Title page for ETD etd-09212005-124113


Document Type Master's Dissertation
Author Mukongo, Tshikele
URN etd-09212005-124113
Document Title Effect of titanium pick-up on mould flux viscosity in continuous casting of titanium-stabilised stainless steel
Degree M Eng (Metallurgical Engineering)
Department Materials Science and Metallurgical Engineering
Supervisor
Advisor Name Title
Prof P C Pistorius Committee Chair
Keywords
  • titanium nitride
  • flux metallurgy viscosity
  • perovskite
  • titanium steel
  • austenitic steel
  • ferritic steel
Date 2003-03-06
Availability unrestricted
Abstract
The behaviour of mould fluxes used in continuous casting of two Ti-stabilised stainless steels was investigated in terms of the level of titanium pick-up by the flux and the effect of this absorption of titanium on the viscosity of the fluxes. The two fluxes considered are respectively used for the casting of a ferritic steel (type 409) and an austenitic steel (type 321).

Concerning the titanium pick-up (expressed as Ti02), the Ti02 content of the flux stabilised at about 3-4% for the mould flux of the ferritic steel and at about 6% for the mould flux of the austenitic steel after 20 minutes of casting. At the same time due to the reduction of Si02 in the molten flux by TiN and Ti in the steel the basicity of the mould flux of the ferritic steel increased from 0.8 to 0.9 while it increased from 0.95 to 1.2 for the mould flux of the austenitic steel.

The SEM/EDS analysis of the sampled flux during casting showed only some spherical metallic droplets in the case of the mould flux of the ferritic steel but for the mould flux of the austenitic steel apart from the metallic droplets, some precipitates rich in Ca, Ti and O were identified in the glassy phases.

Rotational viscometry carried out on the two fluxes showed that there is a decrease in the viscosity of the fluxes with the absorption of Ti02, Ti2O3 and Ti3O5 in the range of 2 to 10 wt%, for temperatures from 1400C to 1200C.

The effect of Ti02 and Ti2O3 has been tested with the mould flux of the austenitic steel at a basicity of 1.2 to match the basicity which arises during casting. For temperatures of 12500C and below, the apparent viscosity of the flux increased markedly with the absorption of 10 % of Ti02 or Ti2O3. In both cases precipitation of perovskite (Ca2 Ti2O6 or Ca2 Ti2O5) was found to be responsible for the increase of the apparent viscosity of the flux of the austenitic steel.

2003, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria.

Please cite as follows:

Mukongo, T 2003, Effect of titanium pick-up on mould flux viscosity in continuous casting of titanium-stabilised stainless steel , MEng dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-09212005-124113/ >

H641/ag

Files
  Filename       Size       Approximate Download Time (Hours:Minutes:Seconds) 
 
 28.8 Modem   56K Modem   ISDN (64 Kb)   ISDN (128 Kb)   Higher-speed Access 
  dissertation.pdf 2.25 Mb 00:10:26 00:05:22 00:04:41 00:02:20 00:00:12

Browse All Available ETDs by ( Author | Department )

If you have more questions or technical problems, please Contact UPeTD.