method for severely corroded steel structures according to claim 8, characterized in that: In step S4, the pulse laser is a nanosecond pulse laser, and the number of times the area to be cleaned is cleaned by the nanosecond pulse laser is one, two or more times, and the impact of cleaning on the substrate is reduced by multiple nanosecond pulse laser cleanings, and the cleaning quality is improved by multiple nanosecond pulse laser cleanings; When the nanosecond pulse laser is used for cleaning more than twice, the power of the first nanosecond pulse laser is 500-1000W, the scanning speed is 8000-1000mm / s, the line spacing is 0.08-0.12mm, and the power of the nanosecond pulse laser after the first pass is 300-500W, and the scanning speed is 8000-10000mm / s.

10. The wet high-power combined laser cleaning method for severely corroded steel structures according to claim 1, characterized in that: In step S5, the area to be cleaned is rinsed with deionized water to remove possible remaining rust fragments, dirt and liquid residues in the cleaning process to ensure the cleaning effect.

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