The Structure of Iron Powder Aggregation Obtained by Selective Laser Melting

Abstract

A powder of different fractional composition was obtained from the iron ingot using the melt atomization method, from which samples for further studies were grown on the EOSint M270 unit using the selective laser melting (SLM) method. When considering the thin sections of the samples, we observed equiaxed recrystallized grains up to 20 μm in size, randomly distributed particles in the form of fragments up to 5 μm in size and equally oriented non-axial crystallites, forming groups in the form of arcuate layers with a front width of 800 μm and depth from 10 to 30 microns. Between them, narrow zones of increased chemical content were found, which are interpreted as probable traces of the stoppages of thermal fronts. We recorded traces of mass localized microplastic flow in the form of extended (up to 350x40 µm) and curved microregions with unequal-sized grains bordering microregions filled with equiaxial recrystallized grains due to the action of non-uniform thermal fields. Thus, in metal objects produced by the SLM, the complex morphology of the structure indicates a combination of different-scale mechanisms of structural changes. It has been established that in non-stationary temperature conditions of structure formation, the role of kinetic processes increases.