Method for improving pitting corrosion resistance of stainless steel by coupling heat and humidity assisted laser treatment

Abstract

This invention relates to a method for improving the pitting corrosion resistance of stainless steel through heat and humidity coupled assisted laser treatment. The method includes preheating a target stainless steel workpiece to a preset temperature range using a heating device and holding it at that temperature; humidifying the target stainless steel workpiece to a preset humidity range using an auxiliary humidification device while holding it at that temperature; and treating the stainless steel surface with a pulsed laser beam under the preset temperature and humidity conditions, thereby forming a continuous and dense protective oxide film on the surface of the target stainless steel workpiece. This invention employs heat and humidity coupled assisted laser treatment to form a continuous and dense protective oxide film on the surface of the target stainless steel workpiece. Heating ensures the controllability of the stainless steel substrate temperature and the stability of the passivation film. The high humidity environment provides an active oxygen environment for laser treatment, compensating for the adverse effects of reduced surface moisture caused by heating, while avoiding potential environmental hazards and surface damage. This method is green, efficient, and environmentally friendly.

Description

Technical Field

[0001] This invention relates to the field of corrosion-resistant processing technology for metal material surfaces, and in particular to a method for improving the pitting corrosion resistance of stainless steel through heat and humidity coupled assisted laser treatment. Background Technology

[0002] Stainless steel, with its excellent mechanical properties and corrosion resistance, is widely used in industrial and construction fields with harsh service environments. The excellent corrosion resistance of stainless steel is due to the protective passivation film formed on its surface. However, when this passivation film is damaged by corrosive environments such as chloride ions, stainless steel experiences pitting corrosion and other localized corrosion. Therefore, pitting corrosion resistance, measured by indicators such as pitting potential, is crucial for evaluating the corrosion resistance and passivation capability of stainless steel components. Currently, pickling passivation solutions and passivation pastes are commonly used in engineering to improve the pitting corrosion resistance of stainless steel. Chemical passivation often uses corrosive strong acids such as nitric acid and citric acid, as well as strong oxidizing media such as hydrogen peroxide; therefore, post-processing after chemical passivation is difficult and does not meet the trend of green and environmentally friendly development. Furthermore, although electrochemical passivation is also used in some industries, it tends to cause over-passivation when treating components with a certain sensitization tendency.

[0003] Lasers can create plasma impacts, provide instantaneous high-temperature heating, and oxidize metal surfaces, contributing to the formation of a protective passivation film. However, currently available laser surface modification technologies for improving the corrosion resistance of stainless steel mainly focus on methods such as preparing superhydrophobic surface morphologies and using laser assistance to increase the nitrogen content of weld metal during welding. Furthermore, patent [CN202210315841.6] discloses a laser processing method for creating corrosion-resistant black engravings on stainless steel, using picosecond laser marking to prepare a black surface and passing a 9-hour salt spray test. However, the 9-hour salt spray test often fails to meet the corrosion resistance requirements for marine environments. How to modify the pitting corrosion resistance of stainless steel surfaces on a large scale in an environmentally friendly and efficient manner remains a challenge.

[0004] From the perspective of the formation principle of stainless steel passivation films, the main way to improve the corrosion resistance of stainless steel passivation films through laser treatment is to form a continuous chromium-rich oxide film on the surface under laser irradiation. However, due to the rapid action of the laser spot on the metal surface, the focused energy of the spot, and the high thermal conductivity of the metal, temperature fluctuations of the stainless steel substrate and changes in ambient temperature and humidity have a significant impact on the formation of the chromium-rich passivation film on the metal surface under laser irradiation. This can often lead to problems such as unstable passivation quality and reduced corrosion resistance. Therefore, determining the appropriate method to ensure that stainless steel obtains a passivation film with stable quality and excellent pitting corrosion resistance is currently crucial for improving the corrosion resistance of stainless steel through laser treatment. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for improving the pitting corrosion resistance of stainless steel by heat and humidity coupled assisted laser treatment, which is in response to the shortcomings of the prior art.

[0006] The technical solution of this invention to solve the above-mentioned technical problems is as follows: A method for improving the pitting corrosion resistance of stainless steel through heat and humidity coupled assisted laser treatment, comprising the following steps:

[0007] The target stainless steel workpiece after cleaning is preheated to a preset temperature range using a heating device and then kept at that temperature.

