Commercially pure titanium (CP-Ti) has received a great deal of attention in medical applications. Improvement of its mechanical properties plays a key role in enhancing the biomechanical ...compatibility of Ti implants, leading to avoid revision surgeries. Emerging advanced manufacturing technologies such as selective laser melting (SLM) is providing an ideal platform for producing components with almost no geometric constraints and is economically feasible down to a batch size of one. This study presents the results of using SLM to produce CP-Ti parts starting from powder with a wide grain size range up to 100μm. Accurate manipulation of SLM manufacturing parameters were applied to produce nearly full dense (>99.5%) CP-Ti parts without any post-treatments. Compared with the properties of those manufactured by traditional processing technologies, the microhardness, compressive, and tensile strengths of SLM-processed CP-Ti parts have been improved to 261Hv, 1136MPa, and 757MPa, respectively, due to the formation of refined martensitic α′ grains during SLM. The optimal manufacturing parameters could enhance the strength and hardness of CP-Ti and yet maintaining the ductility of titanium. Fractography study of the tensile-failed SLM-processed specimens showed that incompletely melted particles and porosities caused early fracture in porous sample. Mixture of dimples and minor quasi-cleavage facets covered most fracture surface of full dense sample.
Electricity consumption prediction plays a vital role in intelligent energy management systems, and it is essential for electricity power supply companies to have accurate short and long-term energy ...predictions. In this study, a deep-ensembled neural network was used to anticipate hourly power utilization, providing a clear and effective approach for predicting power consumption. The dataset comprises of 13 files, each representing a different region, and ranges from 2004 to 2018, with two columns for the date, time, year and energy expenditure. The data was normalized using minmax scalar, and a deep ensembled (long short-term memory and recurrent neural network) model was used for energy consumption prediction. This proposed model effectively trains long-term dependencies in sequence order and has been assessed using several statistical metrics, including root mean squared error (RMSE), relative root mean squared error (rRMSE), mean absolute bias error (MABE), coefficient of determination (R2), mean bias error (MBE), and mean absolute percentage error (MAPE). Results show that the proposed model performs exceptionally well compared to existing models, indicating its effectiveness in accurately predicting energy consumption.
Ti and Ti-TiB composite materials were produced by selective laser melting (SLM). Ti showed an α΄ microstructure, whereas the Ti-TiB composite revealed a distribution of needle-like TiB particles ...across an α-Ti matrix. Hardness (H) and reduced elastic modulus (Er) were investigated by nanoindentation using loads of 2, 5 and 10 mN. The results showed higher H and Er values for the Ti-TiB than Ti due to the hardening and stiffening effects of the TiB reinforcements. On increasing the nanoindentation load, H and Er were decreased. Comparison of the nanoindentation results with those derived from conventional hardness and compression tests indicated that 5 mN is the most suitable nanoindentation load to assess the elastic modulus and hardness properties. The wear resistance of the samples was related to their corresponding H/Er and H3/Er2 ratios obtained by nanoindentation. These investigations showed that there is a high degree of consistency between the characterization using nanoindentation and the wear evaluation from conventional wear tests.
A group of Ti--xNb--7Fe (x=0, 1, 4, 6, 9, 11wt.%) alloys was designed and produced by cold crucible levitation melting process. The microstructural characteristic of the alloys with Nb addition and ...its effect on their mechanical properties as well as wear resistance were investigated. Microscopic and phase analysis results show that all the alloys, except for the Ti--11Nb--7Fe, exhibit orthorhombic alpha " and body-centred cubic beta phases, while Ti--11Nb--7Fe alloy consists of only beta phase. It is proposed that increasing the Nb content enhances beta phase stability and its proportion in the microstructure of the designed alloys. Depending on the proportion of beta and alpha " phases, Ti--xNb--7Fe alloys show varied hardness (3.57-5.92GPa) and compressive strength (1990-2093MPa). Additionally, they present wear rates in the range of 310-15-110-13 m3/m which correlates well with the changes in the corresponding microstructures and mechanical properties. Among the studied alloys, Ti--11Nb--7Fe with beta phase microstructure, presents the lowest elastic modulus (86GPa) and the highest compressive strain (41.5%) along with high compressive strength, hardness and wear resistance. Therefore, it is suggested that this beta -type Ti--11Nb--7Fe alloy is a promising candidate, more suitable than the commercially used CP--Ti and Ti--6Al--4V, for orthopedic applications.
Commercially pure titanium (CP-Ti) and Ti–TiB composite parts with three different porosity levels (i.e. 10%, 17% and 37%) were produced by selective laser melting (SLM). Scanning electron microscopy ...(SEM) investigations show that martensitic (α′) microstructure exists in SLM-processed CP-Ti parts, whilst SLM-processed Ti–TiB composites present needle-shape TiB particles distributed in α-Ti matrix. Mechanical properties of these porous samples decrease with porosity level increasing. The yield strength and elastic modulus of porous CP-Ti parts range 113–350MPa and 13–68GPa respectively, which are much lower than those for porous Ti–TiB counterparts (234–767MPa and 25–84GPa respectively) mainly due to the strengthening effect induced by TiB particles in Ti–TiB samples. Compression stress–strain curves of 37% porous CP-Ti parts show a typical three-stage behavior of ductile porous metals. Also, the elastic moduli of both 37% porous CP-Ti and Ti–TiB samples are similar to that of human bone. SEM investigations of the porous CP-Ti samples after compression testing show that no crack presents until 50% compressive strain and most of deformation is absorbed by porous areas. In contrast, μ-CT investigations indicate that all porous Ti–TiB samples fail at early stages of compression testing due to cracks resulting from insufficient ductility of struts of porous areas, because they are not able to accommodate high strains of the deformation at high strengths.
