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V Balasubramanian - One of the best experts on this subject based on the ideXlab platform.
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electrochemical corrosion behaviour of stir zone of friction stir welded dissimilar joints of aa6061 aluminium az31b magnesium alloys
Transactions of Nonferrous Metals Society of China, 2017Co-Authors: Kamal R Jayaraj, S. Malarvizhi, V BalasubramanianAbstract:Abstract Joining of dissimilar metals will offer many advantages in transportation sectors such as fuel consumption, weight reduction and emission reduction. However, joining of aluminium (Al) alloys with magnesium (Mg) alloys by Fusion Welding Process is very complicated. Friction stir Welding (FSW) is a feasible method to join these two dissimilar alloys. Mixing these two metals together in stir zone (SZ) leads to poor corrosion resistance. In this investigation, an attempt has been made to understand the corrosion resistance of SZ of FSWed dissimilar joints of AA6061 Al alloy and AZ31B Mg alloy. Potentiodynamic polarization test was conducted by varying chloride ion concentration, pH value of the NaCl solution and exposure time. The corroded surfaces were analyzed using optical microscopy, scanning electron microscopy and XRD techniques. Of these three factors investigated, exposure time is found to be the most significant factor to influence the corrosion behaviour of SZ of friction stir welded dissimilar joints of Al/Mg alloys.
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Electrochemical corrosion behaviour of stir zone of friction stir welded dissimilar joints of AA6061 aluminium–AZ31B magnesium alloys
Transactions of Nonferrous Metals Society of China, 2017Co-Authors: R. Kamal Jayaraj, S. Malarvizhi, V BalasubramanianAbstract:Abstract Joining of dissimilar metals will offer many advantages in transportation sectors such as fuel consumption, weight reduction and emission reduction. However, joining of aluminium (Al) alloys with magnesium (Mg) alloys by Fusion Welding Process is very complicated. Friction stir Welding (FSW) is a feasible method to join these two dissimilar alloys. Mixing these two metals together in stir zone (SZ) leads to poor corrosion resistance. In this investigation, an attempt has been made to understand the corrosion resistance of SZ of FSWed dissimilar joints of AA6061 Al alloy and AZ31B Mg alloy. Potentiodynamic polarization test was conducted by varying chloride ion concentration, pH value of the NaCl solution and exposure time. The corroded surfaces were analyzed using optical microscopy, scanning electron microscopy and XRD techniques. Of these three factors investigated, exposure time is found to be the most significant factor to influence the corrosion behaviour of SZ of friction stir welded dissimilar joints of Al/Mg alloys.
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Optimizing difFusion bonding parameters to maximize the strength of AA6061 aluminum and AZ61A magnesium alloy joints
Experimental Techniques, 2014Co-Authors: M. Joseph Fernandus, V Balasubramanian, T Senthilkumar, S RajakumarAbstract:The main difficulty when joining magnesium (Mg) and aluminum (Al) alloys by Fusion Welding Process lies in the existence of oxide films and formation of brittle intermetallic in the weld region. However, solid-state Welding Processes such as friction Welding and difFusion bonding are suitable Processes to join these two materials. The difFusion bonding Process parameters such as bonding temperature, bonding pressure, holding time, and surface roughness of the bond specimen play a major role to determine the joint strength. In this investigation, an attempt was made to develop empirical relationships to predict the lap shear strength and bonding strength of difFusion bonded dissimilar joints of AZ61A magnesium and AA6061 aluminum alloys, incorporating the above-mentioned parameters. Response surface methodology (RSM) was applied to optimize the difFusion bonding Process parameters to attain the maximum shear strength and bonding strength of the joint. From this investigation, it is found that the bonds fabricated with the bonding temperature of 420.43°C, bonding pressure of 7.70 MPa, holding time of 27.15 min, and surface roughness of 0.10 μm exhibited maximum shear strength and bonding strength of 51.24 and 72.10 MPa, respectively.
