scholarly journals Contactless temperature measurement in wire-based electron beam additive manufacturing Ti-6Al-4V

2021 ◽  
Author(s):  
F. Pixner ◽  
R. Buzolin ◽  
S. Schönfelder ◽  
D. Theuermann ◽  
F. Warchomicka ◽  
...  
Keyword(s):  
Electron Beam ◽  
Additive Manufacturing ◽  
Thermal Imaging ◽  
Temperature Profiles ◽  
Layer By Layer ◽  
Thermal Cycles ◽  
Cooling Rates ◽  
Geometric Boundary ◽  
Microstructural Characterisation ◽  
Local Misorientation

AbstractThe complex thermal cycles and temperature distributions observed in additive manufacturing (AM) are of particular interest as these define the microstructure and the associated properties of the part being built. Due to the intrinsic, layer-by-layer material stacking performed, contact methods to measure temperature are not suitable, and contactless methods need to be considered. Contactless infrared irradiation techniques were applied by carrying out thermal imaging and point measurement methods using pyrometers to determine the spatial and temporal temperature distribution in wire-based electron beam AM. Due to the vacuum, additional challenges such as element evaporation must be overcome and additional shielding measures were taken to avoid interference with the contactless techniques. The emissivities were calibrated by thermocouple readings and geometric boundary conditions. Thermal cycles and temperature profiles were recorded during deposition; the temperature gradients are described and the associated temperature transients are derived. In the temperature range of the α+β field, the cooling rates fall within the range of 180 to 350 °C/s, and the microstructural characterisation indicates an associated expected transformation of β→α'+α with corresponding cooling rates. Fine acicular α and α’ formed and local misorientation was observed within α as a result of the temperature gradient and the formation of the α’.

scholarly journals Effects of Positioning Conditions on Material Properties In Powder bed Fusion Additive Manufacturing

2021 ◽  
Author(s):  
Mevlüt Yunus Kayacan ◽  
Nihat Yılmaz
Keyword(s):  
Additive Manufacturing ◽  
Material Properties ◽  
Layer By Layer ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Cooling Rates ◽  
Powder Bed ◽  
Manufacturing Technologies ◽  
Average Size ◽  
Hardness Values

Abstract Among additive manufacturing technologies, Laser Powder Bed Fusion (L-PBF) is considered the most widespread layer-by-layer process. Although the L-PBF, which is also called as SLM method, has many advantages, several challenging problems must be overcome, including part positioning issues. In this study, the effect of part positioning on the microstructure of the part in the L-PBF method was investigated. Five Ti6Al4V samples were printed in different positions on the building platform and investigated with the aid of temperature, porosity, microstructure and hardness evaluations. In this study, martensitic needles were detected within the microstructure of Ti6Al4V samples. Furthermore, some twins were noticed on primary martensitic lines and the agglomeration of β precipitates was observed in vanadium rich areas. The positioning conditions of samples were revealed to have a strong effect on temperature gradients and on the average size of martensitic lines. Besides, different hardness values were attained depending on sample positioning conditions. As a major result, cooling rates were found related to positions of samples and the location of point on the samples. Higher cooling rates and repetitive cooling cycles resulted in microstructures becoming finer and harder.

Thermofluid Properties of Ti-6Al-4V Melt Pool in Powder-Bed Electron Beam Additive Manufacturing

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
M Shafiqur Rahman ◽  
Paul J. Schilling ◽  
Paul D. Herrington ◽  
Uttam K. Chakravarty
Keyword(s):  
Electron Beam ◽  
Additive Manufacturing ◽  
Heat Source ◽  
Thermal Behavior ◽  
Source Parameters ◽  
Three Dimensional ◽  
Full Density ◽  
Layer By Layer ◽  
Powder Bed ◽  
Melt Pool

Electron beam additive manufacturing (EBAM) is a powder-bed fusion additive manufacturing (AM) technology that can make full density metallic components using a layer-by-layer fabrication method. To build each layer, the EBAM process includes powder spreading, preheating, melting, and solidification. The quality of the build part, process reliability, and energy efficiency depends typically on the thermal behavior, material properties, and heat source parameters involved in the EBAM process. Therefore, characterizing those properties and understanding the correlations among the process parameters are essential to evaluate the performance of the EBAM process. In this study, a three-dimensional computational fluid dynamics (CFD) model with Ti-6Al-4V powder was developed incorporating the temperature-dependent thermal properties and a moving conical volumetric heat source with Gaussian distribution to conduct the simulations of the EBAM process. The melt pool dynamics and its thermal behavior were investigated numerically, and results for temperature profile, melt pool geometry, cooling rate and variation in density, thermal conductivity, specific heat capacity, and enthalpy were obtained for several sets of electron beam specifications. Validation of the model was performed by comparing the simulation results with the experimental results for the size of the melt pool.

