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Item Synthesis and application of sustainable vegetable oil-based polymers in 3D printing(Royal Society of Chemistry, 2024) Saraswat, R.; Shagun, N.; Dhir, A.; Balan, A.A.S.; Powar, S.; Doddamani, M.In the past ten years, there has been significant growth in the global 3D printing market, particularly in the development of natural and bio-based polymers. However, a major challenge is the limited availability of sustainable 3D printable resins capable of matching the performance of synthetic materials. This underscores the urgent need for the development of innovative and environmentally friendly resin materials. Herein, we introduce bio-based polymers, highlighting their recent advancements and offering a comprehensive overview of their diverse applications across various fields, including 3D printing. An area that has received less attention in this domain is polymers derived from vegetable oil (VO) or plant-based oil. Specifically, we thoroughly investigate the acrylation of epoxidized VOs and the subsequent formation of resins from these acrylates, which are essential materials for digital light processing (DLP), stereolithography (SLA), and extrusion-based 3D printing. The chemical modification of VOs, such as epoxidation and acrylation, is extensively explored, together with their respective types and applications. Furthermore, we delve deeply into the suitability of acrylate resins for 3D printing purposes. In conclusion, this review offers insights into the potential applications of 3D printed products utilizing materials derived from VOs. © 2024 The Author(s).Item A comprehensive characterization of 3D printable poly ether ketone ketone(Elsevier Ltd, 2024) Ojha, N.; Kumar, S.; Ramesh, M.R.; Balan, A.A.S.; Doddamani, M.The current work focuses on the comprehensive characterization of a 3D printable biomaterial, polyether ketone ketone (PEKK). The PEKK granules are first characterized and then utilized for extrusion of the PEKK filaments. The extruded PEKK filaments are characterized for crystallinity, quality, and printability, wherein they exhibit amorphous nature, good quality, and appropriate printability. Utilizing the filaments, the samples are printed with the appropriate printing parameters, which are further characterized for layer adhesion, voids, and crystallinity, wherein they showed seamless layer adhesion, improper beads consolidation, and the amorphous nature. The as printed samples are further annealed at different temperatures (200 and 250 °C). The scanning electron microscopy (SEM) of the annealed samples (A-200 and A-250) revealed better void consolidation, while the X-ray diffraction (XRD) revealed better crystallinity compared to the un-annealed sample. The printed samples are also investigated for dynamic mechanical analysis (DMA), shape memory, and tensile properties. The storage moduli of the annealed samples are observed to be better than the un-annealed sample. The annealed samples exhibited better shape memory properties: shape fixity and shape recovery ratio of A-200 and A-250 samples, 90.28 and 90.75%, and 99.16 and 94.73%, respectively, compared to the un-annealed samples. The highest shape fixity ratio and the shape recovery ratio are noted for A-250 (90.75%) and A-200 (∼ 100%). The A-200 and A-250 samples showed enhanced tensile modulus and strength, 4.16 and 49.67%, and 36.61 and 35.06%, respectively compared to the un-annealed sample. The highest modulus is noted for A-250, while the strength is comparable (36.61 and 35.06%) for A-200 and A-250. © 2023 Elsevier LtdItem Enhancing fatigue performance of AZ31 magnesium alloy components fabricated by cold metal transfer-based wire arc directed energy deposition through LPB(KeAi Communications Co., 2024) Manjhi, S.K.; Bontha, S.; Balan, A.A.S.Cold Metal Transfer-Based Wire Arc Directed Energy Deposition (CMT-WA-DED) presents a promising avenue for the rapid fabrication of components crucial to automotive, shipbuilding, and aerospace industries. However, the susceptibility to fatigue of CMT-WA-DED-produced AZ31 Mg alloy components has impeded their widespread adoption for critical load-bearing applications. In this study, a comprehensive investigation into the fatigue behaviour of WA-DED-fabricated AZ31 Mg alloy has been carried out and compared to commercially available wrought AZ31 alloy. Our findings indicate that the as-deposited parts exhibit a lower fatigue life than wrought Mg alloy, primarily due to poor surface finish, tensile residual stress, porosity, and coarse grain microstructure inherent in the WA-DED process. Low Plasticity Burnishing (LPB) treatment is