Magnetically Impelled Arc Butt Research Articles

Simulation Study of Critical Aspects of MIAB Welding for Analysis of Potential Factors Governing the Performance of Weld Formation

Magnetically Impelled Arc Butt (MIAB) welding, is a solid-state welding technique. The magnetic system of this technique is pivotal for the generation of the Lorentz force, which impels an arc to rotate along the periphery of the weld tubes and thus facilitates the heating of faying surfaces. The magnetic arrangement and the arc dynamics significantly impact the effectiveness of the welding process, eventually dictating the efficiency. This study case investigates the impact of the magnetic arrangement on the arc rotation and possible factors that cause irregularities in the (MIAB) welding through COMSOL simulation. The COMSOL simulation has served as a powerful tool to comprehensively analyse various arc dynamics and magnetic systems and extrapolate the observations to analyse the arc dynamics and magnetic systems involved in MIAB welding. By employing simulation studies, the research aims to unravel critical insights for an efficient design of the MIAB welding system. This work includes a study of the effect of magnetic forces on arc dynamics using various models and attempts to develop an analogy to the MIAB welding process. This is further utilized to explain the process variations in the form of arc displacement, electric potential distribution, and the possibility of self-demagnetization of AlNiCo magnets. Thus, it provides a foundation for advancing the technological aspects of MIAB welding to overcome the limitations and irregularities. This research is instrumental in enhancing the understanding of magnetic interactions involved in the MIAB process, which can further pave the way for improved welding machine designs and consequently, enable research on these lines that can help in establishing an optimized parametric window.

Critical Review on Magnetically Impelled Arc Butt Welding: Challenges, Perspectives and Industrial Applications.

Magnetically Impelled Arc Butt (MIAB) welding is a cutting-edge joining method that replaces the conventional welding procedures such as resistance, friction, flash and butt welding. It is a solid-state process that uses a rotating arc to heat up the butt ends of tubes, being followed by a forging process that completes the joining of the workpieces The magnetic flux density and the current interact to develop the Lorentz force that impels the arc along the faying surfaces. This process is found to produce high tensile strength and defect-free welds in ferrous materials and for this reason, it is predominantly employed in automobile applications for joining metallic tubes. Also, this joining procedure can be applied in the fabrication of boilers, heat exchangers, furnace piping in petrochemical industry and other safety-critical high-pressure machinery parts. The MIAB method has several advantages such as a shorter welding cycle, lower input energy requirement and lower loss of material. Compared to other solid-state welding processes, the MIAB welding has an important advantage in terms of cost-efficient welds with better control and reliability. Moreover, there are researchers who have investigated the joining of non-ferrous dissimilar materials using this welding procedure. The studies have been focused on process parametric analysis that involves optimizing and forecasting the magnetic field and thermal profile distribution. This review article provides competitive insights into various design features, computational methods, tests and material characterization, technical issues and workarounds, as well as automation aspects related to the MIAB-welding process. This work will prove to be a quick reference for researchers, useful to identify the research gaps and conflicting ideas that can be further explored for advancements in joining the similar and dissimilar materials.

Non-Destructive Testing of Magnetically Impelled Arc Butt Welding of Mild Steel Tubes

This paper presents the results of Non-Destructive Testing on Magnetically Impelled Arc Butt (MIAB) welded mild steel tubes of 27mm OD and 1.5mm thickness. As part of this work, the tests covered were radiography, liquid penetrant, and magnetic particle testing. The testing results indicate that porosity, penetration levels and the defects found are within acceptable limits as per standard. For this experimental work, the selection of parameters was based on trial and error adopted in preliminary trials. The irregularities found in the non-destructive testing samples have enabled the fine-tuning of process parameters. The optimum values of hydraulic pressure, weld time and weld current are assessed to be 30-35bar, 5.5s and 150 A, respectively 270 A for this dimension of tubes. This work focuses on the experimental observations of MIAB welding and Non-destructive testing results for MS tubes of the selected dimension, which have not been reported in the existing literature. The achieved input forms the database for the parametric study of this process. The optimum parametric ranges obtained from the results can be extrapolated to be used for joining tubes of different dimensions and can also form the inputs for reaching parameter and response dependency equations.

