Papers by Keyword: Ti6Al4V

Abstract: Investigating how two different ceramic additives affect the microstructure and nanomechanical characteristics of the Ti6Al4V matrix forms the goal of this work. Under 50 MPa pressure, 10 min dwell time, and 100 °C/min sintering rate at 950 °C, a pulsed electric current sintering process, or PECS, was used. An XRD spectrometer was used to examine the phases, and SEM-EDS was used to examine the bulk morphology of the starting powders and sintered composites. The fabricated Cs1, Cs2, and Cs3 composites attained theoretical densities of 99.74, 98.90, and 96.7%, respectively, above 96.22% of unreinforced Ti-alloy. The SEM analysis showed an even dispersion of the ceramic reinforcements in the matrix of Ti6Al4V, with the characteristics of porous craters in all the samples. Of the three composite samples, Cs1 showed the highest elastic modulus, micro, and nanohardness absolute values of 173 GPa, 796 MPa, and 8942 MPa, respectively, as compared to the unreinforced titanium alloy of 114 GPa, 589 MPa, and 6466 MPa. It was thought that the improved mechanical properties of the sintered composites were due to the production of intermediate phases of Ti₂N and SiO₂ during the sintering process. The materials improvement stands at approximately 30% of the unreinforced Ti-alloy.

Abstract: The technological advancements in laser powder bed fusion (PBF-LB/ L-PBF) processing has led to the potential in utilizing larger powder bed layer thicknesses aimed at increasing the productivity. Moreover, by increasing the layer thickness, coarser powder particle size distribution (PSD) may be employed, further improving cost-effectiveness of the process. This drives the shift towards a more sustainable process chain, while reinforcing the business cases in additive manufacturing (AM). In this study, the effect of larger layer thickness (i.e., 90 µm) using recommended PSD of 15 to 45 µm, as well as feedstock powder with a coarser PSD (i.e., 45 to 90 µm) on the surface characteristics, heat treated microstructure, and mechanical properties of Ti64 components is evaluated. The results were then compared with that of 30 and 60 µm layer thicknesses, using a standard PSD of 15 to 45 µm.

Abstract: This work is part of a project that aims to carry out industrial research on recovery of metallic Ti6Al4V waste material through the generation of recycled powders for their incorporation into the feedstock (in granular form) of extrusion based additive manufacturing processes. Preliminary printing tests show that commercially available 3D printing extrusion-based systems are ineffective at printing granules with particle sizes below 100 μm. Thus, a novel material extrusion screw-based 3D printing extrusion head is designed and tested with granular feedstock of different particle size distributions (1-100, 1-400, 100-475 and 475-550 μm). By means of this novel system, granular feedstock with sizes between 1 and 475 μm was successfully employed for the printing of green Ti6Al4V highly complex geometries. Critical printing parameters were investigated and optimized, demonstrating the feasibility of the incorporation of recycled Ti6Al4V powders into thermoplastic feedstocks for material extrusion additive manufacturing processes.

Abstract: This study examines the wear behavior of Ti6Al4V following nanosecond pulse laser surface texturing (LST) using 15 W power, 60 kHz frequency, and 180 mm/s speed. Tested under dry sliding conditions with a 20 N load, 0.3 m/s speed, and 900 s duration, LST produced melt bulges that enhanced surface wear resistance. This study demonstrates that nanosecond pulse laser surface texturing on Ti6Al4V significantly enhances wear resistance, reducing wear rate by 3% and coefficient of friction by 5%.

Abstract: Titanium alloys are highly valued in various industries due to their exceptional qualities. This study examines how the build orientation affects the mechanical and fatigue properties of Laser Powder Bed Fusion (PBF-LB) produced Ti6Al4V, without heat treatment. The research shows mechanical properties vary based on build orientation with vertically oriented specimens exhibiting the highest yield and tensile strengths, while vertical orientation excels in ductility, measured through elongation at break. Impact toughness sees variations with horizontal orientation performing the best. However, build orientation has minimal influence on flexural bending fatigue performance. Both diagonal and vertical orientations show similar fatigue limits at around 40 MPa. Dry electropolishing proves to be an effective technique, significantly enhancing fatigue performance with limits stabilizing at about 150 MPa. This study underscores the importance of considering build orientation in PBF-LB manufacturing for specific mechanical and impact properties and the potential of dry electropolishing in improving the fatigue performance of Ti6Al4V components. These findings offer valuable insights for the additive manufacturing industry, aiding in the optimization of Ti6Al4V component production.

Abstract: While additive manufacturing of metals has been rapidly growing industry for the past decade, the quality and the fatigue properties of the materials are still not very well known. In this study, we focus on the laser powder bed fusion (PBF-LB) manufactured Ti6Al4V. The as built material was compared to the heat treated counterpart by microstructural analysis, and the mechanical properties, impact toughness and the fatigue strength were determined. Bending fatigue testing was conducted for both as built and polished material to reveal the effect of surface roughness. The results showed that the heat treatment and the resulting microstructural change is crucial for the material properties and the material showed very brittle behaviour without it. According to the results, the surface quality plays also an important role in the fatigue life of the material, especially if no heat treatment is used.

