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  • 301.
    Sundqvist, Jesper
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    Kaplan, Alexander
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    Shachal, L.
    Holo/Or Ltd.
    Brodsky, A.
    Holo/Or Ltd.
    Kong, Choon Yen
    TWI Ltd., Granta Park, Great Abington, Cambridge.
    Blackburn, Jon
    TWI Ltd., Granta Park, Great Abington, Cambridge.
    Assuncao, Eurico
    LAETA, IDMEC, Instituto Superior Técnico, Universidade de Lisboa.
    Quintino, Luisa
    LAETA, IDMEC, Instituto Superior Técnico, Universidade de Lisboa.
    Numerical optimization approaches of single-pulse conduction laser welding by beam shape tailoring2016Inngår i: Optics and lasers in engineering, ISSN 0143-8166, E-ISSN 1873-0302, Vol. 79, s. 48-54Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    While circular laser beams are usually applied in laser welding, for certain applications tailoring of the laser beam shape, e.g. by diffractive optical elements, can optimize the process. A case where overlap conduction mode welding should be used to produce a C-shaped joint was studied. For the dimensions studied in this paper, the weld joint deviated significantly from the C-shape of the single-pulse laser beam. Because of the complex heat flow interactions, the process requires optimization. Three approaches for extracting quantitative indicators for understanding the essential heat flow contributions process and for optimizing the C-shape of the weld and of the laser beam were studied and compared. While integral energy properties through a control volume and temperature gradients at key locations only partially describe the heat flow behaviour, the geometrical properties of the melt pool isotherm proved to be the most reliable method for optimization. While pronouncing the C-ends was not sufficient, an additional enlargement of the laser beam produced the desired C-shaped weld joint. The approach is analysed and the potential for generalization is discussed.

  • 302.
    Sundqvist, Jesper
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    Kim, Kyounghak
    Department of Welding and Joining Science Engineering, Graduate School, Chosun University.
    Bang, Hee-Seon
    Department of Welding and Joining Science Engineering, Chosun University.
    Bang, Hansur
    Department of Welding and Joining Science Engineering, Chosun University.
    Kaplan, Alexander
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    Numerical simulation of laser preheating of friction stir welding of dissimilar metals2018Inngår i: Science and technology of welding and joining, ISSN 1362-1718, E-ISSN 1743-2936, Vol. 23, nr 4, s. 351-356Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Friction stir welding, FSW, of harder metal alloys is difficult to perform, like here dissimilar welding of titanium alloy to stainless steel in butt joint configuration. One major limitation is tool wear which can be reduced by preheating with a laser beam. A mathematical model to calculate the tool forces during FSW was developed further. The calculations show that the laser beam reduces forces at the pin and shoulder of the FSW-tool, accompanied by reduced heat generation through the tool. Within its operating limits, the process has low sensitivity on the lateral position of the leading laser beam. The model supports the understanding and optimisation of the complex interaction zone of forces and heat around the FSW-tool.

  • 303.
    Sundqvist, Jesper
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    Manninen, Timo
    Outokumpu Stainless Oy.
    Heikkinen, Hannu-Pekka
    Outokumpu Stainless Oy.
    Anttila, Severi
    Materials and Production Engineering, University of Oulu, Oulu, Finland.
    Kaplan, A. F. H.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    Laser surface hardening of 11% Cr ferritic stainless steel and its sensitisation behaviour2018Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 344, s. 673-679Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    11% Cr ferritic stainless steel conforming to EN 1.4003 standard was surface hardened by a continuous-wave fibre laser beam. Both single-pass and multi-pass laser hardening was investigated. Different laser parameters were compared and their influence on hardness, microstructure, geometry of the hardened zone and sensitisation was investigated, especially for overlapping passes. The experiments showed that a surface hardness which is double that of the base material hardness was obtainable via martensitic phase transformation and high cooling rate, in spite of the low carbon and nitrogen content. This behaviour could be predicted from the chemical composition using the Kaltenhauser Ferrite Factor. Hardening at higher power levels gives more coarse-grained lath martensite but does not increase the hardness. Sensitisation was not a problem in single-pass hardening. However, the production of overlapping tracks could be detrimental to corrosion resistance in 11% Cr steel due to the formation of chromium carbides and nitrides.

