A laser marking method for improving the corrosion resistance of the typing area of ​​high nitrogen stainless steel

Abstract

A laser marking method for improving the corrosion resistance of a high-nitrogen stainless steel typing area, the present invention relates to a laser marking method for improving the corrosion resistance of a high-nitrogen stainless steel typing area. The purpose of the present invention is to solve the problem of decreased corrosion resistance at the marking position after laser marking of high-nitrogen stainless steel bearings. The present invention adjusts the laser focus, laser power, and marking speed, and cooperates with high-pressure nitrogen purge cooling to obtain a clear and beautiful laser marking font, a martensitic relief feature in the typing area, and no microcracks, no pores, and no decreased corrosion resistance. The present invention is applied to the technical field of laser processing of metal material surfaces.

Description

Technical Field

[0001] The invention relates to a laser marking method for improving the corrosion resistance of a typing area of ​​high-nitrogen stainless steel. Background Art

[0002] In order to better distinguish various types of bearings, manufacturers need to mark the model information of each bearing on the surface of the bearing, and require that the model information is still clearly identifiable after the bearing is used. These model information also serve as anti-counterfeiting marks to prevent the emergence of counterfeit and inferior products. Laser marking technology has been widely used in the production of bearing model information. The principle of laser marking technology is to use a high-energy laser beam, focus it and act on the surface of the material, so that the surface material instantly melts or even vaporizes, and forms the required graphic mark by controlling the path of the laser on the surface of the material.

[0003] As the application environment of bearings gradually expands, the existing bearing materials and processing and manufacturing processes cannot meet the higher technical index requirements for the corrosion resistance of bearings. High nitrogen stainless steel is a high nitrogen martensitic stainless steel with better high temperature resistance, corrosion resistance and fatigue resistance than 9Cr18Mo stainless steel. This material partially replaces carbon with nitrogen, and forms a fine and dispersed carbonitride strengthening phase after heat treatment, which improves the hardness and wear resistance of the material. At the same time, the nitrogen and chromium elements dissolved in the martensite matrix play a role in improving the corrosion resistance of the material surface. However, after laser marking, the bearings made of this material have a phenomenon of decreased corrosion resistance at the marking position. The reason is that the current laser marking machine works in the atmospheric environment. The oxygen in the atmosphere combines with the Cr element in the high nitrogen stainless steel in the laser beam irradiation area to generate chromium oxide, resulting in uneven distribution of Cr elements in the martensite, the appearance of Cr-poor areas, and the inability to form a continuous passivation film, which affects the corrosion resistance of the marking position. Summary of the invention

[0004] The purpose of the invention is to solve the problem that the corrosion resistance of the marking position decreases after laser marking of high nitrogen stainless steel bearings, and to propose a laser marking method for improving the corrosion resistance of the marking area of ​​high nitrogen stainless steel.

[0005] The laser marking method for improving the corrosion resistance of the typing area of ​​high nitrogen stainless steel of the present invention is carried out as follows:

[0006] 1. Ultrasonic cleaning is performed on the surface of the high nitrogen stainless steel bearing ring, and drying is performed to obtain a cleaned high nitrogen stainless steel bearing ring;

[0007] 2. Place the high nitrogen stainless steel bearing ring on the workbench of the laser marking machine, and set a high-pressure nitrogen nozzle on the workbench of the laser marking machine; adjust the laser focus position so that the laser focus position is located in the area to be marked of the cleaned high nitrogen stainless steel bearing ring;

[0008] 3. Turn on the high-pressure nitrogen switch, and use the high-pressure nitrogen to purge and cool the area to be laser marked. Start laser marking after 1 to 3 seconds. After the laser marking is completed, turn off the high-pressure nitrogen switch after a delay of 10 to 15 seconds.

