Page 359 - IJB-10-1

International Journal of Bioprinting Corrosion behavior of SLM-prepared 316L steel

it was still lower than that observed for sample 20, even be the differences in the microstructures and corrosion
when considering the standard deviations; see Table 3). resistances if the AM-prepared material is swaged
The slight increase in the CR for sample 15 (compared under cold conditions? What will be the differences
to sample 17) is attributed to the fact that the increased between the final properties if the original workpiece
imposed strain induced annihilation of dislocations and is prepared in a different manner? What combinations
formation of subgrains. In other words, the dislocation of processing methods and selected parameters
density was slightly reduced when compared to sample 17, will offer the most satisfactory results? How do the
and moreover, the fraction of the newly formed subgrain microstructural features change after the samples are
boundaries, i.e., LAGBs, was slightly increased within the subjected to a corrosive environment? These are some
structure of sample 15, providing increased volume of of the questions for guiding our future research.
possible nucleation sites for corrosion.

Investigations on the behavior of swaged samples, 5. Conclusion
from the viewpoint of pitting corrosion, also offered The present study primarily focused on the correlation
intriguing findings. As evident from Table 3, the E of corrosion behavior with microstructure and residual
pit
parameter, i.e., critical pitting potential, increased to its stress for AISI 316L stainless steel workpieces prepared by
maximum observed value after swaging to 17 mm, and combinations of additive manufacturing (SLM) and hot
then dropped significantly (to its minimum observed rotary swaging (RS, variable swaging ratios); corrosion
value) after swaging to 15 mm. Abbasi Aghuy et al. testing was performed in an i-SBF. The main conclusions
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documented that the grain size has only a negligible derived from this study are summarized as follows:
effect on the pitting potential of austenitic stainless steels,
which is in accordance with the results presented herein. The combination of SLM and RS produced relatively
On the other hand, the presence of (fiber) texture affects fine-grained microstructures with predominantly
the pitting corrosion significantly . The texture analyses compressive residual stress states in the axial direction
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showed that sample 17 exhibited a strong {111}||SD states.
texture fiber. In other words, the {111}||ND and {111}||TD Increasing the swaging ratio contributed to
texture orientations, which were reported by others to homogenization of grain size distribution.
be preferential for the development of pitting corrosion The highest texture intensity ({111}||SD fiber) was
within austenitic stainless steels , were the least intense
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within sample 17. This most probably contributed to observed for the sample subjected to the swaging ratio of
the resistance of sample 17 to pitting corrosion, despite 0.8; increasing the swaging ratio to 1.1 imparted structure
the fact that this sample featured a well-developed restoration related to annihilation of dislocations and
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dislocation substructure . The substantial decrease in the development of subgrains.
E parameter for sample 15 was most probably attributed Homogeneity and intensity of residual stress depended
pit
to the accumulated internal energy imposed by the strongly on the swaging ratio, and the predominantly
increased swaging ratio, and the decrease in the intensity compressive stress state imparted by RS enhanced the
of the {111}||SD preferential texture orientation. As corrosion potential.
regards sample 20, its relatively high resistance to pitting A high intensity of {111}||SD texture fiber increased the
corrosion was most probably attributed to the low density critical pitting potential.
of lattice defects, as proven by the results of substructure
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and KAM analyses . The most favorable corrosion behavior was observed for
the sample subjected to the swaging ratio of 0.8, primarily
Rotary swaging is generally known for its versatility,
which is concerned with the possibility to alter the due to a high intensity of the {111}||SD texture fiber, fine
grain size, and high density of dislocations.
applied strain paths, thereby affecting the (sub)
structure development during processing. In the Acknowledgments
present study, we applied a processing route during
which the workpiece entered the anvils in each pass in The authors would like to acknowledge the help of
an identical manner, i.e., with no rotation between the Dr. Marek Pagáč (VŠB-TUO, CZ), Zdeněk Jakůbek,
passes. Nevertheless, rotating the workpiece between Denisa Beranová, and the LaPaMat laboratory team
the passes can affect the activated slip systems . A few (all Institute of Physics of Materials, Czech Academy
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questions thus arise: Will alternations of the applied of Sciences, Czech Republic). Neutron diffraction
strain paths have any effects on the corrosion behavior measurements were done at CANAM infrastructure of
of AM-prepared 316L steel workpieces? Also, what will Nuclear Physics Institute.

Volume 10 Issue 1 (2024) 351 https://doi.org/10.36922/ijb.1416