  • 304.
    Svennungsson, Josefine
    et al.
    University West, Department of Engineering Science, 461 32 Trollhättan.
    Choquet, Isabelle
    University West, Department of Engineering Science, 461 32 Trollhättan.
    Kaplan, Alexander
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    Laser Welding Process: A Review of Keyhole Welding Modelling2015Inngår i: Physics Procedia, ISSN 1875-3892, E-ISSN 1875-3892, Vol. 78, s. 182-191Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Laser welding is used in several industrial applications. It can be distinguished between conduction mode and keyhole mode welding, between pulsed wave and cw laser welding and between CO2-lasers with a wavelength of 10 μm and various laser types of about 1 μm wavelength. A deeper understanding of laser welding allows improving weld quality, process control and process efficiency. It requires a complementary combination of precise modelling and experimental investigations. The here presented review focuses on modelling of laser keyhole welding, for both wavelength regimes. First, the fundamentals of the laser welding process and its physics such as beam propagation, keyhole formation and melt pool dynamics are addressed. The main approaches for modeling energy transfer from laser beam to keyhole surface as well as fluid flow in the material are then discussed. The most relevant publications are systematically structured, particularly categorized with regard to the respective physical phenomena addressed. Finally some open questions are underlined.

  • 305.
    Tokarev, V.
    et al.
    General Physics Institute of the Russian Academy of Science.
    Kaplan, Alexander
    An analytical modeling of time dependent pulsed laser melting1999Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 86, nr 5, s. 2836-2846Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The one-dimensional time dependent heat conduction equation for surface heating and a phase boundary (the so-called classical Stefan problem) has been solved in the absence of vaporization. For a rectangular laser pulse and constant material parameters, useful solutions have been determined for melt depth as a function of time both during and following the pulse. Based on the model, the intensity dependence of the melt depth is investigated. Two melting regimes-slow and fast-have been identified by comparison with previously reported data for silicon

  • 306.
    Tokarev, Vladimir
    et al.
    Technical University of Vienna.
    Kaplan, Alexander
    Suppression of melt flows in laser ablation: application to clean laser processing1999Inngår i: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 32, nr 13, s. 1526-1538Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    It is shown that in laser ablation of materials with large Prandtl numbers (mainly ceramics and polymers) a motion of the melt along the surface caused by the vapour plume pressure is essentially retarded for thin enough melt layers due to the onset of viscous friction. For polymers in nanosecond laser ablation this melt displacement can be obtained to be less than the ablation depth per pulse (which is typically 0.2-1 µm for nanosecond irradiation), when the absorption coefficient, α, and the kinematic viscosity, v, satisfy the condition α2v > 108 s-1. Thus, clean precise laser ablation for such polymers can be explained simply in terms of the thermal mechanism, without invoking the concept of photochemical decomposition, in terms of absorption coefficient, melt viscosity and pressure of the ablation plume on the irradiated surface. From this point of view, several factors facilitating clean laser ablation in multipulse irradiation are discussed. However, for metals (usually having a very small Prandtl number) the viscous friction has no significant effect on the retardation lateral melt flow to the periphery. The quality of the laser spot border can still be improved by using laser pulses shorter than 1 ps. In this case, in a shallow spot, the alternative (explosive) melt expulsion mechanism becomes predominant, producing material removal mainly transverse to the spot surface. Thus, the lateral (along the surface) component of melt expulsion appears to be strongly suppressed, having no chance to spoil the border of the spot.

  • 307.
    Tokarev, Vladimir N.
    et al.
    General Physics Institute of the Russian Academy of Science.
    Lazare, Sylvain
    Laboratorie de Physicochimie Moléculaire, CNRS, Université de Bordeaux.
    Kaplan, Alexander
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    Different regimes of viscous melt flow in laser ablation: from "clean" ablation to nanostructuring2006Inngår i: High-Power Laser Ablation VI: 7 - 12 May 2006, Taos, New Mexico, USA ; [SPIE's International Symposium on High-Power Laser Ablation VI] / [ed] Claude R. Phipps, Bellingham, Wash: SPIE - International Society for Optical Engineering, 2006, s. 9-23Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The paper reviews recent results on modeling a viscous liquid flow driven by ablation pressure. Based on the analysis of the Navier-Stokes equation various strongly different manifestations of this phenomenon are explained. These are: (i) a "clean" laser ablation, when laser spot has a clean sharp spot border, free from a re-solidified melt dross; (ii) a new form of material removal in laser ablation - expulsion on a poly(methyl methacrylate) target of long (up to 1 mm) nanofibers with a radius about 150-200 nm to the exterior of the spot under the action of a single pulse of KrF excimer laser; and (iii) a new way of laser surface nanostructuring - the formation of a surface foam having a structure of micro-pores interconnected with nanofilaments of diameters about 100 nm as a result of single pulse KrF laser irradiation of biopolymer films.

