scholarly journals Plasma Multiwire Technology with Alternating Wire Feed for Tailor-Made Material Properties in Wire and Arc Additive Manufacturing

Metals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 745 ◽  
Author(s):  
Uwe Reisgen ◽  
Rahul Sharma ◽  
Lukas Oster
Keyword(s):  
Additive Manufacturing ◽  
Chemical Composition ◽  
Material Properties ◽  
Large Scale ◽  
Welding Process ◽  
Chemical Compositions ◽  
The Wire ◽  
Graded Structures ◽  
Wire Feed

Wire and arc additive manufacturing (WAAM) is one of the most promising technologies for large-scale 3D printing of metal parts. Besides the high deposition rates, one of the advantages of WAAM is the possibility of using in situ alloying to modify the chemical composition and therefore the material properties of the fabricated workpiece. This can be achieved by feeding multiple wires of different chemical compositions into the molten pool of the welding process and generating a new alloy during the manufacturing process itself. At present, the chemical composition is changed stepwise by keeping the wire feed speeds per layer constant. This article describes the possibilities of generating chemically graded structures by constantly alternating the wire feed speeds of a multiwire WAAM process. This enables the chemical composition to be smoothly changed during the printing process, and generating structures with highly complex material properties. Several material combinations for different possible applications were successfully tested. Furthermore, grading strategies to avoid negative influences of low-ductility intermetallic phases were examined. The results show that low-ductility phases may even have a beneficial influence on the fracture behavior if they are combined with ductile phases. Moreover, prospective possible applications are discussed.

scholarly journals In situ alloying of aluminium-based alloys by (multi-)wire-arc additive manufacturing

2020 ◽  
Vol 326 ◽  
pp. 01003
Author(s):  
Thomas Klein ◽  
Alois Birgmann ◽  
Martin Schnall
Keyword(s):  
Additive Manufacturing ◽  
Large Scale ◽  
Welding Process ◽  
Chemical Compositions ◽  
Present Contribution ◽  
Cold Metal Transfer ◽  
Chemical Homogeneity ◽  
Welding Equipment ◽  
Wire Arc Additive Manufacturing

Wire-arc additive manufacturing (WAAM) has received considerable attention in the past years due to advantages in terms of deposition rate, design freedom, buy-to-fly ratio and economic factors. This process can generally be conducted using conventional or near-conventional welding equipment to fabricate intricate but relatively large-scale structures. The present contribution explores options to utilize this novel process not only for manufacturing of particular aluminium structures, but to create the actual alloy composition during processing. Thereby, the possibilities of dual-wire techniques based on cold metal transfer (CMT) to create alloys in the welding process in situ is investigated. For this purpose, a modified CMT twin welding system is used with standard wires differing significantly in their alloying content. The characterization of the chemical compositions at different specimen positions suggests good chemical homogeneity after initial process optimization steps. The microstructural homogeneity is analysed by means of optical light microscopy and scanning electron microscopy. Quantified phase fractions underpin non-equilibrium solidification conditions, when compared to theoretical equilibrium predictions. The assessment of the performed analyses suggests that dual-wire processes are powerful in terms of enhancing achievable depositions rates as well as enabling in situ alloying. This approach might be expandable to multi-wire-based techniques.

scholarly journals Relationship between the Optical Properties and Chemical Composition of Urban Aerosol Particles in Lithuania

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Julija Pauraite ◽  
Kristina Plauškaitė ◽  
Vadimas Dudoitis ◽  
Vidmantas Ulevicius
Keyword(s):  
Optical Properties ◽  
Chemical Composition ◽  
Organic Aerosol ◽  
Single Scattering ◽  
Chemical Compositions ◽  
Spectra Analysis ◽  
Average Value ◽  
Aerosol Mass ◽  
In Situ Investigation

In situ investigation results of aerosol optical properties (absorption and scattering) and chemical composition at an urban background site in Lithuania (Vilnius) are presented. Investigation was performed in May-June 2017 using an aerosol chemical speciation monitor (ACSM), a 7-wavelength Aethalometer and a 3-wavelength integrating Nephelometer. A positive matrix factorisation (PMF) was used for the organic aerosol mass spectra analysis to characterise the sources of ambient organic aerosol (OA). Five OA factors were identified: hydrocarbon-like OA (HOA), biomass-burning OA (BBOA), more and less oxygenated OA (LVOOA and SVOOA, respectively), and local hydrocarbon-like OA (LOA). The average absorption (at 470 nm) and scattering (at 450 nm) coefficients during the entire measurement campaign were 16.59 Mm−1 (standard deviation (SD) = 17.23 Mm−1) and 29.83 Mm−1 (SD = 20.45 Mm−1), respectively. Furthermore, the absorption and scattering Angström exponents (AAE and SAE, respectively) and single-scattering albedo (SSA) were calculated. The average AAE value at 470/660 nm was 0.97 (SD = 0.16) indicating traffic-related black carbon (BCtr) dominance. The average value of SAE (at 450/700 nm) was 1.93 (SD = 0.32) and could be determined by the submicron particle (PM1) dominance versus the supermicron ones (PM > 1 µm). The average value of SSA was 0.62 (SD = 0.13). Several aerosol types showed specific segregation in the SAE versus SSA plot, which underlines different optical properties due to various chemical compositions.

