The Experts below are selected from a list of 8880 Experts worldwide ranked by ideXlab platform
Chunli Yang - One of the best experts on this subject based on the ideXlab platform.
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Gas metal arc welding of high nitrogen stainless steel with ar n2 o2 ternary Shielding Gas
Defence Technology, 2020Co-Authors: Zhu Ming, Chunli Yang, Chao Chen, Langping WangAbstract:Abstract High nitrogen stainless steel with nitrogen content of 0.75% was welded by Gas metal arc welding with Ar-N2-O2 ternary Shielding Gas. The effect of the ternary Shielding Gas on the retention and improvement of nitrogen content in the weld was identified. Surfacing test was conducted first to compare the ability of O2 and CO2 in prompting nitrogen dissolution. The nitrogen content of the surfacing metal with O2 is slightly higher than CO2. And then Ar-N2-O2 Shielding Gas was applied to weld high nitrogen stainless steel. After using N2-containing Shielding Gas, the nitrogen content of the weld was improved by 0.1 wt.%. As N2 continued to increase, the increment of nitrogen content was not obvious, but the ferrite decreased from the top to the bottom. When the proportion of N2 reached 20%, a full austenitic weld was obtained and the tensile strength was improved by 8.7%. Combined with the results of surfacing test and welding test, it is concluded that the main effect of N2 is to inhibit the escape of nitrogen and suppress the nitrogen diffusion from bottom to the top in the molten pool.
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Optimization of Shielding Gas composition in narrow gap GMA welding based on response surface methodology
The International Journal of Advanced Manufacturing Technology, 2018Co-Authors: Xiaoyu Cai, Chenglei Fan, Sanbao Lin, Chunli YangAbstract:In Gas metal arc (GMA) welding, metal melting behaviors and the weld geometry are affected by Shielding Gas composition. Helium has special properties, and it can provide a wider weld profile which is benefit for increasing sidewall penetration in narrow gap GMA welding. In this paper, helium was added to Shielding Gas for narrow gap GMA welding to ensure the sidewall penetration. The Shielding Gas includes argon, carbon dioxide, and helium. The statistical models for narrow gap GMAW weld bead sidewall penetration were developed using response surface methodology (RSM) based on central composite design (CCD). The developed models were checked for their adequacy and significance by analysis of variance (ANOVA), and the effects of Shielding Gas composition on sidewall penetration were studied. Finally, the optimal ternary Shielding Gas for tandem narrow gap GMA welding were obtained by numerical optimization using RSM. The largest sidewall penetration can be obtained under 79%Ar–10%CO2–11%He.
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effects of Shielding Gas composition on arc characteristics and droplet transfer in tandem narrow gap gma welding
Science and Technology of Welding and Joining, 2017Co-Authors: Chunli Yang, Xiangru Ji, Li HuAbstract:ABSTRACTThe effects of Shielding Gas composition in tandem narrow gap Gas metal arc welding were studied. The Shielding Gas included argon, carbon dioxide and helium. The arc characteristics and droplet transfer process were analysed. The results show that in the same welding parameters, the trail wire welding current is higher than the lead wire welding current. With the increase of carbon dioxide content, the welding currents of two wires decrease, and the trail wire droplet transfer mode transforms from spray transfer to projected transfer. With the increase of helium content, the welding currents increase and the lead wire droplet transfer mode transforms from projected transfer to spray transfer. The weld width is the largest when the Shielding Gas mixture is 80%Ar10%CO210%He.
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effects of Shielding Gas composition on arc properties and wire melting characteristics in narrow gap mag welding
Journal of Materials Processing Technology, 2017Co-Authors: Xiangru Ji, Chunli YangAbstract:Abstract At constant current, the arc voltage increases with increasing helium or CO2 content. At constant wire feed speed and constant voltage, as the helium or CO2 content increases, the welding current decreases. The arc length decreases significantly with the increase of CO2 content and arc core expands with the increase of helium content. When the Shielding Gas composition changes, arc properties and wire melting characteristics both change and the arc works at a new equilibrium point to keep the wire melting rate equal to wire feed speed. Shielding Gas with the addition of helium presents a bowl weld bead profile. The depth of sidewall fusion increases as helium content increases. The welding process and weld quality are good when the Shielding Gas is 80%Ar10%CO210%He.
