Computational Evaluation of the Effect of Build Orientation on Thermal Behavior and in-situ Martensite Decomposition for Laser Powder-Bed Fusion (LPBF) Process

Yıl 2023, Cilt: 36 Sayı: 2, 870 - 880, 01.06.2023

Ayşe Kübra Yıldız Mehmet Mollamahmutoglu Oğuzhan Yılmaz

https://doi.org/10.35378/gujs.1028004

Öz

Laser powder bed fusion (LPBF), which is an additive manufacturing method, is a thermo-mechanical process in which instantaneously varying heat flow rates occur by moving a high-intensity laser beam. The high temperatures and cooling rates that occur throughout the process result in microstructures with brittle behavior. The microstructure and mechanical properties may be improved by controlling the cooling rates in the layers via build orientation. Since the process is on a microscale, it requires planning as it does not allow instant intervention. Therefore, numerical analysis can be helpful to determine the effect of different build orientations. In this study, the effect of different build orientations was emphasized. For this purpose, successive layers resulting in narrowing and expanding cross-sectional areas were investigated with a detailed thermal approach. Also, a martensite decomposition case, as a result of changing the build orientation for a geometry, was presented numerically. As a result, it is shown that build orientation has an effect on the heat distribution within the part. Some benefits of expanding the cross-sectional area have been determined. Specifically, it is found that the build orientation may also enable local martensite decomposition, contributing to a lamellar microstructure.

Anahtar Kelimeler

Laser powder bed fusion, Ti6Al4V, Build orientation, Martensite decomposition, Modelling