scholarly journals Material Extrusion Additive Manufacturing of Wood and Lignocellulosic Filled Composites

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2115
Author(s):  
Meghan E. Lamm ◽  
Lu Wang ◽  
Vidya Kishore ◽  
Halil Tekinalp ◽  
Vlastimil Kunc ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
3D Printing ◽  
Present State ◽  
Material Properties ◽  
Large Scale ◽  
State Of The Art ◽  
Material Extrusion ◽  
Functional Additives ◽  
Natural Filler ◽  
Natural Fillers

Wood and lignocellulosic-based material components are explored in this review as functional additives and reinforcements in composites for extrusion-based additive manufacturing (AM) or 3D printing. The motivation for using these sustainable alternatives in 3D printing includes enhancing material properties of the resulting printed parts, while providing a green alternative to carbon or glass filled polymer matrices, all at reduced material costs. Previous review articles on this topic have focused only on introducing the use of natural fillers with material extrusion AM and discussion of their subsequent material properties. This review not only discusses the present state of materials extrusion AM using natural filler-based composites but will also fill in the knowledge gap regarding state-of-the-art applications of these materials. Emphasis will also be placed on addressing the challenges associated with 3D printing using these materials, including use with large-scale manufacturing, while providing insight to overcome these issues in the future.

scholarly journals Investigation of penetrator defect formation during high frequency induction welding in pipeline steels

2021 ◽  
Vol 349 ◽  
pp. 04002
Author(s):  
Christos Sofras ◽  
Marianthi Bouzouni ◽  
Nikolaos Voudouris ◽  
Spyros Papaefthymiou
Keyword(s):  
Chemical Composition ◽  
High Frequency ◽  
Defect Formation ◽  
Welding Process ◽  
High Strength ◽  
Chemical Compositions ◽  
Oxide Formation ◽  
Pipeline Steels ◽  
The Impact ◽  
High Frequency Induction

The aim of this study is to investigate the formation of oxide defects known as penetrators during high frequency induction welding process of high strength low alloy pipeline steels and to correlate their formation with the steel chemical composition. Penetrators formed during the welding process can be detrimental for the impact properties of the weld seam. For this purpose, three different samples, with different chemical compositions, were intentionally produced with penetrator-type oxides and investigated. In order to characterize the oxide defect and correlate their formation with the chemical composition of the steel, optical microscopy and scanning electron microscopy paired with energy dispersive spectroscopy were employed. In addition, thermodynamic calculations were performed in order to examine whether the chemical composition of pipeline steels is prone to oxide formation. The results showed that oxides with pancake type morphology were found alongside the fusion zone of the samples. They mainly consisted of manganese and silicon. First findings on the the Mn/Si ratio showed that the lower ratio is less susceptible to oxide formation.

scholarly journals In Situ and Ex Situ Characterization of the Microstructure Formation in Ni-Cr-Si Alloys during Rapid Solidification—Toward Alloy Design for Laser Additive Manufacturing

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2192
Author(s):  
Xiaoshuang Li ◽  
Kai Zweiacker ◽  
Daniel Grolimund ◽  
Dario Ferreira Sanchez ◽  
Adriaan B. Spierings ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Chemical Composition ◽  
Laser Beam ◽  
Rapid Solidification ◽  
Liquid Droplet ◽  
Lamellar Microstructure ◽  
Ex Situ ◽  
X Ray Diffraction ◽  
X Ray

Laser beam-based deposition methods such as laser cladding or additive manufacturing of metals promises improved properties, performance, and reliability of the materials and therefore rely heavily on understanding the relationship between chemical composition, rapid solidification processing conditions, and resulting microstructural features. In this work, the phase formation of four Ni-Cr-Si alloys was studied as a function of cooling rate and chemical composition using a liquid droplet rapid solidification technique. Post mortem x-ray diffraction, scanning electron microscopy, and in situ synchrotron microbeam X-ray diffraction shows the present and evolution of the rapidly solidified microstructures. Furthermore, the obtained results were compared to standard laser deposition tests. In situ microbeam diffraction revealed that due to rapid cooling and an increasing amount of Cr and Si, metastable high-temperature silicides remain in the final microstructure. Due to more sluggish interface kinetics of intermetallic compounds than that of disorder solid solution, an anomalous eutectic structure becomes dominant over the regular lamellar microstructure at high cooling rates. The rapid solidification experiments produced a microstructure similar to the one generated in laser coating thus confirming that this rapid solidification test allows a rapid pre-screening of alloys suitable for laser beam-based processing techniques.

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