[0008] The target stainless steel workpiece is humidified using an auxiliary humidification device while in a heat preservation state, and the relative humidity of the surface environment of the target stainless steel workpiece is controlled within a preset humidity range.

[0009] Under the environmental conditions of the preset temperature range and preset humidity range, a pulsed laser beam is used to treat the stainless steel surface and form a continuous and dense protective oxide film on the surface of the target stainless steel workpiece.

[0010] The beneficial effects of this invention are as follows: The method for improving the pitting resistance of stainless steel by heat and humidity coupled-assisted laser treatment uses heating and heat preservation coupled with high humidity to form a continuous and dense protective oxide film on the surface of the target stainless steel workpiece. The heating method ensures the controllability of the stainless steel substrate temperature and prevents the instability of the passivation film quality caused by uneven heat conduction. The high humidity environment provides an active oxygen environment for the laser treatment to improve the passivation ability of stainless steel, which makes up for the adverse effect of the reduction of surface water vapor caused by heating. At the same time, it avoids the potential environmental hazards and shortcomings of conventional chemical / electrochemical passivation in terms of post-treatment and potential surface damage. It has the technical characteristics of being green, efficient and environmentally friendly, and having stable and controllable surface passivation quality.

[0011] Based on the above technical solution, the present invention can be further improved as follows:

[0012] Further: Before preheating the target stainless steel workpiece after cleaning, a partition plate is placed between the heating device and the target stainless steel workpiece.

[0013] The beneficial effects of the above-mentioned further solution are: by placing an isolation plate between the heating device and the target stainless steel workpiece, the target stainless steel workpiece can be protected, preventing it from being contaminated, and at the same time, it is beneficial to heat the target stainless steel workpiece more evenly.

[0014] Furthermore, the isolation plate is made of stainless steel, and the thickness of the isolation plate is no more than 1mm.

[0015] The beneficial effects of the above-mentioned further solutions are: using stainless steel material, on the one hand, maintains the same material as the target stainless steel workpiece, which is conducive to controlling the preheating temperature; on the other hand, stainless steel material has good thermal conductivity and high heating efficiency.

[0016] Furthermore: the preset temperature range is 45-95℃, and the preset humidity range is above 65%.

[0017] Further: The specific method for the auxiliary humidification device to humidify the target stainless steel workpiece includes: the auxiliary humidification device generates water vapor and sprays it onto the surface of the target stainless steel workpiece, wherein the humidifying liquid used by the heating device to generate water vapor is ultrapure water, or a solution containing hydrogen peroxide and citric acid.

[0018] The beneficial effects of the above-mentioned further solution are as follows: by generating water vapor through the auxiliary humidification device, the ambient humidity of the target stainless steel workpiece surface can be changed. By using ultrapure water or a solution containing hydrogen peroxide and citric acid, the large amount of plasma generated by the laser acting on the metal surface can decompose a large number of water molecules on the metal surface into active oxygen in a high humidity environment, thereby forming a high-quality protective chromium-rich passivation film on the metal surface of the target stainless steel workpiece, which greatly improves the corrosion resistance of stainless steel.

[0019] Further: The auxiliary humidification device includes a humidity holding box with a light-transmitting plate on its top wall, a humidity sensor, a humidification device, and an exhaust fan. The humidity holding box is placed on the surface of the target stainless steel workpiece. The bottom wall of the humidity holding box has an opening for laser transmission. The humidification device is located on one side of the humidity holding box and is connected to the humidity holding box. The humidity sensor is located inside the humidity holding box and is electrically connected to the humidification device. The pulsed laser beam enters the humidity holding box and irradiates the surface of the target stainless steel workpiece through the opening. The exhaust fan is located on the other side wall of the humidity holding box and is connected to the humidity holding box. The heating device is located on the inner bottom wall of the humidity holding box and is located on one side of the opening.

[0020] The beneficial effects of the above-mentioned further solution are: the humidity sensor can detect the ambient humidity inside the humidity holding box and on the surface of the target stainless steel workpiece in real time, and the humidification device can provide feedback control to keep the ambient humidity inside the humidity holding box and on the surface of the target stainless steel workpiece constant within a preset humidity range; the exhaust fan can automatically control the discharge of humidifying gas.

[0021] Furthermore, the auxiliary humidification device also includes a positioning rod, one end of which is connected to the humidity holding box, and the other end of which is provided with a laser head for emitting the pulsed laser beam, and the laser head is located directly above the opening.

