Ultrasonic Nondestructive Testing for In-Line Monitoring of Wire-Arc Additive Manufacturing (WAAM)

2020 ◽  
Author(s):  
Md Shahjahan Hossain ◽  
Hossein Taheri ◽  
Niraj Pudasaini ◽  
Alexander Reichenbach ◽  
Bishal Silwal
Keyword(s):  
Quality Assurance ◽  
Additive Manufacturing ◽  
Nondestructive Testing ◽  
Large Scale ◽  
Gas Flow ◽  
Complex Structure ◽  
Process Condition ◽  
Process Conditions ◽  
Ultrasonic Signals ◽  
Wire Arc Additive Manufacturing

Abstract The applications for metal additive manufacturing (AM) are expanding. Powder-bed, powder-fed, and wire-fed AM are the different kinds of AM technologies based on the feeding material. Wire-Arc AM (WAAM) is a wire-fed technique that has the potential to fabricate large-scale three-dimensional objects. In WAAM, a metallic wire is continuously fed to the deposition location and is melted by an arc-welding power source. As the applications for WAAM expands, the quality assurance of the parts becomes a major concern. Nondestructive testing (NDT) of AM parts is necessary for quality assurance and inspection of these materials. The conventional method of inspection is to perform testing on the finished parts. There are several limitations encountered when using conventional methods of NDT for as-built AM parts due to surface conditions and complex structure. In-situ process monitoring based on the ultrasound technology is proposed for WAAM material inspection during the manufacturing process. Ultrasonic inline monitoring techniques have the advantages of providing valuable information about the process and parts quality. Ultrasonic technique was used to detect the process condition deviations from the normal. A fixture developed by the authors holds an ultrasonic sensor under the build platform and aligned with the center of the base plate. Ultrasonic signals were measured for different process conditions by varying the current and gas flow rate. Features (indicators) from the radio frequency (RF) signal were used to evaluate the difference in signal clusters to identify and classify different build conditions. Results show that the indicator values of the ultrasonic signals in the region of interest (ROI) changes with different process conditions and can be used to classify them.

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.

scholarly journals Compression Behaviour of Wire + Arc Additive Manufactured Structures

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 877
Author(s):  
Masoud Abbaszadeh ◽  
Volker Ventzke ◽  
Leonor Neto ◽  
Stefan Riekehr ◽  
Filomeno Martina ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Large Scale ◽  
Grain Morphology ◽  
Electron Back Scatter Diffraction ◽  
Compression Tests ◽  
Homogeneous Microstructure ◽  
Compression Loading ◽  
Anisotropic Behaviour ◽  
Mechanical And Microstructural Properties ◽  
Wire Arc Additive Manufacturing

Increasing demand for producing large-scale metal components via additive manufacturing requires relatively high building rate processes, such as wire + arc additive manufacturing (WAAM). For the industrial implementation of this technology, a throughout understanding of material behaviour is needed. In the present work, structures of Ti-6Al-4V, AA2319 and S355JR steel fabricated by means of WAAM were investigated and compared with respect to their mechanical and microstructural properties, in particular under compression loading. The microstructure of WAAM specimens is assessed by scanning electron microscopy, electron back-scatter diffraction, and optical microscopy. In Ti-6Al-4V, the results show that the presence of the basal and prismatic crystal planes in normal direction lead to an anisotropic behaviour under compression. Although AA2319 shows initially an isotropic plastic behaviour, the directional porosity distribution leads to an anisotropic behaviour at final stages of the compression tests before failure. In S355JR steel, isotropic mechanical behaviour is observed due to the presence of a relatively homogeneous microstructure. Microhardness is related to grain morphology variations, where higher hardness near the inter-layer grain boundaries for Ti-6Al-4V and AA2319 as well as within the refined regions in S355JR steel is observed. In summary, this study analyzes and compares the behaviour of three different materials fabricated by WAAM under compression loading, an important loading condition in mechanical post-processing techniques of WAAM structures, such as rolling. In this regard, the data can also be utilized for future modelling activities in this direction.

