Magnetic Pulse Welding for Dissimilar and Similar Materials

The Magnetic Pulse Welding (MPW) process, a cold solid state welding process, is an industrial process, operating at several high volume manufacturing facilities. MPW is accomplished by the magnetically driven, high velocity, oblique angle, impact of two metal surfaces. At impact, the surfaces (which will always have some level of oxidation) are stripped off and ejected by the closing angle of impact. The surfaces which are then metallurgically pure, are pressed into intimate contact by the magnetic pressure, allowing valence electron sharing and atomic-level bonding. This process has been demonstrated in the joining of tubular configurations of a variety of metals and alloys [1],[2],[3]. Product designers are frequently constrained by the restrictions of traditional joining technologies, which place certain limitations on the type of joint, the materials that can be joined and the quality of the joint. Solid state welding allows manufacturers to significantly improve their product designs and production results by enabling both dissimilar and similar materials to be welded together, thus providing the opportunity to use lighter and stronger material combinations. Magnetic pulse welding is a fast, noncontact and clean solid state welding process. A review of the main elements of the process is presented here along with typical quality testing results and some applications

Magnetic Pulse Acceleration

The present work is dedicated to describing works in the spheres of simulation, calculation, and experimental results of acceleration by pulsed electromagnetic forces where strain rates of 10,000 - 50,000 s^(-1) are common. The goal is to design a multidisciplinary model that will overcome the shortcomings of normal simulation methods that solve the EM field and then apply the solution in a mechanical analysis. Improved numeric models for virtual simulation of magnetic pulse processes are detailed, along with the pulse-power equipment and a special measurement system developed to verify these models and to determine material property data. These measure both radial velocity and axial speed (collision-point progression) for tube forming and / or welding processes, while logging the pulse current and magnetic field. The results show good a correlation between test and multiphysics model and provide valuable new insights, as well as an extraction of critical parameters by way of a comparison between calculated and measured data for materials such as aluminum alloys, copper, and steel

Pulsed Power Forming

R&D and application work in the sphere of Pulsed Power Forming (PPF) is well known and has been documented since the 1960's, along with its advantages. Pulsed Power Forming applications, which have been developed at Pulsar Ltd over the last decade, are described in this paper. Special equipment and tools for forming have been designed, developed, and manufactured, utilising pulsed magnetic fields. Theoretical and experimental research has been carried out to determine the magnetic field distribution in certain types of solenoids for diameters up to 600 mm. The software for mechanical pressure simulation and calculation has been carried out. Research and application of forming by electrical discharge into liquid medium have been carried out with higher deformation than it has been attained by the classic processes. Flat forming, cutting, and/or perforating of very thin materials (with thicknesses in the range of 0,1 up to 0,3 mm), such as aluminium, steel, stainless steel, nickel alloys, etc., have been made by applying high magnetic field with elastic medium. In addition, forming and cutting of a steel tube with ~100 mm OD and a wall thickness up to 3 mm have been executed using direct high pulse magnetic field action. Aluminium tubes with OD ~100 mm and a wall thickness less than 0,5 mm have also been similarly processed

3D Impacts Modeling of the Magnetic Pulse Welding Process and Comparison to Experimental Data

Magnetic Pulse Welding (MPW) is a solid state (cold) welding process known to present several advantages. When properly designed, such an assembly is stronger than the weakest base material even for multi-material joining. These high quality welds are due to an almost inexistent Heat Affected Zone which is not the case with fusion welding solutions. Another advantage is a welding time that is under a millisecond. In order to define the MPW parameters (mainly geometry, current and frequency), recent developments have made it possible to adapt welding windows from the Explosive Welding (EXW) for use in MPW. Until now, these welding windows have been simulated only in 2D geometries showing how the impact angle and the radial velocities progress in a welding window. The aim of this paper is to present our most recent development, which builds on this analysis to develop a 3D model in order to deal for example with local planar MPW. Simulation results will be presented and then compared to experimental data for a multimaterial join case