Comparison of the electrochemical machinability of electron beam melted and casted gamma titanium aluminide TNB-V5

2017 ◽  
Vol 232 (4) ◽  
pp. 586-592 ◽  
Author(s):  
Fritz Klocke ◽  
Tim Herrig ◽  
Markus Zeis ◽  
Andreas Klink
Keyword(s):  
Surface Roughness ◽  
Electron Beam ◽  
Current Density ◽  
Titanium Aluminide ◽  
Titanium Aluminides ◽  
Electrochemical Machining ◽  
Dissolution Behavior ◽  
Removal Rates ◽  
Gamma Titanium Aluminide ◽  
Gamma Titanium

Additive manufacturing technologies are becoming more and more important for the implementation of efficient process chains. Due to the possibility of a near net shape, manufacturing time for finish-machining can significantly be reduced. Especially for conventionally hard to machine materials like gamma titanium aluminides (γ-TiAl), this manufacturing process is very attractive. Nevertheless, for most applications, a rework of these generative components is necessary. Independently of the mechanical material properties, electrochemical machining is one promising technology of machining these materials. Major advantages of electrochemical machining are its process-specific characteristics of high material removal rates in combination with almost no tool wear. But electrochemical machining results are highly dependent on the microstructure of the material regarding the surface roughness. Therefore, this article deals with research on electrochemical machining of electron beam melted γ-TiAl TNB-V5 compared to a casted form of this alloy. The difference between the specific removal rates as a function of current density is investigated using electrolytes based on sodium nitrate and sodium chloride. Moreover, the dissolving behavior of the electron beam melted and casted structure is analyzed by potentiostatic polarization curves. The surface roughness is heavily dependent on a homogeneous dissolution behavior of the microstructure. Thus, the mean roughness as a function of current density is investigated as well as rim zone analyses of the different structures.

Effect of melt parameters on density and surface roughness in electron beam melting of gamma titanium aluminide alloy

2017 ◽  
Vol 23 (3) ◽  
pp. 474-485 ◽  
Author(s):  
Ashfaq Mohammad ◽  
Abdurahman Mushabab Al-Ahmari ◽  
Abdullah AlFaify ◽  
Muneer Khan Mohammed
Keyword(s):  
Surface Roughness ◽  
Electron Beam ◽  
Additive Manufacturing ◽  
Titanium Aluminide ◽  
Electron Beam Melting ◽  
Tial Alloy ◽  
Gamma Titanium Aluminide ◽  
Content Type ◽  
Gamma Titanium ◽  
New Material

Purpose Electron beam melting (EBM) is one of the potential additive manufacturing technologies to fabricate aero-engine components from gamma titanium aluminide (γ-TiAl) alloys. When a new material system has to be taken in to the fold of EBM, which is a highly complex process, it is essential to understand the effect of process parameters on the final quality of parts. This paper aims to understand the effect of melting parameters on top surface quality and density of EBM manufactured parts. This investigation would accelerate EBM process development for newer alloys. Design/methodology/approach Central composite design approach was used to design the experiments. In total, 50 specimens were built in EBM with different melt theme settings. The parameters varied were surface temperature, beam current, beam focus offset, line offset and beam speed. Density and surface roughness were selected as responses in the qualifying step of the parts. After identifying the parameters which were statistically significant, possible reasons were analyzed from the perspective of the EBM process. Findings The internal porosity and surface roughness were correlated to the process settings. Important ones among the parameters are beam focus offset, line offset and beam speed. By jointly deciding the total amount of energy input for each layer, these three parameters played a critical role in internal flaw generation and surface evolution. Research limitations/implications The range selected for each parameter is applicable, in particular, to γ-TiAl alloy. For any other alloy, the settings range has to be suitably adapted depending on physical properties such as melting point, thermal conductivity and thermal expansion co-efficient. Practical implications This paper demonstrates how melt theme parameters have to be understood in the EBM process. By adopting a similar strategy, an optimum window of settings that give best consolidation of powder and better surface characteristics can be identified whenever a new material is being investigated for EBM. This work gives researchers insights into EBM process and speeds up EBM adoption by aerospace industry to produce critical engine parts from γ-TiAl alloy. Originality/value This work is one of the first attempts to systematically carry out a number of experiments and to evaluate the effect of melt parameters for producing γ-TiAl parts by the EBM process. Its conclusions would be of value to additive manufacturing researchers working on γ-TiAl by EBM process.