[0022] The beneficial effect of the above-mentioned further solution is that by setting the positioning rod, the laser head used to emit the pulsed laser beam can be fixed and supported, so that the pulsed laser beam emitted by the laser head can accurately and smoothly irradiate the surface of the target stainless steel workpiece.

[0023] Furthermore, the auxiliary humidification device also includes a dehumidifier, which is connected to the exhaust fan.

[0024] The beneficial effects of the above-mentioned further solution are: by setting the dehumidifier, the automatic recovery of the humidifying gas can be realized, which has the advantages of being green and efficient, and having controllable residual gas emission recovery.

[0025] Further: The laser power of the pulsed laser beam is 90W-170W, the overlap rate is 20-75%, and the pulse width is greater than or equal to 60ns.

[0026] A stainless steel product obtained by using the aforementioned heat and humidity coupled assisted laser treatment method to improve the pitting corrosion resistance of stainless steel. Attached Figure Description

[0027] Figure 1 This is a schematic flowchart of a method for improving the pitting corrosion resistance of stainless steel through heat and humidity coupled assisted laser treatment according to an embodiment of the present invention.

[0028] Figure 2 This is a schematic diagram of the structure of an auxiliary humidification device according to an embodiment of the present invention;

[0029] Figure 3 These are the potentiodynamic polarization curves of stainless steel workpieces without laser treatment and stainless steel workpieces treated with the heat and humidity coupled assisted laser of the present invention in 3.5% NaCl solution in several embodiments of the present invention. Detailed Implementation

[0030] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0031] like Figure 1 As shown, a method for improving the pitting corrosion resistance of stainless steel through heat and humidity coupled assisted laser treatment includes the following steps:

[0032] S1: Use heating device 12 to preheat the cleaned target stainless steel workpiece 13 to a preset temperature range and keep it at that temperature.

[0033] S2: Under the condition of heat preservation, the target stainless steel workpiece 13 is humidified using an auxiliary humidification device, and the relative humidity of the surface environment of the target stainless steel workpiece 13 is controlled within a preset humidity range.

[0034] S3: Under the environmental conditions of the preset temperature range and preset humidity range, a pulsed laser beam 3 is used to treat the stainless steel surface and form a continuous and dense protective oxide film on the surface of the target stainless steel workpiece 13.

[0035] In one or more embodiments of the present invention, before preheating the cleaned target stainless steel workpiece, a partition plate is placed between the heating device 12 and the target stainless steel workpiece. By placing the partition plate between the heating device 12 and the target stainless steel workpiece, the target stainless steel workpiece can be protected, preventing contamination, and at the same time, it facilitates more uniform heating of the target stainless steel workpiece.

[0036] Optionally, in one or more embodiments of the present invention, the isolation plate is made of stainless steel, and the thickness of the isolation plate is no more than 1 mm. Using stainless steel has two advantages: firstly, it maintains the same material as the target stainless steel workpiece 13, which is beneficial for controlling the preheating temperature; secondly, stainless steel has good thermal conductivity and high heating efficiency.

[0037] Optionally, in one or more embodiments of the present invention, the preset temperature range is 45-95°C.

[0038] Optionally, in one or more embodiments of the present invention, the preset humidity range is 65% or higher.

[0039] In one or more embodiments of the present invention, the specific method for humidifying the target stainless steel workpiece 13 using the auxiliary humidification device includes: the auxiliary humidification device generating water vapor and spraying it onto the surface of the target stainless steel workpiece 13; the humidifying liquid used by the heating device 12 to generate water vapor is ultrapure water, or a solution containing hydrogen peroxide and citric acid. By generating water vapor through the auxiliary humidification device, the ambient humidity of the target stainless steel workpiece 13 surface can be altered. By using ultrapure water, or a solution containing hydrogen peroxide and citric acid, the large amount of plasma generated by the laser acting on the metal surface can decompose a large number of water molecules on the metal surface into active oxygen under high humidity conditions, thereby forming a high-quality protective chromium-rich passivation film on the metal surface of the target stainless steel workpiece 13, greatly improving the corrosion resistance of the stainless steel.

