Papers by Keyword: Ti6Al4V

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Authors: Gideon C. Obasi, R.J. Moat, D. G. Leo Prakash, W. Kockelmann, Joao Quinta da Fonseca, Michael Preuss
Abstract: In the present study, in situ phase transformation experiments have been carried out using neutron diffraction to monitor the texture evolution during the α→ß→α phase transformation in Ti-6Al-4V with and without 0.4% yttrium additions. The aim of adding yttrium was to control ß grain growth above the transus ß by grain boundary pinning. In the present case, strengthening of the ß texture, occurring during ß grain coarsening resulted in strengthening of particular ß texture components, which increases the likelihood of α texture modification by selective growth of α variants on the common (110) ß grain boundaries into unoccupied large β grains.
Authors: Yu Ling Yang, Wei Yan, Duo Zhang, Gen Zong Song, Yi Ran Zheng
Abstract: The insitu-fabrication of TiCN ceramic coating by laser cladding-laser nitriding technique (LC-LN) was investigated. Pulsed YAG laser with the power of 500W was used as radiation source. Highly pure N2 was selected as the nitriding element; Titanium powder whose size is 20 m and the pure carbon powder were utilized as the coating materials. The influence of technology parameters such as pulse width, pulse frequency and scanning speed etc. on the insitu-formation of TiCN ceramic coating was studied. XRD results show that the main phases of the coating are TiC0.3N0.7 (or TiC0.2N0.8),TiN and TiN0.3. It was revealed that the appropriate process parameters for insitu-fabrication are the pulse frequency 15 Hz, pulse width 3.0ms, the scanning speed in the range of 9cm/min to 12cm/min, the pressure of N2 0.4MPa. The result of OM showed a metallurgical bonding without crack and bubble between the coating and the substrate was obtained. The microstructure of cladded coating is characterized by fine dentrites. The average microhardness in the coating is more than 1300HV which is about 4 times of that in the substrate.
Authors: Chi Sheng Chien, Yu Sheng Ko, Tsung Yuan Kuo, Tze Yuan Liao, Ting Fu Hong, Tzer Min Lee
Abstract: Hydroxyapatite (HA) is a frequently used bioactive coating material. However, when HA coating is soaked in the simulated body fluid (SBF), it is usually detached from substrate material due to its high dissolution rate in the solution. Recently, it is found that Fluorapatite (FA) has a better anti-dissolution ability than HA. In this study, Fluorapatite was mixed with TiO2 powder (either Anatase phase (A) or Rutile phase (R)) as a coating material precursor, and then be deposited on Ti-6Al-4V substrate to form the coating layer by using Nd-YAG laser cladding process. After soaking in SBF for various days, it is observed that dense ball-like apatite grew faster on the surface of the FA+R coating layer than that on the surface of the FA+A specimens. The corresponding Ca/P ratios of FA+R specimens also dropped faster than FA+A ones.
Authors: Hassan Zamani, Jan Patrick Hermani, Bernhard Sonderegger, Christof Sommitsch
Abstract: During machining of hard materials, one approach to reduce tool wear is using a laser beam to preheat the material in front of the cutting zone. In this study, a new concept of laser-assisted milling with spindle and tool integrated laser beam guiding has been tested. The laser beam is located at the cutting edge and moving synchronously with the cutter. In experiment, a reduction in the resulting process cutting forces and tool wear has been observed in comparison to milling without laser. A three-dimensional finite element model in DEFORM 3D was developed to predict the cutting forces in the milling process with and without an additional laser heat source, based on a Johnson-Cook-type material constitutive model adapted for high strains and strain rates. Both in experiment and simulation, the deformation behavior of a Ti-6Al-4V workpiece has been investigated. The comparison of the resulting cutting forces showed very good agreement. Thus the new model has great potential to further optimize laser assisted machining processes.