The Dependence of Tensile Ductility on Investment Casting Parameters in Gamma Titanium Aluminides

1998 ◽  
Vol 552 ◽  
Author(s):  
R. Raban ◽  
L. L. ◽  
T. M.
Keyword(s):  
Titanium Aluminide ◽  
Titanium Aluminides ◽  
Tensile Ductility ◽  
Gamma Titanium Aluminide ◽  
Cooling Rates ◽  
Gamma Titanium ◽  
Investment Cast ◽  
Thermal Data ◽  
Titanium Aluminide Alloys ◽  
Simulation Package

ABSTRACTPlates of three gamma titanium aluminide alloys have been investment cast with a wide variety of casting conditions designed to influence cooling rates. These alloys include Ti-48Al-2Cr-2Nb, Ti- 47Al-2Cr-2Nb+0.5at%B and Ti-45Al-2Cr-2Nb+0.9at%B. Cooling rates have been estimated with the use of thermal data from casting experiments, along with the UES ProCAST simulation package. Variations in cooling rate significantly influenced the microstructure and tensile properties of all three alloys.

Studies on Ductile Damage and Flow Instabilities during Hot Deformation of a Multiphase γ-TiAl Alloy

2014 ◽  
Vol 611-612 ◽  
pp. 99-105 ◽  
Author(s):  
Dilek Halici ◽  
Hassan Adrian Zamani ◽  
Daniel Prodinger ◽  
Cecilia Poletti ◽  
Daniel Huber ◽  
...  
Keyword(s):  
Hot Deformation ◽  
Titanium Aluminide ◽  
Titanium Aluminides ◽  
Turbine Blades ◽  
Shear Bands ◽  
Flow Instabilities ◽  
Ductile Damage ◽  
Gamma Titanium Aluminide ◽  
Gamma Titanium ◽  
Damage Models

Gamma titanium aluminides are promising alloys for low-pressure turbine blades. A significant disadvantage of such intermetallic alloys is failure induced during forming processes due to ductile damage and flow instabilities. Previous investigations on a gamma titanium aluminide alloy (TNM), have shown ductile damage due to tensile stress components and instabilities such as shear bands, pores and micro-cracks at low temperatures and high strain rates. The main part of the current work is to delineate damage and unstable regions in the low temperature region. Hot deformation experiments are conducted on a Gleeble®3800 thermomechanical treatment simulator to obtain flow curves to be implemented in a finite element method (FEM) code. Instabilities in the material are described by existing instability criteria as proposed by Semiatin and Jonas and implemented into FEM code DEFORMTM 2D. Predictions of ductile damage models and the instability parameter are validated through detailed microstructural studies of deformed specimens analysed by light optical- and scanning electron microscopy.

scholarly journals Microstructures for Two-Phase Gamma Titanium Aluminide Fabricated by Electron Beam Melting

2012 ◽  
Vol 1 (1) ◽  
pp. 14-27 ◽  
Author(s):  
Jennifer Hernandez ◽  
Lawrence E. Murr ◽  
Sara M. Gaytan ◽  
Edwin Martinez ◽  
Frank Medina ◽  
...  
Keyword(s):  
Electron Beam ◽  
Titanium Aluminide ◽  
Electron Beam Melting ◽  
Two Phase ◽  
Gamma Titanium Aluminide ◽  
Gamma Titanium

