Grain size control in steel by means of dispersed non-metallic inclusions - GRAINCONT : final report

This was a collaborative project involving Kungliga Tekniska Högskolan, Helsinki University of Technology, Centre de Recherches Métallurgiques, ArcelorMittal and ComdiCast AB. Stiftelsen for Industriell og Teknisk Forskning was also participating as subcontractor. The project objectives were to create and improve fundamental knowledge of grain size control by means of dispersoidic inoculants in the steel microstructure and to develop and establish a new addition technique applicable for steel continuous casting. Thermodynamic studies and modelling of potential inoculants yielded results which could be utilised during the progress of the project. Laboratory testing of inoculants systems and evaluation of the as-cast samples gave information regarding the potential grain refining effects. Ingots for further processing were produced. Research regarding production of inoculants alloys, both with exogenous particles and ferroalloys for in situ formation of inclusions (e.g. particles) in steel, was carried out. Grain refining effect of produced inoculants alloys was tested. An injection technique for addition of inoculants alloys powder directly in the continuous casting mould through a special submerged entry nozzle was developed and tested in pilot plant scale. Grain refining effect on ascast material was evaluated and samples for further processing was also here produced. A selection of the various steel samples produced in the project underwent hot and cold rolling simulation tests and the effects of grain refining on microstructure and mechanical properties of final products were evaluated. Finally, the results were summarised and an overall project evaluation was made.