Process parameter optimisation for Waspaloy using Laser-Directed Energy Deposition with Powder

Sammanfattning: Material utilisation is of importance in the manufacturing industry formaking the most of each material, minimising waste and increasing cost-effectiveness. In this thesis, samples of Waspaloy built with the method of L-DED-P has been analysed in order to investigate how process pa-rameters influence the build quality and geometrical accuracy in as-builtobjects. The samples analysed was built in single rows of one, three,five and fifteen layers. A build process was used in which the sampleswere built with individual combinations of the process parameters laserpower, scanning speed, and powder flow. Each combination of processparameters was used to build one track for each layer height.Analysis included defect analysis with light optical microscopy, andpost-processing with ImageJ for automatic identification, quantification,and collection of measurements. A qualitative analysis was performed andthe sample properties and characteristics was described in terms of theamount of defects, including a descriptive assessment of defect severity.Etched samples revealed a columnar grain structure in samples, which was apparent in builds with at least three layers.The results presented show a difference in build height, quantity andsize of pores, and the presence or absence of other defects such as lack of fusion. Sample 3 which was built with high laser power, slow scan-ning speed, and high powder feed show promising results with one ofthe highest build rates of all samples, combined with a low normalisedpore distribution. The sample experiences partial hardening, with hard-ness values reaching 320 HV, but still promisingly show no sign of crackformation.It is concluded that powder feed relates primarily to the build rateof the samples, and the scanning speed together with the laser power influence the quality of the build, where high laser power and low scanningspeed tends to form well behaving samples with few defects, whilst other combinations increase the risk of defects.