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Effects of Shielding Gas composition on arc behaviors and weld formation in narrow gap tandem GMAW
The International Journal of Advanced Manufacturing Technology, 2017Co-Authors: Xiaoyu Cai, Chenglei Fan, Sanbao Lin, Chunli YangAbstract:In narrow gap Gas metal arc welding (GMAW), it is useful to understand the arc behaviors to ensure the weld quality. Arc behaviors are strongly affected by the Shielding Gas composition. In this study, a three-component Shielding Gas mixture was used in tandem narrow gap pulsed GMAW, and the effect of its composition on arc behaviors and weld formation were investigated. The Shielding Gas included argon, carbon dioxide, and helium. The arc behaviors and electrical characteristics were recorded by a high-speed camera and an electrical signal acquisition system. The results show that the arc behaviors in different Shielding Gas are different. The arc expands and the arc length decreases with the increase of CO2 content or helium content. The arc is the widest when the Shielding Gas is 80%Ar10%CO210%He. The weld shape was observed, and it was found that the weld width increases first and then decreases with increasing of the CO2 content. When the helium content is below 15%, the weld width increases as the helium content increases, but when the helium is 15%, the weld width drops due to the decrease of arc length. When the helium content is above 15%, the weld width continues to increase as the helium content increases. The largest weld width can be obtained in 80%Ar10%CO210%He.
Xiangru Ji - One of the best experts on this subject based on the ideXlab platform.
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effects of Shielding Gas composition on arc characteristics and droplet transfer in tandem narrow gap gma welding
Science and Technology of Welding and Joining, 2017Co-Authors: Chunli Yang, Xiangru Ji, Li HuAbstract:ABSTRACTThe effects of Shielding Gas composition in tandem narrow gap Gas metal arc welding were studied. The Shielding Gas included argon, carbon dioxide and helium. The arc characteristics and droplet transfer process were analysed. The results show that in the same welding parameters, the trail wire welding current is higher than the lead wire welding current. With the increase of carbon dioxide content, the welding currents of two wires decrease, and the trail wire droplet transfer mode transforms from spray transfer to projected transfer. With the increase of helium content, the welding currents increase and the lead wire droplet transfer mode transforms from projected transfer to spray transfer. The weld width is the largest when the Shielding Gas mixture is 80%Ar10%CO210%He.
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effects of Shielding Gas composition on arc properties and wire melting characteristics in narrow gap mag welding
Journal of Materials Processing Technology, 2017Co-Authors: Xiangru Ji, Chunli YangAbstract:Abstract At constant current, the arc voltage increases with increasing helium or CO2 content. At constant wire feed speed and constant voltage, as the helium or CO2 content increases, the welding current decreases. The arc length decreases significantly with the increase of CO2 content and arc core expands with the increase of helium content. When the Shielding Gas composition changes, arc properties and wire melting characteristics both change and the arc works at a new equilibrium point to keep the wire melting rate equal to wire feed speed. Shielding Gas with the addition of helium presents a bowl weld bead profile. The depth of sidewall fusion increases as helium content increases. The welding process and weld quality are good when the Shielding Gas is 80%Ar10%CO210%He.
Norman Mcpherson - One of the best experts on this subject based on the ideXlab platform.
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Visualisation and optimisation of Shielding Gas coverage during Gas metal arc welding
Journal of Materials Processing Technology, 2018Co-Authors: Ioannis Bitharas, Norman Mcpherson, W. Mcghie, D. Roy, Andrew J. MooreAbstract:Abstract The density gradients and flow characteristics of the Gas shield during Gas metal arc welding (GMAW) of DH36, higher strength ‘construction steel’, were visualised using schlieren imaging. A systematic study was undertaken to determine the effect of Shielding Gas flow rate, as well as changes in the nozzle stand-off and angle, on the weld quality. The schlieren images were used to validate 2D and 3D magnetohydrodynamic (MHD) finite element models of the interaction between the Ar Shielding Gas, the arc and the ambient atmosphere. Weld porosity levels were determined through x-ray radiography. Sufficient Shielding Gas coverage was provided at a minimum of 9 l/min pure Ar, irrespective of relatively large increases in the nozzle stand-off and angle. Using 80% Ar/20% CO2 Shielding Gas, and 86% Ar/12% CO2/2% O2 Shielding Gas with flux cored arc welding (FCAW-G), achieved good quality welds down to 5 l/min. The introduction of 12 l/min in production welding has been implemented with no compromise in the weld quality and further reductions are feasible.
