Bruch- und Verformungsverhalten von ultrafeinkörnigem Titan

Translated title of the contribution: Fracture and deformation behaviour of ultra fine grained titanium

Research output: ThesisDiploma Thesis

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Abstract

Because of superior mechanical and physical properties ultra fine grained (UFG) materials have been the centre of scientific interest for the last few years. This increasing interest in UFG materials first led to applications in the medical and aircraft sector. Especially titanium and its alloys, which are deformed by equal channel angular pressing (ECAP), have reached industrial attention. High pressure torsion (HPT) allows higher degrees of deformation in comparison to ECAP, leading to more grain refinement. This advantage was the reason for choosing HPT and not ECAP for this thesis. The objective of this work was to investigate the deformation and fracture behaviour of UFG titanium and selected titanium alloys. The deformation temperatures of the HPT process were chosen to be room temperature and 500°C. To confirm the homogeneity, which leads to a saturation in grain refinement of the HPT deformed samples, hardness measurements along the radial direction of the samples were conducted. Pure titanium and the TiNb13Zr13 alloy developed saturation regions for both deformation temperatures. On the contrary, the TiAl6V4 alloy only showed a saturation region at 500°C and not for HPT deformation at room temperature. Transmission electron microscopy investigations of pure titanium revealed that the deformation temperature does not have a large impact on the grain size. To characterize the deformation behaviour of pure titanium, tensile tests were conducted. They showed that the material HPT deformed at room temperature developed a higher tensile strength than the same material deformed at 500°C. On the other hand, the elongation before reduction in area, the elongation at fracture and the reduction in area do not differ significantly with respect to the deformation temperature. To investigate the fracture behaviour of UFG titanium compact tension samples were used. The experiments revealed a strong orientation dependency of the fracture toughness. For future applications and to enhance the industrial interest on UFG materials new processes which allow a sufficient degree of deformation and are economically viable need to be developed and explored.
Translated title of the contributionFracture and deformation behaviour of ultra fine grained titanium
Original languageGerman
QualificationDipl.-Ing.
Supervisors/Advisors
  • Pippan, Reinhard, Supervisor (internal)
Award date1 Jul 2011
Publication statusPublished - 2011

Bibliographical note

embargoed until null

Keywords

  • severe plastic deformation
  • HPT
  • titanium
  • titanium alloys
  • fracture behaviour
  • deformation behaviour

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