scholarly journals Wire Arc Additive Manufacturing (WAAM) of Aluminum Alloy AlMg5Mn with Energy-Reduced Gas Metal Arc Welding (GMAW)

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2671 ◽  
Author(s):  
Maximilian Gierth ◽  
Philipp Henckell ◽  
Yarop Ali ◽  
Jonas Scholl ◽  
Jean Pierre Bergmann
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Arc Welding ◽  
Energy Input ◽  
Large Scale ◽  
Unit Length ◽  
Gas Metal Arc Welding ◽  
Cold Metal Transfer ◽  
Metal Arc Welding ◽  
Wire Arc Additive Manufacturing

Large-scale aluminum parts are used in aerospace and automotive industries, due to excellent strength, light weight, and the good corrosion resistance of the material. Additive manufacturing processes enable both cost and time savings in the context of component manufacturing. Thereby, wire arc additive manufacturing (WAAM) is particularly suitable for the production of large volume parts due to deposition rates in the range of kilograms per hour. Challenges during the manufacturing process of aluminum alloys, such as porosity or poor mechanical properties, can be overcome by using arc technologies with adaptable energy input. In this study, WAAM of AlMg5Mn alloy was systematically investigated by using the gas metal arc welding (GMAW) process. Herein, correlations between the energy input and the resulting temperature–time-regimes show the effect on resulting microstructure, weld seam irregularities and the mechanical properties of additively manufactured aluminum parts. Therefore, multilayer walls were built layer wise using the cold metal transfer (CMT) process including conventional CMT, CMT advanced and CMT pulse advanced arc modes. These processing strategies were analyzed by means of energy input, whereby the geometrical features of the layers could be controlled as well as the porosity to area portion to below 1% in the WAAM parts. Furthermore, the investigations show the that mechanical properties like tensile strength and material hardness can be adapted throughout the energy input per unit length significantly.

scholarly journals Finite Element Modeling and Validation of Metal Deposition in Wire Arc Additive Manufacturing

2021 ◽  
pp. 61-66
Author(s):  
Akram Chergui ◽  
Nicolas Beraud ◽  
Frédéric Vignat ◽  
François Villeneuve
Keyword(s):  
Finite Element ◽  
Additive Manufacturing ◽  
Large Scale ◽  
Low Cost ◽  
Source Model ◽  
Metal Deposition ◽  
High Deposition Rate ◽  
Element Technique ◽  
Metallic Parts ◽  
Wire Arc Additive Manufacturing

AbstractWire arc additive manufacturing allows the production of metallic parts by depositing beads of weld metal using arc-welding technologies. This low-cost additive manufacturing technology has the ability to manufacture large-scale parts at a high deposition rate. However, the quality of the obtained parts is greatly affected by the various thermal phenomena present during the manufacturing process. Numerical simulation remains an effective tool for studying such phenomena. In this work, a new finite element technique is proposed in order to model metal deposition in WAAM process. This technique allows to gradually construct the mesh representing the deposited regions along the deposition path. The heat source model proposed by Goldak is adapted and combined with the proposed metal deposition technique taking into account the energy distribution between filler material and the molten pool. The effectiveness of the proposed method is validated by series of experiments, of which an example is detailed in this paper.

scholarly journals Vision-Based Melt Pool Monitoring for Wire-Arc Additive Manufacturing Using Deep Learning Method

2021 ◽  
Author(s):  
Chunyang Xia ◽  
Zengxi Pan ◽  
Yuxing Li ◽  
Huijun Li
Keyword(s):  
Deep Learning ◽  
Additive Manufacturing ◽  
Large Scale ◽  
Deposition Process ◽  
Utilization Rate ◽  
High Deposition Rate ◽  
Promising Alternative ◽  
Visual Monitoring ◽  
Melt Pool ◽  
Wire Arc Additive Manufacturing