Authors: Zhi Meng Chen, Jian Fu Zhang, Ping Fa Feng, Zhi Jun Wu
Abstract: The cutting force, cutting temperature and mechanisms are studied by Finite Element Method during the orthogonal metal cutting of Ti-6Al-4V with micro-textured cutting tools. The relation between the texture’s antifriction effect and the parameter of the textures is analyzed. The Derivative-Cutting phenomenon is found when cutting Ti-6Al-4V using textured tools. The mechanisms about how the micro-textured tools change the frictional behavior in the chip-tool interface are explained using Derivative-Cutting characteristic. The antifriction performance of micro-textured cutting tools in the metal cutting process is discussed. The cutting force and cutting temperature is decreased effectively in the cutting simulation with the micro-textured tools manufactured in reasonable parameters.
Authors: Afshin Mohammadhosseini, Darren Fraser, S.H. Masood, Mahnaz Jahedi
Abstract: Electron beam melting (EBM) has been recognized as a revolutionary manufacturing process. This layer-by-layer additive manufacturing process has shown great promise for fabrication of biomedical implants and aerospace components. This paper represents an investigation into the particle size distribution, morphology and flow-ability of Ti6Al4V powder used in EBM process. The effect of recycling of the powder on the chemical properties has been investigated. Results show that recycling increases the weight percentage of interstitial elements. The flow-ability and apparent density of the powder were measured before and after recycling process and no change was observed.
Authors: S. Samsudeensadham, Vijayan Krishnaraj
Abstract: The heat produced in metal cutting process is one of the most critical issue in machining of titanium alloys. High temperature in metal cutting degrades the tool life, surface integrity, size accuracy and machining efficiency dramatically. The temperature generated during end milling of titanium alloy, has been measured using Thermo camera. Surface roughness plays a vital role in evaluating and measuring the quality of the machined surface. During the experiments, cutting speed and feed rate have been changed to analyse the effect of temperature and surface roughness. It is observed that cutting speed has the greater effect on temperature and surface roughness during end milling of titanium alloy. The regression equations generated have better fit which can be used for optimization.
Authors: Chun Xiang Gao
Abstract: A very effective approach to improve the oxidation resistance of Ti-6Al-4V alloy was proposed. The Ti-6Al-4V alloy was firstly phosphated and then coated by silica using sol-gel dip-coating technique. A duplex layer of TiP2O7 and amorphous silica was synthesized at the alloy surface. The isothermal and cyclic oxidation behavior of the treated alloy with silica coating and the corresponding bare alloy was investigated at 600 oC in static air to investigate the synergetic effect of phosphorization and amorphous SiO2 coating on the oxidation resistance of the alloy. The isothermal and cyclic oxidation resistances of the alloy were greatly improved.
Authors: Denison Baldo, Sergio Luiz Moni Ribeiro Filho, Carlos Henrique Lauro, Andrea Cristiane dos Santos Delfino, Lincoln Cardoso Brandao
Abstract: This work shows a study on the micro milling of Ti-6Al-4V Titanium alloy where the effect of tool wear on the surface finish of the machined part was analyzed. New and worn micro cutters were applied to produce grooves with 0.5 mm of width and 0.025 mm of heights. The surface roughness was measured in the Ra and Rz values and the results showed that the surface roughness was not influenced by the tool’s condition. However, when new tools were used the increase of cutting speed generated an improving of the surface roughness and the same effect occurred with the decrease of feed rate.
Authors: Nitin Kotkunde, Aditya D. Deole, Amit Kumar Gupta, Swadesh Kumar Singh
Abstract: In this work, deep drawing experiments have been performed in order to study formability of Ti-6Al-4V alloy sheet at temperature ranging from room temperature to 4000C. It is found that below 1500C, formability of the material is very poor and above 1500C till 4000C, limiting draw ratio (LDR) is found to be 1.8 which is substantially lesser than other structural alloys such as austenitic stainless steels. In order to understand qualitative aspects of formability, thickness distribution of drawn cup has been evaluated experimentally over a temperature range of 1500C - 4000C. Additionally, Finite Element (FE) analysis is done using a commercially available code Dynaform version 5.6.1 with LS-Dyna version 971 solver. 3-Parameter Barlat yield model is used for FE analysis. Predicted thickness distribution using FE simulation is in good agreement with experimental results.
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