Magnetic impulse welding of aluminium tube and copper tube with various core materials

Magnetic impulse welding is a joining process in which lap joint surfaces of cylindrical materials, such as, pipes, are pressure welded using electromagnetic force. This process causes little decline in material strength due to thermal effects and little formation of brittle intermetallic compounds compared with general welding processes; the process is suitable for joining thin walled pipes of dissimilar metals and avoids the need for any binder for dissimilar metal joining. In addition, no special pressurising equipment is required and, because it is a simple process with the capability of joining within a short timescale, this process is expected to be employed as a technique which can be applied for on site pipework operations. In this study trials were carried out on magnetic impulse welding of aluminium pipes or copper pipes with similar/dissimilar metal cores with the aim of ensuring that this technique can be practically applied to pipework joints used in refrigerators and air conditioning systems. In particular, specimens without taper were employed, in order to simplify machining of the cores prior to welding; an investigation into the welding conditions was carried out so that the pressure resistance and the weld strength required at pipework joints could be obtained from consideration of plastic deformation of the cores and whether the weld interfaces had been degreased. Materials include 1050, C1020, 1100, C1100 alloys and C3604 brass and SS400 steel.