Abstract
Optimization of processing parameters and exposure strategies is usually performed in additive manufacturing to set up the process; nevertheless, standards for roughness may not be evenly matched on a single complex part, since surface features depend on the building direction of the part. This paper aims to evaluate post processing treating via laser surface modification by means of scanning optics and beam wobbling to process metal parts resulting from selective laser melting of stainless steel in order to improve surface topography. The results are discussed in terms of roughness, geometry of the fusion zone in the cross-section, microstructural modification, and microhardness so as to assess the effects of laser post processing. The benefits of beam wobbling over linear scanning processing are shown, as heat effects in the base metal are proven to be lower.
Highlights
Additive manufacturing is receiving increasing interest in a wide range of industrial applications.In particular, new possibilities in lightweight design and direct fabrication of functional end-use parts are offered by selective laser sintering and melting of metal powders by means of laser irradiation [1,2]
(as for any additive layer manufacturing), since the Computer Aided Design (CAD) model of the object is preliminarily sliced into layers, the resulting contour of the real part is a stepped approximation of the nominal surface; it has been proved [5] that a staircase effect is induced (Figure 1) depending on both the local theoretical curvature and the sloping angle with the building direction
Surface modification by means of laser beam is effective as a possible post processing treatment over stainless steel components from additive manufacturing, inpost orderprocessing to improvetreatment the Surface modification by meansresulting of laser beam is effective as a possible surface topography
Summary
Additive manufacturing is receiving increasing interest in a wide range of industrial applications.In particular, new possibilities in lightweight design and direct fabrication of functional end-use parts are offered by selective laser sintering and melting of metal powders by means of laser irradiation [1,2]. (as for any additive layer manufacturing), since the Computer Aided Design (CAD) model of the object is preliminarily sliced into layers, the resulting contour of the real part is a stepped approximation of the nominal surface; it has been proved [5] that a staircase effect is induced (Figure 1) depending on both the local theoretical curvature and the sloping angle with the building direction. The thickness of the building layers can theoretically be reduced to improve surface finish, a threshold of minimum slicing is given by the average powder grain size. Depending on the manufacturer and the powder size, arithmetic as-built roughness usually ranges from 8 to 20 μm [6], whereas tighter standards could be required [7]
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