The Experts below are selected from a list of 729 Experts worldwide ranked by ideXlab platform
C Z Ni - One of the best experts on this subject based on the ideXlab platform.
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temperature distribution and residual stresses during multipass Narrow Gap Welding of thick plates
Materials Science and Technology, 2006Co-Authors: Jijin Xu, L G Chen, C Z NiAbstract:AbstractIn a multipass Welding operation, the temperature distribution and residual stresses developed in the material change with each weld pass, and are therefore more complicated than those of single-pass Welding. In the present study, two methods – testing and finite element analysis (FEA) – were used to determine the temperature distribution in thick plate with Narrow Gap during multipass submerged arc Welding (SAW). The residual stresses on the top surface, bottom surface and along the thickness direction at some distance away from the weld line are presented. The results are compared with those calculated by FEA. These are used to validate the finite element model which is then used to appraise the weld performance.
P K Ghosh - One of the best experts on this subject based on the ideXlab platform.
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Assembling of thick-section HSLA steel with one seam per layer multi-pass PC-GMA Welding producing superior quality
Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2017Co-Authors: B. P. Agrawal, P K GhoshAbstract:Assembling of 25-mm-thick HSLA steel plate with extra Narrow Gap between the plates is done with the help of multi-pass one seam per layer pulse current gas metal arc Welding process maintaining vertical weld deposition. Assembling of thick plates is also made using conventional groove with commonly used procedure of multi-pass multi-seam per layer weld deposition. Distortion and shrinkage that developed in the weld joints have been suitably determined. The effects of Welding parameters in reference to weld thermal behavior on shrinkage stress and bending stress have been studied. The observations show that the use of one seam per layer technique allowing extra Narrow Gap Welding with properly selected parameters can improve quality of weld joint with respect to distortion and stresses. The effect of pulse parameters on weld quality is studied, correlated and discussed. Cost benefits of applying such a Welding technique have been justified with respect to consumption of less filler material and time for preparation of weld joint.
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ultra Narrow Gap Welding of thick section of austenitic stainless steel to hsla steel
Journal of Materials Processing Technology, 2017Co-Authors: Ramkishor Anant, P K GhoshAbstract:Abstract A substantially Narrow GMAW torch nozzle head has been designed that enables Narrowing down of weld groove up to a limit of just accommodating the nozzle in it where the groove wall of thick section virtually acts as a side wall of the nozzle head to produce a Narrowest possible butt Welding. A model of shielding gas flow dynamics and its flow rate in case of employing newly developed GMAW nozzle head has been studied at different projection angle of torch nozzle inside the Narrow groove of butt joint by using ANSYS-CFX(14.5) software. The utility aspect of such a Narrow nozzle head from the view point of smooth flow of shielding gas inside a close fitted ultra-Narrow weld groove has also been studied. The outcome of the analytical studies has been used to produce a defect free ultra-Narrow multi-pass weld by employing P-GMAW process with vertically placed electrode depositing single bead per layer in weld groove.
Jun Seog Yang - One of the best experts on this subject based on the ideXlab platform.
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Fatigue Crack Growth Rate and Fracture Resistance of Heat Affected Zone of Type 316L Stainless Steel With Narrow Gap Welds
Volume 6: Materials and Fabrication Parts A and B, 2011Co-Authors: Changheui Jang, Jun Seog YangAbstract:In nuclear power plants, the automated Narrow Gap Welding (NGW) technique has been widely used in joining pipes in primary coolant system. Meanwhile, to apply the leak-before-break (LBB) design, mechanical properties of the structural materials of piping systems should be evaluated, especially at various welded joints. In this study, the fatigue crack growth rate (FCGR) and fracture resistance of stainless steel weld fusion zone and nearby heat affected zone (HAZ) were evaluated to support the LBB application. Tests were performed at plant operating temperature (315°C) and room temperature. FCGR test results showed higher crack growth rate in HAZ and the weld fusion zone compare to the base metal. Fracture resistance tests showed higher fracture toughness in HAZ compared to the weld fusion zone. By analyzing the microstructures in the weld fusion zone and HAZ, their effects on crack growth rate were discussed. Also, the crack growth behavior in circumferential direction was compared with that in radial direction which was previously reported.Copyright © 2011 by ASME
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Effects of microstructure and residual stress on fatigue crack growth of stainless steel Narrow Gap welds
Materials & Design, 2010Co-Authors: Changheui Jang, Seung Jin Oh, Jun Seog YangAbstract:Abstract The effects of weld microstructure and residual stress distribution on the fatigue crack growth rate of stainless steel Narrow Gap welds were investigated. Stainless steel pipes were joined by the automated Narrow Gap Welding process typical to nuclear piping systems. The weld fusion zone showed cellular–dendritic structures with ferrite islands in an austenitic matrix. Residual stress analysis showed large tensile stress in the inner-weld region and compressive stress in the middle of the weld. Tensile properties and the fatigue crack growth rate were measured along and across the weld thickness direction. Tensile tests showed higher strength in the weld fusion zone and the heat affected zone compared to the base metal. Within the weld fusion zone, strength was greater in the inner weld than outer weld region. Fatigue crack growth rates were several times greater in the inner weld than the outer weld region. The spatial variation of the mechanical properties is discussed in view of weld microstructure, especially dendrite orientation, and in view of the residual stress variation within the weld fusion zone. It is thought that the higher crack growth rate in the inner-weld region could be related to the large tensile residual stress despite the tortuous fatigue crack growth path.
