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

钢中的微小颗粒，也被称为夹杂物，是非常不受欢迎的。虽然现代炼钢工艺已被开发出来，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，它们堵塞了将钢水从二次炼钢转移到连铸过程的浸没入口和计量喷嘴，并影响了铸造过程中的溶质偏析/组织演变。目前，解决这些问题的方法是：(A)在钢包冶炼过程中将夹杂物溶解在液态氧化物系统(渣)中；(B)进行钙处理以控制形状；(C)频繁更换SENS。这些缓解策略中的每一种都有各自的后果，对产品质量产生负面影响。考虑到夹杂物对钢质量的影响，有必要优化从钢包冶金炉(LMF)到铸件的二次炼钢工艺流程。在这项与Gerdau和Laurel Steel的合作研究中，将开发一套基本模型，用于预测LMF中广泛的炼钢实践和产品中的钢洁净度、基于熔体和SEN内表面之间相互作用的水口堵塞以及随后的连铸过程中的成分偏析和组织发展。这些模型将与工厂数据和从工业赞助商那里获得的样本进行验证。从长远来看，这套模型将构成优化二次炼钢工艺流程的在线工具的基础。由于这些模型是基于热化学、传输现象和凝固的基本原理，因此将开发一种能够应用于任何加拿大钢厂的修改程序。

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.