Li, S.-H., Zhao, Y., Kumar, P., & Ramamurty, U. (2022). Effect of initial dislocation density on the plastic deformation response of 316L stainless steel manufactured by directed energy deposition. Materials Science and Engineering: A, 851, 143591. https://doi.org/10.1016/j.msea.2022.143591
Abstract:
The relationship between the microstructural features (such as the solidification cells and initial dislocation densities) and the tensile properties alloys additively manufactured (AM) using techniques such as laser powder bed fusion (L-PBF) and directed energy deposition (DED) is yet to be firmly established. In this work, a detailed investigation into the structure-property relations in DED 316L austenitic stainless steel (316L SS) was conducted and contrasted with that of L-PBF one. The microstructural parameters were varied systematically by changing the laser energy employed. Results show that while the sizes of grains and cells and the volume fraction of the oxide particles increase with increasing laser energy, the dislocation density decreases. Unlike the L-PBF alloy where the dislocations decorate the cell walls (with the cell interiors being relatively free of them), dislocations are distributed homogeneously in DED 316L SS. The yield strength of the DED alloys are lower than the L-PBF alloy, but much higher than that of a well annealed alloy that is manufactured in the conventional way. A Hall-Petch type relation, wherein the cell size is taken as the plastic deformation controlling microstructural length scale, cannot capture the yield strength variation. Instead, the initial dislocation density was shown to dominate both the yield strength and the work hardening behavior.
License type:
Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)
Funding Info:
This research / project is supported by the Agency for Science, Technology and Research - Structural Metal Alloys Programme
Grant Reference no. : A18B1b0061
This work was supported by the Makino-NTU AM Collaboration Project