Effect of pressurized spray cooling on microstructure gradients in thicker hot strip products

钢材新产品开发继续在经济社会中发挥重要作用。钢铁发展的步伐不断加快，是由汽车制造、建筑和能源等关键行业的需求推动的。开发新钢材需要加深对冶金基础知识的了解，并不断实现钢铁生产设施的现代化。加速冷却已成为生产具有细晶和/或多相组织的热机械控制加工热轧钢材的关键技术，这些组织和性能现在越来越多地被要求用于苛刻的应用。使用精心设计的加工路径而不是添加合金化是制造这些高性能钢的一种有吸引力的方法。轧制台上的冷却路径起着至关重要的作用，因为它可以用来定制从面心立方(FCC)晶体结构的奥氏体到体心立方(BCC)晶体结构的铁素体的相变。具体来说，根据钢的化学成分和加工路径，可以获得不同的相变产物，以创建复杂的多相组织，这为性能设计提供了新的范式。包括安赛乐米塔尔多法斯科(AMD)在内的加拿大钢铁行业正在积极升级其超负荷工作台冷却能力。这里一个特别的挑战是生产更厚的量规钢，例如管线管，因为密集冷却，例如在加压喷涂单元中，可能会导致穿透厚度的组织/性能变化。工艺模型的开发将对这些附加值产品的高质量和最小变异性产生越来越大的影响。该项目是与AMD合作开发的新一代管线钢热传递和相变动力学结合的跳动表模型。将在中试规模的压水台设施和热机械加工实验室进行实验研究，为模型的开发提供指导。提出的模型将用工业数据进行验证。该项目为三名研究生提供了培训机会。

The development of new steel products continues to play an important role in the economy and society. The ever increasing pace of steel development is driven by the demands of critical sectors like automobile manufacturing, construction and energy. Developing new steels requires to deepen the knowledge in the underlying metallurgy and constant modernization of steel production facilities. Accelerated cooling has become a key technology to produce thermo-mechanically controlled processed hot-rolled steels with fine grained and/or multi-phase microstructures and the mechanical properties that are now increasingly required for demanding applications. Using well-designed processing paths rather than alloying additions is an attractive approach to manufacture these high-performance steels. The cooling path on the runout table 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 path, different transformation products can be obtained to create complex multi-phase microstructures which offer new paradigms for the design of properties. The Canadian steel industry, including ArcelorMittal Dofasco (AMD), is actively engaged in upgrading their runout table cooling capabilities. A particular challenge is here the production of thicker gage steels, e.g. line pipe, because the intense cooling, e.g. in a pressurized spray unit, may lead to through-thickness microstructure/property variations. The development of process models will have an increasing impact for making these value-added products with high quality and minimum variability. The proposed project is conductecd in collaboration with AMD to develop a next generation runout table model that combines heat transfer and phase transformation kinetics for line pipe steels. Experimental studies will be carried out on a pilot scale runout table facility and the thermo-mechanical processing laboratory to provide guidance for the model development. The proposed model will be validated with industrial data. The project offers training opportunities for three graduate students.