Year

2016

Degree Name

Doctor of Philosophy

Department

School of Mechanical, Materials and Mechatronic Engineering

Abstract

The studies of the influence of processing parameters and the effect of Nb content (from 0 to 1.4 wt. %) on the dynamic recrystallisation behaviour in model Ni-30 wt. % Fe alloys were conducted using a Gleeble-3500 thermo-mechanical processing simulator. Different processing parameters, such as solution treatment and deformation temperatures, strain and strain rate, were used to elucidate their effects on softening processes. It was shown that the deformation activation energy has increased from 362KJ/mol to 419 KJ/mol with an addition of 0.332 wt. % Nb to Ni-30 wt. % Fe alloy.

In order to clarify the evolution of dynamic recrystallisation, electron backscattering diffraction and transmission electron microscopy were used for systematic investigation of the interrupted strain specimens of Ni-30 wt.% Fe-0.331 wt.% Nb-0.04 wt.% C alloy subjected to plane strain compression at 1075 °C, 0.1 s-1 strain rate. Segmentation of partially recrystallised maps into dynamically recrystallised and unrecrystallised fractions has performed based on the grain orientation spread criterion.

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