Characterisation and modelling of segregation in continuously cast steel slab

Zhang, Dayue (2015). Characterisation and modelling of segregation in continuously cast steel slab. University of Birmingham. Ph.D.

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Abstract

The microsegregation of alloying elements (Mn, Si and Ni) in as-continuously cast steel slabs were characterised by scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS). The segregation profiles were obtained by cumulative profiles method using weighted interval rank sort (WJRS) and single element sort (SES) schemes. Analytical approaches (Ciyne-Kurz and Scheil), Thermo-Calc (thermodynamic) and DICTRA (considering the cross-effect of different elements) were used to predict the segregation behaviour of each steel slab. The segregation profiles predicted by DICTRA agree with experimental results better than those predicted by other models for each steel. But for slab I, root mean square deviation (RMSD) value used to determine the difference between DICTRA predicted and experimental segregation profiles was less than the experimental standard deviation. Directional solidification (OS) trials were carried out to verify DICTRA simulations in term of cooling rate. Although, DICTRA prediction using the measured cooling rate fell into the scatter band of WIRS profiles, discrepancy between the simulation and best fit to the profiles was found in the centre of both the dendritic and interdendritic regions. The discrepancy may indicate that the diffusions of Mn, Ni and Si in δ-ferrite used in DICTRA are faster than real situations.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

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