Optimization of gas metal arc welding parameters to weld AZ31B alloy using response surface methodology
05 Aug 2019-Vol. 6, Iss: 10, pp 106569
Abstract: In the present work, an effort has been made to optimize the external magnetic field (EMF) for mechanical properties of magnesium alloy AZ31B weld. Magnesium alloys have the potential to replace cold-rolled carbon steel (CRC) and hot- rolled carbon steel (HRC) from automotive manufacturing industries. It has good specific strength and low density compare to aluminum (Al) and iron (Fe). Its low melting and boiling point are the difficulties to get sound weld joints in high heat input fusion welding process. The design of experiments (DOE) based on the central composite design (CCD) has been used for analysis and optimization of the gas metal arc welds of magnesium alloy AZ31B. The effect of the external magnetic field(EMF) on the yield strength(YS), microhardness(H) and microstructure of weld samples studied. The optimal solutions of direct effect and interaction effect of process parameters like wire feed rate, welding speed, gas flow rate and external magnetic field are obtained by using Minitab-17 software. The insignificant terms related to the direct effect of process parameters or their interaction were removed from the mathematical model by backward elimination method. The change in microhardness at weld center is also critically analyzed. The direct effect of EMF on yield strength in comparison to other process parameters is 1% to 4%. The EMF 120 Gauss showed significant improvement in yield strength. At 120 Gauss; predicted optimum yield strength as 138 MPa and experimentally obtained mean yield strength is 137 MPa i.e. 96% of base metal with the significant increase in microhardness up to 100 HV at the weld center. The other variables kept constant as 5.7 m/min wire feed rate, 700 mm /min welding speed and 11 Ltr /min as gas flow rate. The study of changes in surface morphology is analyzed using field emission scanning electron microscopy. The fine grains with no traces of weld cracks and porosity are observed under the effect of the external magnetic field.
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TL;DR: In this article, a self-designed external compound magnetic field assisted gas metal arc welding process was developed to suppress the weld bead defects in high-speed welding, where the external magnetic field increased the metal transfer frequency and decreased the size of the droplet.
31 citations
TL;DR: In this paper, a three dimensional numerical model including the interactions among the arc plasma, filler metal and the external magnetic field was developed, and the distributions of some physical quantities including temperature, velocity, current density, arc plasma force and electromagnetic force were calculated.
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TL;DR: In this article, a magnetic generating device was proposed to regulate the transverse and backward flow of weld pool for high-speed gas metal arc welding (GMAW), and the effect of the compound EMF on the arc and droplet motion was studied by image acquisition system.
Abstract: A magnetic generating device was proposed to regulate the transverse and backward flow of weld pool for high-speed gas metal arc welding (GMAW). Compound external magnetic field (EMF) was simulated to verify the feasibility of designed magnetic generating device. The highest welding speed with good weld bead appearance was 1.7 m/min with the wire feed speed of 9.0 m/min when compound EMF was applied. The effect of the compound EMF on the arc and droplet motion was studied by image acquisition system. The suppression mechanism of the compound EMF on the undercut defect of high-speed GMAW was analyzed. The mechanism of the influence of the applied compound EMF on different welding speeds and welding currents was studied by the application of the compound EMF-assisted welding process, and low-cost, high-quality, and high-speed welding technology was realized.
9 citations
TL;DR: In this article, the relationship among welding process variables and welding bead geometric features as well as optimization of the welding quality is presented, and the influences of welding technological parameters (voltage, welding speed, and wire feed speed) on the welding geometry are revealed, and models correlating them are established.
Abstract: The profile of the welding bead changes with the welding process parameters during the gas metal arc welding (GMAW) process, the top reinforcement disappears, and the penetration becomes sunken when the excessive welding heat input is applied. However, little research work is specially planned to cope with the studying of welding bead under these circumstances. A systematic study of the relationships among the welding process variables and welding bead geometric features as well as optimization of the welding quality is presented. The influences of the welding technological parameters (voltage, welding speed, and wire feed speed) on the welding geometry were revealed, and the models correlating them were established. The features of the weld bead geometry were composed of top reinforcement width, top reinforcement height, penetration depth, bottom reinforcement width, and bottom reinforcement height. By the desirability function approach, the recommendation of suitable welding parameters to meet the contradicting demands of multiple bead geometric features is fulfilled. The microstructure in different welding regions and mechanical performances of the welding joints produced by the verification test were also studied.
4 citations
TL;DR: This study attempted to analyze and optimize the effect of an external magnetic field (EMF) on the aspect ratio and heat input for AZ31B weld joints that were welded using the gas metal arc welding process.
Abstract: This study attempted to analyze and optimize the effect of an external magnetic field (EMF) on the aspect ratio and heat input for AZ31B weld joints that were welded using the gas metal arc welding (GMAW) process. The response surface methodology (RSM) was adopted for the critical analysis, and subsequently, mathematical models were developed based on the experimental results. It was observed that the EMF and its interaction with the wire feed rate significantly affected the aspect ratio and heat input, respectively. At 119 G (magnetic field), 700 mm/min (welding speed), 5.8 m/min feed rate, and 11.5 L/min (gas flow rate), the aspect ratio was 2.26, and the corresponding heat input factor (HIf) was 0.8 with almost full weld penetration.
