Title: "SENSITIVITY OF NON-DESTRUCTIVE TECHNIQUES TO CHARACTERIZE MICROSTRUCTURE AND CRYSTALLOGRAPHIC TEXTURE CHANGES DURING RECOVERY AND RECRYSTALIZATION OF LOW CARBON STEELS"
Author: KIZKITZA GURRUCHAGA ECHEVERRÍA
Date: 2010-02-09
Director: Dr. Ane Martínez de Guereñu Elorza
Abstract:
The main objective of the present thesis is to analyse the sensitivity of non destructive magnetic techniques to microstructure and crystallographic texture changes produced during the annealing of low carbon steels. Magnetic hysteresis loops and magnetic Barkhausen noise measurements have been used as non destructive techniques.
The effect of texture is analysed in terms of the average magnetocrystalline energy. This energy correlates the crystallographic texture with magnetic response. The magnetic field has been applied in three different directions in order to detect magnetic parameters affected by the crystallographic texture. Parameters affected by crystallographic texture have been distinguished.
The capacity of magnetic measurements to characterize recovery has been studied. The obtained results prove that several parameters derived from magnetic measurements are able to follow the progress of recovery. Additionally, the influence of solute content on recovery processes is analysed and the obtained results indicate that recovery processes are not sensitive to solute content.
Furthermore, the efficacy of some magnetic parameters has been studied in terms of non-destructively monitoring the onset and the progress of recrystallization in cold rolled low carbon steels. The results obtained prove that magnetic measurements could successfully be employed to monitor recrystallization processes non-destructively. Additionally, the evolution of magnetic parameters affected by crystallographic texture has been discussed in terms of crystallagrophic texture variations.
Moreover, the effect of different excitation signals on magnetic Barkhausen noise measurements has been analysed. Magnetic parameters measured with a filtered excitation signal are compared to the parameters measured without filtering it. These results show that the results of filtered excitation signal are more sensitive to the applied magnetic field direction.