Commercially pure titanium, as a widely used metallic biomaterial, was fabricated using dissimilar additive manufacturing (AM) methods, namely selective laser melting (SLM), laser engineered net ...shaping (LENS) and wire arc additive manufacturing (WAAM). Microstructures as well as mechanical and wear properties of the produced titanium samples were studied. Diverse microstructural features were related to the different linear energy densities and cooling rates induced by each AM method. Tensile testing evaluation indicated the highest yield and ultimate tensile strengths as well as elastic energy for titanium produced by SLM. However, the maximum ductility was obtained in the WAAM-fabricated titanium due to its larger grain size and slightly higher densification. All the mechanical properties obtained were either superior or comparable to those of cast and powder metallurgy produced titanium. Fracture surface analysis showed the presence of mainly coarse and fine dimples for WAAM and SLM-produced samples, respectively. This was consistent with the grain size of each sample. Wear performances and mechanisms were also examined and the results were in agreement with the values obtained from the hardness to elastic modulus ratios (H/E and H3/E2).
Highly-dense bulk Cu–10Sn bronze specimens have been fabricated by selective laser melting (SLM) and their (micro)structure and mechanical properties have been investigated and compared with the ...corresponding material produced by casting. Room-temperature tensile tests reveal that yield and ultimate strengths increase from 120 and 180MPa for the cast samples to 220 and 420MPa for the specimens processed by SLM. Material strengthening is accompanied by a significant improvement of ductility, which increases from 7 to 17%. This behavior can be ascribed to the refined microstructure of the SLM material resulting from the high cooling rate imposed by laser processing, further demonstrating the effectiveness of SLM for the production of materials with enhanced mechanical performance.
Display omitted
•Highly-dense Cu–10Sn bronze specimens fabricated by selective laser melting (SLM).•Refined microstructure of SLM material compared to corresponding cast samples.•Improved yield and ultimate strengths, and ductility with respect to cast material.
The present study investigates the wear properties of commercially pure titanium (CP-Ti) parts produced using selective laser melting (SLM) and casting. Scanning electron microscopy (SEM) ...investigations show that SLM-produced CP-Ti parts have martensitic (α΄) microstructure, whereas cast-produced CP-Ti samples exhibit plate-like (α) microstructure. SEM studies on the wear surfaces at moderate loads (15N) show shallow ploughing grooves at certain regions and some delamination cracks for both SLM and cast CP-Ti samples. On increasing the load to 30N, deeper ploughing grooves were observed in both samples along with delamination of material at certain regions. However, ploughing grooves were found to be very shallow in SLM samples compared with the cast parts. Although both SLM and cast CP-Ti exhibited similar wear mechanisms, SLM CP-Ti showed better wear resistance due to its martensitic microstructure, finer grain size and superior microhardness.
•Wear-properties of commercially pure-Ti prepared by SLM and casting processes.•Both samples show similar wear mechanisms.•SLM-processed sample show superior wear performance than cast specimens.•The superior wear properties are attributed to the martensitic microstructure.
The effect of chemical composition on microstructure and tensile properties of a series of low modulus Ti-Nb-Cu-Ni-Al alloys was studied. These alloys consist of primary micrometer-sized β-Ti ...dendrites surrounded by intermetallic phases. The morphology of the intermetallic phases is strongly affected by composition. Due to the composite microstructure, the alloys exhibit a low Young's modulus (77–84GPa) together with a high yield strength of about 1000MPa as well as moderate tensile ductility. The results demonstrate that complete substitution of Al by Ti reduces the Young's modulus by 5%. Increasing Nb content at the expense of Ti causes a significant improvement of tensile ductility.
High strength beta titanium alloys: New design approach Okulov, I.V.; Wendrock, H.; Volegov, A.S. ...
Materials science & engineering. A, Structural materials : properties, microstructure and processing,
03/2015, Volume:
628
Journal Article
Peer reviewed
A novel approach for development of high strength and ductile beta titanium alloys was proposed and successfully applied. The microstructure of the designed alloys is fully composed of a bcc beta -Ti ...phase exhibiting dendritic morphology. The new Ti68.8Nb13.6Cr5.1Co6Al6.5 (at%) alloy (BETAtough alloy) exhibits a maximum tensile strength of 1290 plus or minus 50MPa along with 21 plus or minus 3% of fracture strain. The specific energy absorption value upon mechanical deformation of the BETAtough alloy exceeds that of Ti-based metallic glass composites and commercial high strength Ti-based alloys. The deformation behavior of the new alloys was correlated with their microstructure by means of in-situ studies of the microstructure evolution upon tensile loading in a scanning electron microscope.
PDF