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Effects of microstructure and residual stress on fatigue crack growth of stainless steel Narrow Gap welds
Materials and Design, 2010Co-Authors: Changheui Jang, Pyung Yeon Cho, Minu Kim, Seung Jin Oh, Jun Seog YangAbstract:The effects of weld microstructure and residual stress distribution on the fatigue crack growth rate of stainless steel Narrow Gap welds were investigated. Stainless steel pipes were joined by the automated Narrow Gap Welding process typical to nuclear piping systems. The weld fusion zone showed cellular-dendritic structures with ferrite islands in an austenitic matrix. Residual stress analysis showed large tensile stress in the inner-weld region and compressive stress in the middle of the weld. Tensile properties and the fatigue crack growth rate were measured along and across the weld thickness direction. Tensile tests showed higher strength in the weld fusion zone and the heat affected zone compared to the base metal. Within the weld fusion zone, strength was greater in the inner weld than outer weld region. Fatigue crack growth rates were several times greater in the inner weld than the outer weld region. The spatial variation of the mechanical properties is discussed in view of weld microstructure, especially dendrite orientation, and in view of the residual stress variation within the weld fusion zone. It is thought that the higher crack growth rate in the inner-weld region could be related to the large tensile residual stress despite the tortuous fatigue crack growth path. © 2009 Elsevier Ltd. All rights reserved.
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Prediction of Weld Residual Stress of Narrow Gap Welds
Transactions of The Korean Society of Mechanical Engineers A, 2010Co-Authors: Jun Seog YangAbstract:The conventional Welding technique such as shield metal arc Welding has been mostly applied to the piping system of the nuclear power plants. It is well known that this Welding technique causes the overheating and Welding defects due to the large groove angle of weld. On the other hand, the Narrow Gap Welding(NGW) technique has many merits, for instance, the reduction of Welding time, the shrinkage of weld and the small deformation of the weld due to the small groove angle and Welding bead width comparing with the conventional welds. These characteristics of NGW affect the deformation behavior and the distribution of Welding residual stress of NGW, thus it is believed that the residual stress results obtained from conventional Welding procedure may not be applied to structural integrity evaluation of NGW. In this paper, the Welding residual stress of NGW was predicted using the nonlinear finite element analysis to simulate the thermal and mechanical effects of the NGW. The present results can be used as the important information to perform the flaw evaluation and to improve the weld procedure of NGW.
Jijin Xu - One of the best experts on this subject based on the ideXlab platform.
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temperature distribution and residual stresses during multipass Narrow Gap Welding of thick plates
Materials Science and Technology, 2006Co-Authors: Jijin Xu, L G Chen, C Z NiAbstract:AbstractIn a multipass Welding operation, the temperature distribution and residual stresses developed in the material change with each weld pass, and are therefore more complicated than those of single-pass Welding. In the present study, two methods – testing and finite element analysis (FEA) – were used to determine the temperature distribution in thick plate with Narrow Gap during multipass submerged arc Welding (SAW). The residual stresses on the top surface, bottom surface and along the thickness direction at some distance away from the weld line are presented. The results are compared with those calculated by FEA. These are used to validate the finite element model which is then used to appraise the weld performance.
Akito Nishijima - One of the best experts on this subject based on the ideXlab platform.