Abstract Wire-arc additive manufacturing (WAAM) technology has been widely recognized as a promising alternative for fabricating large-scale components, due to its advantages of high deposition rate and high material utilization rate. However, some anomalies may occur during the deposition process, such as humping, spattering, and robot suspend. this study proposed to apply Deep Learning in the visual monitoring to diagnose different anomalies during WAAM process. The melt pool images of different anomalies were collected for training and validation by a visual monitoring system. The classification performance of several representative CNN architectures, including ResNet, EfficientNet, VGG-16 and GoogLeNet, were investigated and compared. The classification accuracy of 97.62%, 97.45%, 97.15% and 97.25% was achieved by each model. The results proved that the CNN models are effective in classifying different types of melt pool images of WAAM. Our study is applicable beyond WAAM and should benefit other additive manufacturing or arc welding techniques.

scholarly journals Influence of wire arc additive manufacturing of Ti-6Al-4V on microstructure and mechanical properties for potential large-scale aviation parts

2020 ◽  
Vol 321 ◽  
pp. 03037
Author(s):  
D. Elitzer ◽  
H.W. Höppel ◽  
M. Göken ◽  
D. Baier ◽  
C. Fuchs ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Additive Manufacturing ◽  
Mechanical Strength ◽  
Large Scale ◽  
Solution Treatment ◽  
Compression Tests ◽  
Process Gas ◽  
Relationship Of ◽  
Wire Arc Additive Manufacturing

As one of the most common Titanium alloys, Ti-6Al-4V faces new challenges concerning the ecological footprint. Due to the current processes, a high metal chip pollution leads to a Buy-to-Fly of 25:1. In this study the parameter / microstructure relationship of Ti-64 on the mechanical properties are discussed. Wire Arc Additive Manufacturing (WAAM) was applied to build samples for microstructural analyses and compression tests. A stress relief (SR) and a solution treatment and annealing (STA) was performed. It was found that SR had no influence on multi-layered samples due to intrinsic heat-treatment. A STA heat-treatment led to a reduction in the mechanical strength. Helium as process gas resulted in an increased mechanical strength due to higher heat capacity compared to argon.

scholarly journals The Effect of Laser Remelting on the Microstructure and Mechanical Properties of the Bonding Interface in a Hybrid Metal Additive Manufacturing Process

2021 ◽  
Author(s):  
Fei Xue ◽  
Xin Cui ◽  
Longfei Zheng ◽  
Mian Li ◽  
Xuewei Fang
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Substrate Surface ◽  
Complex Structure ◽  
Bonding Interface ◽  
Machining Process ◽  
Laser Remelting ◽  
Metal Additive Manufacturing ◽  
Wire Arc Additive Manufacturing ◽  
Metal Additive

Abstract In order to realize both high-efficient forming with the wire arc additive manufacturing (WAAM) and precise forming with the laser metal deposition (LMD) for some complex-structure and high-precision parts, a hybrid metal additive manufacturing method is proposed. The part is decomposed into sub volumes, then the sub volumes with relatively simple-structure features are formed through WAAM as a substrate, and the other sub volumes with more complex-structure or small-sized features are formed through LMD on the former substrate. However, the mechanical properties of the bonding interface would be reduced, if the later sub volumes are directly deposited by LMD on the rough WAAM substrate surface. In order to avoid unnecessary machining process between WAAM and LMD for high efficiency, and ensure the mechanical properties of WAAM-LMD bonding interface the laser remelting method is applied for improving the profile of WAAM substrate surface. The simulation model of heat transfer and fluid flow in the laser remelting process is established, the influence of the laser power and the scanning speed on the surface-profile improvement is researched by simulation and verified by experiments, Based on that the remelting process parameters are optimized. Furthermore, based on the WAAM formed substrate, the LMD formed volumes are deposited directly, after surface milling and after laser remelting, respectively. Then the microstructure and the mechanical properties of the bonding interface are compared among the three process methods, the feasibility of the laser remelting method for improving the bonding interface performance is verified.

