Effect of beam oscillation on electron beam welding of copper with AISI-304 stainless steel

The quality of dissimilar weld joint between copper and stainless steel (SS) plates using electron beam welding with and without beam oscillation was evaluated through microstructural analysis, hardness, tensile, bend and impact tests. Microstructural analysis as well as quantitative elemental analyses demonstrated that improved mixing of copper with SS in the fusion zone could be achieved by an oscillating beam of optimum oscillation diameter. Although the tensile properties at room temperature did not vary much between the welds; high temperature measurements exhibited significant difference between them. Welds made with beam oscillation having an optimum oscillation diameter demonstrated significant increase in impact strength as well as percentage elongation compared to joints made without beam oscillation. Increased beam oscillation beyond optimum oscillation diameter was found to be detrimental promoting segregation of copper in the weld zone exhibiting deteriorated mechanical properties. A hypothesis has been put forward for better mixing during welding with beam oscillation.