Selective Laser Melting of Iron Powder: Observation of Melting Mechanism and Densification Behavior Via Point-Track-Surface-Part Research

This paper presents the following procedure of additive manufacturing technology: point → track → surface → part, each part including different research aspects of selective laser melting (SLM) process. First, the transmissivity of laser through powder layer is measured with various powder layer thicknesses and particle sizes. The evolution of track cross section dimension is studied with different laser parameters and powders in track research. A surface quality including morphology and roughness research is shown in surface section. In this part, a single melted layer with smooth surface Ra 12.5 μm can be obtained with high laser density. After the part was established, the density and microstructure of SLM Fe part are present. The microstructural features of SLM Fe experienced an interesting change as follows: secondary sorbite → martensite → pearlite with decrease in laser energy density. At last, a simple SLM-process model was described.