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optimising difFusion bonding parameters to maximize the strength of aa6061 aluminium and az31b magnesium alloy joints
Materials & Design, 2012Co-Authors: Joseph M Fernandus, V Balasubramanian, T Senthilkumar, S RajakumarAbstract:The main difficulty when joining magnesium (Mg) and aluminum (Al) alloys by Fusion Welding Process lies in the existence of oxide films and formation of brittle intermetallic in the weld region. However, solid-state Welding Processes such as friction Welding and difFusion bonding are suitable Processes to join these two materials. The difFusion bonding Process parameters such as bonding temperature, bonding pressure, holding time, and surface roughness of the bond specimen play a major role to determine the joint strength. In this investigation, an attempt was made to develop empirical relationships to predict the lap shear strength and bonding strength of difFusion bonded dissimilar joints of AZ61A magnesium and AA6061 aluminum alloys, incorporating the above-mentioned parameters. Response surface methodology (RSM) was applied to optimize the difFusion bonding Process parameters to attain the maximum shear strength and bonding strength of the joint. From this investigation, it is found that the bonds fabricated with the bonding temperature of 420.43°C, bonding pressure of 7.70 MPa, holding time of 27.15 min, and surface roughness of 0.10 μm exhibited maximum shear strength and bonding strength of 51.24 and 72.10 MPa, respectively.
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influence of friction stir Welding Process and tool parameters on strength properties of aa7075 t6 aluminium alloy joints
Materials & Design, 2011Co-Authors: S Rajakumar, C Muralidharan, V BalasubramanianAbstract:Abstract The aircraft aluminium alloys generally present low weldability by traditional Fusion Welding Process. The development of the friction stir Welding has provided an alternative improved way of satisfactorily producing aluminium joints, in a faster and reliable manner. In this present work, the influence of Process and tool parameters on tensile strength properties of AA7075-T 6 joints produced by friction stir Welding was analysed. Square butt joints were fabricated by varying Process parameters and tool parameters. Strength properties of the joints were evaluated and correlated with the microstructure, microhardness of weld nugget. From this investigation it is found that the joint fabricated at a tool rotational speed of 1400 rpm, Welding speed of 60 mm/min, axial force of 8 kN, using the tool with 15 mm shoulder diameter, 5 mm pin diameter, 45 HRc tool hardness yielded higher strength properties compared to other joints.
Suresh D Meshram - One of the best experts on this subject based on the ideXlab platform.
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influence of tool tilt angle on material flow and defect generation in friction stir Welding of aa2219
Defence Science Journal, 2018Co-Authors: Suresh D Meshram, Madhusudhan ReddyAbstract:Heat treatable aluminium alloy AA2219 is widely used for aerospace applications, welded through gas tungsten and gas metal arc Welding Processes. Welds of AA2219 fabricated using a Fusion Welding Process suffers from poor joint properties or Welding defects due to melting and re-solidification. Friction stir Welding (FSW) is a solid-state Welding Process and hence free from any solidification related defects. However, FSW also results in defects which are not related to solidification but due to improper Process parameter selection. One of the important Process parameters, i.e., tool tilt angle plays a critical role in material flow during FSW, controlling the size and location of the defects. Effect of tool tilt angle on material flow and defects in FSW is ambiguous. A study is therefore taken to understand the role of tool tilt angle on FSW defects. Variation in temperature, forces, and torque generated during FSW as a result of different tool tilt angles was found to be responsible for material flow in the weld, controlling the weld defects. An intermediate tool tilt angle (1o-2o) gives weld without microscopic defect in 7 mm thick AA2219 for a given set of other Process parameters. At this tool tilt angle, x-force, and Z- force is balanced with viscosity and the material flow strain rate sufficient for the material to flow and fill internal voids or surface defects in the weld.
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friction stir Welding an alternative to Fusion Welding for better stress corrosion cracking resistance of maraging steel
Journal of Manufacturing Processes, 2017Co-Authors: Archana Paradka, Suresh D Meshram, Madhusudha G Reddy, Sunil PandeyAbstract:Abstract Friction stir Welding (FSW), a solid state Welding Process, is generally used for Welding soft materials like aluminium and magnesium alloys. In this work, maraging steel, an ultra high strength steel, is welded using FSW Process. Major problems associated with Fusion welded maraging steel, i.e segregation of alloying elements and formation of reverted austenite pool, were suppressed by FSW. Slow strain rate stress corrosion characteristic of 18%Ni maraging steel (grade-250) and its weldments, by gas tungsten arc Welding (GTAW) and FSW, has been investigated in air and 3.5% NaCl solution. It was observed that FSW joints demonstrated higher resistance to stress corrosion cracking (SCC) compared to both, base metal and gas tungsten arc weldments. Improved stress corrosion resistance of friction stir weldments was correlated to microstructural differences and residual stress. Fine grain structure, absence of segregation of alloying elements and high compressive residual stress in friction stir weld resulted in better SCC resistance compared to that of Fusion weldment. It is brought out from the present study that FSW Process can be used as an alternative to Fusion Welding Process for better SCC resistance.
N Yadaiah - One of the best experts on this subject based on the ideXlab platform.