Welding of Low Carbon Steel Tubes Using Magnetically Impelled Arc Butt Welding: Experimental Investigation and Characterization

Magnetically impelled arc butt (MIAB) welding is a solid-state technique of welding that utilizes the heating effect of a high-speed rotating arc for the formation of the weld. The process exhibits lower time and power consumption compared to conventional solid-state processes for tube–tube joining. However, the available research reports on MIAB welding of Mild Steel (MS)1018 are still inadequate and lack the details required for extending the applications of this process. Hence, this study was undertaken to investigate MIAB welding for MS 1018 tubes. Experimental investigations were performed on a specifically designed and newly fabricated MIAB welding machine. The experimental trials involved varying the process parameters and understanding their influence on joint strength and other weld characteristics. Microstructure of the MIAB weld consisted of acicular ferrite which differed from the microstructure of the heat-affected zone. These trials helped to arrive at the optimum parametric window that specified the ranges of key parameters viz. welding current, upset current, and welding time to yield an efficient weld. Chemical analysis of the weld indicated the absence of inter-metallics. MIAB welding of MS1018 showed greater strength and integrity at the joint when optimum ranges of the process parameters were maintained, and is feasible for deployment as economizer coils in boilers, pressure part tubes, and automobile tubular component joining applications.

Study on notch tensile properties of Magnetically Impelled Arc Butt (MIAB) welded carbon steel tubes

Magnetically Impelled Arc Butt (MIAB) welding is a pressure welding process that uses the circumferential rotating arc to cause uniform heating of the faying surfaces. In this work, notched tensile testing of MIAB welded Carbon steel was carried out to determine the notch sensitivity of Thermo-Mechanically Affected Zones (TMAZ) and to compare the notch tensile property of these zones with the base metal property. In MIAB welding, after sufficient melting of the faying surface, a short pulse of high current is applied to expel the molten metal and impurities from the interface before welding. Insufficient expulsion and formation of Light Band (LB) zone at weld interface resulted in lower Notch Tensile Strength (NTS). Incomplete expulsion with lower upset current at the weld interface contributes to lower Normalized Notch Strength Ratio. Instead higher upset current contributed to higher NTS due to complete expulsion and stronger acicular ferrite formation. Other TMAZs away from the weld interface showed higher notch tensile strength with Notch Strength Ratio (NSR) and Normalized Notch Tensile Strength Ratio (NTSN) greater than unity.

Influence of arc duration on microstructure and tensile behavior of magnetically impelled arc butt welded AISI 409 ferritic stainless steel tubes

Magnetically impelled arc butt (MIAB) welding has been the focus of several industries to weld metals in tubular form. 4 mm thick AISI 409 ferritic stainless steel tubes were joined effectively using MIAB welding. The arc duration was varied (4s–8s with an increment of 1s) during welding and all other process parameters such as arc rotation current, upset current, upset time, upset pressure and initial gap were maintained at a constant value. Several microscopic techniques were used to study the microstructure evolution in the joint region. The increase in arc duration pumped more heat energy during joining and increased the size of the weld zone and the axial shortening. The weld zone exhibited a typical forged structure which was affected by heat and mechanical force and is known as TMAZ. The grain size was continuously refined from base metal towards the weld center. The changes in grain size allowed dividing TMAZ into three regions. The welding cycle did not cause any grain growth to produce a heat affected zone (HAZ) similar to fusion welding processes. The increase in arc duration increased the grain size at the weld center. The ferritic structure did not transform into other structures during welding. There was a remarkable increase in the hardness of TMAZ compared to base metal. The strengthening was ascribed to the formation of strain fields in large quantities due to upsetting. Variation in arc duration remarkably influenced the tensile strength and the fracture location. The choice of the arc duration is important to produce sound joints.

Evaluation of the microstructural and mechanical properties of ductile cast iron and alloy steel dissimilar materials welded by magnetically impelled arc butt

The combined use of ductile cast iron and alloy steel is beneficial, however, this technique causes some difficulties in welding due to the different properties of these two materials. In the present work, magnetically impelled arc butt (MIAB) welding a solid-state joining process, was employed to weld GGG40 ductile cast iron tube and an E355 + N alloy steel tube (each one had a thickness of 6 mm). The microstructure and mechanical properties of the resultant joints along different positions of the weld tube were systematically investigated. The heating during MIAB welding was non-uniform, causing significant changes in the microstructure, microhardness, and tensile stress of the welds. The maximum hardness of the welds (482 HV) was much higher than that of the base metal. The average (334.4 MPa) and maximum tensile strengths (382.4 MPa) of the welds were 83.6% and 95.6% of those of the base metal, respectively. These results show that MIAB is an effective method for welding ductile cast iron/alloy steel dissimilar materials.