Abstract: Lattice structures and Topology Optimization are two of the main routes to design lightweight high resistance components. These design techniques often lead to complex geometries not obtainable by traditional manufacturing. In this work we show how Additive Manufacturing (AM) of metals can be a successful way to reach that result. At first, we studied Ti6Al4V samples produced by Electron Beam Melting (EBM) to determine the mechanical properties of the base material. Hot Isostatic Pressing (HIP) was performed on a part of these samples to understand the impact of this process on defects and material properties. The results we obtained showed that the properties of Ti6Al4V produced by EBM are comparable to the one of the conventionally produced one. Given these results we redesigned an automobile’s lower control arm to reduce its mass: considering both Topology Optimization (TO) and lattice structures. Ti6Al4V components with different lattice structures were successfully manufactured by EBM.

Abstract: Metal powder bed fusion additive manufacturing technologies are increasingly being adopted in industrial applications, but their widespread implementation on an industrial scale is hindered by the high manufacturing cost. This study investigates two strategies to improve the build rate of Ti-6Al-4V alloy processed by powder bed fusion using a laser beam (PBF-LB/Ti6Al4V), which is a critical factor that affects the cost of an additive manufacturing part. The first strategy involves increasing the layer thickness from 30 µm to 60 µm, while the second strategy entails increasing the particle size of the raw material from 25-45 µm to 45-106 µm while maintaining a layer thickness of 60 µm.The experiment involved modifying the process parameters based on the energy density (J/mm2), combining laser powers between 180-470 W, scanning speeds between 600-2611 mm/s, and distance between passes from 0.12 to 0.21 mm. With the highest density level process parameter combinations, a comparative study of manufacturing times for a given geometry showed a productivity improvement of up to 50%. The static mechanical properties of the specimens were evaluated by performing tensile tests. The roughness of the melt was determined for each strategy. The study concludes that modification of process parameters can reduce the build rate of PBF-LB/Ti6Al4V while maintaining its tensile strength and surface roughness.

Abstract: Laser Surface Texturing (LST) has demonstrated to be the most reliable technique for the micro-modification of surfaces, allowing to obtain taylored surfaces. These modifications, depending on the basic micro-geometry and its repetition pattern, can provide special functionalities to a surface, such as hydrophilicity, hydrophobicity, reflectance, anti-bacterial, ostheo-integrability, as well as custom aesthetic, among others.Nevertheless, when a laser irradiates metallic surfaces, the micro-structure can be modified due to the heat induced, changing the mechanical properties of the surface. To avoid these effects, cold or ultra-short pulsed lasers must be used.A cold laser emits optical pulses with a duration below 1 ps (ultra-short pulses), in the domain of femtoseconds (fs=10^-15 s). These ultra-short pulses, combined with high frequencies, in the megahertz region, leads to pulse trains with high repetition rates. This allows the sublimation of the material, keeping it relatively cold due to the short exposition time to irradiation.Ti6Al4V is the most used Ti alloy, thanks to its excellent weight/mechanical properties ratio. Nevertheless, its tribological behavior is very poor. Although there is intense research to improve it by using LST, the study of the influence of femtosecond laser parameters in the desired micro-geometries is still a gap in the scientific literature.In this research, a study of the influence of power (up to 50 W) and frequency (up to 2 MHz) in the fs-laser texturing of Ti6Al4V is presented. Local pulse repetition, linear and surface textures have been studied by combining power and frequency in these ranges, evaluating the geometry obtained by variable focus microscopy. The study carried out has allowed to determine the optimal set of parameters as a function on the target texture geometry, as well as the range in which the LST removal process changes from sublimation (for texturing) to melting (for micro-machining).

Abstract: The industrial and engineering applications of Titanium alloys has increased in the recent times particularly in automobile and aerospace industries. Ultrasonic machining of titanium alloys is one of the developments in the recent times to counter the poor machinability characteristics of Ti alloys. In this work, ultrasonic vibration assisted turning is adopted in machining Ti6AL4V with cutting speed, feed rate, depth of cut and amplitude as process parameters. Cutting force, cutting temperature and surface roughness are considered as performance evaluators. The role of each process parameter on each of the responses is evaluated and the optimum parametric combination for multi objective optimization is determined using Grey Relational Analysis. The results are interpreted with respect to tool work contact ratio. It was concluded from the experimental analysis that cutting force, cutting temperature and surface roughness depend on the TWCR which in turn depends on cutting speed and amplitude of vibration. Low TWCR revealed better performance whereas the effect of ultrasonic vibration is found to be reduced with increment in TWCR. In addition, feed rate and depth of cut are found to be significant in effecting the multi response characteristic (GRG).