applied to mitigate these issues, which induce significant plastic deformation on the surface. This treatment resulted in a remarkable improvement of fatigue life by 42%, accompanied by a reduction in surface roughness, grain refinement and enhancement of compressive residual stress levels. Furthermore, during cyclic deformation, WA-DED specimens exhibited higher plasticity and dislocation density compared to both wrought and WA-DED + LPB specimens. A higher fraction of Low Angle Grain Boundaries (LAGBs) in WA-DED specimens contributed to multiple crack initiation sites and convoluted crack paths, ultimately leading to premature failure. In contrast, wrought and WA-DED + LPB specimens displayed a higher percentage of High Angle Grain Boundaries (HAGBs), which hindered dislocation movement and resulted in fewer crack initiation sites and less complex crack paths, thereby extending fatigue life. These findings underscore the effectiveness of LPB as a post-processing technique to enhance the fatigue performance of WA-DED-fabricated AZ31 Mg alloy components. Our study highlights the importance of LPB surface treatment on AZ31 Mg components produced by CMT-WA-DED to remove surface defects, enabling their widespread use in load-bearing applications. © 2024Item Shape memory behavior of 4D printed CF/PEKK high temperature composite under subsequent thermomechanical cycles(Elsevier B.V., 2024) Kumar, S.; Ojha, N.; Ramesh, M.R.; Balan, A.A.S.; Doddamani, M.Shape memory effect (SME) in high temperature polymers (HTPs) has great significance in space for making self-deployable structures, needing high strength and stiffness during operation, signifying the necessity of exploring HTP composite with SME. This work investigates the SME of 4D printed carbon fiber/polyether ketone ketone (CF/PEKK) HTP composite under subsequent thermomechanical cycles for the first time. Scanning electron microscopy (SEM) revealed a uniform distribution of CFs in the developed composite, the extruded composite filament, and the composite prints with seamless raster and layer deposition, confirming a suitable selection of processing parameters. The CF/PEKK composite prints exhibited an excellent shape fixity, Rf = 90 % and 91 %, and shape recovery, Rr = 96 % and 89 % in the first and the tenth cycle, respectively. A significant loss of 7 % in Rr is observed in the tenth cycle. Glass transition (Tg) and degradation temperature (Td) of the CF/PEKK composite prints are observed to be 162 °C and 568 °C, while storage modulus is found 157.69 % and 38.69 % higher than the existing PEKK and PEEK, respectively. This study revealed an excellent SME of 4D printed CF/PEKK composite with outstanding Tg and Td, showing great potential for space applications. © 2024 Elsevier B.V.Item Effect of CMT-WAAM Process Parameters on Bead Geometry, Microstructure and Mechanical Properties of AZ31 Mg Alloy(Springer, 2024) Manjhi, S.K.; Sekar, P.; Bontha, S.; Balan, A.A.S.Fabrication of Mg alloys using the additive manufacturing process is quite challenging owing to high oxidation and volatile nature at high temperatures. The present study investigates the effect of wire feed speed (WFS) and travel speed (TS) on single tracks of AZ31 Mg alloy fabricated using the cold metal transfer wire arc additive Manufacturing (CMT-WAAM) process. The WFS and TS of CMT-WAAM are optimized to achieve better deposition quality. An increase in WFS increased the width, height, penetration depth, and heat-affected zone of single tracks. In addition, increasing TS decreased the deposited tracks' contact angle and height. The average grain size at the interface zone, center and top portion of single tracks are 35, 42, and 60 μm. The x-ray diffraction results show only the presence of primary phase α-Mg; interestingly, the β-Mg17Al12 and η-Al8Mn5 secondary phases are identified by SEM + EDS and TEM images. The microhardness increased from the substrate to the top section of single tracks due to the increased volume fraction of secondary-phase particles. Based on the best-chosen process parameters obtained from single-track deposition, a multilayer AZ31 Mg thin wall is deposited. The UTS, YS, and % EL of the deposited thin wall in travel direction (TD) are 222 MPa, 102 MPa, and 18%, while in build direction are 202 MPa, 110 MPa, and 14%, respectively. The tensile strength and elongation % of TD and BD samples exhibited comparable properties and were higher than cast AZ31 Mg alloy. © ASM International 2023.Item Process parameter optimization for laser directed energy deposition (LDED) of Ti6Al4V using single-track experiments with small laser spot size(Elsevier Ltd, 