Notch tensile properties of Magnetically Impelled Arc Butt (MIAB) welded T11 steel tubes

The Magnetically Impelled Arc Butt (MIAB) welding process uses a rotating arc as its heat source and is known as an efficient method for tube welding. Interaction of external magnetic field and induced magnetic flux results in the creation of Lorentz force along peripheral edges of tubes. The circumferential arc rotation helps in the uniform heating of faying surfaces. After sufficient melting, faying surfaces are pressed against each other for weld formation. This paper aims at studying the notch tensile properties of T11 tubes welded by MIAB welding. In MIAB welded T11 steel tubes various Thermo-Mechanically Affected Zones (TMAZ) are formed as an effect of heat and pressure during welding. Tensile properties of all these TMAZs are different due to varying microstructures. Therefore notched tension testing was carried out to compare the properties of various zones in welded T11 tubes. All TMAZs show higher notch ductility with Notch Strength Ratio (NSR) greater than one. In comparison to the base metal, all TMAZs except TMAZ III display no loss in notch strength. The presence of granular bainite in TMAZ III causes lower notch strength with a Normalized Notch strength (NTSN) ratio less than unity.

Exploration of magnetically impelled arc butt welded SA210GrA tubes for boiler applications

Abstract Magnetically impelled arc butt (MIAB) welding is a pressure welding process used for joining of pipes and tubes with an external magnetic field affecting arc rotation along the tube circumference. In this work, MIAB welding of SA210GrA tubes were carried out to study the microstructure of weldedments. The effect of arc current on the weld interface is also detailed and is found to be defect free at higher values of arc currents. The results reveal that MIAB welded specimens shows superior structural property correlation for high pressure applications with an added benefit of improved productivity at lower cost. The study will enable the use of MIAB welding for high pressure applications in power and defence sectors.

Формирование соединений при сварке толстостенных труб из высокопрочных сталей дугой, управляемой магнитным полем

Формирование соединений при сварке толстостенных труб из высокопрочных сталей дугой, управляемой магнитным полем

Light Band Zone Formation and its Influence on Properties of Magnetically Impelled Arc Butt (MIAB) Welded Carbon Steel Tubes

Magnetically Impelled Arc Butt (MIAB) welding is a solid state welding process especially used in circumferential butt welding of tubes in which heat is generated prior to upsetting by an electric arc moving along the peripheral edges of the weldment with the aid of an external magnetic field. This paper aims at studying the formation of Light Band (LB) zone and its effect on the weld properties of MIAB welding of carbon steel tubes. A detailed microstructural analysis has been carried out to understand the microstructural transformations taking place in Thermo-Mechanically Affected Zone leading to formation of LB zone. Welded samples show better tensile properties with higher upset current as it eliminates LB zone formation at weld interface. For lower upset current, width of the LB zone increases with increase in arc rotation current resulting in lower weld tensile strength.

Experimental- and numerical-based studies for magnetically impelled arc butt welding of T11 chromium alloy tubes

Magnetically impelled arc butt (MIAB) welding is a pressure welding process used for joining of pipes and tubes with an external magnetic field affecting arc rotation along the tube circumference. Past studies based on experiments and finite element analysis (FEA) suggested that the weld quality can be significantly improved by proper adjustment of its input parameters such as current, voltage, flux density, etc. Experiments are useful for understanding the physics behind the process, but the quantification and optimization of the MIAB process needs a thorough numerical investigation. Therefore, the present work presents a combined experimental and numerical study for investigating the arc speed indicator of the T11 grade chromium alloy tubes of the MIAB process. Firstly, experiments on the MIAB process are conducted, and the arc speed is measured based on the four inputs (welding current, welding voltage, magnetic coil current, and voltage). This is followed by introduction of a numerical approach of multi-gene genetic programming (MGGP) to formulate a functional relationship between arc speed and the four design variables. The statistical error metrics based on the square of correlation coefficient, relative error (%), and root mean square were used to validate the model performance against the experimental data. The proposed model can be utilized to select the best combination of input variables to optimize the arc speed, which has a vital role in governing the weld quality. In addition, 2-D analysis conducted reveals that the welding current influence the arc speed of the clay the most followed by coil current and coil voltage.