Thermal Analysis of Electron Beam Additive Manufacturing Using Ti-6Al-4V Powder-Bed

2017 ◽  
Author(s):  
M. Shafiqur Rahman ◽  
Paul J. Schilling ◽  
Paul D. Herrington ◽  
Uttam K. Chakravarty
Keyword(s):  
Electron Beam ◽  
Additive Manufacturing ◽  
Three Dimensional ◽  
Vital Role ◽  
Full Density ◽  
Rate Variation ◽  
Layer By Layer ◽  
Powder Bed ◽  
Part Quality ◽  
Melt Pool

Electron Beam Additive Manufacturing (EBAM) is one of the emerging additive manufacturing (AM) technologies that is uniquely capable of making full density metallic components using layer-by-layer fabrication method. To build each layer, the process includes powder spreading, pre-heating, melting, and solidification. The thermal and material properties involved in the EBAM process play a vital role to determine the part quality, reliability, and energy efficiency. Therefore, characterizing the properties and understanding the correlations among the process parameters are incumbent to evaluate the performance of the EBAM process. In this study, a three dimensional computational fluid dynamics (CFD) model with Ti-6Al-4V powder has been developed incorporating the temperature-dependent thermal properties and a moving conical volumetric heat source with Gaussian distribution to conduct the simulations of the EBAM process. The melt-pool dynamics and its thermal behavior have been investigated numerically using a CFD solver and results for temperature profile, cooling rate, variation in density, thermal conductivity, specific heat capacity, and enthalpy have been obtained for a particular set of electron beam specifications.

Review on electron beam based additive manufacturing

2019 ◽  
Vol 26 (3) ◽  
pp. 485-498 ◽  
Author(s):  
Seema Negi ◽  
Athul Arun Nambolan ◽  
Sajan Kapil ◽  
Prathamesh Shreekant Joshi ◽  
Manivannan R. ◽  
...  
Keyword(s):  
Electron Beam ◽  
Additive Manufacturing ◽  
Research And Development ◽  
Design Methodology ◽  
Scanning Speed ◽  
Working Environment ◽  
Current Status ◽  
Layer By Layer ◽  
Content Type ◽  
High Scanning Speed

Purpose Electron beam-based additive manufacturing (EBAM) is an emerging technology to produce metal parts layer-by-layer. The purpose of this paper is to systematically address the research and development carried out for this technology, up till now. Design/methodology/approach This paper identifies several aspects of research and development in EBAM. Findings Electron beam has several unique advantages such as high scanning speed, energy efficiency, versatility for several materials and better part integrity because of a vacuum working environment. Originality/value This paper provides information on different aspects of EBAM with the current status and future scope.

scholarly journals Nanostructuring of Nb-Si-Cr Alloys by Electron Beam Melting to Improve the Mechanical Properties and the Oxidation Behavior

2021 ◽  
Author(s):  
A. Förner ◽  
J. Vollhüter ◽  
D. Hausmann ◽  
C. Arnold ◽  
P. Felfer ◽  
...  
Keyword(s):  
Electron Beam ◽  
Additive Manufacturing ◽  
Electron Beam Melting ◽  
Room Temperature ◽  
Single Layer ◽  
Atom Probe ◽  
Cooling Rates ◽  
High Cooling Rates ◽  
Very High

AbstractMaterials processed by additive manufacturing often exhibit a very fine-scaled microstructures due to high cooling rates in the process. In this study, single-layer surface electron beam melting is used to create very high cooling rates similar to additive manufacturing processes to investigate the resulting microstructure. In the case of Nb-Si-Cr in-situ composites, a nano-scaled eutectic microstructure is beneficial for improving the mechanical and oxidational properties. Fast solidification results in the formation of supersaturated phases of Nbss and Cr2Nb with phase diameters down to 10 nm as well as in the stabilization of the metastable Nb9(Cr,Si)5 phase at room temperature. After processing with different solidification rates, the decomposition of the Nb9(Cr,Si)5 phase has been studied in detail with atom probe microscopy. The stabilization of mixed silicide phases by electron beam melting shows a new pathway for improving hardness and enhancing oxidation resistance of nanostructured eutectic in-situ composites, by which the inherent weaknesses of Nb-Si-Cr can be overcome without further alloying elements. Graphical Abstract

