1783 Magnetic flux distribution modelling of magnetically-impelled arc butt-welding of steel tubes using finite-element analysis S Arungalai Vendan 1∗ , S Manoharan 2 , G Buvanashekaran 2 , and C Nagamani 1 1 Department of Electrical and Electronics Engineering, National Institute of Technology, Tiruchirappalli, Tamil Nadu, India 2 Welding Research Institute, BHEL, Tiruchirappalli, Tamil Nadu, India The manuscript was received on 26 January 2008 and was accepted after revision for publication on 24 April 2008. DOI: 10.1243/09544062JMES1025 Abstract: Magnetically-impelled arc butt-welding (MIAB) is a pressure-welding process. In this process, heat is generated prior to forging by an arc created between two clamped and aligned tubes. This arc rapidly rotates along the peripheral edges of the tubes to be welded due to the electromagnetic force resulting from the interaction of the arc current and the magnetic field in the gap. To be precise, the magnetic flux density is the significant parameter that governs the arc rotation and the weld quality. This paper presents a three-dimensional finite-element model to determine the magnetic flux density distribution in the MIAB welding process. The objective of this study is to perform a non-linear electromagnetic analysis using the finite-element pack- age ANSYS, and to explore the interdependence of MIAB welding parameters such as gap size, exciting current in the coil, and coil position from the weld centre, which influence the electro- magnetic force generated in the welding process and weld quality. The results of this analysis are verified with the available experimental data for steel tubes (outer diameter 50 mm and thickness 2 mm). The results obtained using finite-element analysis establish that the magnetic flux density distribution in the gap increases with increasing exciting current and decreasing gap size and coil position from the weld centre. Keywords: MIAB welding, flux distribution, finite-element analysis, steel tube 1 INTRODUCTION Magnetically-impelled arc butt-welding (MIAB) uti- lizes forging to produce the finished weld. It is clas- sified under the electric arc welding process, since the energy source for producing heat for melting is sup- plied by the electric arc, even though pressure from forging is essential to complete the welding. Thus, it is a fusion pressure welding process. In the MIAB weld- ing process, an arc is generated in the gap between the two ends of the tube, and is made to rotate along the peripheral edges of these tubes due to the inter- action of the arc current with an externally applied ∗ Corresponding author: Department of Electrical and Electron- ics Engineering, National Institute of Technology, Tiruchirappalli, Tamil Nadu 620015, India. email: arungalaisv@yahoo.co.in magnetic field. After the arc heats up the edges of the tubes to cause localized melting and adjacent soft- ening in the heat-affected zone (HAZ), the parts are forged together. The MIAB welding process is well established in Ger- many, United Kingdom, and Ukraine. In general, this welding process is adopted in the automobile indus- try for the fabrication of tubular section butt welds. Tubes can have circular or non-circular cross-sections with wall thickness ranging from 0.7 to 6 mm. Steels as well as aluminum alloys have been welded successfully in mass production, producing welds with excellent quality. From the available literature, previous research works on MIAB welding is discussed now in brief. Edson [1] focused on the application of MIAB weld- ing. This technique has been utilized mainly in the European automobile industry to weld carbon and JMES1025 © IMechE 2008 Proc. IMechE Vol. 222 Part C: J. Mechanical Engineering Science