An investigation of fusion zone microstructures in electron beam welding of copper–stainless steel.pdf

Materials Science and Engineering A 424 (2006) 163–173 An investigation of fusion zone microstructures in electron beam welding of copper–stainless steel I. Magnabosco a, P. Ferro a,?, F. Bonollo a, L. Arnberg b a Department of Management and Engineering, University of Padova, Stradella S. Nicola, 3 I-36100 Vicenza, Italy b Department of Materials Science and Engineering, Norwegian University of Science and Technology, 7491, Trondheim, Norway Received 1 October 2005; received in revised form 1 February 2006; accepted 1 March 2006 Abstract The article presents a study of three different welded joints produced by electron beam welding dissimilar materials. The junctions were obtained between copper plates and three different austenitic stainless steel plates. Different welding parameters were used according to the different thicknesses of the samples. Morphological, microstructural and mechanical (micro-hardness test) analyses of the weld bead were carried out. The results showed complex heterogeneous fusion zone microstructures characterized both by rapid cooling and poor mixing of the materials which contain main elements which are mutually insoluble. Some defects such as porosity and microfissures were also found. They are mainly d ? K 1 t b o o t i i o o w c t m m w t o 0 due to the process and geometry parameters. 2006 Elsevier B.V. All rights reserved. eywords: Dissimilar metal welding; Electron beam welding; Fusion zone microstructure; Stainless steels; Copper . Introduction Welding of dissimilar metals has been the object of inves- igations for many years; their growing importance is justified y their technical and economic potentials. Dissimilar metals r alloys are welded in order to gain flexibility but this practice ften yields problems that negatively affect the performance of he weld. A question of primary importance is the evaluation of the ntrinsic properties of the materials to use in a dissimilar weld- ng. Many researchers [1–7] studied the effects of