Fabrication of NiCr alloy parts by selective laser melting: Columnar microstructure and anisotropic mechanical behavior

NiCr alloy, because of its wide applications in electrical elements and dental field was widely studied in the past. In this work, NiCr cubes and tensile specimens were fabricated by using a new processing technique-selective laser melting (SLM). Microstructural and mechanical behavior characterization of SLM-processed NiCr components was performed. An unusual columnar microstructural architecture composed of 〈1 0 0〉 texture (corresponding to (2 0 0) plane) oriented the building direction was observed. Moreover, it was found that the columnar grain growth across the melt pools occurred during the SLM process and the growth trend became stronger with the decrease of the laser scanning speed. Associated with the microstructural characteristic, an anisotropic mechanical behavior at different reference planes (i.e., at the horizontal and vertical surfaces) was demonstrated for the samples fabricated using different processing parameters. The results showed that with increasing the laser scanning speed, the microhardness at the horizontal surface decreased, while at the vertical surface it increased; an increase of the yield strength (YS) and the ultimate tensile strength (UTS) was observed.