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A Review on Layer Formation Studies in Selective Laser Melting of Steel Powders and Thin Wall Parts Using Pulse Shaping

Aarti Gupta

Abstract


This paper advances the conclusions of the selective laser melting (SLM) of tool steel and stainless steel powders. The characteristic feature is the melting of single layers in deep powder beds by a continuous CO2 laser. First, effect of development parameters on the surface roughness for each material is examined. Based on these results combined with visual observation of the solidified tracks, the question is then discussed as how the process ability of various type of steels is changed. Accordingly, Pulse shaping is a technique used to temporally distribute energy within a single laser pulse. This delivers to user an added degree of control over the heat delivered to the laser material communication zone. Pulses which makes a gradual heating or a stretched cooling effect can be produced with peak power/pulse energy combinations specifically tailored to control melt pool properties and eventual part formation. The results show that surface morphology of layers is affected strongly by scan spacing, thereby giving a lower normal roughness at compact scan spacing. The effect of scan speed is also amazing. This examination used a pulsed 550WNd: YAG laser to generate thin wall Inconel 625® parts using pulse shapes that delivered a variety of different energy distributions. Parts built with and without pulse figure control were measured for width, top and side surface roughness. The efficiency of pulse shaping regulator is discussed including potential benefits for use within the Selective Laser Melting process. Pulse shaping was shown to reduce spatter ejection during processing, advances the top surface roughness of parts and diminishes melt pool width.

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References


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