Effect of Laser Irradiation Mode on L-PBF Ti6Al4V Thin Sections

The increased freedom to design in Laser Powder Bed FusionLaser powder bed fusion (L-PBF) (L-PBF) has catered to the need for lowering materialMaterials usage and weight of parts in various industries including the biomedicalBiomedical industry through the introduction of lattice-architectured metamaterials. Though their macro-mechanical propertiesMechanical properties are adequately studied, often issues pertaining to the quality of latticeLattices architecture are ignored. The quality of latticesLattices is directly dependent on the quality of strutsStruts as the building block of latticeLattices architecture. In addition to the processProcess parameters’ effects of L-PBFLaser powder bed fusion (L-PBF) on the quality of strutsStruts, the mode of laser irradiation may play a role in this trend. This work has studied the effect of laser irradiation mode on the quality of strutsStruts through analysis of surface topographySurface topography and roughness, defectsDefects nature and the ability to print strutsStruts of various diameters (0.1–1 mm) and angles of inclination (10˚-90˚). Continuous laser irradiation was capable of printing finer strutsStruts (d ≥ 0.2 mm) with better geometry (circularity) at lower angles of inclination, while the pulsed laser irradiation rendered better surface quality with less loose powder particles sinteringSintering on the surface. The geometry (circularity) of pulsed laser was better at higher angles of inclination. The defectsDefects appeared to be mainly keyholes, balling and gas porosityPorosity although some cracksCrack were detected for the pulsed laser printed strutsStruts and flow gaps for continuous mode. The microstructureMicrostructure of pulsed irradiation is slightly finer than continuous irradiation.