Verbesserung der Stranggussqualität von hochlegierten Al-Walzbarren

Translated title of the contribution: Quality improvement of highly alloyed aluminium casting ingots

Bernd Prillhofer

Research output: ThesisDoctoral Thesis

Abstract

The adjustment of the melt quality to the specific requirements of semi-finished products is an essential success criterion at aluminium casthouses. Therefore, the selective reduction of non-metallic and inter-metallic inclusions within a process chain besides the removal of dissolved components like hydrogen, sodium, lithium and calcium, plays a very important role. Out of this, the removal of inclusions was already a very important issue of the refining process since the early years of the aluminium production. Due to the enormous growth of the secondary aluminium industry and the higher content of impurities of the input materials, characterisation of inclusions and furthermore the development of removal methods became highly important. This thesis examines possible mechanisms to enhance melt quality during melting, melt treatment and casting of the aluminium alloy EN AW-7075. The overall target is the removal of impurities from one process step to another, combined with the avoidance of a re-entry of inclusions. For this purpose the introduction describes the state of the art of the possible present inclusion in the aluminium melts, measurement methods for inclusion detection as well as a complete description of removal mechanisms and therefore common used techniques. The starting point of the experimental procedure is given by an overall process analysis of the casting line (melting furnace, casting furnace, melt treatment systems and the electromagnetic casting pit), the definition of used measurement techniques and a detailed description of possible inclusion formation mechanisms. The main part of the experimental work can be divided into two tasks. First, the influence of each process step on melt quality has been examined as a base for possibilities increasing efficiency. Out of this, the supply of the casting pit with high quality liquid metal can be guaranteed due the implemented arrangements, new developed process elements (supported by CFD-simulation work) and process concepts. The second main task focuses on the configuration of a new melt distribution system for the casting pit and the adaptation of the casting recipe. In this connection the formation of new inclusions can be avoided. The experimental work was assisted by CFD-simulation and water modelling.
Translated title of the contributionQuality improvement of highly alloyed aluminium casting ingots
Original languageGerman
QualificationDr.mont.
Supervisors/Advisors
  • Antrekowitsch, Helmut, Assessor A (internal)
  • Raupenstrauch, Harald, Assessor B (internal)
Publication statusPublished - 2009

Bibliographical note

embargoed until null

Keywords

  • melt quality inclusions hydrogen content gas purging treatment filtration EMC-casting melt distribution systems

Cite this