Jfc Lins

Macrosegregation and porosity formation are investigated by both a numerical model and transient directional solidification experiments. The macrosegregation pattern, and the theoretical and apparent densities are presented as a function of the casting length. X-ray fluorescence spectrometry was used to determine the experimental macrosegregation profiles. The measurement of microporosity was performed by a pyknometry procedure. The local composition along an

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ABSTRACT The magnetic Barkhausen noise (MBN) in low carbon steel (0.034%C) was examined for two situations: after deformation and after recrystalization. The steel sheets previously received 50% of cold rolling and were heat treated for time periods between 15 to 540 min, originating different grain sizes. It was fo und that the maximum amplitude of MBN decreas es with annealing time. Electron back scat- tered diffraction (EBSD) shows that signi fi cant grain fragment ation occurred due to plastic deformation. The results are discussed with help of the Two Gaussian model for the MBN envelope. The major con tribution for MBN in the deformed sample was elimination of 90 closure domains. Displacement of 180 domain walls was limited in the deformed s ample, due to the grain fragmentation