2023 年 64 巻 6 号 p. 1135-1142
We first fabricated the single crystal of 316L stainless steel by laser powder bed fusion (L-PBF), focusing on the applicability of the µ-Helix scanning strategy with narrow pitch as a method for obtaining a single crystal. Various combinations of laser power and laser scanning speed were examined. The cubic block samples were orientated to 〈100〉 in the X-laser scanning direction, to 〈110〉 in the Y-laser scanning direction, and to 〈110〉 in the building direction, which is contrary to that obtained by the µ-Helix scanning strategy in electron beam melting (EBM), in which the X- and Y-laser scanning directions are orientated to 〈110〉, and Z-direction is oriented to 〈100〉 direction. Also, it has been demonstrated that melt pool monitoring by on-axis and off-axis dual photodiodes can detect the nonequivalence of ±X-scanning and ±Y-scanning, which is responsible for the unexpected crystal orientation.