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effect of Shielding Gas parameters on weld metal thermal properties in Gas metal arc welding
The International Journal of Advanced Manufacturing Technology, 2015Co-Authors: F H Ley, Alexander Galloway, Stuart Campbell, Norman McphersonAbstract:This study considered the effect of Shielding Gas parameters (composition, supply method and flow rate) on the post-weld thermal properties (thermal expansion, specific heat capacity, thermal diffusivity and thermal conductivity) of the weld metal in Gas metal arc welding. This is of importance as the thermal properties influence the temperature distribution and therefore the residual stresses and distortion present within the final structure. Due to the lack of accurate thermal data, computational modelling techniques (such as FEA and CFD) used for modelling the welding process generally make assumptions regarding the material thermal properties, and it is often the case that the parent material thermal properties are extended to the weld metal, introducing errors to the simulation. It was determined that the weld metal posses considerably different thermal properties to the DH36 grade steel parent material and that the Shielding Gas parameters significantly alter key thermal properties of the solidified weld metal. A lower Shielding Gas flow rate exhibited beneficial properties including a lower thermal expansion and higher specific heat capacity and thermal conductivity than a higher Shielding Gas flow rate.
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Artificial neural network optimisation of Shielding Gas flow rate in Gas metal arc welding subjected to cross drafts when using alternating Shielding Gases
Proceedings of the Institution of Mechanical Engineers Part B: Journal of Engineering Manufacture, 2014Co-Authors: Stuart Campbell, Alexander Galloway, F H Ley, Norman McphersonAbstract:This study implemented an iterative experimental approach in order to determine the Shielding Gas flow required to produce high quality welds in the Gas metal arc welding (GMAW) process with alternating Shielding Gases when subjected to varying velocities of cross drafts. Thus determining the transitional zone where the weld quality deteriorates as a function of cross draft velocity. An Artificial Neural Network (ANN) was developed using the experimental data that would predict the weld quality based primarily on Shielding Gas composition, alternating frequency and flowrate, and cross draft velocity, but also incorporated other important input parameters including voltage and current. A series of weld trials were conducted validate and test the robustness of the model generated. It was found that the alternating Shielding Gas process does not provide the same level of resistance to the adverse effects of cross drafts as a conventional argon/carbon dioxide mixture. The use of such a prediction tool is of benefit to industry in that it allows the adoption of a more efficient Shielding Gas flow rate, whilst removing the uncertainty of the resultant weld quality.
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PRICM: 8 Pacific Rim International Congress on Advanced Materials and Processing - GMAW Shielding Gas flow optimisation by refinement of nozzle geometry
Proceedings of the 8th Pacific Rim International Congress on Advanced Materials and Processing, 2013Co-Authors: Stuart Campbell, Alexander Galloway, Norman McphersonAbstract:With an ongoing demand to improve the efficiency of the Gas metal arc welding process, steps are being taken to reduce the Shielding Gas consumption. However, sufficient Shielding Gas coverage of the weld region is essential for the generation of high quality welds, and drafts can be detrimental to its efficiency. In industry, the general practise to ensure coverage is to increase the Shielding Gas flow rate, however, too high a flow rate can induce undesirable turbulence in the Shielding Gas column, whilst adding unnecessary cost to the process. A simplified computational fluid dynamics model has been generated, and validated through extensive experimental trials, to accurately model the Shielding Gas flow when subjected to the adverse effects of cross drafts. Several nozzle geometry changes have been investigated with the aim of improving the Shielding Gas column’s resistance to drafts, eliminating the requirement to increase the Shielding Gas flow rate.
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Techno-economic evaluation of reducing Shielding Gas consumption in GMAW whilst maintaining weld quality
The International Journal of Advanced Manufacturing Technology, 2012Co-Authors: Stuart Campbell, Alexander Galloway, Norman McphersonAbstract:A series of experimental trials have been conducted to investigate the effects of reducing the Shielding Gas consumption in Gas metal arc welding (GMAW). A number of claims have been made as to potential Shielding Gas savings in the GMAW process when using Gas-saving devices such as commercially available self-regulating valves. However, the literature and data available on weld quality obtained as a result of reducing the Shielding Gas flow rate is not readily available, so the thrust of this study is to present a new body of data to report on the technical and economic merits of controlling the Shielding Gas flow rate using (a) a conventional flow meter and (b) a ‘new to market’ self-regulating Gas-saving device. It has been determined that, in a draft-free environment, the Shielding Gas flow rate can be reduced to 6 L/min without diminishing weld quality, although a lower flow rate was more susceptible to the effects of cross-drafts, and the weld quality level was compromised. In addition to the economic savings associated with reducing the Shielding Gas flow rate, there are several weld aspects that have been found to be influenced by the Shielding Gas flow rate including penetration, leg length, distortion and peak temperature, thus suggesting that the heat transfer efficiency is affected by the Shielding Gas flow rate. This significant finding supports the view that there is scope to increase the travel speed when implementing a lower flow rate and, consequently, enhance productivity.