  • 308.
    Tokarev, V.N.
    et al.
    Russian Adademy of Sciences.
    Kaplan, Alexander
    Modelling of melt depth in wide range of laser pulse intensities1998Inngår i: Lasers in engineering (Print), ISSN 0898-1507, E-ISSN 1029-029X, Vol. 7, nr 3-4, s. 295-332Artikkel i tidsskrift (Fagfellevurdert)
  • 309.
    Torkamany, Mohammad
    et al.
    Department of Materials Engineering, Tarbiat Modares University, Department of Materials Science and Engineering,Tarbiat Modares University.
    Ghaini, Malek
    Department of Materials Engineering, Tarbiat Modares University, Department of Materials Science and Engineering,Tarbiat Modares University.
    Kaplan, Alexander
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    Combination of laser keyhole and conduction welding: Dissimilar laser welding of niobium and Ti-6Al-4V2016Inngår i: Optics and lasers in engineering, ISSN 0143-8166, E-ISSN 1873-0302, Vol. 79, s. 9-15Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Pulsed Nd:YAG laser welding of pure niobium plate to titanium alloy Ti-6Al-4V sheet in butt joint is studied regarding the laser/metal interaction modes. To obtain the optimized process parameters in dissimilar welding of Ti-6Al-4V/Nb, the melting ratio of laser beam energy for each weld counterpart is evaluated experimentally. Different laser welding modes of keyhole and conduction are predicted regarding the absorbed energy from the similar laser pulses on each weld counterpart. Laser keyhole and conduction welding were observed simultaneously through direct visualization of laser interaction with dissimilar metals using High Speed Imaging (HSI) system.

  • 310.
    Torkamany, Mohammad
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    Kaplan, Alexander
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    Ghaini, Malek
    Department of Materials Engineering, Tarbiat Modares University.
    Vänskä, Mikko
    Lappeenranta University of Technology, Laboratory of Laser Materials Processing.
    Salminen, Antti
    Lappeenranta University of Technology, Lappeenranta University of Technology, Laboratory of Laser Materials Processing.
    Hedegård, Joakim
    Swerea KIMAB AB, Swerea KIMAB AB, Joining Technology Centre.
    Wire deposition by a laser-induced boiling front2015Inngår i: Optics and Laser Technology, ISSN 0030-3992, E-ISSN 1879-2545, Vol. 69, s. 104-112Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In laser materials processing the addition of material by wire is an option for techniques like laser welding, laser cladding or rapid prototyping. The stability of the wire deposition is strongly dependent on the wire interaction with the laser beam. For leading position wire feeding, high speed imaging was applied to study the melt transfer from the wire tip to the workpiece during keyhole welding. The observations revealed that a very stable concave processing front forms at the wire tip. A boiling front is established as an extension of the keyhole and the melt film at the front is sheared downwards by the ablation pressure of boiling. The deposition of the molten wire into the weld zone is smooth and controllable. Various wire front geometries and melt transitions are compared for different parameters. The option of laterally oscillating the laser beam is investigated and the interaction mechanism involved is discussed. Wire deposition by inducing a boiling front is explained here for the first time, which should promote future applications use of this very promising technique.