Thermal imaging for assessment of electron-beam freeform fabrication (EBF3) additive manufacturing deposits

2013 ◽  
Author(s):  
Joseph N. Zalameda ◽  
Eric R. Burke ◽  
Robert A. Hafley ◽  
Karen M. Taminger ◽  
Christopher S. Domack ◽  
...  
Keyword(s):  
Electron Beam ◽  
Additive Manufacturing ◽  
Thermal Imaging ◽  
Freeform Fabrication

scholarly journals Influence of Microstructure and Defects on Mechanical Properties of AISI H13 Manufactured by Electron Beam Powder Bed Fusion

2021 ◽  
Author(s):  
Moritz Kahlert ◽  
Florian Brenne ◽  
Malte Vollmer ◽  
Thomas Niendorf
Keyword(s):  
Mechanical Properties ◽  
Electron Beam ◽  
Additive Manufacturing ◽  
Internal Cooling ◽  
Layer By Layer ◽  
Powder Bed Fusion ◽  
Powder Bed ◽  
Cooling Channels ◽  
Fine Grained ◽  
Aisi H13

AbstractElectron beam powder bed fusion (E-PBF) is a well-known additive manufacturing process. Components are realized based on layer-by-layer melting of metal powder. Due to the high degree of design freedom, additive manufacturing came into focus of tooling industry, especially for tools with sophisticated internal cooling channels. The present work focuses on the relationships between processing, microstructure evolution, chemical composition and mechanical properties of a high alloyed tool steel AISI H13 (1.2344, X40CrMoV5-1) processed by E-PBF. The specimens are free of cracks, however, lack of fusion defects are found upon use of non-optimized parameters finally affecting the mechanical properties detrimentally. Specimens built based on suitable parameters show a relatively fine grained bainitic/martensitic microstructure, finally resulting in a high ultimate strength and an even slightly higher failure strain compared to conventionally processed and heat treated AISI H13.

A Procedure for Determining the Operating Modes of Electron Beam Wire Feed Layer-Wise Deposition for Additive Manufacturing

Vestnik MEI ◽  
2017 ◽  
pp. 8-14 ◽  
Author(s):  
Aleksandr V. Gudenko ◽  
◽  
Viktor К. Dragunov ◽  
Andrey Р. Sliva ◽  
◽  
...  
Keyword(s):  
Electron Beam ◽  
Additive Manufacturing ◽  
Operating Modes ◽  
Wire Feed

Control of humping phenomenon and analyzing mechanical properties of Al–Si wire-arc additive manufacturing fabricated samples using cold metal transfer process

2021 ◽  
pp. 095440622199840
Author(s):  
Yashwant Koli ◽  
N Yuvaraj ◽  
Aravindan Sivanandam ◽  
Vipin
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Heat Input ◽  
Large Scale ◽  
High Deposition Rate ◽  
Bead Geometry ◽  
Layer By Layer ◽  
Cold Metal Transfer ◽  
Geometrical Shapes ◽  
Wire Arc Additive Manufacturing

Nowadays, rapid prototyping is an emerging trend that is followed by industries and auto sector on a large scale which produces intricate geometrical shapes for industrial applications. The wire arc additive manufacturing (WAAM) technique produces large scale industrial products which having intricate geometrical shapes, which is fabricated by layer by layer metal deposition. In this paper, the CMT technique is used to fabricate single-walled WAAM samples. CMT has a high deposition rate, lower thermal heat input and high cladding efficiency characteristics. Humping is a common defect encountered in the WAAM method which not only deteriorates the bead geometry/weld aesthetics but also limits the positional capability in the process. Humping defect also plays a vital role in the reduction of hardness and tensile strength of the fabricated WAAM sample. The humping defect can be controlled by using low heat input parameters which ultimately improves the mechanical properties of WAAM samples. Two types of path planning directions namely uni-directional and bi-directional are adopted in this paper. Results show that the optimum WAAM sample can be achieved by adopting a bi-directional strategy and operating with lower heat input process parameters. This avoids both material wastage and humping defect of the fabricated samples.

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