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Solidification cracking susceptibility of modified 9Cr1Mo steel weld metal during hot-wire laser Welding with a Narrow Gap groove
Welding in the World, 2014Co-Authors: Rittichai Phaoniam, Kenji Shinozaki, Motomichi Yamamoto, Kota Kadoi, Akito Nishijima, Masayuki YamamotoAbstract:Hot-wire laser Welding with a Narrow Gap groove was applied to ASTM A213 grade T91 steel in the application of ultra super critical boilers. A filler wire according to AWS A 5.28: ER90S-G was used. The effect of the depth-to-width ratio (D/W) of a weld shape on the susceptibility to solidification cracking was investigated. With a groove width of 3 mm, solidification cracking did not occur with a D/W ratio of less than 0.6 and more than 1.2. The hot-wire laser Welding method with a Narrow Gap groove seemed to be efficient for practical use, when the higher D/W condition was used without solidification cracking. The high temperature strain, which occurred during solidification, was computationally calculated in order to make clear the effect of D/W ratios on the susceptibility of solidification cracking in theory. From in situ observation using a high-speed camera of the hot-wire laser Welding phenomena, a three-dimensional Finite Element Method (FEM) was simulated to estimate an equivalent plastic strain in the weld metal during Welding. An approach to the moving heat source consistent with such phenomenon was proposed and validated based on experimental measurements. The simulation results presented that a moving heat source by hot-wire laser Welding was able to produce a particular weld shape at a higher D/W ratio with a lower strain rate, which corresponded with the relationship between D/W ratios and solidification cracking in experiments. Therefore, such a hybrid process is a very interesting alternative process to reduce the solidification cracking in Narrow Gap Welding, especially in modified 9Cr1Mo steel.
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Development of a highly efficient hot-wire laser hybrid process for Narrow-Gap Welding—Welding phenomena and their adequate conditions
Welding in the World, 2013Co-Authors: Rittichai Phaoniam, Kenji Shinozaki, Motomichi Yamamoto, Kota Kadoi, Syoko Tsuchiya, Akito NishijimaAbstract:The purpose of this work is to develop hot-wire laser Welding for Narrow-Gap joints. Test pieces of ASTM A 304 stainless steel with a Gap width of 3 mm were used. With Welding by tentative filler rod made of Inconel 600 alloy, melting phenomena of the molten pool and the weld bead formation during Welding were investigated by in situ observation using a high-speed camera. Variations in the main Welding parameters such as wire current, wire feeding position, laser irradiation angle, and wire feeding angle were investigated to determine appropriate conditions. Experiments showed that under the optimum Welding conditions, hot-wire laser Welding was able to produce complete weld deposition with very low dilution of the base metal. An experiment on laser beam reflection indicated that the laser beam reflected from the molten pool was a crucial phenomenon to explain the formation of the weld bead, especially in terms of melting the side groove wall of the base metal. Welding parameters as mentioned above significantly affected weld quality. Furthermore, in the case of Welding with filler wire ER NiCrCoMo-1, the Vickers hardness distribution along the transverse Welding direction was examined to evaluate weld properties and the bonding strength at the fusion interface was examined in a tensile test, and the results showed that there was no great difference in the hardness profile throughout the cross section of the weld plate. Additionally, metallurgical examination of the fracture surface revealed the rupture occurred at the weld metal, probably because the bonding at the fusion interface was stronger than the weld metal. Therefore, the development of laser Welding with hot wire can advance the multi-pass weld for an ultra-Narrow-Gap joint.
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development of a highly efficient hot wire laser hybrid process for Narrow Gap Welding Welding phenomena and their adequate conditions
Welding in The World, 2013Co-Authors: Rittichai Phaoniam, Kenji Shinozaki, Motomichi Yamamoto, Kota Kadoi, Syoko Tsuchiya, Akito NishijimaAbstract:The purpose of this work is to develop hot-wire laser Welding for Narrow-Gap joints. Test pieces of ASTM A 304 stainless steel with a Gap width of 3 mm were used. With Welding by tentative filler rod made of Inconel 600 alloy, melting phenomena of the molten pool and the weld bead formation during Welding were investigated by in situ observation using a high-speed camera. Variations in the main Welding parameters such as wire current, wire feeding position, laser irradiation angle, and wire feeding angle were investigated to determine appropriate conditions. Experiments showed that under the optimum Welding conditions, hot-wire laser Welding was able to produce complete weld deposition with very low dilution of the base metal. An experiment on laser beam reflection indicated that the laser beam reflected from the molten pool was a crucial phenomenon to explain the formation of the weld bead, especially in terms of melting the side groove wall of the base metal. Welding parameters as mentioned above significantly affected weld quality. Furthermore, in the case of Welding with filler wire ER NiCrCoMo-1, the Vickers hardness distribution along the transverse Welding direction was examined to evaluate weld properties and the bonding strength at the fusion interface was examined in a tensile test, and the results showed that there was no great difference in the hardness profile throughout the cross section of the weld plate. Additionally, metallurgical examination of the fracture surface revealed the rupture occurred at the weld metal, probably because the bonding at the fusion interface was stronger than the weld metal. Therefore, the development of laser Welding with hot wire can advance the multi-pass weld for an ultra-Narrow-Gap joint.
