Secondary steelmaking process stream optimization - inclusions, clogging, and segregation

钢中的微粒，也称为夹杂物，是非常不受欢迎的。尽管现代炼钢实践已经被开发以减轻大多数有害影响，但夹杂物对最终产品的性能是有害的，它们堵塞将熔融钢从二次炼钢转移到连续铸造工艺阶段的浸入式入口和计量喷嘴，并且它们影响铸造期间的溶质偏析/微观结构演变。目前，这些问题的解决方法是：（a）在钢包冶金过程中溶解液态氧化物系统（炉渣）中的夹杂物，（B）进行钙处理以控制形状，（c）频繁更换SEN。这些缓解策略中的每一种都有其自身的后果，对产品质量产生负面影响。考虑到夹杂物对钢质量的影响，需要优化从钢包冶金炉（LMF）到铸造产品的二次炼钢工艺流。 在与Gerdau和月桂钢的合作研究中，将开发一套基本模型，预测LMF中各种炼钢实践和产品中的钢清洁度，基于熔体与SEN内表面之间的相互作用的喷嘴堵塞，以及连续铸造期间随后的成分偏析和微观结构发展。将根据工厂数据和从工业赞助商处采集的样本对模型进行验证。从长远来看，这套模型将成为优化二次炼钢工艺流程的在线工具的基础。由于模型是基于热化学，运输现象和凝固的基本原理，修改程序将开发任何加拿大钢厂的应用程序。

Micro-particles in steel, also known as inclusions, are highly undesirable. Although modern steelmaking practices have been developed to mitigate most of the deleterious effects, inclusions are detrimental to the properties of the final product, they clog the submerged entry and metering nozzles that transfer molten steel from secondary steelmaking to the continuous casting process stages, and they affect solute segregation / microstructure evolution during casting. At present, these issues are dealt with by (a) dissolving inclusions in a liquid oxide system (slag) during ladle metallurgy, (b) calcium treatment for shape control and (c) frequent replacement of the SENs. Each of these mitigation strategies has their own consequences that negatively impact product quality. Given the impact of inclusions on steel quality, there is need to optimize the secondary steelmaking process stream from the Ladle Metallurgy Furnace (LMF) to the cast product. In this collaborative study with Gerdau and Laurel steel, a suite of fundamental models will be developed that predict steel cleanliness in a wide range of steelmaking practices and products in the LMF, nozzle clogging based on interactions between the melt and the inner surface of the SEN, and subsequent compositional segregation and microstructure development during continuous casting. The models will be verified against plant data and samples taken from the industrial sponsors. Long-term, this set of models will form the basis of an online tool for optimizing the secondary steelmaking process stream. As the models are based on the fundamentals of thermochemistry, transport phenomena, and solidification, a modification procedure will be developed enabling application for any Canadian steel mill.