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development of egg configuration heat source model in numerical simulation of autogenous Fusion Welding Process
International Journal of Thermal Sciences, 2014Co-Authors: N YadaiahAbstract:The mathematical structure of the heat source models should at least approximately represent the phenomena of real heat source. In Fusion Welding Process, only the surface heat flux fails to realize enhanced heat transfer due to predominant effect of momentum transport of the material within molten pool. The convection in the weld pool can be substituted by apparent volumetric heat source which is unrealistic to define outside the molten pool volume. The key issues to define a decent volumetric heat source are the geometric shape and size, non-symmetric heat density distribution due to moving arc or laser beam. In present work, the egg-configuration volumetric heat source model is proposed to address these issues. The proposed heat source model which is derived from ellipsoid shape provides the nonsymmetry heat energy distribution with less number of model parameters and conserves the continuity in profile during moving heat source problem. The general equation of egg-configuration heat source provides the basis of Gaussian distributed disc, hemispherical, and semi-ellipsoidal volumetric heat source models which can be considered as the special cases of proposed heat source model. A 3D finite element based transient heat transfer analyses is conducted using the proposed heat source model for gas tungsten arc Welding (GTAW) and diode laser Welding Processes. The maximum deviation of 10% in weld pool size estimation is observed as compared to experimental results. The time-temperature history confirms the peak temperatures of 940 K and 1060 K, respectively for GTAW and laser Welding Processes. The amount of the maximum cooling rate predicted for GTAW is 603 K/s which is significantly lower than 11.1 � 10 3 K/s for laser Welding. Overall, the proposed heat source model generalized the
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Numerical simulation of Welding-induced residual stress in Fusion Welding Process using adaptive volumetric heat source
Proceedings of the Institution of Mechanical Engineers Part C: Journal of Mechanical Engineering Science, 2014Co-Authors: Sachin Singh, N Yadaiah, Swarup Bag, Sukhomay PalAbstract:The mechanical properties of a weldment structure are influenced by the level of residual stress generated during Fusion Welding Process. The experimental determination of residual stress is cumbersome and not free from measurement errors. A sophisticated numerical model is relatively easy approach to predict residual stress due to the advancement of high performance computational technology. However, the integration of all Process physics to make a sophisticated numerical model is ever demanding. The present work is motivated in that direction and involves a finite element based numerical model for simulation of Welding-induced residual stresses. A thermal model using adaptive volumetric heat source has been used to estimate temperature distribution. Subsequently, the thermal history is used to perform stress analysis for butt welded plates using three different Fusion Welding Processes. The material behaviour is assumed as elasto-plastic in nature. The calculated results and their trend have been valida...
Sunil Pandey - One of the best experts on this subject based on the ideXlab platform.
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friction stir Welding an alternative to Fusion Welding for better stress corrosion cracking resistance of maraging steel
Journal of Manufacturing Processes, 2017Co-Authors: Archana Paradka, Suresh D Meshram, Madhusudha G Reddy, Sunil PandeyAbstract:Abstract Friction stir Welding (FSW), a solid state Welding Process, is generally used for Welding soft materials like aluminium and magnesium alloys. In this work, maraging steel, an ultra high strength steel, is welded using FSW Process. Major problems associated with Fusion welded maraging steel, i.e segregation of alloying elements and formation of reverted austenite pool, were suppressed by FSW. Slow strain rate stress corrosion characteristic of 18%Ni maraging steel (grade-250) and its weldments, by gas tungsten arc Welding (GTAW) and FSW, has been investigated in air and 3.5% NaCl solution. It was observed that FSW joints demonstrated higher resistance to stress corrosion cracking (SCC) compared to both, base metal and gas tungsten arc weldments. Improved stress corrosion resistance of friction stir weldments was correlated to microstructural differences and residual stress. Fine grain structure, absence of segregation of alloying elements and high compressive residual stress in friction stir weld resulted in better SCC resistance compared to that of Fusion weldment. It is brought out from the present study that FSW Process can be used as an alternative to Fusion Welding Process for better SCC resistance.
Swarup Bag - One of the best experts on this subject based on the ideXlab platform.