  • 311.
    Tuominen, J.
    et al.
    Tampere University of Technology, Department of Materials Science.
    Näkki, J.
    Tampere University of Technology, Department of Materials Science.
    Poutala, J.
    Tampere University of Technology, Department of Engineering Design.
    Miettinen, J.
    Tampere University of Technology, Department of Engineering Design.
    Peltola, T.
    Technology Centre KETEK Ltd..
    Vuoristo, P.
    Tampere University of Technology, Department of Materials Science.
    Rasehorn, I.
    Centria University of Applied Sciences, Kokkola.
    Alam, M. M.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling. Department of Engineering Sciences and Mathematics, Luleå University of Technology.
    Kaplan, Alexander
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling. Department of Engineering Sciences and Mathematics, Luleå University of Technology.
    Fatigue behavior of laser clad round steel bars2015Inngår i: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 27, nr 1, artikkel-id 12006Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Laser cladding is an overlay welding method to manufacture high performance, fusion bonded metal, and metal matrix composite coatings on metallic substrates with low dilution. Owing to steep thermal gradients, rapid solidification, and possible mismatch in coefficients of thermal expansion between the coating and the substrate, laser cladding induces large tensile residual stresses in coating layer, potentially affecting the service life of clad component under external load-induced stresses. In this study, four-point bending and torsion fatigue tests were conducted on relatively large round laser clad steel bars to determine the effect of laser cladding on fatigue strength. Quenched and tempered 42CrMo4 steel clad with Inconel 625 and S355 structural steel clad with Stellite 21 were subjected to various stress levels for relatively large number of cycles with and without postweld heat treatment (PWHT). The results indicated that Stellite 21 decreased the fatigue life of S355 at all the applied loads, whereas Inconel 625 increased the fatigue life of 42CrMo4 at high loads but decreased at low loads. Applied PWHT did not show any positive influence on fatigue life.

  • 312.
    Volpp, Joerg
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    Brueckner, Frank
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling. Fraunhofer-Institute for Material and Beam Technology IWS, Dresden, German.
    Kaplan, Alexander
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    Track geometry variations in selective laser melting processes2019Inngår i: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 31, nr 2, artikkel-id 022310Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Selective laser melting processes are widely used for many industrial applications using a laser beam to melt preplaced powder materiallayer by layer to create technical parts. The building process of those structures requires remelting of adjacent tracks and layers in order toavoid cavities and achieve the joining of the new track to the previous track and layer. In order to achieve a sufficient overlap and minimizecavities, usually conservative processing parameters are chosen. A higher energy and powder usage efficiency would be achieved if knowingabout the formation process of the single tracks and their geometrical dimensions depending on the available powder. In this work, it isshown that the cross-sectional track geometry significantly varies within one layer. A simple model is developed describing the influence ofthe available powder for each track within one layer. Depending on the hatch distance, different variation patterns are observed andmodeled showing that the track variations are inherent phenomena of the process. It can be concluded that the variations of powder avail-ability can cause the geometric variations of the tracks.

  • 313.
    Volpp, Jörg
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    Prasad, Himani Siva
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    Kaplan, Alexander
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    Behavior of heated powder particles on solid surfaces2018Inngår i: Procedia Manufacturing, E-ISSN 2351-9789, Vol. 25, s. 365-374Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Powder particles applied through a powder nozzle as used e.g. in laser additive manufacturing or cladding processes are heated during their flight through the laser beam. The heating process and the interaction of the particle with the solid substrate were modeled in this work. In addition, the particle interaction with the solid substrate was observed using high speed imaging. At a high temperature and a high speed of the particles, the heat conduction into the base material is not fast enough to solidify the particles due to the short interaction time with the substrate.

  • 314.
    Volpp, Jörg
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Prasad, Himani Siva
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    Riede, M.
    Fraunhofer-Institute for Material and Beam Technology IWS, Winterbergstr. 28, 01277 Dresden, Germany.
    Brueckner, Frank
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling. Fraunhofer-Institute for Material and Beam Technology IWS, Winterbergstr. 28, 01277 Dresden, Germany.
    Kaplan, Alexander
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    Powder particle attachment mechanisms onto liquid material2018Inngår i: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 74, s. 140-143Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In order to achieve high powder and energy efficiencies of Direct Metal Deposition processes knowledge about the basic effects of the interaction of the particle on the liquid surface is mandatory. Characteristic zones on the melt pool surface were identified in high-speed images. In the melt pool area around the center of the laser beam illumination, particles immediately enter into the melt pool while in its vicinity the particles float on the melt pool until they incorporate. Closer to the solidification line, particles rest on the liquid surface and remain as surface roughness on the track after solidification.

  • 315.
    Vuorinen, Esa
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Pino, G
    Wiklund, Greger
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    Kaplan, Alexander
    Laser surface hardening of steel with ausferritic structure2008Inngår i: SMT22: 22nd international Conference on Surface Modification Technologies, Sept. 22-24, 2008, Trollhättan, Sweden, 2008Konferansepaper (Fagfellevurdert)
    Abstract [en]

    High strength steels can be produced by austempering of Si-containing steels. High toughness and good wear resistance are properties possible to achieve. Surface hardening of this group of steels can give an additional increase of the surface hardness and wear resistance. Laser surface hardening has been used in order to increase the surface hardness of the steel 55Si7. The effect of surface hardening on the ferritic-austenitic carbide- free microstructure created for this steel has been studied. Optical as well as scanning electron microscopy has been used in the characterization of the micro-structural changes.

