Super Quality Melts for State-of-the-Art Steel

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Ridding inclusions from liquid steel prior to casting and solidification has vexed steelmakers for many years. Large inclusion agglomerates are sufficiently buoyant, that they can float up to the surface of the liquid steel, if given sufficient time, prior to solidification. However, the smaller inclusion clusters of less than ~60 microns have such low float-out velocities that they remain trapped in the liquid steel, as do other entrained particles, and end-up in the solidified steel. All these inclusions can be very harmful to a steel's properties. We have been working on redressing this problem, by considering how to create microbubble swarms in liquid steel, so as to intercept all sizes of inclusions, and displace them from various "baths" of liquid steel. Using mathematical and full scale water models, we have been able to demonstrate a possible solution to our industrial partners, RTFT, RTMP, and NSC. They enthusiastically agree to support this initiative which will represent a) improved metal powder quality at RTMP, b) improved removal of MPE (metal powder entrainment) at RTFT, and c) improved steel quality at NSC. This CRD program will start, by confirming our water model results to date, using our full scale tundish systems for RTIT and NSC, and a one-third scale model of the RTMP Tundish. Simultaneously, a low temperature, non-wetting, low melting point alloy ("Cerrolow 136"), will be used to confirm the value of this novel "microbubble cleaning" technology, using a recirculating liquid metal loop incorporating controlled gas injection. We will then design equivalent liquid steel tests for Nippon Steel Corporation(NSC), and for the Rio Tinto Metal Powders (RTMP) and Rio Tinto Fer & Titane (RTFT) plants. Given that RTMP is the largest supplier of metal powders to the automobile industry in North America, while RTFT is also a supplier of auto-parts, this will firstly benefit, as well as their secondary metal parts suppliers. This collaboration with NSC will increase the competitiveness of Canada's steelmaking expertise, and lead to the early adoption of the technology, with the promise of dramatic improvements for future steel quality & properties, for the benefit of all.