Selective laser melting of iron-based powder

Selective laser melting (SLM) is driven by the need to process near full density objects with mechanical properties comparable to those of bulk materials. During the process the powder particles are completely molten by the laser beam. The resulting high density allows avoiding lengthy post-processing as required with selective laser sintering (SLS) of metal powders. Unlike SLS, SLM is more difficult to control. Because of the large energy input of the laser beam and the complete melting of particles problems like balling, residual stresses and deformation occur. This paper will describe SLM applied to a mixture of different types of particles (Fe, Ni, Cu and Fe3P) specially developed for SLM. The different appearing phenomenons are discussed and the process optimization is described. The latter includes an appropriate process parameter adjustment and the application of special scanning strategies. Resulting parts are characterized by their microstructure, density and mechanical properties.