  • 316.
    Weingartner, W.
    et al.
    Technical University of Vienna.
    Kaplan, Alexander
    Schuocker, D.
    Technical University of Vienna.
    Laser machining with melt removal through suction1996Inngår i: International journal of materials & product technology, ISSN 0268-1900, E-ISSN 1741-5209, Vol. 11, nr 3-4, s. 310-319Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In conventional laser machining processes the melt is removed by an intense gas stream, which ejects the liquid material usually in the direction of the laser beam. A new method is described here, whereby the molten material is sucked into a bore coaxial to the beam and then taken away by a fast horizontal gas jet. The vacuum in the suction bore is obtained by fast expansion of highly compressed air. This design is then used to cut 1.25 mm mild steel under the variation of several parameters. It shows very similar results to conventional cutting processes, only the characteristic appearance of the top and bottom kerf edge being changed upside down.

  • 317. Weingartner, W.
    et al.
    Schuöcker, D.
    Kaplan, Alexander
    Laser material processing with melt removal through suction1996Inngår i: Proceedings of the 6th European Conference on Laser Treatment of Materials: ECLAT '96, September 16-18 1996, Stuttgart / [ed] Friedrich Dausinger, Arbeitsgemeinschaft Wärmebehandlung und Werkstofftechnik e.V. , 1996, s. 895-903Konferansepaper (Fagfellevurdert)
  • 318.
    Wiklund, Greger
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    Akselsen, Odd Magne
    SINTEF Materials and Chemistry, P. O. Box 4760 Sluppen.
    Sørgjerd, Arve J.
    Kvaerner Verdal AS, Material Department.
    Kaplan, Alexander
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    Geometrical aspects of hot cracks in laser-arc hybrid welding2014Inngår i: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 26, nr 1, artikkel-id 12003Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Hot cracks were frequently found in double sided laser-arc hybrid welding thick section (20 mm) low carbon steel. Other research has usually investigated the metallurgical resolidification mechanisms of the welded metal alloy, but here possible relationships between the hot cracks and geometrical aspects of their surrounding weld and heat-affected zone cross sections were studied. The motivation behind this research was to identify guidelines for laser-arc hybrid welding to avoid hot cracks. Weld cross sections were used to analyze hot cracking because they are rather easy to prepare and straightforward to alter through the process parameters. In this study, hot cracks were found in a preferred geometrical window, namely, in the middle of the narrow deep region of the weld which was generated by the laser beam. From the cross section analysis, a first indicator was that a more inclined, converging shape of the lower part of the weld cross section can avoid hot cracks, associated with different energy input and resolidification front geometry. Significant reduction of the welding speed has avoided hot cracks, being a second indicator

  • 319. Wiklund, Greger
    et al.
    Kaplan, Alexander
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    Laser cladding of cast iron using a 12 kW CO2-laser combined with induction heating2005Inngår i: 10th NOLAMP Conference: the 10th Nordic Laser Materials Processing Conference, 17-19 August 2005, Luleå Sweden / [ed] Alexander Kaplan, Luleå: Luleå tekniska universitet, 2005, s. 217-224Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Laser surfacing experiments were carried out using high alloy high, strength compact graphite iron Darcast (3.5%C, 2%Si, 0.85%Mn, 0.9%Cu) and ductile cast iron SS0732 (3.4-3.85%C, 2.3-3.1%Si, 0.1-0.3%Mn) substrate materials with a view to developing a crack-free surfacing process for use on piston rings. The cladding material used was a nickel based chromium carbide powder. Tracks 20 mm wide and 1-2 mm thick were created using heat input of 1700-3000 J/mm; pre- and post-heating using induction heating equipment was used to prevent cracking. Based on the experiments, parameters suitable for laser surfacing of SS0732 piston rings were selected and applied

