Papers by Keyword: Laser Welding

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Authors: Yukio Miyashita, Rattana Borrisutthekul, Jian Chen, Yoshiharu Mutoh
Abstract: Effect of the applying twin laser beam on the welding of AZ31 / A5052 dissimilar metals lap joint was studied. The direct welding and the welding with Al12Si filler wire were carried out. Flow behavior of the molten metal was analyzed by FEM simulation. For both welding methods, failure load of the joints increased by applying twin laser beam with reasonable beam distance. Twin laser beam technique could control temperature distribution and flow behavior of the molten metal.
Authors: Mikko Hietala, Antti Järvenpää, Markku Keskitalo, Kari Mäntyjärvi
Abstract: The study was performed to investigate the bending resistance of laser-welded sandwich panels (Vf-core). The main aim of the study was to determine the effect of the tensile strength on bending strength of the panel structures. Panels were manufactured using an ultra-high strength (UHS) and low strength (LS) steels with yield strengths of 1200 and 200 MPa, respectively. Secondly, the bending strength of the panel structures was compared with the conventional sheet steels to estimate the possibilities for weight reduction. Results showed that the UHS steel panels had significantly higher bending strength than panels of the LS steel. The bending strength in the weakest loading direction of the UHS panel was approximately four times higher than the one of LS steel panel. The panels made with UHS steel faceplates and LS steel cores had better bending strength than LS steel panels. In comparison to UHS sheet steel, 30% weight saving is estimated by using the geometry optimized UHS steel panel.
Authors: Michael F. Zaeh, Paul Gebhard, Sonja Huber, Markus Ruhstorfer
Abstract: On a global market, new products are subject to rising requirements regarding strength and quality. Simultaneously, the conservation of the environment and natural resources has become a key priority. One approach to these demands is the weight reduction of mechanical components by lightweight construction. The Transregional Collaborative Research Center (TR 10), funded by the German Research Foundation (DFG), is therefore working on the “Integration of forming, cutting and joining for the flexible production of lightweight space structures”. The use of light metals, like aluminium and composite materials is a main part in the TR10 process chain. This paper deals with the challenges of welding of light weight components made out of EN AW-6060. It shows the use and potentials of two innovative joining processes, particularly suited for welding aluminium. Especially developed for the fusion welding of aluminium components, BHLW (Bifocal Hybrid Laser Beam Welding), combines a Nd:YAG and a high power diode laser. The paper will give insight into the findings of the achieved results so far and line out the further proceedings with regard to critical parameters and their effect on the overall laser welding process. For the welding of aluminium composite materials, which play a big role in the TR10 process chain, Friction Stir Welding (FSW) is evaluated. As a solid state joining process, it can be used for the welding of materials that are hardly weldable with fusion welding techniques. In this paper, results of basic experiment for the joining of reinforced aluminium and the resulting process forces are presented.
Authors: A. Kouadri, Laurent Barrallier
Abstract: This study looks at the effect of laser welding on residual stresses in sheets of moulded magnesium alloy (AZ91). The modifications are significant even though they are localised along the weld line. The welding process produces a gradient of residual stresses from the weld line to the base metal and throughout the thickness of the weld zone. The distribution of these residual stresses has been qualitatively explained by the kinetics of cooling and by the nature of the multiphase material. Finally, it has been demonstrated that a pronounced crystallographic texture modifies local distribution of residual stresses. These results show that there is a complex coupling between the metallurgical, thermal and mechanical aspects generated by high power welding procedures.
Authors: Ai Qin Duan, Shui Li Gong
Abstract: In this paper, the keyhole of YAG laser welding 5A90 Al-Li alloy was observed and measured through the high speed camera. The characteristics of the keyhole and the effects of welding parameters were studied. The characteristics of the absorption of laser energy and the susceptivity for heat input in welding 5A90 were given. The results show that in this welding condition, the keyhole of laser welding 5A90 is nearly a taper and the highest temperature area is in the bottom. There are clear effects of heat input on the characteristics, especially the surface radius of keyhole and plasma/vapor in keyhole. Another phenomena is observed that sometime plasma/vapor could disappear in 0.3ms welding time, and this feature will be more remarkable as decrease of heat input. It shows that the absorption of energy is unsteady. It is known that when this instability reaches a certain value, an unsteady weld will be formed.
Authors: Ioan Catalin Mon, Mircea Horia Tierean, Eugen Cicala, Michel Pilloz, Iryna Tomashchuk, Pierre Sallamand
Abstract: This paper studies the ductile iron (DI) weldability using laser welding. For performing an Yb:YAG continuous laser was used, with a maximum power of 6 kW. The parametrical window power (P) - welding speed (S) was explored by carrying out the fusion lines on ductile iron plates without preheating, to determinate areas of weldability (complete penetration, correct geometry) to allow further characterization. The criteria for selection of focus areas were the geometry of the fusion lines and the absence of the welding defects. The unsatisfactory domains were characterized by: collapse of the melted metal, incomplete penetration, low fusion lines quality (geometry, compactness). In present study, several values of power and welding speed have been tested to identify their influence on geometry, compactness of the joints and mechanical properties. As result, the power-welding speed diagram for feasible domains of laser welding was generated.
