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Development of Diffraction Research Methodologies for Mediloy S-CO Alloy Speciments Made Using LPBF Additive Manufacturing

Elżbieta Gadalińska
Elżbieta Gadalińska
, 
Maciej Malicki
Maciej Malicki
, 
Anna Trykowska
Anna Trykowska
 y 
Grzegorz Moneta
Grzegorz Moneta
   | 13 may 2024
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Publicado en línea: 13 may 2024
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DOI: https://doi.org/10.2478/fas-2023-0006
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© 2023 Elżbieta Gadalińska et al., published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Fig. 1.

The printed specimens of all 3 directions and all 5 printing sets. The specimens printed in the direction parallel to their axis (row a), inclined 45° to their axis (row b), and perpendicular to their axis (row c).
The printed specimens of all 3 directions and all 5 printing sets. The specimens printed in the direction parallel to their axis (row a), inclined 45° to their axis (row b), and perpendicular to their axis (row c).

Fig. 2.

Temperature change during heat treatment.
Temperature change during heat treatment.

Fig. 3.

Effect of specimen etching with: a) H2O2 solution in hydrochloric acid, (etchant no. 22 according to Kundra, 2023): 100ml HCl + 0.5ml H2O2 (30%)), b) H2O2 solution in hydrochloric acid (ref. no. 22 according to Kundra, 2023): 100ml HCl + 0.5ml H2O2 (30 %)) – electrolytic etching at 4V, c) 10% aqueous solution of oxalic acid – electrolytic etching at 6 V, d) 38% aqueous solution of hydrochloric acid – 3h etching, e) and f) 60 ml HNO3+ 40 ml H2O solution (ref. no. 219 according to Kundra, 2023) – electrolytic etching at 1 V – polarized light image, g) Nital 2% (etchant no. 74 according to Kundra, 2023) – electrolytic etching at 8 V, h) solution of 6.5 ml HCl + 1.5 ml HNO3 + 1.8 g CH3COOH + 1.17 ml H2O.
Effect of specimen etching with: a) H2O2 solution in hydrochloric acid, (etchant no. 22 according to Kundra, 2023): 100ml HCl + 0.5ml H2O2 (30%)), b) H2O2 solution in hydrochloric acid (ref. no. 22 according to Kundra, 2023): 100ml HCl + 0.5ml H2O2 (30 %)) – electrolytic etching at 4V, c) 10% aqueous solution of oxalic acid – electrolytic etching at 6 V, d) 38% aqueous solution of hydrochloric acid – 3h etching, e) and f) 60 ml HNO3+ 40 ml H2O solution (ref. no. 219 according to Kundra, 2023) – electrolytic etching at 1 V – polarized light image, g) Nital 2% (etchant no. 74 according to Kundra, 2023) – electrolytic etching at 8 V, h) solution of 6.5 ml HCl + 1.5 ml HNO3 + 1.8 g CH3COOH + 1.17 ml H2O.

Fig. 5.

X-ray diffractogram obtained for the specimen before heat treatment with the Braggs reflections indexed.
X-ray diffractogram obtained for the specimen before heat treatment with the Braggs reflections indexed.

Fig. 4.

Microstructure of specimen no. 1 (a, b), no. 2 (c, d), no. 3 (e, f), no. 4 (g, h), no. 5 (i, j).
Microstructure of specimen no. 1 (a, b), no. 2 (c, d), no. 3 (e, f), no. 4 (g, h), no. 5 (i, j).

Fig. 6.

X-ray diffractogram obtained for the specimen after heat treatment with the Braggs reflections indexed: the yellow square corresponds to reflections of the cubic Co3O4 phase and the green stars to reflections of the hexagonal Cr0.8Co0.2 phase.
X-ray diffractogram obtained for the specimen after heat treatment with the Braggs reflections indexed: the yellow square corresponds to reflections of the cubic Co3O4 phase and the green stars to reflections of the hexagonal Cr0.8Co0.2 phase.

Fig. 7.

Results of stress measurements in the circumferential direction before heat treatment: a) for specimens with printing direction along the specimen axis, b) for specimens printed at an angle of 45° with respect to their axis, c) for specimens printed in a direction perpendicular to their axis.
Results of stress measurements in the circumferential direction before heat treatment: a) for specimens with printing direction along the specimen axis, b) for specimens printed at an angle of 45° with respect to their axis, c) for specimens printed in a direction perpendicular to their axis.

Fig. 8.

Results of stress measurements in the axial direction before heat treatment: a) for specimens with printing direction along the specimen axis, b) for specimens printed at an angle of 45° with respect to their axis, c) for specimens printed in a direction perpendicular to their axis.
Results of stress measurements in the axial direction before heat treatment: a) for specimens with printing direction along the specimen axis, b) for specimens printed at an angle of 45° with respect to their axis, c) for specimens printed in a direction perpendicular to their axis.

