The fatigue strength of additively manufactured metal parts strongly depends on the quality of their surface, which is relatively rough in the as-built state. In this thesis, the effect of plasma electrolytic polishing on the fatigue strength of flat X2CrNiMo17-12-2 (AISI 316L) stainless steel specimens, produced by laser powder bed fusion (PBF-LB), was evaluated experimentally. Two groups of specimens were prepared, each with fifteen specimens: one in the as-built state and the other treated by plasma electrolytic polishing. The surface condition was characterised by profile and areal roughness parameters and by the parameters of the Abbott bearing-area curve, measured with a MarSurf PS 10 stylus instrument and a Keyence VHX-6000 digital microscope. The two groups were compared by tensile tests and by axial fatigue tests at a stress ratio of R = −1. Polishing reduced the arithmetic mean roughness of the profile from 6.93 µm to 0.43 µm, i.e. by approximately 94 %, while the tensile mechanical properties remained practically unchanged. At equal stress amplitudes, the polished specimens reached approximately twice the number of cycles to failure, except at the highest load levels. The results confirm that plasma electrolytic polishing considerably improves the fatigue resistance of additively manufactured stainless steel.
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