Effect of post-heat treatment with super β transus temperature on the damping behaviour of LPBF-processed Ti6Al4V thin rotor blade Akshay Pathania, Anand Kumar S., Nagesha B.K., Sanjay Barad Proceedings of the Institution of Mechanical Engineers Part L Journal of Materials Design and Applications, 2025 This article investigates the damping behaviour of laser powder bed fusion-processed Ti6Al4V thin plate samples and thin rotor blades. The effect of microstructural changes owing to the post heat treatments (PHTs – 850 °C, 950 °C and 1050 °C) on damping behaviour was assessed. The microstructural characterisation was performed using optical microscopy, X-ray diffraction and scanning electron microscope techniques. The impact hammer test was performed on thin plate samples and rotor blades to characterise damping behaviour. The microstructure of the thin plate samples subjected to PHT conditions varied in grain structure and morphology compared to the as-printed ones. Further, PHT at a higher temperature (i.e. 1050 °C) induces a higher amount of β phase than the other PHT temperatures. The PHT performed at 1050 °C exhibited α- Widmanstätten microstructure consisting of elongated β and a small amount of α. Moreover, the frequency response function plots revealed broader peaks for thin plate samples and the rotor blade than others. The PHT was favourable in enhancing the α lath thickness and β volume fraction, increasing the damping ratio. The results showed that PHT performed at 1050 °C improves the overall damping of ∼348% and ∼140% of rotor blade and thin plate samples, respectively. The amplitude decay for the rotor blade subjected to PHT at 1050 °C was ∼66% shorter than the as-printed one due to high β phase content relieving the energy resulting in a high damping ratio.
Influence of post-heat treatment on microstructure, mechanical, and wear properties of maraging steel fabricated using direct metal laser sintering technique Anand Kumar Subramaniyan, Sudarshan Reddy Anigani, Snehith Mathias, Akshay Pathania, Prasad Raghupatruni, Shubhendra S Yadav Proceedings of the Institution of Mechanical Engineers Part L Journal of Materials Design and Applications, 2025 The post-heat treatment of direct metal laser sintered parts is expected to have superior mechanical properties. Therefore, the purpose of the present study is to investigate the post-heat treatment effect on the microstructure, mechanical and wear properties of direct metal laser sintering processed maraging steel. Hence, a systematic methodology for microstructural characterization, mechanical properties, and tribological performance evaluation was performed. The microstructural examinations were performed using optical and scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction technique. The micro-hardness and tensile properties were determined. The unidirectional sliding wear test was performed using a pin on disc wear testing machine for three different sliding velocities (0.8, 1.2, and 1.6 m/s) and three different normal loads (5, 10, and 15 N). The present study’s findings establish that the post-heat treatment techniques significantly altered the microstructural morphology and features. The results showed that the heat-treated sample had finer and non-continuous microstructure and more complex intermetallic precipitate phases, leading to higher hardness (∼64%) and higher tensile strength properties (70–80%) compared to the as-printed sample. The unidirectional sliding wear test results showed that the sliding velocity significantly affected frictional and wear characteristics of direct metal laser sintering processed maraging steel. The wear resistance of the heat-treated sample was three times higher than the as-printed sample, particularly at higher sliding velocities. In addition, the lower coefficient of friction values (∼24%) was observed for heat-treated sample compared to as-printed sample at higher sliding velocities. The post-heat treatment aids as an effective method to enhance mechanical properties of direct metal laser sintered parts and qualify them for tribological applications. The results endorse the suitability of the heat-treated direct metal laser sintered maraging steel in practical tool and die applications involving extreme tribological operating conditions such as higher sliding velocities and contact stresses.
Influence of post-heat treatment with super β transus temperature on the tensile behaviour of LPBF processed Ti6Al4V Akshay Pathania, S Anand Kumar, BK Nagesha Proceedings of the Institution of Mechanical Engineers Part E Journal of Process Mechanical Engineering, 2025 This paper investigates the tensile behaviour of Laser powder bed fusion (LPBF) processed Ti6Al4 V samples under three build orientations. The effect of microstructural changes from the post-heat treatments (PHTs – 850 °C, 950 °C 1050 °C) was assessed. The microstructural characterization was performed using optical microscopy, X-ray diffraction, and SEM techniques. The tensile tests were performed using a uniaxial universal testing machine (UTM). The fractal dimension analysis was performed on the fractured surfaces using ImageJ software integrated with an open-source MultiFrac plug-in. The PHT at a higher temperature (i.e., 1050 °C) induces a higher amount of β phase than the other PHTs. The PHT performed at 1050 °C exhibited α-Widmanstatten microstructure consisting of elongated β and a small amount of α. The PHT induces an isotropic behaviour in the LPBF-processed samples. However, the ductility of specimens subjected to PHT at 1050 °C showed ∼ 67%, 40%, and 177% improvement under horizontal (0°), inclined (45°), and vertical (90°) orientations than as-printed samples. Further fractal dimension analysis corroborates well with the ductility values of PHT samples. Therefore, the combination of fractography analysis and fractal dimension approach can be a promising methodology towards fractured surface characterization of additively manufactured metal parts.
Skin-Core Scanning Strategy in LPBF Processed Ti6Al4V: Effects on Microstructure and Microhardness Akshay Pathania, Anand Kumar Subramaniyan, Nagesha Bommanahalli Kenchappa Materials Performance and Characterization, 2023 ABSTRACT The skin-core scanning strategy in the present study was employed to observe microstructural changes in laser powder bed fusion processed Ti6Al4V. The microstructural characterization was carried out using optical microscopy and microhardness tests were performed. The microstructural investigation indicated that the skin region had a 34 % smaller grain size than the core region, and the presence of α martensite needles. Because of the finer grains, the microhardness values were marginally higher on the skin than in the core region. The current study’s findings open a pathway to tailor functional and architectured microstructures with desired mechanical properties for end-use critical applications.
