Untersuchung der mechanischen Eigenschaften einer Ti-6Al-4V-Legierung durch gezieltes Einstellen des Gefüges beim thermomechanischen Walzen von Blechen

Research output: ThesisMaster's ThesisResearch

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Abstract

A continuous development of the product qualitity and a product portfolio adaptation are required to be able to compete on a highly competitive global market. The company voestalpine Böhler Bleche GmbH & Co KG is eager to produce titanium alloy plates to sustain and develop its role as a producer of high quality sheets and plates for the aerospace market. Therefore, it is crucial to find a stable process for the new material to fulfill the requirements of the Airbus specification AIMS 03-18-001. Both laboratory experiments at the forming simulator at the Montanuniversity Leoben Forming Institute and in furnaces at the companies quality department as well as in-company rolling and heat treatment tests are conducted to achieve this aim. Firstly, a comprehensive literature research is applied to understand the correlation between the structure and the mechanical properties. In particular, the focus is on stable forming conditions during rolling which can be found in processing maps and on temperature-time-regimes to ensure a sufficient duplex structure. To achieve stable forming conditions recovery or recrystallisation is required. This can be seen in a constant compressive stress over the degree of deformation (φ) at the laboratory experiments. For deformation speed of 1 and 3 1/s sufficient temperatures are higher than 850 °C and for the speed of 10 1/s sufficient temperatures are higher than 875 °C, respectively. The maximum limit for the rolling interval is the β-transus temperature at 1.000 °C for Ti64-alloy. This is only dependent on the chemical composition. Similarly, the rolling experiment led to an ideal interval from 800 °C to 970 °C. To fulfill the required properties the optimization of the microstructure during the applied heat treatment is crucial. For this reason three treatments in the high area of the (α+β) field and one annealing are tested in the laboratory. All four approaches prove to be satisfying. Subsequently, in order to meet economical demands while still passing the aerospace requirements, mill annealing was successfully applied in an industrial experiment.

Details

Translated title of the contributionInvestigation of the mechanical properties of a specific by thermomechanical rolling adjusted microstructure in Ti-6Al-4V
Original languageGerman
QualificationDipl.-Ing.
Awarding Institution
Supervisors/Advisors
Award date29 Jun 2018
Publication statusPublished - 2018