Effect of Scale on Runout Table Heat Transfer

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The development of new steel products continues to be an important contributor in the economy and society. The increased pace of steel development is primarily driven by the demands of the automotive industry. Here, advanced high strength steels take a crucial role to reduce vehicle weight and thereby improving fuel economy as a critical aspect to decrease greenhouse gas emissions. These steels have attractive properties including superior strength-formability balance and crash worthiness that are obtained by increased alloying additions (e.g. Mn, Si) and stringent process control. The cooling path on the runout table in a hot mill takes a critical role as it can be used to tailor the phase transformation from austenite with a face-centred cubic (FCC) crystal structure to ferrite with a body-centred cubic (BCC) crystal structure. In detail, depending on steel chemistry and processing, complex multi-phase microstructures can be engineered consisting of different transformation products which offer new paradigms for the design of properties. In particular during hot rolling of steels with higher Si contents a persistent oxide scale may form that affects cooling efficiencies on the runout table leading to unacceptable property variations. Thus, it is important to develop optimized runout table processing strategies to mitigate the role of scale. The proposed project is designed to advance fundamental knowledge on the effect of scale on heat transfer. Dedicated pilot-scale runout table tests will be conducted to quantify heat extraction rates and advanced characterization techniques will be employed to determine scale structure and chemistry. The proposed project is conducted in close collaboration with ArcelorMittal Dofasco - Canada's leading producer of automotive steel sheets - and aims to provide new insight in designing optimized cooling strategies. The project offers training opportunities for a PhD student who will develop a unique skill level by combining heat transfer studies with microstructure characterization.