Effect of ferro-titanium alloying process on steel cleanness

The main factors were studied which influence the titanium yield during a ferro-titanium alloying process. The inclusion phases and removal effect were comparatively analyzed before and after ferro-titanium alloying. When controlling the activity of oxygen (a_o) before deoxidation below 350×10^-6, the interval time between Al and Ti addition above 3 min can guarantee the titanium yield above 85%. With a_o above 350×10^-6, the interval time between Al and Ti addition should be extended more than 5 min. Extending the interval time between Al and Ti addition can improve the titanium yield at the same a_o and Al_s. During RH refining, Al₂O₃ inclusions with the equivalent diameter above 200 μm can float and be removed within 5 min, but the removal time of AI-Ti-O inclusions with the same size is 1 to 2 min more than pure Al₂O₃. Al-Ti-O complex inclusions form around Al₂O₃ after the titanium alloy being added into the melt, and the titanium yield decreases due to the formation of these inclusions.