Production of Ti-6Al-4V alloy by 3D electron beam melting technique and development of itspost treatments

Doğu, Merve Nur
In this thesis, the effects of production variables in electron beam melting (EBM) and post-processing on the materials’ and mechanical properties of Ti-6Al-4V alloy were investigated by considering the microstructural change. Ti-alloy samples were produced at 0o, 45o and 90o with respect to building plate. Surface polishing with HF solution was applied to reduce the surface roughness. On the other hand, post-heat treatments, namely, 2-step thermo-hydrogen processing (THP) and annealing, were conducted to improve the mechanical properties, i.e. hardness and tensile strength, and to increase fatigue life. Production at different angles had no influence on texture formation such that in all samples the texture of α-phase was commonly concentrated in (101 ̅0) plane, which was parallel to building direction. The samples produced at 0o had the coarsest and lowest microstructure and hardness value, respectively, possibly due to higher heat input during production; however, they possessed comparatively higher density and lower surface roughness. Therefore, the samples displayed high tensile strength and ductility comparable to standards. Likewise, fatigue life improved by production at 0o due to lower surface roughness and defects. THP refined the microstructure and slightly increased the hardness by altering the texture. Although tensile strength increased, ductility reduced possibly due to oxidation. Annealing coarsened the microstructure and degraded the mechanical properties. On the other hand, both post heat treatment processes did not influence the fatigue life due to predominant effect of high surface roughness. Despite the reduced surface roughness by surface polishing, fatigue life decreased because of dissolved hydrogen in samples.


Optimization of the mechanical properties of Ti-6Al-4V alloy fabricated by selective laser melting using thermohydrogen processes
BILGIN, Guney Mert; Esen, Ziya; Akin, Seniz Kushan; Dericioğlu, Arcan Fehmi (2017-07-17)
2-step Thermo Hydrogen Process (THP) including hydrogenation and dehydrogenation steps was applied to Ti-6Al-4V alloy fabricated by selective laser melting (SLM) process to refine the microstructure and to increase the ductility of the alloy. It was observed that as-fabricated alloy's surface was composed of oxides of titanium and aluminum, which may alter the hydrogenation kinetics. The hydrogen treatment for 1 hat 650 degrees C, the maximum hydrogen solubility temperature of the alloy, transformed startin...
Preparation of iron oxide nanoparticles by microwave synthesis and their characterization
Acarbas, Ozge; Ozenbas, Macit (American Scientific Publishers, 2008-02-01)
In this study production of fine particle Fe2O3 via microwave processing of Fe(NO3)(3)center dot nH(2)O followed by low temperature annealing was reported. XRD was used to characterize the structural properties of nanoparticles. Approximate particle sizes were between 3-13 nm according to Scherrer's equation. Single point BET measurement results also show that samples have large surface area and they are nanometer sized particles. TEM study was conducted to examine the structure of the nanoparticles. TEM fi...
Fabrication of a promising immobilization platform based on electrochemical synthesis of a conjugated polymer
Buber, Ece; SÖYLEMEZ, SANİYE; UDUM, YASEMİN; Toppare, Levent Kamil (2018-07-01)
Since conjugated polymers are an important class of materials with remarkable properties in biosensor applications, in this study, a novel glucose biosensor based on a conjugated polymer was fabricated via the electropolymerization of the monomer 10,13-bis(4-hexylthiophen-2-yl)dipyridol[3,2-a:2',3'-c]phenazine onto a graphite electrode surface. Glucose oxidase (GOx) was used as the model biological recognition element. As a result of the enzymatic reaction between GOx and glucose, the glucose amount was det...
Synthesis and characterization of aluminum alloy 7075 reinforced with silicon carbide particulates
Kalkanlı, Ali (2008-01-01)
In this study 7075 matrix alloy is chosen and SiC particles having average particle size of 29 mu m was incorporated into the alloy at the liquid state before vertical pressure casting. Four different additions of SiCp were made and the weight fractions used are 10%, 15%, 20% and 30%. Composites were processed by vertical pressure/squeeze casting machine developed at Middle East Technical University (METU) under 80 MPa pressure. The mold is specially designed to produce specimens for tensile and three point...
Effect of post-processing heat treatment on the mechanical properties of inconel 718 fabricated by selective laser melting
Özer, Seren; Dericioğlu, Arcan Fehmi; Department of Metallurgical and Materials Engineering (2020)
In this study, effect of the building direction and post-processing heat treatments on the microstructure and high temperature mechanical properties of as-fabricatedInconel 718 alloys have been investigated. Inconel 718 samples were fabricated in two different building directions such that their longitudinalaxes wereeither parallel (horizontally built) or perpendicular (vertically built) to the building plate. During the selective laser melting (SLM)process, some undesired features can...
Citation Formats
M. N. Doğu, “Production of Ti-6Al-4V alloy by 3D electron beam melting technique and development of itspost treatments,” Thesis (M.S.) -- Graduate School of Natural and Applied Sciences. Metallurgical and Materials Engineering., Middle East Technical University, 2019.