Papers by Keyword: Weld Bead

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Authors: Jun Zhao, Ji Zhao, Lei Zhang, Cheng Fan, Fei Fei Han
Abstract: Getting the real-time information of spatial data, height and length of weld bead is the key point during the process of grinding and polishing large-scale part. To tackle this problem, a robot visual system is completed by building the double CCD and the laser on the mobile robot. Combining the image search algorithm with the image preprocessing algorithm in time domain, the laser single pixel feature line is obtained. The positions of each point in feature line are optimized by curve fitting so that the right spatial data and dimension are obtained. The result shows the proposed method can provides the precise information of weld bead, and the accuracy of measurement is within 0.15mm, as steady as repeatability.
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Authors: F. García-Vázquez, A. Aguirre, Ana Arizmendi-Morquecho, H.M. Hernández-García, L. Santiago-Bautista, J. Acevedo, B. Vargas-Arista
Abstract: Plasma Transferred Arc (PTA) process is increasingly used in applications where enhancement of wear, corrosion and heat resistance of metals surface is required. The shape of weld bead geometry affected by the PTA welding process parameters is an indication of the quality of the weld. PTA is a versatile method of depositing high-quality metallurgically fused deposits on relatively low cost surfaces. The overlay deposited is an alloy that is hard and more corrosion resistant than counterparts laid down by Gas Tungsten Arc Welding (GTAW) or Oxy Fuel Welding (OFW) processes. Weld deposits are characterized by very low levels of inclusions, oxides, and discontinuities. This process produces smooth deposits that significantly reduce the amount of post weld machining required. Metal-Mechanic industry continuously requires recovering tool steel components subjected to severe wear. The steel known as D2 is considered to be a high carbon, high chromium cold work tool steel. In this research, weld beads were deposited on D2 steel by using PTA process with different parameters as welding current and travel speed using base nickel filler metal. In order to evaluate the metallurgical features on the weld beads/substrate interface a microstructural characterization was performed by using Scanning Electron Microscopy (SEM) and to evaluate the mechanical properties was conducted the wear test.
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Authors: Kee Nam Song, Soo Sung Kim
Abstract: A spacer grid assembly, which is an interconnected array of slotted grid straps welded at the intersections to form an egg crate structure, is one of the core structural components of the nuclear fuel assemblies of a Pressurized light Water Reactor (PWR). The spacer grid assembly is structurally required to have enough buckling strength under lateral loads so that the nuclear fuel rods are maintained in a coolable geometry, and that control rods are able to be inserted. The ability of a spacer grid assembly to resist lateral loads is usually characterized in terms of its dynamic and static crush strengths. Since the crush strengths of a spacer grid assembly are known to depend on the weld qualities at the intersections of the slotted grid straps, high-tech welding methods, such as a TIG welding, LASER beam welding or Electron beam welding method, have been used recently in the nuclear fuel manufacturing fields. In this study, to meet the above requirements, two kinds of researches were carried out. First, by adjusting the LASER beam welding parameters, an optimum welding combination of the LASER beam welding parameters was obtained for welding a spacer grid assembly. Second, a new LASER beam welding technique was proposed to obtain a longer weld line and a smaller weld bead size by tilting the LASER beam. The buckling strength of the spacer grid welded by the new LASER beam welding technique was enhanced by up to 30 % when compared to that by the conventional LASER beam welding method.
147
Authors: F. García-Vázquez, H.M. Hernández-García, B. Vargas-Arista, A. Aguirre, E.E. Granda-Gutiérrez
Abstract: Among the different surface treatments used to improve the wear resistance of metallic materials, plasma transferred arc (PTA) is an attractive alternative to conventional techniques due to the intrinsic properties of its higher deposition rate, lower heat input and especially for the wide applicability of materials. The wide range of materials makes it possible to produce metallurgical bonding between the hardfacing layer and substrate material with very low dilution and distortion. Weld deposits are characterized by less level of inclusions, oxides, discontinuities and wear resistance. Metal-mechanic industry continuously requires recovering tool steel components subjected to severe wear. In this research Fe-based filler metal was deposited on D2 steel by using plasma transferred arc (PTA) process. The influence of Cr and Nb on Fe-based filler metal microstructure was investigated using scanning electron microscopy (SEM). In order to evaluate the mechanical properties were performed wear and hardness tests. The wear resistance and hardness values were compared with the results of a weld bead using nickel-based filler metal.
11
Authors: Dong Xia Li, Ying Mei, Fang Jia, Bao Chun Jia
Abstract: The effects of multiple repairing-weld and TIG-dressing on the fatigue property of high strength steel weld joints used in platform have been investigated. Through the fatigue tests on high strength steel welded joint samples, the life estimating formula is obtained after each time of repairing weld and TIG-dressing. The S-N curve and the equation after repairing weld and TIG-dressing are given. The work in this paper offers an important basis for the multiple repairing-weld of platforms.
467
Authors: Hua Wang, Yun Peng Zhang, Xiao Yu Zhang
Abstract: In this paper, the effect of welding current of the tungsten inert gas arc (TIG) welding process on weld quality of TZM alloy was investigated and the fracture microstructure and mechanical properties of the welding joints of TZM alloy was analyzed by x-ray flaw detection, metallographic microscopic analysis, scanning electron microscopy and mechanical properties test. The results indicate that the weld bead with excellent mechanical properties can be obtained using the welding process parameter with the welding current of 210A, welding speed of 4 mm/s and the argon gas flow rate of 8~12 L/min. The microstructure of weld presents the large columnar grains in the center of the weld bead and the equiaxed grains in heat-affected zone instead of the lamellar fiber texture of the TZM alloy matrix, which resulted in the weakened strength of the matrix and the improved plasticity of it.
867
Authors: Trinnachoke Eiammanussakul, Jirawut Taoprayoon, Viboon Sangveraphunsiri
Abstract: Magnetic wheel wall climbing robots are used in inspection of weld bead on large steel tanks. This research aims to develop the robot and tracking control algorithm to be more suitable for the inspection process. A laser-vision system was added on the robot to provide accurate weld bead detection. The simulation of the robot tracking along a weld bead by using nonlinear controller is demonstrated the effectiveness of the tracking control system.
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