PSI - Issue 56

Balichakra Mallikarjuna et al. / Procedia Structural Integrity 56 (2024) 184–189 Mallikarjuna / Structural Integrity Procedia 00 (2019) 000 – 000

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The thermal history of the six tracks as a function of time for bidirectional scanning is shown in Fig. 3(a). It can be observed that the peak temperature in the plot is 2176 °C in track 1 (From Fig. 3(a)). The temperature then attains a uniform average temperature of 1826 °C in the middle tracks (2, 3, 4, and 5). However, in the last track (track 6), the temperature increases to 1899 °C. It can be seen that the edges experience a slightly higher temperature than the middle tracks and this may contribute to higher thermal gradients at the edges. 3.3 Influence of laser power and travel speed on residual stress distribution in the plate The effect of laser power on the first Principal stress for the bidirectional scan was investigated. The Principal stress increases from 196 to 237 MPa with increased laser power (250 to 350 W) at a constant travel speed (15 mm/s). This is because the high laser power induces higher thermal gradients in the plate. Similarly, the effect of travel speeds at constant laser power on the first Principal stress for a bidirectional scan was studied. The Principal stress slightly decreases from 239 to 215 MPa as the travel speed increases from 10 to 20 mm/s at a constant laser power of 300 W. The lower exposure time reduces the thermal gradients. It can be concluded that the laser power has shown more dominance in the magnitude of residual stress formation than the travel speed. 4. Conclusion The computational modelling of directed energy deposition of TiAl plate geometries was carried out. The results indicate that the melt pool dimensions increased as the laser power increased from 250 to 350 W and decreased as the travel speed increased from 10 to 20 mm/s. The edges of the plate experienced slightly higher temperatures (track 1 2176 ℃ and track 6-1899 ℃ ) than the middle tracks. The Principal stress slightly decreases from 239 to 215 MPa as the travel speed increases from 10 to 20 mm/s at a constant laser power of 300 W. The lower exposure time reduces the thermal gradients. The laser power has shown more dominance over the magnitude of Principal stress formation than the travel speed. Acknowledgements The author thanks the Computation Fluid Dynamics Lab, National Institute of Technology Karnataka, Surathkal, India, for providing the computational facility to run the simulation. Reference Abdullah, F. M., & Anwar, S. (2020). Thermomechanical simulations of residual stresses and distortion in electron beam melting with experimental validation for Ti-6Al-4V. Metals , 10 (9), 1151. Balichakra, M., Bontha, S., Krishna, P., & Balla, V. K. (2019). Prediction and validation of residual stresses generated during laser metal deposition of γ titanium aluminide thin wall structures. Materials Research Express , 6 (10), 106550. https://doi.org/10.1088/2053 1591/ab38ee Balichakra, M., Bontha, S., Krishna, P., Das, M., & Balla, V. K. (2016). Understanding thermal behavior in laser processing of titanium aluminide alloys. Proceedings of 6th International & 27th All India Manufacturing Technology, Design and Research Conference (AIMTDR-2016) , 73 – 77. Bandyopadhyay, A. (2016). Laser engineering net shaping of microporous Ti6Al4V filters. Frontiers in Mechanical Engineering , 2 (10), 1 – 9. https://doi.org/10.3389/fmech.2016.00009 Bandyopadhyay, A., & Traxel, K. D. (2018). Invited review article: Metal-additive manufacturing-modeling strategies for application-optimized designs. Additive Manufacturing , 22 (7), 758 – 774. https://doi.org/10.1016/j.addma.2018.06.024 Bhavar, V., Kattire, P., Patil, V., Khot, S., Gujar, K., & Singh, R. (2017). A review on powder bed fusion technology of metal additive manufacturing. Additive Manufacturing Handbook: Product Development for the Defense Industry , 251 – 261. https://doi.org/10.1201/9781315119106 Diepold, B., Vorlaufer, N., Neumeier, S., Gartner, T., & Göken, M. (2020). Optimization of the heat treatment of additively manufactured Ni base superalloy IN718. International Journal of Minerals, Metallurgy and Materials , 27 (5), 640 – 648.