Markku Keskitalo - One of the best experts on this subject based on the ideXlab platform.
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The Influence of Shielding Gas on Strength of the Laser Welded Thin Sheet Lap Welds
Key Engineering Materials, 2018Co-Authors: Markku Keskitalo, Aappo Mustakangas, Mikko Hietala, Kari MäntyjärviAbstract:The laser welding is usable method for joining thin plates with low energy input and precise penetration control. When joining of very thin sheets such as 0.5 mm the shape of the weld must be complete in order to achieve a good strength of the joint. The part of the test welds were welded without Shielding Gas and other part of the test welds by using 65 mm Shielding Gas nozzle behind the key hole. The strength of the laser weld of 0.5 mm Austenitic stainless steel (ASS) plate was measured in welds without Shielding Gas and Ar shielded weld. The strength of the shielded weld joints was significantly better than the joint weld without Shielding Gas due to convex shielded welds. In addition the shielded welds were bright which improves the corrosion properties of the joint.
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The Influence of Shielding Gas Configurations on Formability of the Ferritic Stainless Steel Laser Weld
Physics Procedia, 2017Co-Authors: Markku Keskitalo, Mikko Hietala, Kari MäntyjärviAbstract:Abstract According to previous studies the careful argon Shielding of the weld is very important in order to achieve a ductile and formable laser weld of Ti-stabilized ferritic stainless steel. In practice it is often difficult to use the root Gas Shielding of the laser weld. The aim of this study was to determine the sufficient practise of Gas Shielding in order to achieve the ductile laser weld. According to Erichsen formability results the Shielding Gas nozzle in the post weld side must be used in order to reach the good formability of the laser weld. The single Shielding Gas pipe before the weld is not a sufficient method for the Gas Shielding. There is no need to use root Gas in order to achieve a ductile weld. The single Shielding Gas pipe before the weld can cause a uptake blast in the key hole and further oxidize the weld metal.
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The influence of Shielding Gas on the properties of laser welded stainless steel
2016Co-Authors: Markku Keskitalo, Jesper Sundqvist, K. Mentyjärvi, Ingemar Eriksson, Alexander KaplanAbstract:Argon is generally used as Shielding Gas for laser welding. As Argon is an inert Gas it doesnot have influence on the microstructure of the weld material or on the heat input of the weld,whereas ni ...
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laser welding of duplex stainless steel with nitrogen as Shielding Gas
Journal of Materials Processing Technology, 2015Co-Authors: Markku Keskitalo, Kari Mäntyjärvi, Jesper Sundqvist, John Powell, Alexander KaplanAbstract:Abstract Nitrogen loss from laser welding melts pools and can have a deleterious effect on weld toughness for duplex stainless steels. This effect can be alleviated by using nitrogen as the Shielding Gas during laser welding. The use of nitrogen results in increased austenite levels in the weld metal and improved toughness levels.
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the influence of the Shielding Gas to the static and dynamic strength properties of laser welded workhardened nitrogen alloyed austenitic stainless steel
Key Engineering Materials, 2013Co-Authors: Markku Keskitalo, Kari MäntyjärviAbstract:As an interstitial atom, nitrogen strengthens the structure of austenitic stainless steel (ASS). It therefore has been used to increase the strength of ASS. On the other hand, work hardening of ASS is a common method to increase the strength of the sheet product. When a work-hardened structure is welded, the strength properties decreases at the melted zone and the heat-affected zone (HAZ) of the weld. The nitrogen content can also be reduced by the effect of the heat input of the weld. Because the width of the soft area of the HAZ depends on the energy input of the weld, the strength of the weld depends on energy input. Therefore, laser welding provides better strength to the welded structure. The role of the Shielding Gas is also significant. Argon Shielding Gas is inert, but nitrogen used as a Shielding Gas can strengthen the weld metal and HAZ microstructure. In this study, the effect of different Shielding Gases in the laser welding of AISI 201 LN TR type work-hardened ASS are tested and the results are reported. Both non-destructive material and destructive material tests are performed. According to the results of the tensile test, the use of nitrogen as a Shielding Gas strengthens the laser-welded structure. The results of the low-cycle fatigue test show that fatigue strength improves when nitrogen is used as the Shielding Gas.
