Influence of Process Parameters, Surface Topography and Corrosion Condition on the Fatigue Behavior of Steel/Aluminum Hybrid Joints Produced by Magnetic Pulse Welding

Abstract

In this study, magnetic pulse welded steel/aluminum hybrid joints are investigated with the aim of optimizing the process parameters regarding the fatigue behavior. Changes in discharge current, acceleration distance, welding geometry as well as influences of surface topography and corrosion, are examined regarding fatigue life and damage mechanisms. Instrumented multiple amplitude tests combined with constant amplitude tests are carried out for assessing structure-property-relations in a resource-efficient manner. Stress-induced change in strain and alternating current potential drop measurement are well suited for reliable detection of damage initiation and estimation of the fatigue limit. Results reveal that the fatigue properties primarily depend on the imperfections of the weld seam, which are affected mostly by the discharge current and the surface topography. Corrosion shows to be a relevant factor since it decreases fatigue performance. Suitable process parameters are achieved when the fatigue strength of the weld seam lies above the weaker hybrid joint (aluminum). For S235JR and EN AW1050A-H14 (Al99.5) a suitable discharge current was found to be 349 kA at an acceleration distance of 1.5 mm.