JLA Vol:15 Iss:4 (Welding of thick austenitic stainless steel using Nd:yttrium–aluminum–garnet laser with filler wire and hybrid process)
Authors:
Tommi Jokinen
Miikka Karhu
VTT Industrial Systems, P.O. Box 17021, FIN 53851 Lappeenranta, Finland
Veli Kujanpa¨a¨
Lappeenranta University of Technology, P.O. Box 20, FIN 53851 Lappeenranta, FinlandAutogenous laser welding has shown many advantages over traditional welding methods in numerous applications. However, there could be even more applications, but due to the power levels of present high power lasers, depth of penetration is limited. One way to overcome this limitation is to use multipass laser welding, in which a narrow gap and a filler wire are applied. By this process thick sections can be welded with a smaller heat inpu...
$25.00
JLA Vol:19 Iss:4 (Experimental observation of keyhole shapes in the laser welding of aluminum blanks)
Authors:
B. J. Aalderink
Netherlands Institute for Metals Research, P.O. Box 217, 7500 AE Enschede, The Netherlands
R. G. K. M. Aarts
University of Twente, Laboratory of Mechanical Automation, P.O. Box 217, 7500 AE Enschede, The Netherlands
D. F. de Lange
Netherlands Institute for Metals Research, P.O. Box 217, 7500 AE Enschede, The Netherlands
J. Meijer
University of Twente, Laboratory of Mechanical Automation, P.O. Box 217, 7500 AE Enschede, The NetherlandsA camera-based in situ monitoring system for the Nd:yttrium–aluminum–garnet laser keyhole welding process of aluminium has been developed. The...
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JLA Vol:9 Iss:4 (The application of external feedback in the laser spectroscopy of nonlinear media)
Authors:
B. V. Anikeev
D. V. Sin'ko
Department of Laser Physics, Volgograd State University, 2‐aya Prodolnay 30, Volgograd 400 062, RussiaA new spectroscopic technique to gain information on the nonlinear constants of optical materials is presented. This technique is made possible due to the point that the application of an external controlled negative feedback (CNF) circuit to an intracavity nonlinear cell results in the generation of extended boundaries of the stability for the laser beam. This effect is analyzed using a semiclassical set of equations that govern laser oscillation. Measurements are made on systems containing either an instantaneous CNF circuit o...
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JLA Vol:4 Iss:1 (Combustion‐Assisted Laser Cutting of a Difficult‐to‐Machine Superalloy)
Authors:
P. A. Molian
M. BaldwinIn laser cutting, the largest single application of lasers in manufacturing, the assist gas plays an important role in affecting the cutting performance. The assist gas is usually oxygen or an inert gas. In this work a mixture of acetylene and oxygen was employed to create combustion reactions during CO2 laser cutting that enabled an improvement in the cutting speed, and cut quality of a difficult‐to‐machine superalloy. A comparison with laser cutting of a plain carbon steel under identical conditions was also made to determine the usefulness of combustion energy. Results indicate that both cutting speed and qual...
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JLA Vol:14 Iss:1 (Physical–computational model to describe the interaction between a laser beam and a powder jet in laser surface processing)
Authors:
O. O. Diniz Neto
Array
R. Vilar
Departamento de Engenharia de Materiais, Instituto Superior Te´cnico, 1049-001 Lisboa, PortugalFrequently laser surface treatments use a powder jet in conjunction with the laser beam. In this study we present a physical–computational model to describe the interaction between a laser beam and a powder jet. The model can be used to calculate the spatial distribution of particle temperature and laser beam attenuation at any moment and all over the region where the laser and particle beams interact. In calculating particle temperature, the attenuation of the laser beam by the particles themselves is taken into acc...
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JLA Vol:18 Iss:2 (Fabrication of titanium microchannels using laser-assisted thermochemical wet etching)
Authors:
S. W. Son
M. K. Lee
K. H. Oh
S. H. Jeong
Department of Mechatronics, Gwangju Institute of Science and Technology, 1 Oryongdong Bukgu, Gwangju, 500-712 Republic of KoreaA fabrication method of titanium microchannels of an aspect ratio up to 16 and channel width of 10–30 μm is developed using laser-assisted thermochemical wet etching. For the fabrication of deep channel, the workpiece was repeatedly etched over the same path with the control of process parameters. The cross-sectional profile of the microchannel varied between a V shape and a U shape, depending largely upon the laser beam power and etchant concentration. Bubb...
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JLA Vol:25 Iss:5 (Heat transfer and fluid flow in additive manufacturing)
Authors:
A. Raghavan
H. L. Wei
T. A. Palmer
T. DebRoy
Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802In laser-based direct energy deposition additive manufacturing, process control can be achieved through a closed loop control system in which thermal sensing of the melt pool surface is used to adjust laser processing parameters to maintain a constant surface geometry. Although this process control technique takes advantage of important in-process information, the conclusions drawn about the final solidification structure and mechanical properties of the deposited material are li...
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JLA Vol:23 Iss:4 (Evaluation of the bone repair in defects grafted with hydroxyapatite and collagen membrane combined with laser therapy in rats)
Authors:
Marcelo Rodrigues da Cunha
Luanda de Abreu Figueira
Joa˜o Paulo Mardegan Issa
Ricardo Alexandre Junqueira Calzzani
Daniele Cristina do Prado Ribeiro
Amilton Iatecola
Mariane Silva Pettian
ArrayBone regeneration is the result of cellular events such as osteogenesis and neovascularization. However, implantation of autogenous grafts may be necessary in cases of bone mass loss due to high impact trauma. The disadvantages of the latter approach include morbidity of the donor area. Biomaterials represent an alternative for bone restoration. The most widely used compounds are collagen or hydroxyapat...
$25.00
JLA Vol:6 Iss:2 (CO<sub>2</sub> shielding gas effects in laser welding mild steel)
Authors:
D. H. Abbott
C. E. AlbrightThe most widely used shielding gases for laser welding of steels are helium and argon. Helium produces significantly more penetration than argon in penetration‐mode laser beam welding. Another gas that has been proposed as an alternative to these inert gases is carbon dioxide. The benefits of using carbon dioxide as a shielding gas for laser welding are that it costs less than helium and argon and that it provides nearly the same penetration as helium. The major drawback to its use as a shielding gas for mild steel is that it can cause porosity and other weld discontinuities. In this investigation helium and carbon dioxide were...
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JLA Vol:16 Iss:3 (Solidification model of laser cladding with wire feeding technique)
Authors:
Chien-Fu Hung
Jehnming Lin
Department of Mechanical Engineering, National Cheng Kung University, Tainan 701, TaiwanThe object of this study is to investigate the solidification problem in laser cladding with the wire feeding technique. The solidification phenomenon of laser cladding was analyzed by numerical simulation and experimental visualization. Good agreement has been obtained for 304 stainless steel wires cladding on round tubes and it transpires that there were three basic modes of clad profiles: thinning, thickening, and wavering of the clad thickness at different velocity settings between the feeding wire and the substrate in laser wire cladding. ©...
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