Browsing by Keyword "Ti-6Al-4V"
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Item Accuracy and Surface Quality Improvements in the Manufacturing of Ti-6Al-4V Parts Using Hot Single Point Incremental Forming(2019-06) Ortiz, Mikel; Penalva, Mariluz; Iriondo, Edurne; López de Lacalle, Luis Norberto; FABRIC_INTELThe present work focuses on the manufacturing of Ti-6Al-4V parts using hot single point incremental forming (SPIF), a non-conventional forming technology mainly oriented toward the fabrication of prototypes, spare parts, or very low volume series. In the used procedure, the entire sheet is heated and kept at uniform temperature while the tool incrementally forms the part, with the limited accuracy of the obtained parts being the major drawback of the process. Thus, this work proposes two approaches to improve the geometric accuracy of Ti-6Al-4V SPIF parts: (i) correct the tool path by applying an intelligent process model (IPM) that counteracts deviations associated with the springback, and (ii) skip overforming deviations associated with the deflection of the sheet along the perimeter of the part based on a design improvement. For this purpose, a generic asymmetric design that incorporates features of a typical aerospace Ti-6Al-4V part is used. The results point out the potential of both solutions to significantly improve the accuracy of the parts. The application of the IPM model leads to an accuracy improvement up to 49%, whereas a 25.4% improvement can be attributed to the addendum introduction. The geometric accuracy study includes the two finishing operations needed to obtain the part, namely decontamination and trimming.Item Characterization of Ti-6Al-4V modified by nitrogen plasma immersion ion implantation(1997-09) Alonso, F.; Rinner, M.; Loinaz, A.; Oñate, J. I.; Ensinger, W.; Rauschenbach, B.; Centros PRE-FUSION TECNALIA - (FORMER); Tecnalia Research & InnovationT1-6Al-4V alloy is commonly used in biomedical or aerospace applications, due to its excellent combination of chemical and mechanical properties, such as bioinertness, corrosion resistance or high strength to weight ratio. The use of surface treatments or coatings has widened the application possibilities of this alloy. The often observed poor tribological performance can be overcome by the correct choice of surface engineering methods. Ion implantation is a candidate among the different available processes and excellent results have been obtained in biomedical applications. However, when complex geometries are involved, it can be a difficult and less economically effective treatment. Plasma immersion ion implantation (PIII) offers the possibility of performing three-dimensional ion beam treatments, reducing the need for manipulation under vacuum to obtain a uniform treatment of geometrically complex parts. In this work, PIII was used to implant nitrogen in the Ti-6Al-4V alloy. The nitrogen plasma was generated with a 2.45 GHz microwave excitation, and a pulsed bias voltage of 45 kV with pulse repetition rates of 50 and 400 Hz were applied. Nitrogen retained doses were evaluated by means of Rutherford backscattering spectroscopy (RBS). Pin-on-disc wear and friction tests were performed on the implanted samples. An ultra high molecular weight polyethylene pin was used as the counterface material to partially simulate the conditions encountered in biomedical applications. A reasonable improvement in load bearing capacity with respect to the unimplanted alloy was observed after these tribological tests. However, no hardening could be measured after ion implantation. The worn surfaces were observed by scanning electron microscopy and optical profilometry after the tests and the type of wear mechanism was studied. The effect of the implantation was to increase the load at which breakthrough occurred on the protective surface layer.Item Effect of ERS process parameters on the microstructure and mechanical properties of Ti6Al4V(European Powder Metallurgy Association (EPMA), 2019) Amigó-Mata, A.; Gouvea, Eber; Lagos, M. A.; López, D.; Jesús-Romero, I.; Agote, I.; Vicente-Escuder, A.; Calero, J. A.; EXTREMATThe application of the Electric Resistance Sintering (ERS) process has the advantage of rapid densification and sintering, but it needs to analyse the influence of the parameters on the microstructure and final mechanical properties in a titanium alloy. In an ERS equipment, different current intensities will be applied to atomized powders of Ti-6Al-4V using the commercial pure Ti (CP) with the same parameters as the reference material. Its effect on the microstructure obtained along the thickness of the sample will be analysed. The mechanical characteristics will be determined by tensile and cantilever bending tests, together with maps of microhardness distribution that allows relating the mechanical behaviour with the microstructure applying backscattered electron diffraction techniques (EBSD).Item Hot Single Point Incremental Forming of Ti-6Al-4V Alloy(Trans Tech Publications Ltd, 2014) Ortiz, Mikel; Penalva, Mariluz; Puerto, Mildred J.; Homola, Petr; Kafka, Václav; FABRIC_INTEL; FACTORYThe lightweight metal alloy Ti-6Al-4V is widely used in the aeronautical industry due to its excellent mechanical properties. However, it is known the difficulty to deform Ti-6Al-4V sheets at room temperature because of its microstructure conditions. The present work focuses on the evaluation of formability of Ti-6Al-4V sheets using hot single point incremental forming (SPIF) process which it seems appropriate to produce small batches of parts due to its flexibility as it allows a significant reduction of costs and lead times. In order to characterize the SPIF of Ti-6Al-4V under hot forming conditions, a set of forming trials evaluation tests was carried out. The obtained results have allowed identifying the key process features and have demonstrated the potential of the proposed approach to hot form of small amounts of Ti-6Al-4V parts.Item Mechanical properties and structure of Ti-6A1-4V alloy implanted with different light ions(1995-10) Alonso, F.; Arizaga, A.; Quainton, S.; Ugarte, J. J.; Viviente, J. L.; Oñate, J. I.; Centros PRE-FUSION TECNALIA - (FORMER); TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOS; Tecnalia Research & InnovationThe effect of N+ and C- implantation on the properties of Ti-6Al-4V alloy is widely documented. However, some authors claim that other light ions, such as O+ or B+, also have an effect on this alloy, improving its mechanical properties. In this work, Ti-6Al-4V alloy samples have been implanted with C+, N+ and O+ light ions. Energies from 50 to 180 keV and doses of the order of 1017 ion cm-2 have been used, keeping the substrate temperature below 500°C. Mechanical properties such as the hardness or elastic recovery have been evaluated by means of microindentation tests, with a loading-unloading cycle at loads up to 10 mN. An increase in surface hardness of more than 100% has been observed in most of the implanted samples. Pin-on-disc wear tests under lubricated conditions have been performed to evaluate and compare the tribological behaviour of implanted samples against ultrahigh molecular weight polyethylene. A decrease in the friction coefficient from 0.1 to 0.05, resulting from ion implantation, has been observed. Unlubricated wear tests using an alumina ball on a Ti-6Al-4V disc have also been carried out. Wear tracks on the Ti-6Al-4V, evaluated by means of optical profilometry and scanning electron microscopy, have shown that implantation can improve the abrasive wear resistance by two orders of magnitude. X-ray photoelectron spectroscopy analyses also were carried out on selected samples, showing the presence of hard phases, such as oxides or carbides, in the implanted samples.