Eİ ile Üretilen SİP Uygulanmış Ti6Al4V Numunelerde Gözeneklilik Ölçümü – Arşimet Yöntemi ve MikroBT arasında Pratik bir Karşılaştırma

Abstract

Bu çalışma Arşimet Yöntemi ve Mikro-BT (Bilgisayarlı Tomografi) ile boşluk/gözenek ölçümünün karşılaştırmalı bir incelemesini sunmaktadır. Eklemeli imalat (Eİ) ile üretilen Ti6Al4V numuneler 3 farklı Sıcak İzostatik Presleme (SİP) parametresiyle ardıl işleme tabi tutulmuş olup, bir grup da işlemsiz olarak bırakılmıştır. Toplam numune sayısı 16’dır ve her grup 4 numune ile temsil edilmiştir. Daha iyi mekanik özelliklere ulaşılabilmesi için süreç optimizasyonu ile mümkün olan en yüksek bağıl yoğunluğa (%100) ulaşılması ve kusurların morfolojisinin optimizasyonu hedeflenmektedir. SİP, numunelerin yoğunluğunu artırma bir diğer deyişle içindeki boşluğu en aza indirme ya da tamamen ortadan kaldırma konusunda öne çıkan ardıl işlem seçeneklerinden biridir. Tipik olarak işlemsiz numunelerdeki yoğunluk %99’un üzerinde çıkmaktadır. Özellikle yorulma dayanımı açısından malzemenin içindeki boşluklar, bu boşlukların yapısı ve dağılımı da çok önemlidir. Bu çalışmada, ilk grup olarak 920°C-100MPa-2 saat SİP, ikinci grup olarak 815°C-190 MPa-2 saat SİP, üçüncü grup olarak 920°C-100MPa-2 saat SİP ve ardından hızlı soğutma uygulanmış olup, dördüncü grup da işlemsiz olarak bırakılmıştır. Her numunenin yoğunluğu Arşimet Yöntemi’yle ölçülmüş ve her gruptan da 1 adet numuneye Mikro-BT yapılmıştır. Sonuçlar karşılaştırılmış ve bu iki yöntem arasında göreceli bir korelasyon bulunmuştur. Arşimet Yöntemi boşluk seviyesini ölçmek için hızlı ve ekonomik bir yöntemdir. Mikro-BT ise numune içindeki boşlukların konumlarını ve formlarını da tespit edebilme özelliğiyle Arşimet Yöntemi’nden ayrışmaktadır.

Keywords

• Eklemeli İmalat
• Sıcak İzostatik Presleme
• Boşluk
• Arşimet Yöntemi
• Mikro-BT

Porosity Measurement for HIPped AM Ti6Al4V Samples – A Practical Comparison between Archimedes Method and Micro-CT

Abstract

This study presents a comparative analysis of porosity measurement techniques using the Archimedes method and micro-computed tomography (Micro-CT) for additively manufactured (AM) Ti-6Al-4V components. The samples were subjected to four different post-processing conditions: three groups were processed using Hot Isostatic Pressing (HIP) with varying parameters, while one group remained in the as-built condition. A total of 16 samples were analyzed, with each group comprising four specimens. To enhance the mechanical performance of AM parts, particularly their fatigue strength, maximizing relative density (approaching 100%) and optimizing the morphology of the defects are primary objectives. Among post-processing techniques, HIP is one of the most effective methods for reducing or eliminating internal porosity, thereby increasing the overall density of as-built materials, which typically exhibit densities exceeding 99% of the theoretical value. The presence, morphology, and distribution of porosity are especially critical in determining fatigue behavior. The experimental setup included: Group 1: HIP at 920 °C, 100 MPa, for 2 hours, Group 2: HIP at 815 °C, 190 MPa, for 2 hours, Group 3: HIP at 920 °C, 100 MPa, for 2 hours with uniform rapid quenching, and Group 4: As-built condition (no post-processing) Density measurements were performed on all samples using the Archimedes method. Additionally, one representative sample from each group was partially scanned using Micro-CT to evaluate internal porosity characteristics. A comparative analysis of the results from both techniques revealed a consistent correlation between them. While the Archimedes method offers a faster, more cost-effective approach for quantifying overall porosity levels, Micro-CT provides valuable insights into the spatial distribution, size, and morphology of pores within the material—information that cannot be captured through the Archimedes technique alone.