Microstructure of Ti-45Al-5Nb after Cathodic Charging

2010 ◽  
Vol 95 ◽  
pp. 87-90
Author(s):  
E. Barel ◽  
Guy Ben-Hamu ◽  
D. Eliezer
Keyword(s):  
Current Density ◽  
Titanium Aluminide ◽  
Electronic Microscopy ◽  
Gamma Titanium Aluminide ◽  
Gamma Titanium ◽  
Charging Mode ◽  
A Current ◽  
Cathodic Charging

Gamma titanium aluminide material, cast Ti–45Al–5Nb (at.%), was electrochemically precharged with hydrogen in the cathodic charging mode at a current density of 50 mA/cm2 for times ranging from 6 to 48 h. XRD and microstructure investigations by means of electronic microscopy were used for analyzed the influence of hydrogen on the microstructure.

Development of Ceramic Moulds with Zirconia Primary Coat for Investment Casting of Gamma Titanium Aluminide Based Alloys

2011 ◽  
Vol 55-57 ◽  
pp. 881-885
Author(s):  
Yan Fei Chen ◽  
Shu Long Xiao ◽  
Jing Tian ◽  
Li Juan Xu ◽  
Yu Yong Chen
Keyword(s):  
Surface Roughness ◽  
Fracture Strength ◽  
Investment Casting ◽  
Titanium Aluminide ◽  
Average Surface Roughness ◽  
Gamma Titanium Aluminide ◽  
Tial Alloys ◽  
Average Surface ◽  
Gamma Titanium ◽  
Technology Demonstration

The fabrication of ceramic moulds with zirconia primary coat for investment casting of gamma titanium aluminide based alloys (hereafter called TiAl alloys) was described in this study. The microstructures and fracture strength of ceramic moulds were characterized. The fracture strength and surface roughness of the ceramic moulds with zirconia primary coat were sufficient for the TiAl investment casting. TiAl blades were used for the technology demonstration in producing TiAl components. TiAl castings produced by the ceramic moulds exhibited an average surface roughness (Ra ) of 6 μm.

Microstructural Properties of Gamma Titanium Aluminide Manufactured by Electron Beam Melting

2011 ◽  
pp. 455-462 ◽  
Author(s):  
Sanna Fager Franzén ◽  
Joakim Karlsson ◽  
Ryan Dehoff ◽  
Ulf Ackelid ◽  
Orlando Rios ◽  
...  
Keyword(s):  
Electron Beam ◽  
Titanium Aluminide ◽  
Electron Beam Melting ◽  
Microstructural Properties ◽  
Gamma Titanium Aluminide ◽  
Gamma Titanium

Modelling of the Ductile Damage Behaviour of a Beta Solidifying Gamma Titanium Aluminide Alloy during Hot-Working

2014 ◽  
Vol 783-786 ◽  
pp. 556-561 ◽  
Author(s):  
Dilek Halici ◽  
Daniel Prodinger ◽  
Cecilia Poletti ◽  
Daniel Huber ◽  
Martin Stockinger ◽  
...  
Keyword(s):  
Titanium Aluminide ◽  
Titanium Aluminides ◽  
Hydrostatic Stress ◽  
Effective Strain ◽  
Maximum Principal Stress ◽  
Ductile Damage ◽  
Hot Workability ◽  
Gamma Titanium Aluminide ◽  
Gamma Titanium ◽  
Damage Criteria

Gamma titanium aluminides are innovative materials for high temperature and light weight applications [1]. On the other hand, their hot workability can be limited by failure during hot deformation processes. The prediction of ductile damage in metallic materials can be performed by macromechanical ductile damage criteria [2-4]. If the calculated damage D parameter exceeds a critical value Dc, the material fails. Some macromechanical ductile damage criteria are shown in Table 1, with σ as effective stress, ε as effective strain, σmax as maximum principal stress, σm as hydrostatic stress (mean stress) and εf as equivalent fracture strain. The damage responds to strain localization and thus, to multiaxial stress concentration that increases fracture probability.

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