Optimization of the mechanical properties of Ti-6Al-4V alloy produced by three dimensional additive manufacturing using termochemical processes

Bilgin, Güney Mert
Selective laser melting (SLM) is an additive manufacturing (AM) technology used for aerospace and biomedical Ti-6Al-4V alloys to produce parts with complex geometry at one step with reduced production time, scrap and cost. However, parts produced by SLM are lack of ductility due to microstructures similar to those cast products and residual stresses generated during laser processing. In this study, Ti6Al-4V alloys produced by SLM were treated by thermo-hydrogen process (THP) to increase ductility and to refine the microstructure without changing the parts‟ final geometry as opposed to thermo-mechanical processes. It has been observed that conventional 4-step THP decrease alloy‟s mechanical properties despite refined microstructure because of grain boundary α-phase formation during β-solutionizing and eutectoid decomposition steps. Additionally, excessive growth of β-grains occurred during β-solutionizing was another drawback of the 4-step process. On the other hand, modified 2-step THP, which was conducted below α/β transition temperature, was found to increase the alloy‟s ductility without degrading its strength. Although similar microstructures were developed in samples treated by 2- and 4-step THP, grain growth and grain boundary α- phase formation was not encountered in samples treated by 2-step THP. Even though hydrogen absorption of the alloy has not been changed considerably, initial microstructure of the alloy was found to be effective on final properties. THP transformed α'-martensite to fine α and β phases by significant increase in ductility, while it did not alter the type of phases and ductility too much in samples containing lamellar α+β microstructure; however, a discontinuous morphology was obtained. 


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...
Simulator of an additive and subtractive type of hybrid manufacturing system
Dilberoğlu, Mecid Uğur; Yaman, Ulaş; Dölen, Melik (2019-06-24)
Additive Manufacturing (AM) facilitates the production of intricate objects despite its weakness in attainable part quality and fabrication speed compared to the conventional manufacturing methods. To alleviate the problems arising as a natural outcome of AM methods, hybrid technologies become viable options by employing concurrent manufacturing procedures, e.g. synergetic additive and subtractive manufacturing (SM) actions. Hybrid workstations have recently opened up new dimensions to 3D-printing industry,...
Manufacturing of Functionally Graded Porous Products by Selective Laser Sintering
Erdal Erdoğmuş, Merve; Dağ, Serkan (2008-09-25)
Selective laser sintering (SLS) is a rapid prototyping technique which is used to manufacture plastic and metal models. The porosity of the final product obtained by SLS can be controlled by changing the energy density level used during the manufacturing process. The energy density level is itself dependent upon manufacturing parameters such as laser power, hatching distance and scanning speed. Through mechanical characterization techniques, it is possible to quantitatively relate the energy density levels ...
Extracting auxetic patterns from meshes for 3d printing
Mert, Mehmet Levend; Sahillioğlu, Yusuf; Yaman, Ulaş; Department of Computer Engineering (2018)
3D printing is a manufacturing process which generates a physical, three-dimensional object from a digital design. In our day, there exist lots of devices, called 3D printers, having different working principles and using various materials for this manufacturing process. A model designed digitally can be transformed into a three-dimensional object in the real world by 3D printers. The elasticity of objects created by 3D printers depends on the materials used during manufacturing and the digital designs. If ...
Optimization of Pyrolysis and Liquid Silicon Infiltration Parameters for the Processing of C C SiC Composites
Tulbez, Simge; Esen, Ziya; Dericioğlu, Arcan Fehmi (2016-11-25)
The aim of the current study is to investigate the production and characterization of Carbon Fiber Reinforced Silicon Carbide (C/C-SiC) Matrix Composites. Liquid silicon infiltration (LSI) method was utilized to produce the C/C-SiC composites. Processing of these composites via LSI process contains there main steps: Carbon Fiber Reinforced Polymer (CFRP) composite production, pyrolysis and liquid silicon infiltration. Each production step has an important effect on the efficiency of the LSI process, therefo...
Citation Formats
G. M. Bilgin, “Optimization of the mechanical properties of Ti-6Al-4V alloy produced by three dimensional additive manufacturing using termochemical processes,” M.S. - Master of Science, Middle East Technical University, 2017.