Optimization of Al-Mg and Al-Mg-Si alloys for cryogenic deformation

Belinda Gruber

Research output: ThesisDoctoral Thesis


The automotive industry is striving for aluminium alloys for lightweight construction with better formability in order to produce more complex components. A possibility to increase the ductility of aluminium is by lowering the forming temperature. The focus of this thesis is to investigate the mechanisms behind cryogenic deformation and to reveal the potential of an optimization of alloys to further enhance this behaviour. Results showed that the increase in strength and ductility is linked with a higher strain hardening rate accompanied by a low dynamic recovery compared to room temperature. This suggests a higher dislocation density at low temperatures, which was confirmed quantitatively via synchrotron experiments. Simultaneously, a change in dislocation character and thus a higher proportion of screw dislocations was detected. Low temperature deformation results also in a more homogeneous dislocation arrangement, shifting the critical dislocation accumulation causing failure to higher elongations and therefore improves formability. Not only the mechanism of the cryogenic forming, but also the influence of subsequent room temperature recovery and artificially ageing on the mechanical properties and the dislocation density was clarified. Recovery processes and the subsequent stability of the cryogenically deformed state are previously unnoticed challenges in further processing or scientific investigations. Hence, knowledge of these effects is crucial to build and develop new industrial processes utilizing cryogenic deformation.
Translated title of the contributionOptimierung von Al-Mg und Al-Mg-Si Legierungen für die kryogene Verformung
Original languageEnglish
Awarding Institution
  • Montanuniversität
  • Antrekowitsch, Helmut, Co-Supervisor (internal)
  • Clemens, Helmut, Assessor B (internal)
  • Pogatscher, Stefan, Assessor A (internal)
  • Uggowitzer, Peter, Co-Supervisor (internal)
Publication statusPublished - 2020

Bibliographical note

no embargo


  • aluminium alloys
  • cryogenic temperature
  • dislocation density
  • synchrotron radiation
  • recovery
  • ageing kinetics

Cite this