2024) Gonnabattula, A.; Thanumoorthy, R.S.; Bontha, S.; Balan, A.A.S.; Anil Kumar, V.A.; Kanjarla, A.K.Single-track experiments are routinely used in the optimization of process parameters in additive manufacturing processes. Most of the process parameter optimization studies use a laser spot size of 1 mm or more. Since laser spot size affects the input energy density and in turn the efficiency of the deposition process, it is important to develop process maps every time a laser of different spot sizes is used. In this work, we determine the process maps for a laser of 0.6 mm spot size. By combining the process maps and the metallographic inspection, we estimate the optimum process parameters (laser power, scan speed, powder feed rate) for building Ti6Al4V components using powder-based laser-directed energy deposition(LDED). Single-tracks corresponding to 64 different parameter combinations are deposited. After eliminating the process parameter combinations resulting in defective tracks, the optimum process parameters of 300 W laser power and 720 mm min−1 scan speed is established by considering the relationship between the process parameters and the geometrical features of the deposit. The experimental results are then used to calibrate the modeling parameters of a three-dimensional finite element model for simulating the deposition process. © 2024 Elsevier LtdItem Effect of Build Orientation on Anisotropy in Tensile Behavior of Laser Powder Bed Fusion Fabricated SS316L(Springer, 2024) Thanumoorthy, R.S.; Chaurasia, J.K.; Anil Kumar, V.A.; Pradeep, P.I.; Balan, A.A.S.; Rajasekaran, B.; Sahu, A.; Bontha, S.In the present study, Stainless steel 316L (SS316L) cylindrical specimens were fabricated at two different build orientations and two different laser powers using Laser powder bed fusion process (LPBF). Microstructural characterization such as XRD, SEM, EBSD analysis and tensile testing were carried out on fabricated specimens in stress relieved condition to understand the anisotropic behavior of LPBF printed specimens. Horizontally oriented specimens showed higher tensile strength when compared to vertically oriented specimens for both laser powers. XRD and EBSD phase maps did not reveal the presence of any secondary phases. However, build orientation and laser power affected the crystallite size of the samples. Bimodal grain structure comprising coarse columnar grains and fine equiaxed grains were observed from the micrographs. With variation in build orientation, there was a significant change in the average grain size of the specimens. High dislocation density was observed in horizontally oriented samples built at low laser power because of dislocation annihilation that can occur at high temperatures. However, EBSD analysis revealed random weak crystallographic texture which does not vary significantly with laser power or build orientation. Variation in grain size, grain morphology, sub-grain features and dislocation density are the reasons for the anisotropic tensile behavior observed in LPBF printed SS316L coupons in stress relieved condition. © ASM International 2023.Item Effect of surface remelting on the characteristics of IN718 components fabricated using laser powder directed energy deposition(Institute of Physics, 2024) Thanumoorthy, R.S.; Jadhav, S.V.; Oyyaravelu, R.; Bontha, S.; Balan, A.A.S.Laser Powder Directed Energy Deposition (LP-DED) fabricated components exhibit poor surface finish, necessitating additional post-processing steps prior to their practical application. Enhancing the surface quality of additively manufactured IN718 specimens through conventional post-processing methods is particularly challenging, given the material’s poor machinability and the complexity of the fabricated components. The current study is centered on comprehending the impact of Laser Surface Remelting (LSR) on the surface properties of Laser Powder Directed Energy Deposited (LP-DED) IN718 material. To gain insights into how remelting influences surface characteristics, remelting was carried out using various sets of parameters. The remelted zone exhibited a refined grain structure, leading to increased hardness. Moreover, significant reductions in surface roughness and residual stress were observed in the remelted samples. Regression analysis indicated that laser power played a pivotal role, with positive impact on surface finish and depth of influence but a negative impact on residual stress and hardness. Therefore, considering all the comparison metrics, remelting using laser power of 150 W and a scan speed of 1140 mm min−1 were found to yield optimal surface conditions. © 2024 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.