Lehrstuhl für Fertigungstechnologie, Universität Erlangen-Nürnberg

Detection and Prevention of Hot Cracks during Laser Welding of Aluminium Alloys Using Advanced Simulation Methods



Datum: 05.10.2006


Author


Reporter

  • Prof. Dr.-Ing. Dr.-Ing. E.h. mult. Dr.h.c. M. Geiger
  • Prof. Dr.-Ing. G. Sepold, Universität Bremen

Laser beam welding is already an established process in the industry to join various materials, including aluminium alloys. The advantages of this process against the conventional welding processes are overwhelming, even though there are some process conditional problems as well. Most of these problems have been solved, or can be controlled to a certain extent, so the demands of the present applications can be fulfilled. However, these problems hinder a wider spread of this process for more demanding applications such as the laser beam welding of outer skin parts of an aircraft. The most important difficulty in the case of aluminium laser beam welding is the hot cracking in connection with certain aluminium alloys. The proposed objective of the thesis was therefore the definition of a methodology to detect hot crack free welding parameters using the finite element method for any arbitrary welding task. The introduced methodology is based on the determination of the maximum CHoCO value for a given material or material combination. It is a maximum value since a simulation which results a value above this limit is very probably not hot crack minimised. With the appointment of this value, the evaluation of the hot cracking susceptibility using finite element simulations can be performed for an arbitrary welding task, significantly reducing the number of required experiments. Thus, with the help of this method time and costs can be saved during the process design.