[0009] Beneficial effects of the present invention:

[0010] The invention provides a laser marking method for improving the corrosion resistance of a laser typing area of ​​high nitrogen stainless steel. By adjusting the laser focus, laser power and marking speed and coordinating high-pressure nitrogen purging and cooling, the laser typing area of ​​the high nitrogen stainless steel obtains a surface structure with a martensite relief feature. The laser typing effect is clear and beautiful. The corrosion resistance of the laser typing area of ​​the high nitrogen stainless steel is improved without reducing the hardness of the typing area. The corrosion resistance of the laser typing area is tested by a 196-hour accelerated corrosion experiment using acid salt spray. No pitting pits appear in the laser typing area, and the laser typing area has the same corrosion resistance as that of the high nitrogen stainless steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a schematic diagram of a laser marking method for improving the corrosion resistance of the laser marking area of ​​high nitrogen stainless steel;

[0012] Figure 2 This is a low-magnification scanning electron microscope photo of the font after the laser marking method of the present invention;

[0013] Figure 3 This is a high-magnification scanning electron microscope photo of the font after the laser marking method of the present invention;

[0014] Figure 4 This is a scanning electron microscope photo of the font after laser marking without high-pressure nitrogen purging. DETAILED DESCRIPTION

[0015] The technical solution of the present invention is not limited to the specific implementation modes listed below, but also includes any combination of the specific implementation modes.

[0016] Specific implementation method 1: In this implementation method, a laser marking method for improving the corrosion resistance of the typing area of ​​high nitrogen stainless steel is carried out as follows:

[0017] 1. Ultrasonic cleaning is performed on the surface of the high nitrogen stainless steel bearing ring, and drying is performed to obtain a cleaned high nitrogen stainless steel bearing ring;

[0018] 2. Place the high nitrogen stainless steel bearing ring on the workbench of the laser marking machine, and set a high-pressure nitrogen nozzle on the workbench of the laser marking machine; adjust the laser focus position so that the laser focus position is located in the area to be marked of the cleaned high nitrogen stainless steel bearing ring;

[0019] 3. Turn on the high-pressure nitrogen switch, and use the high-pressure nitrogen to purge and cool the area to be laser marked. Start laser marking after 1 to 3 seconds. After the laser marking is completed, turn off the high-pressure nitrogen switch after a delay of 10 to 15 seconds.

[0020] Specific implementation method 2: This implementation method is different from specific implementation method 1 in that: the method of ultrasonic cleaning in step 1 is: using an ultrasonic cleaning machine to decontaminate the high nitrogen stainless steel bearing ring in an ethanol solution for 10 minutes. The rest is the same as specific implementation method 1.

[0021] Specific implementation method 3: This implementation method is different from specific implementation method 1 or 2 in that the drying in step 1 is: drying in a vacuum drying oven at 40° C. for 1 hour. The rest is the same as specific implementation method 1 or 2.

[0022] Specific implementation method 4: This implementation method is different from specific implementation methods 1 to 3 in that: a shaft is set on the workbench of the laser marking machine, and the high-pressure nitrogen nozzle is fixed on the shaft, and the shaft drives the high-pressure nitrogen nozzle to rotate. Other aspects are the same as specific implementation methods 1 to 3.

[0023] Specific embodiment 5: This embodiment is different from specific embodiments 1 to 4 in that the angle between the nozzle axis and the shaft is 15 to 30 degrees. The rest is the same as specific embodiments 1 to 4.

[0024] Specific implementation example 6: This implementation example is different from specific implementation examples 1 to 5 in that the laser wavelength is 1064 nm and the laser power is set to 6 to 8 W. The rest is the same as specific implementation examples 1 to 5.

[0025] Specific implementation method 7: This implementation method is different from specific implementation methods 1 to 6 in that the laser marking speed is 300-400 mm / s. The rest is the same as specific implementation methods 1 to 6.

[0026] The following examples are used to verify the beneficial effects of the present invention:

[0027] Embodiment 1: A laser marking method for improving the corrosion resistance of a laser marking area of ​​high nitrogen stainless steel in this embodiment comprises the following steps:

[0028] 1. Ultrasonic cleaning of the surface of high nitrogen stainless steel bearing rings: Use an ultrasonic cleaner to decontaminate the high nitrogen stainless steel bearing rings in an ethanol solution for 10 minutes, then put them into a vacuum drying oven for drying at a set temperature of 40°C for 1 hour to completely dry the high nitrogen stainless steel bearing rings for standby use.