Keywords

• Additive Manufacturing
• Hot Isostatic Pressing
• Porosity
• Archimedes Method
• Micro-CT

References

1. [1] M. J. Donachie, Titanium: a technical guide, 2nd ed. Materials Park, OH: ASM International, 2000.
2. [2] C. Leyens and M. Peters, Eds., Titanium and titanium alloys: fundamentals and applications. Weinheim: Wiley-VCH, 2005.
3. [3] B. Dutta and F. H. Froes, Additive Manufacturing of Titanium Alloys. Elsevier, 2016. doi: 10.1016/C2015-0-02470-4.
4. [4] G. Kasperovich and J. Hausmann, “Improvement of fatigue resistance and ductility of TiAl6V4 processed by selective laser melting,” J. Mater. Process. Technol., vol. 220, pp. 202–214, 2015, doi: 10.1016/j.jmatprotec.2015.01.025.
5. [5] J. A. Slotwinski, E. J. Garboczi, and K. M. Hebenstreit, “Porosity Measurements and Analysis for Metal Additive Manufacturing Process Control,” J. Res. Natl. Inst. Stand. Technol., vol. 119, p. 494, 2014, doi: 10.6028/jres.119.019.
6. [6] D. R. Gillum, Industrial pressure, level, and density measurement, 2nd ed. Research Triangle Park, NC: International Society of Automation, 2009.
7. [7] S. Bai, N. Perevoshchikova, Y. Sha, and X. Wu, “The Effects of Selective Laser Melting Process Parameters on Relative Density of the AlSi10Mg Parts and Suitable Procedures of the Archimedes Method,” Appl. Sci., vol. 9, no. 3, p. 583, 2019, doi: 10.3390/app9030583.
8. [8] M. A. Buhairi et al., “Review on volumetric energy density: influence on morphology and mechanical properties of Ti6Al4V manufactured via laser powder bed fusion,” Prog. Addit. Manuf., vol. 8, no. 2, pp. 265–283, 2023, doi: 10.1007/s40964-022-00328-0.