3 citations
Cites background or methods from "Optimization of gas metal arc weldi..."
...Schematic of the experimental setup [10]....
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...Sc e atic of t e ex eri e tal set [10]....
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...Optical micrograph of the weld zone: (a) with the magnetic field and (b) of the base metal [10]....
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...5% of AZ31B to avoid intermetallic weld cracking [2,10]....
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...In previous experiments [10], as a strategic process modification, an EMF has been used to control the mechanical properties and microstructure of GMA butt welds....
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References
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1,410 citations
TL;DR: In this paper, an overview of the hybrid welding process is given, including reports on gap bridging ability, changes in welding speed and weld penetration, overall weld quality, and changes in heat input to the material being welded.
Abstract: In this article, an overview of the hybrid welding process is given. After a short historic overview, a review of the fundamental phenomenon taking place when a laser (CO2 or Nd:YAG) interacts in the same molten pool as a more conventional source of energy, e.g. tungsten in-active gas, plasma, or metal inactive gas/metal active gas. This is followed by reports of how the many process parameters governing the hybrid welding process can be set and how the choice of secondary energy source, shielding gas, etc. can affect the overall welding process. An overview of the benefits and drawbacks of hybrid welding is presented, including reports on gap bridging ability, changes in welding speed and weld penetration, overall weld quality, and changes in heat input to the material being welded. This overview is followed by a few examples of industrial applications of hybrid welding. Finally, a section is devoted to explain about further work required in order to understand and tackle the hybrid welding process more efficiently in the future.In this article, an overview of the hybrid welding process is given. After a short historic overview, a review of the fundamental phenomenon taking place when a laser (CO2 or Nd:YAG) interacts in the same molten pool as a more conventional source of energy, e.g. tungsten in-active gas, plasma, or metal inactive gas/metal active gas. This is followed by reports of how the many process parameters governing the hybrid welding process can be set and how the choice of secondary energy source, shielding gas, etc. can affect the overall welding process. An overview of the benefits and drawbacks of hybrid welding is presented, including reports on gap bridging ability, changes in welding speed and weld penetration, overall weld quality, and changes in heat input to the material being welded. This overview is followed by a few examples of industrial applications of hybrid welding. Finally, a section is devoted to explain about further work required in order to understand and tackle the hybrid welding process more ...
286 citations
TL;DR: In this article, the effect of welding speed ranging from 5 to 30mm/s on 2-mm butt joint quality of friction stir welded AZ31B-H24 magnesium alloy was investigated to determine defects, microstructures, hardness and tensile properties.
146 citations
15 May 2010-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, double-sided arc welded and friction stir welded (FSWed) alloy sheet were studied at different strain rates. And the authors evaluated the strain-hardening exponents using the Hollomon relationship, the Ludwik equation and a modified equation.
Abstract: Microstructures, tensile properties and work hardening behavior of double-sided arc welded (DSAWed) and friction stir welded (FSWed) AZ31B-H24 magnesium alloy sheet were studied at different strain rates. While the yield strength was higher, both the ultimate tensile strength and ductility were lower in the FSWed samples than in the DSAWed samples due to welding defects present at the bottom surface in the FSWed samples. Strain-hardening exponents were evaluated using the Hollomon relationship, the Ludwik equation and a modified equation. After welding, the strain-hardening exponents were nearly twice that of the base metal. The DSAWed samples exhibited stronger strain-hardening capacity due to the larger grain size coupled with the divorced eutectic structure containing -Mg17Al12 particles in the fusion zone, compared to the FSWed samples and base metal. Kocks-Mecking type plots were used to show strain-hardening stages. Stage III hardening occurred after yielding in both the base metal and the welded samples. At lower strains a higher strain-hardening rate was observed in the base metal, but it decreased rapidly with increasing net flow stress. At higher strains the strain-hardening rate of the welded samples became higher, because the recrystallized grains in the FSWed and the larger re-solidified grains coupled with particles in the DSAWed provided more space to accommodate dislocation multiplication during plastic deformation. The strain-rate sensitivity evaluated via Lindholm's approach was observed to be higher in the base metal than in the welded samples. © 2010 Elsevier B.V. All rights reserved.
101 citations
TL;DR: In this article, gas tungsten arc welding was carried out, during which transverse oscillations of the arc were induced through the use of an alternating external magnetic field, and considerable refinement of the fusion zone grain structure was achieved.
Abstract: In an effort to refine the weld metal grain structure in α–β titanium alloys, gas tungsten arc welding was carried out, during which transverse oscillations of the arc were induced through the use of an alternating external magnetic field. At optimum values of oscillation amplitude and frequency in both the alloys investigated, considerable refinement of the fusion zone grain structure was achieved. This could be attributed to factors that include enhanced fluid flow, reduced temperature gradients, and a continually changing weld pool size and shape owing to the action of the imposed magnetic field. The reduction in the prior β grain size was shown to result in a notable increase in fusion zone tensile ductility. Post-weld annealing increased ductility in all cases, but the magnetically treated material continued to show a higher elongation than that of the untreated material even after post-weld heat treatment.
71 citations