scholarly journals Context awareness in process monitoring of additive manufacturing using a digital twin

2022 ◽  
Author(s):  
Raven T. Reisch ◽  
Tobias Hauser ◽  
Benjamin Lutz ◽  
Alexandros Tsakpinis ◽  
Dominik Winter ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Process Monitoring ◽  
Context Awareness ◽  
Large Scale ◽  
Spatial Context ◽  
Context Aware ◽  
Cold Metal Transfer ◽  
Digital Twin ◽  
Local Anomaly ◽  
Wire Arc Additive Manufacturing

AbstractWire Arc Additive Manufacturing allows the cost-effective manufacturing of customized, large-scale metal parts. As the post-process quality assurance of large parts is costly and time-consuming, process monitoring is inevitable. In the present study, a context-aware monitoring solution was investigated by integrating machine, temporal, and spatial context in the data analysis. By analyzing the voltage patterns of each cycle in the oscillating cold metal transfer process with a deep neural network, temporal context was included. Spatial context awareness was enabled by building a digital twin of the manufactured part using an Octree as spatial indexing data structure. By means of the spatial context awareness, two quality metrics—the defect expansion and the local anomaly density—were introduced. The defect expansion was tracked in-process by assigning detected defects to the same defect cluster in case of spatial correlation. The local anomaly density was derived by defining a spherical region of interest which enabled the detection of aggregations of anomalies. By means of the context aware monitoring system, defects were detected in-process with a higher sensitivity as common defect detectors for welding applications, showing less false-positives and false-negatives. A quantitative evaluation of defect expansion and densities of various defect types such as pore nests was enabled.

Ultrasonic Nondestructive Testing for In-Line Monitoring of Wire-Arc Additive Manufacturing (WAAM)

2021 ◽  
Author(s):  
Md Shahjahan Hossain ◽  
Niraj Pudasaini ◽  
Alexander Reichenbach ◽  
Bishal Silwal ◽  
Hossein Taheri
Keyword(s):  
Additive Manufacturing ◽  
Nondestructive Testing ◽  
Ultrasonic Nondestructive Testing ◽  
Wire Arc Additive Manufacturing

PECVD of Amorphous Silicon Carbide from Trimethylsilane

1997 ◽  
Vol 495 ◽  
Author(s):  
J. T. Kelliher ◽  
M. Massuda ◽  
P. A. DiFonzo ◽  
T. R. Neal
Keyword(s):  
Silicon Carbide ◽  
Amorphous Silicon ◽  
Photoelectron Spectroscopy ◽  
Gas Flow ◽  
Stoichiometric Composition ◽  
Process Condition ◽  
Index Of Refraction ◽  
Process Conditions ◽  
Amorphous Silicon Carbide ◽  
Particle Count

ABSTRACTAmorphous silicon carbide (SiC) was deposited by plasma enhanced chemical vapor deposition (PECVD) in an Applied Materials (AMT5000) tool from sources of trimethylsilane (3MS) and either argon or nitrogen. A deposition rate of ≈ 800 nm/min on a 150 mm silicon wafer was achieved at 350°C. Process conditions investigated were temperature (200–400°C), power (100–600W), pressure (2–8 torr), gas flow rates, and spacing. Various process condition regimes generated a high particle count that was eliminated by controlling parameters of pressure and spacing. Ellipsometry and n&k Analyzer techniques determined the index of refraction. The index of refraction was in agreement between both tools and range from 1.79–2.36 depending on the 3MS flow (25–100 seem) and carrier gas. A Prometrix FT500 with a fixed index of refraction measured 49 points of thickness determined the uniformity. The SiC films stoichiometric composition was measured by X-ray Photoelectron Spectroscopy (XPS). Small quantities of oxygen or nitrogen were found. Additional properties examined were crystallinity, stress, and pinhole density. Dielectric constant was measured by CV techniques.

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