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The surfaces of implantable medical devices should present proper corrosion and mechanical resistance properties to fulfil their functions. Marking techniques are used for identification and traceability purposes but often generate surface modifications. Because surface defects affect corrosion resistance, the effects of marking processes must be investigated. This paper presents the effects of pulsed Nd:YAG laser marking techniques on the corrosion resistance of ASTM F139 austenitic stainless steel compared to that of mechanical marking techniques. The corrosion resistance was evaluated by electrochemical methods, and the surface was analysed by scanning electron microscopy with a field emission gun (SEM-FEG) coupled to an energy dispersive X-ray spectrometer. The surface characterisation showed the occurrence of microstructure variation due to the high temperatures involved in the laser melting process. Compared to the mechanical method, the laser marking technique had a deleterious effect on the resistance of ASTM F139 stainless steel to localised corrosion, increasing its susceptibility to pitting corrosion. These results were related to changes in the passive film properties, surface morphology and chemical composition. |
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