Testing of magnetic pulse welded joints - destructive and non-destructive methods

摘要

Electromagnetic pulse welding is an innovative technology suitable for joining various similar and dissimilar tube and sheet metal parts including dissimilar material combinations, which are difficult to join by conventional, i.e. thermal welding methods. In case of proper choice of process parameters, a high joint quality can be achieved. In literature this is often demonstrated by failure in the base material during destructive testing. However, no standard testing procedures for magnetic pulse welded joints have been agreed on and thus industrial implementation is severely complicated. Specifically, investigations regarding non-destructive testing are rarely available. The paper evaluates different testing and characterization methods. Specifically, metallographic analysis and lap shear tests are taken into consideration. Finally, Laser UltraSound (LUS) is presented as a new alternative for characterizing magnetic pulse welded joints. The technique is based on measuring laser ultrasound waves which are either transmitted through or reflected by the weld seam. A comparison of the results to those of the more established destructive testing methods shows, that LUS measurements absolutely allow qualitative and quantitative conclusions regarding weld quality. Due to high automation potential, the method is a promising alternative for quality control in industrial manufacturing.