Place: BAM Federal Institute for Material Research and Testing, Berlin, Germany
Pedro Dolabella Portella, Abteilung V Werkstofftechnik, Bundesanstalt für Materialforschung und –prüfung, Berlin, Germany
The history of BAM can be traced back to the year 1871 with the foundation of the Royal Institution for Mechanical Testing (Königliche Mechanisch-Technische Versuchsanstalt) in Berlin. In its first years the activities of this institution were mainly determined by personalities as August Wöhler, Adolf Martens and Emil Heyn. A central task was from the begin on the evaluation of machine elements and components from the materials point of view. The first part of our presentation will be an overview of our activities in the area of the single crystalline nickel base superalloys. These materials have a relatively simple microstructure, which allows a thorough description of the mechanisms of deformation. On the other hand their intrinsic anisotropy leads to difficulties in measuring the deformation and interpreting the results. On the basis of the results of mechanical tests (creep, LCF, TMF) and of the description of the accompanying microstructural changes we will present and discuss an anisotropic viscoplastic model. In the second part of our presentation we will describe the usual procedure for the analysis of a technical failure: The capsizing of the MV Estonia in September 1994 was the largest catastrophe in the ocean shipping after the World War II. Non government organizations carried on independent investigations which lead to the suspicion of a terror act. Explosives in the front part of the boat would be responsible for the tragedy. Under huge efforts these groups were able to recover a small piece of the ship hull lying in the bottom of the Baltic Sea. BAM was asked to analyze this fragment and determine the origin of the fracture surface. Our results clearly exclude an explosion in the neighbourhood of this fragment.