Authors: Patrick Schmitz
Abstract: The transition towards renewable energy implicates more decentralized and time-dependent ways of energy generation. In order to deal with the resulting fluctuation in energy supply, local storage systems are necessary. Larger systems may consist of thousands of battery cells. Therefore, the reliable interconnection between the individual battery cells is the basic prerequisite for the production of these systems. It has been demonstrated that laser beam welding is a suitable process for the contacting of batteries. However, due to the high requirements regarding the heat input and the reproducibility of the joining process, further investigations are necessary. Within this work, experiments on pulsed laser beam welding of nickel-plated DC04 steel were conducted. Four different pulsed welding strategies were analyzed in a preliminary study in order to develop a method for obtaining suitable process parameters while reducing the amount of free parameters. Subsequently, a comparative study between the rectangular pulse, the shaped pulse, the spike pulse and the sloping pulse was carried out. The weld seam properties as well as the electrical and the mechanical properties of the connection joints were evaluated. The results presented in this paper indicate a high eligibility of pulsed laser beam welding as a joining process for the connection of battery cells. For all analyzed pulsed welding strategies a homogeneous weld seam without full penetration was observed. Similar electrical resistances for all strategies were measured despite the comparatively small total joint area for the discretely pulsed weld seams.
Authors: Piyarach Eutrirak, Viritpon Srimaneepong, Kanokwan Saengkiettiyut
Abstract: This paper investigates the quality and corrosion property of Ni-free Co-Cr alloy joints soldered and laser welded using filler. The soldered and laser-welded test specimens were sectioned at the center and rejoined by either soldering or laser welding using appropriate fillers. The joint area was analyzed using microfocus X-ray and the percentage of porosity, as a measure of joint quality, was calculated. The corrosion behavior of soldered and laser-welded test specimens was evaluated using a potentiodynamic polarization technique in a 0.9 wt.% NaCl solution, pH 2.3, at 37°C. The results indicated that the amount of porosity and cracks in soldered joints were less than those of the laser-welded joints, leading to a lower corrosion rate.
Authors: K. Shinozaki, M. Yamamoto, A. Kawasaki, T. Tamura, Peng Wen
Abstract: This study was carried out on the development of the evaluation method for solidification cracking susceptibility of Inconel600/SUS347 dissimilar weld metals during laser welding. Some dissimilar weld metals which have different ratios of Inconel600/SUS347 were prepared by TIG welding and then were remelted on the U-type hot cracking tester by laser. Solidification cracking behavior during hot cracking test was observed by a high speed camera and the dynamic strain, close to the solidification crack, was evaluated. It appeared that local critical strain, for the initiation of solidification crack, was obtained by this strain measurement method. So the solidification cracking susceptibility could be directly evaluated based on the critical strain for different dissimilar joint. By using this method, it was discovered that solidification cracking occurred most easily when the ratio of Inconel600/SUS347 is 40%/60%, in the case of the Inconel600/SUS347 dissimilar laser welded joints.
Authors: Hisashi Serizawa, Yuuki Asakura, Hirotaka Motoki, Daisuke Tanigawa, Masahiro Tsukamoto, Joon Soo Park, Hirotatsu Kishimoto, Akira Kohyama
Abstract: Silicon carbide fiber reinforced silicon carbide composite (SiC/SiC composite) is expected as a potential replacement of the current Zircaloy fuel cladding in the light-water reactor because of its many superiorities, where it is necessary to develop the end-cap seal of SiC/SiC composite cladding. In this research, the applicability of diode laser irradiation for joining between Zircaloy and SiC/SiC composite tubes was examined based on the caulking method. As the method for fitting two tubes, the screw cutting was conducted for the inner face of Zircaloy tube and the outer surface of SiC/SiC composite. In addition, as a method to improve the joinability of Zircaloy and SiC/SiC composite, titanium nanopowder was inserted into a gap between two tubes. The laser beam irradiation was circumferentially applied to the outer surface of Zircaloy tube. Although the mechanical caulking joint was successfully produced, the airtightness was insufficient for the end-caps of SiC/SiC composite cladding. However, the good adhesion between Zircaloy and SiC/SiC composite was partially produced as the result of the generation of all proportional solid solution between titanium and zirconium. Namely, it can be concluded that the circumferential diode laser irradiation with inserting titanium nanopowder between Zircaloy and SiC/SiC composite tubes would have a good potential for producing the caulking joint of two tubes.
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