Legierungs- und Prozessdesign von Al-Mg-Si Knetlegierungen für den Automobilbau

Translated title of the contribution: Alloy- and Processdesign of Al-Mg-Si Wrought Alloys for the Automotive Industry

Ramona Prillhofer

Research output: ThesisDoctoral Thesis

Abstract

Due to its unique material properties aluminum is used in a wide range of applications. Especially within the automotive industry, the lightweight material is of high importance. Driven by legal regulations to reduce CO2 emissions, demand for aluminium car body sheets will quadruple in the next four years. Materials for lightweight construction in automotive engineering must meet complex requirements. It is essential to combine high strength in service with good formability. The versatility of aluminium 6xxx (AlMgSi) alloys make them ideally suited for car body sheets, optimising specific mechanical properties - formability, corrosion resistance, joining and a stretcher strain free surface. Many standardized AlMgSi-alloys are already in industrial usage. Because of them wide tolerance range of alloying elements, alternative mechanical property variants are possible. However, this potential can only be realised by an understanding of the complex impact of different alloying element combinations and the influence of process parameters during production of semi-finished products. The purpose of the study was to evaluate practical options to adjust material performance of EN AW-6016 in terms of formability, strength in service and recyclability by changes in alloy- and process-design. Systematic variations of the chemical composition (Si, Mg, Cu, Mn and Fe) during laboratory- and industrial-trials led to an understanding of the multifarious effects of different element combinations. It has been shown that the material properties are influenced mainly by the ratio of Si/Mg and Si in excess. High strength in service is generated by increasing the volume fraction of age-hardening phases (Mg, Si, (Cu) ↑). To combine high strength with good formability Si in excess and the right ratio of Fe and Mn is required. However, the full potential of adjusting alloying elements can only be achieved by using the right process parameters, especially during heat treatment. It has been shown, that solution heat treatment followed by fast cooling and pre-aging have the most influence on the material properties of heat treatable car body sheets. Selection of annealing temperature and time depends mainly on the chemical composition and the final sheet application (for structural or exposed body parts).
Translated title of the contributionAlloy- and Processdesign of Al-Mg-Si Wrought Alloys for the Automotive Industry
Original languageGerman
QualificationDr.mont.
Supervisors/Advisors
  • Antrekowitsch, Helmut, Assessor A (internal)
  • Uggowitzer, Peter, Assessor B (external)
Publication statusPublished - 2015

Bibliographical note

no embargo

Keywords

  • Aluminium
  • AlMgSi
  • formability
  • strength
  • automotive
  • forming-tests

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