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Numerical simulation of Welding-induced residual stress in Fusion Welding Process using adaptive volumetric heat source
Proceedings of the Institution of Mechanical Engineers Part C: Journal of Mechanical Engineering Science, 2014Co-Authors: Sachin Singh, N Yadaiah, Swarup Bag, Sukhomay PalAbstract:The mechanical properties of a weldment structure are influenced by the level of residual stress generated during Fusion Welding Process. The experimental determination of residual stress is cumbersome and not free from measurement errors. A sophisticated numerical model is relatively easy approach to predict residual stress due to the advancement of high performance computational technology. However, the integration of all Process physics to make a sophisticated numerical model is ever demanding. The present work is motivated in that direction and involves a finite element based numerical model for simulation of Welding-induced residual stresses. A thermal model using adaptive volumetric heat source has been used to estimate temperature distribution. Subsequently, the thermal history is used to perform stress analysis for butt welded plates using three different Fusion Welding Processes. The material behaviour is assumed as elasto-plastic in nature. The calculated results and their trend have been valida...
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AN EXPERIMENTAL INVESTIGATION ON FIBER LASER Welding AT CONTROLLED INERT GASATMOSPHERE
2014Co-Authors: Yadaiah Nirsanametla, Swarup Bag, Christ P. Paul, Lalit M. Kukreja, Raja RamannaAbstract:Fiber laser is a desirable heat source for deep-penetration and high-speed Fusion Welding Process due to its noticeable advantages such as high beam quality and high efficiency over other lasers. During Fusion Welding Process, thermo-chemical reactions may take place among surrounding atmosphere particles and molten weld pool at high temperature gradients. The atmosphere particles such as oxygen, hydrogen and nitrogen may become part of final weld joint that severely affects the weld joint quality and weld metal properties. Therefore, the Welding atmosphere and protection of weld pool plays a noticeable role on the quality of the final weld joint. Henceforth, in the present work, fiber laser Welding of austenitic stainless steelhave been investigated in two different ambient atmospheres. Firstly, the experiments are conducted in open atmosphere and in argon ambient atmosphere to study the characteristic difference on weld joint with respect to weld bead size and dimensions, and microstructure formation at different Welding speeds. The experimental investigation specifies that the weld bead dimensions are higher in case of argon atmosphere as compared to open atmosphere. The microstructures of heat affected zone (HAZ) and Fusion zone (FZ) at both atmospheric conditions are analyzed. It is also obvious from the experimental results that the top surface profile is better and weld surface is very clear in case of welds at argon atmosphere as compared to open atmospheric condition.
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EFFICIENT ESTIMATION OF VOLUMETRIC HEAT SOURCE IN Fusion Welding Process SIMULATION
Welding in The World, 2012Co-Authors: Swarup Bag, Degala Venkata Kiran, Arshad Alam SyedAbstract:Mathematical models of heat transfer phenomena in Fusion Welding Process can provide important physical insight on the mechanism of weld pool development, and compute temperature field and final weld dimensions fairly reliably in several Welding systems. In particular, the conduction heat transfer based numerical models are relatively simpler and computationally inexpensive in comparison to the comprehensive heat transfer and fluid flow models although the later can undertake greater physical attributes in weld pool. One significant requirement of the conduction heat transfer based models is the predetermination of a volumetric source term to account for the heat input from the Welding heat source. We present here two efficient approaches to define the volumetric heat source term which do not require a-priori information of the final weld joint dimensions, which has always remained a difficult task. The first approach involves an intrinsic mapping of the heat source geometry with the numerically computed melt pool dimensions within the framework of modeling calculations in an iterative manner and is validated for the prediction of final weld dimensions in autogenous gas tungsten arc welds with butt joint geometry. The other approach involves an analytical estimation of the volumetric source term as function of only the Welding conditions and the initial weld joint geometry and is examined successfully for the prediction of weld pool dimensions and thermal cycles in tandem submerged arc welds with typical groove joint geometry.
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Probing Reliability of Transport Phenomena Based Heat Transfer and Fluid Flow Analysis in Autogeneous Fusion Welding Process
Metallurgical and Materials Transactions A, 2010Co-Authors: Swarup BagAbstract:The transport phenomena based heat transfer and fluid flow calculations in weld pool require a number of input parameters. Arc efficiency, effective thermal conductivity, and viscosity in weld pool are some of these parameters, values of which are rarely known and difficult to assign a priori based on the scientific principles alone. The present work reports a bi-directional three-dimensional (3-D) heat transfer and fluid flow model, which is integrated with a real number based genetic algorithm. The bi-directional feature of the integrated model allows the identification of the values of a required set of uncertain model input parameters and, next, the design of Process parameters to achieve a target weld pool dimension. The computed values are validated with measured results in linear gas-tungsten-arc (GTA) weld samples. Furthermore, a novel methodology to estimate the overall reliability of the computed solutions is also presented.
