The identification of the effect of high rate deformation on the microstructure and properties of titanium alloys

  • Michail Ntovas

Student thesis: Doctoral Thesis

Abstract

Material forming processes such as forming aerospace components, it is well known that are highly influenced by strain, strain rate and temperature. The effects of these parameters in flow stress and microstructure of titanium alloys are critical. The regime of strain rates where aerospace components such as aerofoil shapes for gas turbine engines are formed are between 1s-1 and 150 s-1. Conventional testing machines are unable to reach these strain rates and provide accurate information which the manufacturing community is currently interested. This project focused on the process optimization of a high strain rate forging simulator which is capable for strain rates up to 200s-1. An equipment bought bythe AFRC to deal with the lack of flow data. Data which will be used in the future for simulating high speed forging and extrusion. The experimental optimization was achieved through temperature optimization, sample relevant position to push rod and sample position to induction coil. Furthermore, the project investigates the high strain rate deformation of Ti6Al4V alloy with two distinct microstructures in terms of strain rate and temperature influence on the microstructure. The flow behaviour of the material were also investigated and modelled. The Hansel-Spittel (H&S) rheological law demonstrates good compliance with the high strain rate deformation of Ti6Al4V. Last but not least, the data obtained by the high strain rate deformation of the Ti6Al4V was used to create the process and instability maps for the Ti6Al4V. Forboth microstructures the stable and unstable deformation areas has been identified.
Date of Award23 Dec 2021
Original languageEnglish
Awarding Institution
  • University Of Strathclyde
SponsorsEPSRC (Engineering and Physical Sciences Research Council)
SupervisorPaul Blackwell (Supervisor) & Andrzej Rosochowski (Supervisor)

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