Untersuchungen von bleifreien Aluminium-Automatenlegierungen

Translated title of the contribution: Investigations of lead-free aluminium alloys for machining

Susanne Koch

Research output: ThesisDoctoral Thesis

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Abstract

Due to current EU guidelines the production of aluminium machining alloys with lead-contents exceeding 0.4 wt.-% has been prohibited since 1st July 2008. Lead additions up to 2.0 wt. % provided the required machinability. The present study exhibits the effects of substituting lead by tin on materials characteristics like microstructure or mechanical properties. Moreover, altered behaviours at shaping, heat treatment, anodising, corrosion and machining are determined. Hence, the focus of the investigations is a comprehensive alloy specification. Based on the Aluminum Associations standards for lead containing AlCu alloys, implications of content variations of main alloying elements Cu, Mn, Mg and Sn have been investigated. It can be seen that increasing Sn contents improve shaping, accelerate artificial ageing and decelerate natural ageing. A-rated machinability can be achieved with Sn contents > 1 % in AlCuMgSn alloys. Furthermore, hard anodizing layers show a protective action on all Sn-containing materials. Alloy compositions for optimised mechanical properties and best possible machinability are modelled by design of experiments software. Medium Cu contents exhibit a good compromise between sufficiently high alloys strength and good machinability with simultaneous satisfying anodization and corrosion behaviour. A higher Mn content facilitates free cutting, whereas the Mg content has to be low to guarantee good machinability. Furthermore, part of this study is the investigation of possible effects of the micro alloying elements Ce and Y, respectively and additions of Co, Hf, Sr, Ti, V and Zr. Due to machinability high amounts of Hf and Ti should be avoided. However, Zr improves machinability significantly.
Translated title of the contributionInvestigations of lead-free aluminium alloys for machining
Original languageGerman
QualificationDr.mont.
Supervisors/Advisors
  • Clemens, Helmut, Assessor B (internal)
  • Antrekowitsch, Helmut, Assessor A (internal)
Publication statusPublished - 2010

Bibliographical note

no embargo

Keywords

  • Aluminum-Copper alloys
  • 2xxx aluminium alloys
  • 2000 series alloys
  • wrought alloy
  • tin
  • forming precipitation
  • hardening turning
  • surface finishing
  • surface treatment
  • manufacturing processing
  • impact extrusion

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