Kontrollerad gjutprocess för renare stål
In a multi-year project at Swerea Swecast AB studies on influence of dissolved gas on inclusions have been made. The knowledge about these parameters could be used to increase the quality of the final steel casting. The purpose of this thesis was to closer examine the impact of the oxygen level on inclusions.The questions asked were:? What was the amount of inclusions at different levels of oxygen?? What was the size of these inclusions at different levels of oxygen?? What does the inclusions consist of at different levels of oxygen?This was studied by measuring and sampling, sample preparation and microscopic analysis using an optical microscope and a scanning electron microscope (SEM). Measurements and sampling was performed at Smålands Stålgjuteri AB in Eksjö and at Swerea Swecast AB in Jönköping. At Smålands Stålgjuteri AB the measurements were performed in production while at Swerea Swecast AB the measurements were made in a way that the oxygen levels were provoked.The sample preparations were made at Swerea Swecast AB?s workshop and lab. Scanning electron microscopy (SEM) and light optic microscopy was used for the analysis. The data from these analyses were processed and charts and tables were prepared.The results from the light microscopy shows a difference in microstructure between the two samplings. The charts and tables that were obtained indicated that the number of inclusions correlated with the oxygen level. However, only to a certain extent because other parameters such as time and amount of deoxidizer have a greater effect. The size of the inclusions decreased with decreased oxygen level during deoxidation. As mentioned in the pre-study, oxides are the most common type of inclusions in steel. This was also the case in the current study.The results showed that the oxygen level can be used as an indicator of the necessary addition of deoxidiser.