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To study the influence of different cleaning methods on the corrosion resistance of 316L stainless steel surface, this paper carried out polarisation curves and electrochemical impedance spectroscopy studied on the uncleaned, acid pickling cleaning, and picosecond laser cleaning samples. The surface morphology of the samples after electrochemical testing was detected by laser confocal microscopy and scanning electron microscopy, and then the electrochemical corrosion behaviour of the samples in 3.5% NaCl solution was analysed under different cleaning methods. The results show that compared with the uncleaned sample, the corrosion potential of the sample after picosecond laser cleaning was relatively improved. At this time, the corrosion current density was as low as 2.29 × 10–6 A/cm2, the polarisation resistance value was as high as 18615 Ω·cm2, the impedance modulus was as high as 5.5 × 105 Ω, and the capacitance-impedance radius reached the maximum value. In conclusion, the corrosion resistance of the sample after picosecond laser cleaning was better. [ABSTRACT FROM AUTHOR]

• This paper designs a depth-of-field 3D code which can be used for product traceability anti-counterfeiting. • Studying the effect of different laser parameters on the depth-of-field unit module. • Research on recognition and information reading of depth of field 3D code. In order to reduce the market in a large number of counterfeit imitation products, product traceability anti-counterfeiting by more and more attention. Therefore, it is imperative to study product traceability and anti-counterfeiting marking technology. However, for products within a limited size, the data capacity of traditional Data Matrix (DM) code is insufficient to meet the storage requirements, and it is easy to clone and copy, which limits the development of laser marking technology. In order to improve the replication difficulty and information storage capacity of the Data Matrix code, the depth-of-field (DOF) 3D code is devised by adding Z-axis depth information to the original Data Matrix code, which can accommodate a larger information storage capacity and improve the reproduction difficulty of DM code, thus meeting the current commercial demand. In this paper, cemented carbide is taken as the research object, and DOF 3D code is marked on its surface by femtosecond laser, and the optimal process parameters are determined. At the same time, the recognition and information reading of DOF 3D code is studied, and the correctness and reliability of its information acquisition are tested. [ABSTRACT FROM AUTHOR]

In order to explore the influence of picosecond laser on the cleaning quality of 316L stainless steel, and verify the feasibility of laser cleaning technology on stainless steel. In this paper, we used a picosecond laser for cleaning experiments on contaminated 316L stainless steel to study the effect of different laser process parameters on its surface cleaning quality and used a scanning electron microscope, energy dispersive X-ray spectrometer, digital microhardness tester and laser confocal microscope and other testing techniques to test the samples before and after cleaning. The results show that picosecond laser removal of stainless steel surface contaminants was the most effective when the laser power density was 19.1 × 105 W/cm2, the repetition rate was 80 kHz, the scanning speed was 1900 mm/s and the scanning spacing was 0.03 mm. Compared with the traditional cleaning process, the surface quality of the laser-cleaned samples was higher and more effective, which provided a reference from the application of laser cleaning technology on stainless steel surfaces. [ABSTRACT FROM AUTHOR]