PSI - Issue 56

S Anand Kumar et al. / Procedia Structural Integrity 56 (2024) 65–70 / Structural Integrity Procedia 00 (2019) 000–000

69 3

3.3 Microhardness The size of the prior β grains of the Ti6Al4V gradually grows with the stress -relieving heat treatment process. The hardness profile across the welded samples in the as-built condition and the stress-relieving state is shown in Fig. 4. From the hardness profile, the hardness of the as-built sample is higher than that of the stress-relieved samples. Hence, the SR treatment helped relieve the residual stresses in the material due to the LPBF process.

Fig. 4 Microhardness profile of the as-printed condition and SR condition

4. Conclusions 1. The as-built sample produced by the LPBF reveals long columnar grain in the weld regions, which grow by cladding multiple layers and are oriented in the buildup direction. 2. In the SR heat treatment, the microstructure reveals a bright α phase along the grain boundaries. 3. The hardness was found to decrease with SR heat treatment. The hardness in the AP+SR welded samples was lower when compared to the AP+AP welded samples. References [1] Herzog, D.; Seyda, V.; Wycisk, E.; Emmelmann, C.; Additive manufacturing of metals. Acta Mater. 2016, 117, 371–392. [2] Kumar SA, Prasad RVS (2021) Chapter 2 - Basic principles of additive manufacturing: different additive manufacturing technologies. In: Manjaiah M, Raghavendra K, Balashanmugam N, Davim JP (eds) Additive Manufacturing. Woodhead Publishing, pp 17–35. [3] Pathania A, Anand Kumar S, Nagesha BK, et al (2021) Reclamation of titanium alloy based aerospace parts using laser based metal deposition methodology. Materials Today: Proceedings 45:4886–4892. https://doi.org/10.1016/j.matpr.2021.01.354. [4] Kiel-Jamrozik, M.; Szewczenko, J.; Basiaga, M.; Nowinska, K. Technological capabilities of surface layers formation on implants made of Ti-6Al-4V ELI alloy. Acta Bioeng. Biomech. 2015, 17, 31–37. [5] Kiel-Jamrozik, M.; Jamrozik, W.; Witkowska, I.; The heat treatment influence on the structure and mechanical properties of Ti6Al4V alloy manufactured by LPBF technology. Innov. Biomed. Eng. 2018, 623, 319–327. [6] Thijs, L.; Verhaeghe, F.; Craeghs, T.; Humbeeck, J.V.; Kruth, J. A study of the microstructural evolution during selective laser melting of Ti 6Al 6Al-4V. Acta Mater. 2010, 58, 3303–3312. [7] M Losertová and V Kubeš; Microstructure and mechanical properties of selective laser melted Ti6Al4V alloy, Materials Science and Engineering 266 (2017) 012009. [8] Naeem Eshawish, Savko Malinov, Wei Sha, and Patrick Walls; 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, 5290 - Volume 30(7) July 2021. [9] D. Agius, K.I. Kourousis, and C. Wallbrink, A Review of the As-Built LPBF Ti-6Al-4V Mechanical Properties Towards Achieving Fatigue Resistant Designs, Metals (Basel), 2018, 8(1), p 75.