Kaynakça

• [1] Eshawish, N., Malinov, S., Sha, W., Walls., P., “Microstructure and mechanical properties of Ti-6Al-4V manufactured by selective laser melting after stress relieving, hot isostatic pressing treatment, and post-heat treatment”, Journal of Materials Engineering and Performance, 30, 5290–5296, (2021).
• [2] Taylor, H.C., Garibay, E.A., Wicker, R.B., “Toward a common laser powder bed fusion qualification test artifact”, Additive Manufacturing, 39, 101803, (2020).
• [3] Kruth, J.P., Badrossamay, M., Yasa, E., Deckers, J., Thijs, L., Humbeeck, J. “Part and material properties in selective laser melting of metals”, 16th International Symposium on Electromachining, ISEM 2010, (2010).
• [4] Mfusi, B.J., Tshabalala, L.C., Popoola, A.P.I., Mathe, N.R., “The effect of selective laser melting build orientation on the mechanical properties of AlSi10Mg parts”, 2018 IOP Conference Series Materials Science and Engineering, 430, 012028, (2018).
• [5] Ren, S., Chen, Y., Liu, T., Qu, X., “Effect of Build Orientation on Mechanical Properties and Microstructure of Ti-6Al-4V Manufactured by Selective Laser Melting”, Metallurgical and Materials Transactions A, 50, 4388–4409, (2019).
• [6] Alsalla, H.H., Smith, C., Hao, L., “Effect of build orientation on the surface quality, microstructure and mechanical properties of selective laser melting 316L stainless steel”, Rapid Prototyping Journal, 24(1): 9-17, (2018).
• [7] Welsch, G., Boyer, R., Collings, E., “Materials properties handbook: titanium alloys”, ASM international, (1993).
• [8] Kim, H.Y., Miyazaki, S., “Martensitic transformation and superelastic properties of Ti-Nb base alloys”, Materials Transactions, 56, 625-634, (2015).
• [9] Zhang, X., Yocom, C.J., Mao, B., Liao, Y., “Microstructure evolution during selective laser melting of metallic materials: A review”, Journal of Laser Applications, 31, 031201, (2019).
• [10] Filip, R., Kubiak, K., Ziaja, W., Sieniawski, J., “The effect of microstructure on the mechanical properties of two-phase titanium alloys”, Journal of Materials Processing Technology, 133, 84–89, (2003).
• [11] Xu, W., Sun, S., Elambasseril, J., Liu, Q., Brandt, M., Qian, M., “Ti-6Al-4V additively manufactured by selective laser melting with superior mechanical properties”, The Minerals, Metals & Materials Society, (2015).
• [12] Xu, W., Brandt, M., Sun, S., Elambasseril, J., Liu, Q., Latham, K., Xiad, K., Qian, M., “Additive manufacturing of strong and ductile Ti–6Al–4V by selective laser melting via in situ martensite decomposition”, Acta Materialia, 85, 74–84, (2015).
• [13] Xu, W., Lui, E.W., Pateras, A., Qjan, M., Brandt, M., “In situ tailoring microstructure in additively manufactured Ti-6Al-4V for superior mechanical performance”, Acta Materialia, 125, 390-400, (2017).
• [14] Boyer, R, Welsch, G., Collings, E.W., “Materials properties handbook: titanium alloys”, ASM International, ISBN 978-0871704818, Materials Park, OH, (1994).
• [15] Mills, K.C., “Recommended values of thermophysical properties for selected commercial alloys”, first ed., Woodhead Publishing Ltd, (2002).
• [16] Gong, X., Cheng, B., Price, S., Chou, K., “Powder-bed electron-beam-melting additive manufacturing: powder characterization, process simulation and metrology”, ASME Early Career Technical Conference (ECTC), District F, 59-66, (2013).
• [17] Fan, Z., Liou, F., “Numerical modeling of the additive manufacturing (am) processes of titanium alloy. in: titanium alloys-towards achieving enhanced properties for diversified applications”, first edition, IntechOpen, (2012).
• [18] Parry, L., Ashcroft, I.A.R., Wildman, D., “Understanding the effect of laser scan strategy on residual stress in selective laser melting through thermo-mechanical simulation”, Additive Manufacturing, 12, 1-15, (2016).
• [19] Riedlbauer, D., Scharowsky, T., Singer, R.F., Steinmann, P., Körner, C., Mergheim, J., “Macroscopic Simulation and Experimental Measurement of Melt Pool Characteristics in Selective Electron Beam Melting of Ti-6Al-4V”, The International Journal of Advanced Manufacturing Technology, 88, 1309–1317, (2016).
• [20] Mollamahmutoglu, M., Yilmaz, O., Unal, R., Gumus, B., Tan, E., “The effect of evaporation and recoil pressure on energy loss and melt pool profile in selective electron beam melting”, The International Journal of Advanced Manufacturing Technology, (2022).
• [21] Gu, H., Gong, H., Dilip, J.J.S, Pal, D., Hicks, A., Doak, H., Stucker, B., “Effects of powder variation on the microstructure and tensile strength of ti6al4v parts fabricated by selective laser melting”, 25th annual international solid freeform fabrication symposium, (2014).
• [22] Mollamahmutoğlu, M., Yılmaz, O., “Volumetric heat source model for laser-based powder bed fusion process in additive manufacturing”, Thermal Science and Engineering Progress, 25, 101021, (2021).
• [23] Yıldız, A. K., Mollamahmutoğlu, M., Dogan, E., Yılmaz, O., “A numerical investigation of the effect of support thickness and void ratio on thermal behavior and possible martensite decomposition in laser powder-bed fusion process”, Journal of Additive Manufacturing Technologies, 1(2), 549, (2021).
• [24] Salsi, E., Chiumenti, M., Cervera, M., “Modeling of microstructure evolution of Ti6Al4V for additive manufacturing”, Metals, 8, 633, (2018).
• [25] Ahmed, T., Rack, H.J., “Phase transformations during cooling in α+β titanium alloys”, Materials Science and Engineering: A, 243, 206–211, (1998).
• [26] Gan, M.X., Wong, C.H., “Practical support structures for selective laser melting,” Journal of Materials Processing Technology, 238, 474-484, ISSN 0924-0136, (2016).