[0029] 2. A shaft is set on the workbench of the laser marking machine, and the high-pressure nitrogen nozzle is fixed on the shaft. The shaft drives the high-pressure nitrogen nozzle to rotate (such as Figure 1As shown, 1-bearing ring to be laser marked; 2-laser beam; 3-laser marking machine lens; 4-select shaft; 5-high-pressure nitrogen nozzle);

[0030] Then place the cleaned high-nitrogen stainless steel bearing ring on the workbench of the laser marking machine, adjust the position of the high-pressure nitrogen nozzle, and make the angle between the nozzle axis and the shaft rod 15 to 30 degrees. The shaft rod speed drives the high-pressure nitrogen nozzle to rotate, so that the high-pressure nitrogen purges and cools the area to be laser marked.

[0031] 3. Adjust the laser focus position so that the laser focus position is at the height of the bearing ring to be marked, set the laser power to 6-8 watts, the laser marking speed to 300-400 mm / s, and set the laser marking font size and the layout of the characters to be marked according to the size of the bearing ring. The laser wavelength is 1064nm.

[0032] 4. Turn on the high-pressure nitrogen switch and start laser marking after 2 seconds. After the laser marking is completed, turn off the high-pressure nitrogen switch after a delay of 10 seconds.

[0033] The laser-marked characters were observed using a scanning electron microscope. The laser-marked area showed martensite relief features and had no microcracks or pores. Figure 2 This is a low-magnification scanning electron microscope photograph of the laser-marked font obtained by using this embodiment. In the figure, the laser-marked font is clear and beautiful. Figure 3 This is a high-magnification scanning electron microscope photograph of the laser-marked font obtained in this example. The laser-marked area shows martensite relief characteristics without microcracks or pores.

[0034] Figure 4 This is a scanning electron microscope photo of the font after laser marking without high-pressure nitrogen purging. The picture shows that micro cracks and small black holes appear in the typing area. The corrosion resistance of the laser typing area was tested by an acid salt spray accelerated corrosion test for 196 hours. The test results show that no pitting corrosion pits appear in the laser typing area after high-pressure nitrogen purging, and the laser typing area has the same corrosion resistance as high-nitrogen stainless steel. However, after the acid salt spray accelerated corrosion test, pitting corrosion pits appear in the laser typing area after the font area is not purged with high-pressure nitrogen, and the corrosion resistance is reduced.

Claims

1. A laser marking method for improving the corrosion resistance of the typing area of ​​high nitrogen stainless steel, characterized in that The method proceeds as follows:

1. Ultrasonic cleaning is performed on the surface of the high nitrogen stainless steel bearing ring, and drying is performed to obtain a cleaned high nitrogen stainless steel bearing ring; 2. Place the high nitrogen stainless steel bearing ring on the workbench of the laser marking machine, and set a high-pressure nitrogen nozzle on the workbench of the laser marking machine; adjust the laser focus position so that the laser focus position is located in the area to be marked of the cleaned high nitrogen stainless steel bearing ring; 3. Turn on the high-pressure nitrogen switch, and use the high-pressure nitrogen to purge and cool the area to be laser marked. Start laser marking after 1 to 3 seconds. After the laser marking is completed, turn off the high-pressure nitrogen switch after a delay of 10 to 15 seconds. The laser wavelength is 1064nm, the laser power is set to 6 to 8W, and the laser marking speed is 300 to 400mm / s.

2. A laser marking method for improving the corrosion resistance of the typing area of ​​high nitrogen stainless steel according to claim 1, characterized in that The method of ultrasonic cleaning in step 1 is: using an ultrasonic cleaning machine to decontaminate the high nitrogen stainless steel bearing ring in an ethanol solution for 10 minutes.

3. A laser marking method for improving the corrosion resistance of the typing area of ​​high nitrogen stainless steel according to claim 1, characterized in that The drying in step 1 is: drying in a vacuum drying oven at 40°C for 1 hour.

4. A laser marking method for improving the corrosion resistance of a high nitrogen stainless steel typing area according to claim 1, characterized in that A shaft rod is arranged on the workbench of the laser marking machine, and a high-pressure nitrogen nozzle is fixed on the shaft rod, and the shaft rod drives the high-pressure nitrogen nozzle to rotate.

5. A laser marking method for improving the corrosion resistance of the typing area of ​​high nitrogen stainless steel according to claim 1, characterized in that The included angle between the nozzle axis and the shaft is 15 to 30 degrees.

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