9. [9] J. Schröder, T. Fritsch, B. Ferrari, M. L. Altmann, G. Bruno, and A. Toenjes, “Laser powder bed fusion: Defect type influences critical porosity re-growth during reheating after hot isostatic pressing,” J. Mater. Process. Technol., p. 118839, 2025, doi: 10.1016/j.jmatprotec.2025.118839.
10. [10] B. Naab and M. Celikin, “The role of microstructural evolution on the fatigue behavior of additively manufactured Ti–6Al–4V alloy,” Mater. Sci. Eng. A, vol. 859, p. 144232, 2022, doi: 10.1016/j.msea.2022.144232.
11. [11] S. Tammas-Williams, P. J. Withers, I. Todd, and P. B. Prangnell, “The Influence of Porosity on Fatigue Crack Initiation in Additively Manufactured Titanium Components,” Sci. Rep., vol. 7, no. 1, p. 7308, 2017, doi: 10.1038/s41598-017-06504-5.
12. [12] S. Siddique, M. Imran, M. Rauer, M. Kaloudis, and E. Wycisk, “Computed tomography for characterization of fatigue performance of selective laser melted parts,” Mater. Des., vol. 83, pp. 661–669, 2015, doi: 10.1016/j.matdes.2015.06.063.
13. [13] A. M. Khorasani, I. Gibson, A. Ghasemi, and A. Ghaderi, “A comprehensive study on variability of relative density in selective laser melting of Ti-6Al-4V,” Virtual Phys. Prototyp., vol. 14, no. 4, pp. 349–359, 2019, doi: 10.1080/17452759.2019.1614198.
14. [14] R. Cunningham et al., “Analyzing the effects of powder and post-processing on porosity and properties of electron beam melted Ti-6Al-4V,” Mater. Res. Lett., vol. 5, no. 7, pp. 516–525, 2017, doi: 10.1080/21663831.2017.1340911.
15. [15] S. McConnell, Y. Beshay, K. Kourousis, and D. Tanner, “Increasing productivity for laser powder bed fusion of Ti–6Al–4V parts through increased layer thickness,” Prog. Addit. Manuf., 2025, doi: 10.1007/s40964-025-01079-4.
16. [16] A. R. Johnsen, J. E. Petersen, M. M. Pedersen, and H. C. Yıldırım, “Factors affecting the fatigue strength of additively manufactured Ti-6Al-4V parts,” Weld. World, vol. 68, no. 2, pp. 361–409, 2024, doi: 10.1007/s40194-023-01604-5.
17. [17] R. Reiff-Musgrove et al., “Effect of Relatively Low Levels of Porosity on the Plasticity of Metals and Implications for Profilometry‐Based Indentation Plastometry,” Adv. Eng. Mater., vol. 24, no. 12, p. 2200642, 2022, doi: 10.1002/adem.202200642.
18. [18] A. Du Plessis, I. Yadroitsava, and I. Yadroitsev, “Effects of defects on mechanical properties in metal additive manufacturing: A review focusing on X-ray tomography insights,” Mater. Des., vol. 187, p. 108385, 2020, doi: 10.1016/j.matdes.2019.108385.
19. [19] E. Stevens, S. Schloder, E. Bono, D. Schmidt, and M. Chmielus, “Using Microscopy and Image Analysis to Show Density and Property Variations in Additive Manufactured Ti-6Al-4V,” Microsc. Microanal., vol. 25, no. S2, pp. 2590–2591, 2019, doi: 10.1017/S1431927619013680.
20. [20] M. Sangali, A. Cremasco, J. Soyama, R. Caram, and R. J. Contieri, “Selective Laser Melting of Ti-6Al-4V Alloy: Correlation Between Processing Parameters, Microstructure and Corrosion Properties,” Mater. Res., vol. 26, no. suppl 1, p. e20230055, 2023, doi: 10.1590/1980-5373-mr-2023-0055.
21. [21] A. T. R. Carvalho, “Development and Characterization of Titanium Alloys Processed by Laser Powder Bed Fusion for Biomedical Applications,” Master Thesis, University of Lisbon, Physics Department, Lisbon, Portugal, 2024.
22. [22] E. Westphal and H. Seitz, “Porosity and density measurement of additively manufactured components: A comparative analysis of measurement methods across processes and materials,” Mater. Sci. Addit. Manuf., vol. 4, no. 2, p. 025090010, 2025, doi: 10.36922/MSAM025090010.
23. [23] D. A. Renzo et al., “X-ray computed μ-tomography analysis to evaluate the crack growth in an additive manufactured Ti-6Al-4V alloy sample stressed with in-phase axial and torsional loading,” Int. J. Fatigue, vol. 175, p. 107727, 2023, doi: 10.1016/j.ijfatigue.2023.107727.
24. [24] A. Du Plessis and E. Macdonald, “Hot isostatic pressing in metal additive manufacturing: X-ray tomography reveals details of pore closure,” Addit. Manuf., vol. 34, p. 101191, 2020, doi: 10.1016/j.addma.2020.101191.
25. [25] A. Thompson, I. Maskery, and R. K. Leach, “X-ray computed tomography for additive manufacturing: a review,” Meas. Sci. Technol., vol. 27, no. 7, p. 072001, 2016, doi: 10.1088/0957-0233/27/7/072001.
26. [26] H. Gong, V. K. Nadimpalli, K. Rafi, T. Starr, and B. Stucker, “Micro-CT Evaluation of Defects in Ti-6Al-4V Parts Fabricated by Metal Additive Manufacturing,” Technologies, vol. 7, no. 2, p. 44, 2019, doi: 10.3390/technologies7020044.
27. [27] Y. Mao, J. Hu, Q. Chen, and X. Shen, “Quantitative Analysis of the Physical Properties of Ti6Al4V Powders Used in a Powder Bed Fusion Based on 3D X-ray Computed Tomography Images,” Materials, vol. 17, no. 4, p. 952, 2024, doi: 10.3390/ma17040952.
28. [28] E. Uhlmann, R. Kersting, T. B. Klein, M. F. Cruz, and A. V. Borille, “Additive Manufacturing of Titanium Alloy for Aircraft Components,” Procedia CIRP, vol. 35, pp. 55–60, 2015, doi: 10.1016/j.procir.2015.08.061.
29. [29] H. Hassanin et al., “Optimising Surface Roughness and Density in Titanium Fabrication via Laser Powder Bed Fusion,” Micromachines, vol. 14, no. 8, p. 1642, 2023, doi: 10.3390/mi14081642.
30. [30] F. Zanini, E. Sbettega, and S. Carmignato, “X-ray computed tomography for metal additive manufacturing: challenges and solutions for accuracy enhancement,” Procedia CIRP, vol. 75, pp. 114–118, 2018, doi: 10.1016/j.procir.2018.04.050.
31. [31] A. Zatočilová, T. Zikmund, J. Kaiser, D. Paloušek, and D. Koutný, “Measurement of the Porosity of Additive-Manufactured Al-Cu Alloy Using X-Ray Computed Tomography,” Solid State Phenom., vol. 258, pp. 448–451, 2016, doi: 10.4028/www.scientific.net/SSP.258.448.
32. [32] A. B. Spierings, M. Schneider, and R. Eggenberger, “Comparison of density measurement techniques for additive manufactured metallic parts,” Rapid Prototyp. J., vol. 17, no. 5, pp. 380–386, 2011, doi: 10.1108/13552541111156504.