Fig. 9.

Results of stress measurements in the circumferential direction after heat treatment: a) for specimens with printing direction along the specimen axis, b) for specimens printed at an angle of 45° with respect to their axis, c) for specimens printed in a direction perpendicular to their axis.
Results of stress measurements in the circumferential direction after heat treatment: a) for specimens with printing direction along the specimen axis, b) for specimens printed at an angle of 45° with respect to their axis, c) for specimens printed in a direction perpendicular to their axis.

Fig. 10.

Results of stress measurements in the axial direction after heat treatment: a) for specimens with printing direction along the specimen axis, b) for specimens printed at an angle of 45° with respect to their axis, c) for specimens printed in a direction perpendicular to their axis.
Results of stress measurements in the axial direction after heat treatment: a) for specimens with printing direction along the specimen axis, b) for specimens printed at an angle of 45° with respect to their axis, c) for specimens printed in a direction perpendicular to their axis.

j.fas-2023-0006.tab.003

etching method observations see Fig. 3
H2O2 solution in hydrochloric acid (etchant no. 22 according to Bhavar et al. (2017): 100 ml HCl + 0.5 ml H2O2 (30%)). Promising results: the ability to distinguish grains based on the shade of their colors. Intense etching of melt boundaries and lack of etching of grain boundaries prevents their precise determination. a
H2O2 solution in hydrochloric acid (ref. no. 22 according to Bhavar et al. (2017): 100 ml HCl + 0.5 ml H2O2 (30 %)) – electrolytic at 4 V. Intensive etching of melt boundaries, grain boundaries invisible. b
Kalling’s etchant 1 and 2. Etching effects were not obtained. -
10% aqueous solution of oxalic acid – electrolytic etching at 6 V Etching of melt boundaries, grain boundaries invisible. c
38% aqueous solution of hydrochloric acid. A 10-minute etching first extracted the boundaries of the melts. A 3-hour etching revealed grains, but there is difficulty in precisely defining their boundaries. d
60 ml HNO3 + 40 ml H2O solution (ref. no. 219 according to Bhavar et al., 2017) – electrolytic etching at 1 V. Promising results for observations with polarized light (the ability to distinguish grains based on the shade of their colors). Intense etching of melt boundaries and lack of etching of grain boundaries prevents their precise determination. e, f
Berach’s etchant III with the addition of sodium pyrosulfate (1 g per 100 ml). No apparent etching effects were obtained.
Nital 2% (etchant no. 74 according to Kundra, 2023) – electrolytic etching at 8 V. Etched melt boundaries in the first place, no etching of grain boundaries. Inability to distinguish between grains. g
solution of 6.5 ml HCl + 1.5 ml HNO3 + 1.8 g CH3COOH + 1.17 ml H2O. Promising results for observations with polarized light (the ability to distinguish grains based on the shade of their colors). Intense etching of melt boundaries and lack of etching of grain boundaries prevents their precise determination. h

Chemical composition of Mediloy S-Co alloy.

Co Cr Mo W Si
63.9 % 24.7 % 5 % 5.4 % <1 %

Printing parameters, energy densities and porosities for all parameter sets.

Printing parameters set no. Laser power [W] Scanning speed [mm/s] Single layer thickness [mm] Hatch spacing [mm] Energy density [J/mm3] Porosity [%]
1 optimized parameter set 119.8 0.05%
2 95 1000 0.35 0.09 30.2 8.06%
3 120 1200 0.03 0.075 44.4 1.60%
4 70 1200 0.02 0.105 27.8 16.81%
5 145 800 0.02 0.06 151.0 Ref.

Phase analysis results for the specimen after heat treatment.

phase ICDD card no. structure space group lattice parameters [Å] %
Cr0.8Co0.2 01-071-7109 hexagonalP63/mmc194 a0 = b0 = 2.52c0= 4.062 44.5
W0.04Co0.96 04-003-2727 hexagonalP63/mmc194 a0 = b0= 2.523c0 = 4.083 16.4
W0.12Co0.88 04-003-2728 cubic FCCFm-3m225 a0 = 3.586 6.8
Co304 04-014-7747 cubicFd-3m227 a0 = 8.1773 32.3

Phase analysis results for the specimen before heat treatment.

phase ICDD card no. structure space group lattice parameters [Å] %
W0.12Co0.88 04-003-2728 cubic FCCFm-3m225 a0 = 3.586 73.7
Cr0.38Co0.62 04-002-1030 hexagonalP63/mmc194 a0 = b0 = 2.53c0 = 4.08 12.4
Co 04-006-8066 hexagonalP63/mmc194 a0 = b0 = 2.052c0 = 4.09 11.4
Mo Co3 04-004-3529 hexagonalP63/mmc194 a0 = b0 = 5.1245c0 = 4.1125 2.5
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