Characterization of magnetically impelled arc butt welded T11 tubes for high pressure applications

Abstract Magnetically impelled arc butt (MIAB) welding is a pressure welding process used for joining of pipes and tubes with an external magnetic field affecting arc rotation along the tube circumference. In this work, MIAB welding of low alloy steel (T11) tubes were carried out to study the microstructural changes occurring in thermo-mechanically affected zone (TMAZ). To qualify the process for the welding applications where pressure could be up to 300 bar, the MIAB welds are studied with variations of arc current and arc rotation time. It is found that TMAZ shows higher hardness than that in base metal and displays higher weld tensile strength and ductility due to bainitic transformation. The effect of arc current on the weld interface is also detailed and is found to be defect free at higher values of arc currents. The results reveal that MIAB welded samples exhibits good structural property correlation for high pressure applications with an added benefit of enhanced productivity at lower cost. The study will enable the use of MIAB welding for high pressure applications in power and defence sectors.

Effect of Upset Current in Magnetically Impelled Arc Butt (MIAB) Welding of Carbon Steel Tubes

Magnetically Impelled Arc Butt (MIAB) welding is an unique forge welding process in which an arc is drawn in the gap between the two tubes to be welded in order to raise them to a high temperature to allow forging to form a solid state weld. This paper presents the investigations carried out on MIAB welding trials of carbon steel tubes with varying upset current. Upset current is the short pulse of high current applied prior to upset. It plays a significant role in expulsion of molten metal and impurity from weld interface. This study aims at studying the effect of upset current on weld properties. Carbon steel tubes of SA-210 Grade A have been chosen with outside diameter of 44 mm and thickness of 4.5 mm. Mechanical and microstructural characterization of MIAB weldments was carried out. Good correlation exists between the mechanical properties/microstructure and upset current. Lower upset current has detrimental effect on weld tensile strength due to incomplete expulsion of decarburized zone.

Strength assessment using destructive testing on MIAB welded alloy steel tubes and subsequent techno-economical evaluation

In this study, an attempt is being made to determine the feasibility of Magnetically Impelled Arc Butt (MIAB) welding process for joining alloy steel tubes in pressure parts. In view of this, a specially made state of art MIAB welding unit (MD1) available at WRI, BHEL, Tiruchirappalli has been employed and adequate number of welding trials is conducted to weld alloy steel tubes of 6–7mm thickness for boiler applications. The combination of a set of values provided as input is varied for each trial. The welding current and the welding time are divided into three and four stages respectively. For each trial, either the current in stage II is varied or the time for stage III is varied while maintaining the other input parameters constant. These trials are carried out mainly to develop an optimum window (working range) for the process parameters. Further, the strength of MIAB welded specimens are examined by subjecting the welded specimens to various destructive tests. It is observed that the weld region is stronger than the base metal in most of the cases.In the next part of the study, the characteristics of MIAB welded joints for T11 steel tubes are compared with those using flash butt welding and induction pressure welding that is presently employed for alloy steel tube joining in pressure parts. It is found that the manufacturing time and incurred cost per weld drastically reduces while simultaneously increasing the productivity. Hence, the feasibility of MIAB welding process for pressure part is established.

MIAB welding of alloy steel tubes in pressure parts: Metallurgical characterization and non destructive testing

In this research, a pivotal attempt is being made to determine the feasibility of welding alloy steel tubes in pressure parts by employing Magnetically Impelled Arc Butt (MIAB) welding process. In view of this, a specially made state of art MIAB welding unit (MD1) available at WRI, BHEL, Trichy has been employed and adequate number of welding trials are conducted to weld alloy steel tubes of 6–7mm thickness for boiler applications. This paper presents a brief description of various non destructive tests carried out on the MIAB welded joints. Radiography test is performed on the welded specimen under the non destructive tests. Further, metallographic examinations [micrograph, macrograph and SEM] were carried out on the welded specimens. Finally, X-rd examination is performed on the MIAB welded specimens to observe the strain developed at the welded joint and the chemical composition of the weld and the base metal. There are no test standards available for carrying out tests specifically on MIAB welded joints. Hence, the test standards specified for welded tube specimens with solid state welding process (flash butt welding) are adopted for the tests on MIAB welded specimens to assess the quality and strength. It is observed that MIAB has several advantages in terms of its metallurgical integrity, quality and strength.

