Résumé

In order to drastically reduce the cycle and cost production of engine parts in the transport industry, we have developed laser powder melting processes to produce several key engine parts in maraging steel, Co-Cr and Inconel 718. Results presented here concerns maraging steel only. Laser melted samples were polished with three different treatments: Abrasive Flow Machining (from Extrudehone), Vibratory finishing (from Rosler) and MMP (Micro Machining Process from BESTinCLASS). The dimensional tolerance after polishing was 5µm. The resulting surface topographies were measured with Stylus Profilometry and Atomic Force Microscopy. The MMP process allows reducing the rms roughness (Rq) to 12 nm only for a 20µm x 20µm field of view. In order to investigate the surface treatments in terms of what characteristic length (i.e spatial frequency) have been filtered, we present the results with the help of power spectral density. Concerning the mechanical properties, the anisotropy of fatigue and tensile strength is not significant as a consequence of the direct melting process compared to sintering.

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