[0040] like Figure 2As shown, in one or more embodiments of the present invention, the auxiliary humidification device includes a humidity holding box 4 with a light-transmitting plate on its top wall, a humidity sensor 5, a humidification device 8, and an exhaust fan 9. The humidity holding box 4 is placed on the surface of the target stainless steel workpiece 13. The bottom wall of the humidity holding box 4 is provided with an opening 6 for laser transmission. The humidification device 8 is disposed on one side of the humidity holding box 4 and is connected to the humidity holding box 4. The humidity sensor 5 is disposed inside the humidity holding box 4 and is electrically connected to the humidification device 8. The pulsed laser beam 3 enters the humidity holding box 4 and irradiates the surface of the target stainless steel workpiece 13 through the opening 6. The exhaust fan 9 is disposed on the other side wall of the humidity holding box 4 and is connected to the humidity holding box 4. The heating device 12 is disposed on the inner bottom wall of the humidity holding box 4 and is located on one side of the opening 6. The humidity sensor 5 can detect the ambient humidity inside the humidity holding box 4 and on the surface of the target stainless steel workpiece 12 in real time, and the humidification device 8 provides feedback control to keep the ambient humidity inside the humidity holding box 4 and on the surface of the target stainless steel workpiece 12 constant within a preset humidity range. The exhaust fan 9 can automatically control the discharge of humidified gas.

[0041] Optionally, in one or more embodiments of the present invention, the auxiliary humidification device further includes a positioning rod 2, one end of which is connected to the humidity holding box 4, and the other end of which is provided with a laser head 1 for emitting the pulsed laser beam 3, and the laser head 1 is located directly above the opening 6. By setting the positioning rod 2, the laser head 1 for emitting the pulsed laser beam 2 can be fixed and supported, so that the pulsed laser beam 3 emitted by the laser head 1 can accurately and smoothly irradiate the surface of the target stainless steel workpiece 12.

[0042] Optionally, in one or more embodiments of the present invention, the auxiliary humidification device further includes a dehumidifier 11, which is connected to the exhaust fan 9. By setting the dehumidifier 11, the automatic recovery of the humidifying gas can be achieved, which has the advantages of being green and efficient, and having controllable residual gas emission recovery.

[0043] In one or more embodiments of the present invention, the laser power of the pulsed laser beam 3 is 90w-170w, the overlap rate is 20-75%, and the pulse width is greater than or equal to 60ns.

[0044] The specific solutions are detailed in the following comparative examples and embodiments.

[0045] Comparative Example

[0046] The target stainless steel workpiece 13, after pre-cleaning, was directly used in a 3.5% NaCl solution for electrochemical potentiodynamic polarization testing. Typical results were obtained. Figure 3 As shown in curve OR, the pitting potential is around 0.25V.

[0047] Example 1

[0048] A method for improving the pitting corrosion resistance of stainless steel using heat and humidity coupled assisted laser treatment includes the following steps:

[0049] S1, the target stainless steel workpiece 13 after cleaning is preheated to a preset temperature range using the heating device 12, and the preheating temperature is greater than 45°C.

[0050] S2, the target stainless steel workpiece 13 is humidified using an auxiliary humidification device to control the humidity of the surface environment of the target stainless steel workpiece 13 at 65%, while maintaining the heat preservation state of the stainless steel workpiece.

[0051] S3, under heat preservation and moisture preservation conditions, a nanosecond pulsed laser beam 3 is used to treat the stainless steel surface. The laser power of the pulsed laser beam 3 is 90W, the overlap rate is 20%, and the pulse width is 60ns.

[0052] Potentiodynamic polarization tests after the above treatment showed that the pitting potential was 0.48V. Figure 3 Example 1 shows the curve.

[0053] Example 2

[0054] A method for improving the pitting corrosion resistance of stainless steel using heat and humidity coupled assisted laser treatment includes the following steps:

[0055] S1, the target stainless steel workpiece 13 after cleaning is preheated to a preset temperature range using the heating device 12, and the preheating temperature is 45°C.

[0056] S2, the surface humidity of the target stainless steel workpiece 13 is controlled at 95% by an auxiliary humidification device, while maintaining the heat preservation state of the stainless steel workpiece.

[0057] S3, under heat preservation and moisture preservation conditions, a nanosecond pulsed laser beam 3 is used to treat the stainless steel surface. The laser power of the pulsed laser beam 3 is 170w, the overlap rate is 70%, and the pulse width is 240ns.

[0058] Potentiodynamic polarization testing of the target stainless steel workpiece 13 after the above treatment showed that the pitting potential was 0.78V. Figure 3 Example 2 shows the curve.