Feasibility of Magnetically Impelled Arc Butt (MIAB) Welding of High-Thickness Tubes for Pressure Parts

Magnetically impelled arc butt (MIAB) welding is a solid phase pressure welding process similar to flash-butt welding, but it uses a magnetic field to rapidly spin the arc. The spinning arc provides a more consistent interior and exterior weld flash than typically seen on the flash-butt upset areas. MIAB welding process is presently being employed for welding tubular sections in automobile industries in various parts of United Kingdom and Germany. However, there are no details reported in available literatures on application of MIAB welding process for pressure parts. Hence, in this study, a pivotal attempt is being made to employ MIAB welding process to weld carbon steel tubes (51 mm and 44 mm outer diameter) and (5-6 mm thick) in economizer coils of pressure vessel. Several trials are conducted to create an optimal parameter window for MIAB welding process by varying the different input parameters. Further, mechanical testing and metallurgical characterization are carried out on the MIAB-welded specimen to evaluate its strength and to assess the weld integrity. The results of the experiment emphasized that the MIAB-welded joints exhibited high strength and good weld integrity.

Technological windows for MIAB welding of tubes featuring original longitudinal magnetization system with peripheral solenoids

This paper presents the performances of an original longitudinal magnetization system, designed to assure the magnetic flux concentration on the tube wall. This magnetization system is made of several small peripheral solenoids disposed around each tube, parallel to the tube axis, and was used to investigate the interaction between the arc and the magnetic field in case of MIAB (Magnetically Impelled Arc Butt) welding of low carbon steel thin-walled tubes. The main research objective was the development of process parametrical windows for assuring qualitative joint achievement. Macro- and micro-structural analysis accompanies the hardness tests made on corresponding welded samples, demonstrating the operational process maps in producing sound MIAB joints. The paper also discusses the process main stages based on corresponding images resulting from process monitoring, from arc initiation to the emergence of molten metal when upsetting starts and the weld is formed.

Simulation of Magnetic Flux Distribution for Magnetically Impelled Arc Butt Welding of Steel Tubes

This paper proposes a 3‐Dimensional Finite Element Model (FEM) for the simulation of magnetic flux distribution in a Magnetically Impelled Arc Butt (MIAB) welding process. The electromagnetic force responsible for the arc rotation in MIAB welding process is governed by the magnetic flux density in the gap, the arc current and the arc length (gap size). To be precise the radial magnetic flux density is a critical factor in arc rotation and weld quality. The aim of this study is to explore the interdependence of the magnetic flux density and the existing current in the coils using finite element code ANSYS. The results of this analysis are verified with the available experimental data for steel pipes (outer dia 50mm and 2mm thickness). The results of the numerical simulation emphasize that the magnetic flux density in the gap between the pipes is proportional to the exciting current.

Development of a MIAB welding module and experimental analysis of rotational behavior of arc—simulation of electromagnetic force distribution during MIAB welding of steel pipes using finite element analysis

Magnetically impelled arc butt (MIAB) welding is a unique forge welding process in which an arc is drawn in the gap between the two tubes to be welded in order to raise them to a high temperature to allow forging to form a solid-state weld. In this case, the arc is rotated with a high speed around the weld line by an electromagnetic force resulting from the interaction of the magnetic field and the arc current. This paper presents the details of the results and the conclusions of the experimental trials conducted on the MIAB module designed and developed based on the principle. Further, nonlinear electromagnetic analysis has been performed to determine the magnetic field and electromagnetic force distribution in MIAB process using finite element package ANSYS. Typical results of this analysis pertaining to magnetic field are compared with the experimental data for steel tubes (outer diameter 47 mm and thickness of 2 mm). It is observed that the results from finite element analysis and the experimental trials are in excellent agreement. The proposed three-dimensional finite element method model for electromagnetic force distribution facilitates comprehensive understanding of the arc rotation process in MIAB welding.