  • 320. Wiklund, Greger
    et al.
    Nilsson, T.
    Kaplan, Alexander
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    Laser hybrid welding of Zinc-coated ultra high strength steel2007Inngår i: 11th NOLAMP Conference: 11th NOLAMP Conference in Laser Processing of Materials ; Lappeenranta, August 20 - 22, 2007 / [ed] Veli Kujanpää, Lappeenranta: Lappeenranta University of Technology Press, 2007Konferansepaper (Fagfellevurdert)
  • 321. Wouters, Marc
    et al.
    Kaplan, Alexander
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    Powell, John
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    The influence of the joint gap on the strength of hybrid Nd:YAG laser-MIG welds2006Inngår i: Peer reviewed conference proceedings: PICALO 2006, 2nd Pacific International Conference on Applications of Lasers and Optics : April 3 - 5, 2006, Grand Hyatt Melbourne, Melbourne, Australia / [ed] Milan Brandt, Orlando, Fla.: Laser institute of America , 2006, s. 169-173Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents the results of an experimental and theoretical analysis of the effect of joint gap on the strength of hybrid laser-MIG welds. The welds were of the partial penetration butt type with various joint gaps but identical weld penetration. Impact testing established that a zero gap gave a weak weld because the weld geometry contained the equivalent of a sharp crack where the unwelded parts met each other. A small gap between the workpieces improved the weld impact strength as the sharp crack effect became dissipated. Further increases in gap width resulted in a weakening of the joint and this is the subject of a discussion on joint gap optimization

  • 322. Wouters, Marc
    et al.
    Powell, John
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Kaplan, Alexander
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    The influence of joint gap on the strength of hybrid Nd:yttrium-aluminum-garnet laser-metal inert gas welds2006Inngår i: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 18, nr 3, s. 181-184Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This article presents the results of an experimental and theoretical analysis of the effect of joint gap on the strength of hybrid laser-metal inert gas welds. The welds were of the partial penetration butt type with various joint gaps but identical weld penetration. Impact testing established that a zero gap gave a weak weld because the weld geometry contained the equivalent of a sharp crack where the unwelded parts met each other. A small gap between the workpieces improved the weld impact strength as the sharp crack effect became dissipated. Further increases in gap width resulted in a weakening of the joint and this is the subject of a discussion on joint gap optimization

  • 323. Wouters, Marc
    et al.
    Powell, John
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Kaplan, Alexander
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    The influence of weld geometry and fit-up on hybrid laser-MIG welding2005Inngår i: 10th NOLAMP Conference: the 10th Nordic Laser Materials Processing Conference, 17-19 August 2005, Luleå Sweden / [ed] Alexander Kaplan, Luleå: Luleå tekniska universitet, 2005, s. 371-381Konferansepaper (Fagfellevurdert)
  • 324.
    Yao, Y.
    et al.
    Jilin University and China FAW Group Corporation R&D Center.
    Wouters, Marc
    Powell, John
    Laser Expertise Ltd., Acorn Park Industrial Estate, Nottingham.
    Nilsson, Klas
    Luleå tekniska universitet.
    Kaplan, Alexander
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    Influence of joint geometry and fit-up gaps on hybrid laser-metal active gas (MAG) welding2006Inngår i: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 18, nr 4, s. 283-288Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This article presents the results of an experimental program to investigate the sensitivity of the hybrid laser-MAG welding process to gaps between the work pieces being welded. It was concluded that the minimum throat depth of the welds remained surprisingly stable for fillet welds as long as the metal active gas (MAG) parameters were set high enough to fill the gaps involved (up to a gap size of approximately 3 mm). If the MAG parameters were insufficient then the welding process collapsed with increasing gap widths.

  • 325. Yao, Y.
    et al.
    Wouters, Marc
    Powell, John
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Nilsson, Klas
    Kaplan, Alexander
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    The influence of joint geometry and fit-up gaps on hybrid laser-MIG welding2006Inngår i: 10th NOLAMP Conference: the 10th Nordic Laser Materials Processing Conference, 17-19 August 2005, Luleå Sweden / [ed] Alexander Kaplan, Luleå, 2006, s. 371-381Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents the results of an experimental program to investigate the sensitivity of the hybrid laser-MIG welding process to gaps between the work pieces being welded. It was concluded that the minimum throat depth of the welds remained surprisingly stable for fillet welds as long as the MIG parameters were set high enough to fill the gaps involved (up to a gap size of approximately 3 mm). If the MIG parameters were insufficient then the welding process collapsed with increasing gap widths.

    Fulltekst (pdf)
    FULLTEXT01
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