Bestimmung der Einflussfaktoren auf die Haftfestigkeit von Aluminium-Stahl-Verbundblechen

Translated title of the contribution: Investigation of parameters on bond strength of aluminium-steel sheet composites

Michaela Buchner

Research output: ThesisDoctoral Thesis

Abstract

Due to the increasing importance of light weight structures, modern composite materials have to be designed, because no single material meets all technological demands any longer. In practice, this problem is solved using metallic layered composites, e.g. aluminium and steel. If aluminium and steel are bonded by conventional fusion welding technologies, brittle intermetallic phases are formed. On this account, these materials are bonded using alternative joining technologies, e.g. roll cladding. To improve the bond strength of these composites, it is necessary to know the most important influencing factors. The aim of this thesis was a basic study of production, modelling and quantification of roll-cladded aluminium-steel sheet composites. In this context, the influence of the steel surface, the surface preparation, the pre-heat treatment of aluminium and steel sheets, the roll speed, the thickness reduction, the cooling conditions and the post-heat treatment on the bond strength of the composites were analysed using shear tension tests, cross tension tests as wells as reverse bend tests. Furthermore, the average distance between the sheets and the size of existing oxides, respectively, were analysed using SEM, the formation of intermetallic layers was observed using EDX, and the surface structure of the separated sheets was investigated using confocal laser scanning microscope. The estimation of the influence of the rolling parameters showed that the surface preparation, the thickness reduction, the pre-heating and an optionally post-heat treatment have a significant influence on the bond strength according to expectations, whereas roll speed and cooling rate have no relevant influence. The results of the rolling experiments showed that degreasing combined with grinding, pre-heat treatment of the steel sheets and hardening of the aluminium should be preferred to reach a good bond strength. The approach of the new developed bond strength model is based on numerical simulations at the macroscopic and microscopic level. The distribution of temperature and load as well as the surface expansion of the single sheets during the roll process are determined using a macroscopic level and the processes at the interface, like the alignment of the asperities, are investigated in the microscopic level.
Translated title of the contributionInvestigation of parameters on bond strength of aluminium-steel sheet composites
Original languageGerman
QualificationDr.mont.
Supervisors/Advisors
  • Antrekowitsch, Helmut, Assessor B (internal)
  • Buchmayr, Bruno, Assessor A (internal)
Publication statusPublished - 2008

Bibliographical note

embargoed until null

Keywords

  • aluminium steel lap welding roll bonding simulation

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