Enhanced pyrometry for continuous galvanizing of advanced high strength steel

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Automotive manufacturers increasingly rely on galvanized advanced high strength steels (AHSS) for lightweighting. Unfortunately, Canadian steel producers report unacceptably high AHSS rejection rates due to substandard strength and zinc layer adhesion. Much of the issue can be traced back to errors in the pyrometrically-inferred temperatures used to control the furnaces. These errors originate from the evolving surface state of the steel strip, in terms of roughness and oxide formation, which changes the spectral emissivity. The proposed research partnership between Prof Kyle Daun, a thermal radiation expert at the University of Waterloo, and Prof Myriam Brochu, a metallurgist at Polytechnique, will address this issue by: (i) elucidating how the AHSS surface state evolves during processing, and how this affects the spectral emissivity; and (ii) determining how temperature excursions affect strength and zinc adhesion. This information will be synthesized into an algorithm that provides robust steel strip temperature estimates using multiwavelength pyrometers. This research is supported by the Galvanized Autobody Partnership, convened by the International Zinc Association (IZA), and will be carried out in close collaboration with Stelco, a major producer of galvanized AHSS, Williamson, Inc. who supplies the pyrometers used by Stelco, SRB Controls, Inc., Williamson's Ontario distributor, and Teck Metals, Inc., Canada's largest producer of zinc. Stelco will use this research to enhance profitability of AHSS steel strip production, which will also benefit Canada's iron and zinc mining industry, who provide the feedstock needed to make galvanized AHSS steel. These savings will be passed down to Canadian automotive parts suppliers and OEMs, thereby benefiting the entire automotive supply chain and Canada's economy as a whole.