Magnetic Pulse Welding of Two Dissimilar Materials with Various Combinations Adopted in Nuclear Applications

Abstract

In this paper the joining of two dissimilar metals as Al-SS, Al-Cu and SS-Cu were studied. Commonly, MPW is considered as a non-melting process. Magnetic Pulse machine which is belong to Non-conventional technique instead of conventional technique. Magnetic Pulse Welding (MPW) is a joining process in which lap joint surfaces of cylindrical shape metals, such as pipes and tubes, are welded by impact, using electromagnetic forces. MPW is classified in the group of solid-state bonding processes together with Explosive Welding (EXW). The technique has become an unique and acknowledged welding process because it enables to join similar, as well as dissimilar metals, which is very difficult to weld by traditional methods such as GTAW or EBW due differences in melting points etc. MPW process is very fast, produces no Heat Affected Zone (HAZ) and may be performed without filler metals and protective gases. Nevertheless, it was detected a very thin film (10 to 50 μm) of two welded metals in the form of intermetallic phases, in which melting and solidification processes took place. These inter-metallic phases significantly affect the mechanical properties of the joint. The diffusion of elements in the intermetallic phase was studied for the pattern and the composition of the blended metals and formation of pores etc. The interface typically presents a wavy pattern and mutual diffusion of elements happens in the transition zone. The transition zone is composed of elements intermetallics, micro cracks and micro pores as expected in our study. The effect of the parameters on the morphology, configuration and structure of the interface has been thoroughly studied. The weld interface composition, structure and morphology were studied by optical and Scanning Electron Microscopy (SEM). Energy-Dispersive Spectrometry (EDS) was used in order to evaluate the local distribution of alloying elements at the joint interface and its vicinity and also Nano-hardness tests were performed across the bonding zone at regular increments. The results of the joints were analysed for process parameters and based on the result, the process parameters has to be reviewed accordingly to yield best interface weld results.