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Effect of hatch spacing and laser power on microstructure, texture, and thermomechanical properties of laser powder bed fusion (L-PBF) additively manufactured NiTi
This study systematically evaluates the effects of laser powder bed fusion additive manufacturing (L-PBF-AM) parameters (hatch spacing and laser power) on the thermomechanical behavior and microstructure of Ni50.8Ti49.2 shape memory alloy. The samples were fabricated with hatch spacings from 40 to 240 µm and laser powers of 50 and 100 W at a constant scanning speed of 125 mm/s, resulting in parts with volumetric energy density levels from 55 to 666 J/mm3 and two sets of linear energy densities of 0.4 and 0.8 J/mm. The results showed a reduced melt pool size and discontinuity of scan tracks with decreased laser power. Additionally, the porosity level was increased with larger hatch spacing and lower laser power. More notably, the transformation temperatures increased, and the critical stress, recoverable strain, and functional stability of samples improved with lower hatch spacing, where the recovery ratio of up to 90% was observed, regardless of the employed laser power. This study also discussed the relationship between the fabrication process and texture formation in the L-PBF-AM process. In conclusion, the advantage of L-PBF-AM was revealed in tailoring the microstructure from highly textured samples in [1 1 1] or [0 0 1] direction when hatch spacing lower than laser beam focused was employed, to the appearance of equiaxed solidification front with island grains and random orientations.
Saghaian, Sayed Ehsan, et al. "Effect of hatch spacing and laser power on microstructure, texture, and thermomechanical properties of laser powder bed fusion (L-PBF) additively manufactured NiTi." Optics and Laser Technology, vol. 149, no. C, Nov. 2021. https://doi.org/10.1016/j.optlastec.2021.107680
Saghaian, Sayed Ehsan, Nematollahi, Mohammadreza, Toker, Guher, Hinojos, Alejandro, Moghaddam, Narges Shayesteh, Saedi, Soheil, Lu, Charles Y., Mahtabi, Mohammad Javad, Mills, Michael J., Elahinia, Mohammad, & Karaca, Haluk E. (2021). Effect of hatch spacing and laser power on microstructure, texture, and thermomechanical properties of laser powder bed fusion (L-PBF) additively manufactured NiTi. Optics and Laser Technology, 149(C). https://doi.org/10.1016/j.optlastec.2021.107680
Saghaian, Sayed Ehsan, Nematollahi, Mohammadreza, Toker, Guher, et al., "Effect of hatch spacing and laser power on microstructure, texture, and thermomechanical properties of laser powder bed fusion (L-PBF) additively manufactured NiTi," Optics and Laser Technology 149, no. C (2021), https://doi.org/10.1016/j.optlastec.2021.107680
@article{osti_1977524,
author = {Saghaian, Sayed Ehsan and Nematollahi, Mohammadreza and Toker, Guher and Hinojos, Alejandro and Moghaddam, Narges Shayesteh and Saedi, Soheil and Lu, Charles Y. and Mahtabi, Mohammad Javad and Mills, Michael J. and Elahinia, Mohammad and others},
title = {Effect of hatch spacing and laser power on microstructure, texture, and thermomechanical properties of laser powder bed fusion (L-PBF) additively manufactured NiTi},
annote = {This study systematically evaluates the effects of laser powder bed fusion additive manufacturing (L-PBF-AM) parameters (hatch spacing and laser power) on the thermomechanical behavior and microstructure of Ni50.8Ti49.2 shape memory alloy. The samples were fabricated with hatch spacings from 40 to 240 µm and laser powers of 50 and 100 W at a constant scanning speed of 125 mm/s, resulting in parts with volumetric energy density levels from 55 to 666 J/mm3 and two sets of linear energy densities of 0.4 and 0.8 J/mm. The results showed a reduced melt pool size and discontinuity of scan tracks with decreased laser power. Additionally, the porosity level was increased with larger hatch spacing and lower laser power. More notably, the transformation temperatures increased, and the critical stress, recoverable strain, and functional stability of samples improved with lower hatch spacing, where the recovery ratio of up to 90% was observed, regardless of the employed laser power. This study also discussed the relationship between the fabrication process and texture formation in the L-PBF-AM process. In conclusion, the advantage of L-PBF-AM was revealed in tailoring the microstructure from highly textured samples in [1 1 1] or [0 0 1] direction when hatch spacing lower than laser beam focused was employed, to the appearance of equiaxed solidification front with island grains and random orientations.},
doi = {10.1016/j.optlastec.2021.107680},
url = {https://www.osti.gov/biblio/1977524},
journal = {Optics and Laser Technology},
issn = {ISSN 0030-3992},
number = {C},
volume = {149},
place = {United States},
publisher = {Elsevier},
year = {2021},
month = {11}}
Haberland, Christoph; Elahinia, Mohammad; Walker, Jason
ASME 2013 Conference on Smart Materials, Adaptive Structures and Intelligent Systems, Volume 1: Development and Characterization of Multifunctional Materials; Modeling, Simulation and Control of Adaptive Systems; Integrated System Design and Implementationhttps://doi.org/10.1115/SMASIS2013-3070