[0059] Example 3

[0060] A method for improving the pitting corrosion resistance of stainless steel using heat and humidity coupled assisted laser treatment includes the following steps:

[0061] S1, the target stainless steel workpiece 13 after cleaning is preheated to a preset temperature range using the heating device 12, and the preheating temperature is 65°C.

[0062] S2, the surface humidity of the target stainless steel workpiece 13 is controlled at 65% by an auxiliary humidification device, while maintaining the heat preservation state of the stainless steel workpiece.

[0063] S3, under heat preservation and moisture preservation conditions, a nanosecond pulsed laser beam 3 is used to treat the stainless steel surface. The laser power of the pulsed laser beam 3 is 110w, the overlap rate is 50%, and the pulse width is 120ns.

[0064] Potentiodynamic polarization testing of the target stainless steel workpiece 13 after the above treatment showed that the pitting potential was 0.57V. Figure 3 Example 3 shows the curve.

[0065] Example 4

[0066] A method for improving the pitting corrosion resistance of stainless steel using heat and humidity coupled assisted laser treatment includes the following steps:

[0067] S1, the target stainless steel workpiece 13 after cleaning is preheated to a preset temperature range using the heating device 12, and the preheating temperature is 65°C.

[0068] S2, the surface humidity of the target stainless steel workpiece 13 is controlled at 95% by an auxiliary humidification device, while maintaining the heat preservation state of the stainless steel workpiece.

[0069] S3, under heat preservation and moisture preservation conditions, a nanosecond pulsed laser beam 3 is used to treat the stainless steel surface. The laser power of the pulsed laser beam 3 is 110w, the overlap rate is 75%, and the pulse width is 240ns.

[0070] Potentiodynamic polarization testing of the target stainless steel workpiece 13 after the above treatment showed that the pitting potential was 1.15V. Figure 3 Example 4 shows the curve.

[0071] Example 5

[0072] A method for improving the pitting corrosion resistance of stainless steel using heat and humidity coupled assisted laser treatment includes the following steps:

[0073] S1, the target stainless steel workpiece 13 after cleaning is preheated to a preset temperature range using the heating device 12, and the preheating temperature is 95°C.

[0074] S2, the surface humidity of the target stainless steel workpiece 13 is controlled at 65% by an auxiliary humidification device, while maintaining the heat preservation state of the stainless steel workpiece.

[0075] S3, under heat preservation and moisture preservation conditions, a nanosecond pulsed laser beam 3 is used to treat the stainless steel surface. The laser power of the pulsed laser beam 3 is 90W, the overlap rate is 70%, and the pulse width is 240ns.

[0076] Potentiodynamic polarization testing of the target stainless steel workpiece 13 after the above treatment showed that the pitting potential was 0.54V. Figure 3 Example 5 shows the curve.

[0077] Example 6

[0078] A method for improving the pitting corrosion resistance of stainless steel using heat and humidity coupled assisted laser treatment includes the following steps:

[0079] S1, the target stainless steel workpiece 13 after cleaning is preheated to a preset temperature range using the heating device 12, and the preheating temperature is 95°C.

[0080] S2, the surface humidity of the target stainless steel workpiece 13 is controlled at 95% by an auxiliary humidification device, while maintaining the heat preservation state of the stainless steel workpiece.

[0081] S3, under heat preservation and moisture preservation conditions, a nanosecond pulsed laser beam 3 is used to treat the stainless steel surface. The laser power of the pulsed laser beam 3 is 170w, the overlap rate is 20%, and the pulse width is 120ns.

[0082] Potentiodynamic polarization testing of the target stainless steel workpiece 13 after the above treatment showed that the pitting potential was 0.81V. Figure 3 Example 6 shows the curve.

[0083] It is evident that the method of improving the pitting corrosion resistance of stainless steel using heat and humidity coupled assisted laser treatment according to the present invention can significantly increase the pitting potential of stainless steel, thereby achieving a significant improvement in the corrosion resistance of stainless steel. When the laser power of the pulsed laser beam 3 is 110W, the overlap rate is 75%, and the pulse width is 240ns, an ultra-corrosion-resistant stainless steel surface with a pitting potential as high as 1.15V can be obtained. Figure 3 Example 4 shows the curve.