Manabu Tanaka - One of the best experts on this subject based on the ideXlab platform.
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influence of Shielding Gas composition on molten metal flow behavior during plasma keyhole arc welding process
Journal of Manufacturing Processes, 2020Co-Authors: Shinichi Tashiro, Anh Van Nguyen, Manh Huu Ngo, Hanh Van Bui, Manabu TanakaAbstract:Abstract The purpose of this investigation is to elucidate the behavior of molten metal flow inside weld pool during welding of Plasma Keyhole Arc Welding (PKAW). An observation of the behavior of three-dimensional (3D) molten metal flow inside weld pool during welding was carried out with the support of an advanced X-ray observation system. The results showed that the metal flow in pure Ar Shielding Gas case was in upward direction from bottom surface toward top surface of weld pool behind the keyhole. Meanwhile, the molten metal flow in Ar Shielding Gas mixed with 0.5 % O2 case was in downward direction from top surface toward bottom surface. The variation of convection flow inside weld pool as described above is a result of the variation of keyhole diameter and inclination angle of keyhole wall (keyhole profile) with (1) large around the top surface but narrow around the bottom surface in case of pure Ar and (2) narrow around the top surface but large around the bottom surface in case of Ar mixed with 0.5 % O2, which affect the direction and magnitude of shear force acting on weld pool surface. Consequently, only the very slight increase of oxygen content in argon Shielding Gas due to lowering of Shielding effect is found to significantly affect material and heat transport process in PKAW. The results also imply that when argon Shielding Gas with small amount of oxygen is used, deep and narrow weld penetration is more easily obtained similarly with AA-TIG welding process. However, its mechanism is suggested to be mainly related to the change in shear force due to keyhole shape deformation by the decrease of the surface tension rather than the change in direction and magnitude of Marangoni force.
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Influence of plasma characteristics on nitrogen mixing into Shielding Gas in helium Gas tungsten arc welding
Welding International, 2014Co-Authors: Shinji Kodama, Kazuki Sugiura, Shota Nakanishi, Daisuke Sakai, Yoshihiro Tsujimura, Manabu Tanaka, Anthony B. MurphyAbstract:The influence of welding condition on the mixing of atmospheric nitrogen into the arc plasma in helium Gas tungsten arc welding was analysed by numerical simulations. In order to evaluate the effects of the convection flow and the diffusion on the nitrogen mixing phenomenon, the distributions of the Peclet number were used. Elongation of the electrode length has low impact on the decrease of Shielding Gas concentration because the convection flow becomes dominant in this area, which indicates higher Peclet numbers. Meanwhile, nitrogen diffusion increases in the plasma area with a temperature of about 10,000 K, so that elongation of the arc length leads to a remarkable decrease of Shielding Gas concentration. Additionally, the impact of convection flow increases in the arc centre area where high-velocity plasma jet exists, and the Shielding Gas concentration tends to rise owing to higher welding current in the condition of sufficient Shielding Gas flow rate.
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effects of oxygen additions to argon Shielding Gas on gta weld shape
Isij International, 2003Co-Authors: H Fujii, Manabu Tanaka, Hiroyuki Sugiyama, Kiyoshi NogiAbstract:In order to investigate the effect of oxygen additions on the weld shape in Gas tungsten arc welding, bead-on-plate specimens were made of SUS304 stainless steel using O2-Ar mixed Shielding Gas with oxygen additions from 1 000 to 10 000 ppm. The weld bead cross-sections and the weld surface oxide layer were observed by optical microscopy after welding. The oxygen content in the weld metal was measured using an Oxygen/Nitrogen Analyzer. The weld depth/width ratio increases substantially as a result from the additions of oxygen to the argon Shielding Gas in the range of 3 000 to 5 000 ppm both for the 10 and 20 L/min Shielding Gas flow rates. When the oxygen addition contents are below 2 000 ppm or over 6 000 ppm, the weld D/W ratio decreases to approximately 0.2. The oxygen in the weld pool plays an important role as an active element affecting the Marangoni convection mode. The inward Marangoni convection occurs on the liquid pool surface when the oxygen in the weld is over 100 ppm, and hence the D/W ratio increases suddenly. The thicker oxide layer on the weld pool surface is not only a barrier for the oxygen to transfer and become a solute in the weld pool, but also prevents the weld pool from moving freely, and hence changes the weld pool shape.
