Lehrstuhl für Fertigungstechnologie, Universität Erlangen-Nürnberg

Laser forming of aluminium alloys - influencing of microstructure and mechanical properties



Datum: 28.05.2001


Author


Reporter

  • Prof. Dr.-Ing. M. Geiger
  • Prof. Dr.-Ing. Dr. h.c. mult. R. Kopp, RWTH Aachen

The main aim of this work was to characterize the influence of thermo-mechanical heat treatment on aluminium alloys while laser forming. Therefore influences on grain structure, microstructure and mechanical properties had to be investigated. A huge number of experiments using different sheet thicknesses as well as different laser parameters gave possibility to detect kind and degree of all influences. In order to be able to distinguish between effects of classical metallurgy and those of short-time metallurgy, it was necessary to analyze different laser forming mechanisms. The temperature gradient mechanism is characterized by an inhomogeneous temperature field over the cross-section and a very high heating and cooling rate, whereas the buckling mechanism is defined by a nearly homogenous temperature distribution and a heating rate in the range of about 100 K/s. The changes in grain structure and microstructure, namely dislocation density, the building of a subgrain strcuture or precipitation structure, had to be detected as well as their influences on the local mechanical properties of the material. The correlation of all results in dependence on the laser forming mechanism gives possibility to derivate a material-oriented process chain for laser forming.