[0084] The present invention relates to a method for improving the pitting corrosion resistance of stainless steel through heat and humidity coupled assisted laser treatment. This method employs heating and heat preservation coupled with high humidity to form a continuous and dense protective oxide film on the surface of the target stainless steel workpiece 13. The heating method ensures the controllability of the stainless steel substrate temperature and prevents instability in the passivation film quality due to uneven heat conduction. The high humidity environment provides an active oxygen environment for the laser treatment to improve the passivation ability of stainless steel, compensating for the adverse effects of reduced surface moisture caused by heating. Simultaneously, it avoids the potential environmental hazards and shortcomings of conventional chemical / electrochemical passivation, such as post-treatment and potential surface damage. This method features green, efficient, environmentally friendly technology and stable and controllable surface passivation quality.

[0085] The present invention also provides a stainless steel product obtained by using the aforementioned heat and humidity coupled assisted laser treatment method to improve the pitting corrosion resistance of stainless steel.

[0086] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for improving the pitting corrosion resistance of stainless steel through heat and humidity coupled assisted laser treatment, characterized in that, Includes the following steps: The target stainless steel workpiece (13) after cleaning is preheated to a preset temperature range and kept warm using a heating device (12); In the heat preservation state, the target stainless steel workpiece (13) is humidified using an auxiliary humidification device, and the relative humidity of the surface environment of the target stainless steel workpiece (13) is controlled within a preset humidity range. Under the environmental conditions of the preset temperature range and preset humidity range, a pulsed laser beam (3) is used to treat the stainless steel surface and form a continuous and dense protective oxide film on the surface of the target stainless steel workpiece (13). Before preheating the cleaned target stainless steel workpiece (13), a partition plate is placed between the heating device (12) and the target stainless steel workpiece (13); The auxiliary humidification device includes a humidity holding box (4) with a light-transmitting plate on the top wall, a humidity sensor (5), a humidification device (8), and an exhaust fan (9). The humidity holding box (4) is placed on the surface of the target stainless steel workpiece (13). The bottom wall of the humidity holding box (4) is provided with an opening (6) for laser transmission. The humidification device (8) is located on one side of the humidity holding box (4) and is connected to the humidity holding box (4). The humidity sensor (5) is located on the humidity holding box. Inside the holding box (4), the humidity sensor (5) is electrically connected to the humidification device (8). The pulsed laser beam (3) enters the humidity holding box (4) and irradiates the surface of the target stainless steel workpiece (13) through the opening (6). The exhaust fan (9) is set on the other side wall of the humidity holding box (4) and is connected to the humidity holding box (4). The heating device (12) is set on the inner bottom wall of the humidity holding box (4) and is located on one side of the opening (6). The preset temperature range is 45-95℃, and the preset humidity range is above 65%.

2. The method for improving the pitting corrosion resistance of stainless steel by heat and humidity coupled assisted laser treatment according to claim 1, characterized in that, The isolation plate is made of stainless steel and its thickness is no more than 1 mm.

3. The method for improving the pitting corrosion resistance of stainless steel by heat and humidity coupled assisted laser treatment according to claim 1, characterized in that, The specific method for the auxiliary humidification device to humidify the target stainless steel workpiece (13) includes: the auxiliary humidification device generates water vapor and sprays it on the surface of the target stainless steel workpiece (13), wherein the humidification liquid for generating water vapor is ultrapure water or a solution containing hydrogen peroxide and / or citric acid.

4. The method for improving the pitting corrosion resistance of stainless steel by heat and humidity coupled assisted laser treatment according to claim 1, characterized in that, The auxiliary humidification device also includes a positioning rod (2), one end of which is connected to the humidity holding box (4), and the other end of which is provided with a laser head (1) for emitting the pulsed laser beam (3), and the laser head (1) is located directly above the opening (6).

5. The method for improving the pitting corrosion resistance of stainless steel by heat and humidity coupled assisted laser treatment according to claim 1, characterized in that, The auxiliary humidification device also includes a dehumidifier (11), which is connected to the exhaust fan (9).

6. The method for improving the pitting corrosion resistance of stainless steel by heat and humidity coupled assisted laser treatment according to any one of claims 1-5, characterized in that, The laser power of the pulsed laser beam (3) is 90w-170w, the overlap rate is 20-75%, and the pulse width is greater than or equal to 60ns.

7. A stainless steel product manufactured by the method of improving the pitting corrosion resistance of stainless steel using heat and humidity coupled assisted laser treatment as described in any one of claims 1-6.

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